diff --git a/.build_rtd_docs/Doxyfile b/.build_rtd_docs/Doxyfile
index 13bdf99d1e7..1dc8033b435 100644
--- a/.build_rtd_docs/Doxyfile
+++ b/.build_rtd_docs/Doxyfile
@@ -37,7 +37,7 @@ PROJECT_NAME           = "MODFLOW 6"
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = "version 6.2.2"
+PROJECT_NUMBER         = "version 6.5.0.dev0"
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
diff --git a/.build_rtd_docs/conf.py b/.build_rtd_docs/conf.py
index bfd38623e25..40b117a9f22 100644
--- a/.build_rtd_docs/conf.py
+++ b/.build_rtd_docs/conf.py
@@ -56,6 +56,15 @@
 # copy the file
 shutil.copy(src, dst)
 
+# -- copy deprecations markdown ---------------------------------------------
+print("Copy the deprecations table")
+dstdir = "_mf6run"
+fpth = "deprecations.md"
+src = os.path.join("..", "doc", "mf6io", "mf6ivar", "md", fpth)
+dst = os.path.join(dstdir, fpth)
+# copy the file
+shutil.copy(src, dst)
+
 # -- build the mf6io markdown files -----------------------------------------
 print("Build the mf6io markdown files")
 pth = os.path.join("..", "doc", "mf6io", "mf6ivar")
@@ -140,11 +149,9 @@
 # so a file named "default.css" will overwrite the builtin "default.css".
 html_static_path = ["_static"]
 
-html_context = {
-    "css_files": [
-        "_static/theme_overrides.css",  # override wide tables in RTD theme
-    ],
-}
+html_css_files = [
+    "_static/theme_overrides.css",  # override wide tables in RTD theme
+]
 
 # html_theme_options = {
 #     "github_url": "https://github.com/MODFLOW-USGS/modflow6",
diff --git a/.build_rtd_docs/index.rst b/.build_rtd_docs/index.rst
index e5b8ee8cae1..813d5a4daff 100644
--- a/.build_rtd_docs/index.rst
+++ b/.build_rtd_docs/index.rst
@@ -14,4 +14,5 @@ Contents:
    MODFLOW 6 Source Code Documentation <https://modflow-usgs.github.io/modflow6/>
    mf6io
    _mf6run/run-time-comparison.md
+   _mf6run/deprecations.md
 
diff --git a/.build_rtd_docs/requirements.rtd.txt b/.build_rtd_docs/requirements.rtd.txt
index e531a07c623..979de2f6768 100644
--- a/.build_rtd_docs/requirements.rtd.txt
+++ b/.build_rtd_docs/requirements.rtd.txt
@@ -1,5 +1,6 @@
 numpy
 bmipy
+sphinx>=4
 sphinx_markdown_tables
 nbsphinx
 nbsphinx_link
@@ -7,7 +8,7 @@ ipython
 ipykernel
 rtds_action
 myst-parser
-sphinx_rtd_theme
+sphinx_rtd_theme>=1
 pytest
 filelock
 modflow-devtools
\ No newline at end of file
diff --git a/.doc/conf.py b/.doc/conf.py
index 599c330ac4d..8ed07df6dda 100644
--- a/.doc/conf.py
+++ b/.doc/conf.py
@@ -112,14 +112,13 @@
 # relative to this directory. They are copied after the builtin static files,
 # so a file named "default.css" will overwrite the builtin "default.css".
 html_static_path = ["_static"]
-
 html_context = {
     "github_repo": "modflow6",
     "doc_path": ".doc",
-    "css_files": [
-        "_static/theme_overrides.css",  # override wide tables in RTD theme
-    ],
 }
+html_css_files = [
+    "_static/theme_overrides.css",  # override wide tables in RTD theme
+]
 
 html_theme_options = {}
 
diff --git a/.doc/requirements.txt b/.doc/requirements.txt
index 2174ec428a1..7c642ad9cda 100644
--- a/.doc/requirements.txt
+++ b/.doc/requirements.txt
@@ -2,5 +2,6 @@ sphinx_markdown_tables
 ipython
 ipykernel
 rtds_action
-sphinx_rtd_theme
+sphinx>=4
+sphinx_rtd_theme>=1
 myst-parser
diff --git a/.fprettify.yaml b/.fprettify.yaml
index c19702b116f..553ef061397 100644
--- a/.fprettify.yaml
+++ b/.fprettify.yaml
@@ -1,6 +1,6 @@
 # MODFLOW 6 configuration for fprettify
 # run from root directory using
-# fprettify -c distribution/.fprettify.yaml SRC
+# fprettify -c .fprettify.yaml SRC
 whitespace-plusminus: 1
 whitespace-multdiv: 1
 line-length: 82
diff --git a/.gitattributes b/.gitattributes
index e5e837d1e7f..9134554730d 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -13,3 +13,8 @@
 *.png binary
 *.jpg binary
 *.pdf binary
+
+# Configure github-linguist
+*.inc linguist-language=Fortran
+.build_rtd_docs/** linguist-documentation
+.doc/** linguist-documentation
diff --git a/.github/ISSUE_TEMPLATE/bug_report.md b/.github/ISSUE_TEMPLATE/bug_report.md
index bbfd8d081ab..6d7a3d18f05 100644
--- a/.github/ISSUE_TEMPLATE/bug_report.md
+++ b/.github/ISSUE_TEMPLATE/bug_report.md
@@ -10,7 +10,7 @@ assignees: ''
 **Describe the bug**
 A clear and concise description of what the bug is.
 
-**To Reproduce**
+**To reproduce**
 Steps to reproduce the behavior:
 1. Go to '...'
 2. Click on '....'
@@ -23,6 +23,7 @@ A clear and concise description of what you expected to happen.
 **Screenshots**
 If applicable, add screenshots to help explain your problem.
 
-**Desktop (please complete the following information):**
- - OS: [e.g. macOS, Linux, Windows]
- - Version [e.g. 22]
+**Environment**
+ - Operating system (e.g. macOS, Linux, Windows) and version
+ - MODFLOW 6 version (if installed via distribution)
+ - Compiler toolchain/version (if built from source)
diff --git a/.github/PULL_REQUEST_TEMPLATE/pull_request_template.md b/.github/PULL_REQUEST_TEMPLATE/pull_request_template.md
new file mode 100644
index 00000000000..1affcbe0ed5
--- /dev/null
+++ b/.github/PULL_REQUEST_TEMPLATE/pull_request_template.md
@@ -0,0 +1,8 @@
+Feel free to remove check-list items that aren't relevant to your change.
+
+- [ ] Closes #xxxx
+- [ ] Passed autotests
+- [ ] Formatted source files with `fprettify`
+- [ ] Updated definition (*.dfn) files with new or modified options
+- [ ] Described new options, features or behavior changes in release notes
+- [ ] Updated meson files, makefiles, and Visual Studio project files if new source files added
\ No newline at end of file
diff --git a/.github/common/fortran_format_check.py b/.github/common/fortran_format_check.py
index 8452e5a69c6..a2c6eb1411e 100644
--- a/.github/common/fortran_format_check.py
+++ b/.github/common/fortran_format_check.py
@@ -18,7 +18,8 @@
 ]
 
 # Exclude these files from checks
-excludefiles = ["src/Utilities/InputOutput.f90"]  # excluded until refactored
+excludefiles = []  # add excluded files here
+
 
 class FortranFormatCheck:
     """
@@ -99,6 +100,7 @@ def _excluded(self, path: Path) -> bool:
 
         return False
 
+
 if __name__ == "__main__":
     parser = argparse.ArgumentParser(
         "MODFLOW 6 fortran format source code verification"
@@ -106,9 +108,7 @@ def _excluded(self, path: Path) -> bool:
     parser.add_argument(
         "-r", "--root", help="path to MODFLOW 6 repository root directory"
     )
-    parser.add_argument(
-        "-v", "--verbose", action="store_true", help="verbose"
-    )
+    parser.add_argument("-v", "--verbose", action="store_true", help="verbose")
     args = parser.parse_args()
 
     # set MODFLOW 6 repository root
diff --git a/.github/common/msvs_vfproj_check.py b/.github/common/msvs_vfproj_check.py
new file mode 100644
index 00000000000..80c1f3d719d
--- /dev/null
+++ b/.github/common/msvs_vfproj_check.py
@@ -0,0 +1,68 @@
+import xml.etree.ElementTree as ET
+from pathlib import Path
+
+
+def get_source_files(src_folder):
+    p = Path(".")
+    src_files = []
+    print(f"Processing {src_folder} folder")
+    ftypes = ("*.[fF]9[05]", "*.inc")
+    src_files = []
+    for ft in ftypes:
+        src_files.extend(p.glob(f"{src_folder}/**/{ft}"))
+    return src_files
+
+
+def get_msvs_files(vfproj_file):
+    print(f"Processing {vfproj_file}")
+    tree = ET.parse(vfproj_file)
+    root = tree.getroot()
+    msvs_files = []
+    for f in root.iter("File"):
+        s = f.attrib["RelativePath"]
+        s = s.replace("\\", "/")
+        s = s.replace("../", "")
+        fpath = Path(s)
+        msvs_files.append(fpath)
+    return msvs_files
+
+
+def check_files(name, src_files, msvs_files):
+    print(
+        f"Verifying {name} files referenced in msvs project files are in src folder..."
+    )
+    s, m = set(src_files), set(msvs_files)
+    diff = s ^ m
+    from pprint import pformat
+
+    assert not any(diff), (
+        f"{name} src files don't match msvs project file\n"
+        f"=> symmetric difference:\n{pformat(diff)}\n"
+        f"=> src - msvs:\n{pformat(s - m)}\n"
+        f"=> msvs - src:\n{pformat(m - s)}\n"
+        "Check to make sure msvs project file is consistent with source files."
+    )
+
+
+def check_mf6():
+    # get list of source files and files referenced in msvs project files
+    src_files = get_source_files("src")
+    msvs_files = []
+    for vfproj in ["./msvs/mf6core.vfproj", "./msvs/mf6.vfproj"]:
+        msvs_files.extend(get_msvs_files(vfproj))
+    check_files("MF6", src_files, msvs_files)
+
+
+def check_bmi():
+    # get list of source files and files referenced in msvs project files
+    src_files = get_source_files("srcbmi")
+    msvs_files = []
+    for vfproj in ["./msvs/mf6bmi.vfproj"]:
+        msvs_files.extend(get_msvs_files(vfproj))
+    check_files("BMI", src_files, msvs_files)
+
+
+if __name__ == "__main__":
+    check_mf6()
+    check_bmi()
+    print("msvs project (vfproj) files appear up-to-date...")
diff --git a/.github/common/update_compat_tables.py b/.github/common/update_compat_tables.py
new file mode 100644
index 00000000000..59255741806
--- /dev/null
+++ b/.github/common/update_compat_tables.py
@@ -0,0 +1,35 @@
+"""
+Inserts Markdown compatibility tables
+between tags in target Markdown file.
+"""
+
+import re
+import sys
+from pathlib import Path
+
+name = sys.argv[1]  # name of the table, e.g. "compile", "test"
+compat_path = Path(sys.argv[2])  # compatibility table path
+update_path = Path(sys.argv[3])  # path to file to update
+
+assert compat_path.is_file()
+assert update_path.is_file()
+
+with open(compat_path, "r") as compat:
+    table = "".join(compat.readlines())
+    r = re.compile(
+        r"<!\-\- "
+        + name
+        + r" compat starts \-\->.*<!\-\- "
+        + name
+        + r" compat ends \-\->",
+        re.DOTALL,
+    )
+    ct = (
+        "<!-- "
+        + name
+        + " compat starts -->{}<!-- ".format("\n{}\n".format(table))
+        + name
+        + " compat ends -->"
+    )
+    readme = update_path.open().read()
+    update_path.open("w").write(r.sub(ct, readme))
diff --git a/.github/common/wide_compat_reports.py b/.github/common/wide_compat_reports.py
new file mode 100644
index 00000000000..f2ffb531ba1
--- /dev/null
+++ b/.github/common/wide_compat_reports.py
@@ -0,0 +1,39 @@
+"""
+Converts compatibility reports from long to wide format
+and makes a markdown table from the wide format report.
+"""
+
+from pathlib import Path
+import pandas as pd
+import sys
+
+ip = Path(sys.argv[1])  # input file path
+op = Path(sys.argv[2])  # output file path
+assert ip.is_file()
+assert ip.suffix == ".csv"
+assert op.suffix == ".csv"
+
+# read long CSV
+df = pd.read_csv(ip)
+
+# pivot and sort
+df = pd.pivot(
+    df,
+    index="runner",
+    columns=["compiler", "version"],
+    values="support",
+).sort_values(by=["runner"])
+
+# write wide CSV
+df.to_csv(op)
+
+# write wide markdown table
+with open(op.with_suffix(".md"), "w") as file:
+    file.write(
+        df.to_markdown()
+        .replace("nan", "")
+        .replace("(", "")
+        .replace(")", "")
+        .replace(",", "")
+        .replace("'", "")
+    )
diff --git a/.github/compat/comp.csv b/.github/compat/comp.csv
new file mode 100644
index 00000000000..32e0a1b4c31
--- /dev/null
+++ b/.github/compat/comp.csv
@@ -0,0 +1,9 @@
+compiler,gcc,gcc,gcc,gcc,gcc,gcc,gcc,intel-classic,intel-classic,intel-classic,intel-classic,intel-classic,intel-classic,intel-classic,intel-classic,intel-classic,intel-classic,intel,intel,intel,intel,intel,intel,intel,intel,intel,intel
+version,10,11,12,13,7,8,9,2021.1,2021.10,2021.2,2021.3,2021.4,2021.5,2021.6,2021.7,2021.8,2021.9,2021.1,2021.2,2021.4,2022.0,2022.1,2022.2.1,2022.2,2023.0,2023.1,2023.2
+runner,,,,,,,,,,,,,,,,,,,,,,,,,,,
+macos-11,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,,,,,,,,,,
+macos-12,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,,,,,,,,,,
+ubuntu-20.04,&check;,&check;,,,&check;,&check;,&check;,&check;,&check;,&check;,,&check;,&check;,&check;,&check;,&check;,&check;,,,,,,&check;,&check;,,,&check;
+ubuntu-22.04,&check;,&check;,&check;,&check;,,,&check;,&check;,&check;,&check;,,&check;,&check;,&check;,&check;,&check;,&check;,,,,,,&check;,&check;,,,&check;
+windows-2019,&check;,&check;,&check;,&check;,,,&check;,,&check;,,,,,&check;,&check;,&check;,&check;,,,,,,,&check;,,,&check;
+windows-2022,&check;,&check;,&check;,&check;,,,&check;,,&check;,,,,,&check;,&check;,&check;,&check;,,,,,,,&check;,,,&check;
diff --git a/.github/compat/test.csv b/.github/compat/test.csv
new file mode 100644
index 00000000000..a029341ceef
--- /dev/null
+++ b/.github/compat/test.csv
@@ -0,0 +1,9 @@
+compiler,gcc,gcc,gcc,gcc,gcc,gcc,gcc,intel-classic,intel-classic,intel-classic,intel-classic,intel-classic,intel-classic,intel-classic,intel-classic,intel-classic,intel-classic,intel,intel,intel,intel,intel,intel,intel,intel,intel,intel
+version,10,11,12,13,7,8,9,2021.1,2021.10,2021.2,2021.3,2021.4,2021.5,2021.6,2021.7,2021.8,2021.9,2021.1,2021.2,2021.4,2022.0,2022.1,2022.2.1,2022.2,2023.0,2023.1,2023.2
+runner,,,,,,,,,,,,,,,,,,,,,,,,,,,
+macos-11,&check;,&check;,&check;,&check;,&check;,&check;,&check;,&check;,,&check;,&check;,&check;,&check;,&check;,&check;,,,,,,,,,,,,
+macos-12,&check;,&check;,&check;,&check;,,,,&check;,,&check;,&check;,&check;,&check;,&check;,&check;,,,,,,,,,,,,
+ubuntu-20.04,&check;,&check;,,,&check;,&check;,&check;,&check;,,&check;,,&check;,&check;,&check;,&check;,,,,,,,,,,,,
+ubuntu-22.04,&check;,&check;,&check;,&check;,,,&check;,&check;,,&check;,,&check;,&check;,&check;,&check;,,,,,,,,,,,,
+windows-2019,,,,&check;,,,,,,,,,,&check;,&check;,,,,,,,,,,,,
+windows-2022,&check;,&check;,&check;,&check;,,,&check;,,,,,,,&check;,&check;,,,,,,,,,,,,
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 75c7b43d4b6..b0333674e46 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,23 +1,43 @@
 name: MODFLOW 6 continuous integration
 on:
   push:
-    branches:
-      - master
-      - develop
-      - ci-diagnose*
     paths-ignore:
       - '**.md'
-      - 'doc/**'
+      - '**.pdf'
+      - '**.tex'
+      - '**.jpg'
+      - '**.jpeg'
+      - '**.png'
+      - '**.bbl'
+      - '**.bib'
+      - 'doc/**.dat'
+      - 'doc/**.ipynb'
+      - 'doc/**.py'
+      - 'doc/**.sh'
+      - 'doc/**.xlsx'
+      - '.hpc/**'
   pull_request:
     branches:
       - master
       - develop
     paths-ignore:
       - '**.md'
-      - 'doc/**'
+      - '**.pdf'
+      - '**.tex'
+      - '**.jpg'
+      - '**.jpeg'
+      - '**.png'
+      - '**.bbl'
+      - '**.bib'
+      - 'doc/**.dat'
+      - 'doc/**.ipynb'
+      - 'doc/**.py'
+      - 'doc/**.sh'
+      - 'doc/**.xlsx'
+      - '.hpc/**'
 jobs:
   lint:
-    name: Lint (fprettify)
+    name: Check format
     runs-on: ubuntu-latest
     defaults:
       run:
@@ -25,7 +45,7 @@ jobs:
     steps:
 
       - name: Checkout modflow6
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup Micromamba
         uses: mamba-org/setup-micromamba@v1
@@ -37,22 +57,25 @@ jobs:
       - name: Check Fortran source formatting
         run: python .github/common/fortran_format_check.py
 
+      - name: Check msvs project files
+        run: python .github/common/msvs_vfproj_check.py
+
   build:
-    name: Build (gfortran 12)
+    name: Build
     runs-on: ubuntu-22.04
     defaults:
       run:
         shell: bash -l {0}
     env:
       FC: gfortran
-      GCC_V: 12
+      GCC_V: 13
     steps:
 
       - name: Checkout modflow6
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       
       - name: Setup gfortran ${{ env.GCC_V }}
-        uses: awvwgk/setup-fortran@main
+        uses: fortran-lang/setup-fortran@v1
         with:
           compiler: gcc
           version: ${{ env.GCC_V }}
@@ -70,29 +93,39 @@ jobs:
       - name: Meson compile
         run: meson compile -C builddir
 
+      - name: Show build log
+        if: failure()
+        run: cat builddir/meson-logs/meson-log.txt
+
       - name: Meson test
         run: meson test --verbose --no-rebuild -C builddir
 
   smoke_test:
-    name: Smoke test (gfortran 12)
+    name: Smoke test
     runs-on: ubuntu-22.04
     defaults:
       run:
         shell: bash -l {0}
     env:
       FC: gfortran
-      GCC_V: 12
+      GCC: 13
     steps:
       - name: Checkout modflow6
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           path: modflow6
+      
+      - name: Checkout test-drive
+        uses: actions/checkout@v4
+        with:
+          repository: fortran-lang/test-drive
+          path: test-drive
 
-      - name: Setup GNU Fortran ${{ env.GCC_V }}
-        uses: awvwgk/setup-fortran@main
+      - name: Setup GNU Fortran ${{ env.GCC }}
+        uses: fortran-lang/setup-fortran@v1
         with:
           compiler: gcc
-          version: ${{ env.GCC_V }}
+          version: ${{ env.GCC }}
 
       - name: Setup Micromamba
         uses: mamba-org/setup-micromamba@v1
@@ -101,12 +134,27 @@ jobs:
           cache-environment: true
           cache-downloads: true
 
+      - name: Build test-drive
+        working-directory: test-drive
+        run: |
+          meson setup builddir --prefix=$(pwd) --libdir=lib
+          meson install -C builddir
+          echo "PKG_CONFIG_PATH=$(pwd)/lib/pkgconfig:$PKG_CONFIG_PATH" >> $GITHUB_ENV
+
       - name: Build modflow6
         working-directory: modflow6
         run: |
           meson setup builddir -Ddebug=false --prefix=$(pwd) --libdir=bin
           meson install -C builddir
-          meson test --verbose --no-rebuild -C builddir
+
+      - name: Show build log
+        if: failure()
+        working-directory: modflow6
+        run: cat builddir/meson-logs/meson-log.txt
+    
+      - name: Unit test programs
+        working-directory: modflow6
+        run: meson test --verbose --no-rebuild -C builddir
 
       - name: Update flopy
         working-directory: modflow6/autotest
@@ -127,8 +175,8 @@ jobs:
             pytest -v -n auto --durations 0 -S
           fi
 
-  test_gfortran_latest:
-    name: Test (gfortran 12)
+  test_gfortran:
+    name: Test gnu fortran
     needs:
       - lint
       - build
@@ -143,30 +191,30 @@ jobs:
         shell: bash -l {0}
     env:
       FC: gfortran
-      GCC_V: 12
+      GCC: 13
     steps:
       - name: Checkout modflow6
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           path: modflow6
 
       - name: Checkout modflow6-testmodels
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: MODFLOW-USGS/modflow6-testmodels
           path: modflow6-testmodels
       
       - name: Checkout modflow6-examples
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: MODFLOW-USGS/modflow6-examples
           path: modflow6-examples
       
-      - name: Setup GNU Fortran ${{ env.GCC_V }}
-        uses: awvwgk/setup-fortran@main
+      - name: Setup GNU Fortran ${{ env.GCC }}
+        uses: fortran-lang/setup-fortran@v1
         with:
           compiler: gcc
-          version: ${{ env.GCC_V }}
+          version: ${{ env.GCC }}
 
       - name: Setup Micromamba
         uses: mamba-org/setup-micromamba@v1
@@ -183,7 +231,15 @@ jobs:
         run: |
           meson setup builddir -Ddebug=false --prefix=$(pwd) --libdir=bin
           meson install -C builddir
-          meson test --verbose --no-rebuild -C builddir
+
+      - name: Show build log
+        if: failure()
+        working-directory: modflow6
+        run: cat builddir/meson-logs/meson-log.txt
+      
+      - name: Unit test programs
+        working-directory: modflow6
+        run: meson test --verbose --no-rebuild -C builddir
 
       - name: Update flopy
         working-directory: modflow6/autotest
@@ -207,11 +263,9 @@ jobs:
             pytest -v -n auto --durations 0 -m "not large"
           fi
       
-      # steps below run only on Linux to test distribution procedures, e.g.
-      # compiling binaries, building documentation
       - name: Checkout usgslatex
         if: runner.os == 'Linux'
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: MODFLOW-USGS/usgslatex
           path: usgslatex
@@ -230,31 +284,15 @@ jobs:
         if: runner.os == 'Linux'
         working-directory: usgslatex/usgsLaTeX
         run: sudo ./install.sh --all-users
-
-      - name: Install dependencies for ex-gwf-twri example model
-        if: runner.os == 'Linux'
-        working-directory: modflow6-examples/etc
-        run: |
-          # install extra Python packages
-          pip install -r requirements.pip.txt
-
-          # the example model needs executables to be on the path
-          echo "${{ github.workspace }}/modflow6/bin" >> $GITHUB_PATH
-          echo "${{ github.workspace }}/modflow6/bin/downloaded" >> $GITHUB_PATH
-
-      - name: Build ex-gwf-twri example model
-        if: runner.os == 'Linux'
-        working-directory: modflow6-examples/scripts
-        run: python ex-gwf-twri.py
-
+     
       - name: Test distribution scripts
         working-directory: modflow6/distribution
         env:
           GITHUB_TOKEN: ${{ github.token }}
         run: pytest -v --durations 0
 
-  test_gfortran_previous:
-    name: Test gfortran (${{ matrix.GCC_V }}, ${{ matrix.os }})
+  test_intel_fortran:
+    name: Test intel fortran
     needs:
       - lint
       - build
@@ -263,90 +301,23 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ ubuntu-20.04 ]
-        GCC_V: [ 7, 8, 9, 10, 11 ]
-    defaults:
-      run:
-        shell: bash -l {0}
-    env:
-      FC: gfortran
-    steps:
-
-      - name: Checkout modflow6
-        uses: actions/checkout@v3
-        with:
-          path: modflow6
-
-      - name: Checkout modflow6-testmodels
-        uses: actions/checkout@v3
-        with:
-          repository: MODFLOW-USGS/modflow6-testmodels
-          path: modflow6-testmodels
-
-      - name: Setup GNU Fortran ${{ matrix.GCC_V }}
-        uses: awvwgk/setup-fortran@main
-        with:
-          compiler: gcc
-          version: ${{ matrix.GCC_V }}
-
-      - name: Setup Micromamba
-        uses: mamba-org/setup-micromamba@v1
-        with:
-          environment-file: modflow6/environment.yml
-          cache-downloads: true
-          cache-environment: true
-
-      - name: Update flopy
-        working-directory: modflow6/autotest
-        run: python update_flopy.py
-
-      - name: Build modflow6
-        working-directory: modflow6
-        run: |
-          meson setup builddir -Ddebug=false --prefix=$(pwd) --libdir=bin
-          meson install -C builddir
-          meson test --verbose --no-rebuild -C builddir
-      
-      - name: Get executables
-        working-directory: modflow6/autotest
-        env:
-          GITHUB_TOKEN: ${{ github.token }}
-        run: pytest -v --durations 0 get_exes.py
-
-      - name: Test modflow6
-        working-directory: modflow6/autotest
-        env:
-          REPOS_PATH: ${{ github.workspace }}
-        run: |
-          if [ "${{ github.ref_name }}" == "master" ]; then
-            pytest -v -n auto --durations 0 -m "not large and not developmode"
-          else
-            pytest -v -n auto --durations 0 -m "not large"
-          fi
+        include:
+          - {os: ubuntu-22.04, compiler: intel-classic, version: 2021.7}
+          - {os: macos-12, compiler: intel-classic, version: 2021.7}
+          - {os: windows-2022, compiler: intel-classic, version: 2021.7}
 
-  test_ifort:
-    name: Test (ifort)
-    needs:
-      - lint
-      - build
-      - smoke_test
-    runs-on: ${{ matrix.os }}
-    strategy:
-      fail-fast: false
-      matrix:
-        os: [ ubuntu-latest, macos-latest, windows-latest ]
     defaults:
       run:
         shell: bash -l {0}
     steps:
 
       - name: Checkout modflow6
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           path: modflow6
 
       - name: Checkout modflow6-testmodels
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: MODFLOW-USGS/modflow6-testmodels
           path: modflow6-testmodels
@@ -362,50 +333,41 @@ jobs:
           cache-downloads: true
 
       - name: Setup Intel Fortran
-        uses: modflowpy/install-intelfortran-action@v1
+        uses: fortran-lang/setup-fortran@v1
+        with:
+          compiler: ${{ matrix.compiler }}
+          version: ${{ matrix.version }}
 
       - name: Update version files
         working-directory: modflow6/distribution
         run: python update_version.py
 
       - name: Build modflow6
-        if: runner.os != 'Windows'
         working-directory: modflow6
         run: |
           meson setup builddir -Ddebug=false --prefix=$(pwd) --libdir=bin
           meson install -C builddir
-          meson test --verbose --no-rebuild -C builddir
 
-      - name: Build modflow6 (Windows)
-        if: runner.os == 'Windows'
+      - name: Show build log
+        if: failure()
         working-directory: modflow6
-        shell: pwsh
-        run: |
-          meson setup builddir -Ddebug=false --prefix=$(pwd) --libdir=bin
-          meson install -C builddir
-          meson test --verbose --no-rebuild -C builddir
+        run: cat builddir/meson-logs/meson-log.txt
+
+      - name: Unit test programs
+        working-directory: modflow6
+        run: meson test --verbose --no-rebuild -C builddir
 
       - name: Update flopy
         working-directory: modflow6/autotest
         run: python update_flopy.py
 
       - name: Get executables
-        if: runner.os != 'Windows'
         working-directory: modflow6/autotest
         env:
           GITHUB_TOKEN: ${{ github.token }}
         run: pytest -v --durations 0 get_exes.py
-          
-      - name: Get executables (Windows)
-        if: runner.os == 'Windows'
-        working-directory: modflow6/autotest
-        shell: pwsh
-        env:
-          GITHUB_TOKEN: ${{ github.token }}
-        run: pytest -v --durations 0 get_exes.py
 
       - name: Test programs
-        if: runner.os != 'Windows'
         working-directory: modflow6/autotest
         env:
           REPOS_PATH: ${{ github.workspace }}
@@ -416,30 +378,8 @@ jobs:
             pytest -v -n auto --durations 0 -m "not large"
           fi
 
-      - name: Test programs (Windows)
-        if: runner.os == 'Windows'
-        working-directory: modflow6/autotest
-        shell: pwsh
-        env:
-          REPOS_PATH: ${{ github.workspace }}
-        run: |
-          if ( "${{ github.ref_name }}" -eq "master" ) {
-            pytest -v -n auto --durations 0 -m "not large and not developmode"
-          } else {
-            pytest -v -n auto --durations 0 -m "not large"
-          }
-
       - name: Test scripts
-        if: runner.os != 'Windows'
-        working-directory: modflow6/distribution
-        env:
-          GITHUB_TOKEN: ${{ github.token }}
-        run: pytest -v --durations 0
-
-      - name: Test scripts (Windows)
-        if: runner.os == 'Windows'
         working-directory: modflow6/distribution
-        shell: pwsh
         env:
           GITHUB_TOKEN: ${{ github.token }}
         run: pytest -v --durations 0
@@ -464,7 +404,7 @@ jobs:
     steps:
 
       - name: Checkout modflow6
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           path: modflow6
 
@@ -488,14 +428,14 @@ jobs:
           mpi: msmpi
 
       - name: Setup GNU Fortran ${{ env.GCC_V }}
-        uses: awvwgk/setup-fortran@main
+        uses: fortran-lang/setup-fortran@v1
         with:
           compiler: gcc
           version: ${{ env.GCC_V }}
 
       - name: Cache PETSc
         id: cache-petsc
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: petsc
           key: ${{ runner.os }}-petsc
diff --git a/.github/workflows/compilers.yml b/.github/workflows/compilers.yml
new file mode 100644
index 00000000000..e3fcd7dd85b
--- /dev/null
+++ b/.github/workflows/compilers.yml
@@ -0,0 +1,366 @@
+name: MODFLOW 6 compiler checks
+on:
+  push:
+    branches:
+      - v[0-9]+.[0-9]+.[0-9]+*
+      - master
+  pull_request:
+    branches:
+      - master
+  schedule:
+    - cron: 0 0 * * 0 # 12am utc every sunday
+  # workflow_dispatch trigger to start release via GitHub UI or CLI, see
+  # https://docs.github.com/en/actions/managing-workflow-runs/manually-running-a-workflow
+  workflow_dispatch:
+jobs:
+  test:
+    name: Test
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        # combinations from https://github.com/fortran-lang/setup-fortran#runner-compatibility
+        include:
+          # gfortran
+          - {os: ubuntu-20.04, compiler: gcc, version: 7}
+          - {os: ubuntu-20.04, compiler: gcc, version: 8}
+          - {os: ubuntu-20.04, compiler: gcc, version: 9}
+          - {os: ubuntu-20.04, compiler: gcc, version: 10}
+          - {os: ubuntu-20.04, compiler: gcc, version: 11}
+          - {os: ubuntu-22.04, compiler: gcc, version: 9}
+          - {os: ubuntu-22.04, compiler: gcc, version: 10}
+          - {os: ubuntu-22.04, compiler: gcc, version: 11}
+          - {os: ubuntu-22.04, compiler: gcc, version: 12}
+          - {os: ubuntu-22.04, compiler: gcc, version: 13}
+          - {os: macos-11, compiler: gcc, version: 7}
+          - {os: macos-11, compiler: gcc, version: 8}
+          - {os: macos-11, compiler: gcc, version: 9}
+          - {os: macos-11, compiler: gcc, version: 10}
+          - {os: macos-11, compiler: gcc, version: 11}
+          - {os: macos-11, compiler: gcc, version: 12}
+          - {os: macos-11, compiler: gcc, version: 13}
+          - {os: macos-12, compiler: gcc, version: 7}
+          - {os: macos-12, compiler: gcc, version: 8}
+          - {os: macos-12, compiler: gcc, version: 9}
+          - {os: macos-12, compiler: gcc, version: 10}
+          - {os: macos-12, compiler: gcc, version: 11}
+          - {os: macos-12, compiler: gcc, version: 12}
+          - {os: macos-12, compiler: gcc, version: 13}
+          - {os: windows-2019, compiler: gcc, version: 9}
+          - {os: windows-2019, compiler: gcc, version: 10}
+          - {os: windows-2019, compiler: gcc, version: 11}
+          - {os: windows-2019, compiler: gcc, version: 12}
+          - {os: windows-2019, compiler: gcc, version: 13}
+          - {os: windows-2022, compiler: gcc, version: 9}
+          - {os: windows-2022, compiler: gcc, version: 10}
+          - {os: windows-2022, compiler: gcc, version: 11}
+          - {os: windows-2022, compiler: gcc, version: 12}
+          - {os: windows-2022, compiler: gcc, version: 13}
+          # ifx
+          - {os: ubuntu-20.04, compiler: intel, version: 2023.2}
+          - {os: ubuntu-20.04, compiler: intel, version: 2023.1}
+          - {os: ubuntu-20.04, compiler: intel, version: "2023.0"}
+          - {os: ubuntu-20.04, compiler: intel, version: 2022.2.1}
+          - {os: ubuntu-20.04, compiler: intel, version: 2022.2}
+          - {os: ubuntu-20.04, compiler: intel, version: 2022.1}
+          - {os: ubuntu-20.04, compiler: intel, version: "2022.0"}
+          - {os: ubuntu-20.04, compiler: intel, version: 2021.4}
+          - {os: ubuntu-20.04, compiler: intel, version: 2021.2}
+          - {os: ubuntu-20.04, compiler: intel, version: 2021.1}
+          - {os: ubuntu-22.04, compiler: intel, version: 2023.2}
+          - {os: ubuntu-22.04, compiler: intel, version: 2023.1}
+          - {os: ubuntu-22.04, compiler: intel, version: "2023.0"}
+          - {os: ubuntu-22.04, compiler: intel, version: 2022.2.1}
+          - {os: ubuntu-22.04, compiler: intel, version: 2022.2}
+          - {os: ubuntu-22.04, compiler: intel, version: 2022.1}
+          - {os: ubuntu-22.04, compiler: intel, version: "2022.0"}
+          - {os: ubuntu-22.04, compiler: intel, version: 2021.4}
+          - {os: ubuntu-22.04, compiler: intel, version: 2021.2}
+          - {os: ubuntu-22.04, compiler: intel, version: 2021.1}
+          # no ifx on mac
+          - {os: windows-2019, compiler: intel, version: 2023.2}
+          - {os: windows-2019, compiler: intel, version: 2023.1}
+          - {os: windows-2019, compiler: intel, version: "2023.0"}
+          - {os: windows-2019, compiler: intel, version: 2022.2}
+          - {os: windows-2019, compiler: intel, version: 2022.1}
+          - {os: windows-2022, compiler: intel, version: 2023.2}
+          - {os: windows-2022, compiler: intel, version: 2023.1}
+          - {os: windows-2022, compiler: intel, version: "2023.0"}
+          - {os: windows-2022, compiler: intel, version: 2022.2}
+          - {os: windows-2022, compiler: intel, version: 2022.1}
+          # ifort
+          - {os: ubuntu-20.04, compiler: intel-classic, version: "2021.10"}
+          - {os: ubuntu-20.04, compiler: intel-classic, version: 2021.9}
+          - {os: ubuntu-20.04, compiler: intel-classic, version: 2021.8}
+          - {os: ubuntu-20.04, compiler: intel-classic, version: 2021.7}
+          - {os: ubuntu-20.04, compiler: intel-classic, version: 2021.6}
+          - {os: ubuntu-20.04, compiler: intel-classic, version: 2021.5}
+          - {os: ubuntu-20.04, compiler: intel-classic, version: 2021.4}
+          - {os: ubuntu-20.04, compiler: intel-classic, version: 2021.3}
+          - {os: ubuntu-20.04, compiler: intel-classic, version: 2021.2}
+          - {os: ubuntu-20.04, compiler: intel-classic, version: 2021.1}
+          - {os: ubuntu-22.04, compiler: intel-classic, version: "2021.10"}
+          - {os: ubuntu-22.04, compiler: intel-classic, version: 2021.9}
+          - {os: ubuntu-22.04, compiler: intel-classic, version: 2021.8}
+          - {os: ubuntu-22.04, compiler: intel-classic, version: 2021.7}
+          - {os: ubuntu-22.04, compiler: intel-classic, version: 2021.6}
+          - {os: ubuntu-22.04, compiler: intel-classic, version: 2021.5}
+          - {os: ubuntu-22.04, compiler: intel-classic, version: 2021.4}
+          - {os: ubuntu-22.04, compiler: intel-classic, version: 2021.3}
+          - {os: ubuntu-22.04, compiler: intel-classic, version: 2021.2}
+          - {os: ubuntu-22.04, compiler: intel-classic, version: 2021.1}
+          - {os: macos-11, compiler: intel-classic, version: "2021.10"}
+          - {os: macos-11, compiler: intel-classic, version: 2021.9}
+          - {os: macos-11, compiler: intel-classic, version: 2021.8}
+          - {os: macos-11, compiler: intel-classic, version: 2021.7}
+          - {os: macos-11, compiler: intel-classic, version: 2021.6}
+          - {os: macos-11, compiler: intel-classic, version: 2021.5}
+          - {os: macos-11, compiler: intel-classic, version: 2021.4}
+          - {os: macos-11, compiler: intel-classic, version: 2021.3}
+          - {os: macos-11, compiler: intel-classic, version: 2021.2}
+          - {os: macos-11, compiler: intel-classic, version: 2021.1}
+          - {os: macos-12, compiler: intel-classic, version: "2021.10"}
+          - {os: macos-12, compiler: intel-classic, version: 2021.9}
+          - {os: macos-12, compiler: intel-classic, version: 2021.8}
+          - {os: macos-12, compiler: intel-classic, version: 2021.7}
+          - {os: macos-12, compiler: intel-classic, version: 2021.6}
+          - {os: macos-12, compiler: intel-classic, version: 2021.5}
+          - {os: macos-12, compiler: intel-classic, version: 2021.4}
+          - {os: macos-12, compiler: intel-classic, version: 2021.3}
+          - {os: macos-12, compiler: intel-classic, version: 2021.2}
+          - {os: macos-12, compiler: intel-classic, version: 2021.1}
+          - {os: windows-2019, compiler: intel-classic, version: "2021.10"}
+          - {os: windows-2019, compiler: intel-classic, version: 2021.9}
+          - {os: windows-2019, compiler: intel-classic, version: 2021.8}
+          - {os: windows-2019, compiler: intel-classic, version: 2021.7}
+          - {os: windows-2019, compiler: intel-classic, version: 2021.6}
+          - {os: windows-2022, compiler: intel-classic, version: "2021.10"}
+          - {os: windows-2022, compiler: intel-classic, version: 2021.9}
+          - {os: windows-2022, compiler: intel-classic, version: 2021.8}
+          - {os: windows-2022, compiler: intel-classic, version: 2021.7}
+          - {os: windows-2022, compiler: intel-classic, version: 2021.6}
+    defaults:
+      run:
+        shell: bash -l {0}
+    steps:
+      - name: Checkout modflow6
+        uses: actions/checkout@v4
+        with:
+          path: modflow6
+
+      - name: Checkout modflow6-testmodels
+        uses: actions/checkout@v4
+        with:
+          repository: MODFLOW-USGS/modflow6-testmodels
+          path: modflow6-testmodels
+    
+      - name: Checkout modflow6-examples
+        uses: actions/checkout@v4
+        with:
+          repository: MODFLOW-USGS/modflow6-examples
+          path: modflow6-examples
+    
+      - name: Setup ${{ matrix.compiler }} ${{ matrix.version }}
+        uses: fortran-lang/setup-fortran@v1
+        with:
+          compiler: ${{ matrix.compiler}}
+          version: ${{ matrix.version }}
+
+      - name: Setup Micromamba
+        uses: mamba-org/setup-micromamba@v1
+        with:
+          environment-file: modflow6/environment.yml
+          init-shell: >-
+              bash
+              powershell
+          cache-environment: true
+          cache-downloads: true
+
+      - name: Build modflow6
+        working-directory: modflow6
+        run: |
+          meson setup builddir -Ddebug=false --prefix=$(pwd) --libdir=bin
+          meson install -C builddir
+
+      - name: Show build log
+        if: failure()
+        working-directory: modflow6
+        run: cat builddir/meson-logs/meson-log.txt
+      
+      - name: Upload build log
+        if: failure()
+        uses: actions/upload-artifact@v3
+        with:
+          name: meson-log.txt
+          path: modflow6/builddir/meson-logs/meson-log.txt
+    
+      - name: Unit test programs
+        if: success()
+        working-directory: modflow6
+        run: meson test --verbose --no-rebuild -C builddir
+
+      - name: Create compile report
+        if: success() || failure()
+        shell: bash
+        run: |
+          if [[ "${{ job.status }}" == "success" ]]; then
+            support="&check;"
+          else
+            support=""
+          fi
+          
+          mkdir -p compat
+          prefix="${{ matrix.os }},${{ matrix.compiler }},${{ matrix.version }}"
+          echo "$prefix,$support" >> "compat/comp_${prefix//,/_}.csv"
+
+      - name: Update flopy
+        if: success()
+        working-directory: modflow6/autotest
+        run: python update_flopy.py
+
+      - name: Get executables
+        if: success()
+        working-directory: modflow6/autotest
+        env:
+          GITHUB_TOKEN: ${{ github.token }}
+        run: pytest -v --durations 0 get_exes.py
+
+      - name: Test modflow6
+        if: success()
+        working-directory: modflow6/autotest
+        env:
+          REPOS_PATH: ${{ github.workspace }}
+        run: pytest -v -n auto --durations 0
+    
+      - name: Create test report
+        if: success() || failure()
+        shell: bash
+        run: |
+          if [[ "${{ job.status }}" == "success" ]]; then
+            support="&check;"
+          else
+            support=""
+          fi
+          
+          mkdir -p compat
+          prefix="${{ matrix.os }},${{ matrix.compiler }},${{ matrix.version }}"
+          echo "$prefix,$support" >> "compat/test_${prefix//,/_}.csv"
+
+      - name: Upload reports
+        if: success() || failure()
+        uses: actions/upload-artifact@v3
+        with:
+          name: compat
+          path: compat/*.csv
+
+  report:
+    name: Make compatibility report
+    if: success() || failure()
+    needs: test
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
+    steps:
+
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: 3.9
+
+      - name: Install packages
+        run: pip install tabulate pandas
+
+      - name: Download reports
+        uses: actions/download-artifact@v3
+        with:
+          name: compat
+          path: .github/compat/new
+
+      - name: Concatenate reports
+        working-directory: .github/compat
+        run: |
+          cols="runner,compiler,version,support"
+          echo "$cols" > long_comp.csv
+          echo "$cols" > long_test.csv
+          cat new/comp*.csv >> long_comp.csv
+          cat new/test*.csv >> long_test.csv
+
+      - name: Make wide CSV and MD tables
+        working-directory: .github/compat
+        id: merge-reports
+        run: |
+          python ../common/wide_compat_reports.py "long_comp.csv" "comp.csv"
+          python ../common/wide_compat_reports.py "long_test.csv" "test.csv"
+
+      # only upload wide CSVs and Markdown tables
+      - name: Upload artifacts
+        uses: actions/upload-artifact@v3
+        with:
+          name: compat
+          path: |
+            .github/compat/comp.*
+            .github/compat/test.*
+
+      # update DEVELOPER.md if this is not a push event and there are any changes
+      - name: Check for changes
+        working-directory: .github/compat
+        if: github.event_name != 'pull_request'
+        id: diff
+        run: |
+          if ! [ -f comp.csv ]; then
+            echo "diff=false" >> $GITHUB_OUTPUT
+            exit 0
+          fi
+
+          diff_comp=$(git diff comp.csv)
+          diff_test=$(git diff test.csv)
+          if [[ ( $diff_comp == "" ) && ( $diff_test == "" ) ]]; then
+            echo "No changes found"
+            echo "diff=false" >> $GITHUB_OUTPUT
+          else
+            echo "comp.csv diff:"
+            echo "$diff_comp"
+            echo "test.csv diff:"
+            echo "$diff_test"
+            echo "diff=true" >> $GITHUB_OUTPUT
+          fi
+    
+      - name: Update DEVELOPER.md
+        if: ${{ steps.diff.outputs.diff == 'true' && github.event_name != 'pull_request' }}
+        run: |
+          python .github/common/update_compat_tables.py "compile" ".github/compat/comp.md" "DEVELOPER.md"
+          python .github/common/update_compat_tables.py "test" ".github/compat/test.md" "DEVELOPER.md"
+          
+      - name: Print DEVELOPER.md diff
+        if: ${{ steps.diff.outputs.diff == 'true' && github.event_name != 'pull_request' }}
+        run: git diff DEVELOPER.md
+
+      - name: Create pull request
+        if: ${{ steps.diff.outputs.diff == 'true' && github.event_name != 'pull_request' }}
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          # one at a time
+          head="compat"
+          id=$(gh pr list -H $head -s open --json id -q ".[0].id")
+          [[ -n "${id// /}" ]] && (echo "PR already open"; exit 0) || (echo "opening PR")
+
+          # setup bot user
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+
+          # create new branch
+          git switch -c "$head"
+
+          # commit and push
+          git add DEVELOPER.md .github/compat/comp.csv .github/compat/test.csv
+          git commit -m "Update compatibility tables"
+          git push -u origin "$head"
+
+          # open PR
+          cat <(echo '### Compile') <(echo) .github/compat/comp.md <(echo) <(echo '### Test') <(echo) .github/compat/test.md > compat.md
+          gh pr create -B "${{ github.event.repository.default_branch }}" -H "$head" --title "Update compile/test compatibility tables" --body-file compat.md
\ No newline at end of file
diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index 1da492fc9c5..35f630e6bc5 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -1,18 +1,16 @@
 name: MODFLOW 6 documentation
 on:
   push:
-    branches:
-      - master
-      - develop
-      - ci-diagnose*
     paths-ignore:
       - '.github/workflows/release.yml'
+      - '.hpc/**'
   pull_request:
     branches:
       - master
       - develop
     paths-ignore:
       - '.github/workflows/release.yml'
+      - '.hpc/**'
 jobs:
   rtd_build:
     name: Build ReadTheDocs
@@ -25,18 +23,18 @@ jobs:
 
     steps:
       - name: Checkout modflow6
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           path: modflow6
 
       - name: Checkout modflow6-examples
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: MODFLOW-USGS/modflow6-examples
           path: modflow6-examples
 
       - name: Checkout usgslatex
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: MODFLOW-USGS/usgslatex
           path: usgslatex
@@ -69,14 +67,14 @@ jobs:
         run: pytest -v build_mfio_tex.py
 
       - name: Setup GNU Fortran ${{ env.GCC_V }}
-        uses: awvwgk/setup-fortran@main
+        uses: fortran-lang/setup-fortran@v1
         with:
           compiler: gcc
           version: ${{ env.GCC_V }}
 
       - name: Cache modflow6 examples
         id: cache-examples
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: modflow6-examples/examples
           key: modflow6-examples-${{ hashFiles('modflow6-examples/scripts/**') }}
@@ -95,9 +93,9 @@ jobs:
 
       - name: Build example models
         if: steps.cache-examples.outputs.cache-hit != 'true'
-        working-directory: modflow6-examples/etc
+        working-directory: modflow6-examples/autotest
         run: |
-          python ci_build_files.py
+          pytest -v -n auto test_scripts.py --init
           ls -lh ../examples/
 
       - name: Run benchmarks
@@ -105,21 +103,35 @@ jobs:
         run: python benchmark.py
         env:
           GITHUB_TOKEN: ${{ github.token }}
-
-      - name: Run sphinx
-        working-directory: modflow6/.build_rtd_docs
-        run: make html
-
+      
       - name: Show benchmarks
         working-directory: modflow6/distribution
         run: cat run-time-comparison.md
-
+    
       - name: Upload benchmarks
         uses: actions/upload-artifact@v3
         with:
           name: run-time-comparison
           path: modflow6/distribution/run-time-comparison.md
 
+      - name: Collect deprecations
+        working-directory: modflow6/doc/mf6io/mf6ivar
+        run: python deprecations.py
+
+      - name: Show deprecations
+        working-directory: modflow6/doc/mf6io/mf6ivar/md
+        run: cat deprecations.md
+
+      - name: Upload deprecations
+        uses: actions/upload-artifact@v3
+        with:
+          name: deprecations
+          path: modflow6/doc/mf6io/mf6ivar/md/deprecations.md
+
+      - name: Run sphinx
+        working-directory: modflow6/.build_rtd_docs
+        run: make html
+      
       - name: Upload results
         uses: actions/upload-artifact@v3
         with:
@@ -139,7 +151,7 @@ jobs:
     if: github.repository_owner == 'MODFLOW-USGS' && github.event_name == 'push'
     steps:
       - name: Checkout repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Trigger RTDs build on push to repo branches
         uses: dfm/rtds-action@v1
@@ -160,7 +172,7 @@ jobs:
         shell: bash -l {0}
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Print branch name
         run: echo ${{env.branch-name}}
@@ -208,7 +220,7 @@ jobs:
         working-directory: ${{env.working-directory}}
       
       - name: upload pages artifact
-        uses: actions/upload-pages-artifact@v1
+        uses: actions/upload-pages-artifact@v2
         with:
           path: ${{env.working-directory}}/html
 
@@ -225,4 +237,4 @@ jobs:
     steps:
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v2
+        uses: actions/deploy-pages@v3
diff --git a/.github/workflows/large.yml b/.github/workflows/large.yml
index 291dcc16673..e9cf36c98c5 100644
--- a/.github/workflows/large.yml
+++ b/.github/workflows/large.yml
@@ -3,38 +3,53 @@ on:
   schedule:
     - cron: '0 6 * * *' # run at 6 AM UTC every day
 jobs:
+  # caching only necessary on Windows
   cache_ifort:
     name: Cache Intel OneAPI compilers
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
       matrix:
-        os: [ ubuntu-22.04, macos-12, windows-2022 ]
+        include:
+          # ifx
+          - {os: windows-2022, compiler: intel, version: 2022.2}
+          # ifort
+          - {os: windows-2022, compiler: intel-classic, version: "2021.10"}
+          - {os: windows-2022, compiler: intel-classic, version: 2021.9}
+          - {os: windows-2022, compiler: intel-classic, version: 2021.8}
+          - {os: windows-2022, compiler: intel-classic, version: 2021.7}
+          - {os: windows-2022, compiler: intel-classic, version: 2021.6}
     steps:
-      - name: Setup Intel Fortran
-        uses: modflowpy/install-intelfortran-action@v1
+      - name: Setup ${{ matrix.compiler }} ${{ matrix.version }}
+        uses: fortran-lang/setup-fortran@v1
+        with:
+          compiler: ${{ matrix.compiler }}
+          version: ${{ matrix.version }}
   test:
     name: Test
     runs-on: ubuntu-22.04
     strategy:
       fail-fast: false
       matrix:
-        fc: [ ifort, gfortran ]
-        repo: [ examples, largetestmodels ]
+        include:
+          - {compiler: gcc, version: 13, repo: examples}
+          - {compiler: gcc, version: 13, repo: largetestmodels}
+          - {compiler: intel, version: 2022.2.1, repo: examples}
+          - {compiler: intel, version: 2022.2.1, repo: largetestmodels}
+          - {compiler: intel-classic, version: 2021.6, repo: examples}
+          - {compiler: intel-classic, version: 2021.6, repo: largetestmodels}
     defaults:
       run:
         shell: bash -l {0}
-    env:
-      GCC_V: 12
     steps:
 
       - name: Checkout modflow6
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           path: modflow6
 
       - name: Checkout modflow6-${{ matrix.repo }}
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: MODFLOW-USGS/modflow6-${{ matrix.repo }}
           path: modflow6-${{ matrix.repo }}
@@ -46,20 +61,15 @@ jobs:
           cache-downloads: true
           cache-environment: true
 
-      - name: Setup gfortran ${{ env.GCC_V }}
-        if: matrix.FC == 'gfortran'
-        uses: awvwgk/setup-fortran@main
+      - name: Setup compilers (${{ matrix.compiler }} ${{ matrix.version }})
+        uses: fortran-lang/setup-fortran@v1
         with:
-          compiler: gcc
-          version: ${{ env.GCC_V }}
-
-      - name: Setup ifort
-        if: matrix.fc == 'ifort'
-        uses: modflowpy/install-intelfortran-action@v1
+          compiler: ${{ matrix.compiler }}
+          version: ${{ matrix.version }}
 
       - name: Cache modflow6 examples
         id: cache-examples
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: modflow6-examples/examples
           key: modflow6-examples-${{ hashFiles('modflow6-examples/scripts/**') }}
@@ -72,9 +82,9 @@ jobs:
 
       - name: Build example models
         if: matrix.repo == 'examples' && steps.cache-examples.outputs.cache-hit != 'true'
-        working-directory: modflow6-examples/etc
+        working-directory: modflow6-examples/autotest
         run: |
-          python ci_build_files.py
+          pytest -v -n auto test_scripts.py --init
           ls -lh ../examples/
 
       - name: Add Micromamba Scripts dir to path (Windows)
@@ -103,4 +113,4 @@ jobs:
 
       - name: Run tests
         working-directory: modflow6/autotest
-        run: pytest -v -n auto --durations 0 test_z03_${{ matrix.repo }}.py
\ No newline at end of file
+        run: pytest -v -n auto --durations 0 test_${{ matrix.repo }}.py
\ No newline at end of file
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 1973766a474..527952f547c 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -13,6 +13,16 @@ on:
         description: 'Branch to release from.'
         required: true
         type: string
+      compiler_toolchain:
+        description: 'Compiler toolchain to use. For supported options see https://github.com/MODFLOW-USGS/modflow6/blob/develop/DEVELOPER.md#compiler-compatibility.'
+        required: false
+        type: string
+        default: 'intel-classic'
+      compiler_version:
+        description: 'Compiler version to use. For supported options see https://github.com/MODFLOW-USGS/modflow6/blob/develop/DEVELOPER.md#compiler-compatibility.'
+        required: false
+        type: string
+        default: '2021.7'
       developmode:
         description: 'Build binaries in develop mode. If false, IDEVELOPMODE is set to 0.'
         required: false
@@ -68,7 +78,7 @@ jobs:
       distname: ${{ steps.set_version.outputs.distname }}
     steps:
       - name: Checkout modflow6
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: ${{ github.repository_owner }}/modflow6
           path: modflow6
@@ -84,8 +94,11 @@ jobs:
             bash
             powershell
 
-      - name: Setup Intel Fortran
-        uses: modflowpy/install-intelfortran-action@v1
+      - name: Setup ${{ inputs.compiler_toolchain }} ${{ inputs.compiler_version }}
+        uses: fortran-lang/setup-fortran@v1
+        with:
+          compiler: ${{ inputs.compiler_toolchain }}
+          version: ${{ inputs.compiler_version }}
 
       - name: Set version number
         id: set_version
@@ -139,14 +152,14 @@ jobs:
       # only run steps below if inputs.run_tests is true
       - name: Checkout modflow6-testmodels
         if: inputs.run_tests == true
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: MODFLOW-USGS/modflow6-testmodels
           path: modflow6-testmodels
 
       - name: Checkout modflow6-examples
         if: inputs.run_tests == true
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: MODFLOW-USGS/modflow6-examples
           path: modflow6-examples
@@ -192,7 +205,7 @@ jobs:
       # compiling binaries, building documentation
       - name: Checkout usgslatex
         if: ${{ runner.os == 'Linux' && inputs.run_tests == true }}
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: MODFLOW-USGS/usgslatex
           path: usgslatex
@@ -212,22 +225,6 @@ jobs:
         working-directory: usgslatex/usgsLaTeX
         run: sudo ./install.sh --all-users
 
-      - name: Install dependencies for ex-gwf-twri example model
-        if: ${{ runner.os == 'Linux' && inputs.run_tests == true }}
-        working-directory: modflow6-examples/etc
-        run: |
-          # install extra Python packages
-          pip install -r requirements.pip.txt
-
-          # the example model needs executables to be on the path
-          echo "${{ github.workspace }}/modflow6/bin" >> $GITHUB_PATH
-          echo "${{ github.workspace }}/modflow6/bin/downloaded" >> $GITHUB_PATH
-
-      - name: Build ex-gwf-twri example model
-        if: ${{ runner.os == 'Linux' && inputs.run_tests == true }}
-        working-directory: modflow6-examples/scripts
-        run: python ex-gwf-twri.py
-
       - name: Test distribution scripts
         if: ${{ inputs.run_tests == true }}
         working-directory: modflow6/distribution
@@ -245,20 +242,20 @@ jobs:
     steps:
 
       - name: Checkout modflow6
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: ${{ github.repository_owner }}/modflow6
           path: modflow6
           ref: ${{ inputs.branch }}
 
       - name: Checkout modflow6-examples
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: MODFLOW-USGS/modflow6-examples
           path: modflow6-examples
 
       - name: Checkout usgslatex
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: MODFLOW-USGS/usgslatex
           path: usgslatex
@@ -283,8 +280,11 @@ jobs:
           cache-downloads: true
           cache-environment: true
 
-      - name: Setup Intel Fortran
-        uses: modflowpy/install-intelfortran-action@v1
+      - name: Setup ${{ inputs.compiler_toolchain }} ${{ inputs.compiler_version }}
+        uses: fortran-lang/setup-fortran@v1
+        with:
+          compiler: ${{ inputs.compiler_toolchain }}
+          version: ${{ inputs.compiler_version }}
 
       - name: Update version
         id: update_version
@@ -300,51 +300,44 @@ jobs:
           fi
           eval "$cmd"
 
+      - name: Update FloPy classes
+        working-directory: modflow6/autotest
+        run: python update_flopy.py
+
       - name: Download pre-built binaries
         uses: actions/download-artifact@v3
         with:
           name: bin-${{ runner.os }}
           path: bin
+
+      # execute permissions may not have survived artifact upload/download
+      - name: Set executable permissions
+        working-directory: modflow6-examples/etc
+        run: |
+          chmod +x "${{ github.workspace }}/bin/mf6"
+          chmod +x "${{ github.workspace }}/bin/mf5to6"
+          chmod +x "${{ github.workspace }}/bin/zbud6"
     
       - name: Install dependencies for building models
+        if: inputs.full == true
         working-directory: modflow6-examples/etc
         env:
           GITHUB_TOKEN: ${{ github.token }}
         run: |
-          # install extra Python packages
           pip install -r requirements.pip.txt
-  
-          # the example model needs executables to be on the path
           echo "${{ github.workspace }}/bin" >> $GITHUB_PATH
-
-          # execute permissions may not have survived artifact upload/download
-          chmod +x "${{ github.workspace }}/bin/mf6"
-          chmod +x "${{ github.workspace }}/bin/mf5to6"
-          chmod +x "${{ github.workspace }}/bin/zbud6"
-
-          # the example model also needs mf2005
           get-modflow "${{ github.workspace }}/bin" --subset mf2005,triangle,gridgen
-  
-      - name: Update FloPy
-        working-directory: modflow6/autotest
-        run: python update_flopy.py
-
-      - name: Build ex-gwf-twri example model
-        if: inputs.full != true
-        working-directory: modflow6-examples/scripts
-        run: python ex-gwf-twri.py
 
       - name: Build example models
         if: inputs.full == true
-        working-directory: modflow6-examples/etc
-        run: python ci_build_files.py
+        working-directory: modflow6-examples/autotest
+        run: pytest -v -n auto test_scripts.py --init
       
-      - name: Create full docs folder structure
+      - name: Create folder structure
         if: inputs.full == true
         run: |
+          # Create empty folder structure for the <distname>/docs subdirectory
           distname=${{ needs.build.outputs.distname }}
-
-          # Create a skeleton of the distribution's folder structure to include in the docs
           mkdir -p "$distname/doc"
           mkdir "$distname/make"
           mkdir "$distname/msvs"
@@ -353,19 +346,34 @@ jobs:
           cp modflow6/meson.build "$distname/meson.build"
           cp -r modflow6-examples/examples "$distname"
           cp -r modflow6/src "$distname"
-          cp -r modflow6/utils "$distname"
+          cp -r modflow6/utils/mf5to6 "$distname/utils/mf5to6"
+          cp -r modflow6/utils/zonebudget "$distname/utils/zonebudget"
           
           # create LaTeX file describing the folder structure
           cd modflow6/doc/ReleaseNotes
           python mk_folder_struct.py -dp "${{ github.workspace }}/$distname"
 
+      - name: Collect deprecations
+        working-directory: modflow6/doc/mf6io/mf6ivar
+        run: |
+          python deprecations.py
+          cat md/deprecations.md
+
+      - name: Upload deprecations
+        uses: actions/upload-artifact@v3
+        with:
+          name: deprecations
+          path: modflow6/doc/mf6io/mf6ivar/md/deprecations.md
+
       - name: Build documentation
         env:
-          # need a GITHUB_TOKEN to download example doc PDF asset from modflow6-examples repo
+          # this step is lazy about building the mf6 examples PDF document, first
+          # trying to download a prebuilt PDF from MODFLOW-USGS/modflow6-examples,
+          # so it needs a GITHUB_TOKEN.
           GITHUB_TOKEN: ${{ github.token }}
         run: |
           mkdir -p "${{ needs.build.outputs.distname }}/doc"
-          cmd="python modflow6/distribution/build_docs.py -b bin -o doc -e modflow6-examples"
+          cmd="python modflow6/distribution/build_docs.py -b bin -o doc"
           if [[ "${{ inputs.full }}" == "true" ]]; then
             cmd="$cmd --full"
           fi
@@ -399,14 +407,14 @@ jobs:
         shell: bash -l {0}
     steps:
       - name: Checkout modflow6
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: ${{ github.repository_owner }}/modflow6
           path: modflow6
           ref: ${{ inputs.branch }}
 
       - name: Checkout modflow6-examples
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: MODFLOW-USGS/modflow6-examples
           path: modflow6-examples
@@ -421,8 +429,11 @@ jobs:
             bash
             powershell
 
-      - name: Setup Intel Fortran
-        uses: modflowpy/install-intelfortran-action@v1
+      - name: Setup ${{ inputs.compiler_toolchain }} ${{ inputs.compiler_version }}
+        uses: fortran-lang/setup-fortran@v1
+        with:
+          compiler: ${{ inputs.compiler_toolchain }}
+          version: ${{ inputs.compiler_version }}
       
       - name: Update version
         id: update_version
@@ -463,13 +474,9 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ github.token }}
         run: |
-          # install extra Python packages
           pip install -r modflow6-examples/etc/requirements.pip.txt
-  
-          # example models need executables to be on the path
           distname="${{ needs.build.outputs.distname }}_${{ matrix.ostag }}"
           echo "$distname/bin" >> $GITHUB_PATH
-
           # execute permissions may not have survived artifact upload/download
           chmod +x "$distname/bin/mf6"
           chmod +x "$distname/bin/mf5to6"
@@ -487,8 +494,8 @@ jobs:
   
       - name: Build example models
         if: inputs.full == true
-        working-directory: modflow6-examples/etc
-        run: python ci_build_files.py
+        working-directory: modflow6-examples/autotest
+        run: pytest -v -n auto test_scripts.py --init
 
       - name: Build distribution
         env:
@@ -523,10 +530,10 @@ jobs:
               $distname/utils \
               $distname/code.json \
               $distname/meson.build \
+              $distname/meson.options \
               -x '*.DS_Store' \
               -x '*libmf6.lib' \
               -x '*idmloader*' \
-              -x '*pymake*' \
               -x '*obj_temp*' \
               -x '*mod_temp*'
           else
@@ -538,7 +545,6 @@ jobs:
               -x '*.DS_Store' \
               -x '*libmf6.lib' \
               -x '*idmloader*' \
-              -x '*pymake*' \
               -x '*obj_temp*' \
               -x '*mod_temp*'
           fi
@@ -559,9 +565,9 @@ jobs:
               $distname/utils \
               $distname/code.json \
               $distname/meson.build \
+              $distname/meson.options \
               -xr!libmf6.lib \
               -xr!idmloader \
-              -xr!pymake \
               -xr!obj_temp \
               -xr!mod_temp
           else
@@ -572,26 +578,10 @@ jobs:
               $distname/code.json \
               -xr!libmf6.lib \
               -xr!idmloader \
-              -xr!pymake \
               -xr!obj_temp \
               -xr!mod_temp
           fi
 
-      # validate only after zipping distribution to avoid accidentally changing any files
-      - name: Validate distribution
-        run: |
-          cmd="pytest -v -s modflow6/distribution/check_dist.py --path ${{ needs.build.outputs.distname }}_${{ matrix.ostag }}"
-          if [[ "${{ inputs.approve }}" == "true" ]]; then
-            cmd="$cmd --approved"
-          fi
-          if [[ "${{ inputs.developmode }}" == "false" ]]; then
-             cmd="$cmd --releasemode"
-          fi
-          if [[ "${{ inputs.full }}" == "true" ]]; then
-            cmd="$cmd --full"
-          fi
-          eval "$cmd"
-
       - name: Upload distribution
         uses: actions/upload-artifact@v3
         with:
@@ -604,3 +594,28 @@ jobs:
         with:
           name: release_notes
           path: "${{ needs.build.outputs.distname }}_${{ matrix.ostag }}/doc/release.pdf"
+
+      - name: Check distribution
+        run: |
+          # unzip and validate the archive
+          distname="${{ needs.build.outputs.distname }}_${{ matrix.ostag }}"
+          distfile="$distname.zip"
+          checkdir="check"
+          mkdir $checkdir
+          if [[ "$RUNNER_OS" == "Windows" ]]; then
+            7z x $distfile -o$checkdir
+          else
+            unzip $distfile -d $checkdir
+          fi
+
+          cmd="pytest -v -s modflow6/distribution/check_dist.py --path $checkdir/$distname"
+          if [[ "${{ inputs.approve }}" == "true" ]]; then
+            cmd="$cmd --approved"
+          fi
+          if [[ "${{ inputs.developmode }}" == "false" ]]; then
+             cmd="$cmd --releasemode"
+          fi
+          if [[ "${{ inputs.full }}" == "true" ]]; then
+            cmd="$cmd --full"
+          fi
+          eval "$cmd"
\ No newline at end of file
diff --git a/.github/workflows/release_dispatch.yml b/.github/workflows/release_dispatch.yml
index 567bab3eae3..3037c98698e 100644
--- a/.github/workflows/release_dispatch.yml
+++ b/.github/workflows/release_dispatch.yml
@@ -24,6 +24,16 @@ on:
         description: 'Branch to release from.'
         required: true
         type: string
+      compiler_toolchain:
+        description: 'Compiler toolchain to use. For supported options see https://github.com/MODFLOW-USGS/modflow6/blob/develop/DEVELOPER.md#compiler-compatibility.'
+        required: false
+        type: string
+        default: 'intel-classic'
+      compiler_version:
+        description: 'Compiler version to use. For supported options see https://github.com/MODFLOW-USGS/modflow6/blob/develop/DEVELOPER.md#compiler-compatibility.'
+        required: false
+        type: string
+        default: '2021.7'
       commit_version:
         description: 'Commit version numbers back to the develop branch. Not considered if reset is false.'
         required: false
@@ -36,7 +46,7 @@ on:
         default: false
       run_tests:
         description: 'Run tests after building binaries.'
-        required: true
+        required: false
         type: boolean
         default: true
       version:
@@ -53,6 +63,8 @@ jobs:
         shell: bash -l {0}
     outputs:
       branch: ${{ steps.set_branch.outputs.branch }}
+      compiler_toolchain: ${{ steps.set_compiler.outputs.compiler_toolchain }}
+      compiler_version: ${{ steps.set_compiler.outputs.compiler_version }}
       version: ${{ steps.set_version.outputs.version }}
     steps:
       - name: Set branch
@@ -61,8 +73,8 @@ jobs:
           # if branch was provided explicitly via workflow_dispatch, use it
           if [[ ("${{ github.event_name }}" == "workflow_dispatch") && (-n "${{ inputs.branch }}") ]]; then
             branch="${{ inputs.branch }}"
-            # prevent releases from develop or master
-            if [[ ("$branch" == "develop") || ("$branch" == "master") ]]; then
+            # prevent releases from master
+            if [[ "$branch" == "master" ]]; then
               echo "error: releases may not be triggered from branch $branch"
               exit 1
             fi
@@ -77,6 +89,26 @@ jobs:
             exit 1
           fi
           echo "branch=$branch" >> $GITHUB_OUTPUT
+      - name: Set compiler
+        id: set_compiler
+        run: |
+          # if compiler toolchain was provided explicitly via workflow_dispatch, use it
+          if [[ ("${{ github.event_name }}" == "workflow_dispatch") && (-n "${{ inputs.compiler_toolchain }}") ]]; then
+            compiler_toolchain="${{ inputs.compiler_toolchain }}"
+            compiler_version="${{ inputs.compiler_version }}"
+            echo "using compiler toolchain $compiler_toolchain version $compiler_version from workflow_dispatch"
+          elif [[ ("${{ github.event_name }}" == "push") && ("${{ github.ref_name }}" != "master") ]]; then
+            # if release was triggered by pushing a release branch, use the default toolchain and version
+            compiler_toolchain="intel-classic"
+            compiler_version="2021.7"
+            echo "using default compiler toolchain $compiler_toolchain version $compiler_version"
+          else
+            # otherwise exit with an error
+            echo "error: this workflow should not have triggered for event ${{ github.event_name }} on branch ${{ github.ref_name }}"
+            exit 1
+          fi
+          echo "compiler_toolchain=$compiler_toolchain" >> $GITHUB_OUTPUT
+          echo "compiler_version=$compiler_version" >> $GITHUB_OUTPUT
       - name: Set version
         id: set_version
         run: |
@@ -103,6 +135,8 @@ jobs:
       # If the workflow is manually triggered, the maintainer must manually set approve=true to approve a release.
       # If triggered by pushing a release branch, the release is approved if the branch name doesn't contain "rc".
       approve: ${{ (github.event_name == 'workflow_dispatch' && inputs.approve == 'true') || (github.event_name != 'workflow_dispatch' && !contains(github.ref_name, 'rc')) }}
+      compiler_toolchain: ${{ needs.set_options.outputs.compiler_toolchain }}
+      compiler_version: ${{ needs.set_options.outputs.compiler_version }}
       branch: ${{ needs.set_options.outputs.branch }}
       developmode: false
       full: true
@@ -110,7 +144,7 @@ jobs:
       version: ${{ needs.set_options.outputs.version }}
   pr:
     name: Draft release PR
-    if: ${{ github.event_name == 'push' && github.ref_name != 'master' && (github.event_name == 'workflow_dispatch' && inputs.approve == 'true') || (github.event_name != 'workflow_dispatch' && !contains(github.ref_name, 'rc')) }}
+    if: ${{ github.ref_name != 'master' && ((github.event_name == 'workflow_dispatch' && inputs.approve == 'true') || (github.event_name != 'workflow_dispatch' && !contains(github.ref_name, 'rc'))) }}
     needs:
       - set_options
       - make_dist
@@ -123,7 +157,7 @@ jobs:
         shell: bash -l {0}
     steps:
       - name: Checkout modflow6
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: ${{ github.repository_owner }}/modflow6
           ref: ${{ github.ref }}
@@ -185,7 +219,7 @@ jobs:
         shell: bash -l {0}
     steps:
       - name: Checkout modflow6
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: ${{ github.repository_owner }}/modflow6
           path: modflow6
@@ -198,7 +232,7 @@ jobs:
           cache-environment: true
 
       - name: Download artifacts
-        uses: dawidd6/action-download-artifact@v2
+        uses: dawidd6/action-download-artifact@v3
 
       - name: Draft release
         working-directory: modflow6
@@ -229,7 +263,7 @@ jobs:
     steps:
 
       - name: Checkout modflow6
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: ${{ github.repository_owner }}/modflow6
           path: modflow6
diff --git a/.gitignore b/.gitignore
index 56b28c72ec8..959f560e70f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -133,3 +133,8 @@ unittests/
 
 **/__pycache__
 **/.benchmarks
+
+# compiler compatibility markdown tables
+.github/compat/*.md
+
+**.DS_Store
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
new file mode 100644
index 00000000000..c518b77c314
--- /dev/null
+++ b/.gitlab-ci.yml
@@ -0,0 +1,66 @@
+# Deploy MODFLOW 6 to HPC systems.
+#
+# Expects shared environment variables...
+#
+#  - GIT_REMOTE, name of the mf6 remote to pull from
+#  - GIT_BRANCH, name of the mf6 branch to pull from
+#  - MODULE_SCRIPT, module update script path (relative to mf6 proj root)
+#  - SSH_KNOWN_HOSTS, content of ~/.ssh/known_hosts
+#  - SSH_USERNAME, SSH username to login with
+#  - SSH_PRIVATE_KEY, SSH private key for user
+#
+# ...and environment-specific variables:
+#
+#  - DENALI_HOSTNAME, SSH hostname of cluster
+#  - DENALI_SLURM_ACCOUNT, slurm account for jobs
+#  - DENALI_SLURM_RESERVATION, slurm reservation for jobs
+#  - DENALI_MODULES_PATH, path to root of module system
+#  - DENALI_MF6_PREV_VERSION, version of modulefile to use as template
+#  - DENALI_MF6_PROJ_ROOT, path to modflow6 project root
+#  - DENALI_BUILD_SCRIPT, relpath of script to build mf6
+#
+# ...and likewise for HOVENWEEP_* or other systems
+
+image: ubuntu:20.04
+workflow:
+  rules:
+    - if: $CI_COMMIT_REF_NAME == $CI_DEFAULT_BRANCH && $CI_PIPELINE_SOURCE == 'push'
+before_script:
+  # install ssh agent
+  - 'which ssh-agent || ( apt-get update -y && apt-get install openssh-client git -y )'
+  # configure ssh agent
+  - eval $(ssh-agent -s)
+  # set private key permissions
+  - chmod 400 "$SSH_PRIVATE_KEY"
+  # add keys to the agent store
+  - ssh-add "$SSH_PRIVATE_KEY"
+  # configure known hosts
+  - mkdir -p ~/.ssh
+  - cp "$SSH_KNOWN_HOSTS" ~/.ssh/known_hosts
+  - chmod 644 ~/.ssh/known_hosts
+deploy_denali:
+  environment: denali
+  script: "$CI_PROJECT_DIR/.hpc/deploy.sh"
+  stage: deploy
+  variables:
+    SSH_USERNAME: $SSH_USERNAME
+    SSH_HOSTNAME: $DENALI_HOSTNAME
+    SLURM_ACCOUNT: $DENALI_SLURM_ACCOUNT
+    SLURM_RESERVATION: $DENALI_SLURM_RESERVATION
+    MODULES_PATH: $DENALI_MODULES_PATH
+    MF6_PROJ_ROOT: $DENALI_MF6_PROJ_ROOT
+    MF6_PREV_VERSION: $DENALI_MF6_PREV_VERSION
+    BUILD_SCRIPT: $DENALI_BUILD_SCRIPT
+deploy_hovenweep:
+  environment: hovenweep
+  script: "$CI_PROJECT_DIR/.hpc/deploy.sh"
+  stage: deploy
+  variables:
+    SSH_USERNAME: $SSH_USERNAME
+    SSH_HOSTNAME: $HOVENWEEP_HOSTNAME
+    SLURM_ACCOUNT: $HOVENWEEP_SLURM_ACCOUNT
+    SLURM_RESERVATION: $HOVENWEEP_SLURM_RESERVATION
+    MODULES_PATH: $HOVENWEEP_MODULES_PATH
+    MF6_PROJ_ROOT: $HOVENWEEP_MF6_PROJ_ROOT
+    MF6_PREV_VERSION: $HOVENWEEP_MF6_PREV_VERSION
+    BUILD_SCRIPT: $HOVENWEEP_BUILD_SCRIPT
\ No newline at end of file
diff --git a/.hpc/BUILD.md b/.hpc/BUILD.md
index dd8257e2b6d..9f9b0ac8374 100644
--- a/.hpc/BUILD.md
+++ b/.hpc/BUILD.md
@@ -1,20 +1,30 @@
+
 # Building MODFLOW 6 on HPC systems
 
-## SLURM job
+_On Denali_ 
 
 ```
 sbatch --reservation=dev cray-meson-build.slurm.batch
 ```
 
-## Interactive job
+_Hovenweep_
+
+```
+sbatch cray-hovenweep-meson-build.slurm.batch
+```
+
 
+## Create a module file for a new version of MODFLOW 6
+
+On _Denali_ make a copy of an existing module file using
+```
+rsync /home/software/denali/contrib/impd/modulefiles/modflow/6.5.0.dev0 /home/software/denali/contrib/impd/modulefiles/modflow/6.x.x
+```
+On _Hovenweep_ make a copy of an existing module file using
 ```
-module switch PrgEnv-${PE_ENV,,} PrgEnv-intel
-module load cray-petsc meson ninja
-export PKG_CONFIG_PATH=/opt/cray/pe/mpt/7.7.19/gni/mpich-intel/16.0/lib/pkgconfig:/opt/cray/pe/petsc/3.14.5.0/real/INTEL/19.1/x86_skylake/lib/pkgconfig:$PKG_CONFIG_PATH
+rsync /home/software/hovenweep/contrib/impd/modulefiles/modflow/6.5.0.dev0 /home/software/denali/contrib/impd/modulefiles/modflow/6.x.x
+```
+
+Edit `product_version` in the new module file from `6.5.0.dev0` to `6.x.x` on both systems.
 
-srun --reservation=dev --account=impd --pty bash
 
-meson setup builddir -Ddebug=false --prefix=$(pwd) --libdir=bin -Dcray=true -Ddebug=false --wipe
-meson install -C builddir
-```
\ No newline at end of file
diff --git a/.hpc/cray-hovenweep-meson-build.slurm.batch b/.hpc/cray-hovenweep-meson-build.slurm.batch
new file mode 100644
index 00000000000..a1020f54cf0
--- /dev/null
+++ b/.hpc/cray-hovenweep-meson-build.slurm.batch
@@ -0,0 +1,50 @@
+#!/bin/bash
+
+#SBATCH --job-name=hovenweep-build
+#SBATCH --nodes=1
+#SBATCH --ntasks=2
+#SBATCH --account=impd
+#SBATCH --time=00:10:00
+#SBATCH --output=slurm-%j.out
+#SBATCH --chdir=../
+
+set -euxo pipefail
+
+# load appropriate modules
+module switch PrgEnv-${PE_ENV,,} PrgEnv-intel
+module load petsc/3.15.5
+export PKG_CONFIG_PATH=$CRAY_MPICH_DIR/lib/pkgconfig:$PKG_CONFIG_PATH
+
+# list loaded modules
+module list
+
+# define the project root (expected to be cwd)
+MODFLOW6ROOT=$(pwd)
+
+# define the version
+VERSION=$(cat "$MODFLOW6ROOT/version.txt") 
+echo "MODFLOW 6 version: $VERSION"
+
+# define paths relative to the root directory
+BUILDDIR=$MODFLOW6ROOT/$PE_ENV-$VERSION
+BINDIR=$BUILDDIR/src
+TESTDIR=$MODFLOW6ROOT/.mf6minsim
+
+# define the installation location
+PREFIX=/home/software/hovenweep/contrib/impd/apps/modflow/$VERSION/$PE_ENV/2023.2.0
+
+# build MODFLOW 6
+CC=cc CXX=CC F77=ftn F90=ftn FC=ftn meson setup $BUILDDIR --prefix=$PREFIX --bindir=bin --libdir=lib -Dcray=true -Ddebug=false --wipe
+meson compile -C $BUILDDIR
+
+# install MODFLOW 6
+meson install -C $BUILDDIR
+
+# test MODFLOW 6 build
+cd $TESTDIR
+
+# serial run
+$BINDIR/mf6
+
+# parallel run
+srun $BINDIR/mf6 -p
\ No newline at end of file
diff --git a/.hpc/cray-meson-build.slurm.batch b/.hpc/cray-meson-build.slurm.batch
index c49de516198..1f62d43f6f3 100644
--- a/.hpc/cray-meson-build.slurm.batch
+++ b/.hpc/cray-meson-build.slurm.batch
@@ -1,11 +1,14 @@
 #!/bin/bash
 
-#SBATCH --job-name=meson-MODFLOW-build
+#SBATCH --job-name=denali-build
 #SBATCH --nodes=1
 #SBATCH --ntasks=2
 #SBATCH --account=impd
 #SBATCH --time=00:10:00
 #SBATCH --output=slurm-%j.out
+#SBATCH --chdir=../
+
+set -euxo pipefail
 
 # load appropriate modules
 module switch PrgEnv-${PE_ENV,,} PrgEnv-intel
@@ -15,17 +18,27 @@ export PKG_CONFIG_PATH=/opt/cray/pe/mpt/7.7.19/gni/mpich-intel/16.0/lib/pkgconfi
 # list loaded modules
 module list
 
-# move to root directory
-cd ..
+# define the project root (expected to be cwd)
+MODFLOW6ROOT=$(pwd)
+
+# define the version
+VERSION=$(cat "$MODFLOW6ROOT/version.txt") 
+echo "MODFLOW 6 version: $VERSION"
 
 # define paths relative to the root directory
-MODFLOW6ROOT=$(pwd)
-BINDIR=$MODFLOW6ROOT/bin
+BUILDDIR=$MODFLOW6ROOT/$PE_ENV-$VERSION
+BINDIR=$BUILDDIR/src
 TESTDIR=$MODFLOW6ROOT/.mf6minsim
 
+# define the installation location
+PREFIX=/home/software/denali/contrib/impd/apps/modflow/$VERSION/$PE_ENV/19.1.0.166
+
 # build MODFLOW 6
-CC=cc CXX=CC F77=ftn F90=ftn FC=ftn meson setup builddir --prefix=$(pwd) --libdir=bin -Dcray=true -Ddebug=false --wipe
-meson install -C builddir
+CC=cc CXX=CC F77=ftn F90=ftn FC=ftn meson setup $BUILDDIR --prefix=$PREFIX --bindir=bin --libdir=lib -Dcray=true -Ddebug=false
+meson compile -C $BUILDDIR
+
+# install MODFLOW 6
+meson install -C $BUILDDIR
 
 # test MODFLOW 6 build
 cd $TESTDIR
@@ -34,4 +47,4 @@ cd $TESTDIR
 $BINDIR/mf6
 
 # parallel run
-srun $BINDIR/mf6 -p
+srun $BINDIR/mf6 -p
\ No newline at end of file
diff --git a/.hpc/deploy.sh b/.hpc/deploy.sh
new file mode 100755
index 00000000000..b95b6c7f381
--- /dev/null
+++ b/.hpc/deploy.sh
@@ -0,0 +1,13 @@
+#!/bin/bash
+
+set -euxo pipefail
+
+# fetch and checkout latest
+ssh -l "$SSH_USERNAME" "$SSH_HOSTNAME" "cd $MF6_PROJ_ROOT && git fetch $GIT_REMOTE && git checkout $GIT_REMOTE/$GIT_BRANCH"
+echo "Updated repository $MF6_PROJ_ROOT"
+# submit a job to build mf6
+jobid=$(ssh -l "$SSH_USERNAME" "$SSH_HOSTNAME" "sbatch --account=$SLURM_ACCOUNT --reservation=$SLURM_RESERVATION --parsable -D $MF6_PROJ_ROOT $MF6_PROJ_ROOT/$BUILD_SCRIPT" | tail -n 1)
+echo "Submitted build job $jobid"
+# submit a job to update the mf6 module
+jobid=$(ssh -l "$SSH_USERNAME" "$SSH_HOSTNAME" "sbatch --export=ALL,MF6_PREV_VERSION=$MF6_PREV_VERSION,MF6_PROJ_ROOT=$MF6_PROJ_ROOT,MODULES_PATH=$MODULES_PATH --account=$SLURM_ACCOUNT --reservation=$SLURM_RESERVATION --parsable -D $MF6_PROJ_ROOT -d afterok:$jobid $MF6_PROJ_ROOT/$MODULE_SCRIPT" | tail -n 1)
+echo "Submitted module update job $jobid"
\ No newline at end of file
diff --git a/.hpc/update-module.slurm.batch b/.hpc/update-module.slurm.batch
new file mode 100644
index 00000000000..00135103525
--- /dev/null
+++ b/.hpc/update-module.slurm.batch
@@ -0,0 +1,31 @@
+#!/bin/bash
+
+#SBATCH --job-name=update-mf6-module
+#SBATCH --nodes=1
+#SBATCH --ntasks=1
+#SBATCH --account=impd
+#SBATCH --time=00:05:00
+#SBATCH --output=slurm-%j.out
+#SBATCH --chdir=../
+
+set -euxo pipefail
+
+# this script expects cwd to be mf6 project root, with env vars...
+# - MF6_PREV_VERSION, mf6 modulefile version to use as a template
+# - MODULES_PATH, the base path of the module system
+MF6_PROJ_ROOT=$(pwd)
+MF6_BINDIR="$MF6_PROJ_ROOT/bin"
+MF6_LOCAL_VERSION=$(cat "$MF6_PROJ_ROOT/version.txt")
+
+# ...and assumes the module system is laid out as follows
+MF6_MODULEFILE_PATH="$MODULES_PATH/modulefiles/modflow/$MF6_LOCAL_VERSION"
+MF6_MODULES_PATH="$MODULES_PATH/apps/modflow"
+MF6_MODULE_PATH="$MF6_MODULES_PATH/$MF6_LOCAL_VERSION"
+
+# create mf6 modulefile if needed (the build script
+# will have already created the module directory)
+if [ ! -f "$MF6_MODULEFILE_PATH" ]; then
+  rsync "$MODULES_PATH/modulefiles/modflow/$MF6_PREV_VERSION" "$MF6_MODULEFILE_PATH"
+  sed -i -e "s/$MF6_PREV_VERSION/$MF6_LOCAL_VERSION/g" "$MF6_MODULEFILE_PATH"
+  echo "Created module file: $MF6_MODULEFILE_PATH"
+fi
\ No newline at end of file
diff --git a/.readthedocs.yml b/.readthedocs.yml
index 086932137d8..808702f8077 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -5,6 +5,11 @@
 # Required
 version: 2
 
+build:
+  os: "ubuntu-22.04"
+  tools:
+    python: "3.11"
+
 # Build documentation in the docs/ directory with Sphinx
 sphinx:
   configuration: .doc/conf.py
@@ -18,6 +23,5 @@ formats: all
 
 # Optionally set the version of Python and requirements required to build your docs
 python:
-  version: 3.8
   install:
     - requirements: .build_rtd_docs/requirements.rtd.txt
diff --git a/.vscode/build_vscode.py b/.vscode/build_vscode.py
index 88d3e8b4c97..d222cc7c772 100644
--- a/.vscode/build_vscode.py
+++ b/.vscode/build_vscode.py
@@ -24,7 +24,7 @@
 if args.buildtype == "release":
     setup_flag = ["-Doptimization=2"]
 elif args.buildtype == "debug":
-    setup_flag = ["-Doptimization=0"]
+    setup_flag = ["-Ddebug=true", "-Doptimization=0"]
 
 if not os.path.isdir(builddir):
     command = [
diff --git a/.vscode/tasks.json b/.vscode/tasks.json
index 490baff6416..76f6cb2fe2d 100644
--- a/.vscode/tasks.json
+++ b/.vscode/tasks.json
@@ -26,7 +26,10 @@
                 "release",
                 "build",
             ],
-            "group": "build",
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            },
             "presentation": {
                 "clear": true
             }
@@ -53,7 +56,10 @@
                 "release",
                 "rebuild",
             ],
-            "group": "build",
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            },
             "presentation": {
                 "clear": true
             }
@@ -81,7 +87,10 @@
                 "release",
                 "build",
             ],
-            "group": "build",
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            },
             "presentation": {
                 "clear": true
             }
@@ -108,7 +117,10 @@
                 "release",
                 "rebuild",
             ],
-            "group": "build",
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            },
             "presentation": {
                 "clear": true
             }
@@ -136,7 +148,10 @@
                 "debug",
                 "build",
             ],
-            "group": "build",
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            },
             "presentation": {
                 "clear": true
             }
@@ -163,7 +178,10 @@
                 "debug",
                 "rebuild",
             ],
-            "group": "build",
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            },
             "presentation": {
                 "clear": true
             }
@@ -191,7 +209,10 @@
                 "debug",
                 "build",
             ],
-            "group": "build",
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            },
             "presentation": {
                 "clear": true
             }
@@ -218,7 +239,10 @@
                 "debug",
                 "rebuild",
             ],
-            "group": "build",
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            },
             "presentation": {
                 "clear": true
             }
diff --git a/CITATION.cff b/CITATION.cff
index b378cfa4c99..1595372ce9e 100644
--- a/CITATION.cff
+++ b/CITATION.cff
@@ -2,8 +2,8 @@ cff-version: 1.2.0
 message: If you use this software, please cite the software itself.
 type: software
 title: MODFLOW 6 Modular Hydrologic Model
-version: 6.4.2
-date-released: '2023-06-28'
+version: 6.4.3
+date-released: '2024-02-07'
 doi: 10.5066/F76Q1VQV
 abstract: MODFLOW 6 is an object-oriented program and framework developed to provide
   a platform for supporting multiple models and multiple types of models within the
@@ -58,6 +58,11 @@ authors:
   alias: w-bonelli
   affiliation: U.S. Geological Survey
   orcid: https://orcid.org/0000-0002-2665-5078
+- family-names: Boyce
+  given-names: Scott E.
+  alias: ScottBoyce
+  affiliation: U.S. Geological Survey
+  orcid: https://orcid.org/0000-0003-0626-9492
 - family-names: Banta
   given-names: Edward R.
   affiliation: U.S. Geological Survey
diff --git a/CODE_OF_CONDUCT.md b/CODE_OF_CONDUCT.md
index 62f6ede8b94..d89a4670001 100644
--- a/CODE_OF_CONDUCT.md
+++ b/CODE_OF_CONDUCT.md
@@ -1,7 +1,7 @@
 Code of Conduct
 ===============
 
-All contributions to- and interactions surrounding- this project will abide by
+All contributions to &mdash; and interactions surrounding &mdash; this project will abide by
 the [USGS Code of Scientific Conduct][1].
 
 
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 96e163a9268..e751d48539d 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -141,7 +141,7 @@ To ensure consistency throughout the source code, keep these rules in mind as yo
 ## <a name="format"></a> Format Rules
 
 Fortran souce code format rules are met by running the
-[fprettify formatter](https://github.com/pseewald/fprettify) while specifying the [MODFLOW 6 fprettify configuration](https://github.com/MODFLOW-USGS/modflow6/blob/develop/distribution/.fprettify.yaml). `fprettify` is included in the Conda `environment.yml` and can be run on the command line or integrated into a [VSCode](https://github.com/MODFLOW-USGS/modflow6/blob/develop/.vscode/README.md) or Visual Studio environment.
+[fprettify formatter](https://github.com/pseewald/fprettify) while specifying the [MODFLOW 6 fprettify configuration](.fprettify.yaml). `fprettify` is included in the Conda `environment.yml` and can be run on the command line or integrated into a [VSCode](.vscode/README.md) or Visual Studio environment.
 
 The configuration file reflects the current minimum standard for Fortran source
 formatting.  The main goal, however, is consistent and readable Fortran source code and as such pay particular attention to consistency within and across files. As the formatting tool may at times shift code in unexpected ways, check for formatting consistency after running.
@@ -234,9 +234,3 @@ The body should include the motivation for the change and contrast this with pre
 The footer should contain any information about **Breaking Changes** and is also the place to reference GitHub issues that this commit **Closes**.
 
 **Breaking Changes** should start with the word `BREAKING CHANGE:` with a space or two newlines. The rest of the commit message is then used for this.
-
-
-[coc]: https://github.com/MODFLOW-USGS/modflow6/blob/develop/CODE_OF_CONDUCT.md
-[dev-doc]: https://github.com/MODFLOW-USGS/modflow6/blob/develop/DEVELOPER.md
-[github]: https://github.com/MODFLOW-USGS/modflow6
-[stackoverflow]: http://stackoverflow.com/questions/tagged/modflow6
diff --git a/DEVELOPER.md b/DEVELOPER.md
index cc53837d8f0..ce6d7a47783 100644
--- a/DEVELOPER.md
+++ b/DEVELOPER.md
@@ -17,6 +17,9 @@ To build and test a parallel version of the program, first read the instructions
       - [Windows](#windows)
     - [Intel Fortran](#intel-fortran)
       - [Windows](#windows-1)
+    - [Compiler compatibility](#compiler-compatibility)
+      - [Compile](#compile)
+      - [Test](#test)
   - [Python](#python)
     - [Dependencies](#dependencies)
       - [`meson`](#meson)
@@ -32,17 +35,32 @@ To build and test a parallel version of the program, first read the instructions
 - [Building](#building)
 - [Testing](#testing)
   - [Configuring a test environment](#configuring-a-test-environment)
-    - [Building development binaries](#building-development-binaries)
-    - [Rebuilding and installing release binaries](#rebuilding-and-installing-release-binaries)
-    - [Updating `flopy` plugins](#updating-flopy-plugins)
-    - [External model repositories](#external-model-repositories)
-    - [Installing external repos](#installing-external-repos)
-      - [Test models](#test-models)
-      - [Example models](#example-models)
-  - [Running Tests](#running-tests)
-    - [Selecting tests with markers](#selecting-tests-with-markers)
-    - [External model tests](#external-model-tests)
-    - [Writing tests](#writing-tests)
+    - [Configuring unit tests](#configuring-unit-tests)
+    - [Configuring integration tests](#configuring-integration-tests)
+      - [Rebuilding release binaries](#rebuilding-release-binaries)
+      - [Updating FloPy packages](#updating-flopy-packages)
+      - [Installing external models](#installing-external-models)
+  - [Running tests](#running-tests)
+    - [Running unit tests](#running-unit-tests)
+    - [Running integration tests](#running-integration-tests)
+      - [Selecting tests with markers](#selecting-tests-with-markers)
+  - [Writing tests](#writing-tests)
+    - [Writing unit tests](#writing-unit-tests)
+    - [Writing integration tests](#writing-integration-tests)
+- [Generating makefiles](#generating-makefiles)
+  - [Updating extra and excluded files](#updating-extra-and-excluded-files)
+  - [Testing makefiles](#testing-makefiles)
+  - [Installing `make` on Windows](#installing-make-on-windows)
+    - [Using Conda from Git Bash](#using-conda-from-git-bash)
+- [Branching model](#branching-model)
+  - [Overview](#overview)
+  - [Managing long-lived branches](#managing-long-lived-branches)
+    - [Backup](#backup)
+    - [Squash](#squash)
+    - [Rebase](#rebase)
+    - [Cleanup](#cleanup)
+- [Deprecation policy](#deprecation-policy)
+  - [Finding deprecations](#finding-deprecations)
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
 
@@ -79,8 +97,16 @@ GNU Fortran can be installed on all three major platforms.
 
 ##### macOS
 
-- [Homebrew](https://brew.sh/): `brew install gcc`
-- [MacPorts](https://www.macports.org/): `sudo port install gcc10`
+- [Homebrew](https://brew.sh/): `brew install gcc@13`
+- [MacPorts](https://www.macports.org/): `sudo port install gcc13`
+
+**Note:** Xcode 15 includes a new linker implementation which breaks GNU Fortran compatibility. A workaround is to set `LDFLAGS` to use the classic linker, for instance:
+
+```shell
+export LDFLAGS="$LDFLAGS -Wl,-ld_classic"
+```
+
+See [this ticket](https://github.com/mesonbuild/meson/issues/12282) on the Meson repository for more information.
 
 ##### Windows
 
@@ -96,10 +122,12 @@ GNU Fortran can be installed on all three major platforms.
 
 #### Intel Fortran
 
-Intel Fortran can also be used to compile MODFLOW 6 and associated utilities. The `ifort` compiler is available in the [Intel oneAPI HPC Toolkit](https://software.intel.com/content/www/us/en/develop/tools/oneapi/hpc-toolkit/download.html). An installer is bundled with the download.
+Intel Fortran can also be used to compile MODFLOW 6 and associated utilities. The `ifort` and `ifx` compilers are available in the [Intel oneAPI HPC Toolkit](https://software.intel.com/content/www/us/en/develop/tools/oneapi/hpc-toolkit/download.html).
 
 A number of environment variables must be set before using Intel Fortran. General information can be found [here](https://www.intel.com/content/www/us/en/develop/documentation/oneapi-programming-guide/top/oneapi-development-environment-setup.html), with specific instructions to configure a shell session for `ifort` [here](https://www.intel.com/content/www/us/en/develop/documentation/fortran-compiler-oneapi-dev-guide-and-reference/top/compiler-setup/use-the-command-line/specifying-the-location-of-compiler-components.html).
 
+While the current development version of MODFLOW 6 is broadly compatible with `ifort`, `ifx` compatibility is still limited on Ubuntu and Windows, and `ifx` is not supported on macOS.
+
 ##### Windows
 
 On Windows, [Visual Studio](https://visualstudio.microsoft.com) and a number of libraries must be installed for `ifort` to work. The required libraries can be installed by ticking the "Desktop Development with C++" checkbox in the Visual Studio Installer's Workloads tab. 
@@ -110,6 +138,36 @@ On Windows, [Visual Studio](https://visualstudio.microsoft.com) and a number of
 cmd.exe "/K" '"C:\Program Files (x86)\Intel\oneAPI\setvars-vcvarsall.bat" && "C:\Program Files (x86)\Intel\oneAPI\compiler\latest\env\vars.bat" && powershell'
 ```
 
+#### Compiler compatibility
+
+The following tables are automatically generated by [a CI workflow](.github/workflows/compilers.yml).
+
+##### Compile
+
+<!-- compile compat starts -->
+| runner       | gcc 10   | gcc 11   | gcc 12   | gcc 13   | gcc 7   | gcc 8   | gcc 9   | intel-classic 2021.1   | intel-classic 2021.10   | intel-classic 2021.2   | intel-classic 2021.3   | intel-classic 2021.4   | intel-classic 2021.5   | intel-classic 2021.6   | intel-classic 2021.7   | intel-classic 2021.8   | intel-classic 2021.9   |   intel 2021.1 |   intel 2021.2 |   intel 2021.4 |   intel 2022.0 |   intel 2022.1 | intel 2022.2.1   | intel 2022.2   |   intel 2023.0 |   intel 2023.1 | intel 2023.2   |
+|:-------------|:----------------|:----------------|:----------------|:----------------|:---------------|:---------------|:---------------|:------------------------------|:-------------------------------|:------------------------------|:------------------------------|:------------------------------|:------------------------------|:------------------------------|:------------------------------|:------------------------------|:------------------------------|----------------------:|----------------------:|----------------------:|----------------------:|----------------------:|:------------------------|:----------------------|----------------------:|----------------------:|:----------------------|
+| macos-11     | &check;         | &check;         | &check;         | &check;         | &check;        | &check;        | &check;        | &check;                       | &check;                        | &check;                       | &check;                       | &check;                       | &check;                       | &check;                       | &check;                       | &check;                       | &check;                       |                    |                    |                    |                    |                    |                      |                    |                    |                    |                    |
+| macos-12     | &check;         | &check;         | &check;         | &check;         | &check;        | &check;        | &check;        | &check;                       | &check;                        | &check;                       | &check;                       | &check;                       | &check;                       | &check;                       | &check;                       | &check;                       | &check;                       |                    |                    |                    |                    |                    |                      |                    |                    |                    |                    |
+| ubuntu-20.04 | &check;         | &check;         |              |              | &check;        | &check;        | &check;        | &check;                       | &check;                        | &check;                       |                            | &check;                       | &check;                       | &check;                       | &check;                       | &check;                       | &check;                       |                    |                    |                    |                    |                    | &check;                 | &check;               |                    |                    | &check;               |
+| ubuntu-22.04 | &check;         | &check;         | &check;         | &check;         |             |             | &check;        | &check;                       | &check;                        | &check;                       |                            | &check;                       | &check;                       | &check;                       | &check;                       | &check;                       | &check;                       |                    |                    |                    |                    |                    | &check;                 | &check;               |                    |                    | &check;               |
+| windows-2019 | &check;         | &check;         | &check;         | &check;         |             |             | &check;        |                            | &check;                        |                            |                            |                            |                            | &check;                       | &check;                       | &check;                       | &check;                       |                    |                    |                    |                    |                    |                      | &check;               |                    |                    | &check;               |
+| windows-2022 | &check;         | &check;         | &check;         | &check;         |             |             | &check;        |                            | &check;                        |                            |                            |                            |                            | &check;                       | &check;                       | &check;                       | &check;                       |                    |                    |                    |                    |                    |                      | &check;               |                    |                    | &check;               |
+<!-- compile compat ends -->
+
+##### Test
+
+<!-- test compat starts -->
+| runner       | gcc 10   | gcc 11   | gcc 12   | gcc 13   | gcc 7   | gcc 8   | gcc 9   | intel-classic 2021.1   |   intel-classic 2021.10 | intel-classic 2021.2   | intel-classic 2021.3   | intel-classic 2021.4   | intel-classic 2021.5   | intel-classic 2021.6   | intel-classic 2021.7   |   intel-classic 2021.8 |   intel-classic 2021.9 |   intel 2021.1 |   intel 2021.2 |   intel 2021.4 |   intel 2022.0 |   intel 2022.1 |   intel 2022.2.1 |   intel 2022.2 |   intel 2023.0 |   intel 2023.1 |   intel 2023.2 |
+|:-------------|:----------------|:----------------|:----------------|:----------------|:---------------|:---------------|:---------------|:------------------------------|-------------------------------:|:------------------------------|:------------------------------|:------------------------------|:------------------------------|:------------------------------|:------------------------------|------------------------------:|------------------------------:|----------------------:|----------------------:|----------------------:|----------------------:|----------------------:|------------------------:|----------------------:|----------------------:|----------------------:|----------------------:|
+| macos-11     | &check;         | &check;         | &check;         | &check;         | &check;        | &check;        | &check;        | &check;                       |                             | &check;                       | &check;                       | &check;                       | &check;                       | &check;                       | &check;                       |                            |                            |                    |                    |                    |                    |                    |                      |                    |                    |                    |                    |
+| macos-12     | &check;         | &check;         | &check;         | &check;         |             |             |             | &check;                       |                             | &check;                       | &check;                       | &check;                       | &check;                       | &check;                       | &check;                       |                            |                            |                    |                    |                    |                    |                    |                      |                    |                    |                    |                    |
+| ubuntu-20.04 | &check;         | &check;         |              |              | &check;        | &check;        | &check;        | &check;                       |                             | &check;                       |                            | &check;                       | &check;                       | &check;                       | &check;                       |                            |                            |                    |                    |                    |                    |                    |                      |                    |                    |                    |                    |
+| ubuntu-22.04 | &check;         | &check;         | &check;         | &check;         |             |             | &check;        | &check;                       |                             | &check;                       |                            | &check;                       | &check;                       | &check;                       | &check;                       |                            |                            |                    |                    |                    |                    |                    |                      |                    |                    |                    |                    |
+| windows-2019 |              |              |              | &check;         |             |             |             |                            |                             |                            |                            |                            |                            | &check;                       | &check;                       |                            |                            |                    |                    |                    |                    |                    |                      |                    |                    |                    |                    |
+| windows-2022 | &check;         | &check;         | &check;         | &check;         |             |             | &check;        |                            |                             |                            |                            |                            |                            | &check;                       | &check;                       |                            |                            |                    |                    |                    |                    |                    |                      |                    |                    |                    |                    |
+<!-- test compat ends -->
+
 ### Python
 
 Python 3.8+ is required to run MODFLOW 6 tests. A Conda distribution (e.g. [miniconda](https://docs.conda.io/en/latest/miniconda.html) or [Anaconda](https://www.anaconda.com/products/individual) is recommended. Python dependencies are specified in `environment.yml`. To create an environment, run from the project root:
@@ -141,7 +199,7 @@ These are each described briefly below. The Conda `environment.yml` contains a n
 
 ##### `fprettify`
 
-[`fprettify`](https://github.com/pseewald/fprettify) can be used to format Fortran source code and in combination with the [MODFLOW 6 fprettify configuration](https://github.com/MODFLOW-USGS/modflow6/blob/develop/distribution/.fprettify.yaml) establishes a contribution standard for properly formatted MODFLOW 6 Fortran source. This tool can be installed with `pip` or `conda` and used from the command line or integrated with a [VSCode](https://github.com/MODFLOW-USGS/modflow6/blob/develop/.vscode/README.md) or Visual Studio development environment. The `fprettify` package is included in the Conda environment in `environment.yml`. See [contribution guidelines](https://github.com/MODFLOW-USGS/modflow6/blob/develop/CONTRIBUTING.md) for additional information.
+[`fprettify`](https://github.com/pseewald/fprettify) can be used to format Fortran source code and in combination with the [MODFLOW 6 fprettify configuration](.fprettify.yaml) establishes a contribution standard for properly formatted MODFLOW 6 Fortran source. This tool can be installed with `pip` or `conda` and used from the command line or integrated with a [VSCode](.vscode/README.md) or Visual Studio development environment. The `fprettify` package is included in the Conda environment in `environment.yml`. See [contribution guidelines](CONTRIBUTING.md) for additional information.
 
 ##### `mfpymake`
 
@@ -151,7 +209,7 @@ The `mfpymake` package can build MODFLOW 6 and related programs and artifacts (e
 
 [`flopy`](https://github.com/modflowpy/flopy) is used throughout MODFLOW 6 tests to create, run and post-process models.
 
-Like MODFLOW 6, `flopy` is modular &mdash; for each MODFLOW 6 package there is generally a corresponding `flopy` plugin. Plugins are generated dynamically from DFN files stored in this repository under `doc/mf6io/mf6ivar/dfn`.
+Like MODFLOW 6, `flopy` is modular &mdash; for each MODFLOW 6 package there is generally a corresponding `flopy` package. Packages are generated dynamically from DFN files stored in this repository under `doc/mf6io/mf6ivar/dfn`.
 
 ##### `modflow-devtools`
 
@@ -198,11 +256,12 @@ git remote add upstream https://github.com/MODFLOW-USGS/modflow6.git
 
 Meson is the recommended build tool for MODFLOW 6. [Meson](https://mesonbuild.com/Getting-meson.html) must be installed and on your [PATH](https://en.wikipedia.org/wiki/PATH_(variable)). Creating and activating the Conda environment `environment.yml` should be sufficient for this.
 
-Meson build configuration files are provided for MODFLOW 6 as well as `zbud6` and `mf5to6` utility programs:
+Meson build configuration files are provided for MODFLOW 6, for the ZONEBUDGET and MODFLOW 2005 to 6 converter utility programs, and for Fortran unit tests (see [Testing](#testing) section below).
 
 - `meson.build`
 - `utils/zonebudget/meson.build`
 - `utils/mf5to6/meson.build`
+- `autotest/meson.build`
 
 To build MODFLOW 6, first configure the build directory. By default Meson uses compiler flags for a release build. To create a debug build, add `-Doptimization=0` to the following `setup` command.
 
@@ -232,45 +291,58 @@ The binaries can then be found in the `bin` folder. `meson install` also trigger
 
 ## Testing
 
-MODFLOW 6 tests are driven with [`pytest`](https://docs.pytest.org/en/7.1.x/), with the help of plugins like `pytest-xdist` and `pytest-cases`. Testing dependencies are included in the Conda environment `environment.yml`.
+MODFLOW 6 unit tests are written in Fortran with [`test-drive`](https://github.com/fortran-lang/test-drive).
+
+MODFLOW 6 integration tests are written in Python with [`pytest`](https://docs.pytest.org/en/7.1.x/). Integration testing dependencies are included in the Conda environment `environment.yml`.
 
 **Note:** the entire test suite should pass before a pull request is submitted. Tests run in GitHub Actions CI and a PR can only be merged with passing tests. See [`CONTRIBUTING.md`](CONTRIBUTING.md) for more information.
 
 ### Configuring a test environment
 
-A few tasks must be completed before running tests:
+Before running tests, there are a few steps to complete. Most importantly, the local development version of MODFLOW 6 must be built, e.g. with Meson as described above.
 
-- build local MODFLOW 6 development version
-- rebuild the last MODFLOW 6 release
-- install additional executables
-- update FloPy packages and plugins
-- clone MODFLOW 6 test model and example repositories
+The `autotest/build_exes.py` script is provided as a shortcut to rebuild local binaries. It can be invoked as a standard Python script or with Pytest. By default, binaries are placed in the `bin` directory relative to the project root, as in the Meson commands described above. To change the location of the binaries, use the `--path` option.
 
-Tests expect binaries to live in the `bin` directory relative to the project root, as configured above in the `meson` commands. Binaries are organized as follows:
+#### Configuring unit tests
 
-- local development binaries in the top-level `bin` folder
-- binaries rebuilt in development mode from the latest release in `bin/rebuilt`
-- related programs installed from the [executables distribution](https://github.com/MODFLOW-USGS/executables/releases) live in `bin/downloaded`
+Unit tests are [driven with Meson](https://mesonbuild.com/Unit-tests.html). A small number of Meson-native tests are defined in the top-level `meson.build` file to check that MODFLOW 6 has installed successfully. These require no additional configuration.
 
-Tests must be run from the `autotest` folder.
+Additional Fortran unit tests are defined with [`test-drive`](https://github.com/fortran-lang/test-drive) in the `autotest/` folder, with test files named `Test*.f90`. If Meson fails to find the `test-drive` library via `pkg-config`, these will be skipped.
 
-#### Building development binaries
+To install `test-drive`:
 
-Before running tests, the local development version of MODFLOW 6 must be built with `meson` as described above. The `autotest/build_exes.py` script is provided as a shortcut to easily rebuild local binaries. The script can be run from the project root with:
+1. Clone the `test-drive` repository
+2. Setup/build with Meson, e.g. in a Unix shell from the `test-drive` project root:
 
 ```shell
-python autotest/build_exes.py
+meson setup builddir --prefix=$PWD --libdir=lib
+meson install -C builddir
 ```
 
-Alternatively, it can be run from the `autotest` directory with `pytest`:
+3. Add `<test-drive project root>/lib/pkgconfig` to the `PKG_CONFIG_PATH` environment variable.
+4. To confirm that `test-drive` is detected by `pkg-config`, run `pkg-config --libs test-drive`.
 
-```shell
-pytest build_exes.py
-```
+Meson should now detect the `test-drive` library when building MODFLOW 6.
+
+**Note:** the `test-drive` source code is not yet compatible with recent versions of Intel Fortran, building with `gfortran` is recommended.
 
-By default, binaries will be placed in the `bin` directory relative to the project root, as in the `meson` commands described above. To change the location of the binaries, use the `--path` option.
+See the [Running unit tests](#running-unit-tests) section for instructions on running unit tests.
 
-#### Rebuilding and installing release binaries
+#### Configuring integration tests
+
+A few more tasks must be completed before integration testing:
+
+- install MODFLOW-related executables
+- ensure FloPy packages are up to date
+- install MODFLOW 6 example/test models
+
+As mentioned above, binaries live in the `bin` subdirectory of the project root. This directory is organized as follows:
+
+- local development binaries in the top-level `bin`
+- binaries rebuilt in development mode from the latest MODFLOW 6 release in `bin/rebuilt/`
+- related programs installed from the [executables distribution](https://github.com/MODFLOW-USGS/executables/releases) in `bin/downloaded/`
+
+##### Rebuilding release binaries
 
 Tests require the latest official MODFLOW 6 release to be compiled in develop mode with the same Fortran compiler as the development version. A number of binaries distributed from the [executables repo](https://github.com/MODFLOW-USGS/executables) must also be installed. The script `autotest/get_exes.py` does both of these things. It can be run from the project root with:
 
@@ -284,70 +356,56 @@ Alternatively, with `pytest` from the `autotest` directory:
 pytest get_exes.py
 ```
 
-By default, binaries will be placed in the `bin` directory relative to the project root, as in the `meson` commands described above. Nested `bin/downloaded` and `bin/rebuilt` directories are created to contain the rebuilt last release and the downloaded executables, respectively. To change the location of the binaries, use the `--path` option.
+As above, binaries are placed in the `bin` subdirectory of the project root, with nested `bin/downloaded` and `bin/rebuilt` subdirectories containing the rebuilt latest release and downloaded binaries, respectively.
 
-#### Updating `flopy` plugins
+##### Updating FloPy packages
 
-Plugins should be regenerated from DFN files before running tests for the first time or after definition files change. This can be done with the `autotest/update_flopy.py` script, which wipes and regenerates plugin classes for the `flopy` installed in the Python environment.
+FloPy packages should be regenerated from DFN files before running tests for the first time or after definition files change. This can be done with the `autotest/update_flopy.py` script, which wipes and regenerates package classes for the FloPy installed in the Python environment.
 
-**Note:** if you've installed a local version of `flopy` from source, running this script can overwrite files in your repository.
+**Note:** if you've installed an editable local version of FloPy from source, running this script can overwrite files in your repository.
 
-There is a single optional argument, the path to the folder containing definition files. By default DFN files are assumed to live in `doc/mf6io/mf6ivar/dfn`, making the following identical:
+There is a single optional argument, the path to the folder containing definition files. By default DFN files are assumed to live in `doc/mf6io/mf6ivar/dfn`, making the following functionally identical:
 
 ```shell
 python autotest/update_flopy.py
 python autotest/update_flopy.py doc/mf6io/mf6ivar/dfn
 ```
 
-#### External model repositories
+##### Installing external models
 
-Some autotests load example models from external repositories:
+Some autotests load models from external repositories:
 
 - [`MODFLOW-USGS/modflow6-testmodels`](https://github.com/MODFLOW-USGS/modflow6-testmodels)
 - [`MODFLOW-USGS/modflow6-largetestmodels`](https://github.com/MODFLOW-USGS/modflow6-largetestmodels)
 - [`MODFLOW-USGS/modflow6-examples`](https://github.com/MODFLOW-USGS/modflow6-examples)
 
-#### Installing external repos
-
-By default, the tests expect these repositories side-by-side with (i.e. in the same parent directory as) the `modflow6` repository. If the repos are somewhere else, you can set the `REPOS_PATH` environment variable to point to their parent directory. If external model repositories are not found, tests requiring them will be skipped.
-
-**Note:** a convenient way to persist environment variables needed for tests is to store them in a `.env` file in the `autotest` folder. Each variable should be defined on a separate line, with format `KEY=VALUE`. The `pytest-dotenv` plugin will then automatically load any variables found in this file into the test process' environment.
-
-##### Test models
+See the [MODFLOW devtools documentation](https://modflow-devtools.readthedocs.io/en/latest/md/install.html#installing-external-model-repositories) for instructions to install external model repositories.
 
-The test model repos can simply be cloned &mdash; ideally, into the parent directory of the `modflow6` repository, so that repositories live side-by-side:
+### Running tests
 
-```shell
-git clone MODFLOW-USGS/modflow6-testmodels
-git clone MODFLOW-USGS/modflow6-largetestmodels
-```
+MODFLOW 6 has two kinds of tests: Fortran unit tests, driven with Meson, and Python integration tests, driven with Pytest.
 
-##### Example models
+#### Running unit tests
 
-First clone the example models repo:
+Unit tests must be run from the project root. To run unit tests in verbose mode:
 
 ```shell
-git clone MODFLOW-USGS/modflow6-examples
+meson test -C builddir --no-rebuild --verbose
 ```
 
-The example models require some setup after cloning. Some extra Python dependencies are required to build the examples: 
-
-```shell
-cd modflow6-examples/etc
-pip install -r requirements.pip.txt
-```
+Without the `--no-rebuild` options, Meson will rebuild the project before running tests.
 
-Then, still from the `etc` folder, run:
+Unit tests can be selected by module name (as listed in `autotest/tester.f90`). For instance, to test the `ArrayHandlersModule`:
 
 ```shell
-python ci_build_files.py
+meson test -C builddir --no-rebuild --verbose ArrayHandlers
 ```
 
-This will build the examples for subsequent use by the tests.
+To run a test module in the `gdb` debugger, just add the `--gdb` flag to the test command.
 
-### Running Tests
+#### Running integration tests
 
-Tests are driven by `pytest` and must be run from the `autotest` folder. To run tests in a particular file, showing verbose output, use:
+Integration tests must be run from the `autotest/` folder. To run tests in a particular file, showing verbose output, use:
 
 ```shell
 pytest -v <file>
@@ -359,7 +417,7 @@ Tests can be run in parallel with the `-n` option, which accepts an integer argu
 pytest -v -n auto
 ```
 
-#### Selecting tests with markers
+##### Selecting tests with markers
 
 Markers can be used to select subsets of tests. Markers provided in `pytest.ini` include:
 
@@ -382,8 +440,6 @@ pytest -v -n auto -S
 
 [Smoke testing](https://modflow-devtools.readthedocs.io/en/latest/md/markers.html#smoke-testing) is a form of integration testing which aims to test a decent fraction of the codebase quickly enough to run often during development.
 
-#### External model tests
-
 Tests using models from external repositories can be selected with the `repo` marker:
 
 ```shell
@@ -396,27 +452,64 @@ The `large` marker is a subset of the `repo` marker. To test models excluded fro
 pytest -v -n auto -m "large"
 ```
 
-Test scripts for external model repositories can also be run independently:
+Tests load external models from fixtures provided by `modflow-devtools`. External model tests can be selected by model or simulation name, or by packages used. See the [`modflow-devtools` documentation](https://modflow-devtools.readthedocs.io/en/latest/md/fixtures.html#filtering) for usage examples. Note that filtering options only apply to tests using external models, and will not filter tests defining models in code &mdash; for that, the `pytest` built-in `-k` option may be used.
 
-```shell
-# MODFLOW 6 test models
-pytest -v -n auto test_z01_testmodels_mf6.py
+### Writing tests
+
+#### Writing unit tests
+
+To add a new unit test:
+
+- Add a file containing a test module, e.g. `TestArithmetic.f90`, to the `autotest/` folder.
+
+```fortran
+module TestArithmetic
+  use testdrive, only : error_type, unittest_type, new_unittest, check, test_failed
+  implicit none
+  private
+  public :: collect_arithmetic
+contains
+  
+  subroutine collect_arithmetic(testsuite)
+    type(unittest_type), allocatable, intent(out) :: testsuite(:)
+    testsuite = [new_unittest("add", test_add)]
+  end subroutine collect_arithmetic
+
+  subroutine test_add(error)
+    type(error_type), allocatable, intent(out) :: error
+    call check(error, 1 + 1 == 2, "Math works")
+    if (allocated(error)) then
+      call test_failed(error, "Math is broken")
+      return
+    end if
+  end subroutine test_add
+end module TestArithmetic
+```
+
+- Add the module name to the list of `tests` in `autotest/meson.build`, omitting the leading "Test".
 
-# MODFLOW 5 to 6 conversion test models
-pytest -v -n auto test_z02_testmodels_mf5to6.py
+```fortran
+tests = [
+  'Arithmetic',
+]
+```
 
-# models from modflow6-examples repo
-pytest -v -n auto test_z03_examples.py
+- Add a `use` statement for the test module in `autotest/tester.f90`, and add it to the array of `testsuites`.
 
-# models from modflow6-largetestmodels repo
-pytest -v -n auto test_z03_largetestmodels.py
+```fortran
+use TestArithmetic, only: collect_arithmetic
+...
+testsuites = [ &
+  new_testsuite("Arithmetic", collect_arithmetic), &
+  new_testsuite("something_else", collect_something_else) &
+]
 ```
 
-Tests load external models from fixtures provided by `modflow-devtools`. External model tests can be selected by model or simulation name, or by packages used. See the [`modflow-devtools` documentation](https://modflow-devtools.readthedocs.io/en/latest/md/fixtures.html#filtering) for usage examples. Note that filtering options only apply to tests using external models, and will not filter tests defining models in code &mdash; for that, the `pytest` built-in `-k` option may be used.
+- Rebuild with Meson from the project root, e.g. `meson install -C builddir`. The test should now be picked up when `meson test...` is next invoked.
 
-#### Writing tests
+#### Writing integration tests
 
-Tests should ideally follow a few conventions for easier maintenance:
+Integration tests should ideally follow a few conventions for easier maintenance:
 
 - Use temporary directory fixtures. Tests which write to disk should use `pytest`'s built-in `tmp_path` fixtures or one of the [keepable temporary directory fixtures from `modflow-devtools`](https://modflow-devtools.readthedocs.io/en/latest/md/fixtures.html#keepable-temporary-directories). This prevents tests from polluting one another's state.
 
@@ -426,3 +519,199 @@ Tests should ideally follow a few conventions for easier maintenance:
   - `@pytest.mark.regression` if the test compares results from different versions
 
 **Note:** If all three external model repositories are not installed as described above, some tests will be skipped. The full test suite includes >750 cases. All must pass before changes can be merged into this repository.
+
+##### Test framework
+
+A framework has been developed to streamline common testing patterns. The [`TestFramework`](autotest/framework.py) class, defined in `autotest/framework.py`, is used by most test scripts to configure, run and evaluate one or more MF6 simulations, optionally in comparison with another simulation or model.
+
+Generally, the recommended pattern for a test script is:
+
+```python
+import ...
+
+cases = ["a", "b", ...]
+variable = [1., 0., ...]
+expected = [-1., -1.1, ...]
+
+def build_models(idx, test):
+  v = variable[idx]
+  ...
+
+def check_output(idx, test):
+  e = expected[idx]
+  ...
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+    )
+    test.run()
+```
+
+The framework has two hooks:
+
+- `build`: construct one or more MF6 simulations and/or non-MF6 models with FloPy
+- `check`: evaluate simulation/model output
+
+A test script conventionally contains one or more test cases, fed to the test function as `idx, name` pairs. `idx` can be used to index parameter values or expected results for a specific test case. The test case `name` is useful for model/subdirectory naming, etc.
+
+The framework will not run an unknown program. The path to any program under test (or used for a comparison) must be registered in the `targets` dictionary. Keys are strings. See `autotest/conftest.py` for the contents of `targets` &mdash; naming follows the [executables distribution](https://github.com/MODFLOW-USGS/executables).
+
+The `.run()` function
+
+1. builds simulations/models
+2. runs simulations/models
+3. compares simulation/model outputs
+4. checks outputs against expectations
+
+A `compare` parameter may be provided on initialization, which enables comparison of outputs against another program or the latest official release of MF6. The following values are supported:
+
+- `None`: disables comparison &mdash; the test simply runs/evaluates any registered simulations/models without comparing results
+- `auto`: attempt to detect the comparison type from contents of test workspace, otherwise skipping comparison
+- `mf6_regression`: compare results against the latest official release rebuilt in develop mode
+- `mf6`, `mf2005`, `mfnwt`, or `mflgr`: compare with results from the selected program &mdash; a corresponding model must be provided in `build_models()`
+
+After running the reference and comparison models, the framework will try to find correspondingly named output files to compare &mdash; comparison logic may need adjustment when writing tests for new packages or models.
+
+## Generating makefiles
+
+Run `build_makefiles.py` in the `distribution/` directory after adding, removing, or renaming source files. This script uses [Pymake](https://github.com/modflowpy/pymake) to regenerate makefiles. For instance:
+
+```shell
+python build_makefiles.py
+```
+
+### Updating extra and excluded files
+
+If the utilities located in the `utils` directory (e.g., `mf5to6` and `zbud6`) are affected by changes to the modflow6 `src/` directory (such as new or refactored source files), then the new module source file should also be added to the utility's `utils/<util>/pymake/extrafiles.txt` file. This file informs Pymake of source files living outside the main source directory, so they can be included in generated makefiles.
+
+Module dependencies for features still under development should be added to `excludefiles.txt`. Source files listed in this file will be excluded from makefiles generated by Pymake. Makefiles should only include the source files needed to the build officially released/supported features.
+
+### Testing makefiles
+
+Makefile generation and usage can be tested from the `distribution` directory by running the `build_makefiles.py` script with Pytest:
+
+```shell
+pytest -v build_makefiles.py
+```
+
+**Note**: `make` is required to test compiling MODFLOW 6 with makefiles. If `make` is not discovered on the system path, compile tests will be skipped.
+
+Makefiles may also be tested manually by changing to the appropriate `make` subdirectory (of the project root for MODFLOW 6, or inside the corresponding `utils` subdirectory for the zonebudget or converter utilities) and invoking `make` (`make clean` may first be necessary to remove previously created object files).
+
+### Installing `make` on Windows
+
+On Windows, it is recommended to generate and test makefiles from a Unix-like shell rather than PowerShell or Command Prompt. Make can be installed via [Conda](https://anaconda.org/conda-forge/make) or [Chocolatey](https://community.chocolatey.org/packages/make). Alternatively, it is included with [mingw](https://sourceforge.net/projects/mingw/), which is also available from [Chocolatey](https://community.chocolatey.org/packages/mingw).
+
+#### Using Conda from Git Bash
+
+To use Conda from Git Bash on Windows, first run the `conda.sh` script located in your Conda installation's `/etc/profile.d` subdirectory. For instance, with Anaconda3:
+
+```shell
+. /c/Anaconda3/etc/profile.d/conda.sh
+```
+
+Or Miniconda3:
+
+```shell
+. /c/ProgramData/miniconda3/etc/profile.d/conda.sh
+```
+
+After this, `conda` commands should be available.
+
+This command may be added to a `.bashrc` or `.bash_profile` file in your home directory to permanently configure Git Bash for Conda.
+
+## Branching model
+
+This section documents MODFLOW 6 branching strategy and other VCS-related procedures.
+
+### Overview
+
+This project follows the [git flow](https://nvie.com/posts/a-successful-git-branching-model/): development occurs on the `develop` branch, while `master` is reserved for the state of the latest release. Development PRs are typically squashed to `develop` to avoid merge commits. At release time, release branches are merged to `master`, and then `master` is merged back into `develop`.
+
+### Managing long-lived branches
+
+When a feature branch takes a long time to develop, it is easy to become out of sync with the develop branch.  Depending on the situation, it may be advisable to periodically squash the commits on the feature branch and rebase the change set with develop.  The following approach for updating a long-lived feature branch has proven robust.
+
+In the example below, the feature branch is assumed to be called `feat-xyz`.
+
+#### Backup
+
+Begin by creating a backup copy of the feature branch in case anything goes terribly wrong.
+
+```
+git checkout feat-xyz
+git checkout -b feat-xyz-backup
+git checkout feat-xyz
+```
+
+#### Squash
+
+Next, consider squashing commits on the feature branch.  If there are many commits, it is beneficial to squash them before trying to rebase with develop.  There is a nice article on [squashing commits into one using git](https://www.internalpointers.com/post/squash-commits-into-one-git), which has been very useful for consolidating commits on a long-lived modflow6 feature branch.
+
+A quick and dirty way to squash without interactive rebase (as an alternative to the approach described in the article mentioned in the preceding paragraph) is a soft reset followed by an ammended commit. First making a backup of the feature branch is strongly recommended before using this approach, as accidentally typing `--hard` instead of `--soft` will wipe out all your work.
+
+```
+git reset --soft <first new commit on the feature branch>
+git commit --amend -m "consolidated commit message"
+```
+
+Once the commits on the feature branch have been consolidated, a force push to origin is recommended.  This is not strictly required, but it can serve as an intermediate backup/checkpoint so the squashed branch state can be retrieved if rebasing fails.  The following command will push `feat-xyz` to origin.
+
+```
+git push origin feat-xyz --force
+```
+
+The `--force` flag's short form is `-f`.
+
+#### Rebase
+
+Now that the commits on `feat-xyz` have been consolidated, it is time to rebase with develop.  If there are multiple commits in `feat-xyz` that make changes, undo them, rename files, and/or move things around in subsequent commits, then there may be multiple sets of merge conflicts that will need to be resolved as the rebase works its way through the commit change sets.  This is why it is beneficial to squash the feature commits before rebasing with develop.
+
+To rebase with develop, make sure the feature branch is checked out and then type:
+
+```
+git rebase develop
+```
+
+If anything goes wrong during a rebase, there is the `rebase --abort` command to unwind it.
+
+If there are merge conflicts, they will need to be resolved before going forward.  Once any conflicts are resolved, it may be worthwhile to rebuild the MODFLOW 6 program and run the smoke tests to ensure nothing is broken.  
+
+At this point, you will want to force push the updated feature branch to origin using the same force push command as before.
+
+```
+git push origin feat-xyz --force
+```
+
+#### Cleanup
+
+Lastly, if you are satisfied with the results and confident the procedure went well, then you can delete the backup that you created at the start.
+
+```
+git branch -d feat-xyz-backup
+```
+
+This process can be repeated periodically to stay in sync with the develop branch and keep a clean commit history.
+
+## Deprecation policy
+
+To deprecate a MODFLOW 6 input/output option in a DFN file:
+
+- Add a new `deprecated x.y.z` attribute to the appropriate variable in the package DFN file, where `x.y.z` is the version the deprecation is introduced. Mention the deprecation prominently in the release notes.
+- If support for the deprecated option is removed (typically after at least 2 minor or major releases or 1 year), add a new `removed x.y.z` attribute to the variable in the DFN file, where `x.y.z` is the version in which support for the option was removed. The line containing `deprecated x.y.z` should not be deleted. Mention the removal prominently in the release notes.
+- Deprecated/removed attributes are not removed from DFN files but remain in perpetuity. The `doc/mf6io/mf6ivar/deprecations.py` script generates a markdown deprecation table which is converted to LaTeX by `doc/ReleaseNotes/mk_deprecations.py` for inclusion in the MODFLOW 6 release notes. Deprecations and removals should still be mentioned separately in the release notes, however.
+
+### Finding deprecations
+
+To search for deprecations and removals in DFN files on a system with `git` and standard Unix commands available:
+
+```shell
+git grep 'deprecated' -- '*.dfn' | awk '/^*.dfn:deprecated/'
+```
diff --git a/PARALLEL.md b/PARALLEL.md
index 8229ae1cbbb..3d1e8f11ebc 100644
--- a/PARALLEL.md
+++ b/PARALLEL.md
@@ -5,7 +5,7 @@ This document describes how to set up your build environment for developing and
 ---
 **DISCLAIMER**
 
-*Expectations on platform compatibility* 
+*Expectations on platform compatibility*
 
 The serial version of the MODFLOW 6 program has had no external dependencies and is traditionally available for a variety of platforms (Windows, GNU/linux, macOS) and compatible with the mainstream Fortran compilers (gfortran, ifort). The parallel version comes with dependencies on third party components, most notably the MPI and PETSc libraries. While the goal is a continued support of the above mentioned configurations, this has become more challenging and can generally not be guaranteed. To assist developers as well as end users who are planning to compile the code themselves, a list of successfully tested build configurations will be included in this document.
 
@@ -19,7 +19,7 @@ The design philosophy has been to maintain MODFLOW as a single codebase and have
 
 ## Prerequisites
 
-The parallel version of MODFLOW 6 requires the the Message Passing Interface (MPI) and the Portable, Extensible Toolkit for Scientific Computation (PETSc - pronounced PET-see (/ˈpɛt-siː/)) libraries. 
+The parallel version of MODFLOW 6 requires the Message Passing Interface (MPI) and the Portable, Extensible Toolkit for Scientific Computation (PETSc - pronounced PET-see (/ˈpɛt-siː/)) libraries.
 
 ### MPI
 
@@ -36,7 +36,7 @@ In addition to compiling, the MPI toolset is also required to run a parallel sim
 
 ### PETSc
 
-The PETSc library is a suite of data structures and routines for the scalable (parallel) solution of scientific applications modeled by partial differential equations: 
+The PETSc library is a suite of data structures and routines for the scalable (parallel) solution of scientific applications modeled by partial differential equations:
 
 https://petsc.org/release/
 
@@ -44,38 +44,41 @@ The PETSc library (version 3.16 or higher) is used by MODFLOW for its parallel l
 
 ## Compiling MPI and PETSC from source
 
-The PETSc website gives details on a large number of configurations, depending on the target platform/OS, and many different ways to configure/make/install the library: https://petsc.org/release/install/. Building on Windows is notoriously challenging and discouraged by the PETSc development team. On Linux, however, PETSc can be installed (configure/make/install) by executing the following command 
+The PETSc website gives details on a large number of configurations, depending on the target platform/OS, and many different ways to configure/make/install the library: https://petsc.org/release/install/. Building on Windows is notoriously challenging and discouraged by the PETSc development team. On Linux, however, PETSc can be installed (configure/make/install) by executing the following command
+
 ```
 $ ./configure --download-openmpi --download-fblaslapack
 $ make all
 ```
-in a terminal open in the root directory of your PETSc download
-
 
+in a terminal open in the root directory of your PETSc download
 
 ## Using a package manager to install MPI and PETSc
 
 Use of a package manager can simplify the process of building the parallel version of MODFLOW 6.
 
 ### MacOS
+
 [OpenMPI](https://formulae.brew.sh/formula/open-mpi) and [PETSc](https://formulae.brew.sh/formula/petsc) are available on Homebrew for Intel and Apple Silicon (M1). Both of these depend on [gcc 13.1.0](https://formulae.brew.sh/formula/gcc). [pkg-config](https://formulae.brew.sh/formula/pkg-config) should also be installed from Homebrew, if not already installed, so that Meson will be able to resolve the installation location of MPI and PETSc.
 
 ### Ubuntu
-OpenMPI and PETSc are available for a variety of Ubuntu versions using the Advanced Packaging Tool (apt). 
+
+OpenMPI and PETSc are available for a variety of Ubuntu versions using the Advanced Packaging Tool (apt).
 
 ### Windows
 
-???
+Under evaluation.
 
 ## Using pkg-config to check your PETSc installation
 
-Eventually, the MODFLOW build process has to resolve the installation location of all external dependencies. The pkg-config tool (https://en.wikipedia.org/wiki/Pkg-config) can be used to take care of that. 
+Eventually, the MODFLOW build process has to resolve the installation location of all external dependencies. The pkg-config tool (https://en.wikipedia.org/wiki/Pkg-config) can be used to take care of that.
 
 ```
 pkg-config --libs petsc
 ```
 
 If PETSc was build from source, you can check the contents of the folder
+
 ```
 $PETSC_DIR/$PETSC_ARCH/lib/pkgconfig/
 ```
@@ -84,7 +87,6 @@ and confirm that there are one or more `*.pc` files in there. A similar `pkgconf
 
 To connect everything, both of these folder paths have to be added to the `PKG_CONFIG_PATH` variable so that the `pkg-config` executable can resolve the installed libraries.
 
-
 ## Building the parallel version of MODFLOW 6
 
 The primary build system for MODFLOW is Meson (https://mesonbuild.com/). The `meson.build` script takes an additional argument to activate a parallel build of the software. E.g for building and installing a parallel release version:
@@ -95,11 +97,12 @@ meson setup builddir -Ddebug=false -Dparallel=true \
 meson install -C builddir
 meson test --verbose --no-rebuild -C builddir
 ```
+
 Note that changing the option flags in the `meson setup` command requires the flag `--reconfigure` to reconfigure the build directory. If the `PKG_CONFIG_PATH` was set as described above, the linking to PETSc and MPI is done automatically.
 
-It's always a good idea to check your `mf6pro` executable to confirm that it is successfully linked against the external dependencies. You can use the command line tools `ldd` (Linux), `otool` (macOS), or `Dependencies.exe` (Windows, https://github.com/lucasg/Dependencies) to do that. In the list of dependencies, you should be able to identify `libpetsc` and `libmpi` for parallel builds.
+It's always a good idea to check your parallel MODFLOW executable to confirm that it is successfully linked against the external dependencies. You can use the command line tools `ldd` (Linux), `otool` (macOS), or `Dependencies.exe` (Windows, https://github.com/lucasg/Dependencies) to do that. In the list of dependencies, you should be able to identify `libpetsc` and `libmpi` for parallel builds.
 
-The other build systems in the MODFLOW project (MS Visual Studio, `pymake`, `Makefile`) continue to be supported for *serial* builds only. `pymake` uses the `excludefiles.txt` to ignore those files that can only be build when MPI and PETSc are present on the system. In MS Visual Studio these same files are included in the solution but not in the build process. 
+The other build systems in the MODFLOW project (MS Visual Studio, `pymake`, `Makefile`) continue to be supported for *serial* builds only. `pymake` uses the `excludefiles.txt` to ignore those files that can only be build when MPI and PETSc are present on the system. In MS Visual Studio these same files are included in the solution but not in the build process.
 
 ---
 
@@ -111,8 +114,7 @@ Parallel MODFLOW was designed to have all third party functionality (MPI and PET
 
 ---
 
-
-## Testing the parallel of MODFLOW 6 
+## Testing the parallel of MODFLOW 6
 
 Parallel MODFLOW can be tested using the same test framework as the serial program, with just a few modifications. To run a test inside the `autotest` folder in parallel mode, make sure to add a marker `@pytest.mark.parallel` so that the test is only executed in the Continuous Integration when running a configuration with a parallel build of MODFLOW.
 
@@ -121,6 +123,7 @@ The `TestSimulation` object that is being run from the framework should be confi
 ```
 $ pytest -s --parallel test_par_gwf01.py
 ```
+
 Running without the `--parallel` flag will simply skip the test.
 
 ## Debugging
@@ -130,11 +133,13 @@ The most straightforward way to debug a parallel simulation is to start a run an
 ```
 -wait_dbg
 ```
+
 telling MODFLOW to pause immediately after startup. This will give you time to attach one or multiple debuggers to the processes. Then start the parallel program, for example on two cores:
 
 ```
 mpiexec -np 2 mf6 -p
 ```
+
 In the process explorer you should now see 2 processes called `mf6` or `mf6.exe`. On the prompt where the command was executed, MODFLOW waits for input:
 
 ```
@@ -165,7 +170,8 @@ In VSCode parallel debugging is easiest done by duplicating the development envi
     ]
   }
 ```
-After building parallel MODFLOW, press `Ctrl+Shift+p` to execute *Workspaces: Duplicate As Workspace in New Window*. This will open a second VSCode window, identical to the first. Starting the debug process and selecting *"Attach to ..."* pop ups a process selection window with the processes started from the `mpiexec` command described above. Select both, each from their own instance of the VSCode program. Now you can put breakpoints in the code, "Hit enter to continue" on the command prompt, and step through the parallel processes side-by-side.
+
+After building parallel MODFLOW, press `Ctrl+Shift+p` to execute *Workspaces: Duplicate As Workspace in New Window*. This will open a second VSCode window, identical to the first. Starting the debug process and selecting *"Attach to ..."* opens a process selection window with the processes started from the `mpiexec` command described above. Select both, each from their own instance of the VSCode program. Now you can put breakpoints in the code, "Hit enter to continue" on the command prompt, and step through the parallel processes side-by-side.
 
 ---
 **TIP**
@@ -174,19 +180,23 @@ Make sure that you work with gdb versions >= 10. We have found that earlier vers
 
 ---
 
-
 ## Compatibility
 
 Parallel MODFLOW has been built successfully with the following configurations:
 
-| Operating System      |   Toolchain |      MPI      |  PETSc | Package Manager |
-|-----------------------|-------------|---------------|--------|-----------------|
-| MS Windows            | ?           | ?             | ?      | NA              |
-| WSL2 (Ubuntu 20.04.5) | gcc 9.4.0   | OpenMPI 4.0.3 | 3.18.2 | NA              |
-| Ubuntu 22.04          | gcc 9.5.0   | OpenMPI 4.1.4 | 3.18.5 | NA              |
-| Ubuntu 23.04          | gcc 13      | OpenMPI 4.1.4 | 3.18.1 | apt             |
-| macOS 12.6.3          | gcc 9.5.0   | OpenMPI 4.1.4 | 3.18.5 | NA              |
-| macOS 12.6.6          | gcc 13.1.0  | OpenMPI 4.1.5 | 3.19.1 | Homebrew        |
+| Operating System                    | Toolchain                 | MPI               | PETSc               | Package Manager |
+|-------------------------------------|---------------------------|-------------------|---------------------|-----------------|
+| MS Windows                          | ?                         | ?                 | ?                   | NA              |
+| WSL2 (Ubuntu 20.04.5)               | gcc 9.4.0                 | OpenMPI 4.0.3     | 3.18.2              | NA              |
+| macOS 12.6.3                        | gcc 9.5.0                 | OpenMPI 4.1.4     | 3.18.5              | NA              |
+| macOS 12.6.6                        | gcc 13.1.0                | OpenMPI 4.1.5     | 3.19.1              | Homebrew        |
+| Ubuntu 22.04                        | gcc 9.5.0                 | OpenMPI 4.1.4     | 3.18.5              | NA              |
+| Ubuntu 22.04 ARM64                  | gcc 11.4.0                | OpenMPI 4.1.5     | 3.19.3              | apt             |
+| Ubuntu 22.04 ARM64                  | gcc 9.5.0                 | MPICH 3.4.1       | 3.15.5              | NA              |
+| Ubuntu 22.04 ARM64                  | gcc 12.3.0                | MPICH 4.1.1       | 3.19.6              | NA              |
+| Ubuntu 22.04 ARM64                  | gcc 12.3.0                | MPICH 4.1.1       | 3.20.0              | NA              |
+| SUSE Linux Enterprise Server 15 SP2 | intel 19.1.0.166 20191121 | CRAY-MPICH 7.7.19 | CRAY-PETSC 3.14.5.0 | NA              |
+| Red Hat Enterprise Linux 8.7        | intel 2021.10.0 20230609  | CRAY-MPICH 8.1.26 | 3.15.5              | NA              |
 
 The most up-to-date configurations are available in the GitHub CI script: `.github/workflows/ci.yml` under the task `parallel_test`. These are being tested upon every change to the `develop` branch of MODFLOW.
 
@@ -194,4 +204,46 @@ To improve support, we kindly ask you to share your experience with building and
 
 ## Known issues
 
-tbd
\ No newline at end of file
+### Building PETSc on Ubuntu 22.04 with MPICH and GNU compilers
+
+Versions of PETSc that use MPICH 3.4 (v3.14, v3.15, v3.16)) must be built with gcc-9 or earlier. Versions of PETSc that use MPICH 4.1 (v3.17 or newer) can be built with newer versions of the gcc compiler (gcc-11, gcc-12, etc.).
+
+Meson does not correctly load the Fortran compiler flags from the `mpich.pc` package configuration file in the `$PETSC_DIR/$PETSC_ARCH/lib/pkgconfig` directory. To overcome this issue, make a copy of `mpich.pc` and name it `mpichfort.pc`. Then determine the appropriate Fortran flags using
+
+```
+$PETSC_DIR/$PETSC_ARCH/bin/mpifort -show
+```
+
+which will return something like
+
+```
+$ linux-real-gcc12.3.0-3.20.0/bin/mpifort -show
+gfortran -fPIC -ffree-line-length-none -ffree-line-length-0 -Wno-lto-type-mismatch -O2 -fallow-argument-mismatch -I/media/psf/Development/petsc/linux-real-gcc12.3.0-3.20.0/include -I/media/psf/Development/petsc/linux-real-gcc12.3.0-3.20.0/include -L/media/psf/Development/petsc/linux-real-gcc12.3.0-3.20.0/lib -lmpifort -Wl,-rpath -Wl,/media/psf/Development/petsc/linux-real-gcc12.3.0-3.20.0/lib -Wl,--enable-new-dtags -lmpi
+```
+
+Copy the returned Fortran flags and replace the `Libs:` and `Cflags:` attributes in  the `mpichfort.pc` file. Also modify the `Name:` attribute to `mpichfort`. The modified `mpichfort.pc` file should look something like
+
+```
+# this gives access to the mpich header files
+prefix=/media/psf/Development/petsc/linux-real-gcc9.5.0-3.20.0
+exec_prefix=${prefix}
+libdir=/media/psf/Development/petsc/linux-real-gcc9.5.0-3.20.0/lib
+includedir=${prefix}/include
+
+Name: mpichfort
+Description: High Performance and portable MPI
+Version: 4.1.2
+URL: http://www.mcs.anl.gov/research/projects/mpich
+Requires:
+Libs: -fPIC -ffree-line-length-none -ffree-line-length-0 -Wno-lto-type-mismatch -O2 -fallow-argument-mismatch -I/media/psf/Development/petsc/linux-real-gcc12.3.0-3.20.0/include -I/media/psf/Development/petsc/linux-real-gcc12.3.0-3.20.0/include -L/media/psf/Development/petsc/linux-real-gcc12.3.0-3.20.0/lib -lmpifort -Wl,-rpath -Wl,/media/psf/Development/petsc/linux-real-gcc12.3.0-3.20.0/lib -Wl,--enable-new-dtags -lmpi 
+Cflags:  -fPIC -ffree-line-length-none -ffree-line-length-0 -Wno-lto-type-mismatch -O2 -fallow-argument-mismatch -I/media/psf/Development/petsc/linux-real-gcc12.3.0-3.20.0/include -I/media/psf/Development/petsc/linux-real-gcc12.3.0-3.20.0/include -L/media/psf/Development/petsc/linux-real-gcc12.3.0-3.20.0/lib -lmpifort -Wl,-rpath -Wl,/media/psf/Development/petsc/linux-real-gcc12.3.0-3.20.0/lib -Wl,--enable-new-dtags -lmpi
+
+# pkg-config does not understand Cxxflags, etc. So we allow users to
+# query them using the --variable option
+
+cxxflags= -Wno-lto-type-mismatch -Wno-psabi -O2 -std=gnu++17 -fPIC -I${includedir}
+fflags=-fPIC -ffree-line-length-none -ffree-line-length-0 -Wno-lto-type-mismatch -O2 -I${includedir}
+fcflags=-fPIC -ffree-line-length-none -ffree-line-length-0 -Wno-lto-type-mismatch -O2 -I${includedir}
+```
+
+The `/media/psf/Development/petsc/linux-real-gcc12.3.0-3.20.0/include` and `/media/psf/Development/petsc/linux-real-gcc12.3.0-3.20.0/lib` entries in the `Libs:` and `Cflags:` attributes can be replaced with `${includedir}` and `${libdir}`, respectively, to simplify `mpichfort.pc`.
\ No newline at end of file
diff --git a/README.md b/README.md
index 306731b232e..5e561c379b6 100644
--- a/README.md
+++ b/README.md
@@ -3,7 +3,7 @@
 
 This is the development repository for the USGS MODFLOW 6 Hydrologic Model. The  official USGS distribution is available at [USGS Release Page](https://water.usgs.gov/ogw/modflow/MODFLOW.html).
 
-### Version 6.4.2
+### Version 6.4.3
 
 [![GitHub release](https://img.shields.io/github/release/MODFLOW-USGS/modflow6.svg)](https://github.com/MODFLOW-USGS/modflow6/releases/latest)
 [![MODFLOW 6 continuous integration](https://github.com/MODFLOW-USGS/modflow6/actions/workflows/ci.yml/badge.svg)](https://github.com/MODFLOW-USGS/modflow6/actions/workflows/ci.yml)
@@ -94,6 +94,8 @@ The GWT model for MODFLOW 6 simulates three-dimensional transport of a single so
 
 [Hughes, J.D., Leake, S.A., Galloway, D.L., and White, J.T., 2022, Documentation for the Skeletal Storage, Compaction, and Subsidence (CSUB) Package of MODFLOW 6: U.S. Geological Survey Techniques and Methods, book 6, chap. A62, 57 p., https://doi.org/10.3133/tm6A62](https://doi.org/10.3133/tm6A62)
 
+[Langevin, C.D., Hughes, J.D., Provost, A.M., Russcher, M.J. and Panday, S., 2023, MODFLOW as a Configurable Multi-Model Hydrologic Simulator: Groundwater, https://doi.org/10.1111/gwat.13351](https://doi.org/10.1111/gwat.13351)
+
 #### ***Software/Code***
 
 The following is the general citation for the MODFLOW 6 software.
diff --git a/autotest/TestArrayHandlers.f90 b/autotest/TestArrayHandlers.f90
new file mode 100644
index 00000000000..321beb7b16c
--- /dev/null
+++ b/autotest/TestArrayHandlers.f90
@@ -0,0 +1,353 @@
+module TestArrayHandlers
+  use KindModule, only: I4B, DP, LGP
+  use testdrive, only: error_type, unittest_type, new_unittest, check, &
+                       test_failed, to_string
+  use ArrayHandlersModule, only: ExpandArray, ExpandArray2D, ExtendPtrArray, &
+                                 remove_character
+  use ConstantsModule, only: LINELENGTH
+  implicit none
+  private
+  public :: collect_arrayhandlers
+
+contains
+
+  subroutine collect_arrayhandlers(testsuite)
+    type(unittest_type), allocatable, intent(out) :: testsuite(:)
+    testsuite = [ &
+                new_unittest("ExpandArray_int", &
+                             test_ExpandArray_int), &
+                new_unittest("ExpandArray_dbl", &
+                             test_ExpandArray_dbl), &
+                new_unittest("ExpandArray_lgp", &
+                             test_ExpandArray_lgp), &
+                new_unittest("ExpandArray2D_int", &
+                             test_ExpandArray2D_int), &
+                new_unittest("ExpandArray2D_dbl", &
+                             test_ExpandArray2D_dbl), &
+                ! new_unittest("ExtendPtrArray_int", &
+                !              test_ExtendPtrArray_int), &
+                ! new_unittest("ExtendPtrArray_dbl", &
+                !              test_ExtendPtrArray_dbl), &
+                new_unittest("remove_character", &
+                             test_remove_character) &
+                ]
+  end subroutine collect_arrayhandlers
+
+  !> @brief Test 1D int array expansion
+  subroutine test_ExpandArray_int(error)
+    type(error_type), allocatable, intent(out) :: error
+    integer(I4B), allocatable :: a(:)
+    integer(I4B) :: i, lb, n1, n2
+
+    n1 = 2 ! starting size
+    n2 = 5 ! expanded size
+    do lb = -1, 1 ! test default lower bound (1) as well as 0 and -1
+      ! allocate/populate array
+      allocate (a(lb:(lb + n1 - 1)))
+      a(lb) = lb
+      a(lb + 1) = lb + 1
+
+      ! resize array and check new size and bounds
+      call ExpandArray(a, n2 - n1)
+      call check(error, size(a, 1) == n2, &
+                 "unexpected size: "//to_string(size(a, 1)))
+      call check(error, lbound(a, 1) == lb, &
+                 "unexpected lower bound: "//to_string(lbound(a, 1)))
+      call check(error, ubound(a, 1) == lb + n2 - 1, &
+                 "unexpected upper bound: "//to_string(ubound(a, 1)))
+      if (allocated(error)) return
+
+      ! set new array elements and check new/old contents
+      do i = lb + n1 - 1, lb + n2 - 1
+        a(i) = i
+      end do
+      do i = lb, lb + n2 - 1
+        call check(error, a(i) == i, &
+                   "unexpected value "//to_string(a(i)) &
+                   //" at i="//to_string(i))
+        if (allocated(error)) return
+      end do
+      deallocate (a)
+    end do
+  end subroutine test_ExpandArray_int
+
+  !> @brief Test 1D dbl array expansion
+  subroutine test_ExpandArray_dbl(error)
+    type(error_type), allocatable, intent(out) :: error
+    real(DP), allocatable :: a(:)
+    integer(I4B) :: i, lb, n1, n2
+
+    n1 = 2 ! starting size
+    n2 = 5 ! expanded size
+    do lb = -1, 1 ! test with default lower bound (1) as well as 0 and -1
+      ! allocate/populate array
+      allocate (a(lb:(lb + n1 - 1)))
+      a(lb) = real(lb)
+      a(lb + 1) = real(lb + 1)
+
+      ! resize array and check new size and bounds
+      call ExpandArray(a, n2 - n1)
+      call check(error, size(a, 1) == n2, &
+                 "unexpected size: "//to_string(size(a, 1)))
+      call check(error, lbound(a, 1) == lb, &
+                 "unexpected lower bound: "//to_string(lbound(a, 1)))
+      call check(error, ubound(a, 1) == lb + n2 - 1, &
+                 "unexpected upper bound: "//to_string(ubound(a, 1)))
+      if (allocated(error)) return
+
+      ! set new array elements and check new/old contents
+      do i = lb + n1 - 1, lb + n2 - 1
+        a(i) = real(i)
+      end do
+      do i = lb, lb + n2 - 1
+        call check(error, a(i) == real(i), &
+                   "unexpected value "//to_string(a(i)) &
+                   //" at i="//to_string(i))
+        if (allocated(error)) return
+      end do
+      deallocate (a)
+    end do
+  end subroutine test_ExpandArray_dbl
+
+  !> @brief Test 1D logical array expansion
+  subroutine test_ExpandArray_lgp(error)
+    type(error_type), allocatable, intent(out) :: error
+    logical(LGP), allocatable :: a(:)
+    integer(I4B) :: i, lb, n1, n2
+
+    n1 = 2 ! starting size
+    n2 = 5 ! expanded size
+    do lb = -1, 1 ! test with default lower bound (1) as well as 0 and -1
+      ! allocate/populate array (alternate T/F starting with false)
+      allocate (a(lb:(lb + n1 - 1)))
+      a(lb) = mod(lb, 2) == 0
+      a(lb + 1) = mod(lb + 1, 2) == 0
+
+      ! resize array and check new size and bounds
+      call ExpandArray(a, n2 - n1)
+      call check(error, size(a, 1) == n2, &
+                 "unexpected size: "//to_string(size(a, 1)))
+      call check(error, lbound(a, 1) == lb, &
+                 "unexpected lower bound: "//to_string(lbound(a, 1)))
+      call check(error, ubound(a, 1) == lb + n2 - 1, &
+                 "unexpected upper bound: "//to_string(ubound(a, 1)))
+      if (allocated(error)) return
+
+      ! set new array elements and check new/old contents
+      do i = lb + n1 - 1, lb + n2 - 1
+        a(i) = mod(i, 2) == 0
+      end do
+      do i = lb, lb + n2 - 1
+        call check(error, a(i) .eqv. (mod(i, 2) == 0), &
+                   "unexpected value "// &
+                   merge('t', 'f', a(i)) &
+                   //" at i="//to_string(i))
+        if (allocated(error)) return
+      end do
+      deallocate (a)
+    end do
+  end subroutine test_ExpandArray_lgp
+
+  !> @brief Test 2D int array expansion
+  subroutine test_ExpandArray2D_int(error)
+    type(error_type), allocatable, intent(out) :: error
+    integer(I4B), allocatable :: a(:, :)
+    integer(I4B) :: i, lb, n1, n2
+
+    n1 = 2 ! starting size
+    n2 = 5 ! expanded size
+    do lb = -1, 1 ! test with default lower bound (1) as well as 0 and -1
+      ! allocate/populate array and check initial size, with
+      ! same lower bound and starting/new size for both dims
+      allocate (a(lb:(lb + n1 - 1), lb:(lb + n1 - 1)))
+      a(lb, :) = lb
+      a(lb + 1, :) = lb + 1
+      call check(error, size(a, 1) == n1 .and. size(a, 2) == n1)
+      if (allocated(error)) return
+
+      ! resize array and check new size and bounds
+      call ExpandArray2D(a, n2 - n1, n2 - n1)
+      call check(error, size(a, 1) == n2, &
+                 "unexpected dim1 size: "//to_string(size(a, 1)))
+      call check(error, size(a, 1) == n2, &
+                 "unexpected dim2 size: "//to_string(size(a, 1)))
+      call check(error, lbound(a, 1) == lb, &
+                 "unexpected dim1 lower bound:"//to_string(lbound(a, 1)))
+      call check(error, ubound(a, 1) == lb + n2 - 1, &
+                 "unexpected dim1 upper bound:"//to_string(ubound(a, 1)))
+      call check(error, lbound(a, 2) == lb, &
+                 "unexpected dim2 lower bound:"//to_string(lbound(a, 2)))
+      call check(error, ubound(a, 2) == lb + n2 - 1, &
+                 "unexpected dim2 upper bound:"//to_string(ubound(a, 2)))
+      if (allocated(error)) return
+
+      ! set new elements starting from the new region, check new/old contents
+      do i = lb + n1 - 1, lb + n2 - 1
+        a(i, :) = i
+      end do
+      do i = lb, lb + n2 - 1
+        if (i < (lb + n1 - 1)) then
+          ! old contents, expect uninitialized values in new slots
+          call check(error, all(a(i, lb:(lb + n1 - 1)) == i), &
+                     "unexpected value "//to_string(a(i, i)) &
+                     //" at i="//to_string(i))
+        else
+          ! new contents, expect all values as set in prior loop
+          call check(error, all(a(i, :) == i), &
+                     "unexpected value "//to_string(a(i, i)) &
+                     //" at i="//to_string(i))
+        end if
+        if (allocated(error)) return
+      end do
+      deallocate (a)
+    end do
+  end subroutine test_ExpandArray2D_int
+
+  !> @brief Test 2D dbl array expansion
+  subroutine test_ExpandArray2D_dbl(error)
+    type(error_type), allocatable, intent(out) :: error
+    real(DP), allocatable :: a(:, :)
+    integer(I4B) :: i, lb, n1, n2
+
+    n1 = 2 ! starting size
+    n2 = 5 ! expanded size
+    do lb = -1, 1 ! test with default lower bound (1) as well as 0 and -1
+      ! allocate/populate array and check initial size, with
+      ! same lower bound and starting/new size for both dims
+      allocate (a(lb:(lb + n1 - 1), lb:(lb + n1 - 1)))
+      a(lb, :) = real(lb)
+      a(lb + 1, :) = real(lb + 1)
+      call check(error, size(a, 1) == n1 .and. size(a, 2) == n1)
+      if (allocated(error)) return
+
+      ! resize array and check new size and bounds
+      call ExpandArray2D(a, n2 - n1, n2 - n1)
+      call check(error, size(a, 1) == n2, &
+                 "unexpected dim1 size: "//to_string(size(a, 1)))
+      call check(error, size(a, 1) == n2, &
+                 "unexpected dim2 size: "//to_string(size(a, 1)))
+      call check(error, lbound(a, 1) == lb, &
+                 "unexpected dim1 lower bound:"//to_string(lbound(a, 1)))
+      call check(error, ubound(a, 1) == lb + n2 - 1, &
+                 "unexpected dim1 upper bound:"//to_string(ubound(a, 1)))
+      call check(error, lbound(a, 2) == lb, &
+                 "unexpected dim2 lower bound:"//to_string(lbound(a, 2)))
+      call check(error, ubound(a, 2) == lb + n2 - 1, &
+                 "unexpected dim2 upper bound:"//to_string(ubound(a, 2)))
+      if (allocated(error)) return
+
+      ! set new elements starting from the new region, check new/old contents
+      do i = lb + n1 - 1, lb + n2 - 1
+        a(i, :) = real(i)
+      end do
+      do i = lb, lb + n2 - 1
+        if (i < (lb + n1 - 1)) then
+          ! old contents, expect uninitialized values in new slots
+          call check(error, all(a(i, lb:(lb + n1 - 1)) == real(i)), &
+                     "unexpected value "//to_string(a(i, i)) &
+                     //" at i="//to_string(i))
+        else
+          ! new contents, expect all values as set in prior loop
+          call check(error, all(a(i, :) == real(i)), &
+                     "unexpected value "//to_string(a(i, i)) &
+                     //" at i="//to_string(i))
+        end if
+        if (allocated(error)) return
+      end do
+      deallocate (a)
+    end do
+  end subroutine test_ExpandArray2D_dbl
+
+  !> @brief Test 1D int ptr array expansion
+  subroutine test_ExtendPtrArray_int(error)
+    type(error_type), allocatable, intent(out) :: error
+    integer(I4B), allocatable, target :: aa(:)
+    integer(I4B), pointer, contiguous :: a(:)
+    integer(I4B) :: i, lb, n1, n2
+
+    n1 = 2 ! starting size
+    n2 = 5 ! expanded size
+    do lb = -1, 1 ! test with default lower bound (1) as well as 0 and -1
+      ! allocate/populate array and set pointer
+      allocate (aa(lb:(lb + n1 - 1)))
+      aa(lb) = lb
+      aa(lb + 1) = lb + 1
+      a => aa
+
+      ! resize array and check new size and bounds
+      call ExtendPtrArray(a, n2 - n1)
+      call check(error, size(a, 1) == n2, &
+                 "unexpected size: "//to_string(size(a, 1)))
+      call check(error, lbound(a, 1) == lb, &
+                 "unexpected lower bound: "//to_string(lbound(a, 1)))
+      call check(error, ubound(a, 1) == lb + n2 - 1, &
+                 "unexpected upper bound: "//to_string(ubound(a, 1)))
+      if (allocated(error)) return
+
+      ! set new array elements and check new/old contents
+      do i = lb + n1 - 1, lb + n2 - 1
+        a(i) = i
+      end do
+      do i = lb, lb + n2 - 1
+        call check(error, a(i) == i, &
+                   "unexpected value "//to_string(a(i)) &
+                   //" at i="//to_string(i))
+        if (allocated(error)) return
+      end do
+      nullify (a)
+      deallocate (aa)
+    end do
+  end subroutine test_ExtendPtrArray_int
+
+  !> @brief Test 1D dbl ptr array expansion
+  subroutine test_ExtendPtrArray_dbl(error)
+    type(error_type), allocatable, intent(out) :: error
+    real(DP), allocatable, target :: aa(:)
+    real(DP), pointer, contiguous :: a(:)
+    integer(I4B) :: i, lb, n1, n2
+
+    n1 = 2 ! starting size
+    n2 = 5 ! expanded size
+    do lb = -1, 1 ! test with default lower bound (1) as well as 0 and -1
+      ! allocate/populate array and set pointer
+      allocate (aa(lb:(lb + n1 - 1)))
+      aa(lb) = real(lb)
+      aa(lb + 1) = real(lb + 1)
+      a => aa
+
+      ! resize array and check new size and bounds
+      call ExtendPtrArray(a, n2 - n1)
+      call check(error, size(a, 1) == n2, &
+                 "unexpected size: "//to_string(size(a, 1)))
+      call check(error, lbound(a, 1) == lb, &
+                 "unexpected lower bound: "//to_string(lbound(a, 1)))
+      call check(error, ubound(a, 1) == lb + n2 - 1, &
+                 "unexpected upper bound: "//to_string(ubound(a, 1)))
+      if (allocated(error)) return
+
+      ! set new array elements and check new/old contents
+      do i = lb + n1 - 1, n2
+        a(i) = real(i)
+      end do
+      do i = lb, lb + n2 - 1
+        call check(error, a(i) == real(i), &
+                   "unexpected value "//to_string(a(i)) &
+                   //" at i="//to_string(i))
+        if (allocated(error)) return
+      end do
+      nullify (a)
+      deallocate (aa)
+    end do
+  end subroutine test_ExtendPtrArray_dbl
+
+  subroutine test_remove_character(error)
+    type(error_type), allocatable, intent(out) :: error
+    character(len=11), allocatable :: s(:)
+    allocate (s(2))
+    s(1) = "hello world"
+    s(2) = "hello earth"
+    call remove_character(s, 1)
+    call check(error, s(1) == "hello earth")
+  end subroutine test_remove_character
+
+end module TestArrayHandlers
diff --git a/autotest/TestDevFeature.f90 b/autotest/TestDevFeature.f90
new file mode 100644
index 00000000000..243c2e9e233
--- /dev/null
+++ b/autotest/TestDevFeature.f90
@@ -0,0 +1,28 @@
+module TestDevFeature
+  use testdrive, only: error_type, unittest_type, new_unittest, check
+  use DevFeatureModule, only: dev_feature
+  use ConstantsModule, only: LINELENGTH
+  use VersionModule, only: IDEVELOPMODE
+
+  implicit none
+  private
+  public :: collect_dev_feature
+
+contains
+
+  subroutine collect_dev_feature(testsuite)
+    type(unittest_type), allocatable, intent(out) :: testsuite(:)
+    testsuite = [ &
+                ! expect failure if in release mode, otherwise pass
+                new_unittest("dev_feature", test_dev_feature, &
+                             should_fail=(IDEVELOPMODE == 0)) &
+                ]
+  end subroutine collect_dev_feature
+
+  subroutine test_dev_feature(error)
+    type(error_type), allocatable, intent(out) :: error
+    character(len=LINELENGTH) :: errmsg
+    call dev_feature(errmsg)
+  end subroutine test_dev_feature
+
+end module TestDevFeature
diff --git a/autotest/TestGeomUtil.f90 b/autotest/TestGeomUtil.f90
new file mode 100644
index 00000000000..3447f8eb6e9
--- /dev/null
+++ b/autotest/TestGeomUtil.f90
@@ -0,0 +1,323 @@
+module TestGeomUtil
+  use KindModule, only: I4B, DP
+  use testdrive, only: check, error_type, new_unittest, test_failed, &
+                       to_string, unittest_type
+  use GeomUtilModule, only: get_node, get_ijk, get_jk, point_in_polygon, &
+                            skew
+  use ConstantsModule, only: LINELENGTH
+  implicit none
+  private
+  public :: collect_geomutil
+
+contains
+
+  subroutine collect_geomutil(testsuite)
+    type(unittest_type), allocatable, intent(out) :: testsuite(:)
+    testsuite = [ &
+                new_unittest("get_node_get_ijk", &
+                             test_get_node_get_ijk), &
+                new_unittest("point_in_polygon_sq", &
+                             test_point_in_polygon_sq), &
+                new_unittest("point_in_polygon_tri", &
+                             test_point_in_polygon_tri), &
+                new_unittest("point_in_polygon_irr", &
+                             test_point_in_polygon_irr), &
+                new_unittest("skew", test_skew) &
+                ]
+  end subroutine collect_geomutil
+
+  ! 2D arrays for polygons and check points use column-major indexing
+
+  subroutine test_get_node_get_ijk(error)
+    type(error_type), allocatable, intent(out) :: error
+    integer :: ilay
+    integer :: irow
+    integer :: icol
+    integer :: nlay
+    integer :: nrow
+    integer :: ncol
+    integer :: nnum
+    integer :: ncls
+    integer :: k, i, j
+
+    ! trivial grid with 1 cell
+    nnum = get_node(1, 1, 1, 1, 1, 1)
+    call get_ijk(nnum, 1, 1, 1, ilay, irow, icol)
+    call check(error, nnum == 1)
+    call check(error, ilay == 1)
+    call check(error, irow == 1)
+    call check(error, icol == 1)
+    if (allocated(error)) return
+
+    ! small grid, 3x4x5
+    nlay = 3
+    nrow = 4
+    ncol = 5
+    ncls = nlay * nrow * ncol
+    do k = 1, nlay
+      do i = 1, nrow
+        do j = 1, ncol
+          ! node number from ijk
+          nnum = get_node(k, i, j, nlay, nrow, ncol)
+          call check(error, nnum == (k - 1) * nrow * ncol + (i - 1) * ncol + j)
+          if (allocated(error)) return
+
+          ! ijk from node number
+          call get_ijk(nnum, nrow, ncol, nlay, irow, icol, ilay)
+          call check(error, ilay == k)
+          call check(error, irow == i)
+          call check(error, icol == j)
+          if (allocated(error)) return
+        end do
+      end do
+    end do
+  end subroutine test_get_node_get_ijk
+
+  subroutine test_point_in_polygon(error, shape, &
+                                   poly, in_pts, out_pts, vert_pts, face_pts)
+    type(error_type), allocatable, intent(inout) :: error
+    character(len=*), intent(in) :: shape
+    real(DP), allocatable, intent(in) :: poly(:, :)
+    real(DP), allocatable, intent(in) :: in_pts(:, :)
+    real(DP), allocatable, intent(in) :: out_pts(:, :)
+    real(DP), allocatable, intent(in) :: vert_pts(:, :)
+    real(DP), allocatable, intent(in) :: face_pts(:, :)
+    integer(I4B) :: i
+    real(DP) :: x, y
+
+    ! test inside points
+    do i = 1, size(in_pts, 2)
+      x = in_pts(1, i)
+      y = in_pts(2, i)
+      call check(error, point_in_polygon(x, y, poly), &
+                 "point inside "//shape//" failed: " &
+                 //to_string(x)//", "//to_string(y))
+      if (allocated(error)) return
+    end do
+
+    ! test outside points
+    do i = 1, size(out_pts, 2)
+      x = out_pts(1, i)
+      y = out_pts(2, i)
+      call check(error, (.not. point_in_polygon(x, y, poly)), &
+                 "point outside "//shape//" failed: " &
+                 //to_string(x)//", "//to_string(y))
+      if (allocated(error)) return
+    end do
+
+    ! test vertex points
+    do i = 1, size(vert_pts, 2)
+      x = vert_pts(1, i)
+      y = vert_pts(2, i)
+      call check(error, point_in_polygon(x, y, poly), &
+                 "point on "//shape//" vertex failed: " &
+                 //to_string(x)//", "//to_string(y))
+      if (allocated(error)) return
+    end do
+
+    ! test face points
+    do i = 1, size(face_pts, 2)
+      x = face_pts(1, i)
+      y = face_pts(2, i)
+      call check(error, point_in_polygon(x, y, poly), &
+                 "point on "//shape//" face failed: " &
+                 //to_string(x)//", "//to_string(y))
+      if (allocated(error)) return
+    end do
+  end subroutine test_point_in_polygon
+
+  !> @brief Test a unit square
+  subroutine test_point_in_polygon_sq(error)
+    type(error_type), allocatable, intent(out) :: error
+    real(DP), allocatable :: poly(:, :)
+    real(DP), allocatable :: in_pts(:, :)
+    real(DP), allocatable :: out_pts(:, :)
+    real(DP), allocatable :: vert_pts(:, :)
+    real(DP), allocatable :: face_pts(:, :)
+
+    allocate (poly(2, 4))
+
+    allocate (in_pts(2, 3))
+    in_pts(:, 1) = (/0.99_DP, 0.01_DP/)
+    in_pts(:, 2) = (/0.5_DP, 0.5_DP/)
+    in_pts(:, 3) = (/0.0001_DP, 0.9999_DP/)
+
+    allocate (out_pts(2, 2))
+    out_pts(:, 1) = (/0.5_DP, 1.00001_DP/)
+    out_pts(:, 2) = (/-0.5_DP, 34.0_DP/)
+
+    allocate (vert_pts(2, 4))
+    vert_pts(:, 1) = (/0.0_DP, 0.0_DP/)
+    vert_pts(:, 2) = (/1.0_DP, 0.0_DP/)
+    vert_pts(:, 3) = (/0.0_DP, 1.0_DP/)
+    vert_pts(:, 4) = (/1.0_DP, 1.0_DP/)
+
+    allocate (face_pts(2, 4))
+    face_pts(:, 1) = (/0.0_DP, 0.5_DP/)
+    face_pts(:, 2) = (/0.5_DP, 0.0_DP/)
+    face_pts(:, 3) = (/1.0_DP, 0.5_DP/)
+    face_pts(:, 4) = (/0.5_DP, 1.0_DP/)
+
+    poly(:, 1) = (/0.0_DP, 0.0_DP/)
+    poly(:, 2) = (/0.0_DP, 1.0_DP/)
+    poly(:, 3) = (/1.0_DP, 1.0_DP/)
+    poly(:, 4) = (/1.0_DP, 0.0_DP/)
+    call test_point_in_polygon(error, "clockwise square", &
+                               poly, in_pts, out_pts, vert_pts, face_pts)
+    if (allocated(error)) return
+
+    poly(:, 1) = (/0.0_DP, 0.0_DP/)
+    poly(:, 2) = (/1.0_DP, 0.0_DP/)
+    poly(:, 3) = (/1.0_DP, 1.0_DP/)
+    poly(:, 4) = (/0.0_DP, 1.0_DP/)
+    call test_point_in_polygon(error, "counter-clockwise square", &
+                               poly, in_pts, out_pts, vert_pts, face_pts)
+    if (allocated(error)) return
+
+    deallocate (poly)
+    deallocate (in_pts)
+    deallocate (out_pts)
+    deallocate (vert_pts)
+    deallocate (face_pts)
+  end subroutine test_point_in_polygon_sq
+
+  !> @brief Test a right triangle
+  subroutine test_point_in_polygon_tri(error)
+    type(error_type), allocatable, intent(out) :: error
+    real(DP), allocatable :: poly(:, :)
+    real(DP), allocatable :: in_pts(:, :)
+    real(DP), allocatable :: out_pts(:, :)
+    real(DP), allocatable :: vert_pts(:, :)
+    real(DP), allocatable :: face_pts(:, :)
+
+    allocate (poly(2, 3))
+
+    allocate (in_pts(2, 3))
+    in_pts(:, 1) = (/0.8_DP, 0.0001_DP/)
+    in_pts(:, 2) = (/0.5_DP, 0.49999_DP/)
+    in_pts(:, 3) = (/0.0001_DP, 0.8_DP/)
+
+    allocate (out_pts(2, 2))
+    out_pts(:, 1) = (/0.5_DP, 0.50001_DP/)
+    out_pts(:, 2) = (/-0.5_DP, 34.0_DP/)
+
+    allocate (vert_pts(2, 3))
+    vert_pts(:, 1) = (/0.0_DP, 0.0_DP/)
+    vert_pts(:, 2) = (/1.0_DP, 0.0_DP/)
+    vert_pts(:, 3) = (/0.0_DP, 1.0_DP/)
+
+    allocate (face_pts(2, 3))
+    face_pts(:, 1) = (/0.0_DP, 0.5_DP/)
+    face_pts(:, 2) = (/0.5_DP, 0.0_DP/)
+    face_pts(:, 3) = (/0.5_DP, 0.5_DP/)
+
+    poly(:, 1) = (/0.0_DP, 0.0_DP/)
+    poly(:, 2) = (/0.0_DP, 1.0_DP/)
+    poly(:, 3) = (/1.0_DP, 0.0_DP/)
+    call test_point_in_polygon(error, "clockwise triangle", &
+                               poly, in_pts, out_pts, vert_pts, face_pts)
+    if (allocated(error)) return
+
+    poly(:, 1) = (/0.0_DP, 0.0_DP/)
+    poly(:, 2) = (/1.0_DP, 0.0_DP/)
+    poly(:, 3) = (/0.0_DP, 1.0_DP/)
+    call test_point_in_polygon(error, "counter-clockwise triangle", &
+                               poly, in_pts, out_pts, vert_pts, face_pts)
+    if (allocated(error)) return
+
+    deallocate (poly)
+    deallocate (in_pts)
+    deallocate (out_pts)
+    deallocate (vert_pts)
+    deallocate (face_pts)
+  end subroutine test_point_in_polygon_tri
+
+  !> @brief Test an irregular polygon
+  subroutine test_point_in_polygon_irr(error)
+    type(error_type), allocatable, intent(out) :: error
+    real(DP), allocatable :: poly(:, :)
+    real(DP), allocatable :: in_pts(:, :)
+    real(DP), allocatable :: out_pts(:, :)
+    real(DP), allocatable :: vert_pts(:, :)
+    real(DP), allocatable :: face_pts(:, :)
+
+    allocate (poly(2, 5))
+
+    allocate (in_pts(2, 3))
+    in_pts(:, 1) = (/0.5_DP, 0.1_DP/)
+    in_pts(:, 2) = (/0.5_DP, 0.49_DP/)
+    in_pts(:, 3) = (/1.999_DP, 1.999_DP/)
+
+    allocate (out_pts(2, 3))
+    out_pts(:, 1) = (/0.5_DP, -0.1_DP/)
+    out_pts(:, 2) = (/0.5_DP, 0.51_DP/)
+    out_pts(:, 3) = (/-0.5_DP, 34.0_DP/)
+
+    allocate (vert_pts(2, 5))
+    vert_pts(:, 1) = (/0.0_DP, 0.0_DP/)
+    vert_pts(:, 2) = (/1.0_DP, 1.0_DP/)
+    vert_pts(:, 3) = (/1.0_DP, 2.0_DP/)
+    vert_pts(:, 4) = (/2.0_DP, 2.0_DP/)
+    vert_pts(:, 5) = (/2.0_DP, 0.0_DP/)
+
+    allocate (face_pts(2, 3))
+    face_pts(:, 1) = (/0.5_DP, 0.5_DP/)
+    face_pts(:, 2) = (/2.0_DP, 1.0_DP/)
+    face_pts(:, 3) = (/1.5_DP, 2.0_DP/)
+
+    poly(:, 1) = (/0.0_DP, 0.0_DP/)
+    poly(:, 2) = (/1.0_DP, 1.0_DP/)
+    poly(:, 3) = (/1.0_DP, 2.0_DP/)
+    poly(:, 4) = (/2.0_DP, 2.0_DP/)
+    poly(:, 5) = (/2.0_DP, 0.0_DP/)
+    call test_point_in_polygon(error, &
+                               "clockwise irregular polygon", &
+                               poly, in_pts, out_pts, vert_pts, face_pts)
+    if (allocated(error)) return
+
+    poly(:, 1) = (/0.0_DP, 0.0_DP/)
+    poly(:, 2) = (/2.0_DP, 0.0_DP/)
+    poly(:, 3) = (/2.0_DP, 2.0_DP/)
+    poly(:, 4) = (/1.0_DP, 2.0_DP/)
+    poly(:, 5) = (/1.0_DP, 1.0_DP/)
+    call test_point_in_polygon(error, &
+                               "counter-clockwise irregular polygon", &
+                               poly, in_pts, out_pts, vert_pts, face_pts)
+    if (allocated(error)) return
+
+    deallocate (poly)
+    deallocate (in_pts)
+    deallocate (out_pts)
+    deallocate (vert_pts)
+    deallocate (face_pts)
+  end subroutine test_point_in_polygon_irr
+
+  subroutine test_skew(error)
+    type(error_type), allocatable, intent(out) :: error
+    real(DP) :: v(2)
+
+    ! shear to right
+    v = (/1.0_DP, 1.0_DP/)
+    v = skew(v, (/1.0_DP, 1.0_DP, 1.0_DP/))
+    call check(error, v(1) == 2.0_DP .and. v(2) == 1.0_DP)
+    v = (/2.0_DP, 2.0_DP/)
+    v = skew(v, (/1.0_DP, 0.5_DP, 1.0_DP/))
+    call check(error, v(1) == 3.0_DP .and. v(2) == 2.0_DP)
+
+    ! collapse x dim
+    v = (/2.0_DP, 2.0_DP/)
+    v = skew(v, (/0.0_DP, 0.5_DP, 1.0_DP/))
+    call check(error, v(1) == 1.0_DP .and. v(2) == 2.0_DP, to_string(v(1)))
+
+    ! mirror over x axis
+    v = (/2.0_DP, 2.0_DP/)
+    v = skew(v, (/-1.0_DP, 0.0_DP, 1.0_DP/))
+    call check(error, v(1) == -2.0_DP .and. v(2) == 2.0_DP, to_string(v(1)))
+
+    ! mirror over x and y axis
+    v = (/2.0_DP, 2.0_DP/)
+    v = skew(v, (/-1.0_DP, 0.0_DP, -1.0_DP/))
+    call check(error, v(1) == -2.0_DP .and. v(2) == -2.0_DP, to_string(v(1)))
+  end subroutine test_skew
+
+end module TestGeomUtil
diff --git a/autotest/TestHashTable.f90 b/autotest/TestHashTable.f90
new file mode 100644
index 00000000000..5e20d853a9b
--- /dev/null
+++ b/autotest/TestHashTable.f90
@@ -0,0 +1,41 @@
+module TestHashTable
+  use KindModule, only: I4B, DP
+  use ConstantsModule, only: DNODATA, DZERO
+  use testdrive, only: check, error_type, new_unittest, test_failed, &
+                       to_string, unittest_type
+  use HashTableModule, only: HashTableType, hash_table_cr, hash_table_da
+  implicit none
+  private
+  public :: collect_hashtable
+
+contains
+
+  subroutine collect_hashtable(testsuite)
+    type(unittest_type), allocatable, intent(out) :: testsuite(:)
+    testsuite = [ &
+                new_unittest("add_and_get_value", &
+                             test_add_and_get_value) &
+                ]
+  end subroutine collect_hashtable
+
+  subroutine test_add_and_get_value(error)
+    type(error_type), allocatable, intent(out) :: error
+    type(HashTableType), pointer :: map
+    integer(I4B) :: i, n
+
+    allocate (map)
+    call hash_table_cr(map)
+
+    n = 3
+    do i = 1, n
+      call map%add(to_string(i), i)
+    end do
+
+    do i = 1, n
+      call check(error, map%get(to_string(i)) == i, &
+                 'wrong value for '//to_string(i))
+    end do
+
+  end subroutine test_add_and_get_value
+
+end module TestHashTable
diff --git a/autotest/TestInputOutput.f90 b/autotest/TestInputOutput.f90
new file mode 100644
index 00000000000..49ca3483321
--- /dev/null
+++ b/autotest/TestInputOutput.f90
@@ -0,0 +1,16 @@
+module TestInputOutput
+  use testdrive, only: error_type, unittest_type, new_unittest, check
+  use ConstantsModule, only: LINELENGTH
+  ! use InputOutputModule, only: ???
+  implicit none
+  private
+  public :: collect_inputoutput
+
+contains
+
+  subroutine collect_inputoutput(testsuite)
+    type(unittest_type), allocatable, intent(out) :: testsuite(:)
+    allocate (testsuite(0))
+  end subroutine collect_inputoutput
+
+end module TestInputOutput
diff --git a/autotest/TestList.f90 b/autotest/TestList.f90
new file mode 100644
index 00000000000..605460ec9d2
--- /dev/null
+++ b/autotest/TestList.f90
@@ -0,0 +1,254 @@
+module TestList
+  use KindModule, only: I4B
+  use testdrive, only: error_type, unittest_type, new_unittest, check
+  use ConstantsModule, only: LINELENGTH
+  use ListModule, only: ListType
+  implicit none
+  private
+  public :: collect_list
+
+  type :: IntNodeType
+    integer :: value
+  end type IntNodeType
+
+contains
+
+  subroutine collect_list(testsuite)
+    type(unittest_type), allocatable, intent(out) :: testsuite(:)
+    testsuite = [ &
+                new_unittest("add_count_get_item", &
+                             test_add_count_get_item), &
+                new_unittest("get_get_index_contains", &
+                             test_get_index_contains), &
+                new_unittest("get_next_previous_item_reset", &
+                             test_get_next_previous_item_reset), &
+                new_unittest("insert_after", &
+                             test_insert_after), &
+                new_unittest("remove_node", &
+                             test_remove_node) &
+                ]
+  end subroutine collect_list
+
+  subroutine test_add_count_get_item(error)
+    type(error_type), allocatable, intent(out) :: error
+    type(ListType), pointer :: list
+    type(IntNodeType), pointer :: n
+    class(*), pointer :: p
+
+    allocate (list)
+    allocate (n)
+
+    ! empty
+    call check(error, list%Count() == 0, "count should be 0")
+    if (allocated(error)) return
+
+    ! add one node
+    n%value = 1
+    p => n
+    call list%Add(p)
+
+    ! check count
+    call check(error, list%Count() == 1, "count should be 1")
+    if (allocated(error)) return
+
+    ! retrieve item
+    p => list%GetItem(1)
+    call check(error, associated(p, n))
+    select type (item => p)
+    type is (IntNodeType)
+      call check(error, item%value == 1, "wrong value")
+    class default
+      call check(error, .false., "wrong node type")
+    end select
+    if (allocated(error)) return
+
+    deallocate (list)
+    deallocate (n)
+  end subroutine test_add_count_get_item
+
+  subroutine test_get_index_contains(error)
+    type(error_type), allocatable, intent(out) :: error
+    type(ListType), pointer :: list
+    type(IntNodeType), pointer :: n1, n2
+    class(*), pointer :: p
+    integer(I4B) :: i
+
+    allocate (list)
+    allocate (n1)
+    allocate (n2)
+
+    ! add nodes
+    n1%value = 1
+    n2%value = 2
+    p => n1
+    call list%Add(p)
+    p => n2
+    call list%Add(p)
+
+    ! check count
+    call check(error, list%Count() == 2, "count should be 1")
+    if (allocated(error)) return
+
+    ! check get index
+    i = list%GetIndex(p)
+    call check(error, i == 2, "wrong index")
+    if (allocated(error)) return
+
+    ! check contains
+    p => n1
+    call check(error, list%ContainsObject(p), "should contain n1")
+    if (allocated(error)) return
+    p => n2
+    call check(error, list%ContainsObject(p), "should contain n2")
+    if (allocated(error)) return
+
+    deallocate (list)
+    deallocate (n1)
+    deallocate (n2)
+  end subroutine test_get_index_contains
+
+  subroutine test_get_next_previous_item_reset(error)
+    type(error_type), allocatable, intent(out) :: error
+    type(ListType), pointer :: list
+    type(IntNodeType), pointer :: n1, n2, n3
+    class(*), pointer :: p
+    integer(I4B) :: i
+
+    allocate (list)
+    allocate (n1)
+    allocate (n2)
+    allocate (n3)
+
+    ! add nodes
+    n1%value = 1
+    n2%value = 2
+    n3%value = 3
+    p => n1
+    call list%Add(p)
+    p => n2
+    call list%Add(p)
+    p => n3
+    call list%Add(p)
+
+    ! check count
+    call check(error, list%Count() == 3, "count should be 3")
+    if (allocated(error)) return
+
+    ! check get next/previous item
+    p => list%GetNextItem()
+    call check(error, associated(p, n1))
+    p => list%GetNextItem()
+    call check(error, associated(p, n2))
+    p => list%GetPreviousItem()
+    call check(error, associated(p, n1))
+    p => list%GetNextItem()
+    call check(error, associated(p, n2))
+    p => list%GetNextItem()
+    call check(error, associated(p, n3))
+    p => list%GetNextItem()
+    call check(error, (.not. associated(p)))
+    call list%Reset()
+    p => list%GetPreviousItem()
+    call check(error, (.not. associated(p)))
+
+    deallocate (list)
+    deallocate (n1)
+    deallocate (n2)
+    deallocate (n3)
+  end subroutine test_get_next_previous_item_reset
+
+  subroutine test_insert_after(error)
+    type(error_type), allocatable, intent(out) :: error
+    type(ListType), pointer :: list
+    type(IntNodeType), pointer :: n1, n2, n3
+    class(*), pointer :: p
+
+    allocate (list)
+    allocate (n1)
+    allocate (n2)
+    allocate (n3)
+
+    ! add nodes 1 and 3
+    n1%value = 1
+    n2%value = 2
+    n3%value = 3
+    p => n1
+    call list%Add(p)
+    p => n3
+    call list%Add(p)
+
+    ! check count
+    call check(error, list%Count() == 2, "count should be 2")
+    if (allocated(error)) return
+
+    ! insert item after first item
+    p => n2
+    call list%InsertAfter(p, 1)
+
+    ! check count
+    call check(error, list%Count() == 3, "count should be 3")
+    if (allocated(error)) return
+
+    ! check get next/previous item
+    call list%Reset()
+    p => list%GetNextItem()
+    call check(error, associated(p, n1))
+    p => list%GetNextItem()
+    call check(error, associated(p, n2))
+    p => list%GetNextItem()
+    call check(error, associated(p, n3))
+    if (allocated(error)) return
+
+    deallocate (list)
+    deallocate (n1)
+    deallocate (n2)
+    deallocate (n3)
+  end subroutine test_insert_after
+
+  subroutine test_remove_node(error)
+    type(error_type), allocatable, intent(out) :: error
+    type(ListType), pointer :: list
+    type(IntNodeType), pointer :: n1, n2, n3
+    class(*), pointer :: p
+
+    allocate (list)
+    allocate (n1)
+    allocate (n2)
+    allocate (n3)
+
+    ! add nodes
+    n1%value = 1
+    n2%value = 2
+    n3%value = 3
+    p => n1
+    call list%Add(p)
+    p => n2
+    call list%Add(p)
+    p => n3
+    call list%Add(p)
+
+    ! check count
+    call check(error, list%Count() == 3, "count should be 3")
+    if (allocated(error)) return
+
+    ! remove first node
+    call list%RemoveNode(1, .false.)
+    call check(error, list%Count() == 2, "count should be 2")
+    p => list%GetItem(1)
+    call check(error, associated(p, n2))
+    p => list%GetItem(2)
+    call check(error, associated(p, n3))
+
+    ! remove last node
+    call list%RemoveNode(2, .false.)
+    call check(error, list%Count() == 1, "count should be 1")
+    p => list%GetItem(1)
+    call check(error, associated(p, n2))
+
+    deallocate (list)
+    deallocate (n1)
+    deallocate (n2)
+    deallocate (n3)
+  end subroutine test_remove_node
+
+end module TestList
diff --git a/autotest/TestMathUtil.f90 b/autotest/TestMathUtil.f90
new file mode 100644
index 00000000000..a07ad0af55c
--- /dev/null
+++ b/autotest/TestMathUtil.f90
@@ -0,0 +1,243 @@
+module TestMathUtil
+  use KindModule, only: I4B, DP
+  use ConstantsModule, only: DNODATA, DZERO
+  use testdrive, only: check, error_type, new_unittest, test_failed, &
+                       to_string, unittest_type
+  use MathUtilModule, only: f1d, is_close, mod_offset, &
+                            zeroch, zerotest, zeroin
+  implicit none
+  private
+  public :: collect_mathutil
+
+contains
+
+  subroutine collect_mathutil(testsuite)
+    type(unittest_type), allocatable, intent(out) :: testsuite(:)
+    testsuite = [ &
+                new_unittest("is_close_symmetric", test_is_close_symmetric), &
+                new_unittest("is_close_symmetric_near_0", &
+                             test_is_close_symmetric_near_0), &
+                new_unittest("mod_offset", &
+                             test_mod_offset), &
+                new_unittest("zeroch", &
+                             test_zeroch), &
+                new_unittest("zeroin", &
+                             test_zeroin), &
+                new_unittest("zerotest", &
+                             test_zerotest) &
+                ]
+  end subroutine collect_mathutil
+
+  subroutine test_mod_offset(error)
+    type(error_type), allocatable, intent(out) :: error
+
+    ! with no offset specified, should behave just like mod
+    call check(error, mod_offset(2, 2) == 0)
+    call check(error, mod_offset(2, 3) == 2)
+    call check(error, mod_offset(2.0_DP, 2.0_DP) == 0.0_DP)
+    call check(error, mod_offset(2.0_DP, 3.0_DP) == 2.0_DP)
+
+    ! with offset d specified, if the result x = a mod n falls
+    ! between 0 and n - 1, the new result x = a mod_d n falls
+    ! between d and d + n - 1.
+    call check(error, mod_offset(2, 3, -2) == -1)
+    call check(error, mod_offset(2, 3, -1) == -1)
+    call check(error, mod_offset(2, 3, 0) == 2)
+    call check(error, mod_offset(2, 3, 1) == 2)
+    call check(error, mod_offset(2, 3, 2) == 2)
+    call check(error, mod_offset(2, 3, 3) == 5)
+    call check(error, mod_offset(2, 3, 4) == 5)
+    call check(error, mod_offset(2.0_DP, 3.0_DP, -1.0_DP) == -1.0_DP)
+    call check(error, mod_offset(2.0_DP, 3.0_DP, 2.0_DP) == 2.0_DP)
+    call check(error, mod_offset(2.0_DP, 3.0_DP, 3.0_DP) == 5.0_DP)
+  end subroutine test_mod_offset
+
+  subroutine test_is_close_symmetric(error)
+    type(error_type), allocatable, intent(out) :: error
+    real(DP) :: a, b, rtol
+
+    ! exact match
+    a = 1.0_DP
+    b = 1.0_DP
+    call check(error, is_close(a, b), &
+               "exp eq: a="//to_string(a)// &
+               ", b="//to_string(b)// &
+               ", eps=default")
+    if (allocated(error)) return
+
+    ! mismatch with default rtol
+    b = 1.0001_DP
+    call check(error, (.not. (is_close(a, b))), &
+               "exp ne: a="//to_string(a)// &
+               ", b="//to_string(b)// &
+               ", eps=default")
+    if (allocated(error)) return
+
+    ! inexact match with large rtol
+    rtol = 1d-2
+    call check(error, is_close(a, b, rtol=rtol), &
+               "exp eq: a="//to_string(a)// &
+               ", b="//to_string(b)// &
+               ", rtol="//to_string(rtol))
+    if (allocated(error)) return
+
+    ! mismatch when we reduce rtol
+    rtol = 0.5d-5
+    call check(error, (.not. is_close(a, b, rtol=rtol)), &
+               "exp ne: a="//to_string(a)// &
+               ", b="//to_string(b)// &
+               ", rtol="//to_string(rtol))
+    if (allocated(error)) return
+
+    ! +/-0
+    call check(error, is_close(0.0_DP, -0.0_DP), &
+               "exp ne: a="//to_string(a)// &
+               ", b="//to_string(b)// &
+               ", eps=default")
+
+    ! DNODATA
+    call check(error, (.not. is_close(0.0_DP, DNODATA)), &
+               "exp ne: a="//to_string(a)// &
+               ", b="//to_string(b)// &
+               ", eps=default")
+    call check(error, is_close(DNODATA, DNODATA), &
+               "exp ne: a="//to_string(a)// &
+               ", b="//to_string(b)// &
+               ", eps=default")
+    call check(error, (.not. is_close(DNODATA, DNODATA / 10)), &
+               "exp ne: a="//to_string(a)// &
+               ", b="//to_string(b)// &
+               ", eps=default")
+    call check(error, (.not. is_close(DNODATA, DNODATA * 10)), &
+               "exp ne: a="//to_string(a)// &
+               ", b="//to_string(b)// &
+               ", eps=default")
+
+  end subroutine test_is_close_symmetric
+
+  subroutine test_is_close_symmetric_near_0(error)
+    type(error_type), allocatable, intent(out) :: error
+    real(DP) :: a, b, rtol, atol
+
+    a = 0.0_DP
+    b = 0.0_DP
+    call check(error, is_close(a, b), &
+               "exp eq: a="//to_string(a)// &
+               ", b="//to_string(b)// &
+               ", rtol=default")
+    if (allocated(error)) return
+
+    a = DZERO
+    b = DZERO
+    call check(error, is_close(a, b), &
+               "exp eq: a="//to_string(a)// &
+               ", b="//to_string(b)// &
+               ", rtol=default")
+    if (allocated(error)) return
+
+    b = 1d-4
+    call check(error, (.not. is_close(a, b)), &
+               "exp eq: a="//to_string(a)// &
+               ", b="//to_string(b)// &
+               ", rtol=default")
+    if (allocated(error)) return
+
+    rtol = 0.999_DP
+    call check(error, &
+               ! expect failure, see above
+               (.not. is_close(a, b, rtol=rtol)), &
+               "exp eq: a="//to_string(a)// &
+               ", b="//to_string(b)// &
+               ", rtol="//to_string(rtol))
+    if (allocated(error)) return
+
+    ! absolute comparison is appropriate when a and/or b are near or equal to 0
+    b = 1d-4
+    atol = 1d-3
+    call check(error, is_close(a, b, atol=atol), &
+               "exp eq: a="//to_string(a)// &
+               ", b="//to_string(b)// &
+               ", atol="//to_string(atol))
+    if (allocated(error)) return
+
+    ! make sure the absolute tolerance is applied
+    b = 1d-4
+    atol = 1d-5
+    call check(error, (.not. is_close(a, b, atol=atol)), &
+               "exp eq: a="//to_string(a)// &
+               ", b="//to_string(b)// &
+               ", atol="//to_string(atol))
+    if (allocated(error)) return
+
+  end subroutine test_is_close_symmetric_near_0
+
+  pure function sine(bet) result(s)
+    real(DP), intent(in) :: bet
+    real(DP) :: s
+    s = sin(bet)
+  end function sine
+
+  subroutine test_zeroch(error)
+    type(error_type), allocatable, intent(out) :: error
+    real(DP), parameter :: pi = 4 * atan(1.0_DP)
+    real(DP) :: z
+    procedure(f1d), pointer :: f
+
+    f => sine
+
+    z = zeroch(-1.0_DP, 1.0_DP, f, 0.001_DP)
+    call check(error, is_close(z, 0.0_DP, atol=1d-6), &
+               'expected 0, got: '//to_string(z))
+
+    z = zeroch(-4.0_DP, -1.0_DP, f, 0.001_DP)
+    call check(error, is_close(z, -pi, atol=1d-6), &
+               'expected -pi, got: '//to_string(z))
+
+    z = zeroch(1.0_DP, 4.0_DP, f, 0.001_DP)
+    call check(error, is_close(z, pi, atol=1d-6), &
+               'expected pi, got: '//to_string(z))
+  end subroutine test_zeroch
+
+  subroutine test_zeroin(error)
+    type(error_type), allocatable, intent(out) :: error
+    real(DP), parameter :: pi = 4 * atan(1.0_DP)
+    real(DP) :: z
+    procedure(f1d), pointer :: f
+
+    f => sine
+
+    z = zeroin(-1.0_DP, 1.0_DP, f, 0.001_DP)
+    call check(error, is_close(z, 0.0_DP, atol=1d-6), &
+               'expected 0, got: '//to_string(z))
+
+    z = zeroin(-4.0_DP, -1.0_DP, f, 0.001_DP)
+    call check(error, is_close(z, -pi, atol=1d-6), &
+               'expected -pi, got: '//to_string(z))
+
+    z = zeroin(1.0_DP, 4.0_DP, f, 0.001_DP)
+    call check(error, is_close(z, pi, atol=1d-6), &
+               'expected pi, got: '//to_string(z))
+  end subroutine test_zeroin
+
+  subroutine test_zerotest(error)
+    type(error_type), allocatable, intent(out) :: error
+    real(DP), parameter :: pi = 4 * atan(1.0_DP)
+    real(DP) :: z
+    procedure(f1d), pointer :: f
+
+    f => sine
+
+    z = zerotest(-1.0_DP, 1.0_DP, f, 0.001_DP)
+    call check(error, is_close(z, 0.0_DP, atol=1d-6), &
+               'expected 0, got: '//to_string(z))
+
+    z = zerotest(-4.0_DP, -1.0_DP, f, 0.001_DP)
+    call check(error, is_close(z, -pi, atol=1d-6), &
+               'expected -pi, got: '//to_string(z))
+
+    z = zerotest(1.0_DP, 4.0_DP, f, 0.001_DP)
+    call check(error, is_close(z, pi, atol=1d-6), &
+               'expected pi, got: '//to_string(z))
+  end subroutine test_zerotest
+
+end module TestMathUtil
diff --git a/autotest/TestMessage.f90 b/autotest/TestMessage.f90
new file mode 100644
index 00000000000..b78d490df5b
--- /dev/null
+++ b/autotest/TestMessage.f90
@@ -0,0 +1,41 @@
+module TestMessage
+  use testdrive, only: error_type, unittest_type, new_unittest, check
+  use MessageModule, only: MessagesType
+  use ConstantsModule, only: LINELENGTH
+
+  implicit none
+  private
+  public :: collect_message
+
+contains
+
+  subroutine collect_message(testsuite)
+    type(unittest_type), allocatable, intent(out) :: testsuite(:)
+    testsuite = [ &
+                new_unittest("init_and_count", test_init_and_count), &
+                new_unittest("store_count_and_write_all", &
+                             test_store_count_and_write_all) &
+                ]
+  end subroutine collect_message
+
+  subroutine test_init_and_count(error)
+    type(error_type), allocatable, intent(out) :: error
+    type(MessagesType) :: messages
+    messages = MessagesType()
+    call messages%init()
+    call check(error, messages%count() == 0)
+  end subroutine test_init_and_count
+
+  subroutine test_store_count_and_write_all(error)
+    type(error_type), allocatable, intent(out) :: error
+    type(MessagesType) :: messages
+    messages = MessagesType()
+    call messages%init()
+    call messages%store("1")
+    call messages%store("2")
+    call check(error, messages%count() == 2)
+    ! debug visually with e.g. `meson test --no-rebuild -C builddir --verbose Message`
+    call messages%write_all()
+  end subroutine test_store_count_and_write_all
+
+end module TestMessage
diff --git a/autotest/TestSim.f90 b/autotest/TestSim.f90
new file mode 100644
index 00000000000..b01b9ea93a8
--- /dev/null
+++ b/autotest/TestSim.f90
@@ -0,0 +1,58 @@
+module TestSim
+  use testdrive, only: error_type, unittest_type, new_unittest, check
+  use SimModule, only: store_error, store_warning, store_note, &
+                       initial_message, count_errors, count_notes, &
+                       count_warnings
+  use ConstantsModule, only: LINELENGTH
+
+  implicit none
+  private
+  public :: collect_sim
+
+contains
+
+  subroutine collect_sim(testsuite)
+    type(unittest_type), allocatable, intent(out) :: testsuite(:)
+    testsuite = [ &
+                new_unittest("store_and_count", test_store_and_count) &
+                ]
+  end subroutine collect_sim
+
+  subroutine test_store_and_count(error)
+    type(error_type), allocatable, intent(out) :: error
+    character(len=LINELENGTH) :: ntemsg
+    character(len=LINELENGTH) :: wrnmsg
+    character(len=LINELENGTH) :: errmsg
+
+    ! define messages
+    ntemsg = "NOTE"
+    wrnmsg = "WARNING"
+    errmsg = "ERROR"
+
+    ! initialize message arrays
+    call initial_message()
+
+    ! check no messages stored
+    call check(error, count_errors() == 0)
+    call check(error, count_warnings() == 0)
+    call check(error, count_notes() == 0)
+    if (allocated(error)) return
+
+    ! todo store a note and check that it's stored
+    call store_note(ntemsg)
+    call check(error, count_notes() == 1)
+    if (allocated(error)) return
+
+    ! todo store a warning and check that it's stored
+    call store_warning(wrnmsg)
+    call check(error, count_warnings() == 1)
+    if (allocated(error)) return
+
+    ! store an error and check that it's stored
+    call store_error(errmsg, terminate=.false.)
+    call check(error, count_errors() == 1)
+    if (allocated(error)) return
+
+  end subroutine test_store_and_count
+
+end module TestSim
diff --git a/autotest/build_exes.py b/autotest/build_exes.py
index ede1d7a67e7..bd7125bd478 100644
--- a/autotest/build_exes.py
+++ b/autotest/build_exes.py
@@ -2,9 +2,10 @@
 from pathlib import Path
 
 import pytest
-from conftest import project_root_path
 from modflow_devtools.build import meson_build
 
+from conftest import project_root_path
+
 repository = "MODFLOW-USGS/modflow6"
 top_bin_path = project_root_path / "bin"
 
diff --git a/autotest/build_mfio_tex.py b/autotest/build_mfio_tex.py
index ab57f2da85d..aca75f8e242 100644
--- a/autotest/build_mfio_tex.py
+++ b/autotest/build_mfio_tex.py
@@ -49,7 +49,6 @@ def test_rebuild_from_dfn():
     pth = "./"
 
     with cwd(npth):
-
         # get list of TeX files
         files = [
             f
diff --git a/autotest/common_regression.py b/autotest/common_regression.py
index a167d9235ee..a1307adc23f 100644
--- a/autotest/common_regression.py
+++ b/autotest/common_regression.py
@@ -1,8 +1,31 @@
 import os
 import shutil
-import sys
-
-ignore_ext = (
+from pathlib import Path
+from typing import Iterator, List, Optional, Tuple, Union
+from warnings import warn
+
+import numpy as np
+from flopy.utils import CellBudgetFile
+from flopy.utils.compare import compare_heads
+
+COMPARE_PROGRAMS = (
+    "mf2005",
+    "mfnwt",
+    "mfusg",
+    "mflgr",
+    "libmf6",
+    "mf6",
+    "mf6_regression"
+    # todo: "mp7"
+)
+EXTTEXT = {
+    "hds": "head",
+    "hed": "head",
+    "bhd": "head",
+    "ucn": "concentration",
+    "cbc": "cell-by-cell",
+}
+IGNORE_EXTENSIONS = (
     ".hds",
     ".hed",
     ".bud",
@@ -19,185 +42,64 @@
 )
 
 
-def model_setup(namefile, dst, remove_existing=True, extrafiles=None):
-    """Setup MODFLOW-based model files for autotests.
-
-    Parameters
-    ----------
-    namefile : str
-        MODFLOW-based model name file.
-    dst : str
-        destination path for comparison model or file(s)
-    remove_existing : bool
-        boolean indicating if an existing comparision model or file(s) should
-        be replaced (default is True)
-    extrafiles : str or list of str
-        list of extra files to include in the comparision
-
-    Returns
-    -------
-
-    """
-    # Construct src pth from namefile or lgr file
-    src = os.path.dirname(namefile)
-
-    # Create the destination folder, if required
-    create_dir = False
-    if os.path.exists(dst):
-        if remove_existing:
-            print("Removing folder " + dst)
-            shutil.rmtree(dst)
-            create_dir = True
-    else:
-        create_dir = True
-    if create_dir:
-        os.mkdir(dst)
-
-    # determine if a namefile is a lgr control file - get individual
-    # name files out of the lgr control file
-    namefiles = [namefile]
-    ext = os.path.splitext(namefile)[1]
-    if ".lgr" in ext.lower():
-        lines = [line.rstrip("\n") for line in open(namefile)]
-        for line in lines:
-            if len(line) < 1:
-                continue
-            if line[0] == "#":
-                continue
-            t = line.split()
-            if ".nam" in t[0].lower():
-                fpth = os.path.join(src, t[0])
-                namefiles.append(fpth)
-
-    # Make list of files to copy
-    files2copy = []
-    for fpth in namefiles:
-        files2copy.append(os.path.basename(fpth))
-        ext = os.path.splitext(fpth)[1]
-        # copy additional files contained in the name file and
-        # associated package files
-        if ext.lower() == ".nam":
-            fname = os.path.abspath(fpth)
-            files2copy = files2copy + get_input_files(fname)
-
-    if extrafiles is not None:
-        if isinstance(extrafiles, str):
-            extrafiles = [extrafiles]
-        for fl in extrafiles:
-            files2copy.append(os.path.basename(fl))
-
-    # Copy the files
-    for f in files2copy:
-        srcf = os.path.join(src, f)
-        dstf = os.path.join(dst, f)
-
-        # Check to see if dstf is going into a subfolder, and create that
-        # subfolder if it doesn't exist
-        sf = os.path.dirname(dstf)
-        if not os.path.isdir(sf):
-            os.makedirs(sf)
-
-        # Now copy the file
-        if os.path.exists(srcf):
-            print("Copy file '" + srcf + "' -> '" + dstf + "'")
-            shutil.copy(srcf, dstf)
-        else:
-            print(srcf + " does not exist")
-
-    return
-
-
-def setup_comparison(namefile, dst, remove_existing=True):
-    """Setup a comparison model or comparision file(s) for a MODFLOW-based
-    model.
+def adjust_htol(
+    workspace: Union[str, os.PathLike], htol: float = 0.001
+) -> Optional[float]:
+    """Get outer_dvclose value from MODFLOW 6 ims file"""
+
+    dvclose = get_dvclose(workspace)
+    if not dvclose:
+        return htol
+
+    # adjust htol if < IMS outer_dvclose
+    dvclose *= 5.0
+    return dvclose if (htol is None or htol < dvclose) else htol
+
+
+def get_dvclose(workspace: Union[str, os.PathLike]) -> Optional[float]:
+    """Get outer_dvclose value from MODFLOW 6 ims file"""
+    dvclose = None
+    files = os.listdir(workspace)
+    for file_name in files:
+        pth = os.path.join(workspace, file_name)
+        if os.path.isfile(pth):
+            if file_name.lower().endswith(".ims"):
+                with open(pth) as f:
+                    lines = f.read().splitlines()
+                for line in lines:
+                    if "outer_dvclose" in line.lower():
+                        v = float(line.split()[1])
+                        if dvclose is None:
+                            dvclose = v
+                        else:
+                            if v > dvclose:
+                                dvclose = v
+                        break
 
-    Parameters
-    ----------
-    namefile : str
-        MODFLOW-based model name file.
-    dst : str
-        destination path for comparison model or file(s)
-    remove_existing : bool
-        boolean indicating if an existing comparision model or file(s) should
-        be replaced (default is True)
+    return dvclose
 
 
-    Returns
-    -------
+def get_rclose(workspace: Union[str, os.PathLike]) -> Optional[float]:
+    """Get inner_rclose value from MODFLOW 6 ims file"""
 
-    """
-    # Construct src pth from namefile
-    src = os.path.dirname(namefile)
-    action = None
-    for root, dirs, files in os.walk(src):
-        dl = [d.lower() for d in dirs]
-        if any(".cmp" in s for s in dl):
-            idx = None
-            for jdx, d in enumerate(dl):
-                if ".cmp" in d:
-                    idx = jdx
-                    break
-            if idx is not None:
-                if "mf2005.cmp" in dl[idx] or "mf2005" in dl[idx]:
-                    action = dirs[idx]
-                elif "mfnwt.cmp" in dl[idx] or "mfnwt" in dl[idx]:
-                    action = dirs[idx]
-                elif "mfusg.cmp" in dl[idx] or "mfusg" in dl[idx]:
-                    action = dirs[idx]
-                elif "mf6.cmp" in dl[idx] or "mf6" in dl[idx]:
-                    action = dirs[idx]
-                elif "libmf6.cmp" in dl[idx] or "libmf6" in dl[idx]:
-                    action = dirs[idx]
-                else:
-                    action = dirs[idx]
-                break
-    if action is not None:
-        dst = os.path.join(dst, f"{action}")
-        if not os.path.isdir(dst):
-            try:
-                os.mkdir(dst)
-            except:
-                print("Could not make " + dst)
-        # clean directory
-        else:
-            print(f"cleaning...{dst}")
-            for root, dirs, files in os.walk(dst):
-                for f in files:
-                    tpth = os.path.join(root, f)
-                    print(f"  removing...{tpth}")
-                    os.remove(tpth)
-                for d in dirs:
-                    tdir = os.path.join(root, d)
-                    print(f"  removing...{tdir}")
-                    shutil.rmtree(tdir)
-        # copy files
-        cmppth = os.path.join(src, action)
-        files = os.listdir(cmppth)
-        files2copy = []
-        if action.lower() == ".cmp":
-            for file in files:
-                if ".cmp" in os.path.splitext(file)[1].lower():
-                    files2copy.append(os.path.join(cmppth, file))
-            for srcf in files2copy:
-                f = os.path.basename(srcf)
-                dstf = os.path.join(dst, f)
-                # Now copy the file
-                if os.path.exists(srcf):
-                    print("Copy file '" + srcf + "' -> '" + dstf + "'")
-                    shutil.copy(srcf, dstf)
-                else:
-                    print(srcf + " does not exist")
-        else:
-            for file in files:
-                if ".nam" in os.path.splitext(file)[1].lower():
-                    files2copy.append(
-                        os.path.join(cmppth, os.path.basename(file))
-                    )
-                    nf = os.path.join(src, action, os.path.basename(file))
-                    model_setup(nf, dst, remove_existing=remove_existing)
+    rclose = None
+    for pth in workspace.glob("*.ims"):
+        with open(pth, "r") as f:
+            for line in f:
+                if "inner_rclose" in line.lower():
+                    v = float(line.split()[1])
+                    if rclose is None:
+                        rclose = v
+                    else:
+                        if v > rclose:
+                            rclose = v
                     break
 
-    return action
+    if rclose is None:
+        return 0.5
+
+    rclose *= 5.0
+    return rclose
 
 
 def get_input_files(namefile):
@@ -227,7 +129,7 @@ def get_input_files(namefile):
         if line.strip()[0] in ["#", "!"]:
             continue
         ext = os.path.splitext(ll[2])[1]
-        if ext.lower() not in ignore_ext:
+        if ext.lower() not in IGNORE_EXTENSIONS:
             if len(ll) > 3:
                 if "replace" in ll[3].lower():
                     continue
@@ -242,7 +144,6 @@ def get_input_files(namefile):
         try:
             f = open(fname, "r")
             for line in f:
-
                 # Skip invalid lines
                 ll = line.strip().split()
                 if len(ll) < 2:
@@ -259,7 +160,7 @@ def get_input_files(namefile):
                             otherfiles.append(stmp)
                             break
         except:
-            print(fname + " does not exist")
+            print(f"{fname} does not exist")
 
     filelist = filelist + otherfiles
 
@@ -302,132 +203,38 @@ def get_namefiles(pth, exclude=None):
     return namefiles
 
 
-def get_sim_name(namefiles, rootpth=None):
-    """Get simulation name.
-
-    Parameters
-    ----------
-    namefiles : str or list of strings
-        path(s) to MODFLOW-based model name files
-    rootpth : str
-        optional root directory path (default is None)
-
-    Returns
-    -------
-    simname : list
-        list of namefiles without the file extension
-
+def get_matching_files(
+    workspace: Union[str, os.PathLike], extensions: Union[str, Iterator[str]]
+) -> Iterator[str]:
     """
-    if isinstance(namefiles, str):
-        namefiles = [namefiles]
-    sim_name = []
-    for namefile in namefiles:
-        t = namefile.split(os.sep)
-        if rootpth is None:
-            idx = -1
-        else:
-            idx = t.index(os.path.split(rootpth)[1])
-
-        # build dst with everything after the rootpth and before
-        # the namefile file name.
-        dst = ""
-        if idx < len(t):
-            for d in t[idx + 1 : -1]:
-                dst += f"{d}_"
-
-        # add namefile basename without extension
-        dst += t[-1].replace(".nam", "")
-        sim_name.append(dst)
-
-    return sim_name
-
-
-def setup_mf6(
-    src, dst, mfnamefile="mfsim.nam", extrafiles=None, remove_existing=True
-):
-    """Copy all of the MODFLOW 6 input files from the src directory to the dst
-    directory.
-
+    Get MF6 regression files in the specified workspace,
+    optionally filtering by one or more file extensions.
     Parameters
     ----------
-    src : src
-        directory path with original MODFLOW 6 input files
-    dst : str
-        directory path that original MODFLOW 6 input files will be copied to
-    mfnamefile : str
-        optional MODFLOW 6 simulation name file (default is mfsim.nam)
-    extrafiles : bool
-        boolean indicating if extra files should be included (default is None)
-    remove_existing : bool
-        boolean indicating if existing file in dst should be removed (default
-        is True)
-
+    workspace : str or PathLike
+        MODFLOW 6 simulation workspace path
+    extensions : str or list of str
+        file extensions to filter
     Returns
     -------
-    mf6inp : list
-        list of MODFLOW 6 input files
-    mf6outp : list
-        list of MODFLOW 6 output files
-
+    An iterator of regression files found
     """
 
-    # Create the destination folder
-    create_dir = False
-    if os.path.exists(dst):
-        if remove_existing:
-            print("Removing folder " + dst)
-            shutil.rmtree(dst)
-            create_dir = True
-    else:
-        create_dir = True
-    if create_dir:
-        os.makedirs(dst)
+    workspace = Path(workspace).expanduser().absolute()
+    if isinstance(extensions, str):
+        extensions = [extensions]
 
-    # Make list of files to copy
-    fname = os.path.join(src, mfnamefile)
-    fname = os.path.abspath(fname)
-    mf6inp, mf6outp = get_mf6_files(fname)
-    files2copy = [mfnamefile] + mf6inp
-
-    # determine if there are any .ex files
-    exinp = []
-    for f in mf6outp:
-        ext = os.path.splitext(f)[1]
-        if ext.lower() == ".hds":
-            pth = os.path.join(src, f + ".ex")
-            if os.path.isfile(pth):
-                exinp.append(f + ".ex")
-    if len(exinp) > 0:
-        files2copy += exinp
-    if extrafiles is not None:
-        files2copy += extrafiles
-
-    # Copy the files
-    for f in files2copy:
-        srcf = os.path.join(src, f)
-        dstf = os.path.join(dst, f)
-
-        # Check to see if dstf is going into a subfolder, and create that
-        # subfolder if it doesn't exist
-        sf = os.path.dirname(dstf)
-        if not os.path.isdir(sf):
-            try:
-                os.mkdir(sf)
-            except:
-                print("Could not make " + sf)
-
-        # Now copy the file
-        if os.path.exists(srcf):
-            print("Copy file '" + srcf + "' -> '" + dstf + "'")
-            shutil.copy(srcf, dstf)
-        else:
-            print(srcf + " does not exist")
-
-    return mf6inp, mf6outp
+    for ext in extensions:
+        for file in workspace.glob(f"*.{ext}"):
+            yield file
 
 
 def get_mf6_comparison(src):
-    """Determine comparison type for MODFLOW 6 simulation.
+    """
+    Determine the comparison type for a MODFLOW 6 simulation
+    based on files present in the simulation workspace. Some
+    files take precedence over others according to the order
+    specified in `COMPARE_PROGRAMS`.
 
     Parameters
     ----------
@@ -440,210 +247,36 @@ def get_mf6_comparison(src):
         comparison type
 
     """
-    action = None
-    # Possible comparison - the order matters
-    optcomp = (
-        "compare",
-        ".cmp",
-        "mf2005",
-        "mf2005.cmp",
-        "mfnwt",
-        "mfnwt.cmp",
-        "mfusg",
-        "mfusg.cmp",
-        "mflgr",
-        "mflgr.cmp",
-        "libmf6",
-        "libmf6.cmp",
-        "mf6",
-        "mf6.cmp",
-    )
-    # Construct src pth from namefile
-    action = None
+
     for _, dirs, _ in os.walk(src):
         dl = [d.lower() for d in dirs]
-        for oc in optcomp:
-            if any(oc in s for s in dl):
-                action = oc
-                break
-    return action
+        for pattern in COMPARE_PROGRAMS:
+            if any(pattern in s for s in dl):
+                return pattern
 
 
-def setup_mf6_comparison(src, dst, remove_existing=True):
-    """Setup comparision for MODFLOW 6 simulation.
+def get_mf6_files(namefile, verbose=False):
+    """Get all MODFLOW 6 input and output files in this simulation.
 
     Parameters
     ----------
-    src : src
-        directory path with original MODFLOW 6 input files
-    dst : str
-        directory path that original MODFLOW 6 input files will be copied to
-    remove_existing : bool
-        boolean indicating if existing file in dst should be removed (default
-        is True)
-
-    Returns
-    -------
-    action : str
-        comparison type
-
-    """
-    # get the type of comparison to use (compare, mf2005, etc.)
-    action = get_mf6_comparison(src)
-
-    if action is not None:
-        dst = os.path.join(dst, f"{action}")
-        if not os.path.isdir(dst):
-            try:
-                os.mkdir(dst)
-            except:
-                print("Could not make " + dst)
-        # clean directory
-        else:
-            print(f"cleaning...{dst}")
-            for root, dirs, files in os.walk(dst):
-                for f in files:
-                    tpth = os.path.join(root, f)
-                    print(f"  removing...{tpth}")
-                    os.remove(tpth)
-                for d in dirs:
-                    tdir = os.path.join(root, d)
-                    print(f"  removing...{tdir}")
-                    shutil.rmtree(tdir)
-        # copy files
-        cmppth = os.path.join(src, action)
-        files = os.listdir(cmppth)
-        files2copy = []
-        if action.lower() == "compare" or action.lower() == ".cmp":
-            for file in files:
-                if ".cmp" in os.path.splitext(file)[1].lower():
-                    files2copy.append(os.path.join(cmppth, file))
-            for srcf in files2copy:
-                f = os.path.basename(srcf)
-                dstf = os.path.join(dst, f)
-                # Now copy the file
-                if os.path.exists(srcf):
-                    print("Copy file '" + srcf + "' -> '" + dstf + "'")
-                    shutil.copy(srcf, dstf)
-                else:
-                    print(srcf + " does not exist")
-        else:
-            if "mf6" in action.lower():
-                for file in files:
-                    if "mfsim.nam" in file.lower():
-                        srcf = os.path.join(cmppth, os.path.basename(file))
-                        files2copy.append(srcf)
-                        srcdir = os.path.join(src, action)
-                        setup_mf6(srcdir, dst, remove_existing=remove_existing)
-                        break
-            else:
-                for file in files:
-                    if ".nam" in os.path.splitext(file)[1].lower():
-                        srcf = os.path.join(cmppth, os.path.basename(file))
-                        files2copy.append(srcf)
-                        nf = os.path.join(src, action, os.path.basename(file))
-                        model_setup(nf, dst, remove_existing=remove_existing)
-                        break
-
-    return action
-
-
-def get_mf6_nper(tdisfile):
-    """Return the number of stress periods in the MODFLOW 6 model.
-
-    Parameters
-    ----------
-    tdisfile : str
-        path to the TDIS file
-
-    Returns
-    -------
-    nper : int
-        number of stress periods in the simulation
-
-    """
-    with open(tdisfile, "r") as f:
-        lines = f.readlines()
-    line = [line for line in lines if "NPER" in line.upper()][0]
-    nper = line.strip().split()[1]
-    return nper
-
-
-def get_mf6_mshape(disfile):
-    """Return the shape of the MODFLOW 6 model.
-
-    Parameters
-    ----------
-    disfile : str
-        path to a MODFLOW 6 discretization file
-
-    Returns
-    -------
-    mshape : tuple
-        tuple with the shape of the MODFLOW 6 model.
-
-    """
-    with open(disfile, "r") as f:
-        lines = f.readlines()
-
-    d = {}
-    for line in lines:
-
-        # Skip over blank and commented lines
-        ll = line.strip().split()
-        if len(ll) < 2:
-            continue
-        if line.strip()[0] in ["#", "!"]:
-            continue
-
-        for key in ["NODES", "NCPL", "NLAY", "NROW", "NCOL"]:
-            if ll[0].upper() in key:
-                d[key] = int(ll[1])
-
-    if "NODES" in d:
-        mshape = (d["NODES"],)
-    elif "NCPL" in d:
-        mshape = (d["NLAY"], d["NCPL"])
-    elif "NLAY" in d:
-        mshape = (d["NLAY"], d["NROW"], d["NCOL"])
-    else:
-        print(d)
-        raise Exception("Could not determine model shape")
-    return mshape
-
-
-def get_mf6_files(mfnamefile):
-    """Return a list of all the MODFLOW 6 input and output files in this model.
-
-    Parameters
-    ----------
-    mfnamefile : str
+    namefile : pathlike
         path to the MODFLOW 6 simulation name file
 
     Returns
     -------
-    filelist : list
-        list of MODFLOW 6 input files in a simulation
-    outplist : list
-        list of MODFLOW 6 output files in a simulation
-
+    A tuple of lists of paths (input files, output files)
     """
 
-    srcdir = os.path.dirname(mfnamefile)
-    filelist = []
-    outplist = []
-
-    filekeys = ["TDIS6", "GWF6", "GWT", "GWF6-GWF6", "GWF-GWT", "IMS6"]
-    namefilekeys = ["GWF6", "GWT"]
-    namefiles = []
-
-    with open(mfnamefile) as f:
-
-        # Read line and skip comments
-        lines = f.readlines()
-
-    for line in lines:
-
+    srcdir = os.path.dirname(namefile)
+    mdl_files = []
+    pkg_files = []
+    out_files = []
+    pkg_keys = ["TDIS6", "GWF6", "GWT6", "GWF6-GWF6", "GWF-GWT", "IMS6"]
+    model_keys = ["GWF6", "GWT"]
+
+    # find model and simulation-level package input files in simulation namefile
+    for line in open(namefile).readlines():
         # Skip over blank and commented lines
         ll = line.strip().split()
         if len(ll) < 2:
@@ -651,21 +284,20 @@ def get_mf6_files(mfnamefile):
         if line.strip()[0] in ["#", "!"]:
             continue
 
-        for key in filekeys:
+        for key in pkg_keys:
             if key in ll[0].upper():
                 fname = ll[1]
-                filelist.append(fname)
+                pkg_files.append(fname)
 
-        for key in namefilekeys:
+        for key in model_keys:
             if key in ll[0].upper():
                 fname = ll[1]
-                namefiles.append(fname)
+                mdl_files.append(fname)
 
-    # Go through name files and get files
-    for namefile in namefiles:
+    # find model-level package input files in model namefiles
+    for namefile in mdl_files:
         fname = os.path.join(srcdir, namefile)
-        with open(fname, "r") as f:
-            lines = f.readlines()
+        lines = open(fname, "r").readlines()
         insideblock = False
 
         for line in lines:
@@ -684,31 +316,34 @@ def get_mf6_files(mfnamefile):
                     continue
                 if line.strip()[0] in ["#", "!"]:
                     continue
-                filelist.append(ll[1])
+                pkg_files.append(ll[1])
 
-    # Recursively go through every file and look for other files to copy,
-    # such as 'OPEN/CLOSE' and 'TIMESERIESFILE'.  If found, then
-    # add that file to the list of files to copy.
-    flist = filelist
-    # olist = outplist
+    # Recurse through package input files and look for input or
+    # output file entries, e.g. 'OPEN/CLOSE',  'TIMESERIESFILE'
+    # or similar
+    flist = pkg_files
     while True:
         olist = []
-        flist, olist = _get_mf6_external_files(srcdir, olist, flist)
-        # add to filelist
-        if len(flist) > 0:
-            filelist = filelist + flist
-        # add to outplist
-        if len(olist) > 0:
-            outplist = outplist + olist
+        flist, olist = get_mf6_external_files(srcdir, olist, flist)
+        pkg_files += flist
+        out_files += olist
         # terminate loop if no additional files
         # if len(flist) < 1 and len(olist) < 1:
         if len(flist) < 1:
             break
 
-    return filelist, outplist
+    if verbose:
+        from pprint import pprint
+
+        print(f"Found input files for {namefile}:")
+        pprint(pkg_files)
+        print(f"Expecting output files for {namefile}:")
+        pprint(out_files)
+
+    return pkg_files, out_files
 
 
-def _get_mf6_external_files(srcdir, outplist, files):
+def get_mf6_external_files(srcdir, outplist, files):
     """Get list of external files in a MODFLOW 6 simulation.
 
     Parameters
@@ -731,7 +366,6 @@ def _get_mf6_external_files(srcdir, outplist, files):
         try:
             f = open(fname, "r")
             for line in f:
-
                 # Skip invalid lines
                 ll = line.strip().split()
                 if len(ll) < 2:
@@ -829,7 +463,6 @@ def get_mf6_ftypes(namefile, ftypekeys):
 
     ftypes = []
     for line in lines:
-
         # Skip over blank and commented lines
         ll = line.strip().split()
         if len(ll) < 2:
@@ -844,36 +477,264 @@ def get_mf6_ftypes(namefile, ftypekeys):
     return ftypes
 
 
-def get_mf6_blockdata(f, blockstr):
-    """Return list with all non comments between start and end of block
-    specified by blockstr.
+def get_regression_files(
+    workspace: os.PathLike, extensions
+) -> Tuple[List[str], List[str]]:
+    if isinstance(extensions, str):
+        extensions = [extensions]
+    files = os.listdir(workspace)
+    files0 = []
+    files1 = []
+    for file_name in files:
+        fpth0 = os.path.join(workspace, file_name)
+        if os.path.isfile(fpth0):
+            for extension in extensions:
+                if file_name.lower().endswith(extension):
+                    files0.append(fpth0)
+                    fpth1 = os.path.join(
+                        workspace, "mf6_regression", file_name
+                    )
+                    files1.append(fpth1)
+                    break
+    return files0, files1
+
+
+def setup_model(namefile, dst, remove_existing=True, extrafiles=None):
+    """
+    Setup a non-MF6 model test, copying input files to the destination workspace.
 
     Parameters
     ----------
-    f : file object
-        open file object
-    blockstr : str
-        name of block to search
+    namefile : str
+        MODFLOW-based model name file.
+    dst : str
+        destination path for comparison model or file(s)
+    remove_existing : bool
+        boolean indicating if an existing comparision model or file(s) should
+        be replaced (default is True)
+    extrafiles : str or list of str
+        list of extra files to include in the comparision
+
+    """
+    # Construct src pth from namefile or lgr file
+    src = os.path.dirname(namefile)
+
+    # Create the destination folder, if required
+    create_dir = False
+    if os.path.exists(dst):
+        if remove_existing:
+            print(f"Removing directory '{dst}'")
+            shutil.rmtree(dst)
+            create_dir = True
+    else:
+        create_dir = True
+    if create_dir:
+        os.mkdir(dst)
+
+    # determine if a namefile is a lgr control file - get individual
+    # name files out of the lgr control file
+    namefiles = [namefile]
+    ext = os.path.splitext(namefile)[1]
+    if ".lgr" in ext.lower():
+        lines = [line.rstrip("\n") for line in open(namefile)]
+        for line in lines:
+            if len(line) < 1:
+                continue
+            if line[0] == "#":
+                continue
+            t = line.split()
+            if ".nam" in t[0].lower():
+                fpth = os.path.join(src, t[0])
+                namefiles.append(fpth)
+
+    # Make list of files to copy
+    files2copy = []
+    for fpth in namefiles:
+        files2copy.append(os.path.basename(fpth))
+        ext = os.path.splitext(fpth)[1]
+        # copy additional files contained in the name file and
+        # associated package files
+        if ext.lower() == ".nam":
+            fname = os.path.abspath(fpth)
+            files2copy = files2copy + get_input_files(fname)
+
+    if extrafiles is not None:
+        if isinstance(extrafiles, str):
+            extrafiles = [extrafiles]
+        for fl in extrafiles:
+            files2copy.append(os.path.basename(fl))
+
+    # Copy the files
+    for f in files2copy:
+        srcf = os.path.join(src, f)
+        dstf = os.path.join(dst, f)
+
+        # Check to see if dstf is going into a subfolder, and create that
+        # subfolder if it doesn't exist
+        sf = os.path.dirname(dstf)
+        if not os.path.isdir(sf):
+            os.makedirs(sf)
+
+        # Now copy the file
+        if os.path.exists(srcf):
+            print(f"Copying file '{srcf}' -> '{dstf}'")
+            shutil.copy(srcf, dstf)
+        else:
+            print(f"{srcf} does not exist")
+
+
+def setup_mf6(
+    src, dst, mfnamefile="mfsim.nam", extrafiles=None, remove_existing=True
+):
+    """
+    Setup an MF6 simulation test, copying input files from the source
+    to the destination workspace.
+
+    Parameters
+    ----------
+    src : src
+        directory path with original MODFLOW 6 input files
+    dst : str
+        directory path that original MODFLOW 6 input files will be copied to
+    mfnamefile : str
+        optional MODFLOW 6 simulation name file (default is mfsim.nam)
+    extrafiles : bool
+        boolean indicating if extra files should be included (default is None)
+    remove_existing : bool
+        boolean indicating if existing file in dst should be removed (default
+        is True)
 
     Returns
     -------
-    data : list
-        list of data in specified block
+    mf6inp : list
+        list of MODFLOW 6 input files
+    mf6outp : list
+        list of MODFLOW 6 output files
 
     """
-    data = []
 
-    # find beginning of block
-    for line in f:
-        if line[0] != "#":
-            t = line.split()
-            if t[0].lower() == "begin" and t[1].lower() == blockstr.lower():
+    # Create the destination folder
+    create_dir = False
+    if os.path.exists(dst):
+        if remove_existing:
+            print(f"Removing {dst}")
+            shutil.rmtree(dst)
+            create_dir = True
+    else:
+        create_dir = True
+    if create_dir:
+        os.makedirs(dst)
+
+    # Make list of files to copy
+    fname = os.path.join(src, mfnamefile)
+    fname = os.path.abspath(fname)
+    mf6inp, mf6outp = get_mf6_files(fname)
+    files2copy = [mfnamefile] + mf6inp
+
+    # determine if there are any .ex files
+    exinp = []
+    for f in mf6outp:
+        ext = os.path.splitext(f)[1]
+        if ext.lower() == ".hds":
+            pth = os.path.join(src, f + ".ex")
+            if os.path.isfile(pth):
+                exinp.append(f + ".ex")
+    if len(exinp) > 0:
+        files2copy += exinp
+    if extrafiles is not None:
+        files2copy += extrafiles
+
+    # Copy the files
+    for f in files2copy:
+        srcf = os.path.join(src, f)
+        dstf = os.path.join(dst, f)
+
+        # Check to see if dstf is going into a subfolder, and create that
+        # subfolder if it doesn't exist
+        sf = os.path.dirname(dstf)
+        if not os.path.isdir(sf):
+            try:
+                os.mkdir(sf)
+            except:
+                print(f"Could not create directory '{sf}")
+
+        # Now copy the file
+        if os.path.exists(srcf):
+            print(f"Copying file '{srcf}' -> '{dstf}'")
+            shutil.copy(srcf, dstf)
+        else:
+            print(f"{srcf} does not exist")
+
+    return mf6inp, mf6outp
+
+
+def setup_mf6_comparison(
+    src, dst, cmp_exe="mf6", overwrite=True, verbose=False
+):
+    """Setup an output comparison for MODFLOW 6 simulation.
+
+    Parameters
+    ----------
+    src : path-like
+        Directory with original MODFLOW 6 input files.
+    dst : path-like
+        Directory to copy MODFLOW 6 input files to.
+    cmp_exe : str or PathLike, optional
+        Program to compare with, for supported see `COMPARE_PROGRAMSa.
+    overwrite : bool, optional
+        Whether to overwrite the destination directory if it exists (default is True).
+    verbose : bool, optional
+        Whether to show verbose output
+
+    Returns
+    -------
+    action : str
+        comparison type (also the name of the comparison subdirectory in dst)
+
+    """
+
+    if cmp_exe is None:
+        warn(f"No action provided, aborting")
+        return
+
+    # create and/or clean dest dir if needed
+    dst = Path(dst) / cmp_exe
+    dst.mkdir(exist_ok=True)
+    dls = list(os.walk(dst))
+    if overwrite and any(dls):
+        if verbose:
+            print(f"Cleaning directory '{dst}'")
+        for root, dirs, files in dls:
+            for f in files:
+                tpth = os.path.join(root, f)
+                if verbose:
+                    print("Removing file '{tpth}'")
+                os.remove(tpth)
+            for d in dirs:
+                tdir = os.path.join(root, d)
+                if verbose:
+                    print("Removing directory '{tdir}'")
+                shutil.rmtree(tdir)
+    else:
+        raise ValueError(f"Destination exists but overwrite disabled: {dst}")
+
+    # copy files
+    cmppth = os.path.join(src, cmp_exe)
+    files = os.listdir(cmppth)
+    files2copy = []
+    if "mf6" in cmp_exe.lower():
+        for file in files:
+            if "mfsim.nam" in file.lower():
+                srcf = os.path.join(cmppth, os.path.basename(file))
+                files2copy.append(srcf)
+                srcdir = os.path.join(src, cmp_exe)
+                setup_mf6(srcdir, dst, remove_existing=overwrite)
                 break
-    for line in f:
-        if line[0] != "#":
-            t = line.split()
-            if t[0].lower() == "end" and t[1].lower() == blockstr.lower():
+    else:
+        for file in files:
+            if ".nam" in os.path.splitext(file)[1].lower():
+                srcf = os.path.join(cmppth, os.path.basename(file))
+                files2copy.append(srcf)
+                nf = os.path.join(src, cmp_exe, os.path.basename(file))
+                setup_model(nf, dst, remove_existing=overwrite)
                 break
-            else:
-                data.append(line.rstrip())
-    return data
diff --git a/autotest/conftest.py b/autotest/conftest.py
index 5f0073b18c2..f278abff0bb 100644
--- a/autotest/conftest.py
+++ b/autotest/conftest.py
@@ -1,51 +1,93 @@
-import platform
+import sys
 from pathlib import Path
+from typing import Dict
+from warnings import warn
 
 import pytest
-from modflow_devtools.executables import Executables, build_default_exe_dict
+from modflow_devtools.ostags import get_binary_suffixes
 
 pytest_plugins = ["modflow_devtools.fixtures"]
 project_root_path = Path(__file__).resolve().parent.parent
 
 
-def should_compare(
-    test: str, comparisons: dict, executables: Executables
-) -> bool:
-    if test in comparisons.keys():
-        dev_ver = Executables.get_version(path=executables.mf6).split(" ")[0]
-        reg_ver = Executables.get_version(
-            path=executables.mf6_regression
-        ).split(" ")[0]
-        print(f"MODFLOW 6 development version: {dev_ver}")
-        print(f"MODFLOW 6 regression version: {reg_ver}")
-        excluded = list(comparisons[test])
-        if reg_ver in excluded:
-            print(
-                f"Regression version {reg_ver} not supported for test {test}, skipping comparison"
-            )
-            return False
-    return True
+_exe_ext, _lib_ext = get_binary_suffixes(sys.platform)
+_binaries_path = project_root_path / "bin"
+_dl_bin_path = _binaries_path / "downloaded"
+_rb_bin_path = _binaries_path / "rebuilt"
+_binaries = {
+    "development": [
+        ("mf6", _binaries_path / f"mf6{_exe_ext}"),
+        ("libmf6", _binaries_path / f"libmf6{_lib_ext}"),
+        ("mf5to6", _binaries_path / f"mf5to6{_exe_ext}"),
+        ("zbud6", _binaries_path / f"zbud6{_exe_ext}"),
+    ],
+    "downloaded": [
+        ("mf2000", _dl_bin_path / f"mf2000{_exe_ext}"),
+        ("mf2005", _dl_bin_path / f"mf2005dbl{_exe_ext}"),
+        ("mfnwt", _dl_bin_path / f"mfnwtdbl{_exe_ext}"),
+        ("mfusg", _dl_bin_path / f"mfusgdbl{_exe_ext}"),
+        ("mflgr", _dl_bin_path / f"mflgrdbl{_exe_ext}"),
+        ("mf2005s", _dl_bin_path / f"mf2005{_exe_ext}"),
+        ("mt3dms", _dl_bin_path / f"mt3dms{_exe_ext}"),
+        ("crt", _dl_bin_path / f"crt{_exe_ext}"),
+        ("gridgen", _dl_bin_path / f"gridgen{_exe_ext}"),
+        ("mp6", _dl_bin_path / f"mp6{_exe_ext}"),
+        ("mp7", _dl_bin_path / f"mp7{_exe_ext}"),
+        ("swtv4", _dl_bin_path / f"swtv4{_exe_ext}"),
+        ("sutra", _dl_bin_path / f"sutra{_exe_ext}"),
+        ("triangle", _dl_bin_path / f"triangle{_exe_ext}"),
+        ("vs2dt", _dl_bin_path / f"vs2dt{_exe_ext}"),
+        ("zonbudusg", _dl_bin_path / f"zonbudusg{_exe_ext}"),
+    ],
+    "rebuilt": [
+        ("mf6_regression", _rb_bin_path / f"mf6{_exe_ext}"),
+        ("libmf6_regression", _rb_bin_path / f"libmf6{_lib_ext}"),
+        ("mf5to6_regression", _rb_bin_path / f"mf5to6{_exe_ext}"),
+        ("zbud6_regression", _rb_bin_path / f"zbud6{_exe_ext}"),
+    ],
+}
 
 
 @pytest.fixture(scope="session")
 def bin_path() -> Path:
-    return project_root_path / "bin"
+    return _binaries_path
 
 
 @pytest.fixture(scope="session")
-def libmf6_path(bin_path) -> Path:
-    ext = {
-        "Darwin": ".dylib",
-        "Linux": ".so",
-        "Windows": ".dll",
-    }[platform.system()]
-    lib_name = bin_path / f"libmf6{ext}"
-    return lib_name
-
-
-@pytest.fixture(scope="session")
-def targets(bin_path) -> Executables:
-    return Executables(**build_default_exe_dict(bin_path))
+def targets() -> Dict[str, Path]:
+    """
+    Target executables for tests. These include local development builds as
+    well as binaries 1) downloaded from GitHub and 2) rebuilt from the last
+    official release.
+    """
+
+    d = dict()
+    for k, v in _binaries["development"]:
+        # require development binaries
+        assert v.is_file(), f"Couldn't find binary '{k}' expected at: {v}"
+        d[k] = v
+    for k, v in _binaries["downloaded"] + _binaries["rebuilt"]:
+        # downloaded/rebuilt binaries are optional
+        if v.is_file():
+            d[k] = v
+        else:
+            warn(f"Couldn't find binary '{k}' expected at: {v}")
+    return d
+
+
+def try_get_target(targets: Dict[str, Path], name: str) -> Path:
+    """Try to retrieve the path to a binary. If the binary is a development
+    target and can't be found, an error is raised. Otherwise (if the binary
+    is downloaded or rebuilt) the test is skipped. This is to allow testing
+    without downloaded or rebuilt binaries, e.g. if the network is down."""
+
+    exe = targets.get(name)
+    if exe:
+        return exe
+    elif name in _binaries["development"]:
+        raise ValueError(f"Couldn't find binary '{name}'")
+    else:
+        pytest.skip(f"Couldn't find binary '{name}'")
 
 
 @pytest.fixture
@@ -55,7 +97,7 @@ def original_regression(request) -> bool:
 
 @pytest.fixture(scope="session")
 def markers(pytestconfig) -> str:
-    return pytestconfig.getoption('-m')
+    return pytestconfig.getoption("-m")
 
 
 def pytest_addoption(parser):
@@ -63,13 +105,13 @@ def pytest_addoption(parser):
         "--original-regression",
         action="store_true",
         default=False,
-        help="TODO",
+        help="use non-MF6 models for regression tests",
     )
     parser.addoption(
-        "--parallel", 
-        action="store_true", 
-        default=False, 
-        help="include parallel test cases"
+        "--parallel",
+        action="store_true",
+        default=False,
+        help="include parallel test cases",
     )
 
 
diff --git a/autotest/cross_section_functions.py b/autotest/cross_section_functions.py
index 1b22e137e0d..9bfda231dcd 100644
--- a/autotest/cross_section_functions.py
+++ b/autotest/cross_section_functions.py
@@ -12,7 +12,7 @@ def calculate_rectchan_mannings_discharge(
 
     """
     area = width * depth
-    return conversion_factor * area * depth ** mpow * slope ** 0.5 / roughness
+    return conversion_factor * area * depth**mpow * slope**0.5 / roughness
 
 
 # n-point cross-section functions
@@ -82,7 +82,7 @@ def get_wetted_perimeter(
         else:
             dlen = 0.0
 
-    return np.sqrt(xlen ** 2.0 + dlen ** 2.0)
+    return np.sqrt(xlen**2.0 + dlen**2.0)
 
 
 def get_wetted_area(x0, x1, h0, h1, depth):
@@ -257,7 +257,7 @@ def manningsq(
             if perimeter > 0.0:
                 radius = area / perimeter
                 q += (
-                    conv * area * radius ** mpow * slope ** 0.5 / roughness[i0]
+                    conv * area * radius**mpow * slope**0.5 / roughness[i0]
                 )
     else:
         perimeter = wetted_perimeter(x, h, depth)
@@ -265,7 +265,7 @@ def manningsq(
         radius = 0.0
         if perimeter > 0.0:
             radius = area / perimeter
-        q = conv * area * radius ** mpow * slope ** 0.5 / roughness[0]
+        q = conv * area * radius**mpow * slope**0.5 / roughness[0]
     return q
 
 
diff --git a/autotest/data/ex-gwf-bump/bottom.txt b/autotest/data/ex-gwf-bump/bottom.txt
new file mode 100644
index 00000000000..fc7264d51e2
--- /dev/null
+++ b/autotest/data/ex-gwf-bump/bottom.txt
@@ -0,0 +1,52 @@
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   1.924449E-03   7.145278E-02   1.258685E-01   1.649210E-01   1.884270E-01   1.962749E-01   1.884270E-01   1.649210E-01   1.258685E-01   7.145278E-02   1.924449E-03   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   7.920820E-02   1.962749E-01   2.988742E-01   3.865433E-01   4.588710E-01   5.155069E-01   5.561688E-01   5.806502E-01   5.888247E-01   5.806502E-01   5.561688E-01   5.155069E-01   4.588710E-01   3.865433E-01   2.988742E-01   1.962749E-01   7.920820E-02   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   1.924449E-03   1.649210E-01   3.147551E-01   4.508076E-01   5.724826E-01   6.792177E-01   7.704949E-01   8.458526E-01   9.048952E-01   9.473040E-01   9.728448E-01   9.813745E-01   9.728448E-01   9.473040E-01   9.048952E-01   8.458526E-01   7.704949E-01   6.792177E-01   5.724826E-01   4.508076E-01   3.147551E-01   1.649210E-01   1.924449E-03   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   1.727501E-01   3.545715E-01   5.236254E-01   6.792177E-01   8.206647E-01   9.473040E-01   1.058507E+00   1.153693E+00   1.232340E+00   1.294000E+00   1.338311E+00   1.365007E+00   1.373924E+00   1.365007E+00   1.338311E+00   1.294000E+00   1.232340E+00   1.153693E+00   1.058507E+00   9.473040E-01   8.206647E-01   6.792177E-01   5.236254E-01   3.545715E-01   1.727501E-01   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   1.025109E-01   3.147551E-01   5.155069E-01   7.040227E-01   8.795444E-01   1.041309E+00   1.188560E+00   1.320560E+00   1.436603E+00   1.536034E+00   1.618264E+00   1.682781E+00   1.729173E+00   1.757133E+00   1.766474E+00   1.757133E+00   1.729173E+00   1.682781E+00   1.618264E+00   1.536034E+00   1.436603E+00   1.320560E+00   1.188560E+00   1.041309E+00   8.795444E-01   7.040227E-01   5.155069E-01   3.147551E-01   1.025109E-01   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   1.962749E-01   4.266580E-01   6.462466E-01   8.542639E-01   1.049904E+00   1.232340E+00   1.400731E+00   1.554238E+00   1.692039E+00   1.813339E+00   1.917398E+00   2.003544E+00   2.071192E+00   2.119867E+00   2.149216E+00   2.159024E+00   2.149216E+00   2.119867E+00   2.071192E+00   2.003544E+00   1.917398E+00   1.813339E+00   1.692039E+00   1.554238E+00   1.400731E+00   1.232340E+00   1.049904E+00   8.542639E-01   6.462466E-01   4.266580E-01   1.962749E-01   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   1.924449E-03   2.592852E-01   5.073954E-01   7.455119E-01   9.728448E-01   1.188560E+00   1.391786E+00   1.581618E+00   1.757133E+00   1.917398E+00   2.061492E+00   2.188521E+00   2.297640E+00   2.388082E+00   2.459174E+00   2.510366E+00   2.541251E+00   2.551574E+00   2.541251E+00   2.510366E+00   2.459174E+00   2.388082E+00   2.297640E+00   2.188521E+00   2.061492E+00   1.917398E+00   1.757133E+00   1.581618E+00   1.391786E+00   1.188560E+00   9.728448E-01   7.455119E-01   5.073954E-01   2.592852E-01   1.924449E-03   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   1.733338E-02   2.909435E-01   5.561688E-01   8.122841E-01   1.058507E+00   1.294000E+00   1.517869E+00   1.729173E+00   1.926925E+00   2.110108E+00   2.277686E+00   2.428624E+00   2.561911E+00   2.676584E+00   2.771759E+00   2.846658E+00   2.900641E+00   2.933228E+00   2.944124E+00   2.933228E+00   2.900641E+00   2.846658E+00   2.771759E+00   2.676584E+00   2.561911E+00   2.428624E+00   2.277686E+00   2.110108E+00   1.926925E+00   1.729173E+00   1.517869E+00   1.294000E+00   1.058507E+00   8.122841E-01   5.561688E-01   2.909435E-01   1.733338E-02   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   1.924449E-03   2.909435E-01   5.724826E-01   8.458526E-01   1.110300E+00   1.365007E+00   1.609087E+00   1.841588E+00   2.061492E+00   2.267728E+00   2.459174E+00   2.634679E+00   2.793080E+00   2.933228E+00   3.054020E+00   3.154432E+00   3.233560E+00   3.290650E+00   3.325138E+00   3.336673E+00   3.325138E+00   3.290650E+00   3.233560E+00   3.154432E+00   3.054020E+00   2.933228E+00   2.793080E+00   2.634679E+00   2.459174E+00   2.267728E+00   2.061492E+00   1.841588E+00   1.609087E+00   1.365007E+00   1.110300E+00   8.458526E-01   5.724826E-01   2.909435E-01   1.924449E-03   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   2.592852E-01   5.561688E-01   8.458526E-01   1.127632E+00   1.400731E+00   1.664297E+00   1.917398E+00   2.159024E+00   2.388082E+00   2.603405E+00   2.803764E+00   2.987876E+00   3.154432E+00   3.302126E+00   3.429686E+00   3.535923E+00   3.619772E+00   3.680345E+00   3.716968E+00   3.729223E+00   3.716968E+00   3.680345E+00   3.619772E+00   3.535923E+00   3.429686E+00   3.302126E+00   3.154432E+00   2.987876E+00   2.803764E+00   2.603405E+00   2.388082E+00   2.159024E+00   1.917398E+00   1.664297E+00   1.400731E+00   1.127632E+00   8.458526E-01   5.561688E-01   2.592852E-01   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
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+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   1.924449E-03   2.909435E-01   5.724826E-01   8.458526E-01   1.110300E+00   1.365007E+00   1.609087E+00   1.841588E+00   2.061492E+00   2.267728E+00   2.459174E+00   2.634679E+00   2.793080E+00   2.933228E+00   3.054020E+00   3.154432E+00   3.233560E+00   3.290650E+00   3.325138E+00   3.336673E+00   3.325138E+00   3.290650E+00   3.233560E+00   3.154432E+00   3.054020E+00   2.933228E+00   2.793080E+00   2.634679E+00   2.459174E+00   2.267728E+00   2.061492E+00   1.841588E+00   1.609087E+00   1.365007E+00   1.110300E+00   8.458526E-01   5.724826E-01   2.909435E-01   1.924449E-03   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   1.733338E-02   2.909435E-01   5.561688E-01   8.122841E-01   1.058507E+00   1.294000E+00   1.517869E+00   1.729173E+00   1.926925E+00   2.110108E+00   2.277686E+00   2.428624E+00   2.561911E+00   2.676584E+00   2.771759E+00   2.846658E+00   2.900641E+00   2.933228E+00   2.944124E+00   2.933228E+00   2.900641E+00   2.846658E+00   2.771759E+00   2.676584E+00   2.561911E+00   2.428624E+00   2.277686E+00   2.110108E+00   1.926925E+00   1.729173E+00   1.517869E+00   1.294000E+00   1.058507E+00   8.122841E-01   5.561688E-01   2.909435E-01   1.733338E-02   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   1.924449E-03   2.592852E-01   5.073954E-01   7.455119E-01   9.728448E-01   1.188560E+00   1.391786E+00   1.581618E+00   1.757133E+00   1.917398E+00   2.061492E+00   2.188521E+00   2.297640E+00   2.388082E+00   2.459174E+00   2.510366E+00   2.541251E+00   2.551574E+00   2.541251E+00   2.510366E+00   2.459174E+00   2.388082E+00   2.297640E+00   2.188521E+00   2.061492E+00   1.917398E+00   1.757133E+00   1.581618E+00   1.391786E+00   1.188560E+00   9.728448E-01   7.455119E-01   5.073954E-01   2.592852E-01   1.924449E-03   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   1.962749E-01   4.266580E-01   6.462466E-01   8.542639E-01   1.049904E+00   1.232340E+00   1.400731E+00   1.554238E+00   1.692039E+00   1.813339E+00   1.917398E+00   2.003544E+00   2.071192E+00   2.119867E+00   2.149216E+00   2.159024E+00   2.149216E+00   2.119867E+00   2.071192E+00   2.003544E+00   1.917398E+00   1.813339E+00   1.692039E+00   1.554238E+00   1.400731E+00   1.232340E+00   1.049904E+00   8.542639E-01   6.462466E-01   4.266580E-01   1.962749E-01   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   1.025109E-01   3.147551E-01   5.155069E-01   7.040227E-01   8.795444E-01   1.041309E+00   1.188560E+00   1.320560E+00   1.436603E+00   1.536034E+00   1.618264E+00   1.682781E+00   1.729173E+00   1.757133E+00   1.766474E+00   1.757133E+00   1.729173E+00   1.682781E+00   1.618264E+00   1.536034E+00   1.436603E+00   1.320560E+00   1.188560E+00   1.041309E+00   8.795444E-01   7.040227E-01   5.155069E-01   3.147551E-01   1.025109E-01   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   1.727501E-01   3.545715E-01   5.236254E-01   6.792177E-01   8.206647E-01   9.473040E-01   1.058507E+00   1.153693E+00   1.232340E+00   1.294000E+00   1.338311E+00   1.365007E+00   1.373924E+00   1.365007E+00   1.338311E+00   1.294000E+00   1.232340E+00   1.153693E+00   1.058507E+00   9.473040E-01   8.206647E-01   6.792177E-01   5.236254E-01   3.545715E-01   1.727501E-01   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   1.924449E-03   1.649210E-01   3.147551E-01   4.508076E-01   5.724826E-01   6.792177E-01   7.704949E-01   8.458526E-01   9.048952E-01   9.473040E-01   9.728448E-01   9.813745E-01   9.728448E-01   9.473040E-01   9.048952E-01   8.458526E-01   7.704949E-01   6.792177E-01   5.724826E-01   4.508076E-01   3.147551E-01   1.649210E-01   1.924449E-03   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   7.920820E-02   1.962749E-01   2.988742E-01   3.865433E-01   4.588710E-01   5.155069E-01   5.561688E-01   5.806502E-01   5.888247E-01   5.806502E-01   5.561688E-01   5.155069E-01   4.588710E-01   3.865433E-01   2.988742E-01   1.962749E-01   7.920820E-02   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   1.924449E-03   7.145278E-02   1.258685E-01   1.649210E-01   1.884270E-01   1.962749E-01   1.884270E-01   1.649210E-01   1.258685E-01   7.145278E-02   1.924449E-03   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00   0.000000E+00
+
diff --git a/autotest/data/ex-gwf-bump/results.hds.cmp b/autotest/data/ex-gwf-bump/results.hds.cmp
new file mode 100644
index 00000000000..ec8e622f7ba
Binary files /dev/null and b/autotest/data/ex-gwf-bump/results.hds.cmp differ
diff --git a/autotest/data/prudic2004test2/sfr-packagedata.dat b/autotest/data/prudic2004test2/sfr-packagedata.dat
index 7c6623704c5..ca8dff8916a 100644
--- a/autotest/data/prudic2004test2/sfr-packagedata.dat
+++ b/autotest/data/prudic2004test2/sfr-packagedata.dat
@@ -1,39 +1,39 @@
-#rno rlen rwid rgrd rtp rbth rhk man ncon ustrf ndv
-   0 400.0000 5.000000 0.1818182E-02 48.63636 1.000000 100.0000 0.3000000E-01    1 1.0000   0
-   1 200.0000 5.000000 0.1818182E-02 48.09091 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-   2 400.0000 5.000000 0.1818182E-02 47.54546 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-   3 400.0000 5.000000 0.1818182E-02 46.81818 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-   4 400.0000 5.000000 0.1818182E-02 46.09091 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-   5 400.0000 5.000000 0.1818182E-02 45.36364 1.000000 100.0000 0.3000000E-01    1 1.0000   0
-   6 400.0000 5.000000 0.2187500E-02 44.06250 1.000000 100.0000 0.3000000E-01    1 1.0000   0
-   7 400.0000 5.000000 0.2187500E-02 43.18750 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-   8 400.0000 5.000000 0.2187500E-02 42.31250 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-   9 400.0000 5.000000 0.2187500E-02 41.43750 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  10 400.0000 5.000000 0.2187500E-02 40.56250 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  11 400.0000 5.000000 0.2187500E-02 39.68750 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  12 400.0000 5.000000 0.2187500E-02 38.81250 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  13 400.0000 5.000000 0.2187500E-02 37.93750 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  14 400.0000 5.000000 0.2187500E-02 37.06250 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  15 400.0000 5.000000 0.2187500E-02 36.18750 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  16 400.0000 5.000000 0.2187500E-02 35.31250 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  17 400.0000 5.000000 0.2187500E-02 34.43750 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  18 400.0000 5.000000 0.1704545E-02 41.15909 1.000000 100.0000 0.3000000E-01    1 1.0000   0
-  19 200.0000 5.000000 0.1704545E-02 40.64773 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  20 200.0000 5.000000 0.1704545E-02 40.30682 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  21 400.0000 5.000000 0.1704545E-02 39.79546 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  22 400.0000 5.000000 0.1704545E-02 39.11364 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  23 400.0000 5.000000 0.1704545E-02 38.43182 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  24 400.0000 5.000000 0.1704545E-02 37.75000 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  25 200.0000 5.000000 0.1704545E-02 37.23864 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  26 200.0000 5.000000 0.1704545E-02 36.89773 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  27 400.0000 5.000000 0.1704545E-02 36.38636 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  28 400.0000 5.000000 0.1704545E-02 35.70454 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  29 400.0000 5.000000 0.1704545E-02 35.02273 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  30 400.0000 5.000000 0.1704545E-02 34.34091 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  31 400.0000 5.000000 0.2428571E-02 33.51429 1.000000 100.0000 0.3000000E-01    3 1.0000   0
-  32 400.0000 5.000000 0.2428571E-02 32.54286 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  33 400.0000 5.000000 0.2428571E-02 31.57143 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  34 400.0000 5.000000 0.2428571E-02 30.60000 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  35 400.0000 5.000000 0.2428571E-02 29.62857 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  36 400.0000 5.000000 0.2428571E-02 28.65714 1.000000 100.0000 0.3000000E-01    2 1.0000   0
-  37 400.0000 5.000000 0.2428571E-02 27.68571 1.000000 100.0000 0.3000000E-01    1 1.0000   0
+#ifno rlen rwid rgrd rtp rbth rhk man ncon ustrf ndv
+    0 400.0000 5.000000 0.1818182E-02 48.63636 1.000000 100.0000 0.3000000E-01    1 1.0000   0
+    1 200.0000 5.000000 0.1818182E-02 48.09091 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+    2 400.0000 5.000000 0.1818182E-02 47.54546 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+    3 400.0000 5.000000 0.1818182E-02 46.81818 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+    4 400.0000 5.000000 0.1818182E-02 46.09091 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+    5 400.0000 5.000000 0.1818182E-02 45.36364 1.000000 100.0000 0.3000000E-01    1 1.0000   0
+    6 400.0000 5.000000 0.2187500E-02 44.06250 1.000000 100.0000 0.3000000E-01    1 1.0000   0
+    7 400.0000 5.000000 0.2187500E-02 43.18750 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+    8 400.0000 5.000000 0.2187500E-02 42.31250 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+    9 400.0000 5.000000 0.2187500E-02 41.43750 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   10 400.0000 5.000000 0.2187500E-02 40.56250 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   11 400.0000 5.000000 0.2187500E-02 39.68750 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   12 400.0000 5.000000 0.2187500E-02 38.81250 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   13 400.0000 5.000000 0.2187500E-02 37.93750 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   14 400.0000 5.000000 0.2187500E-02 37.06250 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   15 400.0000 5.000000 0.2187500E-02 36.18750 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   16 400.0000 5.000000 0.2187500E-02 35.31250 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   17 400.0000 5.000000 0.2187500E-02 34.43750 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   18 400.0000 5.000000 0.1704545E-02 41.15909 1.000000 100.0000 0.3000000E-01    1 1.0000   0
+   19 200.0000 5.000000 0.1704545E-02 40.64773 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   20 200.0000 5.000000 0.1704545E-02 40.30682 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   21 400.0000 5.000000 0.1704545E-02 39.79546 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   22 400.0000 5.000000 0.1704545E-02 39.11364 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   23 400.0000 5.000000 0.1704545E-02 38.43182 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   24 400.0000 5.000000 0.1704545E-02 37.75000 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   25 200.0000 5.000000 0.1704545E-02 37.23864 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   26 200.0000 5.000000 0.1704545E-02 36.89773 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   27 400.0000 5.000000 0.1704545E-02 36.38636 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   28 400.0000 5.000000 0.1704545E-02 35.70454 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   29 400.0000 5.000000 0.1704545E-02 35.02273 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   30 400.0000 5.000000 0.1704545E-02 34.34091 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   31 400.0000 5.000000 0.2428571E-02 33.51429 1.000000 100.0000 0.3000000E-01    3 1.0000   0
+   32 400.0000 5.000000 0.2428571E-02 32.54286 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   33 400.0000 5.000000 0.2428571E-02 31.57143 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   34 400.0000 5.000000 0.2428571E-02 30.60000 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   35 400.0000 5.000000 0.2428571E-02 29.62857 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   36 400.0000 5.000000 0.2428571E-02 28.65714 1.000000 100.0000 0.3000000E-01    2 1.0000   0
+   37 400.0000 5.000000 0.2428571E-02 27.68571 1.000000 100.0000 0.3000000E-01    1 1.0000   0
diff --git a/autotest/framework.py b/autotest/framework.py
index 6e4e89c0832..8bfd0855169 100644
--- a/autotest/framework.py
+++ b/autotest/framework.py
@@ -1,53 +1,798 @@
+import os
+import shutil
+import time
+from itertools import repeat
+from pathlib import Path
+from subprocess import PIPE, STDOUT, Popen
+from traceback import format_exc
+from typing import Callable, Dict, Iterable, List, Optional, Tuple, Union
+from warnings import warn
+
 import flopy
+import numpy as np
+from common_regression import (
+    COMPARE_PROGRAMS,
+    adjust_htol,
+    get_mf6_comparison,
+    get_mf6_files,
+    get_namefiles,
+    get_rclose,
+    get_regression_files,
+    setup_mf6,
+    setup_mf6_comparison,
+)
+from flopy.mbase import BaseModel
+from flopy.mf6 import MFSimulation
+from flopy.utils.compare import compare_heads
+from modflow_devtools.misc import get_ostag, is_in_ci
+
+DNODATA = 3.0e30
+EXTTEXT = {
+    "hds": "head",
+    "hed": "head",
+    "bhd": "head",
+    "ucn": "concentration",
+    "cbc": "cell-by-cell",
+}
+HDS_EXT = (
+    "hds",
+    "hed",
+    "bhd",
+    "ahd",
+    "bin",
+)
+CBC_EXT = (
+    "cbc",
+    "bud",
+)
+
+
+def api_return(success, model_ws) -> Tuple[bool, List[str]]:
+    """
+    parse libmf6 stdout shared object file
+    """
+    fpth = os.path.join(model_ws, "mfsim.stdout")
+    return success, open(fpth).readlines()
+
+
+def get_mfsim_lst_tail(path: os.PathLike, lines=100) -> str:
+    """Get the tail of the mfsim.lst listing file"""
+    msg = ""
+    _lines = open(path).read().splitlines()
+    msg = "\n" + 79 * "-" + "\n"
+    i0 = -lines if len(_lines) > lines else 0
+    for line in _lines[i0:]:
+        if len(line) > 0:
+            msg += f"{line}\n"
+    msg += 79 * "-" + "\n\n"
+    return msg
+
+
+def get_workspace(sim_or_model) -> Path:
+    if isinstance(sim_or_model, MFSimulation):
+        return sim_or_model.sim_path
+    elif isinstance(sim_or_model, BaseModel):
+        return Path(sim_or_model.model_ws)
+    else:
+        raise ValueError(f"Unsupported model type: {type(sim_or_model)}")
+
+
+def run_parallel(workspace, target, ncpus) -> Tuple[bool, List[str]]:
+    if not is_in_ci() and get_ostag() in ["mac"]:
+        oversubscribed = ["--hostfile", "localhost"]
+        with open(f"{workspace}/localhost", "w") as f:
+            f.write(f"localhost slots={ncpus}\n")
+    else:
+        oversubscribed = ["--oversubscribe"]
+
+    normal_msg = "normal termination"
+    success = False
+    nr_success = 0
+    buff = []
+
+    # parallel commands
+    mpiexec_cmd = (
+        ["mpiexec"] + oversubscribed + ["-np", str(ncpus), target, "-p"]
+    )
+
+    proc = Popen(mpiexec_cmd, stdout=PIPE, stderr=STDOUT, cwd=workspace)
+
+    while True:
+        line = proc.stdout.readline().decode("utf-8")
+        if line == "" and proc.poll() is not None:
+            break
+        if line:
+            # success is when the success message appears
+            # in every process of the parallel simulation
+            if normal_msg in line.lower():
+                nr_success += 1
+                if nr_success == ncpus:
+                    success = True
+            line = line.rstrip("\r\n")
+            print(line)
+            buff.append(line)
+        else:
+            break
+
+    return success, buff
+
+
+def write_input(*sims, overwrite: bool = True, verbose: bool = True):
+    """
+    Write input files for `flopy.mf6.MFSimulation` or `flopy.mbase.BaseModel`.
+
+    Parameters
+    ----------
+
+    sims : arbitrary list
+        Simulations or models
+    verbose : bool, optional
+        whether to show verbose output
+    """
+
+    if sims is None:
+        warn("No simulations or models!")
+        return
+
+    # write input files for each model or simulation
+    for sim in sims:
+        if sim is None:
+            continue
+
+        if isinstance(sim, flopy.mf6.MFSimulation):
+            workspace = Path(sim.sim_path)
+            if any(workspace.glob("*")) and not overwrite:
+                warn(f"Workspace is not empty, not writing input files")
+                return
+            if verbose:
+                print(
+                    f"Writing mf6 simulation '{sim.name}' to: {sim.sim_path}"
+                )
+            sim.write_simulation()
+        elif isinstance(sim, flopy.mbase.BaseModel):
+            workspace = Path(sim.model_ws)
+            if any(workspace.glob("*")) and not overwrite:
+                warn(f"Workspace is not empty, not writing input files")
+                return
+            if verbose:
+                print(
+                    f"Writing {type(sim)} model '{sim.name}' to: {sim.model_ws}"
+                )
+            sim.write_input()
+        else:
+            raise ValueError(f"Unsupported simulation/model type: {type(sim)}")
 
 
 class TestFramework:
-    # tell pytest this isn't a test class, don't collect it
+    """
+    Defines a MODFLOW 6 test and its lifecycle, with configurable
+    hooks to evaluate results or run other models for comparison:
+
+        - MODFLOW 6 (directly or via API)
+        - MODFLOW-2005
+        - MODFLOW-NWT
+        - MODFLOW-USG
+        - MODFLOW-LGR
+
+    Parameters
+    ----------
+    name : str
+        The test name
+    workspace : pathlike
+        The test workspace
+    targets : dict
+        Binary targets to test against. Development binaries are
+        required, downloads/rebuilt binaries are optional (if not
+        found, comparisons and regression tests will be skipped).
+        Dictionary maps target names to paths. The test framework
+        will refuse to run a program if it is not a known target.
+    build : function, optional
+        User defined function returning one or more simulations/models.
+        Takes `self` as input. This is the place to build simulations.
+        If no build function is provided, input files must be written
+        to the test `workspace` prior to calling `run()`.
+    check : function, optional
+        User defined function to evaluate results of the simulation.
+        Takes `self` as input. This is a good place for assertions.
+    parallel : bool, optional
+        Whether to test mf6 parallel capabilities.
+    ncpus : int, optional
+        Number of CPUs for mf6 parallel testing.
+    htol : float, optional
+        Tolerance for result comparisons.
+    rclose : float, optional
+        Residual tolerance for convergence
+    verbose: bool, optional
+        Whether to show verbose output
+    xfail : bool, optional
+        Whether the test is expected to fail
+    api_func: function, optional
+        User defined function invoking the MODFLOW API, accepting
+        the MF6 library path and the test workspace as parameters
+    compare: str, optional
+        String selecting the comparison executable. Must be a key
+        into the `targets` dictionary, i.e. the name of a program
+        to use for the comparison model. Acceptable values: auto,
+        mf6, mf6_regression, libmf6, mf2005, mfnwt, mflgr, mfnwt.
+        If 'auto', the program to use is determined automatically
+        by contents of the comparison model/simulation workspace.
+    """
+
+    # tell pytest this class doesn't contain tests, don't collect it
     __test__ = False
 
-    def build(self, build_function, idx, exdir):
+    def __init__(
+        self,
+        name: str,
+        workspace: Union[str, os.PathLike],
+        targets: Dict[str, Path],
+        api_func: Optional[Callable] = None,
+        build: Optional[Callable] = None,
+        check: Optional[Callable] = None,
+        compare: Optional[str] = "auto",
+        parallel=False,
+        ncpus=1,
+        htol=None,
+        rclose=None,
+        overwrite=True,
+        verbose=False,
+        xfail=False,
+    ):
+        # make sure workspace exists
+        workspace = Path(workspace).expanduser().absolute()
+        assert workspace.is_dir(), f"{workspace} is not a valid directory"
+        if verbose:
+            print("Initializing test", name, "in workspace", workspace)
+
+        self.name = name
+        self.workspace = workspace
+        self.targets = targets
+        self.build = build
+        self.check = check
+        self.parallel = parallel
+        self.ncpus = [ncpus] if isinstance(ncpus, int) else ncpus
+        self.api_func = api_func
+        self.compare = compare
+        self.outp = None
+        self.htol = 0.001 if htol is None else htol
+        self.rclose = 0.001 if rclose is None else rclose
+        self.overwrite = overwrite
+        self.verbose = verbose
+        self.xfail = [xfail] if isinstance(xfail, bool) else xfail
+
+    def __repr__(self):
+        return self.name
+
+    # private
+
+    def _compare_heads(
+        self, cpth=None, extensions="hds", mf6=False, htol=0.001
+    ) -> bool:
+        if isinstance(extensions, str):
+            extensions = [extensions]
+
+        if cpth:
+            files1 = []
+            files2 = []
+            exfiles = []
+            for file1 in self.outp:
+                ext = os.path.splitext(file1)[1][1:]
+                if ext.lower() in extensions:
+                    # simulation file
+                    pth = os.path.join(self.workspace, file1)
+                    files1.append(pth)
+
+                    # look for an exclusion file
+                    pth = os.path.join(self.workspace, file1 + ".ex")
+                    exfiles.append(pth if os.path.isfile(pth) else None)
+
+                    # look for a comparison file
+                    coutp = None
+                    if mf6:
+                        _, coutp = get_mf6_files(cpth / "mfsim.nam")
+                    if coutp is not None:
+                        for file2 in coutp:
+                            ext = os.path.splitext(file2)[1][1:]
+                            if ext.lower() in extensions:
+                                files2.append(os.path.join(cpth, file2))
+                    else:
+                        files2.append(None)
+
+            if self.cmp_namefile is None:
+                pth = None
+            else:
+                pth = os.path.join(cpth, self.cmp_namefile)
+
+            for i in range(len(files1)):
+                file1 = files1[i]
+                ext = os.path.splitext(file1)[1][1:].lower()
+                outfile = os.path.splitext(os.path.basename(file1))[0]
+                outfile = os.path.join(
+                    self.workspace, outfile + "." + ext + ".cmp.out"
+                )
+                file2 = None if files2 is None else files2[i]
+
+                # set exfile
+                exfile = None
+                if file2 is None:
+                    if len(exfiles) > 0:
+                        exfile = exfiles[i]
+                        if exfile is not None:
+                            print(
+                                f"Exclusion file {i + 1}",
+                                os.path.basename(exfile),
+                            )
+
+                # make comparison
+                success = compare_heads(
+                    None,
+                    pth,
+                    precision="double",
+                    text=EXTTEXT[ext],
+                    outfile=outfile,
+                    files1=file1,
+                    files2=file2,
+                    htol=htol,
+                    difftol=True,
+                    verbose=self.verbose,
+                    exfile=exfile,
+                )
+                print(f"{EXTTEXT[ext]} comparison {i + 1}", self.name)
+                if not success:
+                    return False
+            return True
+
+        # otherwise it's a regression comparison
+        files0, files1 = get_regression_files(self.workspace, extensions)
+        extension = "hds"
+        for i, (fpth0, fpth1) in enumerate(zip(files0, files1)):
+            outfile = os.path.splitext(os.path.basename(fpth0))[0]
+            outfile = os.path.join(
+                self.workspace, outfile + f".{extension}.cmp.out"
+            )
+            success = compare_heads(
+                None,
+                None,
+                precision="double",
+                htol=htol,
+                text=EXTTEXT[extension],
+                outfile=outfile,
+                files1=fpth0,
+                files2=fpth1,
+                verbose=self.verbose,
+            )
+            print(
+                (
+                    f"{EXTTEXT[extension]} comparison {i + 1}"
+                    + f"{self.name} ({os.path.basename(fpth0)})"
+                )
+            )
+            if not success:
+                return False
+        return True
+
+    def _compare_concentrations(self, extensions="ucn", htol=0.001) -> bool:
+        if isinstance(extensions, str):
+            extensions = [extensions]
+
+        files0, files1 = get_regression_files(self.workspace, extensions)
+        extension = "ucn"
+        for i, (fpth0, fpth1) in enumerate(zip(files0, files1)):
+            outfile = os.path.splitext(os.path.basename(fpth0))[0]
+            outfile = os.path.join(
+                self.workspace, outfile + f".{extension}.cmp.out"
+            )
+            success = compare_heads(
+                None,
+                None,
+                precision="double",
+                htol=htol,
+                text=EXTTEXT[extension],
+                outfile=outfile,
+                files1=fpth0,
+                files2=fpth1,
+                verbose=self.verbose,
+            )
+            print(
+                (
+                    f"{EXTTEXT[extension]} comparison {i + 1}"
+                    + f"{self.name} ({os.path.basename(fpth0)})",
+                )
+            )
+            if not success:
+                return False
+        return True
+
+    def _compare_budgets(self, extensions="cbc", rclose=0.001) -> bool:
+        if isinstance(extensions, str):
+            extensions = [extensions]
+        files0, files1 = get_regression_files(self.workspace, extensions)
+        extension = "cbc"
+        for i, (fpth0, fpth1) in enumerate(zip(files0, files1)):
+            print(
+                f"{EXTTEXT[extension]} comparison {i + 1}",
+                f"{self.name} ({os.path.basename(fpth0)})",
+            )
+            success = self._compare_budget_files(
+                extension, fpth0, fpth1, rclose
+            )
+            if not success:
+                return False
+        return True
+
+    def _compare_budget_files(
+        self, extension, fpth0, fpth1, rclose=0.001
+    ) -> bool:
+        success = True
+        if os.stat(fpth0).st_size * os.stat(fpth0).st_size == 0:
+            return success, ""
+        outfile = os.path.splitext(os.path.basename(fpth0))[0]
+        outfile = os.path.join(
+            self.workspace, outfile + f".{extension}.cmp.out"
+        )
+        fcmp = open(outfile, "w")
+        fcmp.write("Performing CELL-BY-CELL to CELL-BY-CELL comparison\n")
+        fcmp.write(f"{fpth0}\n")
+        fcmp.write(f"{fpth1}\n\n")
+
+        # open the files
+        cbc0 = flopy.utils.CellBudgetFile(
+            fpth0, precision="double", verbose=self.verbose
+        )
+        cbc1 = flopy.utils.CellBudgetFile(
+            fpth1, precision="double", verbose=self.verbose
+        )
+
+        # build list of cbc data to retrieve
+        avail0 = cbc0.get_unique_record_names()
+        avail1 = cbc1.get_unique_record_names()
+        avail0 = [t.decode().strip() for t in avail0]
+        avail1 = [t.decode().strip() for t in avail1]
+
+        # initialize list for storing totals for each budget term terms
+        cbc_keys0 = []
+        cbc_keys1 = []
+        for t in avail0:
+            t1 = t
+            if t not in avail1:
+                # check if RCHA or EVTA is available and use that instead
+                # should be able to remove this once v6.3.0 is released
+                if t[:-1] in avail1:
+                    t1 = t[:-1]
+                else:
+                    raise Exception(f"Could not find {t} in {fpth1}")
+            cbc_keys0.append(t)
+            cbc_keys1.append(t1)
+
+        # get list of times and kstpkper
+        kk = cbc0.get_kstpkper()
+        times = cbc0.get_times()
+
+        # process data
+        for key, key1 in zip(cbc_keys0, cbc_keys1):
+            for idx, (k, t) in enumerate(zip(kk, times)):
+                v0 = cbc0.get_data(kstpkper=k, text=key)[0]
+                v1 = cbc1.get_data(kstpkper=k, text=key1)[0]
+                if v0.dtype.names is not None:
+                    v0 = v0["q"]
+                    v1 = v1["q"]
+                # skip empty vectors
+                if v0.size < 1:
+                    continue
+                vmin = rclose
+                if vmin < 1e-6:
+                    vmin = 1e-6
+                vmin_tol = 5.0 * vmin
+                if v0.shape != v1.shape:
+                    v0 = v0.flatten()
+                    v1 = v1.flatten()
+                idx = (abs(v0) > vmin) & (abs(v1) > vmin)
+                diff = np.zeros(v0.shape, dtype=v0.dtype)
+                diff[idx] = abs(v0[idx] - v1[idx])
+                diffmax = diff.max()
+                indices = np.where(diff == diffmax)[0]
+                if diffmax > vmin_tol:
+                    success = False
+                    msg = (
+                        f"{os.path.basename(fpth0)} - "
+                        + f"{key:16s} "
+                        + f"difference ({diffmax:10.4g}) "
+                        + f"> {vmin_tol:10.4g} "
+                        + f"at {indices.size} nodes "
+                        + f" [first location ({indices[0] + 1})] "
+                        + f"at time {t} "
+                    )
+                    fcmp.write(f"{msg}\n")
+                    if self.verbose:
+                        print(msg)
+
+        fcmp.close()
+        return success
+
+    # public
+
+    def setup(self, src, dst):
+        print("Setting up MF6 test", self.name)
+        print("  Source:", src)
+        print("  Destination:", dst)
+        self.workspace = dst
+
+        # setup workspace and expected output files
+        _, self.outp = setup_mf6(src=src, dst=dst)
+        print("waiting...")
+        time.sleep(0.5)
+
+        if self.compare == "mf6_regression":
+            shutil.copytree(self.workspace, self.workspace / self.compare)
+        else:
+            self.compare = get_mf6_comparison(src)  # detect comparison
+            setup_mf6_comparison(src, dst, self.compare, overwrite=True)
+
+    def run_sim_or_model(
+        self,
+        workspace: Union[str, os.PathLike],
+        target: Union[str, os.PathLike],
+        xfail: bool = False,
+        ncpus: int = 1,
+    ) -> Tuple[bool, List[str]]:
         """
-        Build base and regression MODFLOW 6 models
-
-        Parameters
-        ----------
-        build_function : function
-            user defined function that builds a base model and optionally
-            builds a regression model. If a regression model is not built
-            then None must be returned from the function for the regression
-            model.
-        idx : int
-            counter that corresponds to exdir entry
-        exdir : str
-            path to regression model files
+        Run a simulation or model with FloPy.
+
+        workspace : str or path-like
+            The simulation or model workspace
+        target : str or path-like
+            The target executable to use
+        xfail : bool
+            Whether to expect failure
+        ncpus : int
+            The number of CPUs for a parallel run
         """
-        base, regression = build_function(idx, exdir)
-        base.write_simulation()
-        if regression is not None:
-            if isinstance(regression, flopy.mf6.MFSimulation):
-                regression.write_simulation()
+
+        # make sure workspace exists
+        workspace = Path(workspace).expanduser().absolute()
+        assert workspace.is_dir(), f"Workspace not found: {workspace}"
+
+        # make sure executable exists and framework knows about it
+        tgt = Path(shutil.which(target))
+        assert tgt.is_file(), f"Target executable not found: {target}"
+        assert (
+            tgt in self.targets.values()
+        ), f"Targets must be explicitly registered with the test framework"
+
+        if self.verbose:
+            print(f"Running {target} in {workspace}")
+
+        # needed in _compare_heads()... todo: inject explicitly?
+        nf = next(iter(get_namefiles(workspace)), None)
+        self.cmp_namefile = (
+            None
+            if "mf6" in target.name or "libmf6" in target.name
+            else os.path.basename(nf)
+            if nf
+            else None
+        )
+
+        # run the model
+        try:
+            # via MODFLOW API
+            if "libmf6" in target.name and self.api_func:
+                success, buff = self.api_func(target, workspace)
+            # via MF6 executable
+            elif "mf6" in target.name:
+                # parallel test if configured
+                if self.parallel and ncpus > 1:
+                    print(
+                        f"Parallel test {self.name} on {self.ncpus} processes"
+                    )
+                    try:
+                        success, buff = run_parallel(workspace, target, ncpus)
+                    except Exception:
+                        warn(
+                            "MODFLOW 6 parallel test",
+                            self.name,
+                            f"failed with error:\n{format_exc()}",
+                        )
+                        success = False
+                else:
+                    # otherwise serial run
+                    try:
+                        success, buff = flopy.run_model(
+                            target,
+                            self.workspace / "mfsim.nam",
+                            model_ws=workspace,
+                            report=True,
+                        )
+                    except Exception:
+                        warn(
+                            "MODFLOW 6 serial test",
+                            self.name,
+                            f"failed with error:\n{format_exc()}",
+                        )
+                        success = False
             else:
-                regression.write_input()
+                # non-MF6 model
+                try:
+                    success, buff = flopy.run_model(
+                        target, self.cmp_namefile, workspace, report=True
+                    )
+                except Exception:
+                    warn(f"{target} model failed:\n{format_exc()}")
+                    success = False
 
-    def run(self, sim, workspace=None):
+            if xfail:
+                if success:
+                    warn("MODFLOW 6 model should have failed!")
+                    success = False
+                else:
+                    success = True
+
+            lst_file_path = Path(workspace) / "mfsim.lst"
+            if (
+                "mf6" in target.name
+                and not success
+                and lst_file_path.is_file()
+            ):
+                warn(
+                    "MODFLOW 6 listing file ended with: \n"
+                    + get_mfsim_lst_tail(lst_file_path)
+                )
+        except Exception:
+            success = False
+            warn(
+                f"Unhandled error in comparison model {self.name}:\n{format_exc()}"
+            )
+
+        return success, buff
+
+    def compare_output(self, compare):
         """
-        Run the MODFLOW 6 simulation and compare to existing head file or
-        appropriate MODFLOW-2005, MODFLOW-NWT, MODFLOW-USG, or MODFLOW-LGR run.
-
-        Parameters
-        ----------
-        sim : Simulation object
-            MODFLOW 6 autotest simulation object that runs the base and
-            regression models, compares the results, and tears down the
-            test if successful.
-        workspace : str
-            The path to the workspace where the test is run.
+        Compare the main simulation's output with that of another simulation or model.
+
+        compare : str
+            The comparison executable name: mf6, mf6_regression, libmf6, mf2005,
+            mfnwt, mflgr, or mfusg.
+        """
+
+        if compare not in COMPARE_PROGRAMS:
+            raise ValueError(f"Unsupported comparison program: {compare}")
+
+        if self.verbose:
+            print("Comparison test", self.name)
+
+        # adjust htol if < IMS outer_dvclose, and rclose for budget comparisons
+        htol = adjust_htol(self.workspace, self.htol)
+        rclose = get_rclose(self.workspace)
+        cmp_path = self.workspace / compare
+        if "mf6_regression" in compare:
+            assert self._compare_heads(
+                extensions=HDS_EXT, htol=htol
+            ), "head comparison failed"
+            assert self._compare_budgets(
+                extensions=CBC_EXT, rclose=rclose
+            ), "budget comparison failed"
+            assert self._compare_concentrations(
+                htol=htol
+            ), "concentration comparison failed"
+        else:
+            assert self._compare_heads(
+                cpth=cmp_path,
+                extensions=HDS_EXT,
+                mf6="mf6" in compare,
+                htol=htol,
+            ), "head comparison failed"
+
+    def run(self):
+        """
+        Run the test case end-to-end.
+
         """
 
-        sim.set_model(
-            sim.name if workspace is None else workspace, testModel=False
+        # if build fn provided, build models/simulations and write input files
+        if self.build:
+            sims = self.build(self)
+            sims = sims if isinstance(sims, Iterable) else [sims]
+            sims = [sim for sim in sims if sim]  # filter Nones
+            self.sims = sims
+            nsims = len(sims)
+            self.buffs = list(repeat(None, nsims))
+
+            assert len(self.xfail) in [
+                1,
+                nsims,
+            ], f"Invalid xfail: expected a single boolean or one for each model"
+            if len(self.xfail) == 1 and nsims:
+                self.xfail = list(repeat(self.xfail[0], nsims))
+
+            assert len(self.ncpus) in [
+                1,
+                nsims,
+            ], f"Invalid ncpus: expected a single integer or one for each model"
+            if len(self.ncpus) == 1 and nsims:
+                self.ncpus = list(repeat(self.ncpus[0], nsims))
+
+            write_input(*sims, overwrite=self.overwrite, verbose=self.verbose)
+        else:
+            self.sims = [MFSimulation.load(sim_ws=self.workspace)]
+            self.buffs = [None]
+            assert (
+                len(self.xfail) == 1
+            ), f"Invalid xfail: expected a single boolean"
+            assert (
+                len(self.ncpus) == 1
+            ), f"Invalid ncpus: expected a single integer"
+
+        # run models/simulations
+        for i, sim_or_model in enumerate(self.sims):
+            tgts = self.targets
+            workspace = get_workspace(sim_or_model)
+            exe_path = (
+                Path(sim_or_model.exe_name)
+                if sim_or_model.exe_name
+                else tgts["mf6"]
+            )
+            target = (
+                exe_path
+                if exe_path in tgts.values()
+                else tgts.get(exe_path.stem, tgts["mf6"])
+            )
+            xfail = self.xfail[i]
+            ncpus = self.ncpus[i]
+            success, buff = self.run_sim_or_model(
+                workspace, target, xfail, ncpus
+            )
+            self.buffs[i] = buff  # store model output for assertions later
+            assert success, (
+                f"{'Simulation' if 'mf6' in str(target) else 'Model'} "
+                f"{'should have failed' if xfail else 'failed'}: {workspace}"
+            )
+
+        # get expected output files from main simulation
+        _, self.outp = get_mf6_files(
+            self.workspace / "mfsim.nam", self.verbose
         )
-        sim.run()
-        sim.compare()
-        if sim.exfunc is not None:
-            sim.exfunc(sim)
+
+        # setup and run comparison model(s), if enabled
+        if self.compare:
+            # try to autodetect comparison type if enabled
+            if self.compare == "auto":
+                if self.verbose:
+                    print("Auto-detecting comparison type")
+                self.compare = get_mf6_comparison(self.workspace)
+            if self.compare:
+                if self.verbose:
+                    print(f"Using comparison type: {self.compare}")
+
+                # copy simulation files to comparison workspace if mf6 regression
+                if self.compare == "mf6_regression":
+                    cmp_path = self.workspace / self.compare
+                    if os.path.isdir(cmp_path):
+                        if self.verbose:
+                            print(f"Cleaning {cmp_path}")
+                        shutil.rmtree(cmp_path)
+                    if self.verbose:
+                        print(
+                            f"Copying simulation files from {self.workspace} to {cmp_path}"
+                        )
+                    shutil.copytree(self.workspace, cmp_path)
+
+                # run comparison simulation if libmf6 or mf6 regression
+                if self.compare in ["mf6_regression", "libmf6"]:
+                    # todo: don't hardcode workspace or assume agreement with test case
+                    # simulation workspace, set & access simulation workspaces directly
+                    workspace = self.workspace / self.compare
+                    success, _ = self.run_sim_or_model(
+                        workspace,
+                        self.targets.get(self.compare, self.targets["mf6"]),
+                    )
+                    assert success, f"Comparison model failed: {workspace}"
+
+                # compare model results, if enabled
+                if self.verbose:
+                    print("Comparing outputs")
+                self.compare_output(self.compare)
+
+        # check results, if enabled
+        if self.check:
+            if self.verbose:
+                print("Checking outputs")
+            self.check(self)
diff --git a/autotest/get_exes.py b/autotest/get_exes.py
index 0a071d50fea..d5c789ceb11 100644
--- a/autotest/get_exes.py
+++ b/autotest/get_exes.py
@@ -1,15 +1,18 @@
 import argparse
+from os import environ
 from pathlib import Path
+from platform import system
 from tempfile import TemporaryDirectory
 from warnings import warn
 
 import flopy
 import pytest
-from conftest import project_root_path
 from flaky import flaky
 from modflow_devtools.build import meson_build
 from modflow_devtools.download import download_and_unzip, get_release
-from modflow_devtools.misc import get_ostag
+from modflow_devtools.misc import get_ostag, is_in_ci, set_env
+
+from conftest import project_root_path
 
 repository = "MODFLOW-USGS/modflow6"
 top_bin_path = project_root_path / "bin"
@@ -73,11 +76,21 @@ def test_rebuild_release(rebuilt_bin_path: Path):
                 f.write(f"{line}\n")
 
         # rebuild with Meson
-        meson_build(
-            project_path=source_files_path.parent,
-            build_path=download_path / "builddir",
-            bin_path=rebuilt_bin_path,
-        )
+        def rebuild():
+            meson_build(
+                project_path=source_files_path.parent,
+                build_path=download_path / "builddir",
+                bin_path=rebuilt_bin_path,
+            )
+
+        # temp workaround until next release,
+        # ifx fails to build 6.4.2 on Windows
+        # most likely due to backspace issues
+        if system() == "Windows" and environ.get("FC") == "ifx":
+            with set_env(FC="ifort", CC="icl"):
+                rebuild()
+        else:
+            rebuild()
 
 
 @flaky(max_runs=3)
diff --git a/autotest/meson.build b/autotest/meson.build
new file mode 100644
index 00000000000..a36d6e1e82e
--- /dev/null
+++ b/autotest/meson.build
@@ -0,0 +1,34 @@
+test_drive = dependency('test-drive', required : false)
+if test_drive.found() and not fc_id.contains('intel')
+  tests = [
+    'ArrayHandlers',
+    'DevFeature',
+    'GeomUtil',
+    'HashTable',
+    'InputOutput',
+    'List',
+    'MathUtil',
+    'Message',
+    'Sim'
+  ]
+
+  test_srcs = files(
+    'tester.f90',
+  )
+  foreach t : tests
+    test_srcs += files('Test@0@.f90'.format(t.underscorify()))
+  endforeach
+
+  tester = executable(
+    'tester',
+    sources: test_srcs,
+    link_with: mf6core,
+    dependencies: test_drive,
+  )
+
+  test('Test source modules', tester)
+
+  foreach t : tests
+    test(t, tester, args: t)
+  endforeach
+endif
\ No newline at end of file
diff --git a/autotest/pytest.ini b/autotest/pytest.ini
index bc9cdb0cc74..b8e144f9f5c 100644
--- a/autotest/pytest.ini
+++ b/autotest/pytest.ini
@@ -1,4 +1,5 @@
 [pytest]
+addopts = --color=yes
 python_files =
     test_*.py
     *_test*.py
diff --git a/autotest/simulation.py b/autotest/simulation.py
deleted file mode 100644
index 73516fbfdee..00000000000
--- a/autotest/simulation.py
+++ /dev/null
@@ -1,784 +0,0 @@
-import os
-import shutil
-import sys
-import time
-from traceback import format_exc
-from subprocess import PIPE, STDOUT, Popen
-
-import flopy
-import numpy as np
-from common_regression import (
-    get_mf6_comparison,
-    get_mf6_files,
-    get_namefiles,
-    setup_mf6,
-    setup_mf6_comparison,
-)
-from flopy.utils.compare import compare_heads
-from modflow_devtools.misc import is_in_ci
-
-sfmt = "{:25s} - {}"
-extdict = {
-    "hds": "head",
-    "hed": "head",
-    "bhd": "head",
-    "ucn": "concentration",
-    "cbc": "cell-by-cell",
-}
-
-
-class TestSimulation:
-    # tell pytest this isn't a test class, don't collect it
-    __test__ = False
-
-    def __init__(
-        self,
-        name,
-        parallel=False,
-        ncpus=1,
-        exfunc=None,
-        exe_dict=None,
-        htol=None,
-        pdtol=None,
-        rclose=None,
-        idxsim=None,
-        cmp_verbose=True,
-        require_failure=None,
-        api_func=None,
-        mf6_regression=False,
-        make_comparison=True,
-        simpath=None,
-    ):
-        msg = sfmt.format("Initializing test", name)
-        print(msg)
-
-        self.name = name
-        self.parallel = parallel
-        self.ncpus = ncpus
-        self.exfunc = exfunc
-        self.targets = exe_dict
-        self.simpath = simpath
-        self.inpt = None
-        self.outp = None
-        self.coutp = None
-        self.api_func = api_func
-        self.mf6_regression = mf6_regression
-        self.make_comparison = make_comparison
-        self.action = None
-
-        # set htol for comparisons
-        if htol is None:
-            htol = 0.001
-        else:
-            msg = sfmt.format("User specified comparison htol", htol)
-            print(msg)
-
-        self.htol = htol
-
-        # set pdtol for comparisons
-        if pdtol is None:
-            pdtol = 0.001
-        else:
-            msg = sfmt.format(
-                "User specified percent difference comparison pdtol", pdtol
-            )
-            print(msg)
-
-        self.pdtol = pdtol
-
-        # set rclose for comparisons
-        if rclose is None:
-            rclose = 0.001
-        else:
-            msg = sfmt.format(
-                "User specified percent difference comparison rclose", rclose
-            )
-            print(msg)
-
-        self.rclose = rclose
-
-        # set index for multi-simulation comparisons
-        self.idxsim = idxsim
-
-        # set compare verbosity
-        self.cmp_verbose = cmp_verbose
-
-        # set allow failure
-        self.require_failure = require_failure
-
-        self.success = False
-
-        # set is_ci
-        self.is_CI = is_in_ci()
-
-        return
-
-    def __repr__(self):
-        return self.name
-
-    def set_model(self, pth, testModel=True):
-        """
-        Set paths to MODFLOW 6 model and associated comparison test
-        """
-        # make sure this is a valid path
-        if not os.path.isdir(pth):
-            assert False, f"{pth} is not a valid directory"
-
-        self.simpath = pth
-
-        # get MODFLOW 6 output file names
-        fpth = os.path.join(pth, "mfsim.nam")
-        mf6inp, mf6outp = get_mf6_files(fpth)
-        self.outp = mf6outp
-
-        # determine comparison model
-        self.setup_comparison(pth, pth, testModel=testModel)
-        # if self.mf6_regression:
-        #     self.action = "mf6_regression"
-        # else:
-        #     self.action = get_mf6_comparison(pth)
-        if self.action is not None:
-            if "mf6" in self.action or "mf6_regression" in self.action:
-                cinp, self.coutp = get_mf6_files(fpth)
-
-    def setup(self, src, dst):
-        msg = sfmt.format("Setting up test workspace", self.name)
-        print(msg)
-        self.originpath = src
-        self.simpath = dst
-        try:
-            self.inpt, self.outp = setup_mf6(src=src, dst=dst)
-            print("waiting...")
-            time.sleep(0.5)
-            success = True
-        except:
-            success = False
-            print(f"source:      {src}")
-            print(f"destination: {dst}")
-        assert success, f"Failed to set up test workspace: {format_exc()}"
-
-        if success:
-            self.setup_comparison(src, dst)
-
-        return
-
-    def setup_comparison(self, src, dst, testModel=True):
-
-        # evaluate if comparison should be made
-        if not self.make_comparison:
-            return
-
-        # adjust htol if it is smaller than IMS outer_dvclose
-        dvclose = self._get_dvclose(dst)
-        if dvclose is not None:
-            dvclose *= 5.0
-            if self.htol < dvclose:
-                self.htol = dvclose
-
-        # get rclose to use with budget comparisons
-        rclose = self._get_rclose(dst)
-        if rclose is None:
-            rclose = 0.5
-        else:
-            rclose *= 5.0
-        self.rclose = rclose
-
-        # Copy comparison simulations if available
-        if self.mf6_regression:
-            action = "mf6_regression"
-            pth = os.path.join(dst, action)
-            if os.path.isdir(pth):
-                shutil.rmtree(pth)
-            shutil.copytree(dst, pth)
-        elif testModel:
-            action = setup_mf6_comparison(src, dst, remove_existing=True)
-        else:
-            action = get_mf6_comparison(dst)
-
-        self.action = action
-
-        return
-
-    def run(self):
-        """
-        Run the model and assert if the model terminated successfully
-        """
-        msg = sfmt.format("Run test", self.name)
-        print(msg)
-
-        # Set nam as namefile name without path
-        nam = None
-
-        # run mf6 models
-        exe = str(self.targets["mf6"].absolute())
-        msg = sfmt.format("using executable", exe)
-        print(msg)
-
-        if self.parallel:
-            print("running parallel on", self.ncpus, "processes")
-            try:
-                success, buff = self.run_parallel(
-                    exe,
-                )
-            except Exception as exc:                
-                msg = sfmt.format("MODFLOW 6 run", self.name)
-                print(msg)
-                print(exc)
-                success = False
-        else:
-            try:
-                success, buff = flopy.run_model(
-                    exe,
-                    nam,
-                    model_ws=self.simpath,
-                    silent=False,
-                    report=True,
-                )
-                msg = sfmt.format("MODFLOW 6 run", self.name)
-                if success:
-                    print(msg)
-                else:
-                    print(msg)
-            except:
-                msg = sfmt.format("MODFLOW 6 run", self.name)
-                print(msg)
-                success = False
-
-        # set failure based on success and require_failure setting
-        if self.require_failure is None:
-            msg = "MODFLOW 6 model did not terminate normally"
-            if success:
-                failure = False
-            else:
-                failure = True
-        else:
-            if self.require_failure:
-                msg = "MODFLOW 6 model should have failed"
-                if not success:
-                    failure = False
-                else:
-                    failure = True
-            else:
-                msg = "MODFLOW 6 model should not have failed"
-                if success:
-                    failure = False
-                else:
-                    failure = True
-
-        # print end of mfsim.lst to the screen
-        if failure and self.is_CI:
-            fpth = os.path.join(self.simpath, "mfsim.lst")
-            msg = self._get_mfsim_listing(fpth) + msg
-
-        # test for failure
-        assert not failure, msg
-
-        self.nam_cmp = None
-        if success:
-            if self.action is not None:
-                if self.action.lower() == "compare":
-                    msg = sfmt.format("Comparison files", self.name)
-                    print(msg)
-                else:
-                    cpth = os.path.join(self.simpath, self.action)
-                    key = self.action.lower().replace(".cmp", "")
-                    exe = str(self.targets[key].absolute())
-                    msg = sfmt.format("comparison executable", exe)
-                    print(msg)
-                    if (
-                        "mf6" in key
-                        or "libmf6" in key
-                        or "mf6_regression" in key
-                    ):
-                        nam = None
-                    else:
-                        npth = get_namefiles(cpth)[0]
-                        nam = os.path.basename(npth)
-                    self.nam_cmp = nam
-                    try:
-                        if self.api_func is None:
-                            success_cmp, buff = flopy.run_model(
-                                exe,
-                                nam,
-                                model_ws=cpth,
-                                silent=False,
-                                report=True,
-                            )
-                        else:
-                            success_cmp, buff = self.api_func(
-                                exe, self.idxsim, model_ws=cpth
-                            )
-                        msg = sfmt.format(
-                            "Comparison run", self.name + "/" + key
-                        )
-                        print(msg)
-
-                        # print end of mfsim.lst to the screen
-                        if "mf6" in key:
-                            if not success and self.is_CI:
-                                fpth = os.path.join(cpth, "mfsim.lst")
-                                print(self._get_mfsim_listing(fpth))
-
-                    except:
-                        success_cmp = False
-                        msg = sfmt.format(
-                            "Comparison run", self.name + "/" + key
-                        )
-                        print(msg)
-
-                    assert success_cmp, "Unsuccessful comparison run"
-
-        return
-
-    def run_parallel(self, exe):
-        normal_msg="normal termination"
-        success = False
-        nr_success = 0
-        buff = []
-
-        mpiexec_cmd = ["mpiexec", "--oversubscribe", "-np", str(self.ncpus), exe, "-p"]
-        proc = Popen(mpiexec_cmd, stdout=PIPE, stderr=STDOUT, cwd=self.simpath)
-
-        while True:
-            line = proc.stdout.readline().decode("utf-8")
-            if line == "" and proc.poll() is not None:
-                break
-            if line:
-                # success is when the success message appears
-                # in every process of the parallel simulation
-                if normal_msg in line.lower():
-                    nr_success = nr_success + 1
-                    if nr_success == self.ncpus:
-                        success = True
-                line = line.rstrip("\r\n")
-                print(line)
-                buff.append(line)
-            else:
-                break
-
-        return success, buff
-
-
-    def compare(self):
-        """
-        Compare the model results
-
-        """
-        self.success = True
-
-        # evaluate if comparison should be made
-        if not self.make_comparison:
-            return
-
-        msgall = ""
-        msg = sfmt.format("Comparison test", self.name)
-        print(msg)
-
-        if self.action is not None:
-            cpth = os.path.join(self.simpath, self.action)
-            files_cmp = None
-            if self.action.lower() == "compare":
-                files_cmp = []
-                files = os.listdir(cpth)
-                for file in files:
-                    files_cmp.append(file)
-            elif "mf6" in self.action:
-                fpth = os.path.join(cpth, "mfsim.nam")
-                cinp, self.coutp = get_mf6_files(fpth)
-
-            head_extensions = (
-                "hds",
-                "hed",
-                "bhd",
-                "ahd",
-                "bin",
-            )
-            if "mf6_regression" in self.action:
-                success, msgall = self._compare_heads(
-                    msgall,
-                    extensions=head_extensions,
-                )
-                if not success:
-                    self.success = False
-            # non-regression runs - for new features
-            else:
-                files1 = []
-                files2 = []
-                exfiles = []
-                ipos = 0
-                for file1 in self.outp:
-                    ext = os.path.splitext(file1)[1][1:]
-
-                    if ext.lower() in head_extensions:
-
-                        # simulation file
-                        pth = os.path.join(self.simpath, file1)
-                        files1.append(pth)
-
-                        # look for an exclusion file
-                        pth = os.path.join(self.simpath, file1 + ".ex")
-                        if os.path.isfile(pth):
-                            exfiles.append(pth)
-                        else:
-                            exfiles.append(None)
-
-                        # Check to see if there is a corresponding compare file
-                        if files_cmp is not None:
-
-                            if file1 + ".cmp" in files_cmp:
-                                # compare file
-                                idx = files_cmp.index(file1 + ".cmp")
-                                pth = os.path.join(cpth, files_cmp[idx])
-                                files2.append(pth)
-                                txt = sfmt.format(
-                                    f"Comparison file {ipos + 1}",
-                                    os.path.basename(pth),
-                                )
-                                print(txt)
-                        else:
-                            if self.coutp is not None:
-                                for file2 in self.coutp:
-                                    ext = os.path.splitext(file2)[1][1:]
-
-                                    if ext.lower() in head_extensions:
-                                        # simulation file
-                                        pth = os.path.join(cpth, file2)
-                                        files2.append(pth)
-
-                            else:
-                                files2.append(None)
-
-                if self.nam_cmp is None:
-                    pth = None
-                else:
-                    pth = os.path.join(cpth, self.nam_cmp)
-
-                for ipos in range(len(files1)):
-                    file1 = files1[ipos]
-                    ext = os.path.splitext(file1)[1][1:].lower()
-                    outfile = os.path.splitext(os.path.basename(file1))[0]
-                    outfile = os.path.join(
-                        self.simpath, outfile + "." + ext + ".cmp.out"
-                    )
-                    if files2 is None:
-                        file2 = None
-                    else:
-                        file2 = files2[ipos]
-
-                    # set exfile
-                    exfile = None
-                    if file2 is None:
-                        if len(exfiles) > 0:
-                            exfile = exfiles[ipos]
-                            if exfile is not None:
-                                txt = sfmt.format(
-                                    f"Exclusion file {ipos + 1}",
-                                    os.path.basename(exfile),
-                                )
-                                print(txt)
-
-                    # make comparison
-                    success_tst = compare_heads(
-                        None,
-                        pth,
-                        precision="double",
-                        text=extdict[ext],
-                        outfile=outfile,
-                        files1=file1,
-                        files2=file2,
-                        htol=self.htol,
-                        difftol=True,
-                        # Change to true to have list of all nodes exceeding htol
-                        verbose=self.cmp_verbose,
-                        exfile=exfile,
-                    )
-                    msg = sfmt.format(
-                        f"{extdict[ext]} comparison {ipos + 1}",
-                        self.name,
-                    )
-                    print(msg)
-
-                    if not success_tst:
-                        self.success = False
-                        msgall += msg + " ... FAILED\n"
-
-            # compare concentrations
-            if "mf6_regression" in self.action:
-                success, msgall = self._compare_concentrations(msgall)
-                if not success:
-                    self.success = False
-
-            # compare cbc files
-            if "mf6_regression" in self.action:
-                cbc_extensions = (
-                    "cbc",
-                    "bud",
-                )
-                success, msgall = self._compare_budgets(
-                    msgall, extensions=cbc_extensions
-                )
-                if not success:
-                    self.success = False
-
-        assert self.success, msgall
-        return
-
-    def _get_mfsim_listing(self, lst_pth):
-        """Get the tail of the mfsim.lst listing file"""
-        msg = ""
-        ilen = 100
-        with open(lst_pth) as fp:
-            lines = fp.read().splitlines()
-        msg = "\n" + 79 * "-" + "\n"
-        if len(lines) > ilen:
-            i0 = -100
-        else:
-            i0 = 0
-        for line in lines[i0:]:
-            if len(line) > 0:
-                msg += f"{line}\n"
-        msg += 79 * "-" + "\n\n"
-        return msg
-
-    def _get_dvclose(self, dir_pth):
-        """Get outer_dvclose value from MODFLOW 6 ims file"""
-        dvclose = None
-        files = os.listdir(dir_pth)
-        for file_name in files:
-            pth = os.path.join(dir_pth, file_name)
-            if os.path.isfile(pth):
-                if file_name.lower().endswith(".ims"):
-                    with open(pth) as f:
-                        lines = f.read().splitlines()
-                    for line in lines:
-                        if "outer_dvclose" in line.lower():
-                            v = float(line.split()[1])
-                            if dvclose is None:
-                                dvclose = v
-                            else:
-                                if v > dvclose:
-                                    dvclose = v
-                            break
-
-        return dvclose
-
-    def _get_rclose(self, dir_pth):
-        """Get inner_rclose value from MODFLOW 6 ims file"""
-        rclose = None
-        files = os.listdir(dir_pth)
-        for file_name in files:
-            pth = os.path.join(dir_pth, file_name)
-            if os.path.isfile(pth):
-                if file_name.lower().endswith(".ims"):
-                    with open(pth) as f:
-                        lines = f.read().splitlines()
-                    for line in lines:
-                        if "inner_rclose" in line.lower():
-                            v = float(line.split()[1])
-                            if rclose is None:
-                                rclose = v
-                            else:
-                                if v > rclose:
-                                    rclose = v
-                            break
-
-        return rclose
-
-    def _regression_files(self, extensions):
-        if isinstance(extensions, str):
-            extensions = [extensions]
-        files = os.listdir(self.simpath)
-        files0 = []
-        files1 = []
-        for file_name in files:
-            fpth0 = os.path.join(self.simpath, file_name)
-            if os.path.isfile(fpth0):
-                for extension in extensions:
-                    if file_name.lower().endswith(extension):
-                        files0.append(fpth0)
-                        fpth1 = os.path.join(
-                            self.simpath, "mf6_regression", file_name
-                        )
-                        files1.append(fpth1)
-                        break
-        return files0, files1
-
-    def _compare_heads(self, msgall, extensions="hds"):
-        if isinstance(extensions, str):
-            extensions = [extensions]
-        success = True
-        files0, files1 = self._regression_files(extensions)
-        extension = "hds"
-        ipos = 0
-        for idx, (fpth0, fpth1) in enumerate(zip(files0, files1)):
-            outfile = os.path.splitext(os.path.basename(fpth0))[0]
-            outfile = os.path.join(
-                self.simpath, outfile + f".{extension}.cmp.out"
-            )
-            success_tst = compare_heads(
-                None,
-                None,
-                precision="double",
-                htol=self.htol,
-                text=extdict[extension],
-                outfile=outfile,
-                files1=fpth0,
-                files2=fpth1,
-                verbose=self.cmp_verbose,
-            )
-            msg = sfmt.format(
-                f"{extdict[extension]} comparison {ipos + 1}",
-                f"{self.name} ({os.path.basename(fpth0)})",
-            )
-            ipos += 1
-            print(msg)
-
-            if not success_tst:
-                success = False
-                msgall += msg + " ... FAILED\n"
-
-        return success, msgall
-
-    def _compare_concentrations(self, msgall, extensions="ucn"):
-        if isinstance(extensions, str):
-            extensions = [extensions]
-        success = True
-        files0, files1 = self._regression_files(extensions)
-        extension = "ucn"
-        ipos = 0
-        for idx, (fpth0, fpth1) in enumerate(zip(files0, files1)):
-            outfile = os.path.splitext(os.path.basename(fpth0))[0]
-            outfile = os.path.join(
-                self.simpath, outfile + f".{extension}.cmp.out"
-            )
-            success_tst = compare_heads(
-                None,
-                None,
-                precision="double",
-                htol=self.htol,
-                text=extdict[extension],
-                outfile=outfile,
-                files1=fpth0,
-                files2=fpth1,
-                verbose=self.cmp_verbose,
-            )
-            msg = sfmt.format(
-                f"{extdict[extension]} comparison {ipos + 1}",
-                f"{self.name} ({os.path.basename(fpth0)})",
-            )
-            ipos += 1
-            print(msg)
-
-            if not success_tst:
-                success = False
-                msgall += msg + " ... FAILED\n"
-
-        return success, msgall
-
-    def _compare_budgets(self, msgall, extensions="cbc"):
-        if isinstance(extensions, str):
-            extensions = [extensions]
-        success = True
-        files0, files1 = self._regression_files(extensions)
-        extension = "cbc"
-        ipos = 0
-        for idx, (fpth0, fpth1) in enumerate(zip(files0, files1)):
-            if os.stat(fpth0).st_size * os.stat(fpth0).st_size == 0:
-                continue
-            outfile = os.path.splitext(os.path.basename(fpth0))[0]
-            outfile = os.path.join(
-                self.simpath, outfile + f".{extension}.cmp.out"
-            )
-            fcmp = open(outfile, "w")
-
-            # open the files
-            cbc0 = flopy.utils.CellBudgetFile(
-                fpth0, precision="double", verbose=self.cmp_verbose
-            )
-            cbc1 = flopy.utils.CellBudgetFile(
-                fpth1, precision="double", verbose=self.cmp_verbose
-            )
-
-            # build list of cbc data to retrieve
-            avail0 = cbc0.get_unique_record_names()
-            avail1 = cbc1.get_unique_record_names()
-            avail0 = [t.decode().strip() for t in avail0]
-            avail1 = [t.decode().strip() for t in avail1]
-
-            # initialize list for storing totals for each budget term terms
-            cbc_keys0 = []
-            cbc_keys1 = []
-            for t in avail0:
-                t1 = t
-                if t not in avail1:
-                    # check if RCHA or EVTA is available and use that instead
-                    # should be able to remove this once v6.3.0 is released
-                    if t[:-1] in avail1:
-                        t1 = t[:-1]
-                    else:
-                        raise Exception(f"Could not find {t} in {fpth1}")
-                cbc_keys0.append(t)
-                cbc_keys1.append(t1)
-
-            # get list of times and kstpkper
-            kk = cbc0.get_kstpkper()
-            times = cbc0.get_times()
-
-            # process data
-            success_tst = True
-            for key, key1 in zip(cbc_keys0, cbc_keys1):
-                for idx, (k, t) in enumerate(zip(kk, times)):
-                    v0 = cbc0.get_data(kstpkper=k, text=key)[0]
-                    v1 = cbc1.get_data(kstpkper=k, text=key1)[0]
-                    if v0.dtype.names is not None:
-                        v0 = v0["q"]
-                        v1 = v1["q"]
-                    # skip empty vectors
-                    if v0.size < 1:
-                        continue
-                    vmin = self.rclose
-                    if vmin < 1e-6:
-                        vmin = 1e-6
-                    vmin_tol = 5.0 * vmin
-                    idx = (abs(v0) > vmin) & (abs(v1) > vmin)
-                    diff = np.zeros(v0.shape, dtype=v0.dtype)
-                    diff[idx] = abs(v0[idx] - v1[idx])
-                    diffmax = diff.max()
-                    indices = np.where(diff == diffmax)[0]
-                    if diffmax > vmin_tol:
-                        success_tst = False
-                        msg = (
-                            f"{os.path.basename(fpth0)} - "
-                            + f"{key:16s} "
-                            + f"difference ({diffmax:10.4g}) "
-                            + f"> {vmin_tol:10.4g} "
-                            + f"at {indices.size} nodes "
-                            + f" [first location ({indices[0] + 1})] "
-                            + f"at time {t} "
-                        )
-                        fcmp.write(f"{msg}\n")
-                        if self.cmp_verbose:
-                            print(msg)
-
-            msg = sfmt.format(
-                f"{extdict[extension]} comparison {ipos + 1}",
-                f"{self.name} ({os.path.basename(fpth0)})",
-            )
-            ipos += 1
-            print(msg)
-
-            fcmp.close()
-
-            if not success_tst:
-                success = False
-                msgall += msg + " ... FAILED\n"
-
-        return success, msgall
-
-
-def api_return(success, model_ws):
-    """
-    parse libmf6 stdout shared object file
-    """
-    fpth = os.path.join(model_ws, "mfsim.stdout")
-    return success, open(fpth).readlines()
diff --git a/autotest/test_cli.py b/autotest/test_cli.py
index aa9185ceb46..6cbf1bb2e0c 100644
--- a/autotest/test_cli.py
+++ b/autotest/test_cli.py
@@ -1,29 +1,21 @@
-import re
+import platform
 import subprocess
 
 from conftest import project_root_path
 
 bin_path = project_root_path / "bin"
-
-
-def split_nonnumeric(s):
-    match = re.compile("[^0-9]").search(s)
-    return [s[:match.start()], s[match.start():]] if match else s
+ext = ".exe" if platform.system() == "Windows" else ""
+exe = f"mf6{ext}"
 
 
 def test_cli_version():
     output = " ".join(
-        subprocess.check_output([str(bin_path / "mf6"), "-v"]).decode().split()
+        subprocess.check_output([str(bin_path / exe), "-v"]).decode().split()
     )
     print(output)
-    assert output.startswith("mf6:")
-
-    version = (
-        output.lower().split(' ')[1]
-    )
+    assert output.startswith(f"{exe}:"), f"found: {output}"
+    version = output.lower().split(" ")[1]
     print(version)
     v_split = version.split(".")
-    assert len(v_split) == 3
-    assert all(s.isdigit() for s in v_split[:2])
-    sol = split_nonnumeric(v_split[2])
-    assert sol[0].isdigit()
+    assert len(v_split) >= 2
+    assert all(s[-1].isdigit() for s in v_split[:2])
diff --git a/autotest/test_examples.py b/autotest/test_examples.py
new file mode 100644
index 00000000000..5262f6ed7cf
--- /dev/null
+++ b/autotest/test_examples.py
@@ -0,0 +1,60 @@
+import pytest
+
+from framework import TestFramework
+
+# skip nested models
+# ex-gwf-csub-p02c has subdirs like 'es-001', 'hb-100'
+# all others just have 2 folders 'mf6gwf' and 'mf6gwt'
+excluded_models = [
+    "ex-gwf-csub-p02c",
+    "ex-gwt-hecht-mendez-b",
+    "ex-gwt-hecht-mendez-c",
+    "ex-gwt-keating",
+    "ex-gwt-moc3d-p01a",
+    "ex-gwt-moc3d-p01b",
+    "ex-gwt-moc3d-p01c",
+    "ex-gwt-moc3d-p01d",
+    "ex-gwt-moc3d-p02",
+    "ex-gwt-moc3d-p02tg",
+    "ex-gwt-mt3dms-p02a",
+    "ex-gwt-mt3dms-p02b",
+    "ex-gwt-mt3dms-p02c",
+    "ex-gwt-mt3dms-p02d",
+    "ex-gwt-mt3dms-p02e",
+    "ex-gwt-mt3dms-p02f",
+    "ex-gwt-mt3dsupp631",
+    "ex-gwt-mt3dsupp632a",
+    "ex-gwt-mt3dsupp632b",
+    "ex-gwt-mt3dsupp632c",
+    "ex-gwt-mt3dsupp82",
+    "ex-gwt-prudic2004t2",
+]
+
+
+@pytest.mark.large
+@pytest.mark.repo
+@pytest.mark.regression
+@pytest.mark.slow
+def test_scenario(
+    # https://modflow-devtools.readthedocs.io/en/latest/md/fixtures.html#example-scenarios
+    function_tmpdir,
+    example_scenario,
+    targets,
+):
+    name, namefiles = example_scenario
+    if name in excluded_models:
+        pytest.skip(f"Skipping: {name} (excluded)")
+
+    model_paths = [nf.parent for nf in namefiles]
+    for model_path in model_paths:
+        model_name = f"{name}_{model_path.name}"
+        workspace = function_tmpdir / model_name
+        test = TestFramework(
+            name=model_name,
+            workspace=model_path,
+            targets=targets,
+            compare="mf6_regression",
+            verbose=False,
+        )
+        test.setup(model_path, workspace)
+        test.run()
diff --git a/autotest/test_gwf.py b/autotest/test_gwf.py
deleted file mode 100644
index 59e0d18f6ac..00000000000
--- a/autotest/test_gwf.py
+++ /dev/null
@@ -1,27 +0,0 @@
-from modflow_devtools.executables import Executables
-from pytest_cases import parametrize_with_cases
-from simulation import TestSimulation
-from test_gwf_maw04 import GwfMaw04Cases
-from test_gwf_maw_cases import GwfMawCases
-
-
-@parametrize_with_cases("case", cases=[GwfMawCases, GwfMaw04Cases])
-def test_gwf_models(case, targets: Executables):
-    data, sim, cmp, exfunc = case
-    sim.write_simulation()
-    if cmp:
-        cmp.write_simulation()
-
-    test = TestSimulation(
-        name=data.name,
-        exe_dict=targets,
-        exfunc=exfunc,
-        idxsim=0,  # TODO: remove parameter from TestSimulation
-        mf6_regression=True,
-        require_failure=data.xfail,
-        make_comparison=data.compare,
-    )
-
-    test.set_model(sim.simulation_data.mfpath.get_sim_path(), testModel=False)
-    test.run()
-    test.compare()
diff --git a/autotest/test_gwf_ats01.py b/autotest/test_gwf_ats01.py
index 167ce57ba35..a2becae2240 100644
--- a/autotest/test_gwf_ats01.py
+++ b/autotest/test_gwf_ats01.py
@@ -1,6 +1,5 @@
 """
 Test adaptive time step module
-
 """
 
 import os
@@ -8,10 +7,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["gwf_ats01a"]
+cases = ["gwf_ats01a"]
 nlay, nrow, ncol = 1, 1, 2
 
 # set dt0, dtmin, dtmax, dtadj, dtfailadj
@@ -22,7 +21,7 @@
 dtfailadj = 5.0
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     perlen = [10]
     nper = len(perlen)
     nstp = [1]
@@ -41,10 +40,10 @@ def build_model(idx, dir):
     for id in range(nper):
         tdis_rc.append((perlen[id], nstp[id], tsmult[id]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -175,11 +174,9 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_flow(sim):
-    print("evaluating flow...")
-
+def check_output(idx, test):
     # This will fail if budget numbers cannot be read
-    fpth = os.path.join(sim.simpath, f"{sim.name}.lst")
+    fpth = os.path.join(test.workspace, f"{test.name}.lst")
     mflist = flopy.utils.Mf6ListBudget(fpth)
     names = mflist.get_record_names()
     inc = mflist.get_incremental()
@@ -189,7 +186,7 @@ def eval_flow(sim):
     assert v == 10.0, f"Last time should be 10.  Found {v}"
 
     # ensure obs results changing monotonically
-    fpth = os.path.join(sim.simpath, sim.name + ".obs.csv")
+    fpth = os.path.join(test.workspace, test.name + ".obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -205,17 +202,13 @@ def eval_flow(sim):
     assert v == 10.0, f"Last time should be 10.  Found {v}"
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    workspace = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, workspace)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_flow, idxsim=0
-        ),
-        workspace,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_ats02.py b/autotest/test_gwf_ats02.py
index 7b41db9cfdc..7e03230de24 100644
--- a/autotest/test_gwf_ats02.py
+++ b/autotest/test_gwf_ats02.py
@@ -1,7 +1,6 @@
 """
 Test adaptive time step module with a one-d vertical column in which cells
 dry and then rewet based on a ghb in the bottom cell.
-
 """
 
 import os
@@ -9,10 +8,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["gwf_ats02a"]
+cases = ["gwf_ats02a"]
 nlay, nrow, ncol = 5, 1, 1
 botm = [80.0, 60.0, 40.0, 20.0, 0.0]
 
@@ -24,7 +23,7 @@
 dtfailadj = 5.0
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     perlen = [10, 10]
     nper = len(perlen)
     nstp = [5, 5]
@@ -42,10 +41,10 @@ def build_model(idx, dir):
     for id in range(nper):
         tdis_rc.append((perlen[id], nstp[id], tsmult[id]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -172,11 +171,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def make_plot(sim):
+def make_plot(test):
     print("making plots...")
-    ws = sim.simpath
+    ws = test.workspace
 
-    fname = sim.name + ".hds"
+    fname = test.name + ".hds"
     fname = os.path.join(ws, fname)
     hobj = flopy.utils.HeadFile(fname, precision="double")
     head = hobj.get_alldata()[:, :, 0, 0]
@@ -206,11 +205,9 @@ def make_plot(sim):
     plt.show()
 
 
-def eval_flow(sim):
-    print("evaluating flow...")
-
+def check_output(idx, test):
     # This will fail if budget numbers cannot be read
-    fpth = os.path.join(sim.simpath, f"{sim.name}.lst")
+    fpth = os.path.join(test.workspace, f"{test.name}.lst")
     mflist = flopy.utils.Mf6ListBudget(fpth)
     names = mflist.get_record_names()
     inc = mflist.get_incremental()
@@ -220,7 +217,7 @@ def eval_flow(sim):
     assert v == 20.0, f"Last time should be 20.  Found {v}"
 
     # ensure obs results changing monotonically
-    fpth = os.path.join(sim.simpath, sim.name + ".obs.csv")
+    fpth = os.path.join(test.workspace, test.name + ".obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -231,16 +228,13 @@ def eval_flow(sim):
     ), "layer 1 should be dry for this period"
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, 0, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_flow, idxsim=0
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_ats03.py b/autotest/test_gwf_ats03.py
index b36908ef866..7685321011f 100644
--- a/autotest/test_gwf_ats03.py
+++ b/autotest/test_gwf_ats03.py
@@ -7,7 +7,6 @@
 time zero and drops to 50.0 at time 100.  So the constant head values, which
 are observed and written to and obs output file must fall on a line between
 (0, 100) and (100, 50), which is ensured by this test.
-
 """
 
 import os
@@ -15,14 +14,14 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["gwf_ats03a"]
+cases = ["gwf_ats03a"]
 nlay, nrow, ncol = 1, 1, 10
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     perlen = [100.0]
     nper = len(perlen)
     nstp = [1]
@@ -41,10 +40,10 @@ def build_model(idx, dir):
     for id in range(nper):
         tdis_rc.append((perlen[id], nstp[id], tsmult[id]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -191,11 +190,9 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_flow(sim):
-    print("evaluating flow...")
-
+def check_output(idx, test):
     # ensure obs2 (a constant head time series) drops linearly from 100 to 50
-    fpth = os.path.join(sim.simpath, sim.name + ".obs.csv")
+    fpth = os.path.join(test.workspace, test.name + ".obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -207,16 +204,13 @@ def eval_flow(sim):
     assert np.allclose(answer, result), msg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, 0, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_flow, idxsim=0
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_ats_lak01.py b/autotest/test_gwf_ats_lak01.py
index 5f2381c08f3..90d9a0ad55d 100644
--- a/autotest/test_gwf_ats_lak01.py
+++ b/autotest/test_gwf_ats_lak01.py
@@ -1,16 +1,18 @@
-# Same as test_gwf_lak01 except it uses ATS.  Test works by trying a
-# large time step that does not converge.  ATS must then retry using
-# a smaller time step.
+"""
+Same as test_gwf_lak01 except it uses ATS.  Test works by trying a
+large time step that does not converge.  ATS must then retry using
+a smaller time step.
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["gwf_ats_lak_01a"]
+cases = ["gwf_ats_lak_01a"]
 gwf = None
 
 
@@ -21,7 +23,7 @@ def get_idomain(nlay, nrow, ncol, lakend):
     return idomain
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     lx = 300.0
     lz = 45.0
     nlay = 45
@@ -48,10 +50,10 @@ def build_model(idx, dir):
     nouter, ninner = 250, 300
     hclose, rclose, relax = 1e-8, 1e-6, 0.97
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -152,7 +154,7 @@ def build_model(idx, dir):
             irch[i, j] = k + 1
     nlakeconn = len(lake_vconnect)
 
-    # pak_data = [lakeno, strt, nlakeconn]
+    # pak_data = [ifno, strt, nlakeconn]
     initial_stage = 0.1
     pak_data = [(0, initial_stage, nlakeconn)]
 
@@ -257,7 +259,7 @@ def make_plot_xsect(sim, headall, stageall):
         # ax.set_ylim(-10, 5)
 
     fname = "fig-xsect.pdf"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(sim.workspace, fname)
     plt.savefig(fname, bbox_inches="tight")
 
 
@@ -274,7 +276,7 @@ def make_plot(sim, times, headall, stageall):
     ax.plot(times, h, "bo-", label="max head")
 
     fname = "fig-timeseries.pdf"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(sim.workspace, fname)
     plt.savefig(fname, bbox_inches="tight")
 
 
@@ -288,19 +290,17 @@ def get_kij_from_node(node, nrow, ncol):
     return k, i, j
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # calculate volume of water and make sure it is conserved
-    fname = sim.name + ".lak.bin"
-    fname = os.path.join(sim.simpath, fname)
+    fname = test.name + ".lak.bin"
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     bobj = flopy.utils.HeadFile(fname, text="STAGE")
     times = bobj.get_times()
     stage = bobj.get_alldata()
 
-    fname = sim.name + ".cbc"
-    fname = os.path.join(sim.simpath, fname)
+    fname = test.name + ".cbc"
+    fname = os.path.join(test.workspace, fname)
     bobj = flopy.utils.CellBudgetFile(fname, precision="double", verbose=False)
     times = bobj.get_times()
     idomain = gwf.dis.idomain.array
@@ -308,7 +308,6 @@ def eval_results(sim):
 
     all_passed = True
     for itime, t in enumerate(times):
-
         print(f"processing totim {t}")
         stage_current = stage[itime].flatten()
         print(f"lake stage = {stage_current}")
@@ -343,8 +342,8 @@ def eval_results(sim):
                     print(msg)
     assert all_passed, "found recharge applied to cell beneath active lake"
 
-    fname = sim.name + ".hds"
-    fname = os.path.join(sim.simpath, fname)
+    fname = test.name + ".hds"
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     hobj = flopy.utils.HeadFile(fname)
     head = hobj.get_alldata()
@@ -410,16 +409,13 @@ def eval_results(sim):
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, 0, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=0
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_auxvars.py b/autotest/test_gwf_auxvars.py
index 412b53a8385..d80123906a4 100644
--- a/autotest/test_gwf_auxvars.py
+++ b/autotest/test_gwf_auxvars.py
@@ -1,18 +1,17 @@
 import os
-import sys
 
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["aux01"]
+from framework import DNODATA, TestFramework
+
+cases = ["aux01"]
 auxvar1 = 101.0
 auxvar2 = 102.0
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 10, 10
     nper = 3
     perlen = [1.0, 1.0, 1.0]
@@ -30,10 +29,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -176,15 +175,15 @@ def build_model(idx, dir):
     )
     # sfr.remove()
 
-    # <lakeno> <strt> <nlakeconn> [<aux(naux)>] [<boundname>]
+    # <ifno> <strt> <nlakeconn> [<aux(naux)>] [<boundname>]
     packagedata = [
         [0, 100.0, 1, auxvar1, auxvar2, "lake1"],
         [1, 100.0, 1, auxvar1, auxvar2, "lake2"],
     ]
-    # <lakeno> <iconn> <cellid(ncelldim)> <claktype> <bedleak> <belev> <telev> <connlen> <connwidth>
+    # <ifno> <iconn> <cellid(ncelldim)> <claktype> <bedleak> <belev> <telev> <connlen> <connwidth>
     connectiondata = [
-        [0, 0, (0, 1, 1), "vertical", "none", 0.0, 0.0, 0.0, 0.0],
-        [1, 0, (0, 2, 2), "vertical", "none", 0.0, 0.0, 0.0, 0.0],
+        [0, 0, (0, 1, 1), "vertical", DNODATA, 0.0, 0.0, 0.0, 0.0],
+        [1, 0, (0, 2, 2), "vertical", DNODATA, 0.0, 0.0, 0.0, 0.0],
     ]
     lak = flopy.mf6.ModflowGwflak(
         gwf,
@@ -202,14 +201,14 @@ def build_model(idx, dir):
     )
     # lak.remove()
 
-    # <iuzno> <cellid(ncelldim)> <landflag> <ivertcon> <surfdep> <vks> <thtr> <thts> <thti> <eps> [<boundname>]
+    # <ifno> <cellid(ncelldim)> <landflag> <ivertcon> <surfdep> <vks> <thtr> <thts> <thti> <eps> [<boundname>]
     packagedata = [
         [0, (0, nrow - 1, 5), 1, -1, 0.1, 0.01, 0.01, 0.1, 0.01, 3.5, "uz1"],
         [1, (0, nrow - 1, 6), 1, -1, 0.1, 0.01, 0.01, 0.1, 0.01, 3.5, "uz1"],
         [2, (0, nrow - 1, 7), 1, -1, 0.1, 0.01, 0.01, 0.1, 0.01, 3.5, "uz1"],
         [3, (0, nrow - 1, 8), 1, -1, 0.1, 0.01, 0.01, 0.1, 0.01, 3.5, "uz1"],
     ]
-    # <iuzno> <finf> <pet> <extdp> <extwc> <ha> <hroot> <rootact> [<aux(naux)>]
+    # <ifno> <finf> <pet> <extdp> <extwc> <ha> <hroot> <rootact> [<aux(naux)>]
     perioddata = []
     for p in packagedata:
         perioddata.append(
@@ -244,11 +243,9 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
+def check_output(idx, test):
     # maw budget aux variables
-    fpth = os.path.join(sim.simpath, "aux01.maw.bud")
+    fpth = os.path.join(test.workspace, "aux01.maw.bud")
     bobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     records = bobj.get_data(text="auxiliary")
     for r in records:
@@ -256,7 +253,7 @@ def eval_model(sim):
         assert np.allclose(r["AUX2"], auxvar2)
 
     # sfr budget aux variables
-    fpth = os.path.join(sim.simpath, "aux01.sfr.bud")
+    fpth = os.path.join(test.workspace, "aux01.sfr.bud")
     bobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     records = bobj.get_data(text="auxiliary")
     for r in records:
@@ -264,7 +261,7 @@ def eval_model(sim):
         assert np.allclose(r["AUX2"], auxvar2)
 
     # lak budget aux variables
-    fpth = os.path.join(sim.simpath, "aux01.maw.bud")
+    fpth = os.path.join(test.workspace, "aux01.maw.bud")
     bobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     records = bobj.get_data(text="auxiliary")
     for r in records:
@@ -272,7 +269,7 @@ def eval_model(sim):
         assert np.allclose(r["AUX2"], auxvar2)
 
     # uzf budget aux variables
-    fpth = os.path.join(sim.simpath, "aux01.uzf.bud")
+    fpth = os.path.join(test.workspace, "aux01.uzf.bud")
     bobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     records = bobj.get_data(text="auxiliary")
     for r in records:
@@ -280,7 +277,7 @@ def eval_model(sim):
         assert np.allclose(r["AUX2"], auxvar2)
 
     # gwf budget maw aux variables
-    fpth = os.path.join(sim.simpath, "aux01.cbc")
+    fpth = os.path.join(test.workspace, "aux01.cbc")
     bobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     records = bobj.get_data(text="maw")
     for r in records:
@@ -300,16 +297,13 @@ def eval_model(sim):
         assert np.allclose(r["AUX2"], auxvar2)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=idx
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_auxvars02.py b/autotest/test_gwf_auxvars02.py
index c9ef34ee4d5..b7c82acf1a0 100644
--- a/autotest/test_gwf_auxvars02.py
+++ b/autotest/test_gwf_auxvars02.py
@@ -1,16 +1,15 @@
 import os
-import sys
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["aux02"]
+cases = ["aux02"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 10, 10
     nper = 3
     perlen = [1.0, 1.0, 1.0]
@@ -28,10 +27,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -107,11 +106,9 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
+def check_output(idx, test):
     # maw budget aux variables
-    fpth = os.path.join(sim.simpath, "aux02.bud")
+    fpth = os.path.join(test.workspace, "aux02.bud")
     bobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     records = bobj.get_data(text="CHD")
     for r in records:
@@ -120,16 +117,13 @@ def eval_model(sim):
             assert np.allclose(r[aname], a)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=idx
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_boundname01.py b/autotest/test_gwf_boundname01.py
index 8a5ac6050cb..e10fdc54fa1 100644
--- a/autotest/test_gwf_boundname01.py
+++ b/autotest/test_gwf_boundname01.py
@@ -3,26 +3,21 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = [
+cases = [
     "bndname01",
 ]
 
 
-def build_model(idx, exdir):
-
-    sim = get_model(idx, exdir)
-
-    ws = os.path.join(exdir, "mf6")
-    mc = get_model(idx, ws)
-
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace)
+    mc = get_model(idx, os.path.join(test.workspace, "mf6"))
     return sim, mc
 
 
 def get_model(idx, ws):
-
     nlay, nrow, ncol = 1, 1, 100
     nper = 1
     perlen = [5.0]
@@ -51,7 +46,7 @@ def get_model(idx, ws):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
     sim = flopy.mf6.MFSimulation(
@@ -144,7 +139,7 @@ def get_model(idx, ws):
 
 def replace_quotes(idx, exdir):
     ws = os.path.join(exdir, "mf6")
-    gwfname = f"gwf_{ex[idx]}"
+    gwfname = f"gwf_{cases[idx]}"
     extensions = (".chd", ".chd.obs")
     for ext in extensions:
         fpth = os.path.join(ws, f"{gwfname}{ext}")
@@ -155,14 +150,12 @@ def replace_quotes(idx, exdir):
                 f.write(line.replace("'", '"').replace('face"s', "face's"))
 
 
-def eval_obs(sim):
-    print("evaluating observations results..." f"({sim.name})")
-
-    fpth = os.path.join(sim.simpath, f"gwf_{sim.name}.chd.obs.csv")
+def check_output(idx, test):
+    fpth = os.path.join(test.workspace, f"gwf_{test.name}.chd.obs.csv")
     obs0 = np.genfromtxt(fpth, delimiter=",", names=True)
     names0 = obs0.dtype.names
 
-    fpth = os.path.join(sim.simpath, "mf6", f"gwf_{sim.name}.chd.obs.csv")
+    fpth = os.path.join(test.workspace, "mf6", f"gwf_{test.name}.chd.obs.csv")
     obs1 = np.genfromtxt(fpth, delimiter=",", names=True)
     names1 = obs1.dtype.names
 
@@ -170,14 +163,13 @@ def eval_obs(sim):
     assert np.array_equal(obs0, obs1), "observations are not identical"
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, 0, str(function_tmpdir))
-    test.run(
-        TestSimulation(name=name, exe_dict=targets, idxsim=0),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_buy_lak01.py b/autotest/test_gwf_buy_lak01.py
index 7a12bb2cffa..8641c87d8b7 100644
--- a/autotest/test_gwf_buy_lak01.py
+++ b/autotest/test_gwf_buy_lak01.py
@@ -1,28 +1,30 @@
-# Test the buoyancy package and the variable density flows between the lake
-# and the gwf model.  This model has 4 layers and a lake incised within it.
-# The model is transient and has heads in the aquifer higher than the initial
-# stage in the lake.  As the model runs, the lake and aquifer equalize and
-# should end up at the same level.  The test ensures that the initial and
-# final water volumes in the entire system are the same.  There are three
-# different cases:
-#  1.  No buoyancy package
-#  2.  Buoyancy package with lake and aquifer density = 1000.
-#  3.  Buoyancy package with lake and aquifer density = 1024.5
+"""
+Test the buoyancy package and the variable density flows between the lake
+and the gwf model.  This model has 4 layers and a lake incised within it.
+The model is transient and has heads in the aquifer higher than the initial
+stage in the lake.  As the model runs, the lake and aquifer equalize and
+should end up at the same level.  The test ensures that the initial and
+final water volumes in the entire system are the same.  There are three
+different cases:
+ 1.  No buoyancy package
+ 2.  Buoyancy package with lake and aquifer density = 1000.
+ 3.  Buoyancy package with lake and aquifer density = 1024.5
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["buy_lak_01a"]  # , 'buy_lak_01b', 'buy_lak_01c']
+cases = ["buy_lak_01a"]  # , 'buy_lak_01b', 'buy_lak_01c']
 buy_on_list = [False]  # , True, True]
 concbuylist = [0.0]  # , 0., 35.]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     lx = 7.0
     lz = 4.0
     nlay = 4
@@ -49,10 +51,10 @@ def build_model(idx, dir):
     nouter, ninner = 700, 300
     hclose, rclose, relax = 1e-8, 1e-6, 0.97
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -130,14 +132,14 @@ def build_model(idx, dir):
         )
 
     nlakeconn = 11  # note: number of connections for this lake
-    # pak_data = [lakeno, strt, nlakeconn, dense, boundname]
+    # pak_data = [ifno, strt, nlakeconn, dense, boundname]
     pak_data = [(0, 2.25, nlakeconn, lake_dense)]
 
     connlen = delr / 2.0
     connwidth = delc
     bedleak = "None"
     con_data = [
-        # con_data=(lakeno,iconn,(cellid),claktype,bedleak,belev,telev,connlen,connwidth )
+        # con_data=(ifno,iconn,(cellid),claktype,bedleak,belev,telev,connlen,connwidth )
         (0, 0, (0, 0, 0), "HORIZONTAL", bedleak, 10, 10, connlen, connwidth),
         (0, 1, (1, 0, 1), "VERTICAL", bedleak, 10, 10, connlen, connwidth),
         (0, 2, (1, 0, 1), "HORIZONTAL", bedleak, 10, 10, connlen, connwidth),
@@ -208,20 +210,18 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # calculate volume of water and make sure it is conserved
-    gwfname = "gwf_" + sim.name
+    gwfname = "gwf_" + test.name
     fname = gwfname + ".lak.bin"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     bobj = flopy.utils.HeadFile(fname, text="STAGE")
     stage = bobj.get_alldata().flatten()
     # print(stage)
 
     fname = gwfname + ".hds"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     hobj = flopy.utils.HeadFile(fname)
     head = hobj.get_data()
@@ -252,16 +252,13 @@ def eval_results(sim):
     # assert False
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, 0, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=0
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_buy_lak02.py b/autotest/test_gwf_buy_lak02.py
index 514f3348da5..204cc382363 100644
--- a/autotest/test_gwf_buy_lak02.py
+++ b/autotest/test_gwf_buy_lak02.py
@@ -1,90 +1,285 @@
+"""
+Test the buoyancy package and the variable density flows between the lake
+and the gwf model.  This model has 4 layers and a lake incised within it.
+The model is transient and has heads in the aquifer higher than the initial
+stage in the lake.  As the model runs, the lake and aquifer equalize and
+should end up at the same level.  The test ensures that the initial and
+final water volumes in the entire system are the same.  This test is different
+from the previous test in that transport is active.  There are four
+different cases:
+    1.  lak and aquifer have concentration of 0.
+    2.  lak and aquifer have concentration of 35.
+    3.  lak has concentration of 0., aquifer is 35.
+    4.  lak has concentration of 35., aquifer is 0.
+"""
+
 import os
-from typing import NamedTuple
 
 import flopy
 import numpy as np
+import pytest
+
 from framework import TestFramework
-from pytest_cases import parametrize, parametrize_with_cases
-from simulation import TestSimulation
-
-
-class GwfBuyLakCases:
-    """
-    Test the buoyancy package and the variable density flows between the lake
-    and the gwf model.  This model has 4 layers and a lake incised within it.
-    The model is transient and has heads in the aquifer higher than the initial
-    stage in the lake.  As the model runs, the lake and aquifer equalize and
-    should end up at the same level.  The test ensures that the initial and
-    final water volumes in the entire system are the same.  This test is different
-    from the previous test in that transport is active.  There are four
-    different cases:
-     1.  lak and aquifer have concentration of 0.
-     2.  lak and aquifer have concentration of 35.
-     3.  lak has concentration of 0., aquifer is 35.
-     4.  lak has concentration of 35., aquifer is 0.
-    """
-
-    class Data(NamedTuple):
-        name: str
-        gwt_conc: float
-        lak_conc: float
-
-    @parametrize(
-        data=[
-            Data(name="a", gwt_conc=0, lak_conc=0),
-            Data(name="b", gwt_conc=35, lak_conc=35),
-            Data(name="c", gwt_conc=35, lak_conc=0),
-            Data(name="d", gwt_conc=0, lak_conc=35),
-        ]
+
+simname = "gwfbuylak02"
+cases = [
+    f"{simname}a",
+    f"{simname}b",
+    f"{simname}c",
+    f"{simname}d",
+]
+gwt_conc = [0, 35, 35, 0]
+lak_conc = [0, 35, 0, 35]
+
+
+def build_models(idx, test):
+    name = cases[idx]
+
+    lx = 7.0
+    lz = 4.0
+    nlay = 4
+    nrow = 1
+    ncol = 7
+    nper = 1
+    delc = 1.0
+    delr = lx / ncol
+    delz = lz / nlay
+    top = 4.0
+    botm = [3.0, 2.0, 1.0, 0.0]
+
+    perlen = [50.0]
+    nstp = [50]
+    tsmult = [1.0]
+
+    Kh = 1.0
+    Kv = 1.0
+
+    tdis_rc = []
+    for i in range(nper):
+        tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
+
+    nouter, ninner = 700, 300
+    hclose, rclose, relax = 1e-8, 1e-6, 0.97
+
+    # build MODFLOW 6 files
+    sim = flopy.mf6.MFSimulation(
+        sim_name=name,
+        version="mf6",
+        exe_name="mf6",
+        sim_ws=test.workspace,
+    )
+    # create tdis package
+    tdis = flopy.mf6.ModflowTdis(
+        sim, time_units="DAYS", nper=nper, perioddata=tdis_rc
     )
-    def case_generator(self, data, function_tmpdir):
-        lx = 7.0
-        lz = 4.0
-        nlay = 4
-        nrow = 1
-        ncol = 7
-        nper = 1
-        delc = 1.0
-        delr = lx / ncol
-        delz = lz / nlay
-        top = 4.0
-        botm = [3.0, 2.0, 1.0, 0.0]
-
-        perlen = [50.0]
-        nstp = [50]
-        tsmult = [1.0]
-
-        Kh = 1.0
-        Kv = 1.0
-
-        tdis_rc = []
-        for i in range(nper):
-            tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
-
-        nouter, ninner = 700, 300
-        hclose, rclose, relax = 1e-8, 1e-6, 0.97
-
-        # build MODFLOW 6 files
-        sim = flopy.mf6.MFSimulation(
-            sim_name=data.name,
-            version="mf6",
-            exe_name="mf6",
-            sim_ws=str(function_tmpdir),
-        )
-        # create tdis package
-        tdis = flopy.mf6.ModflowTdis(
-            sim, time_units="DAYS", nper=nper, perioddata=tdis_rc
-        )
 
-        # create gwf model
-        gwfname = "gwf_" + data.name
-        gwtname = "gwt_" + data.name
+    # create gwf model
+    gwfname = "gwf_" + name
+    gwtname = "gwt_" + name
+
+    gwf = flopy.mf6.ModflowGwf(sim, modelname=gwfname, newtonoptions="NEWTON")
+
+    imsgwf = flopy.mf6.ModflowIms(
+        sim,
+        print_option="ALL",
+        outer_dvclose=hclose,
+        outer_maximum=nouter,
+        under_relaxation="NONE",
+        inner_maximum=ninner,
+        inner_dvclose=hclose,
+        rcloserecord=f"{rclose} strict",
+        linear_acceleration="BICGSTAB",
+        scaling_method="NONE",
+        reordering_method="NONE",
+        relaxation_factor=relax,
+        filename=f"{gwfname}.ims",
+    )
 
-        gwf = flopy.mf6.ModflowGwf(
-            sim, modelname=gwfname, newtonoptions="NEWTON"
-        )
+    idomain = np.full((nlay, nrow, ncol), 1)
+    idomain[0, 0, 1:6] = 0
+    idomain[1, 0, 2:5] = 0
+    idomain[2, 0, 3:4] = 0
+    dis = flopy.mf6.ModflowGwfdis(
+        gwf,
+        nlay=nlay,
+        nrow=nrow,
+        ncol=ncol,
+        delr=delr,
+        delc=delc,
+        top=top,
+        botm=botm,
+        idomain=idomain,
+    )
+
+    # initial conditions
+    strt = np.zeros((nlay, nrow, ncol), dtype=float)
+    strt[0, 0, :] = 3.5
+    strt[1, 0, :] = 3.0
+    strt[1, 0, 1:6] = 2.5
+    strt[2, 0, :] = 2.0
+    strt[3, 0, :] = 1.0
+    ic = flopy.mf6.ModflowGwfic(gwf, strt=strt)
+
+    # node property flow
+    npf = flopy.mf6.ModflowGwfnpf(
+        gwf,
+        xt3doptions=False,
+        save_flows=True,
+        save_specific_discharge=True,
+        icelltype=1,
+        k=Kh,
+        k33=Kv,
+    )
+
+    sto = flopy.mf6.ModflowGwfsto(gwf, sy=0.3, ss=0.0, iconvert=1)
+
+    buy_on = True
+    if buy_on:
+        pd = [(0, 0.7, 0.0, gwtname, "CONCENTRATION")]
+        buy = flopy.mf6.ModflowGwfbuy(gwf, denseref=1000.0, packagedata=pd)
+
+    nlakeconn = 11  # note: number of connections for this lake
+    # pak_data = [ifno, strt, nlakeconn, testauxvar, concentration, boundname]
+    pak_data = [(0, 2.25, nlakeconn, 0.0, 0.0)]
+
+    connlen = delr / 2.0
+    connwidth = delc
+    bedleak = "None"
+    con_data = [
+        # con_data=(ifno,iconn,(cellid),claktype,bedleak,belev,telev,connlen,connwidth )
+        (
+            0,
+            0,
+            (0, 0, 0),
+            "HORIZONTAL",
+            bedleak,
+            10,
+            10,
+            connlen,
+            connwidth,
+        ),
+        (0, 1, (1, 0, 1), "VERTICAL", bedleak, 10, 10, connlen, connwidth),
+        (
+            0,
+            2,
+            (1, 0, 1),
+            "HORIZONTAL",
+            bedleak,
+            10,
+            10,
+            connlen,
+            connwidth,
+        ),
+        (0, 3, (2, 0, 2), "VERTICAL", bedleak, 10, 10, connlen, connwidth),
+        (
+            0,
+            4,
+            (2, 0, 2),
+            "HORIZONTAL",
+            bedleak,
+            10,
+            10,
+            connlen,
+            connwidth,
+        ),
+        (0, 5, (3, 0, 3), "VERTICAL", bedleak, 10, 10, connlen, connwidth),
+        (
+            0,
+            6,
+            (2, 0, 4),
+            "HORIZONTAL",
+            bedleak,
+            10,
+            10,
+            connlen,
+            connwidth,
+        ),
+        (0, 7, (2, 0, 4), "VERTICAL", bedleak, 10, 10, connlen, connwidth),
+        (
+            0,
+            8,
+            (1, 0, 5),
+            "HORIZONTAL",
+            bedleak,
+            10,
+            10,
+            connlen,
+            connwidth,
+        ),
+        (0, 9, (1, 0, 5), "VERTICAL", bedleak, 10, 10, connlen, connwidth),
+        (
+            0,
+            10,
+            (0, 0, 6),
+            "HORIZONTAL",
+            bedleak,
+            10,
+            10,
+            connlen,
+            connwidth,
+        ),
+    ]
+
+    # period data
+    p_data = [
+        (0, "STATUS", "ACTIVE"),
+    ]
+
+    # note: for specifying lake number, use fortran indexing!
+    fname = f"{gwfname}.lak.obs.csv"
+    lak_obs = {
+        fname: [
+            ("lakestage", "stage", 1),
+            ("lakevolume", "volume", 1),
+            ("lak1", "lak", 1, 1),
+            ("lak2", "lak", 1, 2),
+            ("lak3", "lak", 1, 3),
+            ("lak4", "lak", 1, 4),
+            ("lak5", "lak", 1, 5),
+            ("lak6", "lak", 1, 6),
+            ("lak7", "lak", 1, 7),
+            ("lak8", "lak", 1, 8),
+            ("lak9", "lak", 1, 9),
+            ("lak10", "lak", 1, 10),
+            ("lak11", "lak", 1, 11),
+        ],
+        "digits": 10,
+    }
+
+    lak = flopy.mf6.modflow.ModflowGwflak(
+        gwf,
+        save_flows=True,
+        print_input=True,
+        print_flows=True,
+        print_stage=True,
+        stage_filerecord=f"{gwfname}.lak.bin",
+        budget_filerecord=f"{gwfname}.lak.bud",
+        nlakes=len(pak_data),
+        ntables=0,
+        packagedata=pak_data,
+        pname="LAK-1",
+        connectiondata=con_data,
+        perioddata=p_data,
+        observations=lak_obs,
+        auxiliary=["TESTAUXVAR", "CONCENTRATION"],
+    )
+
+    # output control
+    oc = flopy.mf6.ModflowGwfoc(
+        gwf,
+        budget_filerecord=f"{gwfname}.cbc",
+        head_filerecord=f"{gwfname}.hds",
+        headprintrecord=[("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")],
+        saverecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
+        printrecord=[("HEAD", "LAST"), ("BUDGET", "LAST")],
+    )
+
+    # create gwt model
+    transport = True
+    if transport:
+        gwt = flopy.mf6.ModflowGwt(sim, modelname=gwtname)
 
-        imsgwf = flopy.mf6.ModflowIms(
+        imsgwt = flopy.mf6.ModflowIms(
             sim,
             print_option="ALL",
             outer_dvclose=hclose,
@@ -97,15 +292,12 @@ def case_generator(self, data, function_tmpdir):
             scaling_method="NONE",
             reordering_method="NONE",
             relaxation_factor=relax,
-            filename=f"{gwfname}.ims",
+            filename=f"{gwtname}.ims",
         )
+        sim.register_ims_package(imsgwt, [gwt.name])
 
-        idomain = np.full((nlay, nrow, ncol), 1)
-        idomain[0, 0, 1:6] = 0
-        idomain[1, 0, 2:5] = 0
-        idomain[2, 0, 3:4] = 0
-        dis = flopy.mf6.ModflowGwfdis(
-            gwf,
+        dis = flopy.mf6.ModflowGwtdis(
+            gwt,
             nlay=nlay,
             nrow=nrow,
             ncol=ncol,
@@ -117,363 +309,150 @@ def case_generator(self, data, function_tmpdir):
         )
 
         # initial conditions
-        strt = np.zeros((nlay, nrow, ncol), dtype=float)
-        strt[0, 0, :] = 3.5
-        strt[1, 0, :] = 3.0
-        strt[1, 0, 1:6] = 2.5
-        strt[2, 0, :] = 2.0
-        strt[3, 0, :] = 1.0
-        ic = flopy.mf6.ModflowGwfic(gwf, strt=strt)
-
-        # node property flow
-        npf = flopy.mf6.ModflowGwfnpf(
-            gwf,
-            xt3doptions=False,
-            save_flows=True,
-            save_specific_discharge=True,
-            icelltype=1,
-            k=Kh,
-            k33=Kv,
-        )
+        ic = flopy.mf6.ModflowGwtic(gwt, strt=gwt_conc[idx])
 
-        sto = flopy.mf6.ModflowGwfsto(gwf, sy=0.3, ss=0.0, iconvert=1)
-
-        buy_on = True
-        if buy_on:
-            pd = [(0, 0.7, 0.0, gwtname, "CONCENTRATION")]
-            buy = flopy.mf6.ModflowGwfbuy(gwf, denseref=1000.0, packagedata=pd)
-
-        nlakeconn = 11  # note: number of connections for this lake
-        # pak_data = [lakeno, strt, nlakeconn, testauxvar, concentration, boundname]
-        pak_data = [(0, 2.25, nlakeconn, 0.0, 0.0)]
-
-        connlen = delr / 2.0
-        connwidth = delc
-        bedleak = "None"
-        con_data = [
-            # con_data=(lakeno,iconn,(cellid),claktype,bedleak,belev,telev,connlen,connwidth )
-            (
-                0,
-                0,
-                (0, 0, 0),
-                "HORIZONTAL",
-                bedleak,
-                10,
-                10,
-                connlen,
-                connwidth,
-            ),
-            (0, 1, (1, 0, 1), "VERTICAL", bedleak, 10, 10, connlen, connwidth),
-            (
-                0,
-                2,
-                (1, 0, 1),
-                "HORIZONTAL",
-                bedleak,
-                10,
-                10,
-                connlen,
-                connwidth,
-            ),
-            (0, 3, (2, 0, 2), "VERTICAL", bedleak, 10, 10, connlen, connwidth),
-            (
-                0,
-                4,
-                (2, 0, 2),
-                "HORIZONTAL",
-                bedleak,
-                10,
-                10,
-                connlen,
-                connwidth,
-            ),
-            (0, 5, (3, 0, 3), "VERTICAL", bedleak, 10, 10, connlen, connwidth),
-            (
-                0,
-                6,
-                (2, 0, 4),
-                "HORIZONTAL",
-                bedleak,
-                10,
-                10,
-                connlen,
-                connwidth,
-            ),
-            (0, 7, (2, 0, 4), "VERTICAL", bedleak, 10, 10, connlen, connwidth),
-            (
-                0,
-                8,
-                (1, 0, 5),
-                "HORIZONTAL",
-                bedleak,
-                10,
-                10,
-                connlen,
-                connwidth,
-            ),
-            (0, 9, (1, 0, 5), "VERTICAL", bedleak, 10, 10, connlen, connwidth),
-            (
-                0,
-                10,
-                (0, 0, 6),
-                "HORIZONTAL",
-                bedleak,
-                10,
-                10,
-                connlen,
-                connwidth,
-            ),
-        ]
+        # advection
+        adv = flopy.mf6.ModflowGwtadv(gwt, scheme="UPSTREAM")
 
-        # period data
-        p_data = [
-            (0, "STATUS", "ACTIVE"),
-        ]
+        # storage
+        porosity = 0.30
+        sto = flopy.mf6.ModflowGwtmst(gwt, porosity=porosity)
 
-        # note: for specifying lake number, use fortran indexing!
-        fname = f"{gwfname}.lak.obs.csv"
-        lak_obs = {
-            fname: [
-                ("lakestage", "stage", 1),
-                ("lakevolume", "volume", 1),
-                ("lak1", "lak", 1, 1),
-                ("lak2", "lak", 1, 2),
-                ("lak3", "lak", 1, 3),
-                ("lak4", "lak", 1, 4),
-                ("lak5", "lak", 1, 5),
-                ("lak6", "lak", 1, 6),
-                ("lak7", "lak", 1, 7),
-                ("lak8", "lak", 1, 8),
-                ("lak9", "lak", 1, 9),
-                ("lak10", "lak", 1, 10),
-                ("lak11", "lak", 1, 11),
-            ],
-            "digits": 10,
-        }
+        # sources
+        sourcerecarray = [
+            (),
+        ]
+        ssm = flopy.mf6.ModflowGwtssm(gwt, sources=sourcerecarray)
 
-        lak = flopy.mf6.modflow.ModflowGwflak(
-            gwf,
+        lktpackagedata = [
+            (0, lak_conc[idx], 99.0, 999.0, "mylake"),
+        ]
+        lkt = flopy.mf6.modflow.ModflowGwtlkt(
+            gwt,
+            boundnames=True,
             save_flows=True,
             print_input=True,
             print_flows=True,
-            print_stage=True,
-            stage_filerecord=f"{gwfname}.lak.bin",
-            budget_filerecord=f"{gwfname}.lak.bud",
-            nlakes=len(pak_data),
-            ntables=0,
-            packagedata=pak_data,
-            pname="LAK-1",
-            connectiondata=con_data,
-            perioddata=p_data,
-            observations=lak_obs,
-            auxiliary=["TESTAUXVAR", "CONCENTRATION"],
+            print_concentration=True,
+            concentration_filerecord=gwtname + ".lkt.bin",
+            budget_filerecord="gwtlak1.bud",
+            packagedata=lktpackagedata,
+            pname="LKT-1",
+            flow_package_name="LAK-1",
+            flow_package_auxiliary_name="CONCENTRATION",
+            auxiliary=["aux1", "aux2"],
         )
-
         # output control
-        oc = flopy.mf6.ModflowGwfoc(
-            gwf,
-            budget_filerecord=f"{gwfname}.cbc",
-            head_filerecord=f"{gwfname}.hds",
-            headprintrecord=[
+        oc = flopy.mf6.ModflowGwtoc(
+            gwt,
+            budget_filerecord=f"{gwtname}.cbc",
+            concentration_filerecord=f"{gwtname}.ucn",
+            concentrationprintrecord=[
                 ("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")
             ],
-            saverecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
-            printrecord=[("HEAD", "LAST"), ("BUDGET", "LAST")],
+            saverecord=[("CONCENTRATION", "ALL")],
+            printrecord=[("CONCENTRATION", "ALL"), ("BUDGET", "ALL")],
         )
 
-        # create gwt model
-        transport = True
-        if transport:
-            gwt = flopy.mf6.ModflowGwt(sim, modelname=gwtname)
-
-            imsgwt = flopy.mf6.ModflowIms(
-                sim,
-                print_option="ALL",
-                outer_dvclose=hclose,
-                outer_maximum=nouter,
-                under_relaxation="NONE",
-                inner_maximum=ninner,
-                inner_dvclose=hclose,
-                rcloserecord=f"{rclose} strict",
-                linear_acceleration="BICGSTAB",
-                scaling_method="NONE",
-                reordering_method="NONE",
-                relaxation_factor=relax,
-                filename=f"{gwtname}.ims",
-            )
-            sim.register_ims_package(imsgwt, [gwt.name])
-
-            dis = flopy.mf6.ModflowGwtdis(
-                gwt,
-                nlay=nlay,
-                nrow=nrow,
-                ncol=ncol,
-                delr=delr,
-                delc=delc,
-                top=top,
-                botm=botm,
-                idomain=idomain,
-            )
-
-            # initial conditions
-            strt = data.gwt_conc
-            ic = flopy.mf6.ModflowGwtic(gwt, strt=strt)
-
-            # advection
-            adv = flopy.mf6.ModflowGwtadv(gwt, scheme="UPSTREAM")
-
-            # storage
-            porosity = 0.30
-            sto = flopy.mf6.ModflowGwtmst(gwt, porosity=porosity)
-
-            # sources
-            sourcerecarray = [
-                (),
-            ]
-            ssm = flopy.mf6.ModflowGwtssm(gwt, sources=sourcerecarray)
-
-            lak_conc = data.lak_conc
-            lktpackagedata = [
-                (0, lak_conc, 99.0, 999.0, "mylake"),
-            ]
-            lkt = flopy.mf6.modflow.ModflowGwtlkt(
-                gwt,
-                boundnames=True,
-                save_flows=True,
-                print_input=True,
-                print_flows=True,
-                print_concentration=True,
-                concentration_filerecord=gwtname + ".lkt.bin",
-                budget_filerecord="gwtlak1.bud",
-                packagedata=lktpackagedata,
-                pname="LKT-1",
-                flow_package_name="LAK-1",
-                flow_package_auxiliary_name="CONCENTRATION",
-                auxiliary=["aux1", "aux2"],
-            )
-            # output control
-            oc = flopy.mf6.ModflowGwtoc(
-                gwt,
-                budget_filerecord=f"{gwtname}.cbc",
-                concentration_filerecord=f"{gwtname}.ucn",
-                concentrationprintrecord=[
-                    ("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")
-                ],
-                saverecord=[("CONCENTRATION", "ALL")],
-                printrecord=[("CONCENTRATION", "ALL"), ("BUDGET", "ALL")],
-            )
-
-            fmi = flopy.mf6.ModflowGwtfmi(gwt, flow_imbalance_correction=True)
-
-            # GWF GWT exchange
-            gwfgwt = flopy.mf6.ModflowGwfgwt(
-                sim,
-                exgtype="GWF6-GWT6",
-                exgmnamea=gwfname,
-                exgmnameb=gwtname,
-                filename=f"{data.name}.gwfgwt",
-            )
-
-        return data, sim, None, self.eval_results
-
-    def eval_results(self, sim, data):
-        print("evaluating results...")
-
-        # calculate volume of water and make sure it is conserved
-        gwfname = "gwf_" + data.name
-        gwtname = "gwt_" + data.name
-        fname = gwfname + ".lak.bin"
-        fname = os.path.join(sim.simpath, fname)
-        assert os.path.isfile(fname)
-        bobj = flopy.utils.HeadFile(fname, text="STAGE")
-        stage = bobj.get_alldata().flatten()
-        # print(stage)
-
-        fname = gwfname + ".hds"
-        fname = os.path.join(sim.simpath, fname)
-        assert os.path.isfile(fname)
-        hobj = flopy.utils.HeadFile(fname)
-        head = hobj.get_data()
-        # print(head)
-
-        fname = gwtname + ".ucn"
-        fname = os.path.join(sim.simpath, fname)
-        assert os.path.isfile(fname)
-        cobj = flopy.utils.HeadFile(fname, text="CONCENTRATION")
-        conc = cobj.get_data()
-
-        fname = gwtname + ".lkt.bin"
-        fname = os.path.join(sim.simpath, fname)
-        assert os.path.isfile(fname)
-        cobj = flopy.utils.HeadFile(fname, text="CONCENTRATION")
-        clak = cobj.get_data().flatten()
-
-        # calculate initial water volume
-        v0 = 3.5 * 2  # outermost columns
-        v0 += 2.5 * 2  # next innermost columns
-        v0 += 2.0 * 2  # next innermost columns
-        v0 += 1.0 * 1  # middle column
-        v0 = v0 * 0.3  # specific yield
-
-        m0 = v0 * data.gwt_conc
-        vl0 = (2.25 - 2.0) * 2 + (2.25 - 1.0)
-        m0 += vl0 * data.lak_conc
-        v0 += vl0
-        print(f"initial volume of water in model = {v0}")
-        print(f"initial mass of solute in model = {m0}")
-
-        # calculate ending water volume in model
-        head = np.where(head > 1e10, -1e10, head)
-        botm = [3, 2, 1, 0]
-        top = [4, 3, 2, 1]
-        nlay, nrow, ncol = head.shape
-        v = 0
-        m = 0.0
-        for k in range(nlay):
-            for i in range(nrow):
-                for j in range(ncol):
-                    h = min(head[k, i, j], top[k])
-                    dz = h - botm[k]
-                    vcell = max(dz, 0.0) * 0.3
-                    v += vcell
-                    m += vcell * conc[k, i, j]
-
-        s = stage[-1]
-        vl = (s - 2.0) * 2 + (s - 1.0)
-        v = v + vl
-        m += vl * clak[0]
-        print(f"final volume of water in model = {v}")
-        print(f"final mass of solute in model = {m}")
-
-        # check to make sure starting water volume same as equalized final volume
-        errmsg = f"initial and final water volume not equal: {v0} {v}"
-        assert np.allclose(v0, v), errmsg
-
-        # check to make sure starting starting solute mass same as equalized solute mass
-        errmsg = f"initial and final solute mass not equal: {m0} {m}"
-        assert np.allclose(m0, m), errmsg
-
-        # todo: add a better check of the lake concentrations
-
-
-@parametrize_with_cases(
-    "case",
-    cases=[
-        GwfBuyLakCases,
-    ],
-)
-def test_mf6model(case, targets):
-    data, sim, cmp, evl = case
-    sim.write_simulation()
-    if cmp:
-        cmp.write_simulation()
-
-    simulation = TestSimulation(
-        name=data.name, exe_dict=targets, exfunc=evl, idxsim=0
-    )
-    simulation.set_model(
-        sim.simulation_data.mfpath.get_sim_path(), testModel=False
+        fmi = flopy.mf6.ModflowGwtfmi(gwt, flow_imbalance_correction=True)
+
+        # GWF GWT exchange
+        gwfgwt = flopy.mf6.ModflowGwfgwt(
+            sim,
+            exgtype="GWF6-GWT6",
+            exgmnamea=gwfname,
+            exgmnameb=gwtname,
+            filename=f"{name}.gwfgwt",
+        )
+
+    return sim
+
+
+def check_output(idx, test):
+    # calculate volume of water and make sure it is conserved
+    gwfname = "gwf_" + test.name
+    gwtname = "gwt_" + test.name
+    fname = gwfname + ".lak.bin"
+    fname = os.path.join(test.workspace, fname)
+    assert os.path.isfile(fname)
+    bobj = flopy.utils.HeadFile(fname, text="STAGE")
+    stage = bobj.get_alldata().flatten()
+    # print(stage)
+
+    fname = gwfname + ".hds"
+    fname = os.path.join(test.workspace, fname)
+    assert os.path.isfile(fname)
+    hobj = flopy.utils.HeadFile(fname)
+    head = hobj.get_data()
+    # print(head)
+
+    fname = gwtname + ".ucn"
+    fname = os.path.join(test.workspace, fname)
+    assert os.path.isfile(fname)
+    cobj = flopy.utils.HeadFile(fname, text="CONCENTRATION")
+    conc = cobj.get_data()
+
+    fname = gwtname + ".lkt.bin"
+    fname = os.path.join(test.workspace, fname)
+    assert os.path.isfile(fname)
+    cobj = flopy.utils.HeadFile(fname, text="CONCENTRATION")
+    clak = cobj.get_data().flatten()
+
+    # calculate initial water volume
+    v0 = 3.5 * 2  # outermost columns
+    v0 += 2.5 * 2  # next innermost columns
+    v0 += 2.0 * 2  # next innermost columns
+    v0 += 1.0 * 1  # middle column
+    v0 = v0 * 0.3  # specific yield
+
+    m0 = v0 * gwt_conc[idx]
+    vl0 = (2.25 - 2.0) * 2 + (2.25 - 1.0)
+    m0 += vl0 * lak_conc[idx]
+    v0 += vl0
+    print(f"initial volume of water in model = {v0}")
+    print(f"initial mass of solute in model = {m0}")
+
+    # calculate ending water volume in model
+    head = np.where(head > 1e10, -1e10, head)
+    botm = [3, 2, 1, 0]
+    top = [4, 3, 2, 1]
+    nlay, nrow, ncol = head.shape
+    v = 0
+    m = 0.0
+    for k in range(nlay):
+        for i in range(nrow):
+            for j in range(ncol):
+                h = min(head[k, i, j], top[k])
+                dz = h - botm[k]
+                vcell = max(dz, 0.0) * 0.3
+                v += vcell
+                m += vcell * conc[k, i, j]
+
+    s = stage[-1]
+    vl = (s - 2.0) * 2 + (s - 1.0)
+    v = v + vl
+    m += vl * clak[0]
+    print(f"final volume of water in model = {v}")
+    print(f"final mass of solute in model = {m}")
+
+    # check to make sure starting water volume same as equalized final volume
+    errmsg = f"initial and final water volume not equal: {v0} {v}"
+    assert np.allclose(v0, v), errmsg
+
+    # check to make sure starting starting solute mass same as equalized solute mass
+    errmsg = f"initial and final solute mass not equal: {m0} {m}"
+    assert np.allclose(m0, m), errmsg
+
+    # todo: add a better check of the lake concentrations
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, targets, function_tmpdir):
+    framework = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
-    simulation.run()
-    simulation.compare()
-    evl(simulation, data)
+    framework.run()
diff --git a/autotest/test_gwf_buy_maw01.py b/autotest/test_gwf_buy_maw01.py
index 09e96b37579..8def29a12ae 100644
--- a/autotest/test_gwf_buy_maw01.py
+++ b/autotest/test_gwf_buy_maw01.py
@@ -1,29 +1,30 @@
-# Test the buoyancy package and the variable density flows between maw
-# and the gwf model.  This model has 4 layers with a single maw.
-# The model is transient and has heads in the aquifer higher than the initial
-# stage in the well.  As the model runs, the well and aquifer equalize and
-# should end up at the same level.  The test ensures that the initial and
-# final water volumes in the entire system are the same.  There are three
-# different cases:
-#  1.  No buoyancy package
-#  2.  Buoyancy package with maw and aquifer density = 1000.
-#  3.  Buoyancy package with maw and aquifer density = 1024.5
+"""
+Test the buoyancy package and the variable density flows between maw
+and the gwf model.  This model has 4 layers with a single maw.
+The model is transient and has heads in the aquifer higher than the initial
+stage in the well.  As the model runs, the well and aquifer equalize and
+should end up at the same level.  The test ensures that the initial and
+final water volumes in the entire system are the same.  There are three
+different cases:
+ 1.  No buoyancy package
+ 2.  Buoyancy package with maw and aquifer density = 1000.
+ 3.  Buoyancy package with maw and aquifer density = 1024.5
+"""
 
 import os
-import sys
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["buy_maw_01a"]  # , 'buy_maw_01b', 'buy_maw_01c']
+cases = ["buy_maw_01a"]  # , 'buy_maw_01b', 'buy_maw_01c']
 buy_on_list = [False]  # , True, True]
 concbuylist = [0.0]  # , 0., 35.]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     lx = 7.0
     lz = 4.0
     nlay = 4
@@ -50,10 +51,10 @@ def build_model(idx, dir):
     nouter, ninner = 700, 10
     hclose, rclose, relax = 1e-8, 1e-6, 0.97
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -128,16 +129,16 @@ def build_model(idx, dir):
     mawstrt = 3.5
     mawcondeqn = "THIEM"
     mawngwfnodes = nlay
-    # <wellno> <radius> <bottom> <strt> <condeqn> <ngwfnodes>
+    # <ifno> <radius> <bottom> <strt> <condeqn> <ngwfnodes>
     mawpackagedata = [
         [0, mawradius, mawbottom, mawstrt, mawcondeqn, mawngwfnodes, mawdense]
     ]
-    # <wellno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
+    # <ifno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
     mawconnectiondata = [
         [0, icon, (icon, 0, 0), top, mawbottom, -999.0, -999.0]
         for icon in range(nlay)
     ]
-    # <wellno> <mawsetting>
+    # <ifno> <mawsetting>
     mawperioddata = [[0, "STATUS", "ACTIVE"]]
     maw = flopy.mf6.ModflowGwfmaw(
         gwf,
@@ -185,19 +186,17 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # calculate volume of water and make sure it is conserved
-    gwfname = "gwf_" + sim.name
+    gwfname = "gwf_" + test.name
     fname = gwfname + ".maw.bin"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     bobj = flopy.utils.HeadFile(fname, text="HEAD")
     stage = bobj.get_alldata().flatten()
 
     fname = gwfname + ".hds"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     hobj = flopy.utils.HeadFile(fname)
     head = hobj.get_alldata()
@@ -214,7 +213,6 @@ def eval_results(sim):
     # calculate current volume of water in well and aquifer and compare with
     # initial volume
     for kstp, mawstage in enumerate(stage):
-
         vgwf = 0
         for k in range(nlay):
             for j in range(ncol):
@@ -229,13 +227,13 @@ def eval_results(sim):
     # compare the maw-gwf flows in maw budget file with the gwf-maw flows in
     # gwf budget file.  Values should be the same but reversed in sign
     fname = gwfname + ".maw.bud"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     mbud = flopy.utils.CellBudgetFile(fname, precision="double")
     maw_gwf = mbud.get_data(text="GWF")
 
     fname = gwfname + ".cbc"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     gbud = flopy.utils.CellBudgetFile(fname, precision="double")
     gwf_maw = gbud.get_data(text="MAW")
@@ -251,16 +249,13 @@ def eval_results(sim):
             assert np.allclose(qmaw, -qgwf), msg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, 0, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=0
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_buy_sfr01.py b/autotest/test_gwf_buy_sfr01.py
index 24f9bb12122..cf49f0d198b 100644
--- a/autotest/test_gwf_buy_sfr01.py
+++ b/autotest/test_gwf_buy_sfr01.py
@@ -1,19 +1,20 @@
-# Simple one-layer model with sfr on top.  Purpose is to test buy package in a
-# one-d sfr network.
+"""
+Simple one-layer model with sfr on top.  Purpose is to test buy package in a
+one-d sfr network.
+"""
 
 import os
-import sys
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["buy_sfr_01"]
+cases = ["buy_sfr_01"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     lx = 7.0
     lz = 1.0
     nlay = 1
@@ -44,10 +45,10 @@ def build_model(idx, dir):
     nouter, ninner = 700, 300
     hclose, rclose, relax = 1e-8, 1e-6, 0.97
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -372,16 +373,14 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # assign names
-    gwtname = "gwt_" + sim.name
-    gwfname = "gwf_" + sim.name
+    gwtname = "gwt_" + test.name
+    gwfname = "gwf_" + test.name
 
     # load the sft concentrations and make sure all values are correct
     fname = gwtname + ".sft.bin"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     cobj = flopy.utils.HeadFile(fname, text="CONCENTRATION")
     csftall = cobj.get_alldata()
@@ -391,21 +390,21 @@ def eval_results(sim):
 
     # load the aquifer concentrations
     fname = gwtname + ".ucn"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     cobj = flopy.utils.HeadFile(fname, text="CONCENTRATION")
     cgwfall = cobj.get_alldata()
     cgwf = cgwfall[-2].flatten()
 
     # load the aquifer heads
     fname = gwfname + ".hds"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     hobj = flopy.utils.HeadFile(fname, text="HEAD")
     headall = hobj.get_alldata()
     head = headall[-1].flatten()
 
     # load the sfr budget file and get sfr/gwf flows
     fname = gwfname + ".sfr.bud"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     bobj = flopy.utils.CellBudgetFile(fname, precision="double", verbose=False)
     qsfrgwfsimall = bobj.get_data(text="GWF")
@@ -415,7 +414,7 @@ def eval_results(sim):
     # load the sfr budget and check to make sure that concentrations are set
     # correctly from sft concentrations
     fname = gwfname + ".sfr.bud"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     bobj = flopy.utils.CellBudgetFile(fname, precision="double", verbose=False)
     b = bobj.get_data(text="AUXILIARY")
@@ -427,7 +426,7 @@ def eval_results(sim):
     # load the sfr stage file
     # load the aquifer concentrations and make sure all values are correct
     fname = gwfname + ".sfr.stg"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     stgobj = flopy.utils.HeadFile(fname, text="STAGE")
     stageall = stgobj.get_alldata()
     stage = stageall[-1]
@@ -457,13 +456,13 @@ def eval_results(sim):
         ), f"reach {n} flow {qcalc} not equal {qsim}"
 
 
-@pytest.mark.parametrize("name", ex)
-def test_mf6model(name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, 0, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=0
-        ),
-        str(function_tmpdir),
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_chd01.py b/autotest/test_gwf_chd01.py
index 0dabc3ac06d..0ee33dab664 100644
--- a/autotest/test_gwf_chd01.py
+++ b/autotest/test_gwf_chd01.py
@@ -3,15 +3,15 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = [
+cases = [
     "chd01",
 ]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 100
     nper = 1
     perlen = [5.0]
@@ -34,10 +34,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -118,12 +118,10 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
-    gwfname = "gwf_" + sim.name
+def check_output(idx, test):
+    gwfname = "gwf_" + test.name
 
-    fpth = os.path.join(sim.simpath, f"{gwfname}.hds")
+    fpth = os.path.join(test.workspace, f"{gwfname}.hds")
     hobj = flopy.utils.HeadFile(fpth, precision="double")
     head = hobj.get_data().flatten()
 
@@ -134,13 +132,13 @@ def eval_model(sim):
     ), "simulated head do not match with known solution."
 
 
-@pytest.mark.parametrize("name", ex)
-def test_mf6model(name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, 0, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=0
-        ),
-        str(function_tmpdir),
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_chd02.py b/autotest/test_gwf_chd02.py
index 019a00917d4..af30d11a1b1 100644
--- a/autotest/test_gwf_chd02.py
+++ b/autotest/test_gwf_chd02.py
@@ -4,18 +4,18 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = [
+cases = [
     "chd02",
 ]
 
 
-def build_model(idx, workspace):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
     nlay, nrow, ncol = 1, 1, 10
-    sim = flopy.mf6.MFSimulation(sim_ws=workspace, sim_name=name)
+    sim = flopy.mf6.MFSimulation(sim_ws=test.workspace, sim_name=name)
     flopy.mf6.ModflowTdis(sim)
     flopy.mf6.ModflowIms(sim, complexity="simple")
     gwf = flopy.mf6.ModflowGwf(sim, modelname=name, print_input=True)
@@ -38,8 +38,8 @@ def build_model(idx, workspace):
         strt=10.0,
     )
     chd_data = [
-        (0, 0, 0, 10.0, 1.0, 100.),
-        (0, 0, ncol - 1, 5.0, 0.0, 100.),
+        (0, 0, 0, 10.0, 1.0, 100.0),
+        (0, 0, ncol - 1, 5.0, 0.0, 100.0),
     ]
     chd_data = {
         0: {
@@ -63,12 +63,10 @@ def build_model(idx, workspace):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
 
-    fpth = os.path.join(sim.simpath, f"{name}.hds")
+    fpth = os.path.join(test.workspace, f"{name}.hds")
     hobj = flopy.utils.HeadFile(fpth, precision="double")
     head = hobj.get_data().flatten()
 
@@ -92,13 +90,13 @@ def eval_model(sim):
     ), "simulated head does not match with known solution."
 
 
-@pytest.mark.parametrize("name", ex)
-def test_mf6model(name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, 0, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=0
-        ),
-        str(function_tmpdir),
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_db01_nr.py b/autotest/test_gwf_csub_db01_nr.py
index 58b16e09d05..7f96b7707c0 100644
--- a/autotest/test_gwf_csub_db01_nr.py
+++ b/autotest/test_gwf_csub_db01_nr.py
@@ -3,10 +3,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = (
+cases = (
     "csub_db01a",
     "csub_db01b",
     "csub_db01c",
@@ -59,10 +59,10 @@
 nlay, nrow, ncol = 2, 1, 2
 nper = 3
 tsp0 = 1.0
-perlen = [tsp0] + [365.2500000 for i in range(nper - 1)]
-nstp = [1] + [200 for i in range(nper - 1)]
-tsmult = [1.0] + [1.0 for i in range(nper - 1)]
-steady = [True] + [False for i in range(nper - 1)]
+perlen = [tsp0] + [365.2500000 for _ in range(nper - 1)]
+nstp = [1] + [200 for _ in range(nper - 1)]
+tsmult = [1.0] + [1.0 for _ in range(nper - 1)]
+steady = [True] + [False for _ in range(nper - 1)]
 delr, delc = 1000.0, 1000.0
 top = 0.0
 botm = [-10.0, -20.0]
@@ -81,8 +81,8 @@
 hclose, rclose, relax = 1e-9, 1e-3, 1.0
 
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 # all cells are active
 ib = 1
@@ -106,12 +106,12 @@
 H0 = 0.0
 
 
-def build_model(idx, dir):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
     newton = newtons[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -323,18 +323,16 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_comp(sim):
-    print("evaluating compaction...")
-
+def check_output(idx, test):
     # MODFLOW 6 total compaction results
-    fpth = os.path.join(sim.simpath, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
         assert False, f'could not load data from "{fpth}"'
 
     # get results from listing file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
     budl = flopy.utils.Mf6ListBudget(fpth)
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
@@ -346,11 +344,11 @@ def eval_comp(sim):
     d = np.recarray(nbud, dtype=dtype)
     for key in bud_lst:
         d[key] = 0.0
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
     cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -363,13 +361,13 @@ def eval_comp(sim):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
     for idx, key in enumerate(bud_lst):
@@ -379,48 +377,41 @@ def eval_comp(sim):
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.bud.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.bud.cmp.out"
     )
-    f = open(fpth, "w")
-    for i in range(diff.shape[0]):
-        if i == 0:
-            line = f"{'TIME':>10s}"
-            for idx, key in enumerate(bud_lst):
-                line += f"{key + '_LST':>25s}"
-                line += f"{key + '_CBC':>25s}"
-                line += f"{key + '_DIF':>25s}"
+    with open(fpth, "w") as f:
+        for i in range(diff.shape[0]):
+            if i == 0:
+                line = f"{'TIME':>10s}"
+                for key in bud_lst:
+                    line += f"{key + '_LST':>25s}"
+                    line += f"{key + '_CBC':>25s}"
+                    line += f"{key + '_DIF':>25s}"
+                f.write(line + "\n")
+            line = f"{d['totim'][i]:10g}"
+            for ii, key in enumerate(bud_lst):
+                line += f"{d0[key][i]:25g}"
+                line += f"{d[key][i]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
-        line = f"{d['totim'][i]:10g}"
-        for idx, key in enumerate(bud_lst):
-            line += f"{d0[key][i]:25g}"
-            line += f"{d[key][i]:25g}"
-            line += f"{diff[i, idx]:25g}"
-        f.write(line + "\n")
-    f.close()
 
     if diffmax > budtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_comp,
-            htol=htol,
-            idxsim=idx,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
+        htol=htol,
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_dbgeo01.py b/autotest/test_gwf_csub_dbgeo01.py
index c899557c3a8..2f49d4299ac 100644
--- a/autotest/test_gwf_csub_dbgeo01.py
+++ b/autotest/test_gwf_csub_dbgeo01.py
@@ -3,10 +3,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["csub_dbgeo01a"]
+cases = ["csub_dbgeo01a"]
 ndcell = [19]
 strt = [0.0]
 chdh = [0]
@@ -130,13 +130,13 @@
 
 # temporal discretization
 nper = 1
-perlen = [1000.0 for i in range(nper)]
-nstp = [100 for i in range(nper)]
-tsmult = [1.05 for i in range(nper)]
-steady = [False for i in range(nper)]
+perlen = [1000.0 for _ in range(nper)]
+nstp = [100 for _ in range(nper)]
+tsmult = [1.05 for _ in range(nper)]
+steady = [False for _ in range(nper)]
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 hnoflo = 1e30
 hdry = -1e30
@@ -190,7 +190,7 @@ def calc_stress(sgm0, sgs0, h, bt):
     return geo, es
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     c6 = []
     for j in range(0, ncol, 2):
         c6.append([(0, 0, j), chdh[idx]])
@@ -199,10 +199,10 @@ def build_model(idx, dir):
     geo, es = calc_stress(sgm, sgs, strt[idx], botm)
     sub6 = [[0, (0, 0, 1), "delay", -1.0, thick, 1.0, cc, cr, theta, kv, 1.0]]
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -312,11 +312,9 @@ def build_model(idx, dir):
     return sim, mc
 
 
-def eval_sub(sim):
-    print("evaluating subsidence...")
-
+def check_output(idx, test):
     # MODFLOW 6 total compaction results
-    fpth = os.path.join(sim.simpath, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -333,36 +331,37 @@ def eval_sub(sim):
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.comp.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.comp.cmp.out"
     )
-    f = open(fpth, "w")
-    line = f"{'TOTIM':>15s}"
-    line += f" {'CSUB':>15s}"
-    line += f" {'MF':>15s}"
-    line += f" {'DIFF':>15s}"
-    f.write(line + "\n")
-    for i in range(diff.shape[0]):
-        line = f"{tc0[i]:15g}"
-        line += f" {tc['TCOMP'][i]:15g}"
-        line += f" {tc0[i]:15g}"
-        line += f" {diff[i]:15g}"
+    with open(fpth, "w") as f:
+        line = f"{'TOTIM':>15s}"
+        line += f" {'CSUB':>15s}"
+        line += f" {'MF':>15s}"
+        line += f" {'DIFF':>15s}"
         f.write(line + "\n")
-    f.close()
+        for i in range(diff.shape[0]):
+            line = f"{tc0[i]:15g}"
+            line += f" {tc['TCOMP'][i]:15g}"
+            line += f" {tc0[i]:15g}"
+            line += f" {diff[i]:15g}"
+            f.write(line + "\n")
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
-@pytest.mark.parametrize("name", ex)
-def test_mf6model(name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, 0, str(function_tmpdir))
-    test.run(
-        TestSimulation(name=name, exe_dict=targets, exfunc=eval_sub, idxsim=0),
-        str(function_tmpdir),
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_distypes.py b/autotest/test_gwf_csub_distypes.py
new file mode 100644
index 00000000000..dd29974a020
--- /dev/null
+++ b/autotest/test_gwf_csub_distypes.py
@@ -0,0 +1,435 @@
+import pathlib as pl
+
+import flopy
+import numpy as np
+import pytest
+from flopy.utils.gridgen import Gridgen
+
+from conftest import try_get_target
+from framework import TestFramework
+
+cases = ["csub_dis", "csub_disv", "csub_disu", "csub_disu01", "csub_disu02"]
+ex_dict = {name: None for name in cases}
+ex_dict["csub_disu01"] = 0
+ex_dict["csub_disu02"] = 2
+paktest = "csub"
+
+# temporal discretization
+nper = 2
+perlen = [1.0, 100.0]
+nstp = [1, 10]
+tsmult = [1.0] * nper
+tdis_rc = []
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
+
+# base spatial discretization
+nlay, nrow, ncol = 3, 9, 9
+refinement_level = 2
+nrow_refined, ncol_refined = nrow * refinement_level, ncol * refinement_level
+shape3d = (nlay, nrow, ncol)
+shape3d_refined = (nlay, nrow_refined, ncol_refined)
+shape2d = (nrow, ncol)
+shape2d_refined = (nrow_refined, ncol_refined)
+size3d = nlay * nrow * ncol
+size3d_refined = nlay * nrow_refined * ncol_refined
+size2d = nrow * ncol
+size2d_refined = nrow_refined * ncol_refined
+
+delr = delc = 1000.0
+top = 0.0
+bot = -100.0
+dz = (top - bot) / nlay
+botm = [top - k * dz for k in range(1, nlay + 1)]
+z_node = [z + 0.5 * dz for z in botm]
+
+delr_refined = delr / refinement_level
+delc_refined = delc / refinement_level
+
+hk = [1.0, 0.001, 1.0]
+sy = [0.25, 0.45, 0.25]
+ss = [5e-5, 5e-4, 5e-5]
+
+well_coordinates = (
+    np.array([(4.25, 4.25), (4.25, 4.75), (4.75, 4.75), (4.75, 4.25)]) * delr
+)
+wellq = -1000.0
+
+nouter, ninner = 100, 300
+dvclose, rclose, relax = 1e-6, 0.01, 0.97
+
+# subwt data
+cc = 0.25
+cr = 0.25
+void = 0.82
+theta = void / (1.0 + void)
+kv = 999.0
+sgm = 1.7
+sgs = 2.0
+
+beta = 0.0
+# beta = 4.65120000e-10
+gammaw = 9806.65000000
+
+
+def get_interbed(modelgrid):
+    grid_type = modelgrid.grid_type
+    ia = []
+    x0, x1, y0, y1 = modelgrid.extent
+    for k in range(1, nlay, 1):
+        cellid = modelgrid.intersect(x0 + 0.1, y1 - 0.1, z=z_node[k])
+        ia.append(get_node_number(modelgrid, cellid))
+
+    package_data = []
+    ifno = 0
+    ini_stress = 0.0
+
+    nodes = [node for node in range(ia[0], ia[1])]
+    if grid_type == "structured":
+        cellids = modelgrid.get_lrc(nodes)
+    elif grid_type == "vertex":
+        cellids = modelgrid.get_lni(nodes)
+    else:
+        cellids = [(node,) for node in nodes]
+
+    for cellid in cellids:
+        rnb = 1.0
+        vk = 999.0
+        package_data.append(
+            (
+                ifno,
+                cellid,  # will need to be detuplaized with *cellid - does not work for dis
+                "nodelay",
+                ini_stress,
+                modelgrid.cell_thickness[cellid],
+                rnb,
+                ss[1],
+                ss[1] * 1000.0,
+                theta,
+                vk,
+                top,
+            )
+        )
+        ifno += 1
+    return package_data
+
+
+def build_dis(gwf):
+    return flopy.mf6.ModflowGwfdis(
+        gwf,
+        nlay=nlay,
+        nrow=nrow,
+        ncol=ncol,
+        delr=delr,
+        delc=delc,
+        top=top,
+        botm=botm,
+    )
+
+
+def get_gridgen_ws(ws):
+    gridgen_ws = ws / "gridgen"
+    gridgen_ws.mkdir(parents=True, exist_ok=True)
+    return gridgen_ws
+
+
+def build_temp_gwf(ws):
+    gridgen_ws = get_gridgen_ws(ws)
+    gridgen_sim = flopy.mf6.MFSimulation(
+        sim_name="gridgen", sim_ws=gridgen_ws, exe_name="mf6"
+    )
+    gridgen_gwf = flopy.mf6.ModflowGwf(gridgen_sim, modelname="gridgen")
+    return gridgen_gwf
+
+
+def build_disv(ws, gwf, gridgen):
+    temp_gwf = build_temp_gwf(ws)
+    dis = build_dis(temp_gwf)
+    g = Gridgen(
+        temp_gwf.modelgrid,
+        model_ws=get_gridgen_ws(ws),
+        exe_name=gridgen,
+    )
+    g.build()
+    gridprops = g.get_gridprops_disv()
+    return flopy.mf6.ModflowGwfdisv(gwf, **gridprops)
+
+
+def build_disu(ws, gwf, refinement_layer, gridgen):
+    temp_gwf = build_temp_gwf(ws)
+    dis = build_dis(temp_gwf)
+    g = Gridgen(
+        temp_gwf.modelgrid,
+        model_ws=get_gridgen_ws(ws),
+        exe_name=gridgen,
+    )
+    if refinement_layer is not None:
+        x0, x1, y0, y1 = temp_gwf.modelgrid.extent
+        polys = [[[(x0, y0), (x1, y0), (x1, y1), (x0, y1), (x0, y0)]]]
+        g.add_refinement_features(
+            polys,
+            "polygon",
+            1,
+            layers=[refinement_layer],
+        )
+    g.build()
+    gridprops = g.get_gridprops_disu6()
+    return flopy.mf6.ModflowGwfdisu(gwf, **gridprops)
+
+
+def get_node_number(modelgrid, cellid):
+    if modelgrid.grid_type == "unstructured":
+        node = cellid
+    elif modelgrid.grid_type == "vertex":
+        node = modelgrid.ncpl * cellid[0] + cellid[1]
+    else:
+        node = (
+            modelgrid.nrow * modelgrid.ncol * cellid[0]
+            + modelgrid.ncol * cellid[1]
+            + cellid[2]
+        )
+    return node
+
+
+def build_3d_array(modelgrid, values, dtype=float):
+    if isinstance(values, dtype):
+        arr = np.full(modelgrid.nnodes, values, dtype=dtype)
+    else:
+        arr = np.zeros(modelgrid.nnodes, dtype=dtype)
+        ia = []
+        x0, x1, y0, y1 = modelgrid.extent
+        for k in range(nlay):
+            cellid = modelgrid.intersect(x0 + 0.1, y1 - 0.1, z=z_node[k])
+            ia.append(get_node_number(modelgrid, cellid))
+        ia.append(modelgrid.nnodes + 1)
+        for k in range(nlay):
+            arr[ia[k] : ia[k + 1]] = values[k]
+    return arr.reshape(modelgrid.shape)
+
+
+def build_well_data(modelgrid):
+    well_spd = []
+    for x, y in well_coordinates:
+        cellid = modelgrid.intersect(x, y, z=z_node[-1])
+        if isinstance(cellid, tuple):
+            well_spd.append((*cellid, wellq))
+        else:
+            well_spd.append((cellid, wellq))
+    return {1: well_spd}
+
+
+def build_models(idx, test):
+    gridgen = try_get_target(test.targets, "gridgen")
+    return build_mf6(idx, test.workspace, gridgen), None
+
+
+# build MODFLOW 6 files
+def build_mf6(idx, ws, gridgen):
+    name = cases[idx]
+    sim = flopy.mf6.MFSimulation(
+        sim_name=name,
+        version="mf6",
+        exe_name="mf6",
+        sim_ws=ws,
+    )
+    # create tdis package
+    tdis = flopy.mf6.ModflowTdis(
+        sim,
+        time_units="DAYS",
+        nper=nper,
+        perioddata=tdis_rc,
+    )
+
+    # create iterative model solution and register the gwf model with it
+    ims = flopy.mf6.ModflowIms(
+        sim,
+        print_option="SUMMARY",
+        outer_dvclose=dvclose,
+        outer_maximum=nouter,
+        under_relaxation="NONE",
+        inner_maximum=ninner,
+        inner_dvclose=dvclose,
+        rcloserecord=rclose,
+        linear_acceleration="CG",
+        scaling_method="NONE",
+        reordering_method="NONE",
+        relaxation_factor=relax,
+    )
+
+    # create gwf model
+    gwf = flopy.mf6.ModflowGwf(
+        sim,
+        modelname=name,
+        print_input=True,
+        save_flows=True,
+    )
+
+    if "disv" in name:
+        dis = build_disv(ws, gwf, gridgen)
+    elif "disu" in name:
+        dis = build_disu(ws, gwf, ex_dict[name], gridgen)
+    else:
+        dis = build_dis(gwf)
+
+    # initial conditions
+    ic = flopy.mf6.ModflowGwfic(
+        gwf,
+        strt=top,
+    )
+
+    k11 = build_3d_array(gwf.modelgrid, hk)
+    icelltype = build_3d_array(gwf.modelgrid, [1, 0, 0], dtype=int)
+
+    # node property flow
+    npf = flopy.mf6.ModflowGwfnpf(
+        gwf,
+        icelltype=icelltype,
+        k=k11,
+        k33=k11,
+    )
+
+    # storage
+    sy_arr = build_3d_array(gwf.modelgrid, sy)
+    sto = flopy.mf6.ModflowGwfsto(
+        gwf,
+        iconvert=icelltype,
+        ss=0.0,
+        sy=sy_arr,
+        transient={0: True},
+    )
+
+    # well
+    wel = flopy.mf6.ModflowGwfwel(
+        gwf,
+        stress_period_data=build_well_data(gwf.modelgrid),
+        save_flows=False,
+    )
+
+    # csub
+    cg_ske_cr = build_3d_array(gwf.modelgrid, ss)
+    packagedata = get_interbed(gwf.modelgrid)
+
+    csub = flopy.mf6.ModflowGwfcsub(
+        gwf,
+        zdisplacement_filerecord=f"{name}.csub.zdis.bin",
+        compaction_filerecord=f"{name}.csub.comp.bin",
+        ninterbeds=len(packagedata),
+        sgs=sgs,
+        sgm=sgm,
+        beta=beta,
+        gammaw=gammaw,
+        cg_ske_cr=cg_ske_cr,
+        cg_theta=theta,
+        packagedata=packagedata,
+    )
+    # orecarray = {}
+    # orecarray["csub_obs.csv"] = [
+    #     ("wc01", "compaction-cell", (1, 5, 8)),
+    #     ("wc02", "compaction-cell", (3, 6, 11)),
+    # ]
+    # csub_obs_package = csub.obs.initialize(
+    #     filename=opth, digits=10, print_input=True, continuous=orecarray
+    # )
+
+    # output control
+    oc = flopy.mf6.ModflowGwfoc(
+        gwf,
+        budget_filerecord=f"{name}.cbc",
+        head_filerecord=f"{name}.hds",
+        headprintrecord=[("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")],
+        saverecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
+        printrecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
+    )
+    return sim
+
+
+def check_output(idx, test):
+    name = cases[idx]
+    ws = pl.Path(test.workspace)
+    test = flopy.mf6.MFSimulation.load(sim_name=name, sim_ws=ws)
+    gwf = test.get_model()
+    x0, x1, y0, y1 = gwf.modelgrid.extent
+
+    comp_obj = flopy.utils.HeadFile(
+        ws / f"{name}.csub.comp.bin",
+        text="CSUB-COMPACTION",
+        precision="double",
+    )
+    zdis_obj = flopy.utils.HeadFile(
+        ws / f"{name}.csub.zdis.bin",
+        text="CSUB-ZDISPLACE",
+        precision="double",
+    )
+
+    layer_refinement = ex_dict[name]
+
+    # create reusable mapping dictionary so it can be used for all time step
+    # with refined disu grids - which do not have naturally ordered node
+    # numbers in refined layers
+    map_dict = {}
+    if layer_refinement is not None:
+        z = z_node[layer_refinement]
+        icnt = 0
+        for i in range(nrow_refined):
+            y = y1 - delc_refined * (i + 0.5)
+            for j in range(ncol_refined):
+                x = x0 + delr_refined * (j + 0.5)
+                node = gwf.modelgrid.intersect(x, y, z=z)
+                map_dict[icnt] = {"node": node, "cellid": (i, j)}
+                icnt += 1
+
+    for totim in comp_obj.get_times():
+        if layer_refinement is None:
+            comp = comp_obj.get_data(totim=totim).flatten().reshape(shape3d)
+            zdis = zdis_obj.get_data(totim=totim).flatten().reshape(shape3d)
+        else:
+            comp1d = comp_obj.get_data(totim=totim).squeeze()
+            zdis1d = zdis_obj.get_data(totim=totim).squeeze()
+            ia = [0]
+            for k in range(nlay):
+                if k == layer_refinement:
+                    ia.append(ia[k] + size2d_refined)
+                else:
+                    ia.append(ia[k] + size2d)
+
+            comp = np.zeros(shape3d, dtype=float)
+            zdis = np.zeros(shape3d, dtype=float)
+            for k in range(nlay):
+                ia0 = ia[k]
+                ia1 = ia[k + 1]
+                comp_slice = comp1d[ia0:ia1].copy()
+                zdis_slice = zdis1d[ia0:ia1].copy()
+                if k == layer_refinement:
+                    comp_temp = np.zeros(shape2d_refined, dtype=float)
+                    zdis_temp = np.zeros(shape2d_refined, dtype=float)
+                    for value in map_dict.values():
+                        comp_temp[value["cellid"]] = comp1d[value["node"]]
+                        zdis_temp[value["cellid"]] = zdis1d[value["node"]]
+                    comp[k] = comp_temp.reshape(
+                        nrow_refined // 2, 2, ncol_refined // 2, 2
+                    ).mean(axis=(1, -1))
+                    zdis[k] = zdis_temp.reshape(
+                        nrow_refined // 2, 2, ncol_refined // 2, 2
+                    ).mean(axis=(1, -1))
+                else:
+                    comp[k] = comp_slice.reshape(shape2d)
+                    zdis[k] = zdis_slice.reshape(shape2d)
+
+        comp = comp.sum(axis=0)
+        zdis = zdis[0]
+        assert np.allclose(comp, zdis), (
+            "sum of compaction is not equal to the "
+            + f"z-displacement at time {totim}"
+        )
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
+    )
+    test.run()
diff --git a/autotest/test_gwf_csub_inelastic.py b/autotest/test_gwf_csub_inelastic.py
index 9d4e40575b7..dd5546092f2 100644
--- a/autotest/test_gwf_csub_inelastic.py
+++ b/autotest/test_gwf_csub_inelastic.py
@@ -3,12 +3,12 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
 paktest = "csub"
 budtol = 1e-2
-ex = ["csub_de01a"]
+cases = ["csub_de01a"]
 
 # static model data
 # spatial discretization
@@ -75,7 +75,7 @@
 
 
 def build_mf6(idx, ws, update=None):
-    name = ex[idx]
+    name = cases[idx]
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -185,16 +185,10 @@ def build_mf6(idx, ws, update=None):
     return sim
 
 
-def build_model(idx, dir):
-    name = ex[idx]
-    ws = dir
-
-    # build MODFLOW 6 files
-    sim = build_mf6(idx, ws)
-
-    ws = os.path.join(dir, "mf6")
-    mc = build_mf6(idx, ws, update=True)
-
+def build_models(idx, test):
+    name = cases[idx]
+    sim = build_mf6(idx, test.workspace)
+    mc = build_mf6(idx, os.path.join(test.workspace, "mf6"), update=True)
     return sim, mc
 
 
@@ -208,13 +202,11 @@ def calc_void(theta):
     return theta / (1.0 - theta)
 
 
-def eval_void(sim):
-    print("evaluating void ratio...")
-
-    fpth = os.path.join(sim.simpath, "csub_obs.csv")
+def check_output(idx, test):
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
     cd = np.genfromtxt(fpth, delimiter=",", names=True)
 
-    fpth = os.path.join(sim.simpath, "mf6", "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "mf6", "csub_obs.csv")
     cd2 = np.genfromtxt(fpth, delimiter=",", names=True)
 
     v = calc_comp2void(cd["COMP"])
@@ -228,42 +220,38 @@ def eval_void(sim):
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.comp.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.comp.cmp.out"
     )
-    f = open(fpth, "w")
-    line = f"{'TOTIM':>15s}"
-    line += f" {'VOID':>15s}"
-    line += f" {'MF':>15s}"
-    line += f" {'DIFF':>15s}"
-    f.write(line + "\n")
-    for i in range(diff.shape[0]):
-        line = f"{cd['time'][i]:15g}"
-        line += f" {v[i]:15g}"
-        line += f" {v[i]:15g}"
-        line += f" {diff[i]:15g}"
+    with open(fpth, "w") as f:
+        line = f"{'TOTIM':>15s}"
+        line += f" {'VOID':>15s}"
+        line += f" {'MF':>15s}"
+        line += f" {'DIFF':>15s}"
         f.write(line + "\n")
-    f.close()
+        for i in range(diff.shape[0]):
+            line = f"{cd['time'][i]:15g}"
+            line += f" {v[i]:15g}"
+            line += f" {v[i]:15g}"
+            line += f" {diff[i]:15g}"
+            f.write(line + "\n")
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_void, idxsim=idx
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_ndb01_nr.py b/autotest/test_gwf_csub_ndb01_nr.py
index 0360ca612ea..8923da61787 100644
--- a/autotest/test_gwf_csub_ndb01_nr.py
+++ b/autotest/test_gwf_csub_ndb01_nr.py
@@ -3,11 +3,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from modflow_devtools.misc import is_in_ci
-from simulation import TestSimulation
 
-ex = (
+cases = (
     "csub_ndb01a",
     "csub_ndb01b",
     "csub_ndb01c",
@@ -60,10 +59,10 @@
 nlay, nrow, ncol = 2, 1, 2
 nper = 3
 tsp0 = 1.0
-perlen = [tsp0] + [365.2500000 for i in range(nper - 1)]
-nstp = [1] + [200 for i in range(nper - 1)]
-tsmult = [1.0] + [1.0 for i in range(nper - 1)]
-steady = [True] + [False for i in range(nper - 1)]
+perlen = [tsp0] + [365.2500000 for _ in range(nper - 1)]
+nstp = [1] + [200 for _ in range(nper - 1)]
+tsmult = [1.0] + [1.0 for _ in range(nper - 1)]
+steady = [True] + [False for _ in range(nper - 1)]
 delr, delc = 1000.0, 1000.0
 top = 0.0
 botm = [-10.0, -20.0]
@@ -82,8 +81,8 @@
 hclose, rclose, relax = 1e-9, 1e-3, 1.0
 
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 # all cells are active
 ib = 1
@@ -107,12 +106,12 @@
 H0 = 0.0
 
 
-def build_model(idx, dir):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
     newton = newtons[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -296,18 +295,16 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_comp(sim):
-    print("evaluating compaction...")
-
+def check_output(idx, test):
     # MODFLOW 6 total compaction results
-    fpth = os.path.join(sim.simpath, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
         assert False, f'could not load data from "{fpth}"'
 
     # get results from listing file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
     budl = flopy.utils.Mf6ListBudget(fpth)
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
@@ -319,11 +316,11 @@ def eval_comp(sim):
     d = np.recarray(nbud, dtype=dtype)
     for key in bud_lst:
         d[key] = 0.0
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
     cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -336,64 +333,57 @@ def eval_comp(sim):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, key in enumerate(bud_lst):
-        diff[:, idx] = d0[key] - d[key]
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
     diffmax = np.abs(diff).max()
     msg = f"maximum absolute total-budget difference ({diffmax}) "
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.bud.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.bud.cmp.out"
     )
-    f = open(fpth, "w")
-    for i in range(diff.shape[0]):
-        if i == 0:
-            line = f"{'TIME':>10s}"
-            for idx, key in enumerate(bud_lst):
-                line += f"{key + '_LST':>25s}"
-                line += f"{key + '_CBC':>25s}"
-                line += f"{key + '_DIF':>25s}"
+    with open(fpth, "w") as f:
+        for i in range(diff.shape[0]):
+            if i == 0:
+                line = f"{'TIME':>10s}"
+                for key in bud_lst:
+                    line += f"{key + '_LST':>25s}"
+                    line += f"{key + '_CBC':>25s}"
+                    line += f"{key + '_DIF':>25s}"
+                f.write(line + "\n")
+            line = f"{d['totim'][i]:10g}"
+            for ii, key in enumerate(bud_lst):
+                line += f"{d0[key][i]:25g}"
+                line += f"{d[key][i]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
-        line = f"{d['totim'][i]:10g}"
-        for idx, key in enumerate(bud_lst):
-            line += f"{d0[key][i]:25g}"
-            line += f"{d[key][i]:25g}"
-            line += f"{diff[i, idx]:25g}"
-        f.write(line + "\n")
-    f.close()
 
     if diffmax > budtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_comp,
-            htol=htol,
-            idxsim=idx,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
+        htol=htol,
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_sk01.py b/autotest/test_gwf_csub_sk01.py
index ed222a07720..9d993088617 100644
--- a/autotest/test_gwf_csub_sk01.py
+++ b/autotest/test_gwf_csub_sk01.py
@@ -1,488 +1,461 @@
 import os
-from typing import List, NamedTuple
 
 import flopy
 import numpy as np
+import pytest
+
 from framework import TestFramework
-from pytest_cases import parametrize, parametrize_with_cases
-from simulation import TestSimulation
-
-
-class GwfCsubSkCases:
-    dtol: float = 1e-3
-    budtol: float = 0.01
-    bud_lst: List[str] = [
-        "CSUB-CGELASTIC_IN",
-        "CSUB-CGELASTIC_OUT",
-        "CSUB-WATERCOMP_IN",
-        "CSUB-WATERCOMP_OUT",
+
+simname = "gwfcsubsk01"
+cases = [f"{simname}a", f"{simname}b", f"{simname}c"]
+dtol = 1e-3
+budtol = 0.01
+bud_lst = [
+    "CSUB-CGELASTIC_IN",
+    "CSUB-CGELASTIC_OUT",
+    "CSUB-WATERCOMP_IN",
+    "CSUB-WATERCOMP_OUT",
+]
+cvopt = [None, None, None]
+constantcv = [True, True, True]
+ndelaybeds = [0, 0, 0]
+top = [0, 0, 15]
+newton = [False, True, True]
+htol = [None, None, 0.3]
+
+
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace)
+    cmp = get_model(idx, test.workspace / "mf6_regression")
+    return sim, cmp
+
+
+def get_model(idx, workspace):
+    name = cases[idx]
+    newtonoptions = None
+    imsla = "CG"
+    if newton[idx]:
+        newtonoptions = "NEWTON"
+        imsla = "BICGSTAB"
+
+    # static model data
+    nlay, nrow, ncol = 3, 10, 10
+    nper = 31
+    perlen = [1.0] + [365.2500000 for i in range(nper - 1)]
+    nstp = [1] + [6 for i in range(nper - 1)]
+    tsmult = [1.0] + [1.3 for i in range(nper - 1)]
+    steady = [True] + [False for i in range(nper - 1)]
+    delr, delc = 1000.0, 2000.0
+    botm = [-100, -150.0, -350.0]
+    zthick = [top[idx] - botm[0], botm[0] - botm[1], botm[1] - botm[2]]
+    strt = 100.0
+    hnoflo = 1e30
+    hdry = -1e30
+
+    # calculate hk
+    hk1fact = 1.0 / zthick[1]
+    hk1 = np.ones((nrow, ncol), dtype=float) * 0.5 * hk1fact
+    hk1[0, :] = 1000.0 * hk1fact
+    hk1[-1, :] = 1000.0 * hk1fact
+    hk1[:, 0] = 1000.0 * hk1fact
+    hk1[:, -1] = 1000.0 * hk1fact
+    hk = [20.0, hk1, 5.0]
+
+    # calculate vka
+    vka = [1e6, 7.5e-5, 1e6]
+
+    # set rest of npf variables
+    laytyp = [1, 0, 0]
+    laytypu = [4, 0, 0]
+    sy = 0.0  # [0.1, 0., 0.]
+
+    nouter, ninner = 500, 300
+    hclose, rclose, relax = 1e-9, 1e-6, 1.0
+
+    tdis_rc = []
+    for i in range(nper):
+        tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
+
+    # all cells are active
+    ib = 1
+
+    # chd data
+    c = []
+    c6 = []
+    ccol = [3, 4, 5, 6]
+    for j in ccol:
+        c.append([0, nrow - 1, j, strt, strt])
+        c6.append([(0, nrow - 1, j), strt])
+    cd = {0: c}
+    cd6 = {0: c6}
+    maxchd = len(cd[0])
+
+    # pumping well data
+    wr = [0, 0, 0, 0, 1, 1, 2, 2, 3, 3]
+    wc = [0, 1, 8, 9, 0, 9, 0, 9, 0, 0]
+    wrp = [2, 2, 3, 3]
+    wcp = [5, 6, 5, 6]
+    wq = [-14000.0, -8000.0, -5000.0, -3000.0]
+    d = []
+    d6 = []
+    for r, c, q in zip(wrp, wcp, wq):
+        d.append([2, r, c, q])
+        d6.append([(2, r, c), q])
+    wd = {1: d}
+    wd6 = {1: d6}
+    maxwel = len(wd[1])
+
+    # recharge data
+    q = 3000.0 / (delr * delc)
+    v = np.zeros((nrow, ncol), dtype=float)
+    for r, c in zip(wr, wc):
+        v[r, c] = q
+    rech = {0: v}
+
+    # static ibc and sub data
+    sgm = 0.0
+    sgs = 0.0
+    omega = 1.0
+    void = 0.82
+    theta = void / (1.0 + void)
+    sw = 4.65120000e-10 * 9806.65000000 * theta
+
+    # no delay bed data
+    nndb = 3
+    lnd = [0, 1, 2]
+    hc = [botm[-1] for k in range(nlay)]
+    thicknd0 = [zthick[0], zthick[1], zthick[2]]
+    ccnd0 = [6e-6, 3e-6, 6e-6]
+    crnd0 = [6e-6, 3e-6, 6e-6]
+    sfv = []
+    sfe = []
+    for k in range(nlay):
+        sfv.append(ccnd0[k] * thicknd0[k])
+        sfe.append(crnd0[k] * thicknd0[k])
+
+    # sub output data
+    ds15 = [0, 0, 0, 2052, 0, 0, 0, 0, 0, 0, 0, 0]
+    ds16 = [
+        0,
+        nper - 1,
+        0,
+        nstp[-1] - 1,
+        0,
+        0,
+        1,
+        1,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        1,
     ]
 
-    class Data(NamedTuple):
-        name: str
-        cvopt: str
-        constantcv: bool
-        ndelaybeds: int
-        top: float
-        newton: bool
-        htol: float
-
-    @parametrize(
-        data=[
-            Data("a", None, True, 0, 0, False, None),
-            Data("b", None, True, 0, 0, True, None),
-            Data("c", None, True, 0, 15, True, 0.3),
-        ]
+    # build MODFLOW 6 files
+    sim = flopy.mf6.MFSimulation(
+        sim_name=name,
+        version="mf6",
+        exe_name="mf6",
+        sim_ws=str(workspace),
+    )
+    # create tdis package
+    tdis = flopy.mf6.ModflowTdis(
+        sim, time_units="DAYS", nper=nper, perioddata=tdis_rc
+    )
+
+    # create iterative model solution
+    ims = flopy.mf6.ModflowIms(
+        sim,
+        print_option="SUMMARY",
+        outer_dvclose=hclose,
+        outer_maximum=nouter,
+        under_relaxation="NONE",
+        inner_maximum=ninner,
+        inner_dvclose=hclose,
+        rcloserecord=rclose,
+        linear_acceleration=imsla,
+        scaling_method="NONE",
+        reordering_method="NONE",
+        relaxation_factor=relax,
+    )
+
+    # create gwf model
+    gwf = flopy.mf6.ModflowGwf(
+        sim, modelname=name, newtonoptions=newtonoptions
+    )
+
+    dis = flopy.mf6.ModflowGwfdis(
+        gwf,
+        nlay=nlay,
+        nrow=nrow,
+        ncol=ncol,
+        delr=delr,
+        delc=delc,
+        top=top[idx],
+        botm=botm,
+        filename=f"{name}.dis",
+    )
+
+    # initial conditions
+    ic = flopy.mf6.ModflowGwfic(gwf, strt=strt, filename=f"{name}.ic")
+
+    # node property flow
+    npf = flopy.mf6.ModflowGwfnpf(
+        gwf,
+        save_flows=False,
+        # dev_modflowusg_upstream_weighted_saturation=True,
+        icelltype=laytyp,
+        cvoptions=cvopt[idx],
+        k=hk,
+        k33=vka,
+    )
+    # storage
+    sto = flopy.mf6.ModflowGwfsto(
+        gwf,
+        save_flows=False,
+        iconvert=laytyp,
+        ss=0.0,
+        sy=sy,
+        storagecoefficient=True,
+        steady_state={0: True},
+        transient={1: True},
+    )
+
+    # recharge
+    rch = flopy.mf6.ModflowGwfrcha(gwf, readasarrays=True, recharge=rech)
+
+    # wel file
+    wel = flopy.mf6.ModflowGwfwel(
+        gwf,
+        print_input=True,
+        print_flows=True,
+        maxbound=maxwel,
+        stress_period_data=wd6,
+        save_flows=False,
+    )
+
+    # chd files
+    chd = flopy.mf6.modflow.mfgwfchd.ModflowGwfchd(
+        gwf, maxbound=maxchd, stress_period_data=cd6, save_flows=False
+    )
+    # csub files
+    opth = f"{name}.csub.obs"
+    csub = flopy.mf6.ModflowGwfcsub(
+        gwf,
+        head_based=True,
+        save_flows=True,
+        ninterbeds=0,
+        cg_theta=theta,
+        cg_ske_cr=crnd0,
+        packagedata=None,
     )
-    def case_generator(self, function_tmpdir, data):
-        sim = self.get_model(data, function_tmpdir)
-        cmp = self.get_model(data, function_tmpdir / "mf6_regression")
-        return data, sim, cmp, self.eval_case
-
-    def get_model(self, data, function_tmpdir):
-        name = data.name
-        newton = data.newton
-        newtonoptions = None
-        imsla = "CG"
-        if newton:
-            newtonoptions = "NEWTON"
-            imsla = "BICGSTAB"
-
-        # static model data
-        nlay, nrow, ncol = 3, 10, 10
-        nper = 31
-        perlen = [1.0] + [365.2500000 for i in range(nper - 1)]
-        nstp = [1] + [6 for i in range(nper - 1)]
-        tsmult = [1.0] + [1.3 for i in range(nper - 1)]
-        steady = [True] + [False for i in range(nper - 1)]
-        delr, delc = 1000.0, 2000.0
-        top = 0.0
-        botm = [-100, -150.0, -350.0]
-        zthick = [top - botm[0], botm[0] - botm[1], botm[1] - botm[2]]
-        strt = 100.0
-        hnoflo = 1e30
-        hdry = -1e30
-
-        # calculate hk
-        hk1fact = 1.0 / zthick[1]
-        hk1 = np.ones((nrow, ncol), dtype=float) * 0.5 * hk1fact
-        hk1[0, :] = 1000.0 * hk1fact
-        hk1[-1, :] = 1000.0 * hk1fact
-        hk1[:, 0] = 1000.0 * hk1fact
-        hk1[:, -1] = 1000.0 * hk1fact
-        hk = [20.0, hk1, 5.0]
-
-        # calculate vka
-        vka = [1e6, 7.5e-5, 1e6]
-
-        # set rest of npf variables
-        laytyp = [1, 0, 0]
-        laytypu = [4, 0, 0]
-        sy = 0.0  # [0.1, 0., 0.]
-
-        nouter, ninner = 500, 300
-        hclose, rclose, relax = 1e-9, 1e-6, 1.0
-
-        tdis_rc = []
-        for idx in range(nper):
-            tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
-
-        # all cells are active
-        ib = 1
-
-        # chd data
-        c = []
-        c6 = []
-        ccol = [3, 4, 5, 6]
-        for j in ccol:
-            c.append([0, nrow - 1, j, strt, strt])
-            c6.append([(0, nrow - 1, j), strt])
-        cd = {0: c}
-        cd6 = {0: c6}
-        maxchd = len(cd[0])
-
-        # pumping well data
-        wr = [0, 0, 0, 0, 1, 1, 2, 2, 3, 3]
-        wc = [0, 1, 8, 9, 0, 9, 0, 9, 0, 0]
-        wrp = [2, 2, 3, 3]
-        wcp = [5, 6, 5, 6]
-        wq = [-14000.0, -8000.0, -5000.0, -3000.0]
-        d = []
-        d6 = []
-        for r, c, q in zip(wrp, wcp, wq):
-            d.append([2, r, c, q])
-            d6.append([(2, r, c), q])
-        wd = {1: d}
-        wd6 = {1: d6}
-        maxwel = len(wd[1])
-
-        # recharge data
-        q = 3000.0 / (delr * delc)
-        v = np.zeros((nrow, ncol), dtype=float)
-        for r, c in zip(wr, wc):
-            v[r, c] = q
-        rech = {0: v}
-
-        # static ibc and sub data
-        sgm = 0.0
-        sgs = 0.0
-        omega = 1.0
-        void = 0.82
-        theta = void / (1.0 + void)
-        sw = 4.65120000e-10 * 9806.65000000 * theta
-
-        # no delay bed data
-        nndb = 3
-        lnd = [0, 1, 2]
-        hc = [botm[-1] for k in range(nlay)]
-        thicknd0 = [zthick[0], zthick[1], zthick[2]]
-        ccnd0 = [6e-6, 3e-6, 6e-6]
-        crnd0 = [6e-6, 3e-6, 6e-6]
-        sfv = []
-        sfe = []
-        for k in range(nlay):
-            sfv.append(ccnd0[k] * thicknd0[k])
-            sfe.append(crnd0[k] * thicknd0[k])
-
-        # sub output data
-        ds15 = [0, 0, 0, 2052, 0, 0, 0, 0, 0, 0, 0, 0]
-        ds16 = [
-            0,
-            nper - 1,
-            0,
-            nstp[-1] - 1,
-            0,
-            0,
-            1,
-            1,
-            0,
-            0,
-            0,
-            0,
-            0,
-            0,
-            0,
-            0,
-            1,
-        ]
-
-        # build MODFLOW 6 files
-        sim = flopy.mf6.MFSimulation(
-            sim_name=name,
-            version="mf6",
-            exe_name="mf6",
-            sim_ws=str(function_tmpdir),
-        )
-        # create tdis package
-        tdis = flopy.mf6.ModflowTdis(
-            sim, time_units="DAYS", nper=nper, perioddata=tdis_rc
-        )
-
-        # create iterative model solution
-        ims = flopy.mf6.ModflowIms(
-            sim,
-            print_option="SUMMARY",
-            outer_dvclose=hclose,
-            outer_maximum=nouter,
-            under_relaxation="NONE",
-            inner_maximum=ninner,
-            inner_dvclose=hclose,
-            rcloserecord=rclose,
-            linear_acceleration=imsla,
-            scaling_method="NONE",
-            reordering_method="NONE",
-            relaxation_factor=relax,
-        )
-
-        # create gwf model
-        gwf = flopy.mf6.ModflowGwf(
-            sim, modelname=name, newtonoptions=newtonoptions
-        )
-
-        dis = flopy.mf6.ModflowGwfdis(
-            gwf,
-            nlay=nlay,
-            nrow=nrow,
-            ncol=ncol,
-            delr=delr,
-            delc=delc,
-            top=data.top,
-            botm=botm,
-            filename=f"{name}.dis",
-        )
-
-        # initial conditions
-        ic = flopy.mf6.ModflowGwfic(gwf, strt=strt, filename=f"{name}.ic")
-
-        # node property flow
-        npf = flopy.mf6.ModflowGwfnpf(
-            gwf,
-            save_flows=False,
-            # dev_modflowusg_upstream_weighted_saturation=True,
-            icelltype=laytyp,
-            cvoptions=data.cvopt,
-            k=hk,
-            k33=vka,
-        )
-        # storage
-        sto = flopy.mf6.ModflowGwfsto(
-            gwf,
-            save_flows=False,
-            iconvert=laytyp,
-            ss=0.0,
-            sy=sy,
-            storagecoefficient=True,
-            steady_state={0: True},
-            transient={1: True},
-        )
-
-        # recharge
-        rch = flopy.mf6.ModflowGwfrcha(gwf, readasarrays=True, recharge=rech)
-
-        # wel file
-        wel = flopy.mf6.ModflowGwfwel(
-            gwf,
-            print_input=True,
-            print_flows=True,
-            maxbound=maxwel,
-            stress_period_data=wd6,
-            save_flows=False,
-        )
-
-        # chd files
-        chd = flopy.mf6.modflow.mfgwfchd.ModflowGwfchd(
-            gwf, maxbound=maxchd, stress_period_data=cd6, save_flows=False
-        )
-        # csub files
-        opth = f"{name}.csub.obs"
-        csub = flopy.mf6.ModflowGwfcsub(
-            gwf,
-            head_based=True,
-            save_flows=True,
-            ninterbeds=0,
-            cg_theta=theta,
-            cg_ske_cr=crnd0,
-            packagedata=None,
-        )
-        obspos = [(0, 4, 4), (1, 4, 4), (2, 4, 4)]
-        obstype = ["compaction-cell", "csub-cell"]
-        obstag = ["tcomp", "csub"]
-        obsarr = []
-        for iobs, cobs in enumerate(obstype):
-            for jobs, otup in enumerate(obspos):
-                otag = f"{obstag[iobs]}{jobs + 1}"
-                obsarr.append((otag, cobs, otup))
-
-        obsarr2 = []
-        obstype2 = [
-            "csub",
-            "inelastic-csub",
-            "elastic-csub",
-            "sk",
-            "ske",
-            "thickness",
-            "theta",
-            "interbed-compaction",
-            "inelastic-compaction",
-            "elastic-compaction",
-            "delay-flowtop",
-            "delay-flowbot",
-        ]
-        iobs = 0
-        for cobs in obstype2:
-            iobs += 1
-            otag = f"obs{iobs:03d}"
-            obsarr2.append((otag, cobs, (0,)))
-
-        obstype3 = [
-            "delay-preconstress",
-            "delay-head",
-            "delay-gstress",
-            "delay-estress",
-            "delay-compaction",
-            "delay-thickness",
-            "delay-theta",
-        ]
-        for cobs in obstype3:
-            iobs += 1
-            otag = f"obs{iobs:03d}"
-            obsarr2.append((otag, cobs, (0,), (0,)))
-
-        obsarr3 = []
-        obstype4 = [
-            "gstress-cell",
-            "estress-cell",
-            "thickness-cell",
-            "coarse-csub",
-            "wcomp-csub-cell",
-            "coarse-compaction",
-            "coarse-theta",
-            "coarse-thickness",
-            "csub-cell",
-            "ske-cell",
-            "sk-cell",
-            "theta-cell",
-            "compaction-cell",
-        ]
-        for cobs in obstype4:
-            iobs += 1
-            otag = f"obs{iobs:03d}"
-            obsarr3.append((otag, cobs, obspos[-1]))
-
-        orecarray = {}
-        orecarray["csub_obs.csv"] = obsarr
-        orecarray["interbed_obs.csv"] = obsarr2
-        orecarray["coarse_cell_obs.csv"] = obsarr3
-
-        csub_obs_package = csub.obs.initialize(
-            filename=opth, digits=10, print_input=True, continuous=orecarray
-        )
-
-        # output control
-        oc = flopy.mf6.ModflowGwfoc(
-            gwf,
-            budget_filerecord=f"{name}.cbc",
-            head_filerecord=f"{name}.hds",
-            headprintrecord=[
-                ("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")
-            ],
-            saverecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
-            printrecord=[("HEAD", "LAST"), ("BUDGET", "ALL")],
-        )
-
-        return sim
-
-    def eval_case(self, sim, data):
-        print("evaluating compaction...")
-
-        # MODFLOW 6 total compaction results
-        fpth = os.path.join(sim.simpath, "csub_obs.csv")
-        tc = np.genfromtxt(fpth, names=True, delimiter=",")
-
-        # regression compaction results
-        cpth = "mf6_regression"
-        fpth = os.path.join(sim.simpath, cpth, "csub_obs.csv")
-        tc0 = np.genfromtxt(fpth, names=True, delimiter=",")
-
-        # calculate maximum absolute error
-        diff = tc["TCOMP3"] - tc0["TCOMP3"]
-        diffmax = np.abs(diff).max()
-        msg = f"maximum absolute total-compaction difference ({diffmax}) "
-
-        # write summary
-        fpth = os.path.join(
-            sim.simpath, f"{os.path.basename(sim.name)}.comp.cmp.out"
-        )
-        f = open(fpth, "w")
+    obspos = [(0, 4, 4), (1, 4, 4), (2, 4, 4)]
+    obstype = ["compaction-cell", "csub-cell"]
+    obstag = ["tcomp", "csub"]
+    obsarr = []
+    for iobs, cobs in enumerate(obstype):
+        for jobs, otup in enumerate(obspos):
+            otag = f"{obstag[iobs]}{jobs + 1}"
+            obsarr.append((otag, cobs, otup))
+
+    obsarr2 = []
+    obstype2 = [
+        "csub",
+        "inelastic-csub",
+        "elastic-csub",
+        "sk",
+        "ske",
+        "thickness",
+        "theta",
+        "interbed-compaction",
+        "inelastic-compaction",
+        "elastic-compaction",
+        "delay-flowtop",
+        "delay-flowbot",
+    ]
+    iobs = 0
+    for cobs in obstype2:
+        iobs += 1
+        otag = f"obs{iobs:03d}"
+        obsarr2.append((otag, cobs, (0,)))
+
+    obstype3 = [
+        "delay-preconstress",
+        "delay-head",
+        "delay-gstress",
+        "delay-estress",
+        "delay-compaction",
+        "delay-thickness",
+        "delay-theta",
+    ]
+    for cobs in obstype3:
+        iobs += 1
+        otag = f"obs{iobs:03d}"
+        obsarr2.append((otag, cobs, (0,), (0,)))
+
+    obsarr3 = []
+    obstype4 = [
+        "gstress-cell",
+        "estress-cell",
+        "thickness-cell",
+        "coarse-csub",
+        "wcomp-csub-cell",
+        "coarse-compaction",
+        "coarse-theta",
+        "coarse-thickness",
+        "csub-cell",
+        "ske-cell",
+        "sk-cell",
+        "theta-cell",
+        "compaction-cell",
+    ]
+    for cobs in obstype4:
+        iobs += 1
+        otag = f"obs{iobs:03d}"
+        obsarr3.append((otag, cobs, obspos[-1]))
+
+    orecarray = {}
+    orecarray["csub_obs.csv"] = obsarr
+    orecarray["interbed_obs.csv"] = obsarr2
+    orecarray["coarse_cell_obs.csv"] = obsarr3
+
+    csub_obs_package = csub.obs.initialize(
+        filename=opth, digits=10, print_input=True, continuous=orecarray
+    )
+
+    # output control
+    oc = flopy.mf6.ModflowGwfoc(
+        gwf,
+        budget_filerecord=f"{name}.cbc",
+        head_filerecord=f"{name}.hds",
+        headprintrecord=[("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")],
+        saverecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
+        printrecord=[("HEAD", "LAST"), ("BUDGET", "ALL")],
+    )
+
+    return sim
+
+
+def check_output(idx, test):
+    # MODFLOW 6 total compaction results
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
+    tc = np.genfromtxt(fpth, names=True, delimiter=",")
+
+    # regression compaction results
+    cpth = "mf6_regression"
+    fpth = os.path.join(test.workspace, cpth, "csub_obs.csv")
+    tc0 = np.genfromtxt(fpth, names=True, delimiter=",")
+
+    # calculate maximum absolute error
+    diff = tc["TCOMP3"] - tc0["TCOMP3"]
+    diffmax = np.abs(diff).max()
+    msg = f"maximum absolute total-compaction difference ({diffmax}) "
+
+    # write summary
+    fpth = os.path.join(
+        test.workspace, f"{os.path.basename(test.name)}.comp.cmp.out"
+    )
+    with open(fpth, "w") as f:
         for i in range(diff.shape[0]):
             line = f"{tc0['time'][i]:10.2g}"
             line += f"{tc['TCOMP3'][i]:10.2g}"
             line += f"{tc0['TCOMP3'][i]:10.2g}"
             line += f"{diff[i]:10.2g}"
             f.write(line + "\n")
-        f.close()
-
-        if diffmax > self.dtol:
-            sim.success = False
-            msg += f"exceeds {self.dtol}"
-            assert diffmax < self.dtol, msg
-        else:
-            sim.success = True
-            print("    " + msg)
-
-        # get results from listing file
-        fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
-        budl = flopy.utils.Mf6ListBudget(fpth)
-        names = list(self.bud_lst)
-        d0 = budl.get_budget(names=names)[0]
-        dtype = d0.dtype
-        nbud = d0.shape[0]
-
-        # get results from cbc file
-        cbc_bud = ["CSUB-CGELASTIC", "CSUB-WATERCOMP"]
-        d = np.recarray(nbud, dtype=dtype)
-        for key in self.bud_lst:
-            d[key] = 0.0
-        fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
-        cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
-        kk = cobj.get_kstpkper()
-        times = cobj.get_times()
-        for idx, (k, t) in enumerate(zip(kk, times)):
-            for text in cbc_bud:
-                qin = 0.0
-                qout = 0.0
-                v = cobj.get_data(kstpkper=k, text=text)[0]
-                for kk in range(v.shape[0]):
-                    for ii in range(v.shape[1]):
-                        for jj in range(v.shape[2]):
-                            vv = v[kk, ii, jj]
-                            if vv < 0.0:
-                                qout -= vv
-                            else:
-                                qin += vv
-                d["totim"][idx] = t
-                d["time_step"][idx] = k[0]
-                d["stress_period"] = k[1]
-                key = f"{text}_IN"
-                d[key][idx] = qin
-                key = f"{text}_OUT"
-                d[key][idx] = qout
-
-        diff = np.zeros((nbud, len(self.bud_lst)), dtype=float)
-        for idx, key in enumerate(self.bud_lst):
-            diff[:, idx] = d0[key] - d[key]
-        diffmax = np.abs(diff).max()
-        msg = f"maximum absolute total-budget difference ({diffmax}) "
-
-        # write summary
-        fpth = os.path.join(
-            sim.simpath, f"{os.path.basename(sim.name)}.bud.cmp.out"
-        )
-        f = open(fpth, "w")
+
+    if diffmax > dtol:
+        test.success = False
+        msg += f"exceeds {dtol}"
+        assert diffmax < dtol, msg
+    else:
+        test.success = True
+        print("    " + msg)
+
+    # get results from listing file
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
+    budl = flopy.utils.Mf6ListBudget(fpth)
+    names = list(bud_lst)
+    d0 = budl.get_budget(names=names)[0]
+    dtype = d0.dtype
+    nbud = d0.shape[0]
+
+    # get results from cbc file
+    cbc_bud = ["CSUB-CGELASTIC", "CSUB-WATERCOMP"]
+    d = np.recarray(nbud, dtype=dtype)
+    for key in bud_lst:
+        d[key] = 0.0
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
+    cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
+    kk = cobj.get_kstpkper()
+    times = cobj.get_times()
+    for i, (k, t) in enumerate(zip(kk, times)):
+        for text in cbc_bud:
+            qin = 0.0
+            qout = 0.0
+            v = cobj.get_data(kstpkper=k, text=text)[0]
+            for kk in range(v.shape[0]):
+                for ii in range(v.shape[1]):
+                    for jj in range(v.shape[2]):
+                        vv = v[kk, ii, jj]
+                        if vv < 0.0:
+                            qout -= vv
+                        else:
+                            qin += vv
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
+            d["stress_period"] = k[1]
+            key = f"{text}_IN"
+            d[key][i] = qin
+            key = f"{text}_OUT"
+            d[key][i] = qout
+
+    diff = np.zeros((nbud, len(bud_lst)), dtype=float)
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
+    diffmax = np.abs(diff).max()
+    msg = f"maximum absolute total-budget difference ({diffmax}) "
+
+    # write summary
+    fpth = os.path.join(
+        test.workspace, f"{os.path.basename(test.name)}.bud.cmp.out"
+    )
+    with open(fpth, "w") as f:
         for i in range(diff.shape[0]):
             if i == 0:
                 line = f"{'TIME':>10s}"
-                for idx, key in enumerate(self.bud_lst):
+                for j, key in enumerate(bud_lst):
                     line += f"{key + '_LST':>25s}"
                     line += f"{key + '_CBC':>25s}"
                     line += f"{key + '_DIF':>25s}"
                 f.write(line + "\n")
             line = f"{d['totim'][i]:10g}"
-            for idx, key in enumerate(self.bud_lst):
+            for j, key in enumerate(bud_lst):
                 line += f"{d0[key][i]:25g}"
                 line += f"{d[key][i]:25g}"
-                line += f"{diff[i, idx]:25g}"
+                line += f"{diff[i, j]:25g}"
             f.write(line + "\n")
-        f.close()
-
-        if diffmax > self.budtol:
-            sim.success = False
-            msg += f"exceeds {self.dtol}"
-            assert diffmax < self.dtol, msg
-        else:
-            sim.success = True
-            print("    " + msg)
-
-
-@parametrize_with_cases(
-    "case",
-    cases=[
-        GwfCsubSkCases,
-    ],
-)
-def test_mf6model(case, targets):
-    data, sim, cmp, evl = case
-    sim.write_simulation()
-    if cmp:
-        cmp.write_simulation()
-    test = TestSimulation(
-        name=data.name,
-        exe_dict=targets,
-        exfunc=evl,
-        idxsim=0,
-        mf6_regression=True,
+
+    if diffmax > budtol:
+        test.success = False
+        msg += f"exceeds {dtol}"
+        assert diffmax < dtol, msg
+    else:
+        test.success = True
+        print("    " + msg)
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
+        compare="mf6_regression",
     )
-    test.set_model(sim.simulation_data.mfpath.get_sim_path(), testModel=False)
     test.run()
-    test.compare()
-    evl(test, data)
diff --git a/autotest/test_gwf_csub_sk02.py b/autotest/test_gwf_csub_sk02.py
index 5ae15cf0b0f..62f546f77e9 100644
--- a/autotest/test_gwf_csub_sk02.py
+++ b/autotest/test_gwf_csub_sk02.py
@@ -3,20 +3,19 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from modflow_devtools.misc import is_in_ci
-from simulation import TestSimulation
-
-ex = ["csub_sk02a", "csub_sk02b", "csub_sk02c", "csub_sk02d"]
-constantcv = [True for idx in range(len(ex))]
-cmppths = ["mf6_regression" for idx in range(len(ex))]
-tops = [150.0 for idx in range(len(ex))]
-newtons = [True for idx in range(len(ex))]
+
+cases = ["csub_sk02a", "csub_sk02b", "csub_sk02c", "csub_sk02d"]
+constantcv = [True for _ in range(len(cases))]
+cmppths = ["mf6_regression" for _ in range(len(cases))]
+tops = [150.0 for _ in range(len(cases))]
+newtons = [True for _ in range(len(cases))]
 ump = [None, None, True, True]
 iump = [0, 0, 1, 1]
-eslag = [True for idx in range(len(ex))]
+eslag = [True for _ in range(len(cases))]
 icrcc = [0, 1, 0, 1]
-htol = [None for idx in range(len(ex))]
+htol = [None for _ in range(len(cases))]
 dtol = 1e-3
 bud_lst = [
     "CSUB-CGELASTIC_IN",
@@ -28,10 +27,10 @@
 # static model data
 nlay, nrow, ncol = 3, 10, 10
 nper = 31
-perlen = [1.0] + [365.2500000 for i in range(nper - 1)]
-nstp = [1] + [6 for i in range(nper - 1)]
-tsmult = [1.0] + [1.3 for i in range(nper - 1)]
-steady = [True] + [False for i in range(nper - 1)]
+perlen = [1.0] + [365.2500000 for _ in range(nper - 1)]
+nstp = [1] + [6 for _ in range(nper - 1)]
+tsmult = [1.0] + [1.3 for _ in range(nper - 1)]
+steady = [True] + [False for _ in range(nper - 1)]
 delr, delc = 1000.0, 2000.0
 top = 150.0
 botm = [-100, -150.0, -350.0]
@@ -61,8 +60,8 @@
 hclose, rclose, relax = 1e-9, 1e-6, 1.0
 
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 # all cells are active
 ib = 1
@@ -178,7 +177,7 @@
 
 
 def get_model(idx, ws):
-    name = ex[idx]
+    name = cases[idx]
     newton = newtons[idx]
     newtonoptions = None
     imsla = "CG"
@@ -321,33 +320,28 @@ def get_model(idx, ws):
     return sim
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     # build MODFLOW 6 files
-    ws = dir
-    sim = get_model(idx, ws)
+    sim = get_model(idx, test.workspace)
 
     # build comparison files
     cpth = cmppths[idx]
-    ws = os.path.join(dir, cpth)
+    ws = os.path.join(test.workspace, cpth)
     mc = get_model(idx, ws)
-
     return sim, mc
 
 
-def eval_comp(sim):
-    print("evaluating compaction...")
-
+def check_output(idx, test):
     # MODFLOW 6 total compaction results
-    fpth = os.path.join(sim.simpath, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
         assert False, f'could not load data from "{fpth}"'
 
     # comparision total compaction results
-    cpth = cmppths[sim.idxsim]
-    fpth = os.path.join(sim.simpath, cpth, "csub_obs.csv")
+    cpth = cmppths[idx]
+    fpth = os.path.join(test.workspace, cpth, "csub_obs.csv")
     try:
         tc0 = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -360,27 +354,26 @@ def eval_comp(sim):
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.comp.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.comp.cmp.out"
     )
-    f = open(fpth, "w")
-    for i in range(diff.shape[0]):
-        line = f"{tc0['time'][i]:10.2g}"
-        line += f"{tc['TCOMP3'][i]:10.2g}"
-        line += f"{tc0['TCOMP3'][i]:10.2g}"
-        line += f"{diff[i]:10.2g}"
-        f.write(line + "\n")
-    f.close()
+    with open(fpth, "w") as f:
+        for i in range(diff.shape[0]):
+            line = f"{tc0['time'][i]:10.2g}"
+            line += f"{tc['TCOMP3'][i]:10.2g}"
+            line += f"{tc0['TCOMP3'][i]:10.2g}"
+            line += f"{diff[i]:10.2g}"
+            f.write(line + "\n")
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
     # get results from listing file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
     budl = flopy.utils.Mf6ListBudget(fpth)
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
@@ -392,11 +385,11 @@ def eval_comp(sim):
     d = np.recarray(nbud, dtype=dtype)
     for key in bud_lst:
         d[key] = 0.0
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
     cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -409,13 +402,13 @@ def eval_comp(sim):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
     for idx, key in enumerate(bud_lst):
@@ -425,49 +418,42 @@ def eval_comp(sim):
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.bud.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.bud.cmp.out"
     )
-    f = open(fpth, "w")
-    for i in range(diff.shape[0]):
-        if i == 0:
-            line = f"{'TIME':>10s}"
-            for idx, key in enumerate(bud_lst):
-                line += f"{key + '_LST':>25s}"
-                line += f"{key + '_CBC':>25s}"
-                line += f"{key + '_DIF':>25s}"
+    with open(fpth, "w") as f:
+        for i in range(diff.shape[0]):
+            if i == 0:
+                line = f"{'TIME':>10s}"
+                for key in bud_lst:
+                    line += f"{key + '_LST':>25s}"
+                    line += f"{key + '_CBC':>25s}"
+                    line += f"{key + '_DIF':>25s}"
+                f.write(line + "\n")
+            line = f"{d['totim'][i]:10g}"
+            for ii, key in enumerate(bud_lst):
+                line += f"{d0[key][i]:25g}"
+                line += f"{d[key][i]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
-        line = f"{d['totim'][i]:10g}"
-        for idx, key in enumerate(bud_lst):
-            line += f"{d0[key][i]:25g}"
-            line += f"{d[key][i]:25g}"
-            line += f"{diff[i, idx]:25g}"
-        f.write(line + "\n")
-    f.close()
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_comp,
-            htol=htol[idx],
-            idxsim=idx,
-            mf6_regression=True,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        htol=htol[idx],
+        compare="mf6_regression",
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_sk03.py b/autotest/test_gwf_csub_sk03.py
index f886dba8a4b..a12fca651b0 100644
--- a/autotest/test_gwf_csub_sk03.py
+++ b/autotest/test_gwf_csub_sk03.py
@@ -4,15 +4,15 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["csub_sk03a"]
-constantcv = [True for idx in range(len(ex))]
-cmppths = ["mf6_regression" for idx in range(len(ex))]
-newtons = [True for idx in range(len(ex))]
+cases = ["csub_sk03a"]
+constantcv = [True for _ in range(len(cases))]
+cmppths = ["mf6_regression" for _ in range(len(cases))]
+newtons = [True for _ in range(len(cases))]
 icrcc = [0, 1, 0, 1]
-htol = [None for idx in range(len(ex))]
+htol = [None for _ in range(len(cases))]
 dtol = 1e-3
 bud_lst = [
     "CSUB-CGELASTIC_IN",
@@ -31,14 +31,14 @@
 totim = perlen.sum() - perlen[0]
 nstp = [1, nsec * 2]
 tsmult = [1.0, 1.00]
-steady = [True] + [False for i in range(nper - 1)]
+steady = [True] + [False for _ in range(nper - 1)]
 
 # spatial discretization
 ft2m = 1.0 / 3.28081
 nlay, nrow, ncol = 3, 21, 20
 delr = np.ones(ncol, dtype=float) * 0.5
-for idx in range(1, ncol):
-    delr[idx] = min(delr[idx - 1] * 1.2, 15.0)
+for i in range(1, ncol):
+    delr[i] = min(delr[i - 1] * 1.2, 15.0)
 delc = 50.0
 top = 0.0
 botm = np.array([-40, -70.0, -100.0], dtype=float) * ft2m
@@ -61,8 +61,8 @@
 hclose, rclose, relax = 1e-9, 1e-6, 1.0
 
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 # all cells are active
 ib = 1
@@ -231,7 +231,7 @@
 
 
 def get_model(idx, ws):
-    name = ex[idx]
+    name = cases[idx]
     newton = newtons[idx]
     newtonoptions = None
     imsla = "CG"
@@ -500,32 +500,28 @@ def get_model(idx, ws):
 
 
 # SUB package problem 3
-def build_model(idx, dir):
-
+def build_models(idx, test):
     # build MODFLOW 6 files
-    ws = dir
-    sim = get_model(idx, ws)
+    sim = get_model(idx, test.workspace)
 
     # build comparison files
     cpth = cmppths[idx]
-    ws = os.path.join(dir, cpth)
+    ws = os.path.join(test.workspace, cpth)
     mc = get_model(idx, ws)
 
     return sim, mc
 
 
-def eval_comp(sim):
-    print("evaluating compaction...")
-
+def check_output(idx, test):
     # MODFLOW 6 total compaction results
-    fpth = os.path.join(sim.simpath, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
         assert False, f'could not load data from "{fpth}"'
 
     # get results from listing file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
     budl = flopy.utils.Mf6ListBudget(fpth)
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
@@ -537,11 +533,11 @@ def eval_comp(sim):
     d = np.recarray(nbud, dtype=dtype)
     for key in bud_lst:
         d[key] = 0.0
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
     cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -554,66 +550,59 @@ def eval_comp(sim):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, key in enumerate(bud_lst):
-        diff[:, idx] = d0[key] - d[key]
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
     diffmax = np.abs(diff).max()
     msg = f"maximum absolute total-budget difference ({diffmax}) "
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.bud.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.bud.cmp.out"
     )
-    f = open(fpth, "w")
-    for i in range(diff.shape[0]):
-        if i == 0:
-            line = f"{'TIME':>10s}"
-            for idx, key in enumerate(bud_lst):
-                line += f"{key + '_LST':>25s}"
-                line += f"{key + '_CBC':>25s}"
-                line += f"{key + '_DIF':>25s}"
+    with open(fpth, "w") as f:
+        for i in range(diff.shape[0]):
+            if i == 0:
+                line = f"{'TIME':>10s}"
+                for key in bud_lst:
+                    line += f"{key + '_LST':>25s}"
+                    line += f"{key + '_CBC':>25s}"
+                    line += f"{key + '_DIF':>25s}"
+                f.write(line + "\n")
+            line = f"{d['totim'][i]:10g}"
+            for ii, key in enumerate(bud_lst):
+                line += f"{d0[key][i]:25g}"
+                line += f"{d[key][i]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
-        line = f"{d['totim'][i]:10g}"
-        for idx, key in enumerate(bud_lst):
-            line += f"{d0[key][i]:25g}"
-            line += f"{d[key][i]:25g}"
-            line += f"{diff[i, idx]:25g}"
-        f.write(line + "\n")
-    f.close()
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_comp,
-            htol=htol[idx],
-            idxsim=idx,
-            mf6_regression=True,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        htol=htol[idx],
+        compare="mf6_regression",
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_sk04_nr.py b/autotest/test_gwf_csub_sk04_nr.py
index edb9f0409e8..8b0e5c748e6 100644
--- a/autotest/test_gwf_csub_sk04_nr.py
+++ b/autotest/test_gwf_csub_sk04_nr.py
@@ -3,10 +3,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = (
+cases = (
     "csub_sk04a",
     "csub_sk04b",
     "csub_sk04c",
@@ -33,10 +33,10 @@
 nlay, nrow, ncol = 2, 1, 2
 nper = 3
 tsp0 = 1.0
-perlen = [tsp0] + [365.2500000 for i in range(nper - 1)]
-nstp = [1] + [200 for i in range(nper - 1)]
-tsmult = [1.0] + [1.0 for i in range(nper - 1)]
-steady = [True] + [False for i in range(nper - 1)]
+perlen = [tsp0] + [365.2500000 for _ in range(nper - 1)]
+nstp = [1] + [200 for _ in range(nper - 1)]
+tsmult = [1.0] + [1.0 for _ in range(nper - 1)]
+steady = [True] + [False for _ in range(nper - 1)]
 delr, delc = 1000.0, 1000.0
 top = 0.0
 botm = [-10.0, -20.0]
@@ -55,8 +55,8 @@
 hclose, rclose, relax = 1e-9, 1e-3, 1.0
 
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 # all cells are active
 ib = 1
@@ -77,12 +77,12 @@
 crnd0[:, 0, 0] = 0.0
 
 
-def build_model(idx, dir):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
     newton = newtons[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -244,18 +244,16 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_comp(sim):
-    print("evaluating compaction...")
-
+def check_output(idx, test):
     # MODFLOW 6 total compaction results
-    fpth = os.path.join(sim.simpath, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
         assert False, f'could not load data from "{fpth}"'
 
     # get results from listing file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
     budl = flopy.utils.Mf6ListBudget(fpth)
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
@@ -267,11 +265,11 @@ def eval_comp(sim):
     d = np.recarray(nbud, dtype=dtype)
     for key in bud_lst:
         d[key] = 0.0
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
     cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -284,64 +282,57 @@ def eval_comp(sim):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, key in enumerate(bud_lst):
-        diff[:, idx] = d0[key] - d[key]
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
     diffmax = np.abs(diff).max()
     msg = f"maximum absolute total-budget difference ({diffmax}) "
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.bud.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.bud.cmp.out"
     )
-    f = open(fpth, "w")
-    for i in range(diff.shape[0]):
-        if i == 0:
-            line = f"{'TIME':>10s}"
-            for idx, key in enumerate(bud_lst):
-                line += f"{key + '_LST':>25s}"
-                line += f"{key + '_CBC':>25s}"
-                line += f"{key + '_DIF':>25s}"
+    with open(fpth, "w") as f:
+        for i in range(diff.shape[0]):
+            if i == 0:
+                line = f"{'TIME':>10s}"
+                for key in bud_lst:
+                    line += f"{key + '_LST':>25s}"
+                    line += f"{key + '_CBC':>25s}"
+                    line += f"{key + '_DIF':>25s}"
+                f.write(line + "\n")
+            line = f"{d['totim'][i]:10g}"
+            for ii, key in enumerate(bud_lst):
+                line += f"{d0[key][i]:25g}"
+                line += f"{d[key][i]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
-        line = f"{d['totim'][i]:10g}"
-        for idx, key in enumerate(bud_lst):
-            line += f"{d0[key][i]:25g}"
-            line += f"{d[key][i]:25g}"
-            line += f"{diff[i, idx]:25g}"
-        f.write(line + "\n")
-    f.close()
 
     if diffmax > budtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_comp,
-            htol=htol,
-            idxsim=idx,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        htol=htol,
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_sub01.py b/autotest/test_gwf_csub_sub01.py
index 4327c62e3fb..d0e40fcc99a 100644
--- a/autotest/test_gwf_csub_sub01.py
+++ b/autotest/test_gwf_csub_sub01.py
@@ -3,14 +3,14 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
+cases = ["csub_sub01a", "csub_sub01b"]
 paktest = "csub"
 budtol = 1e-2
-ex = ["csub_sub01a", "csub_sub01b"]
 compression_indices = [None, True]
-ndcell = [19] * len(ex)
+ndcell = [19] * len(cases)
 
 # static model data
 # spatial discretization
@@ -23,10 +23,10 @@
 
 # temporal discretization
 nper = 1
-perlen = [1000.0 for i in range(nper)]
-nstp = [100 for i in range(nper)]
-tsmult = [1.05 for i in range(nper)]
-steady = [False for i in range(nper)]
+perlen = [1000.0 for _ in range(nper)]
+nstp = [100 for _ in range(nper)]
+tsmult = [1.05 for _ in range(nper)]
+steady = [False for _ in range(nper)]
 
 strt = 0.0
 strt6 = 1.0
@@ -41,8 +41,8 @@
 hclose, rclose, relax = 1e-6, 1e-6, 0.97
 
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 ib = 1
 
@@ -78,7 +78,7 @@
 
 
 def get_model(idx, ws):
-    name = ex[idx]
+    name = cases[idx]
 
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
@@ -215,31 +215,27 @@ def get_model(idx, ws):
     return sim
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     # build MODFLOW 6 files
-    ws = dir
-    sim = get_model(idx, ws)
+    sim = get_model(idx, test.workspace)
 
     # build MODFLOW-2005 files
-    ws = os.path.join(dir, "mf6_regression")
+    ws = os.path.join(test.workspace, "mf6_regression")
     mc = get_model(idx, ws)
 
     return sim, mc
 
 
-def eval_sub(sim):
-    print("evaluating subsidence...")
-
+def check_output(idx, test):
     # MODFLOW 6 total compaction results
-    fpth = os.path.join(sim.simpath, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
         assert False, f'could not load data from "{fpth}"'
 
     # comparison total compaction results
-    fpth = os.path.join(sim.simpath, "mf6_regression", "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "mf6_regression", "csub_obs.csv")
     try:
         tc0 = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -253,40 +249,37 @@ def eval_sub(sim):
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.comp.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.comp.cmp.out"
     )
-    f = open(fpth, "w")
-    line = f"{'TOTIM':>15s}"
-    line += f" {'CSUB':>15s}"
-    line += f" {'MF':>15s}"
-    line += f" {'DIFF':>15s}"
-    f.write(line + "\n")
-    for i in range(diff.shape[0]):
-        line = f"{tc0['time'][i]:15g}"
-        line += f" {tc['TCOMP'][i]:15g}"
-        line += f" {tc0['TCOMP'][i]:15g}"
-        line += f" {diff[i]:15g}"
+    with open(fpth, "w") as f:
+        line = f"{'TOTIM':>15s}"
+        line += f" {'CSUB':>15s}"
+        line += f" {'MF':>15s}"
+        line += f" {'DIFF':>15s}"
         f.write(line + "\n")
-    f.close()
+        for i in range(diff.shape[0]):
+            line = f"{tc0['time'][i]:15g}"
+            line += f" {tc['TCOMP'][i]:15g}"
+            line += f" {tc0['TCOMP'][i]:15g}"
+            line += f" {diff[i]:15g}"
+            f.write(line + "\n")
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
     # compare budgets
-    cbc_compare(sim)
-
-    return
+    cbc_compare(test)
 
 
 # compare cbc and lst budgets
-def cbc_compare(sim):
+def cbc_compare(test):
     # open cbc file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
     cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # build list of cbc data to retrieve
@@ -303,7 +296,7 @@ def cbc_compare(sim):
             bud_lst.append(f"{t}_OUT")
 
     # get results from listing file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
     budl = flopy.utils.Mf6ListBudget(fpth)
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
@@ -316,7 +309,7 @@ def cbc_compare(sim):
     # get data from cbc dile
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -334,64 +327,57 @@ def cbc_compare(sim):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, key in enumerate(bud_lst):
-        diff[:, idx] = d0[key] - d[key]
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
     diffmax = np.abs(diff).max()
     msg = f"maximum absolute total-budget difference ({diffmax}) "
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.bud.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.bud.cmp.out"
     )
-    f = open(fpth, "w")
-    for i in range(diff.shape[0]):
-        if i == 0:
-            line = f"{'TIME':>10s}"
-            for idx, key in enumerate(bud_lst):
-                line += f"{key + '_LST':>25s}"
-                line += f"{key + '_CBC':>25s}"
-                line += f"{key + '_DIF':>25s}"
+    with open(fpth, "w") as f:
+        for i in range(diff.shape[0]):
+            if i == 0:
+                line = f"{'TIME':>10s}"
+                for key in bud_lst:
+                    line += f"{key + '_LST':>25s}"
+                    line += f"{key + '_CBC':>25s}"
+                    line += f"{key + '_DIF':>25s}"
+                f.write(line + "\n")
+            line = f"{d['totim'][i]:10g}"
+            for ii, key in enumerate(bud_lst):
+                line += f"{d0[key][i]:25g}"
+                line += f"{d[key][i]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
-        line = f"{d['totim'][i]:10g}"
-        for idx, key in enumerate(bud_lst):
-            line += f"{d0[key][i]:25g}"
-            line += f"{d[key][i]:25g}"
-            line += f"{diff[i, idx]:25g}"
-        f.write(line + "\n")
-    f.close()
 
     if diffmax > budtol:
-        sim.success = False
+        test.success = False
         msg += f"diffmax {diffmax} exceeds tolerance {budtol}"
         assert diffmax < budtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_sub,
-            idxsim=idx,
-            mf6_regression=True,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
+        compare="mf6_regression",
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_sub01_adjmat.py b/autotest/test_gwf_csub_sub01_adjmat.py
index 694799c26da..c37adcaf16d 100644
--- a/autotest/test_gwf_csub_sub01_adjmat.py
+++ b/autotest/test_gwf_csub_sub01_adjmat.py
@@ -3,16 +3,15 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
+cases = ["csub_sub01_adj"]
 paktest = "csub"
 budtol = 1e-2
-
 compdir = "mf6"
-ex = ["csub_sub01_adj"]
 compression_indices = [None]
-ndcell = [19] * len(ex)
+ndcell = [19] * len(cases)
 
 # static model data
 # spatial discretization
@@ -25,10 +24,10 @@
 
 # temporal discretization
 nper = 1
-perlen = [1000.0 for i in range(nper)]
-nstp = [100 for i in range(nper)]
-tsmult = [1.05 for i in range(nper)]
-steady = [False for i in range(nper)]
+perlen = [1000.0 for _ in range(nper)]
+nstp = [100 for _ in range(nper)]
+tsmult = [1.05 for _ in range(nper)]
+steady = [False for _ in range(nper)]
 
 strt = 0.0
 strt6 = 1.0
@@ -43,8 +42,8 @@
 hclose, rclose, relax = 1e-12, 1e-6, 0.97
 
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 ib = 1
 
@@ -85,18 +84,18 @@
 ]
 
 
-def build_model(idx, dir):
-    sim = get_model(idx, dir, adjustmat=True)
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace, adjustmat=True)
 
     # build MODFLOW-6 with constant material properties
-    pth = os.path.join(dir, compdir)
+    pth = os.path.join(test.workspace, compdir)
     mc = get_model(idx, pth, None)
 
     return sim, mc
 
 
 def get_model(idx, dir, adjustmat=False):
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
     ws = dir
@@ -221,18 +220,16 @@ def calc_theta_thick(comp, thickini=1.0):
     return poro, b
 
 
-def eval_sub(sim):
-    print("evaluating subsidence...")
-
+def check_output(idx, test):
     # MODFLOW 6 compaction results
-    fpth = os.path.join(sim.simpath, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
         assert False, f'could not load data from "{fpth}"'
 
     # MODFLOW 6 base compaction results
-    fpth = os.path.join(sim.simpath, compdir, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, compdir, "csub_obs.csv")
     try:
         tcb = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -246,28 +243,27 @@ def eval_sub(sim):
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.comp.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.comp.cmp.out"
     )
-    f = open(fpth, "w")
-    line = f"{'TOTIM':>15s}"
-    line += f" {'CSUB':>15s}"
-    line += f" {'MF':>15s}"
-    line += f" {'DIFF':>15s}"
-    f.write(line + "\n")
-    for i in range(diff.shape[0]):
-        line = f"{tc['time'][i]:15g}"
-        line += f" {tc['TCOMP'][i]:15g}"
-        line += f" {tcb['TCOMP'][i]:15g}"
-        line += f" {diff[i]:15g}"
+    with open(fpth, "w") as f:
+        line = f"{'TOTIM':>15s}"
+        line += f" {'CSUB':>15s}"
+        line += f" {'MF':>15s}"
+        line += f" {'DIFF':>15s}"
         f.write(line + "\n")
-    f.close()
+        for i in range(diff.shape[0]):
+            line = f"{tc['time'][i]:15g}"
+            line += f" {tc['TCOMP'][i]:15g}"
+            line += f" {tcb['TCOMP'][i]:15g}"
+            line += f" {diff[i]:15g}"
+            f.write(line + "\n")
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol:15.7g}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
     # calculate theta and porosity from total interbed compaction
@@ -287,11 +283,11 @@ def eval_sub(sim):
             + f"difference ({diffmax:15.7g}) "
         )
         if diffmax > dtol:
-            sim.success = False
+            test.success = False
             msg += f"exceeds {dtol:15.7g}"
             assert diffmax < dtol, msg
         else:
-            sim.success = True
+            test.success = True
             print("    " + msg)
 
     # calculate theta and porosity from interbed cell compaction
@@ -317,11 +313,11 @@ def eval_sub(sim):
                 + f"({diffmax:15.7g}) "
             )
             if diffmax > dtol:
-                sim.success = False
+                test.success = False
                 msg += f"exceeds {dtol:15.7g}"
                 assert diffmax < dtol, msg
             else:
-                sim.success = True
+                test.success = True
                 print("    " + msg)
         calci["THICK"] += calc["THICK"]
         calci["THETA"] += calc["THICK"] * calc["THETA"]
@@ -337,21 +333,21 @@ def eval_sub(sim):
         )
         msg += "calculated from individual interbed cell values "
         if diffmax > dtol:
-            sim.success = False
+            test.success = False
             msg += f"exceeds {dtol:15.7g}"
             assert diffmax < dtol, msg
         else:
-            sim.success = True
+            test.success = True
             print("    " + msg)
 
     # compare budgets
-    cbc_compare(sim)
+    cbc_compare(test)
 
 
 # compare cbc and lst budgets
-def cbc_compare(sim):
+def cbc_compare(test):
     # open cbc file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
     cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # build list of cbc data to retrieve
@@ -368,7 +364,7 @@ def cbc_compare(sim):
             bud_lst.append(f"{t}_OUT")
 
     # get results from listing file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
     budl = flopy.utils.Mf6ListBudget(fpth)
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
@@ -381,7 +377,7 @@ def cbc_compare(sim):
     # get data from cbc dile
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -399,57 +395,58 @@ def cbc_compare(sim):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, key in enumerate(bud_lst):
-        diff[:, idx] = d0[key] - d[key]
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
     diffmax = np.abs(diff).max()
     msg = f"maximum absolute total-budget difference ({diffmax}) "
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.bud.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.bud.cmp.out"
     )
-    f = open(fpth, "w")
-    for i in range(diff.shape[0]):
-        if i == 0:
-            line = f"{'TIME':>10s}"
-            for idx, key in enumerate(bud_lst):
-                line += f"{key + '_LST':>25s}"
-                line += f"{key + '_CBC':>25s}"
-                line += f"{key + '_DIF':>25s}"
+    with open(fpth, "w") as f:
+        for i in range(diff.shape[0]):
+            if i == 0:
+                line = f"{'TIME':>10s}"
+                for key in bud_lst:
+                    line += f"{key + '_LST':>25s}"
+                    line += f"{key + '_CBC':>25s}"
+                    line += f"{key + '_DIF':>25s}"
+                f.write(line + "\n")
+            line = f"{d['totim'][i]:10g}"
+            for ii, key in enumerate(bud_lst):
+                line += f"{d0[key][i]:25g}"
+                line += f"{d[key][i]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
-        line = f"{d['totim'][i]:10g}"
-        for idx, key in enumerate(bud_lst):
-            line += f"{d0[key][i]:25g}"
-            line += f"{d[key][i]:25g}"
-            line += f"{diff[i, idx]:25g}"
-        f.write(line + "\n")
-    f.close()
 
     dtol = 1e-6
 
     if diffmax > budtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
-@pytest.mark.parametrize("name", ex)
-def test_mf6model(name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, 0, str(function_tmpdir))
-    test.run(
-        TestSimulation(name=name, exe_dict=targets, exfunc=eval_sub, idxsim=0),
-        str(function_tmpdir),
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_sub01_elastic.py b/autotest/test_gwf_csub_sub01_elastic.py
index 815910827b4..05a59a2045a 100644
--- a/autotest/test_gwf_csub_sub01_elastic.py
+++ b/autotest/test_gwf_csub_sub01_elastic.py
@@ -3,14 +3,14 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
+cases = ["csub_sub01_elasa"]
 cmppth = "mf6"
 paktest = "csub"
 dtol = 1e-3
 budtol = 1e-2
-ex = ["csub_sub01_elasa"]
 ndcell = [19]
 
 # static model data
@@ -24,13 +24,13 @@
 
 # temporal discretization
 nper = 1
-perlen = [1000.0 for i in range(nper)]
-nstp = [100 for i in range(nper)]
-tsmult = [1.05 for i in range(nper)]
-steady = [False for i in range(nper)]
+perlen = [1000.0 for _ in range(nper)]
+nstp = [100 for _ in range(nper)]
+tsmult = [1.05 for _ in range(nper)]
+steady = [False for _ in range(nper)]
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 strt = 0.0
 strt6 = 1.0
@@ -90,7 +90,7 @@
 
 
 def build_mf6(idx, ws, newton=None):
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
     sim = flopy.mf6.MFSimulation(
@@ -176,28 +176,23 @@ def build_mf6(idx, ws, newton=None):
     return sim
 
 
-def build_model(idx, dir):
-    ws = dir
-    sim = build_mf6(idx, ws)
-
-    ws = os.path.join(ws, cmppth)
+def build_models(idx, test):
+    sim = build_mf6(idx, test.workspace)
+    ws = os.path.join(test.workspace, cmppth)
     mc = build_mf6(idx, ws, newton="NEWTON")
-
     return sim, mc
 
 
-def eval_sub(sim):
-    print("evaluating subsidence...")
-
+def check_output(idx, test):
     # MODFLOW 6 total compaction results
-    fpth = os.path.join(sim.simpath, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
         assert False, f'could not load data from "{fpth}"'
 
     # MODFLOW 6 with newton-raphson
-    fpth = os.path.join(sim.simpath, cmppth, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, cmppth, "csub_obs.csv")
     try:
         tci = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -216,42 +211,39 @@ def eval_sub(sim):
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.comp.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.comp.cmp.out"
     )
-    f = open(fpth, "w")
-    line = f"{'TOTIM':>15s}"
-    for tag in tc.dtype.names[1:]:
-        line += f" {f'{tag}_SK':>15s}"
-        line += f" {f'{tag}_SKIB':>15s}"
-        line += f" {f'{tag}_DIFF':>15s}"
-    f.write(line + "\n")
-    for i in range(diff.shape[0]):
-        line = f"{tc['time'][i]:15g}"
+    with open(fpth, "w") as f:
+        line = f"{'TOTIM':>15s}"
         for tag in tc.dtype.names[1:]:
-            line += f" {tc[tag][i]:15g}"
-            line += f" {tci[tag][i]:15g}"
-            line += f" {tc[tag][i] - tci[tag][i]:15g}"
+            line += f" {f'{tag}_SK':>15s}"
+            line += f" {f'{tag}_SKIB':>15s}"
+            line += f" {f'{tag}_DIFF':>15s}"
         f.write(line + "\n")
-    f.close()
+        for i in range(diff.shape[0]):
+            line = f"{tc['time'][i]:15g}"
+            for tag in tc.dtype.names[1:]:
+                line += f" {tc[tag][i]:15g}"
+                line += f" {tci[tag][i]:15g}"
+                line += f" {tc[tag][i] - tci[tag][i]:15g}"
+            f.write(line + "\n")
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
     # compare budgets
-    cbc_compare(sim)
-
-    return
+    cbc_compare(test)
 
 
 # compare cbc and lst budgets
-def cbc_compare(sim):
+def cbc_compare(test):
     # open cbc file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
     cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # build list of cbc data to retrieve
@@ -268,7 +260,7 @@ def cbc_compare(sim):
             bud_lst.append(f"{t}_OUT")
 
     # get results from listing file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
     budl = flopy.utils.Mf6ListBudget(fpth)
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
@@ -281,7 +273,7 @@ def cbc_compare(sim):
     # get data from cbc dile
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -299,60 +291,56 @@ def cbc_compare(sim):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, key in enumerate(bud_lst):
-        diff[:, idx] = d0[key] - d[key]
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
     diffmax = np.abs(diff).max()
     msg = f"maximum absolute total-budget difference ({diffmax}) "
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.bud.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.bud.cmp.out"
     )
-    f = open(fpth, "w")
-    for i in range(diff.shape[0]):
-        if i == 0:
-            line = f"{'TIME':>10s}"
-            for idx, key in enumerate(bud_lst):
-                line += f"{key + '_LST':>25s}"
-                line += f"{key + '_CBC':>25s}"
-                line += f"{key + '_DIF':>25s}"
+    with open(fpth, "w") as f:
+        for i in range(diff.shape[0]):
+            if i == 0:
+                line = f"{'TIME':>10s}"
+                for key in bud_lst:
+                    line += f"{key + '_LST':>25s}"
+                    line += f"{key + '_CBC':>25s}"
+                    line += f"{key + '_DIF':>25s}"
+                f.write(line + "\n")
+            line = f"{d['totim'][i]:10g}"
+            for ii, key in enumerate(bud_lst):
+                line += f"{d0[key][i]:25g}"
+                line += f"{d[key][i]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
-        line = f"{d['totim'][i]:10g}"
-        for idx, key in enumerate(bud_lst):
-            line += f"{d0[key][i]:25g}"
-            line += f"{d[key][i]:25g}"
-            line += f"{diff[i, idx]:25g}"
-        f.write(line + "\n")
-    f.close()
 
     if diffmax > budtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_sub, idxsim=idx
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_sub01_pch.py b/autotest/test_gwf_csub_sub01_pch.py
index b4b12c81e5b..970e665a3c7 100644
--- a/autotest/test_gwf_csub_sub01_pch.py
+++ b/autotest/test_gwf_csub_sub01_pch.py
@@ -3,14 +3,14 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
+cases = ["csub_sub01_pch"]
 paktest = "csub"
 budtol = 1e-2
 compdir = "mf6"
-ex = ["csub_sub01_pch"]
-ndcell = [19] * len(ex)
+ndcell = [19] * len(cases)
 
 # static model data
 # spatial discretization
@@ -23,10 +23,10 @@
 
 # temporal discretization
 nper = 1
-perlen = [1000.0 for i in range(nper)]
-nstp = [100 for i in range(nper)]
-tsmult = [1.05 for i in range(nper)]
-steady = [False for i in range(nper)]
+perlen = [1000.0 for _ in range(nper)]
+nstp = [100 for _ in range(nper)]
+tsmult = [1.05 for _ in range(nper)]
+steady = [False for _ in range(nper)]
 
 strt = 0.0
 strt6 = 1.0
@@ -41,8 +41,8 @@
 hclose, rclose, relax = 1e-12, 1e-6, 0.97
 
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 ib = 1
 
@@ -69,18 +69,18 @@
 thick = [1.0]
 
 
-def build_model(idx, dir):
-    sim = get_model(idx, dir, pch=True)
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace, pch=True)
 
     # build MODFLOW-6 with constant material properties
-    pth = os.path.join(dir, compdir)
+    pth = os.path.join(test.workspace, compdir)
     mc = get_model(idx, pth)
 
     return sim, mc
 
 
 def get_model(idx, dir, pch=None):
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
     ws = dir
@@ -221,18 +221,16 @@ def get_model(idx, dir, pch=None):
     return sim
 
 
-def eval_sub(sim):
-    print("evaluating subsidence...")
-
+def check_output(idx, test):
     # MODFLOW 6 compaction results
-    fpth = os.path.join(sim.simpath, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
         assert False, f'could not load data from "{fpth}"'
 
     # MODFLOW 6 base compaction results
-    fpth = os.path.join(sim.simpath, compdir, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, compdir, "csub_obs.csv")
     try:
         tcb = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -246,38 +244,37 @@ def eval_sub(sim):
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.comp.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.comp.cmp.out"
     )
-    f = open(fpth, "w")
-    line = f"{'TOTIM':>15s}"
-    line += f" {'CSUB':>15s}"
-    line += f" {'MF':>15s}"
-    line += f" {'DIFF':>15s}"
-    f.write(line + "\n")
-    for i in range(diff.shape[0]):
-        line = f"{tc['time'][i]:15g}"
-        line += f" {tc['TCOMP'][i]:15g}"
-        line += f" {tcb['TCOMP'][i]:15g}"
-        line += f" {diff[i]:15g}"
+    with open(fpth, "w") as f:
+        line = f"{'TOTIM':>15s}"
+        line += f" {'CSUB':>15s}"
+        line += f" {'MF':>15s}"
+        line += f" {'DIFF':>15s}"
         f.write(line + "\n")
-    f.close()
+        for i in range(diff.shape[0]):
+            line = f"{tc['time'][i]:15g}"
+            line += f" {tc['TCOMP'][i]:15g}"
+            line += f" {tcb['TCOMP'][i]:15g}"
+            line += f" {diff[i]:15g}"
+            f.write(line + "\n")
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol:15.7g}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
     # compare budgets
-    cbc_compare(sim)
+    cbc_compare(test)
 
 
 # compare cbc and lst budgets
-def cbc_compare(sim):
+def cbc_compare(test):
     # open cbc file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
     cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # build list of cbc data to retrieve
@@ -294,7 +291,7 @@ def cbc_compare(sim):
             bud_lst.append(f"{t}_OUT")
 
     # get results from listing file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
     budl = flopy.utils.Mf6ListBudget(fpth)
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
@@ -307,7 +304,7 @@ def cbc_compare(sim):
     # get data from cbc dile
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -325,62 +322,58 @@ def cbc_compare(sim):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, key in enumerate(bud_lst):
-        diff[:, idx] = d0[key] - d[key]
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
     diffmax = np.abs(diff).max()
     msg = f"maximum absolute total-budget difference ({diffmax}) "
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.bud.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.bud.cmp.out"
     )
-    f = open(fpth, "w")
-    for i in range(diff.shape[0]):
-        if i == 0:
-            line = f"{'TIME':>10s}"
-            for idx, key in enumerate(bud_lst):
-                line += f"{key + '_LST':>25s}"
-                line += f"{key + '_CBC':>25s}"
-                line += f"{key + '_DIF':>25s}"
+    with open(fpth, "w") as f:
+        for i in range(diff.shape[0]):
+            if i == 0:
+                line = f"{'TIME':>10s}"
+                for key in bud_lst:
+                    line += f"{key + '_LST':>25s}"
+                    line += f"{key + '_CBC':>25s}"
+                    line += f"{key + '_DIF':>25s}"
+                f.write(line + "\n")
+            line = f"{d['totim'][i]:10g}"
+            for ii, key in enumerate(bud_lst):
+                line += f"{d0[key][i]:25g}"
+                line += f"{d[key][i]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
-        line = f"{d['totim'][i]:10g}"
-        for idx, key in enumerate(bud_lst):
-            line += f"{d0[key][i]:25g}"
-            line += f"{d[key][i]:25g}"
-            line += f"{diff[i, idx]:25g}"
-        f.write(line + "\n")
-    f.close()
 
     dtol = 1e-6
 
     if diffmax > budtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_sub, idxsim=idx
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_sub02.py b/autotest/test_gwf_csub_sub02.py
index 7596dfc1875..07985c835d5 100644
--- a/autotest/test_gwf_csub_sub02.py
+++ b/autotest/test_gwf_csub_sub02.py
@@ -2,10 +2,10 @@
 
 import flopy
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = [
+cases = [
     "csub_sub02a",
     "csub_sub02b",
     "csub_sub02c",
@@ -23,10 +23,10 @@
 # static model data
 nlay, nrow, ncol = 1, 1, 1
 nper = 10
-perlen = [182.625 for i in range(nper)]
-nstp = [10 for i in range(nper)]
-tsmult = [1.05 for i in range(nper)]
-steady = [False for i in range(nper)]
+perlen = [182.625 for _ in range(nper)]
+nstp = [10 for _ in range(nper)]
+tsmult = [1.05 for _ in range(nper)]
+steady = [False for _ in range(nper)]
 delr, delc = 1000.0, 1000.0
 top = -100.0
 botm = [-600.0]
@@ -41,8 +41,8 @@
 hclose, rclose, relax = 1e-6, 1e-6, 0.97
 
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 ib = 1
 
@@ -76,7 +76,7 @@
 
 
 def get_model(idx, ws):
-    name = ex[idx]
+    name = cases[idx]
     ss = 1.14e-3
     sc6 = True
     if not storagecoeff[idx]:
@@ -200,23 +200,20 @@ def get_model(idx, ws):
     return sim
 
 
-def build_model(idx, dir):
-    ws = dir
-    sim = get_model(idx, ws)
-
-    ws = os.path.join(dir, cmppth)
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace)
+    ws = os.path.join(test.workspace, cmppth)
     mc = get_model(idx, ws)
     return sim, mc
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(name=name, exe_dict=targets, mf6_regression=True),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        targets=targets,
+        compare="mf6_regression",
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_sub03.py b/autotest/test_gwf_csub_sub03.py
index dbb848c2b3c..cdd41d0b6ea 100644
--- a/autotest/test_gwf_csub_sub03.py
+++ b/autotest/test_gwf_csub_sub03.py
@@ -3,11 +3,11 @@
 import flopy
 import numpy as np
 import pytest
+
 from conftest import project_root_path
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["csub_sub03a", "csub_sub03b"]
+cases = ["csub_sub03a", "csub_sub03b"]
 cmppth = "mf6_regression"
 cvopt = [None, None, None]
 constantcv = [True, True]
@@ -25,10 +25,10 @@
 # static model data
 nlay, nrow, ncol = 3, 10, 10
 nper = 31
-perlen = [1.0] + [365.2500000 for i in range(nper - 1)]
-nstp = [1] + [6 for i in range(nper - 1)]
-tsmult = [1.0] + [1.3 for i in range(nper - 1)]
-steady = [True] + [False for i in range(nper - 1)]
+perlen = [1.0] + [365.2500000 for _ in range(nper - 1)]
+nstp = [1] + [6 for _ in range(nper - 1)]
+tsmult = [1.0] + [1.3 for _ in range(nper - 1)]
+steady = [True] + [False for _ in range(nper - 1)]
 delr, delc = 1000.0, 2000.0
 top = 0.0
 botm = [-100, -150.0, -350.0]
@@ -59,8 +59,8 @@
 hclose, rclose, relax = 1e-9, 1e-6, 1.0
 
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 # all cells are active
 ib = 1
@@ -140,7 +140,7 @@
 
 # SUB package problem 3
 def get_model(idx, ws):
-    name = ex[idx]
+    name = cases[idx]
     # ibc packagedata container counter
     sub6 = []
     ibcno = 0
@@ -344,28 +344,25 @@ def get_model(idx, ws):
     return sim
 
 
-def build_model(idx, dir):
-    ws = dir
-    sim = get_model(idx, ws)
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace)
 
-    ws = os.path.join(dir, cmppth)
+    ws = os.path.join(test.workspace, cmppth)
     mc = get_model(idx, ws)
 
     return sim, mc
 
 
-def eval_comp(sim):
-    print("evaluating compaction...")
-
+def check_output(idx, test):
     # MODFLOW 6 total compaction results
-    fpth = os.path.join(sim.simpath, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
         assert False, f'could not load data from "{fpth}"'
 
     # Comparision total compaction results
-    fpth = os.path.join(sim.simpath, cmppth, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, cmppth, "csub_obs.csv")
     try:
         tc0 = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -377,15 +374,15 @@ def eval_comp(sim):
     msg = f"maximum absolute total-compaction difference ({diffmax}) "
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
     # get results from listing file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
     budl = flopy.utils.Mf6ListBudget(fpth)
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
@@ -397,11 +394,11 @@ def eval_comp(sim):
     d = np.recarray(nbud, dtype=dtype)
     for key in bud_lst:
         d[key] = 0.0
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
     cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -411,44 +408,39 @@ def eval_comp(sim):
                     qout -= vv
                 else:
                     qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, key in enumerate(bud_lst):
-        diff[:, idx] = d0[key] - d[key]
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
     diffmax = np.abs(diff).max()
     msg = f"maximum absolute total-budget difference ({diffmax}) "
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_comp,
-            htol=htol[idx],
-            mf6_regression=True,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
+        htol=htol[idx],
+        compare="mf6_regression",
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_subwt01.py b/autotest/test_gwf_csub_subwt01.py
index aad1e15e503..a1ff03b8aa7 100644
--- a/autotest/test_gwf_csub_subwt01.py
+++ b/autotest/test_gwf_csub_subwt01.py
@@ -3,12 +3,12 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["csub_subwt01a", "csub_subwt01b", "csub_subwt01c", "csub_subwt01d"]
+cases = ["csub_subwt01a", "csub_subwt01b", "csub_subwt01c", "csub_subwt01d"]
 cmppth = "mf6_regression"
-htol = [None for n in ex]
+htol = [None for _ in cases]
 dtol = 1e-3
 budtol = 1e-2
 paktest = "csub"
@@ -62,8 +62,8 @@
 fluxtol = rclose
 
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 # this used to work
 # ib = np.zeros((nlay, nrow, ncol), dtype=int)
@@ -119,7 +119,7 @@
 
 
 def get_model(idx, ws):
-    name = ex[idx]
+    name = cases[idx]
     sim = flopy.mf6.MFSimulation(
         sim_name=name,
         memory_print_option="all",
@@ -238,24 +238,20 @@ def get_model(idx, ws):
     return sim
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     # build MODFLOW 6 files
-    ws = dir
-    sim = get_model(idx, ws)
+    sim = get_model(idx, test.workspace)
 
     # build comparision files
-    ws = os.path.join(dir, cmppth)
+    ws = os.path.join(test.workspace, cmppth)
     mc = get_model(idx, ws)
 
     return sim, mc
 
 
-def eval_comp(sim):
-
-    print("evaluating compaction...")
+def check_output(idx, test):
     # MODFLOW 6 total compaction results
-    fpth = os.path.join(sim.simpath, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -263,7 +259,7 @@ def eval_comp(sim):
 
     # Comparision total compaction results
     cpth = cmppth
-    fpth = os.path.join(sim.simpath, cpth, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, cpth, "csub_obs.csv")
     try:
         tc0 = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -277,41 +273,37 @@ def eval_comp(sim):
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.comp.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.comp.cmp.out"
     )
-    f = open(fpth, "w")
-    line = f"{'TOTIM':>15s}"
-    line += f" {'CSUB':>15s}"
-    line += f" {'MF':>15s}"
-    line += f" {'DIFF':>15s}"
-    f.write(line + "\n")
-    for i in range(diff.shape[0]):
-        line = f"{tc0['time'][i]:15g}"
-        line += f" {tc[loctag][i]:15g}"
-        line += f" {tc0[loctag][i]:15g}"
-        line += f" {diff[i]:15g}"
+    with open(fpth, "w") as f:
+        line = f"{'TOTIM':>15s}"
+        line += f" {'CSUB':>15s}"
+        line += f" {'MF':>15s}"
+        line += f" {'DIFF':>15s}"
         f.write(line + "\n")
-    f.close()
+        for i in range(diff.shape[0]):
+            line = f"{tc0['time'][i]:15g}"
+            line += f" {tc[loctag][i]:15g}"
+            line += f" {tc0[loctag][i]:15g}"
+            line += f" {diff[i]:15g}"
+            f.write(line + "\n")
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
     # compare budgets
-    cbc_compare(sim)
-
-    return
+    cbc_compare(test)
 
 
 # compare cbc and lst budgets
-def cbc_compare(sim):
-    print("evaluating cbc and budget...")
+def cbc_compare(test):
     # open cbc file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
     cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # build list of cbc data to retrieve
@@ -328,7 +320,7 @@ def cbc_compare(sim):
             bud_lst.append(f"{t}_OUT")
 
     # get results from listing file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
     budl = flopy.utils.Mf6ListBudget(fpth)
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
@@ -341,7 +333,7 @@ def cbc_compare(sim):
     # get data from cbc dile
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -359,65 +351,59 @@ def cbc_compare(sim):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, key in enumerate(bud_lst):
-        diff[:, idx] = d0[key] - d[key]
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
     diffmax = np.abs(diff).max()
     msg = f"maximum absolute total-budget difference ({diffmax}) "
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.bud.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.bud.cmp.out"
     )
-    f = open(fpth, "w")
-    for i in range(diff.shape[0]):
-        if i == 0:
-            line = f"{'TIME':>10s}"
-            for idx, key in enumerate(bud_lst):
-                line += f"{key + '_LST':>25s}"
-                line += f"{key + '_CBC':>25s}"
-                line += f"{key + '_DIF':>25s}"
+    with open(fpth, "w") as f:
+        for i in range(diff.shape[0]):
+            if i == 0:
+                line = f"{'TIME':>10s}"
+                for key in bud_lst:
+                    line += f"{key + '_LST':>25s}"
+                    line += f"{key + '_CBC':>25s}"
+                    line += f"{key + '_DIF':>25s}"
+                f.write(line + "\n")
+            line = f"{d['totim'][i]:10g}"
+            for ii, key in enumerate(bud_lst):
+                line += f"{d0[key][i]:25g}"
+                line += f"{d[key][i]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
-        line = f"{d['totim'][i]:10g}"
-        for idx, key in enumerate(bud_lst):
-            line += f"{d0[key][i]:25g}"
-            line += f"{d[key][i]:25g}"
-            line += f"{diff[i, idx]:25g}"
-        f.write(line + "\n")
-    f.close()
 
     if diffmax > budtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_comp,
-            htol=htol[idx],
-            mf6_regression=True,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
+        htol=htol[idx],
+        compare="mf6_regression",
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_subwt02.py b/autotest/test_gwf_csub_subwt02.py
index bf9068e4172..877e5474d4c 100644
--- a/autotest/test_gwf_csub_subwt02.py
+++ b/autotest/test_gwf_csub_subwt02.py
@@ -3,11 +3,11 @@
 import flopy
 import numpy as np
 import pytest
+
 from conftest import project_root_path
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["csub_subwt02a", "csub_subwt02b", "csub_subwt02c", "csub_subwt02d"]
+cases = ["csub_subwt02a", "csub_subwt02b", "csub_subwt02c", "csub_subwt02d"]
 timeseries = [True, False, True, False]
 cmppth = "mf6_regression"
 htol = [None, None, None, None]
@@ -183,7 +183,7 @@
 # beta = 4.65120000e-10
 gammaw = 9806.65000000
 sw = beta * gammaw * theta
-ss = [sw for k in range(nlay)]
+ss = [sw for _ in range(nlay)]
 
 swt6 = []
 ibcno = 0
@@ -216,7 +216,7 @@
 
 
 def get_model(idx, ws):
-    name = ex[idx]
+    name = cases[idx]
 
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
@@ -407,23 +407,21 @@ def get_model(idx, ws):
     return sim
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = get_model(idx, ws)
 
     # build comparision files
-    ws = os.path.join(dir, cmppth)
+    ws = os.path.join(test.workspace, cmppth)
     mc = get_model(idx, ws)
 
     return sim, mc
 
 
-def eval_comp(sim):
-    print("evaluating compaction...")
+def check_output(idx, test):
     # MODFLOW 6 total compaction results
-    fpth = os.path.join(sim.simpath, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -431,7 +429,7 @@ def eval_comp(sim):
 
     # comparision total compaction results
     cpth = cmppth
-    fpth = os.path.join(sim.simpath, cmppth, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, cmppth, "csub_obs.csv")
     try:
         tc0 = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -445,7 +443,7 @@ def eval_comp(sim):
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.comp.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.comp.cmp.out"
     )
     f = open(fpth, "w")
     line = f"{'TOTIM':>15s}"
@@ -462,24 +460,23 @@ def eval_comp(sim):
     f.close()
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
     # compare budgets
-    cbc_compare(sim)
+    cbc_compare(test)
 
     return
 
 
 # compare cbc and lst budgets
-def cbc_compare(sim):
-    print("evaluating cbc and budget...")
+def cbc_compare(test):
     # open cbc file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
     cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # build list of cbc data to retrieve
@@ -496,7 +493,7 @@ def cbc_compare(sim):
             bud_lst.append(f"{t}_OUT")
 
     # get results from listing file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
     budl = flopy.utils.Mf6ListBudget(fpth)
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
@@ -509,7 +506,7 @@ def cbc_compare(sim):
     # get data from cbc dile
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -527,65 +524,59 @@ def cbc_compare(sim):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, key in enumerate(bud_lst):
-        diff[:, idx] = d0[key] - d[key]
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
     diffmax = np.abs(diff).max()
     msg = f"maximum absolute total-budget difference ({diffmax}) "
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.bud.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.bud.cmp.out"
     )
-    f = open(fpth, "w")
-    for i in range(diff.shape[0]):
-        if i == 0:
-            line = f"{'TIME':>10s}"
-            for idx, key in enumerate(bud_lst):
-                line += f"{key + '_LST':>25s}"
-                line += f"{key + '_CBC':>25s}"
-                line += f"{key + '_DIF':>25s}"
+    with open(fpth, "w") as f:
+        for i in range(diff.shape[0]):
+            if i == 0:
+                line = f"{'TIME':>10s}"
+                for key in bud_lst:
+                    line += f"{key + '_LST':>25s}"
+                    line += f"{key + '_CBC':>25s}"
+                    line += f"{key + '_DIF':>25s}"
+                f.write(line + "\n")
+            line = f"{d['totim'][i]:10g}"
+            for ii, key in enumerate(bud_lst):
+                line += f"{d0[key][i]:25g}"
+                line += f"{d[key][i]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
-        line = f"{d['totim'][i]:10g}"
-        for idx, key in enumerate(bud_lst):
-            line += f"{d0[key][i]:25g}"
-            line += f"{d[key][i]:25g}"
-            line += f"{diff[i, idx]:25g}"
-        f.write(line + "\n")
-    f.close()
 
     if diffmax > budtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_comp,
-            htol=htol[idx],
-            mf6_regression=True,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
+        htol=htol[idx],
+        compare="mf6_regression",
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_subwt03.py b/autotest/test_gwf_csub_subwt03.py
index abe743ca558..14c56e899d3 100644
--- a/autotest/test_gwf_csub_subwt03.py
+++ b/autotest/test_gwf_csub_subwt03.py
@@ -3,12 +3,12 @@
 import flopy
 import numpy as np
 import pytest
+
 from conftest import project_root_path
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["csub_subwt03a", "csub_subwt03b", "csub_subwt03c", "csub_subwt03d"]
-nex = len(ex)
+cases = ["csub_subwt03a", "csub_subwt03b", "csub_subwt03c", "csub_subwt03d"]
+nex = len(cases)
 cmppth = "mf6"
 htol = None  # 0.1
 dtol = 1e-3
@@ -29,8 +29,8 @@
 tsmult = [1.0, 1.0, 1.0]
 steady = [True, False, False]
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 # spatial discretization
 nlay, nrow, ncol = 4, ib0.shape[0], ib0.shape[1]
@@ -57,18 +57,18 @@
 wnlays = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 3]
 wnrows = [0, 1, 1, 1, 2, 3, 4, 4, 5, 6, 13, 13, 15, 15, 16, 17, 17, 18, 8, 11]
 wncols = [7, 4, 7, 11, 3, 11, 2, 12, 13, 1, 1, 13, 2, 12, 12, 3, 11, 6, 9, 6]
-wrates0 = [2.2e3 for n in range(18)] + [0.0, 0.0]
-wrates1 = [2.2e3 for n in range(18)] + [-7.2e04, -7.2e04]
+wrates0 = [2.2e3 for _ in range(18)] + [0.0, 0.0]
+wrates1 = [2.2e3 for _ in range(18)] + [-7.2e04, -7.2e04]
 
 w0 = []
 w1 = []
 ws0 = []
 ws1 = []
-for idx, (k, i, j) in enumerate(zip(wnlays, wnrows, wncols)):
-    w0.append((k, i, j, wrates0[idx]))
-    w1.append((k, i, j, wrates1[idx]))
-    ws0.append(((k, i, j), wrates0[idx]))
-    ws1.append(((k, i, j), wrates1[idx]))
+for i, (k, i, j) in enumerate(zip(wnlays, wnrows, wncols)):
+    w0.append((k, i, j, wrates0[i]))
+    w1.append((k, i, j, wrates1[i]))
+    ws0.append(((k, i, j), wrates0[i]))
+    ws1.append(((k, i, j), wrates1[i]))
 wd = {0: w0, 1: w1, 2: w0}
 wd6 = {0: ws0, 1: ws1, 2: ws0}
 
@@ -202,11 +202,11 @@ def get_interbed(headbased=False, delay=False):
     return swt6
 
 
-def build_model(idx, dir):
-    sim = build_mf6(idx, dir)
+def build_models(idx, test):
+    sim = build_mf6(idx, test.workspace)
 
     # build mf6 with interbeds
-    wsc = os.path.join(dir, "mf6")
+    wsc = os.path.join(test.workspace, "mf6")
     mc = build_mf6(idx, wsc, interbed=True)
 
     return sim, mc
@@ -214,8 +214,7 @@ def build_model(idx, dir):
 
 # build MODFLOW 6 files
 def build_mf6(idx, ws, interbed=False):
-
-    name = ex[idx]
+    name = cases[idx]
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -353,18 +352,16 @@ def build_mf6(idx, ws, interbed=False):
     return sim
 
 
-def eval_comp(sim):
-    print("evaluating compaction...")
-
+def check_output(idx, test):
     # MODFLOW 6 without interbeds
-    fpth = os.path.join(sim.simpath, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
         assert False, f'could not load data from "{fpth}"'
 
     # MODFLOW 6 with interbeds
-    fpth = os.path.join(sim.simpath, cmppth, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, cmppth, "csub_obs.csv")
     try:
         tci = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -383,41 +380,39 @@ def eval_comp(sim):
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.comp.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.comp.cmp.out"
     )
-    f = open(fpth, "w")
-    line = f"{'TOTIM':>15s}"
-    for tag in tc.dtype.names[1:]:
-        line += f" {f'{tag}_SK':>15s}"
-        line += f" {f'{tag}_SKIB':>15s}"
-        line += f" {f'{tag}_DIFF':>15s}"
-    f.write(line + "\n")
-    for i in range(diff.shape[0]):
-        line = f"{tc['time'][i]:15g}"
+    with open(fpth, "w") as f:
+        line = f"{'TOTIM':>15s}"
         for tag in tc.dtype.names[1:]:
-            line += f" {tc[tag][i]:15g}"
-            line += f" {tci[tag][i]:15g}"
-            line += f" {tc[tag][i] - tci[tag][i]:15g}"
+            line += f" {f'{tag}_SK':>15s}"
+            line += f" {f'{tag}_SKIB':>15s}"
+            line += f" {f'{tag}_DIFF':>15s}"
         f.write(line + "\n")
-    f.close()
+        for i in range(diff.shape[0]):
+            line = f"{tc['time'][i]:15g}"
+            for tag in tc.dtype.names[1:]:
+                line += f" {tc[tag][i]:15g}"
+                line += f" {tci[tag][i]:15g}"
+                line += f" {tc[tag][i] - tci[tag][i]:15g}"
+            f.write(line + "\n")
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
     # compare budgets
-    cbc_compare(sim)
+    cbc_compare(test)
 
 
 # compare cbc and lst budgets
-def cbc_compare(sim):
-    print("evaluating cbc and budget...")
+def cbc_compare(test):
     # open cbc file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
     cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # build list of cbc data to retrieve
@@ -434,7 +429,7 @@ def cbc_compare(sim):
             bud_lst.append(f"{t}_OUT")
 
     # get results from listing file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
     budl = flopy.utils.Mf6ListBudget(fpth)
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
@@ -447,7 +442,7 @@ def cbc_compare(sim):
     # get data from cbc dile
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -465,66 +460,58 @@ def cbc_compare(sim):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, key in enumerate(bud_lst):
-        diff[:, idx] = d0[key] - d[key]
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
     diffmax = np.abs(diff).max()
     msg = f"maximum absolute total-budget difference ({diffmax}) "
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.bud.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.bud.cmp.out"
     )
-    f = open(fpth, "w")
-    for i in range(diff.shape[0]):
-        if i == 0:
-            line = f"{'TIME':>10s}"
-            for idx, key in enumerate(bud_lst):
-                line += f"{key + '_LST':>25s}"
-                line += f"{key + '_CBC':>25s}"
-                line += f"{key + '_DIF':>25s}"
+    with open(fpth, "w") as f:
+        for i in range(diff.shape[0]):
+            if i == 0:
+                line = f"{'TIME':>10s}"
+                for key in bud_lst:
+                    line += f"{key + '_LST':>25s}"
+                    line += f"{key + '_CBC':>25s}"
+                    line += f"{key + '_DIF':>25s}"
+                f.write(line + "\n")
+            line = f"{d['totim'][i]:10g}"
+            for ii, key in enumerate(bud_lst):
+                line += f"{d0[key][i]:25g}"
+                line += f"{d[key][i]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
-        line = f"{d['totim'][i]:10g}"
-        for idx, key in enumerate(bud_lst):
-            line += f"{d0[key][i]:25g}"
-            line += f"{d[key][i]:25g}"
-            line += f"{diff[i, idx]:25g}"
-        f.write(line + "\n")
-    f.close()
 
     if diffmax > budtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_comp,
-            cmp_verbose=False,
-            htol=htol,
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        htol=htol,
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_wc01.py b/autotest/test_gwf_csub_wc01.py
index 1ec2bd2d69f..516bd661fb1 100644
--- a/autotest/test_gwf_csub_wc01.py
+++ b/autotest/test_gwf_csub_wc01.py
@@ -3,11 +3,11 @@
 import flopy
 import numpy as np
 import pytest
+
 from conftest import project_root_path
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["csub_wc01a", "csub_wc02b"]
+cases = ["csub_wc01a", "csub_wc02b"]
 cmppth = "mf6"
 dtol = 1e-3
 budtol = 1e-2
@@ -25,8 +25,8 @@
 tsmult = [1.0, 1.0, 1.0]
 steady = [True, False, False]
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 # spatial discretization
 nlay, nrow, ncol = 4, ib0.shape[0], ib0.shape[1]
@@ -61,20 +61,20 @@
 wnlays = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 3]
 wnrows = [0, 1, 1, 1, 2, 3, 4, 4, 5, 6, 13, 13, 15, 15, 16, 17, 17, 18, 8, 11]
 wncols = [7, 4, 7, 11, 3, 11, 2, 12, 13, 1, 1, 13, 2, 12, 12, 3, 11, 6, 9, 6]
-wrates0 = [2.2e3 for n in range(18)] + [0.0, 0.0]
-wrates1 = [2.2e3 for n in range(18)] + [-7.2e03, -7.2e03]
+wrates0 = [2.2e3 for _ in range(18)] + [0.0, 0.0]
+wrates1 = [2.2e3 for _ in range(18)] + [-7.2e03, -7.2e03]
 
 w0 = []
 w1 = []
 ws0 = []
 ws1 = []
-for idx, (k, i, j) in enumerate(zip(wnlays, wnrows, wncols)):
+for i, (k, i, j) in enumerate(zip(wnlays, wnrows, wncols)):
     if ib0[i, j] < 1:
         continue
-    w0.append((k, i, j, wrates0[idx]))
-    w1.append((k, i, j, wrates1[idx]))
-    ws0.append(((k, i, j), wrates0[idx]))
-    ws1.append(((k, i, j), wrates1[idx]))
+    w0.append((k, i, j, wrates0[i]))
+    w1.append((k, i, j, wrates1[i]))
+    ws0.append(((k, i, j), wrates0[i]))
+    ws1.append(((k, i, j), wrates1[i]))
 wd = {0: w0, 1: w1, 2: w0}
 wd6 = {0: ws0, 1: ws1, 2: ws0}
 print(wd6)
@@ -211,11 +211,11 @@
 ]
 
 
-def build_model(idx, dir):
-    sim = build_mf6(idx, dir)
+def build_models(idx, test):
+    sim = build_mf6(idx, test.workspace)
 
     # build mf6 with interbeds
-    wsc = os.path.join(dir, "mf6")
+    wsc = os.path.join(test.workspace, "mf6")
     mc = build_mf6(idx, wsc, interbed=True)
 
     return sim, mc
@@ -223,8 +223,7 @@ def build_model(idx, dir):
 
 # build MODFLOW 6 files
 def build_mf6(idx, ws, interbed=False):
-
-    name = ex[idx]
+    name = cases[idx]
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -344,18 +343,16 @@ def build_mf6(idx, ws, interbed=False):
     return sim
 
 
-def eval_wcomp(sim):
-    print("evaluating compaction...")
-
+def check_output(idx, test):
     # MODFLOW 6 without interbeds water compressibility
-    fpth = os.path.join(sim.simpath, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
         assert False, f'could not load data from "{fpth}"'
 
     # MODFLOW 6 with interbeds water compressibility
-    fpth = os.path.join(sim.simpath, cmppth, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, cmppth, "csub_obs.csv")
     try:
         tci = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -377,41 +374,39 @@ def eval_wcomp(sim):
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.wcomp.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.wcomp.cmp.out"
     )
-    f = open(fpth, "w")
-    line = f"{'TOTIM':>15s}"
-    for tag in tc.dtype.names[1:]:
-        line += f" {f'{tag}_SK':>15s}"
-        line += f" {f'{tag}_SKIB':>15s}"
-        line += f" {f'{tag}_DIFF':>15s}"
-    f.write(line + "\n")
-    for i in range(diff.shape[0]):
-        line = f"{tc['time'][i]:15g}"
+    with open(fpth, "w") as f:
+        line = f"{'TOTIM':>15s}"
         for tag in tc.dtype.names[1:]:
-            line += f" {tc[tag][i]:15g}"
-            line += f" {tci[tag][i]:15g}"
-            line += f" {tc[tag][i] - tci[tag][i]:15g}"
+            line += f" {f'{tag}_SK':>15s}"
+            line += f" {f'{tag}_SKIB':>15s}"
+            line += f" {f'{tag}_DIFF':>15s}"
         f.write(line + "\n")
-    f.close()
+        for i in range(diff.shape[0]):
+            line = f"{tc['time'][i]:15g}"
+            for tag in tc.dtype.names[1:]:
+                line += f" {tc[tag][i]:15g}"
+                line += f" {tci[tag][i]:15g}"
+                line += f" {tc[tag][i] - tci[tag][i]:15g}"
+            f.write(line + "\n")
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
     # compare budgets
-    cbc_compare(sim)
+    cbc_compare(test)
 
 
 # compare cbc and lst budgets
-def cbc_compare(sim):
-    print("evaluating cbc and budget...")
+def cbc_compare(test):
     # open cbc file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
     cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # build list of cbc data to retrieve
@@ -428,7 +423,7 @@ def cbc_compare(sim):
             bud_lst.append(f"{t}_OUT")
 
     # get results from listing file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
     budl = flopy.utils.Mf6ListBudget(fpth)
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
@@ -441,7 +436,7 @@ def cbc_compare(sim):
     # get data from cbc dile
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -459,59 +454,57 @@ def cbc_compare(sim):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, key in enumerate(bud_lst):
-        diff[:, idx] = d0[key] - d[key]
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
     diffmax = np.abs(diff).max()
     msg = f"maximum absolute total-budget difference ({diffmax}) "
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.bud.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.bud.cmp.out"
     )
-    f = open(fpth, "w")
-    for i in range(diff.shape[0]):
-        if i == 0:
-            line = f"{'TIME':>10s}"
-            for idx, key in enumerate(bud_lst):
-                line += f"{key + '_LST':>25s}"
-                line += f"{key + '_CBC':>25s}"
-                line += f"{key + '_DIF':>25s}"
+    with open(fpth, "w") as f:
+        for i in range(diff.shape[0]):
+            if i == 0:
+                line = f"{'TIME':>10s}"
+                for key in bud_lst:
+                    line += f"{key + '_LST':>25s}"
+                    line += f"{key + '_CBC':>25s}"
+                    line += f"{key + '_DIF':>25s}"
+                f.write(line + "\n")
+            line = f"{d['totim'][i]:10g}"
+            for ii, key in enumerate(bud_lst):
+                line += f"{d0[key][i]:25g}"
+                line += f"{d[key][i]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
-        line = f"{d['totim'][i]:10g}"
-        for idx, key in enumerate(bud_lst):
-            line += f"{d0[key][i]:25g}"
-            line += f"{d[key][i]:25g}"
-            line += f"{diff[i, idx]:25g}"
-        f.write(line + "\n")
-    f.close()
 
     if diffmax > budtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(name=name, exe_dict=targets, exfunc=eval_wcomp),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_wtgeo.py b/autotest/test_gwf_csub_wtgeo.py
index 6f691516290..a0f50764e8d 100644
--- a/autotest/test_gwf_csub_wtgeo.py
+++ b/autotest/test_gwf_csub_wtgeo.py
@@ -3,10 +3,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = [
+cases = [
     "csub_wtgeoa",
     "csub_wtgeob",
     "csub_wtgeoc",
@@ -15,19 +15,19 @@
     "csub_wtgeof",
     "csub_wtgeog",
 ]
-constantcv = [True for idx in range(len(ex))]
+constantcv = [True for _ in range(len(cases))]
 cmppth = "mf6_regression"
-compare = [True for idx in range(len(ex))]
+compare = [True for _ in range(len(cases))]
 tops = [0.0, 0.0, 150.0, 0.0, 0.0, 150.0, 150.0]
 ump = [None, None, True, None, True, None, True]
 iump = [0, 0, 1, 0, 1, 0, 1]
-eslag = [True for idx in range(len(ex) - 2)] + 2 * [False]
+eslag = [True for _ in range(len(cases) - 2)] + 2 * [False]
 # eslag = [True, True, True, False, True, False, False]
 headformulation = [True, False, False, True, True, False, False]
 ndc = [None, None, None, 19, 19, 19, 19]
 delay = [False, False, False, True, True, True, True]
 # newton = ["", "", "", "", "", None, ""]
-newton = ["NEWTON" for idx in range(len(ex))]
+newton = ["NEWTON" for _ in range(len(cases))]
 
 htol = [None, None, None, 0.2, None, None, None]
 dtol = 1e-3
@@ -37,13 +37,13 @@
 # static model data
 # temporal discretization
 nper = 31
-perlen = [1.0] + [365.2500000 for i in range(nper - 1)]
-nstp = [1] + [6 for i in range(nper - 1)]
-tsmult = [1.0] + [1.3 for i in range(nper - 1)]
-steady = [True] + [False for i in range(nper - 1)]
+perlen = [1.0] + [365.2500000 for _ in range(nper - 1)]
+nstp = [1] + [6 for _ in range(nper - 1)]
+tsmult = [1.0] + [1.3 for _ in range(nper - 1)]
+steady = [True] + [False for _ in range(nper - 1)]
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 # spatial discretization data
 nlay, nrow, ncol = 3, 10, 10
@@ -161,7 +161,7 @@ def calc_stress(sgm0, sgs0, h, bt):
 
 
 def get_model(idx, ws):
-    name = ex[idx]
+    name = cases[idx]
 
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
@@ -472,25 +472,25 @@ def get_model(idx, ws):
     return sim
 
 
-def build_model(idx, dir):
-    sim = get_model(idx, dir)  # modflow6 files
-    mc = get_model(idx, os.path.join(dir, cmppth))  # build comparison files
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace)  # modflow6 files
+    mc = get_model(
+        idx, os.path.join(test.workspace, cmppth)
+    )  # build comparison files
     return sim, mc
 
 
-def eval_comp(sim):
-
-    if compare[sim.idxsim]:
-        print("evaluating compaction...")
+def check_output(idx, test):
+    if compare[idx]:
         # MODFLOW 6 total compaction results
-        fpth = os.path.join(sim.simpath, "csub_obs.csv")
+        fpth = os.path.join(test.workspace, "csub_obs.csv")
         try:
             tc = np.genfromtxt(fpth, names=True, delimiter=",")
         except:
             assert False, f'could not load data from "{fpth}"'
 
         # comparision total compaction results
-        fpth = os.path.join(sim.simpath, cmppth, "csub_obs.csv")
+        fpth = os.path.join(test.workspace, cmppth, "csub_obs.csv")
         try:
             tc0 = np.genfromtxt(fpth, names=True, delimiter=",")
         except:
@@ -503,40 +503,36 @@ def eval_comp(sim):
 
         # write summary
         fpth = os.path.join(
-            sim.simpath, f"{os.path.basename(sim.name)}.comp.cmp.out"
+            test.workspace, f"{os.path.basename(test.name)}.comp.cmp.out"
         )
-        f = open(fpth, "w")
-        line = f"{'TOTIM':>15s}"
-        line += f" {'CSUB':>15s}"
-        line += f" {'MF':>15s}"
-        line += f" {'DIFF':>15s}"
-        f.write(line + "\n")
-        for i in range(diff.shape[0]):
-            line = f"{tc0['time'][i]:15g}"
-            line += f" {tc['TCOMP3'][i]:15g}"
-            line += f" {tc0['TCOMP3'][i]:15g}"
-            line += f" {diff[i]:15g}"
+        with open(fpth, "w") as f:
+            line = f"{'TOTIM':>15s}"
+            line += f" {'CSUB':>15s}"
+            line += f" {'MF':>15s}"
+            line += f" {'DIFF':>15s}"
             f.write(line + "\n")
-        f.close()
+            for i in range(diff.shape[0]):
+                line = f"{tc0['time'][i]:15g}"
+                line += f" {tc['TCOMP3'][i]:15g}"
+                line += f" {tc0['TCOMP3'][i]:15g}"
+                line += f" {diff[i]:15g}"
+                f.write(line + "\n")
 
         if diffmax > dtol:
-            sim.success = False
+            test.success = False
             msg += f"exceeds {dtol}"
             assert diffmax < dtol, msg
         else:
-            sim.success = True
+            test.success = True
             print("    " + msg)
 
     # compare budgets
-    cbc_compare(sim)
+    cbc_compare(test)
 
-    return
 
-
-def cbc_compare(sim):
-    print("evaluating cbc and budget...")
+def cbc_compare(test):
     # open cbc file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
     cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # build list of cbc data to retrieve
@@ -553,7 +549,7 @@ def cbc_compare(sim):
             bud_lst.append(f"{t}_OUT")
 
     # get results from listing file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
     budl = flopy.utils.Mf6ListBudget(fpth)
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
@@ -566,7 +562,7 @@ def cbc_compare(sim):
     # get data from cbc dile
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -584,64 +580,60 @@ def cbc_compare(sim):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, key in enumerate(bud_lst):
-        diff[:, idx] = d0[key] - d[key]
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
     diffmax = np.abs(diff).max()
     msg = f"maximum absolute total-budget difference ({diffmax}) "
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.bud.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.bud.cmp.out"
     )
-    f = open(fpth, "w")
-    for i in range(diff.shape[0]):
-        if i == 0:
-            line = f"{'TIME':>10s}"
-            for idx, key in enumerate(bud_lst):
-                line += f"{key + '_LST':>25s}"
-                line += f"{key + '_CBC':>25s}"
-                line += f"{key + '_DIF':>25s}"
+    with open(fpth, "w") as f:
+        for i in range(diff.shape[0]):
+            if i == 0:
+                line = f"{'TIME':>10s}"
+                for key in bud_lst:
+                    line += f"{key + '_LST':>25s}"
+                    line += f"{key + '_CBC':>25s}"
+                    line += f"{key + '_DIF':>25s}"
+                f.write(line + "\n")
+            line = f"{d['totim'][i]:10g}"
+            for ii, key in enumerate(bud_lst):
+                line += f"{d0[key][i]:25g}"
+                line += f"{d[key][i]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
-        line = f"{d['totim'][i]:10g}"
-        for idx, key in enumerate(bud_lst):
-            line += f"{d0[key][i]:25g}"
-            line += f"{d[key][i]:25g}"
-            line += f"{diff[i, idx]:25g}"
-        f.write(line + "\n")
-    f.close()
 
     if diffmax > budtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize("idx, name", list(enumerate(ex)))
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_comp,
-            htol=htol[idx],
-            idxsim=idx,
-            mf6_regression=True,
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        htol=htol[idx],
+        compare="mf6_regression",
+        verbose=False,
     )
+    test.run()
diff --git a/autotest/test_gwf_csub_zdisp01.py b/autotest/test_gwf_csub_zdisp01.py
index f6ee90544e8..5b2f6091b3e 100644
--- a/autotest/test_gwf_csub_zdisp01.py
+++ b/autotest/test_gwf_csub_zdisp01.py
@@ -4,12 +4,12 @@
 import numpy as np
 import pytest
 from flopy.utils.compare import compare_heads
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["csub_zdisp01"]
+cases = ["csub_zdisp01"]
 cmppth = "mfnwt"
-htol = [None for idx in range(len(ex))]
+htol = [None for _ in range(len(cases))]
 dtol = 1e-3
 budtol = 1e-2
 bud_lst = [
@@ -30,14 +30,14 @@
 # static model data
 # temporal discretization
 nper = 31
-perlen = [1.0] + [365.2500000 for i in range(nper - 1)]
-nstp = [1] + [6 for i in range(nper - 1)]
-tsmult = [1.0] + [1.3 for i in range(nper - 1)]
-# tsmult = [1.0] + [1.0 for i in range(nper - 1)]
-steady = [True] + [False for i in range(nper - 1)]
+perlen = [1.0] + [365.2500000 for _ in range(nper - 1)]
+nstp = [1] + [6 for _ in range(nper - 1)]
+tsmult = [1.0] + [1.3 for _ in range(nper - 1)]
+# tsmult = [1.0] + [1.0 for _ in range(nper - 1)]
+steady = [True] + [False for _ in range(nper - 1)]
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 # spatial discretization data
 nlay, nrow, ncol = 3, 20, 20
@@ -192,11 +192,11 @@
 
 
 # variant SUB package problem 3
-def get_model(idx, dir):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -328,8 +328,10 @@ def get_model(idx, dir):
 
     # build MODFLOW-NWT files
     cpth = cmppth
-    ws = os.path.join(dir, cpth)
-    mc = flopy.modflow.Modflow(name, model_ws=ws, version=cpth)
+    ws = os.path.join(test.workspace, cpth)
+    mc = flopy.modflow.Modflow(
+        name, model_ws=ws, version=cpth, exe_name=test.targets["mfnwt"]
+    )
     dis = flopy.modflow.ModflowDis(
         mc,
         nlay=nlay,
@@ -393,27 +395,24 @@ def get_model(idx, dir):
         idroptol=0,
     )
 
-    sim.write_simulation()
-    mc.write_input()
-
     return sim, mc
 
 
-def eval_zdisplacement(sim):
-    print("evaluating z-displacement...")
-
+def check_output(idx, test):
     # MODFLOW 6 total compaction results
-    fpth = os.path.join(sim.simpath, "csub_obs.csv")
+    fpth = os.path.join(test.workspace, "csub_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
         assert False, f'could not load data from "{fpth}"'
 
     # MODFLOW-2005 total compaction results
-    fn = f"{os.path.basename(sim.name)}.total_comp.hds"
-    fpth = os.path.join(sim.simpath, "mfnwt", fn)
+    fn = f"{os.path.basename(test.name)}.total_comp.hds"
+    fpth = os.path.join(test.workspace, "mfnwt", fn)
     try:
-        sobj = flopy.utils.HeadFile(fpth, text="LAYER COMPACTION")
+        sobj = flopy.utils.HeadFile(
+            fpth, text="LAYER COMPACTION", verbose=False
+        )
         tc0 = sobj.get_ts((2, wrp[0], wcp[0]))
     except:
         assert False, f'could not load data from "{fpth}"'
@@ -424,15 +423,15 @@ def eval_zdisplacement(sim):
     msg = f"maximum absolute total-compaction difference ({diffmax}) "
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
     # get results from listing file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
     budl = flopy.utils.Mf6ListBudget(fpth)
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
@@ -451,11 +450,11 @@ def eval_zdisplacement(sim):
     d = np.recarray(nbud, dtype=dtype)
     for key in bud_lst:
         d[key] = 0.0
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
-    cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
+    cobj = flopy.utils.CellBudgetFile(fpth, precision="double", verbose=False)
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -473,60 +472,59 @@ def eval_zdisplacement(sim):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, key in enumerate(bud_lst):
-        diff[:, idx] = d0[key] - d[key]
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
     diffmax = np.abs(diff).max()
     msg = f"maximum absolute total-budget difference ({diffmax}) "
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.bud.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.bud.cmp.out"
     )
-    f = open(fpth, "w")
-    for i in range(diff.shape[0]):
-        if i == 0:
-            line = f"{'TIME':>10s}"
-            for idx, key in enumerate(bud_lst):
-                line += f"{key + '_LST':>25s}"
-                line += f"{key + '_CBC':>25s}"
-                line += f"{key + '_DIF':>25s}"
+    with open(fpth, "w") as f:
+        for i in range(diff.shape[0]):
+            if i == 0:
+                line = f"{'TIME':>10s}"
+                for key in bud_lst:
+                    line += f"{key + '_LST':>25s}"
+                    line += f"{key + '_CBC':>25s}"
+                    line += f"{key + '_DIF':>25s}"
+                f.write(line + "\n")
+            line = f"{d['totim'][i]:10g}"
+            for ii, key in enumerate(bud_lst):
+                line += f"{d0[key][i]:25g}"
+                line += f"{d[key][i]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
-        line = f"{d['totim'][i]:10g}"
-        for idx, key in enumerate(bud_lst):
-            line += f"{d0[key][i]:25g}"
-            line += f"{d[key][i]:25g}"
-            line += f"{diff[i, idx]:25g}"
-        f.write(line + "\n")
-    f.close()
 
     if diffmax > budtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
     # compare z-displacement data
     fpth1 = os.path.join(
-        sim.simpath,
-        f"{os.path.basename(sim.name)}.zdisplacement.gridbin",
+        test.workspace,
+        f"{os.path.basename(test.name)}.zdisplacement.gridbin",
     )
-    fpth2 = os.path.join(sim.simpath, cmppth, "csub_zdisp01.vert_disp.hds")
+    fpth2 = os.path.join(test.workspace, cmppth, "csub_zdisp01.vert_disp.hds")
     text1 = "CSUB-ZDISPLACE"
     text2 = "Z DISPLACEMENT"
     fout = os.path.join(
-        sim.simpath,
-        f"{os.path.basename(sim.name)}.z-displacement.bin.out",
+        test.workspace,
+        f"{os.path.basename(test.name)}.z-displacement.bin.out",
     )
     success_tst = compare_heads(
         None,
@@ -542,28 +540,22 @@ def eval_zdisplacement(sim):
     )
     msg = f"z-displacement comparison success = {success_tst}"
     if success_tst:
-        sim.success = True
+        test.success = True
         print(msg)
     else:
-        sim.success = False
+        test.success = False
         assert success_tst, msg
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    sim, mc = get_model(idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_zdisplacement,
-            htol=htol[idx],
-            idxsim=idx,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        htol=htol[idx],
     )
+    test.run()
diff --git a/autotest/test_gwf_disu.py b/autotest/test_gwf_disu.py
index 85880b95d82..c850d48f390 100644
--- a/autotest/test_gwf_disu.py
+++ b/autotest/test_gwf_disu.py
@@ -1,13 +1,26 @@
+"""
+Test of GWF DISU Package.  Use the flopy disu tool to create
+a simple regular grid example, but using DISU instead of DIS.
+The first case is just a simple test.  For the second case, set
+one of the cells inactive and test to make sure connectivity
+in binary grid file is correct.
+"""
+
 import os
 
 import flopy
 import numpy as np
+import pytest
 from flopy.utils.gridutil import get_disu_kwargs
 
+from framework import TestFramework
+
+cases = ["disu01a", "disu01b"]
+
 
-def test_disu_simple(tmpdir, targets):
-    mf6 = targets["mf6"]
-    name = "disu01a"
+def build_models(idx, test):
+    name = cases[idx]
+    ws = test.workspace
     nlay = 3
     nrow = 3
     ncol = 3
@@ -15,9 +28,26 @@ def test_disu_simple(tmpdir, targets):
     delc = 10.0 * np.ones(nrow)
     top = 0
     botm = [-10, -20, -30]
-    disukwargs = get_disu_kwargs(nlay, nrow, ncol, delr, delc, top, botm)
+    disukwargs = get_disu_kwargs(
+        nlay,
+        nrow,
+        ncol,
+        delr,
+        delc,
+        top,
+        botm,
+    )
+    if idx == 1:
+        # for the second test, set one cell to idomain = 0
+        idomain = np.ones((nlay, nrow * ncol), dtype=int)
+        idomain[0, 1] = 0
+        disukwargs["idomain"] = idomain
+
     sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name=mf6, sim_ws=str(tmpdir)
+        sim_name=name,
+        version="mf6",
+        exe_name="mf6",
+        sim_ws=ws,
     )
     tdis = flopy.mf6.ModflowTdis(sim)
     gwf = flopy.mf6.ModflowGwf(sim, modelname=name)
@@ -25,67 +55,36 @@ def test_disu_simple(tmpdir, targets):
     disu = flopy.mf6.ModflowGwfdisu(gwf, **disukwargs)
     ic = flopy.mf6.ModflowGwfic(gwf, strt=0.0)
     npf = flopy.mf6.ModflowGwfnpf(gwf)
-    spd = {0: [[(0,), 1.0], [(nrow * ncol - 1,), 0.0]]}
+    spd = {0: [[(0,), 1.0], [(nrow * ncol - 1), 0.0]]}
     chd = flopy.mf6.modflow.mfgwfchd.ModflowGwfchd(gwf, stress_period_data=spd)
-    sim.write_simulation()
-    sim.run_simulation()
+    return sim, None
 
 
-def test_disu_idomain_simple(tmpdir, targets):
-    mf6 = targets["mf6"]
-    name = "disu01b"
-    nlay = 3
-    nrow = 3
-    ncol = 3
-    delr = 10.0 * np.ones(ncol)
-    delc = 10.0 * np.ones(nrow)
-    top = 0
-    botm = [-10, -20, -30]
-    idomain = np.ones(nlay * nrow * ncol, dtype=int)
-    idomain[1] = 0
-    disukwargs = get_disu_kwargs(nlay, nrow, ncol, delr, delc, top, botm)
-    disukwargs["idomain"] = idomain
-    sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name=mf6, sim_ws=str(tmpdir)
-    )
-    tdis = flopy.mf6.ModflowTdis(sim)
-    gwf = flopy.mf6.ModflowGwf(sim, modelname=name, save_flows=True)
-    ims = flopy.mf6.ModflowIms(sim, print_option="SUMMARY")
-    disu = flopy.mf6.ModflowGwfdisu(gwf, **disukwargs)
-    ic = flopy.mf6.ModflowGwfic(gwf, strt=0.0)
-    npf = flopy.mf6.ModflowGwfnpf(gwf)
-    spd = {0: [[(0,), 1.0], [(nrow * ncol - 1,), 0.0]]}
-    chd = flopy.mf6.modflow.ModflowGwfchd(gwf, stress_period_data=spd)
-    oc = flopy.mf6.modflow.ModflowGwfoc(
-        gwf,
-        budget_filerecord=f"{name}.bud",
-        head_filerecord=f"{name}.hds",
-        saverecord=[("HEAD", "LAST"), ("BUDGET", "LAST")],
-    )
-    sim.write_simulation()
-    sim.run_simulation()
+def check_output(idx, test):
+    name = test.name
 
-    # check binary grid file
-    fname = os.path.join(str(tmpdir), name + ".disu.grb")
+    fname = os.path.join(test.workspace, name + ".disu.grb")
     grbobj = flopy.mf6.utils.MfGrdFile(fname)
     nodes = grbobj._datadict["NODES"]
     ia = grbobj._datadict["IA"]
     ja = grbobj._datadict["JA"]
-    assert nodes == disukwargs["nodes"]
-    assert np.array_equal(ia[0:4], np.array([1, 4, 4, 7]))
-    assert np.array_equal(ja[:6], np.array([1, 4, 10, 3, 6, 12]))
-    assert ia[-1] == 127
-    assert ia.shape[0] == 28, "ia should have size of 28"
-    assert ja.shape[0] == 126, "ja should have size of 126"
 
-    # load head array and ensure nodata value in second cell
-    fname = os.path.join(str(tmpdir), name + ".hds")
-    hdsobj = flopy.utils.HeadFile(fname)
-    head = hdsobj.get_alldata().flatten()
-    assert head[1] == 1.0e30
+    if idx == 1:
+        assert np.array_equal(ia[0:4], np.array([1, 4, 4, 7]))
+        assert np.array_equal(ja[:6], np.array([1, 4, 10, 3, 6, 12]))
+        assert ia[-1] == 127
+        assert ia.shape[0] == 28, "ia should have size of 28"
+        assert ja.shape[0] == 126, "ja should have size of 126"
 
-    # load flowja to make sure it is the right size
-    fname = os.path.join(str(tmpdir), name + ".bud")
-    budobj = flopy.utils.CellBudgetFile(fname, precision="double")
-    flowja = budobj.get_data(text="FLOW-JA-FACE")[0].flatten()
-    assert flowja.shape[0] == 126
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+    )
+    test.run()
diff --git a/autotest/test_gwf_disv.py b/autotest/test_gwf_disv.py
new file mode 100644
index 00000000000..31b08cba952
--- /dev/null
+++ b/autotest/test_gwf_disv.py
@@ -0,0 +1,96 @@
+"""
+Test of GWF DISV Package.  Use the flopy disv tool to create
+a simple regular grid example, but using DISV instead of DIS.
+Use a large offset for x and y vertices to ensure that the area
+calculation in MODFLOW 6 is correct.  For the second case, set
+one of the cells inactive and test to make sure connectivity
+in binary grid file is correct.
+"""
+
+import os
+
+import flopy
+import numpy as np
+import pytest
+from flopy.utils.gridutil import get_disv_kwargs
+
+from framework import TestFramework
+
+cases = ["disv01a", "disv01b"]
+
+
+def build_models(idx, test):
+    name = cases[idx]
+    ws = test.workspace
+    nlay = 3
+    nrow = 3
+    ncol = 3
+    delr = 10.0
+    delc = 10.0
+    top = 0
+    botm = [-10, -20, -30]
+    xoff = 100000000.0
+    yoff = 100000000.0
+    disvkwargs = get_disv_kwargs(
+        nlay,
+        nrow,
+        ncol,
+        delr,
+        delc,
+        top,
+        botm,
+        xoff,
+        yoff,
+    )
+    if idx == 1:
+        # for the second test, set one cell to idomain = 0
+        idomain = np.ones((nlay, nrow * ncol), dtype=int)
+        idomain[0, 1] = 0
+        disvkwargs["idomain"] = idomain
+
+    sim = flopy.mf6.MFSimulation(
+        sim_name=name,
+        version="mf6",
+        exe_name="mf6",
+        sim_ws=ws,
+    )
+    tdis = flopy.mf6.ModflowTdis(sim)
+    gwf = flopy.mf6.ModflowGwf(sim, modelname=name)
+    ims = flopy.mf6.ModflowIms(sim, print_option="SUMMARY")
+    disv = flopy.mf6.ModflowGwfdisv(gwf, **disvkwargs)
+    ic = flopy.mf6.ModflowGwfic(gwf, strt=0.0)
+    npf = flopy.mf6.ModflowGwfnpf(gwf)
+    spd = {0: [[(0, 0), 1.0], [(0, nrow * ncol - 1), 0.0]]}
+    chd = flopy.mf6.modflow.mfgwfchd.ModflowGwfchd(gwf, stress_period_data=spd)
+    return sim, None
+
+
+def check_output(idx, test):
+    name = test.name
+
+    fname = os.path.join(test.workspace, name + ".disv.grb")
+    grbobj = flopy.mf6.utils.MfGrdFile(fname)
+    ncpl = grbobj._datadict["NCPL"]
+    ia = grbobj._datadict["IA"]
+    ja = grbobj._datadict["JA"]
+
+    if idx == 1:
+        # assert ncpl == disvkwargs["ncpl"]
+        assert np.array_equal(ia[0:4], np.array([1, 4, 4, 7]))
+        assert np.array_equal(ja[:6], np.array([1, 4, 10, 3, 6, 12]))
+        assert ia[-1] == 127
+        assert ia.shape[0] == 28, "ia should have size of 28"
+        assert ja.shape[0] == 126, "ja should have size of 126"
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+    )
+    test.run()
diff --git a/autotest/test_gwf_disv_uzf.py b/autotest/test_gwf_disv_uzf.py
index cf89372267d..e681c041df1 100644
--- a/autotest/test_gwf_disv_uzf.py
+++ b/autotest/test_gwf_disv_uzf.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 A test of DISV with UZF.  Originally created due to a possible bug in the 
 ASCII output file generated by UZF.  Uses quadrilateral cells.  The cells 
 are created from a numpy grid with cells that are 1m x 1m.  Althought a DISV
@@ -14,97 +13,37 @@
 import flopy.utils.cvfdutil
 import numpy as np
 import pytest
+from flopy.utils.gridutil import get_disv_kwargs
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["disv_with_uzf"]
+cases = ["disv_with_uzf"]
 nlay = 5
+nrow = 10
+ncol = 10
+ncpl = nrow * ncol
+delr = 1.0
+delc = 1.0
 nper = 5
 perlen = [10] * 5
 nstp = [5] * 5
 tsmult = len(perlen) * [1.0]
+top = 25.0
 botm = [20.0, 15.0, 10.0, 5.0, 0.0]
 strt = 20
 nouter, ninner = 100, 300
 hclose, rclose, relax = 1e-9, 1e-3, 0.97
-ghb_ids = []
-
-
-def create_disv_mesh():
-    # Create a grid of verts
-    nx, ny = (11, 11)
-    x = np.linspace(0, 10, nx)
-    y = np.linspace(0, 10, ny)
-    xv, yv = np.meshgrid(x, y)
-    yv = np.flipud(yv)
-
-    verts = []
-    vid = 0
-    vert_lkup = {}
-    for i in yv[:, 0]:
-        for j in xv[0, :]:
-            vert_lkup.update({(float(j), float(i)): vid})
-            verts.append([int(vid), float(j), float(i)])
-            vid += 1
-
-    ivert = []
-    ivid = 0
-    xyverts = []
-    xc, yc = [], []  # for storing the cell center location
-    for i in yv[:-1, 0]:
-        for j in xv[0, :-1]:
-            xlst, ylst = [], []
-            vid_lst = []
-            # Start with upper-left corner and go clockwise
-            for ct in [0, 1, 2, 3]:
-                if ct == 0:
-                    iadj = 0.0
-                    jadj = 0.0
-                elif ct == 1:
-                    iadj = 0.0
-                    jadj = 1.0
-                elif ct == 2:
-                    iadj = -1.0
-                    jadj = 1.0
-                elif ct == 3:
-                    iadj = -1.0
-                    jadj = 0.0
-
-                vid = vert_lkup[(float(j + jadj), float(i + iadj))]
-                vid_lst.append(vid)
-
-                xlst.append(float(j + jadj))
-                ylst.append(float(i + iadj))
-
-            xc.append(np.mean(xlst))
-            yc.append(np.mean(ylst))
-            xyverts.append(list(zip(xlst, ylst)))
-
-            rec = [ivid] + vid_lst
-            ivert.append(rec)
-
-            # if ivert part of right boundary, store id
-            if j == 9.0:
-                ghb_ids.append(ivid)
-
-            ivid += 1
-
-    # finally, create a cell2d record
-    cell2d = []
-    for ix, iv in enumerate(ivert):
-        xvt, yvt = np.array(xyverts[ix]).T
-        if flopy.utils.geometry.is_clockwise(xvt, yvt):
-            rec = [iv[0], xc[ix], yc[ix], len(iv[1:])] + iv[1:]
-        else:
-            iiv = iv[1:][::-1]
-            rec = [iv[0], xc[ix], yc[ix], len(iiv)] + iiv
-
-        cell2d.append(rec)
-
-    return verts, cell2d
-
 
-verts, cell2d = create_disv_mesh()
+# use flopy util to get disv arguments
+disvkwargs = get_disv_kwargs(
+    nlay,
+    nrow,
+    ncol,
+    delr,
+    delc,
+    top,
+    botm,
+)
 
 # Work up UZF data
 iuzno = 0
@@ -117,7 +56,7 @@ def create_disv_mesh():
 eps = 3.5
 
 for k in np.arange(nlay):
-    for i in np.arange(0, len(cell2d), 1):
+    for i in np.arange(0, ncpl, 1):
         if k == 0:
             landflg = 1
             surfdp = 0.25
@@ -128,7 +67,7 @@ def create_disv_mesh():
         if k == nlay - 1:
             ivertcon = -1
         else:
-            ivertcon = iuzno + len(cell2d)
+            ivertcon = iuzno + ncpl
 
         bndnm = "uzf" + "{0:03d}".format(int(i + 1))
         uzf_pkdat.append(
@@ -160,7 +99,7 @@ def create_disv_mesh():
     spd = []
     iuzno = 0
     for k in np.arange(nlay):
-        for i in np.arange(0, len(cell2d), 1):
+        for i in np.arange(0, ncpl, 1):
             if k == 0:
                 if t == 0:
                     finf = 0.15
@@ -180,6 +119,7 @@ def create_disv_mesh():
 
 
 # Work up the GHB boundary
+ghb_ids = [(ncol - 1) + i * ncol for i in range(nrow)]
 ghb_spd = []
 cond = 1e4
 for k in np.arange(3, 5, 1):
@@ -187,12 +127,11 @@ def create_disv_mesh():
         ghb_spd.append([(k, i), 14.0, cond])
 
 
-def build_model(idx, dir):
-
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -230,18 +169,8 @@ def build_model(idx, dir):
     )
     sim.register_ims_package(ims, [gwf.name])
 
-    ncpl = len(cell2d)
-    nvert = len(verts)
-    disv = flopy.mf6.ModflowGwfdisv(
-        gwf,
-        nlay=nlay,
-        ncpl=ncpl,
-        nvert=nvert,
-        top=25.0,
-        botm=botm,
-        vertices=verts,
-        cell2d=cell2d,
-    )
+    # disv
+    disv = flopy.mf6.ModflowGwfdisv(gwf, **disvkwargs)
 
     # initial conditions
     ic = flopy.mf6.ModflowGwfic(gwf, strt=strt)
@@ -313,17 +242,15 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
+def check_output(idx, test):
     # Next, get the binary printed heads
-    fpth = os.path.join(sim.simpath, sim.name + ".hds")
+    fpth = os.path.join(test.workspace, test.name + ".hds")
     hobj = flopy.utils.HeadFile(fpth, precision="double")
     hds = hobj.get_alldata()
     hds = hds.reshape((np.sum(nstp), 5, 10, 10))
 
     # Get the MF6 cell-by-cell fluxes
-    bpth = os.path.join(sim.simpath, sim.name + ".cbc")
+    bpth = os.path.join(test.workspace, test.name + ".cbc")
     bobj = flopy.utils.CellBudgetFile(bpth, precision="double")
     bobj.get_unique_record_names()
     # '          STO-SS'
@@ -341,7 +268,7 @@ def eval_model(sim):
     gwet = gwetv.reshape((np.sum(nstp), 5, 10, 10))
 
     # Also retrieve the binary UZET output
-    uzpth = os.path.join(sim.simpath, sim.name + ".uzf.bud")
+    uzpth = os.path.join(test.workspace, test.name + ".uzf.bud")
     uzobj = flopy.utils.CellBudgetFile(uzpth, precision="double")
     uzobj.get_unique_record_names()
     #  b'    FLOW-JA-FACE',
@@ -389,7 +316,7 @@ def eval_model(sim):
         for rw in np.arange(arr.shape[0]):
             fullrw = arr[rw]
             for cl in np.arange(len(fullrw) - 1):
-                assert abs(fullrw[cl]) >= abs(fullrw[cl + 1]), (
+                assert abs(fullrw[cl]) + 0.01 >= abs(fullrw[cl + 1]), (
                     "gwet not decreasing to the right as expected. Stress Period: "
                     + str(tm + 1)
                     + "; Row: "
@@ -423,7 +350,7 @@ def eval_model(sim):
         for rw in np.arange(arr.shape[0]):
             fullrw = arr[rw]
             for cl in np.arange(len(fullrw) - 1):
-                assert abs(fullrw[cl]) <= abs(fullrw[cl + 1]), (
+                assert abs(fullrw[cl]) <= abs(fullrw[cl + 1]) + 0.01, (
                     "gwet not decreasing to the right as expected. Stress Period: "
                     + str(tm + 1)
                     + "; Row: "
@@ -454,13 +381,13 @@ def eval_model(sim):
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize("name", ex)
-def test_mf6model(name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, 0, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=0
-        ),
-        str(function_tmpdir),
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_drn_ddrn01.py b/autotest/test_gwf_drn_ddrn01.py
index 7814053e45c..881a2c74622 100644
--- a/autotest/test_gwf_drn_ddrn01.py
+++ b/autotest/test_gwf_drn_ddrn01.py
@@ -3,12 +3,12 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
+cases = ["drn_ddrn01a", "drn_ddrn01b"]
 paktest = "drn"
 budtol = 1e-2
-ex = ["drn_ddrn01a", "drn_ddrn01b"]
 ddir = "data"
 newton = [False, True]
 
@@ -46,10 +46,10 @@ def initial_conditions():
     return np.sqrt(h0**2 + x * (h1**2 - h0**2) / (xlen - delr))
 
 
-def get_model(idxsim, ws, name):
+def get_model(idx, ws, name):
     strt = initial_conditions()
     hdsfile = f"{name}.hds"
-    if newton[idxsim]:
+    if newton[idx]:
         newtonoptions = "NEWTON"
     else:
         newtonoptions = None
@@ -111,28 +111,26 @@ def get_model(idxsim, ws, name):
     return sim
 
 
-def build_model(idx, dir):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = get_model(idx, ws, name)
 
     return sim, None
 
 
-def eval_disch(sim):
-    print("evaluating drain discharge...")
-
+def check_output(idx, test):
     # MODFLOW 6 drain discharge results
-    fpth = os.path.join(sim.simpath, "drn_obs.csv")
+    fpth = os.path.join(test.workspace, "drn_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
         assert False, f'could not load data from "{fpth}"'
 
     # MODFLOW 6 head results
-    fpth = os.path.join(sim.simpath, "head_obs.csv")
+    fpth = os.path.join(test.workspace, "head_obs.csv")
     try:
         th0 = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -140,7 +138,7 @@ def eval_disch(sim):
 
     # calculate the drain flux analytically
     xdiff = th0["H1_1_100"] - delev
-    f = drain_smoothing(xdiff, ddrn, newton=newton[sim.idxsim])
+    f = drain_smoothing(xdiff, ddrn, newton=newton[idx])
     tc0 = f * dcond * (delev - th0["H1_1_100"])
 
     # calculate maximum absolute error
@@ -151,32 +149,29 @@ def eval_disch(sim):
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.disc.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.disc.cmp.out"
     )
-    f = open(fpth, "w")
-    line = f"{'TOTIM':>15s}"
-    line += f" {'DRN':>15s}"
-    line += f" {'UZF':>15s}"
-    line += f" {'DIFF':>15s}"
-    f.write(line + "\n")
-    for i in range(diff.shape[0]):
-        line = f"{tc['time'][i]:15g}"
-        line += f" {tc['D1_1_100'][i]:15g}"
-        line += f" {tc0[i]:15g}"
-        line += f" {diff[i]:15g}"
+    with open(fpth, "w") as f:
+        line = f"{'TOTIM':>15s}"
+        line += f" {'DRN':>15s}"
+        line += f" {'UZF':>15s}"
+        line += f" {'DIFF':>15s}"
         f.write(line + "\n")
-    f.close()
+        for i in range(diff.shape[0]):
+            line = f"{tc['time'][i]:15g}"
+            line += f" {tc['D1_1_100'][i]:15g}"
+            line += f" {tc0[i]:15g}"
+            line += f" {diff[i]:15g}"
+            f.write(line + "\n")
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
-    return
-
 
 def drain_smoothing(xdiff, xrange, newton=False):
     sat = xdiff / xrange
@@ -191,16 +186,13 @@ def drain_smoothing(xdiff, xrange, newton=False):
     return f
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_disch, idxsim=idx
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_drn_ddrn02.py b/autotest/test_gwf_drn_ddrn02.py
index 6f4cca16c45..f69068b235f 100644
--- a/autotest/test_gwf_drn_ddrn02.py
+++ b/autotest/test_gwf_drn_ddrn02.py
@@ -3,12 +3,12 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
+cases = ["drn_ddrn02a"]
 paktest = "drn"
 budtol = 1e-2
-ex = ["drn_ddrn02a"]
 
 # static model data
 # spatial discretization
@@ -108,32 +108,30 @@ def get_model(ws, name, uzf=False):
     return sim
 
 
-def build_model(idx, dir):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = get_model(ws, name)
 
     # build MODFLOW 6 files with UZF package
-    ws = os.path.join(dir, "mf6")
+    ws = os.path.join(test.workspace, "mf6")
     mc = get_model(ws, name, uzf=True)
 
     return sim, mc
 
 
-def eval_disch(sim):
-    print("evaluating drain discharge and uzf discharge to land surface...")
-
+def check_output(idx, test):
     # MODFLOW 6 drain discharge results
-    fpth = os.path.join(sim.simpath, "drn_obs.csv")
+    fpth = os.path.join(test.workspace, "drn_obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
         assert False, f'could not load data from "{fpth}"'
 
     # MODFLOW 6 uzf discharge results
-    fpth = os.path.join(sim.simpath, "mf6", "uzf_obs.csv")
+    fpth = os.path.join(test.workspace, "mf6", "uzf_obs.csv")
     try:
         tc0 = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -147,44 +145,37 @@ def eval_disch(sim):
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.disc.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.disc.cmp.out"
     )
-    f = open(fpth, "w")
-    line = f"{'TOTIM':>15s}"
-    line += f" {'DRN':>15s}"
-    line += f" {'UZF':>15s}"
-    line += f" {'DIFF':>15s}"
-    f.write(line + "\n")
-    for i in range(diff.shape[0]):
-        line = f"{tc0['time'][i]:15g}"
-        line += f" {tc['D1_1_1'][i]:15g}"
-        line += f" {tc0['D1_1_1'][i]:15g}"
-        line += f" {diff[i]:15g}"
+    with open(fpth, "w") as f:
+        line = f"{'TOTIM':>15s}"
+        line += f" {'DRN':>15s}"
+        line += f" {'UZF':>15s}"
+        line += f" {'DIFF':>15s}"
         f.write(line + "\n")
-    f.close()
+        for i in range(diff.shape[0]):
+            line = f"{tc0['time'][i]:15g}"
+            line += f" {tc['D1_1_1'][i]:15g}"
+            line += f" {tc0['D1_1_1'][i]:15g}"
+            line += f" {diff[i]:15g}"
+            f.write(line + "\n")
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=str(function_tmpdir),
-            exe_dict=targets,
-            exfunc=eval_disch,
-            idxsim=idx,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_errors.py b/autotest/test_gwf_errors.py
index c7ba06ea3b2..2d23c2fd31b 100644
--- a/autotest/test_gwf_errors.py
+++ b/autotest/test_gwf_errors.py
@@ -1,9 +1,7 @@
 """
-MODFLOW 6 Autotest
 Test to make sure that mf6 is failing with the correct error messages.  This
 test script is set up to be extensible so that simple models can be created
 very easily and tested with different options to succeed or fail correctly.
-
 """
 
 import subprocess
@@ -110,7 +108,7 @@ def get_minimal_gwf_simulation(
 
 
 def test_simple_model_success(function_tmpdir, targets):
-    mf6 = targets.mf6
+    mf6 = targets["mf6"]
 
     # test a simple model to make sure it runs and terminates correctly
     sim = get_minimal_gwf_simulation(str(function_tmpdir), mf6)
@@ -124,7 +122,7 @@ def test_simple_model_success(function_tmpdir, targets):
 
 
 def test_empty_folder(function_tmpdir, targets):
-    mf6 = targets.mf6
+    mf6 = targets["mf6"]
     with pytest.raises(RuntimeError):
         # make sure mf6 fails when there is no simulation name file
         err_str = "mf6: mfsim.nam is not present in working directory."
@@ -132,7 +130,7 @@ def test_empty_folder(function_tmpdir, targets):
 
 
 def test_sim_errors(function_tmpdir, targets):
-    mf6 = targets.mf6
+    mf6 = targets["mf6"]
 
     with pytest.raises(RuntimeError):
         # verify that the correct number of errors are reported
@@ -149,7 +147,7 @@ def test_sim_errors(function_tmpdir, targets):
 
 
 def test_sim_maxerrors(function_tmpdir, targets):
-    mf6 = targets.mf6
+    mf6 = targets["mf6"]
 
     with pytest.raises(RuntimeError):
         # verify that the maxerrors keyword gives the correct error output
@@ -176,7 +174,7 @@ def test_sim_maxerrors(function_tmpdir, targets):
 
 
 def test_disu_errors(function_tmpdir, targets):
-    mf6 = targets.mf6
+    mf6 = targets["mf6"]
 
     with pytest.raises(RuntimeError):
         disukwargs = get_disu_kwargs(
@@ -204,7 +202,7 @@ def test_disu_errors(function_tmpdir, targets):
 
 
 def test_solver_fail(function_tmpdir, targets):
-    mf6 = targets.mf6
+    mf6 = targets["mf6"]
 
     with pytest.raises(RuntimeError):
         # test failed to converge
@@ -221,7 +219,7 @@ def test_solver_fail(function_tmpdir, targets):
 
 
 def test_fail_continue_success(function_tmpdir, targets):
-    mf6 = targets.mf6
+    mf6 = targets["mf6"]
 
     # test continue but failed to converge
     tdiskwargs = {"nper": 1, "perioddata": [(10.0, 10, 1.0)]}
diff --git a/autotest/test_gwf_evt01.py b/autotest/test_gwf_evt01.py
index d90d6ccfed5..33b4ca458c2 100644
--- a/autotest/test_gwf_evt01.py
+++ b/autotest/test_gwf_evt01.py
@@ -3,14 +3,13 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["evt01"]
+from framework import TestFramework
 
+cases = ["evt01"]
 
-def build_model(idx, dir):
 
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 3
     chdheads = list(np.linspace(1, 100))
     nper = len(chdheads)
@@ -28,10 +27,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -153,14 +152,12 @@ def etfunc(h, qmax, surf, exdp, petm, pxdp, petm0=1.0):
     return q, hcof, rhs
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
-    fpth = os.path.join(sim.simpath, "evt01.cbc")
+def check_output(idx, test):
+    fpth = os.path.join(test.workspace, "evt01.cbc")
     bobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     records = bobj.get_data(text="evt")
 
-    fpth = os.path.join(sim.simpath, "evt01.hds")
+    fpth = os.path.join(test.workspace, "evt01.hds")
     hobj = flopy.utils.HeadFile(fpth, precision="double")
     heads = hobj.get_alldata()
 
@@ -177,16 +174,13 @@ def eval_model(sim):
         assert np.allclose(sim_evt_rate, cal_evt_rate), msg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=idx
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_evt02.py b/autotest/test_gwf_evt02.py
index ad1191eb7cc..a8b6adebfbb 100644
--- a/autotest/test_gwf_evt02.py
+++ b/autotest/test_gwf_evt02.py
@@ -3,14 +3,13 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["evt02"]
+from framework import TestFramework
 
+cases = ["evt02"]
 
-def build_model(idx, dir, exe):
 
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 3
     chdheads = list(np.linspace(1, 100))
     nper = len(chdheads)
@@ -28,12 +27,12 @@ def build_model(idx, dir, exe):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name=exe, sim_ws=ws
+        sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
     # create tdis package
     tdis = flopy.mf6.ModflowTdis(
@@ -151,25 +150,19 @@ def etfunc(h, qmax, surf, exdp, petm, pxdp, petm0=1.0):
     return q, hcof, rhs
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
+def check_output(idx, test):
     # The nature of the bug is that the model crashes with nseg=1
-    fpth = os.path.join(sim.simpath, "evt02.cbc")
+    fpth = os.path.join(test.workspace, "evt02.cbc")
     assert os.path.isfile(fpth), "model did not run with nseg=1 in EVT input"
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    mf6 = targets["mf6"]
-    test.build(lambda i, w: build_model(i, w, mf6), idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=idx
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_exgmvr01.py b/autotest/test_gwf_exgmvr01.py
new file mode 100644
index 00000000000..131a7c72af0
--- /dev/null
+++ b/autotest/test_gwf_exgmvr01.py
@@ -0,0 +1,309 @@
+"""
+Based on sft01 gwf model, but split into two gwf models test gwf-gwf and
+mvr. The single model is run as the regression model
+
+The final split model look like:
+
+      flow1                        flow2
+ sfr  1 2 3 4 5 6 7  gwfgwf-mvr => 1 2 3 4 5 6 7
+      -------------                -------------
+ gwf  1 2 3 4 5 6 7  gwfgwf     => 1 2 3 4 5 6 7
+"""
+
+
+import flopy
+import numpy as np
+import pytest
+
+from framework import TestFramework
+
+cases = ["gwf_exgmvr01"]
+
+# properties for single model combination
+lx = 14.0
+lz = 1.0
+nlay = 1
+nrow = 1
+ncol = 14
+nper = 1
+delc = 1.0
+delr = lx / ncol
+delz = lz / nlay
+top = 0.0
+botm = [top - (k + 1) * delz for k in range(nlay)]
+Kh = 20.0
+Kv = 20.0
+
+
+def build_simulation(idx, sim_ws, sim_type="single"):
+    name = cases[idx]
+    sim = flopy.mf6.MFSimulation(
+        sim_name=name,
+        sim_ws=sim_ws,
+    )
+
+    tdis = flopy.mf6.ModflowTdis(
+        sim,
+        time_units="DAYS",
+        nper=nper,
+    )
+
+    # Flow solver
+    ims = flopy.mf6.ModflowIms(
+        sim,
+        complexity="simple",
+        print_option="ALL",
+        outer_dvclose=1e-6,
+        inner_dvclose=1e-6,
+    )
+
+    if sim_type == "single":
+        gwf_types = ("single",)
+    else:
+        gwf_types = ("left", "right")
+    for gwf_type in gwf_types:
+        gwf = build_gwf(sim, gwf_type=gwf_type)
+
+    if sim_type != "single":
+        build_exchanges(sim)
+
+    return sim
+
+
+def build_gwf(sim, gwf_type="single"):
+    if gwf_type == "single":
+        nc = ncol
+    else:
+        nc = int(ncol / 2)
+
+    # create gwf model
+    gwf = flopy.mf6.ModflowGwf(
+        sim,
+        modelname=gwf_type,
+        save_flows=True,
+    )
+
+    dis = flopy.mf6.ModflowGwfdis(
+        gwf,
+        nlay=nlay,
+        nrow=nrow,
+        ncol=nc,
+        delr=delr,
+        delc=delc,
+        top=top,
+        botm=botm,
+    )
+
+    # initial conditions
+    ic = flopy.mf6.ModflowGwfic(gwf, strt=0.0)
+
+    # node property flow
+    npf = flopy.mf6.ModflowGwfnpf(
+        gwf,
+        save_specific_discharge=True,
+        icelltype=0,
+        k=Kh,
+        k33=Kv,
+    )
+
+    # add chd to right edge
+    if gwf_type in ("single", "right"):
+        chdlist = [
+            [(0, 0, nc - 1), 0.0],
+        ]
+        chd = flopy.mf6.ModflowGwfchd(
+            gwf,
+            stress_period_data=chdlist,
+            pname="chd_right",
+        )
+
+    # inject water into left edge
+    if gwf_type in ("single", "left"):
+        wellist = [
+            [(0, 0, 0), 1.0],
+        ]
+        wel = flopy.mf6.ModflowGwfwel(
+            gwf,
+            stress_period_data=wellist,
+            pname="well_left",
+        )
+
+    # pak_data = [<rno> <cellid(ncelldim)> <rlen> <rwid> <rgrd> <rtp> <rbth> <rhk> <man> <ncon> <ustrf> <ndv> [<aux(naux)>] [<boundname>]]
+    rlen = delr
+    rwid = delc
+    rgrd = 1.0
+    rtp = 0.0
+    rbth = 0.1
+    rhk = 0.01
+    rman = 1.0
+    ustrf = 1.0
+    ndv = 0
+    pak_data = []
+    for irno in range(nc):
+        ncon = 2
+        if irno in [0, nc - 1]:
+            ncon = 1
+        cellid = (0, 0, irno)
+        t = (
+            irno,
+            cellid,
+            rlen,
+            rwid,
+            rgrd,
+            rtp,
+            rbth,
+            rhk,
+            rman,
+            ncon,
+            ustrf,
+            ndv,
+        )
+        pak_data.append(t)
+
+    con_data = []
+    for irno in range(nc):
+        if irno == 0:
+            t = (irno, -(irno + 1))
+        elif irno == nc - 1:
+            t = (irno, irno - 1)
+        else:
+            t = (irno, irno - 1, -(irno + 1))
+        con_data.append(t)
+
+    if gwf_type in ("single", "left"):
+        p_data = [
+            (0, "INFLOW", 1.0),
+        ]
+    else:
+        p_data = None
+
+    if gwf_type != "single":
+        mover = True
+    else:
+        mover = None
+
+    sfr = flopy.mf6.modflow.ModflowGwfsfr(
+        gwf,
+        save_flows=True,
+        print_input=True,
+        print_flows=True,
+        print_stage=True,
+        mover=mover,
+        stage_filerecord=f"{gwf_type}.sfr.stg",
+        budget_filerecord=f"{gwf_type}.sfr.bud",
+        nreaches=nc,
+        packagedata=pak_data,
+        connectiondata=con_data,
+        perioddata=p_data,
+        pname=f"sfr_{gwf_type}",
+    )
+
+    # output control
+    oc = flopy.mf6.ModflowGwfoc(
+        gwf,
+        budget_filerecord=f"{gwf_type}.cbc",
+        head_filerecord=f"{gwf_type}.hds",
+        saverecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
+        printrecord=[("BUDGET", "LAST")],
+    )
+
+    return gwf
+
+
+def build_exchanges(sim):
+    # add a gwf-gwf exchange
+    gwfgwf_data = [
+        (
+            (0, 0, int(ncol / 2) - 1),
+            (0, 0, 0),
+            1,
+            delr / 2.0,
+            delr / 2.0,
+            delc,
+            0.0,
+            delr,
+        )
+    ]
+
+    # GWF-GWF
+    mvr_filerecord = "left-right.exg.mvr"
+    gwfgwf = flopy.mf6.ModflowGwfgwf(
+        sim,
+        exgtype="GWF6-GWF6",
+        nexg=len(gwfgwf_data),
+        exgmnamea="left",
+        exgmnameb="right",
+        exchangedata=gwfgwf_data,
+        auxiliary=["ANGLDEGX", "CDIST"],
+        dev_interfacemodel_on=False,
+        filename="left-right.exg",
+    )
+
+    # simulation GWF-GWF Mover
+    maxmvr, maxpackages = 1, 2
+    mvrpack_sim = [["left", "sfr_left"], ["right", "sfr_right"]]
+    mvrspd = [
+        [
+            "left",
+            "sfr_left",
+            int(ncol / 2) - 1,
+            "right",
+            "sfr_right",
+            0,
+            "FACTOR",
+            1.00,
+        ]
+    ]
+
+    gwfgwf.mvr.initialize(
+        modelnames=True,
+        maxmvr=maxmvr,
+        print_flows=True,
+        maxpackages=maxpackages,
+        packages=mvrpack_sim,
+        perioddata=mvrspd,
+        filename=mvr_filerecord,
+    )
+
+
+def build_models(idx, test):
+    sim_ws = test.workspace / "mf6"
+    sim_base = build_simulation(idx, sim_ws)
+    sim = build_simulation(idx, test.workspace, sim_type="split")
+    return sim, sim_base
+
+
+def check_output(idx, test):
+    # base simulations stage
+    ws = test.workspace
+    fpth = ws / "mf6/single.sfr.stg"
+    single_stage_obj = flopy.utils.HeadFile(fpth, text="STAGE")
+    single_stage = single_stage_obj.get_data().squeeze()
+
+    stage = single_stage.copy()
+
+    i1 = int(ncol / 2)
+    fpth = ws / "left.sfr.stg"
+    stage_obj = flopy.utils.HeadFile(fpth, text="STAGE")
+    v = stage_obj.get_data().squeeze()
+    stage[:i1] = v[:]
+
+    fpth = ws / "right.sfr.stg"
+    stage_obj = flopy.utils.HeadFile(fpth, text="STAGE")
+    v = stage_obj.get_data().squeeze()
+    stage[i1:] = v[:]
+
+    assert np.allclose(single_stage, stage), "sfr stages are not equal"
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+    )
+    test.run()
diff --git a/autotest/test_gwf_exgmvr02.py b/autotest/test_gwf_exgmvr02.py
new file mode 100644
index 00000000000..30ea52f079c
--- /dev/null
+++ b/autotest/test_gwf_exgmvr02.py
@@ -0,0 +1,355 @@
+"""
+Test the exchange mover functionality to work both ways,
+also in parallel. Use the following setup of two connected
+DIS models with a stream flow crossing the boundary twice:
+
+         
+              left:                      right:
+           .  .  .  .  .             .  .  .  .  .   1
+ sfr_in => x  x  x  x  x             x  x  x  x  x   2
+           .  .  .  .  .   gwfgwf    .  .  .  .  x   3
+sfr_out <= x  x  x  x  x             x  x  x  x  x   4
+           .  .  .  .  .             .  .  .  .  .   5
+           1  2  3  4  5             6  7  8  9  10
+
+The "single" model is also constructed as a reference.
+"""
+
+
+import flopy
+import numpy as np
+import pytest
+
+from framework import TestFramework
+
+cases = ["gwf_exgmvr02"]
+
+nper = 1
+
+lx = 10.0
+ly = 5.0
+lz = 1.0
+nlay = 1
+nrow = 5
+ncol = 10
+ncol_split = int(ncol / 2)
+nper = 1
+delc = ly / nrow
+delr = lx / ncol
+delz = lz / nlay
+top = 0.0
+botm = [top - (k + 1) * delz for k in range(nlay)]
+Kh = 20.0
+Kv = 20.0
+
+
+def make_sfr_data(sfr_cells, ireach_offset=0):
+    """generate package and connection data for a string of connected cells"""
+
+    pak_data = []
+    con_data = []
+
+    rlen = delr
+    rwid = delc
+    rgrd = 1.0
+    rtp = 0.0
+    rbth = 0.1
+    rhk = 0.01
+    rman = 1.0
+    ustrf = 1.0
+    ndv = 0
+    nc = len(sfr_cells)
+    for ridx, cellid in enumerate(sfr_cells):
+        irno = ridx + ireach_offset
+        ncon = 2
+        if ridx in [0, nc - 1]:
+            ncon = 1
+        t = (
+            irno,
+            cellid,
+            rlen,
+            rwid,
+            rgrd,
+            rtp,
+            rbth,
+            rhk,
+            rman,
+            ncon,
+            ustrf,
+            ndv,
+        )
+        pak_data.append(t)
+
+        if ridx == 0:  # first one only connected to the next
+            c = (irno, -(irno + 1))
+        elif ridx == nc - 1:  # last one only connected to the prev
+            c = (irno, irno - 1)
+        else:  # connect upstream and downstream
+            c = (irno, irno - 1, -(irno + 1))
+        con_data.append(c)
+
+    return pak_data, con_data
+
+
+def build_gwf(sim, gwf_type="single"):
+    if gwf_type == "single":
+        nc = ncol
+    else:  # left or right
+        nc = int(ncol / 2)
+
+    # create gwf model
+    gwf = flopy.mf6.ModflowGwf(
+        sim,
+        modelname=gwf_type,
+        save_flows=True,
+    )
+
+    dis = flopy.mf6.ModflowGwfdis(
+        gwf,
+        nlay=nlay,
+        nrow=nrow,
+        ncol=nc,
+        delr=delr,
+        delc=delc,
+        top=top,
+        botm=botm,
+    )
+
+    # initial conditions
+    ic = flopy.mf6.ModflowGwfic(gwf, strt=0.0)
+
+    # node property flow
+    npf = flopy.mf6.ModflowGwfnpf(
+        gwf,
+        save_specific_discharge=True,
+        icelltype=0,
+        k=Kh,
+        k33=Kv,
+    )
+
+    # add chd to right edge
+    if gwf_type in ("single", "right"):
+        chdlist = [[(0, irow, nc - 1), 0.0] for irow in range(nrow)]
+        chd = flopy.mf6.ModflowGwfchd(
+            gwf,
+            stress_period_data=chdlist,
+            pname="chd_right",
+        )
+
+    left_sfr1 = [(0, 1, icol) for icol in range(ncol_split)]
+    left_sfr2 = [(0, 3, icol - 1) for icol in range(ncol_split, 0, -1)]
+
+    right_sfr = [(0, 1, icol) for icol in range(ncol_split)]
+    right_sfr.append((0, 2, ncol_split - 1))
+    right_sfr.extend([(0, 3, icol - 1) for icol in range(ncol_split, 0, -1)])
+
+    # shift for single model:
+    for t in right_sfr:
+        print(t)
+    right_sfr_single = [(t[0], t[1], t[2] + ncol_split) for t in right_sfr]
+
+    package_data = []
+    if gwf_type == "single":
+        left_sfr1.extend(right_sfr_single)
+        left_sfr1.extend(left_sfr2)
+        package_data, conn_data = make_sfr_data(left_sfr1)
+    elif gwf_type == "left":
+        # these two are not connected
+        package_data, conn_data = make_sfr_data(left_sfr1)
+        package_data2, conn_data2 = make_sfr_data(
+            left_sfr2, ireach_offset=len(package_data)
+        )
+        package_data.extend(package_data2)
+        conn_data.extend(conn_data2)
+    elif gwf_type == "right":
+        package_data, conn_data = make_sfr_data(right_sfr)
+
+    nreaches = len(package_data)
+
+    if gwf_type in ("single", "left"):
+        period_data = [
+            (0, "INFLOW", 100.0),
+        ]
+    else:
+        period_data = None
+
+    if gwf_type != "single":
+        mover = True
+    else:
+        mover = None
+
+    sfr = flopy.mf6.modflow.ModflowGwfsfr(
+        gwf,
+        save_flows=True,
+        print_input=True,
+        print_flows=True,
+        print_stage=True,
+        mover=mover,
+        stage_filerecord=f"{gwf_type}.sfr.stg",
+        budget_filerecord=f"{gwf_type}.sfr.bud",
+        nreaches=nreaches,
+        packagedata=package_data,
+        connectiondata=conn_data,
+        perioddata=period_data,
+        pname=f"sfr_{gwf_type}",
+    )
+
+    # output control
+    oc = flopy.mf6.ModflowGwfoc(
+        gwf,
+        budget_filerecord=f"{gwf_type}.cbc",
+        head_filerecord=f"{gwf_type}.hds",
+        saverecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
+        printrecord=[("BUDGET", "LAST")],
+    )
+
+    return gwf
+
+
+def build_exchanges(sim):
+    # add a gwf-gwf exchange
+    gwfgwf_data = [
+        (
+            (0, irow, ncol_split - 1),
+            (0, irow, 0),
+            1,
+            delr / 2.0,
+            delr / 2.0,
+            delc,
+            0.0,
+            delr,
+        )
+        for irow in range(nrow)
+    ]
+
+    # GWF-GWF
+    mvr_filerecord = "left-right.exg.mvr"
+    gwfgwf = flopy.mf6.ModflowGwfgwf(
+        sim,
+        exgtype="GWF6-GWF6",
+        nexg=len(gwfgwf_data),
+        exgmnamea="left",
+        exgmnameb="right",
+        exchangedata=gwfgwf_data,
+        auxiliary=["ANGLDEGX", "CDIST"],
+        dev_interfacemodel_on=False,
+        filename="left-right.exg",
+    )
+
+    # simulation GWF-GWF Mover
+    maxmvr, maxpackages = 2, 2
+    mvrpack_sim = [["left", "sfr_left"], ["right", "sfr_right"]]
+    mvrspd = [
+        # connect left to right
+        [
+            "left",
+            "sfr_left",
+            ncol_split - 1,
+            "right",
+            "sfr_right",
+            0,
+            "FACTOR",
+            1.00,
+        ],
+        # connect right to left
+        [
+            "right",
+            "sfr_right",
+            2 * ncol_split,
+            "left",
+            "sfr_left",
+            ncol_split,
+            "FACTOR",
+            1.00,
+        ],
+    ]
+
+    gwfgwf.mvr.initialize(
+        modelnames=True,
+        maxmvr=maxmvr,
+        print_flows=True,
+        maxpackages=maxpackages,
+        packages=mvrpack_sim,
+        perioddata=mvrspd,
+        filename=mvr_filerecord,
+    )
+
+
+def build_simulation(idx, sim_ws, sim_type="single"):
+    name = cases[idx]
+    sim = flopy.mf6.MFSimulation(
+        sim_name=name,
+        sim_ws=sim_ws,
+    )
+
+    tdis = flopy.mf6.ModflowTdis(
+        sim,
+        time_units="DAYS",
+        nper=nper,
+    )
+
+    # Flow solver
+    ims = flopy.mf6.ModflowIms(
+        sim,
+        complexity="simple",
+        print_option="ALL",
+        outer_dvclose=1e-6,
+        inner_dvclose=1e-6,
+    )
+
+    if sim_type == "single":
+        gwf_types = ("single",)
+    else:
+        gwf_types = ("left", "right")
+    for gwf_type in gwf_types:
+        gwf = build_gwf(sim, gwf_type=gwf_type)
+
+    if sim_type != "single":
+        build_exchanges(sim)
+
+    return sim
+
+
+def build_models(idx, test):
+    sim_ws = test.workspace / "mf6"
+    sim_base = build_simulation(idx, sim_ws)
+    sim = build_simulation(idx, test.workspace, sim_type="split")
+    return sim, sim_base
+
+
+def check_output(idx, test):
+    # base simulations stage
+    ws = test.workspace
+    fpth = ws / "mf6/single.sfr.stg"
+    single_stage_obj = flopy.utils.HeadFile(fpth, text="STAGE")
+    single_stage = single_stage_obj.get_data().squeeze()
+
+    fpth = ws / "left.sfr.stg"
+    stage_obj = flopy.utils.HeadFile(fpth, text="STAGE")
+    v = stage_obj.get_data().squeeze()
+    assert np.allclose(
+        single_stage[0:ncol_split], v[0:ncol_split]
+    ), "sfr left (segment I) stages are not equal"
+    assert np.allclose(
+        single_stage[3 * ncol_split + 1 :], v[ncol_split:]
+    ), "sfr left (segment II) stages are not equal"
+
+    fpth = ws / "right.sfr.stg"
+    stage_obj = flopy.utils.HeadFile(fpth, text="STAGE")
+    v = stage_obj.get_data().squeeze()
+    assert np.allclose(
+        single_stage[ncol_split : 3 * ncol_split + 1], v
+    ), "sfr right stages are not equal"
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+    )
+    test.run()
diff --git a/autotest/test_gwf_henry_nr.py b/autotest/test_gwf_henry_nr.py
index c072f3f2b58..a0d3f65a0fe 100644
--- a/autotest/test_gwf_henry_nr.py
+++ b/autotest/test_gwf_henry_nr.py
@@ -1,18 +1,19 @@
-# This is the Henry, Newton-Raphson problem described by Langevin et al (2020)
-# with a 20 by 40 grid instead of the 40 by 80 grid described in the paper.
-# There is freshwater inflow on the left and a sloping sea boundary on the
-# right with moves up and down according to a simple sine function.  GHBs
-# and DRNs alternate and move up and down along the boundary to represent
-# the effects of tides on the aquifer.
+"""
+The Henry, Newton-Raphson problem described by Langevin et al (2020)
+with a 20x40 grid instead of the 40x80 grid described in the paper.
+There is freshwater inflow on the left. A sloping sea boundary on the
+right moves up and down according to a simple sine function. GHBs and
+DRNs alternate and move up and down along the boundary to represent
+the effects of tides on the aquifer.
+"""
 
 import flopy
 import numpy as np
 import pytest
-from conftest import should_compare
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["gwf_henrynr01"]
+cases = ["gwf_henrynr01"]
 
 # global model variables
 nlay = 20
@@ -65,9 +66,9 @@ def sinfunc(a, b, c, d, x):
     return a * np.sin(b * (x - c)) + d
 
 
-def build_model(idx, dir, exe):
-    ws = dir
-    name = ex[idx]
+def build_models(idx, test):
+    ws = test.workspace
+    name = cases[idx]
 
     nrow = 1
     delr = lx / ncol
@@ -89,7 +90,7 @@ def build_model(idx, dir, exe):
 
     # build MODFLOW 6 files
     sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name=exe, sim_ws=ws
+        sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
     sim.name_file.continue_ = False
 
@@ -231,26 +232,16 @@ def build_model(idx, dir, exe):
     return sim, None
 
 
-# - No need to change any code below
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
     name = "gwf-henry-nr"
-    comparisons = {name: ("6.2.1",)}
-    mf6 = targets["mf6"]
-    test = TestFramework()
-    test.build(lambda i, w: build_model(i, w, mf6), idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            idxsim=idx,
-            mf6_regression=True,
-            cmp_verbose=False,
-            make_comparison=should_compare(name, comparisons, targets),
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        compare="mf6_regression",
+        verbose=False,
     )
+    test.run()
diff --git a/autotest/test_gwf_ifmod_buy.py b/autotest/test_gwf_ifmod_buy.py
index 428b025c230..0f0bfa5df4d 100644
--- a/autotest/test_gwf_ifmod_buy.py
+++ b/autotest/test_gwf_ifmod_buy.py
@@ -1,34 +1,36 @@
+"""
+General test for the interface model approach.
+It compares the result of a single reference model
+to the equivalent case where the domain is decomposed
+and joined by a GWF-GWF exchange.
+
+       'refmodel'              'leftmodel'     'rightmodel'
+
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1    VS    1 1 1 1 1   +   1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+
+We assert equality on the head values and the (components of)
+specific discharges. All models are part of the same solution
+for convenience. Finally, the budget error is checked.
+"""
+
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
-
-# General test for the interface model approach.
-# It compares the result of a single reference model
-# to the equivalent case where the domain is decomposed
-# and joined by a GWF-GWF exchange.
-#
-#        'refmodel'              'leftmodel'     'rightmodel'
-#
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1    VS    1 1 1 1 1   +   1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#
-# We assert equality on the head values and the (components of)
-# specific discharges. All models are part of the same solution
-# for convenience. Finally, the budget error is checked.
-
-ex = ["ifmod_buy01"]
+
+cases = ["ifmod_buy01"]
 
 # some global convenience...:
 # model names
@@ -84,7 +86,7 @@
 
 
 def get_model(idx, dir):
-    name = ex[idx]
+    name = cases[idx]
 
     # parameters and spd
     # tdis
@@ -179,7 +181,6 @@ def get_model(idx, dir):
 
 
 def add_refmodel(sim):
-
     gwf = flopy.mf6.ModflowGwf(sim, modelname=mname_ref, save_flows=True)
 
     dis = flopy.mf6.ModflowGwfdis(
@@ -231,7 +232,6 @@ def add_refmodel(sim):
 
 
 def add_leftmodel(sim):
-
     left_chd = [[(0, irow, 0), h_left] for irow in range(nrow)]
     chd_spd_left = {0: left_chd}
 
@@ -273,7 +273,6 @@ def add_leftmodel(sim):
 
 
 def add_rightmodel(sim):
-
     right_chd = [[(0, irow, ncol_right - 1), h_right] for irow in range(nrow)]
     chd_spd_right = {0: right_chd}
 
@@ -317,7 +316,6 @@ def add_rightmodel(sim):
 
 
 def add_gwfexchange(sim):
-
     angldegx = 0.0
     cdist = delr
     gwfgwf_data = [
@@ -346,7 +344,6 @@ def add_gwfexchange(sim):
 
 
 def add_gwtrefmodel(sim):
-
     gwt = flopy.mf6.ModflowGwt(sim, modelname=mname_gwtref)
 
     dis = flopy.mf6.ModflowGwtdis(
@@ -393,7 +390,6 @@ def add_gwtrefmodel(sim):
 
 
 def add_gwtleftmodel(sim):
-
     gwt = flopy.mf6.ModflowGwt(sim, modelname=mname_gwtleft)
 
     dis = flopy.mf6.ModflowGwtdis(
@@ -440,7 +436,6 @@ def add_gwtleftmodel(sim):
 
 
 def add_gwtrightmodel(sim):
-
     gwt = flopy.mf6.ModflowGwt(sim, modelname=mname_gwtright)
 
     dis = flopy.mf6.ModflowGwtdis(
@@ -489,7 +484,6 @@ def add_gwtrightmodel(sim):
 
 
 def add_gwtexchange(sim):
-
     angldegx = 0.0
     cdist = delr
     gwtgwt_data = [
@@ -518,8 +512,8 @@ def add_gwtexchange(sim):
     )
 
 
-def build_model(idx, exdir):
-    sim = get_model(idx, exdir)
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace)
     return sim, None
 
 
@@ -543,27 +537,27 @@ def qxqyqz(fname, nlay, nrow, ncol):
     return qx, qy, qz
 
 
-def compare_to_ref(sim):
+def check_output(idx, test):
     print("comparing heads and spec. discharge to single model reference...")
 
-    fpth = os.path.join(sim.simpath, f"{mname_ref}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_ref}.hds")
     hds = flopy.utils.HeadFile(fpth)
     heads = hds.get_data()
-    fpth = os.path.join(sim.simpath, f"{mname_ref}.cbc")
+    fpth = os.path.join(test.workspace, f"{mname_ref}.cbc")
     nlay, nrow, ncol = heads.shape
     qxb, qyb, qzb = qxqyqz(fpth, nlay, nrow, ncol)
 
-    fpth = os.path.join(sim.simpath, f"{mname_left}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_left}.hds")
     hds = flopy.utils.HeadFile(fpth)
     heads_left = hds.get_data()
-    fpth = os.path.join(sim.simpath, f"{mname_left}.cbc")
+    fpth = os.path.join(test.workspace, f"{mname_left}.cbc")
     nlay, nrow, ncol = heads_left.shape
     qxb_left, qyb_left, qzb_left = qxqyqz(fpth, nlay, nrow, ncol)
 
-    fpth = os.path.join(sim.simpath, f"{mname_right}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_right}.hds")
     hds = flopy.utils.HeadFile(fpth)
     heads_right = hds.get_data()
-    fpth = os.path.join(sim.simpath, f"{mname_right}.cbc")
+    fpth = os.path.join(test.workspace, f"{mname_right}.cbc")
     nlay, nrow, ncol = heads_right.shape
     qxb_right, qyb_right, qzb_right = qxqyqz(fpth, nlay, nrow, ncol)
 
@@ -634,7 +628,7 @@ def compare_to_ref(sim):
 
     # check budget error from .lst file
     for mname in [mname_ref, mname_left, mname_right]:
-        fpth = os.path.join(sim.simpath, f"{mname}.lst")
+        fpth = os.path.join(test.workspace, f"{mname}.lst")
         for line in open(fpth):
             if line.lstrip().startswith("PERCENT"):
                 cumul_balance_error = float(line.split()[3])
@@ -645,17 +639,14 @@ def compare_to_ref(sim):
                 )
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 @pytest.mark.developmode
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=compare_to_ref, idxsim=idx
-        ),
-        str(function_tmpdir),
-    )
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+    )
+    test.run()
diff --git a/autotest/test_gwf_ifmod_idomain.py b/autotest/test_gwf_ifmod_idomain.py
index 4f89039dd14..8f5ac4c18d0 100644
--- a/autotest/test_gwf_ifmod_idomain.py
+++ b/autotest/test_gwf_ifmod_idomain.py
@@ -1,28 +1,30 @@
+"""
+General test for the interface model approach.
+It compares the result of a single reference model
+to the equivalent case where the domain is decomposed
+and joined by a GWF-GWF exchange.
+
+In this case we test the use of idomain at the interface
+
+                  'refmodel'                 'leftmodel'     'rightmodel'
+
+   layer 1:  1 1 1 1 0 0 1 1 1 1            1 1 1 1 0       0 1 1 1 1
+   layer 2:  1 1 1 1 1 1 1 1 1 1     VS     1 1 1 1 1   +   1 1 1 1 1
+   layer 3:  1 1 1 1 1 1 1 1 1 1            1 1 1 1 1       1 1 1 1 1
+
+We assert equality on the head values. All models are part of a single
+solution for convenience. Finally, the budget error is checked.
+"""
+
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
-
-# General test for the interface model approach.
-# It compares the result of a single reference model
-# to the equivalent case where the domain is decomposed
-# and joined by a GWF-GWF exchange.
-#
-# In this case we test the use of idomain at the interface
-#
-#                   'refmodel'                 'leftmodel'     'rightmodel'
-#
-#    layer 1:  1 1 1 1 0 0 1 1 1 1            1 1 1 1 0       0 1 1 1 1
-#    layer 2:  1 1 1 1 1 1 1 1 1 1     VS     1 1 1 1 1   +   1 1 1 1 1
-#    layer 3:  1 1 1 1 1 1 1 1 1 1            1 1 1 1 1       1 1 1 1 1
-#
-# We assert equality on the head values. All models are part of a single
-# solution for convenience. Finally, the budget error is checked.
-
-ex = ["ifmod_ibound"]
+
+cases = ["ifmod_ibound"]
 
 # some global convenience...:
 # model names
@@ -73,7 +75,7 @@
 h_right = 75.0
 
 # initial head
-h_start = 0.0 
+h_start = 0.0
 
 
 # head boundaries
@@ -103,7 +105,7 @@
 
 
 def get_model(idx, dir):
-    name = ex[idx]
+    name = cases[idx]
 
     # parameters and spd
     # tdis
@@ -272,11 +274,7 @@ def add_rightmodel(sim):
     )
     ic = flopy.mf6.ModflowGwfic(gwf, strt=h_start)
     npf = flopy.mf6.ModflowGwfnpf(
-        gwf,
-        save_specific_discharge=True,
-        save_flows=True,
-        icelltype=0,   
-        k=hk
+        gwf, save_specific_discharge=True, save_flows=True, icelltype=0, k=hk
     )
     chd = flopy.mf6.ModflowGwfchd(gwf, stress_period_data=chd_spd_right)
     oc = flopy.mf6.ModflowGwfoc(
@@ -312,8 +310,8 @@ def add_gwfexchange(sim):
         ]
         for ilay in range(nlay)
         for irow in range(nrow)
-        if idomain_left[ilay, irow, ncol_left - 1] > 0 and 
-           idomain_right[ilay, irow, 0] > 0
+        if idomain_left[ilay, irow, ncol_left - 1] > 0
+        and idomain_right[ilay, irow, 0] > 0
     ]
     gwfgwf = flopy.mf6.ModflowGwfgwf(
         sim,
@@ -327,31 +325,31 @@ def add_gwfexchange(sim):
     )
 
 
-def build_model(idx, exdir):
-    sim = get_model(idx, exdir)
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace)
     return sim, None
 
 
-def compare_to_ref(sim):
+def check_output(idx, test):
     print("comparing heads to single model reference...")
 
-    fpth = os.path.join(sim.simpath, f"{mname_ref}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_ref}.hds")
     hds = flopy.utils.HeadFile(fpth)
-    fpth = os.path.join(sim.simpath, f"{mname_left}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_left}.hds")
     hds_l = flopy.utils.HeadFile(fpth)
-    fpth = os.path.join(sim.simpath, f"{mname_right}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_right}.hds")
     hds_r = flopy.utils.HeadFile(fpth)
 
     times = hds.get_times()
     for t in times:
         heads = hds.get_data(totim=t)
-        heads_left = hds_l.get_data(totim=t)        
+        heads_left = hds_l.get_data(totim=t)
         heads_right = hds_r.get_data(totim=t)
         heads_2models = np.append(heads_left, heads_right, axis=2)
 
         # check idomain was used
-        assert heads[0, 0, 4] == 1.0e+30, "idomain was set to 0 for this cell"
-        assert heads[0, 0, 5] == 1.0e+30, "idomain was set to 0 for this cell"
+        assert heads[0, 0, 4] == 1.0e30, "idomain was set to 0 for this cell"
+        assert heads[0, 0, 5] == 1.0e30, "idomain was set to 0 for this cell"
 
         # compare heads
         maxdiff = np.amax(abs(heads - heads_2models))
@@ -364,7 +362,7 @@ def compare_to_ref(sim):
 
     # check budget error from .lst file
     for mname in [mname_ref, mname_left, mname_right]:
-        fpth = os.path.join(sim.simpath, f"{mname}.lst")
+        fpth = os.path.join(test.workspace, f"{mname}.lst")
         for line in open(fpth):
             if line.lstrip().startswith("PERCENT"):
                 cumul_balance_error = float(line.split()[3])
@@ -375,17 +373,14 @@ def compare_to_ref(sim):
                 )
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 @pytest.mark.developmode
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=compare_to_ref, idxsim=idx
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_ifmod_mult_exg.py b/autotest/test_gwf_ifmod_mult_exg.py
index dc179b804db..c5593f0b75e 100644
--- a/autotest/test_gwf_ifmod_mult_exg.py
+++ b/autotest/test_gwf_ifmod_mult_exg.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 Test the interface model approach for multiple (2) exchanges between
 the same two models. One exchange has XT3D and the other one doesn't.
 
@@ -19,18 +18,18 @@
 will have the XT3D calculation enabled.
 
 TODO: (how) will this affect accuracy?
-
 """
+
 import os
 
 import flopy
 import numpy as np
 import pytest
 from flopy.utils.lgrutil import Lgr
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["ifmod_mult_exg"]
+cases = ["ifmod_mult_exg"]
 name_parent = "parent"
 name_child = "child"
 g_delr = 10.0
@@ -41,7 +40,7 @@
 
 
 def get_model(idx, dir):
-    name = ex[idx]
+    name = cases[idx]
 
     # parameters and spd
     # tdis
@@ -256,25 +255,25 @@ def get_model(idx, dir):
     return sim
 
 
-def build_model(idx, exdir):
-    sim = get_model(idx, exdir)
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace)
     return sim, None
 
 
-def eval_heads(sim):
-    fpth = os.path.join(sim.simpath, f"{name_parent}.hds")
+def check_output(idx, test):
+    fpth = os.path.join(test.workspace, f"{name_parent}.hds")
     hds = flopy.utils.HeadFile(fpth)
     heads = hds.get_data()
 
-    fpth = os.path.join(sim.simpath, f"{name_child}.hds")
+    fpth = os.path.join(test.workspace, f"{name_child}.hds")
     hds_c = flopy.utils.HeadFile(fpth)
     heads_c = hds_c.get_data()
 
-    fpth = os.path.join(sim.simpath, f"{name_parent}.dis.grb")
+    fpth = os.path.join(test.workspace, f"{name_parent}.dis.grb")
     grb = flopy.mf6.utils.MfGrdFile(fpth)
     mg = grb.modelgrid
 
-    fpth = os.path.join(sim.simpath, f"{name_child}.dis.grb")
+    fpth = os.path.join(test.workspace, f"{name_child}.dis.grb")
     grb_c = flopy.mf6.utils.MfGrdFile(fpth)
     mg_c = grb_c.modelgrid
 
@@ -330,17 +329,14 @@ def exact(x):
     # assert maxdiff_child_south > maxdiff_child_north
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 @pytest.mark.developmode
-def test_mf6model(name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, 0, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_heads, idxsim=0
-        ),
-        str(function_tmpdir),
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_ifmod_newton.py b/autotest/test_gwf_ifmod_newton.py
index abfc8e2a3c8..9ae844132e5 100644
--- a/autotest/test_gwf_ifmod_newton.py
+++ b/autotest/test_gwf_ifmod_newton.py
@@ -1,34 +1,36 @@
+"""
+General test for the interface model approach.
+It compares the result of a single reference model
+to the equivalent case where the domain is decomposed
+and joined by a GWF-GWF exchange.
+
+In this case we test newton option, which is also enabled in
+the interface model and should give identical results.
+
+period 1: The first stress period we start almost dry and have the
+          model fill up.
+period 2: The BC on the left is lowered such that a part of the top
+          layer is drained.
+
+                 'refmodel'               'leftmodel'    'rightmodel'
+
+   layer 1:  1 . . . . . . . 1            1 . . . . 1       1 . . 1
+   layer 2:  1 . . . . . . . 1     VS     1 . . . . 1   +   1 . . 1
+   layer 3:  1 . . . . . . . 1            1 . . . . 1       1 . . 1
+
+We assert equality on the head values. All models are part of the same
+solution for convenience. Finally, the budget error is checked.
+"""
+
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
-
-# General test for the interface model approach.
-# It compares the result of a single reference model
-# to the equivalent case where the domain is decomposed
-# and joined by a GWF-GWF exchange.
-#
-# In this case we test newton option, which is also enabled in
-# the interface model and should give identical results.
-#
-# period 1: The first stress period we start almost dry and have the
-#           model fill up.
-# period 2: The BC on the left is lowered such that a part of the top
-#           layer is drained.
-#
-#                  'refmodel'               'leftmodel'    'rightmodel'
-#
-#    layer 1:  1 . . . . . . . 1            1 . . . . 1       1 . . 1
-#    layer 2:  1 . . . . . . . 1     VS     1 . . . . 1   +   1 . . 1
-#    layer 3:  1 . . . . . . . 1            1 . . . . 1       1 . . 1
-#
-# We assert equality on the head values. All models are part of the same
-# solution for convenience. Finally, the budget error is checked.
-
-ex = ["ifmod_newton01"]
+
+cases = ["ifmod_newton01"]
 
 # some global convenience...:
 # model names
@@ -109,8 +111,8 @@
 chd_spd_right[1] = rchd_right
 
 
-def get_model(idx, dir):
-    name = ex[idx]
+def get_model(idx, ws):
+    name = cases[idx]
 
     # parameters and spd
     # tdis
@@ -123,7 +125,7 @@ def get_model(idx, dir):
     hclose, rclose, relax = hclose_check, 1e-3, 0.97
 
     sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name="mf6", sim_ws=dir
+        sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
 
     tdis = flopy.mf6.ModflowTdis(
@@ -175,8 +177,9 @@ def add_refmodel(sim):
     global chd_spd
     global tops
 
-    gwf = flopy.mf6.ModflowGwf(sim, modelname=mname_ref, newtonoptions="NEWTON", 
-                               save_flows=True)
+    gwf = flopy.mf6.ModflowGwf(
+        sim, modelname=mname_ref, newtonoptions="NEWTON", save_flows=True
+    )
 
     dis = flopy.mf6.ModflowGwfdis(
         gwf,
@@ -226,8 +229,9 @@ def add_leftmodel(sim):
     global h_left
     global chd_spd_left
 
-    gwf = flopy.mf6.ModflowGwf(sim, modelname=mname_left, newtonoptions="NEWTON",
-                               save_flows=True)
+    gwf = flopy.mf6.ModflowGwf(
+        sim, modelname=mname_left, newtonoptions="NEWTON", save_flows=True
+    )
     dis = flopy.mf6.ModflowGwfdis(
         gwf,
         nlay=nlay,
@@ -268,8 +272,9 @@ def add_rightmodel(sim):
     global shift_x, shift_y
     global chd_spd_right
 
-    gwf = flopy.mf6.ModflowGwf(sim, modelname=mname_right, newtonoptions="NEWTON",
-                               save_flows=True)
+    gwf = flopy.mf6.ModflowGwf(
+        sim, modelname=mname_right, newtonoptions="NEWTON", save_flows=True
+    )
     dis = flopy.mf6.ModflowGwfdis(
         gwf,
         nlay=nlay,
@@ -336,19 +341,19 @@ def add_gwfexchange(sim):
     )
 
 
-def build_model(idx, exdir):
-    sim = get_model(idx, exdir)
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace)
     return sim, None
 
 
-def compare_to_ref(sim):
+def check_output(idx, test):
     print("comparing heads to single model reference...")
 
-    fpth = os.path.join(sim.simpath, f"{mname_ref}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_ref}.hds")
     hds = flopy.utils.HeadFile(fpth)
-    fpth = os.path.join(sim.simpath, f"{mname_left}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_left}.hds")
     hds_l = flopy.utils.HeadFile(fpth)
-    fpth = os.path.join(sim.simpath, f"{mname_right}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_right}.hds")
     hds_r = flopy.utils.HeadFile(fpth)
 
     times = hds.get_times()
@@ -369,7 +374,7 @@ def compare_to_ref(sim):
 
     # check budget error from .lst file
     for mname in [mname_ref, mname_left, mname_right]:
-        fpth = os.path.join(sim.simpath, f"{mname}.lst")
+        fpth = os.path.join(test.workspace, f"{mname}.lst")
         for line in open(fpth):
             if line.lstrip().startswith("PERCENT"):
                 cumul_balance_error = float(line.split()[3])
@@ -380,17 +385,14 @@ def compare_to_ref(sim):
                 )
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 @pytest.mark.developmode
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=compare_to_ref, idxsim=idx
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_ifmod_rewet.py b/autotest/test_gwf_ifmod_rewet.py
index feb98489108..42562768c17 100644
--- a/autotest/test_gwf_ifmod_rewet.py
+++ b/autotest/test_gwf_ifmod_rewet.py
@@ -1,36 +1,38 @@
+"""
+General test for the interface model approach.
+It compares the result of a single reference model
+to the equivalent case where the domain is decomposed
+and joined by a GWF-GWF exchange.
+
+In this case we test rewetting, which is also enabled in
+the interface model and should give identical results.
+
+period 1: The first stress period we start almost dry and have the
+          model fill up.
+period 2: The BC on the left is lowered such that a part of the top
+          layer dries. To test the interface, the value is chosen such
+          that the boundary cell on the left is DRY and the one on the
+          right isn't.
+
+                 'refmodel'               'leftmodel'    'rightmodel'
+
+   layer 1:  1 . . . . . . . 1            1 . . . . 1       1 . . 1
+   layer 2:  1 . . . . . . . 1     VS     1 . . . . 1   +   1 . . 1
+   layer 3:  1 . . . . . . . 1            1 . . . . 1       1 . . 1
+
+We assert equality on the head values. All models are part of the same
+solution for convenience. Finally, the budget error is checked.
+"""
+
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
-
-# General test for the interface model approach.
-# It compares the result of a single reference model
-# to the equivalent case where the domain is decomposed
-# and joined by a GWF-GWF exchange.
-#
-# In this case we test rewetting, which is also enabled in
-# the interface model and should give identical results.
-#
-# period 1: The first stress period we start almost dry and have the
-#           model fill up.
-# period 2: The BC on the left is lowered such that a part of the top
-#           layer dries. To test the interface, the value is chosen such 
-#           that the boundary cell on the left is DRY and the one on the 
-#           right isn't.
-#
-#                  'refmodel'               'leftmodel'    'rightmodel'
-#
-#    layer 1:  1 . . . . . . . 1            1 . . . . 1       1 . . 1
-#    layer 2:  1 . . . . . . . 1     VS     1 . . . . 1   +   1 . . 1
-#    layer 3:  1 . . . . . . . 1            1 . . . . 1       1 . . 1
-#
-# We assert equality on the head values. All models are part of the same
-# solution for convenience. Finally, the budget error is checked.
-
-ex = ["ifmod_rewet01"]
+
+cases = ["ifmod_rewet01"]
 
 # some global convenience...:
 # model names
@@ -116,7 +118,7 @@
 
 
 def get_model(idx, dir):
-    name = ex[idx]
+    name = cases[idx]
 
     # parameters and spd
     # tdis
@@ -348,25 +350,25 @@ def add_gwfexchange(sim):
     )
 
 
-def build_model(idx, exdir):
-    sim = get_model(idx, exdir)
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace)
     return sim, None
 
 
-def compare_to_ref(sim):
+def check_output(idx, test):
     print("comparing heads to single model reference...")
 
-    fpth = os.path.join(sim.simpath, f"{mname_ref}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_ref}.hds")
     hds = flopy.utils.HeadFile(fpth)
-    fpth = os.path.join(sim.simpath, f"{mname_left}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_left}.hds")
     hds_l = flopy.utils.HeadFile(fpth)
-    fpth = os.path.join(sim.simpath, f"{mname_right}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_right}.hds")
     hds_r = flopy.utils.HeadFile(fpth)
 
     times = hds.get_times()
-    for iper, t in enumerate(times):        
+    for iper, t in enumerate(times):
         heads = hds.get_data(totim=t)
-        heads_left = hds_l.get_data(totim=t)        
+        heads_left = hds_l.get_data(totim=t)
         heads_right = hds_r.get_data(totim=t)
         heads_2models = np.append(heads_left, heads_right, axis=2)
 
@@ -374,9 +376,13 @@ def compare_to_ref(sim):
         # dry in period 2, but the cells in the right model should remain
         # active. This tests the interface model for dealing with drying
         # and wetting, and handling inactive cells, explicitly
-        if (iper == 1):
-            assert np.all(heads_left[0,0,:] == -1.0e+30), "left model, top layer should be DRY in period 2"
-            assert np.all(heads_right[0,0,:] > -1.0e+30), "right model, top layer should be WET in period 2"
+        if iper == 1:
+            assert np.all(
+                heads_left[0, 0, :] == -1.0e30
+            ), "left model, top layer should be DRY in period 2"
+            assert np.all(
+                heads_right[0, 0, :] > -1.0e30
+            ), "right model, top layer should be WET in period 2"
 
         # compare heads
         maxdiff = np.amax(abs(heads - heads_2models))
@@ -389,7 +395,7 @@ def compare_to_ref(sim):
 
     # check budget error from .lst file
     for mname in [mname_ref, mname_left, mname_right]:
-        fpth = os.path.join(sim.simpath, f"{mname}.lst")
+        fpth = os.path.join(test.workspace, f"{mname}.lst")
         for line in open(fpth):
             if line.lstrip().startswith("PERCENT"):
                 cumul_balance_error = float(line.split()[3])
@@ -400,17 +406,14 @@ def compare_to_ref(sim):
                 )
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 @pytest.mark.developmode
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=compare_to_ref, idxsim=idx
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_ifmod_vert.py b/autotest/test_gwf_ifmod_vert.py
index 5e5240726a7..cf480fa2f9a 100644
--- a/autotest/test_gwf_ifmod_vert.py
+++ b/autotest/test_gwf_ifmod_vert.py
@@ -28,18 +28,18 @@
 the child model should match the theory. In this case we
 just assert that they are equal for each column, something
 that is clearly not true when simulating without XT3D.
-
 """
+
 import os
 
 import flopy
 import numpy as np
 import pytest
 from flopy.utils.lgrutil import Lgr
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["ifmod_vert"]
+cases = ["ifmod_vert"]
 
 parent_name = "parent"
 child_name = "child"
@@ -55,7 +55,7 @@ def get_model(idx, dir):
     global child_domain
     global hclose
 
-    name = ex[idx]
+    name = cases[idx]
 
     # tdis period data
     nper = 1
@@ -234,19 +234,19 @@ def get_model(idx, dir):
     return sim
 
 
-def build_model(idx, exdir):
-    sim = get_model(idx, exdir)
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace)
     return sim, None
 
 
-def eval_heads(sim):
+def check_output(idx, test):
     print("comparing heads  for child model to analytical result...")
 
-    fpth = os.path.join(sim.simpath, f"{child_name}.hds")
+    fpth = os.path.join(test.workspace, f"{child_name}.hds")
     hds_c = flopy.utils.HeadFile(fpth)
     heads_c = hds_c.get_data()
 
-    fpth = os.path.join(sim.simpath, f"{child_name}.dis.grb")
+    fpth = os.path.join(test.workspace, f"{child_name}.dis.grb")
     grb_c = flopy.mf6.utils.MfGrdFile(fpth)
 
     # (note that without XT3D on the exchange, the 'error'
@@ -262,11 +262,11 @@ def eval_heads(sim):
     for mname in [parent_name, child_name]:
         print(f"Checking flowja residual for model {mname}")
 
-        fpth = os.path.join(sim.simpath, f"{mname}.dis.grb")
+        fpth = os.path.join(test.workspace, f"{mname}.dis.grb")
         grb = flopy.mf6.utils.MfGrdFile(fpth)
         ia = grb._datadict["IA"] - 1
 
-        fpth = os.path.join(sim.simpath, f"{mname}.cbc")
+        fpth = os.path.join(test.workspace, f"{mname}.cbc")
         assert os.path.isfile(fpth)
         cbb = flopy.utils.CellBudgetFile(fpth, precision="double")
         flow_ja_face = cbb.get_data(idx=0)
@@ -281,17 +281,14 @@ def eval_heads(sim):
             assert np.allclose(res, 0.0, atol=1.0e-6), errmsg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 @pytest.mark.developmode
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_heads, idxsim=idx
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_ifmod_xt3d01.py b/autotest/test_gwf_ifmod_xt3d01.py
index bcff3b72dc8..2da24e89601 100644
--- a/autotest/test_gwf_ifmod_xt3d01.py
+++ b/autotest/test_gwf_ifmod_xt3d01.py
@@ -1,37 +1,39 @@
+"""
+Test the interface model approach, when running
+with a GWF-GWF exchange and XT3D applied on it.
+It compares the result for a simple LGR configuration
+to the analytical values:
+
+        1 1 1 1 1 1 1
+        1 1 1 1 1 1 1
+        1 1 0 0 0 1 1
+(H=1.0) 1 1 0 0 0 1 1 (H=0.0)
+        1 1 0 0 0 1 1
+        1 1 1 1 1 1 1
+        1 1 1 1 1 1 1
+
+with the region with ibound == 0 being simulated on the
+a refined, 9x9 grid.
+
+This is also the first test problem presented in
+the MODFLOW-USG manual: 'test006_2models'
+
+When running without XT3D, the results will disagree
+with theory because the CVFD requirements are violated at the
+at the LGR interface. We compare heads, specific discharge, and
+confirm that there is no budget error.
+"""
+
 import os
 
 import flopy
 import numpy as np
 import pytest
 from flopy.utils.lgrutil import Lgr
+
 from framework import TestFramework
-from simulation import TestSimulation
-
-# Test for the interface model approach, when running
-# with a GWF-GWF exchange and XT3D applied on it.
-# It compares the result for a simple LGR configuration
-# to the analytical values:
-#
-#         1 1 1 1 1 1 1
-#         1 1 1 1 1 1 1
-#         1 1 0 0 0 1 1
-# (H=1.0) 1 1 0 0 0 1 1 (H=0.0)
-#         1 1 0 0 0 1 1
-#         1 1 1 1 1 1 1
-#         1 1 1 1 1 1 1
-#
-# with the region with ibound == 0 being simulated on the
-# a refined, 9x9 grid.
-#
-# This is also the first test problem presented in
-# the MODFLOW-USG manual: 'test006_2models'
-#
-# When running without XT3D, the results will disagree
-# with theory because the CVFD requirements are violated at the
-# at the LGR interface. We compare heads, specific discharge, and
-# confirm that there is no budget error.
-
-ex = ["ifmod_xt3d01"]
+
+cases = ["ifmod_xt3d01"]
 
 # globally for convenience...
 useXT3D = True
@@ -51,7 +53,7 @@ def get_model(idx, dir):
     global child_domain
     global hclose
 
-    name = ex[idx]
+    name = cases[idx]
 
     # tdis period data
     nper = 1
@@ -274,8 +276,8 @@ def get_model(idx, dir):
     return sim
 
 
-def build_model(idx, exdir):
-    sim = get_model(idx, exdir)
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace)
     return sim, None
 
 
@@ -299,30 +301,30 @@ def qxqyqz(fname, nlay, nrow, ncol):
     return qx, qy, qz
 
 
-def eval_heads(sim):
+def check_output(idx, test):
     print("comparing heads and spec. discharges to analytical result...")
 
-    fpth = os.path.join(sim.simpath, f"{parent_name}.hds")
+    fpth = os.path.join(test.workspace, f"{parent_name}.hds")
     hds = flopy.utils.HeadFile(fpth)
     heads = hds.get_data()
 
-    fpth = os.path.join(sim.simpath, f"{parent_name}.cbc")
+    fpth = os.path.join(test.workspace, f"{parent_name}.cbc")
     nlay, nrow, ncol = heads.shape
     qxb, qyb, qzb = qxqyqz(fpth, nlay, nrow, ncol)
 
-    fpth = os.path.join(sim.simpath, f"{child_name}.hds")
+    fpth = os.path.join(test.workspace, f"{child_name}.hds")
     hds_c = flopy.utils.HeadFile(fpth)
     heads_c = hds_c.get_data()
 
-    fpth = os.path.join(sim.simpath, f"{child_name}.cbc")
+    fpth = os.path.join(test.workspace, f"{child_name}.cbc")
     nlay, nrow, ncol = heads_c.shape
     qxb_c, qyb_c, qzb_c = qxqyqz(fpth, nlay, nrow, ncol)
 
-    fpth = os.path.join(sim.simpath, f"{parent_name}.dis.grb")
+    fpth = os.path.join(test.workspace, f"{parent_name}.dis.grb")
     grb = flopy.mf6.utils.MfGrdFile(fpth)
     mg = grb.modelgrid
 
-    fpth = os.path.join(sim.simpath, f"{child_name}.dis.grb")
+    fpth = os.path.join(test.workspace, f"{child_name}.dis.grb")
     grb_c = flopy.mf6.utils.MfGrdFile(fpth)
     mg_c = grb_c.modelgrid
 
@@ -406,7 +408,7 @@ def exact(x):
     # todo: mflistbudget
     # check cumulative balance error from .lst file
     for mname in [parent_name, child_name]:
-        fpth = os.path.join(sim.simpath, f"{mname}.lst")
+        fpth = os.path.join(test.workspace, f"{mname}.lst")
         for line in open(fpth):
             if line.lstrip().startswith("PERCENT"):
                 cumul_balance_error = float(line.split()[3])
@@ -419,7 +421,7 @@ def exact(x):
     # Check on residual, which is stored in diagonal position of
     # flow-ja-face.  Residual should be less than convergence tolerance,
     # or this means the residual term is not added correctly.
-    fpth = os.path.join(sim.simpath, f"{parent_name}.cbc")
+    fpth = os.path.join(test.workspace, f"{parent_name}.cbc")
     cbb = flopy.utils.CellBudgetFile(fpth)
     flow_ja_face = cbb.get_data(idx=0)
     assert (
@@ -433,14 +435,14 @@ def exact(x):
         assert np.allclose(res, 0.0, atol=1.0e-6), errmsg
 
     # Read gwf-gwf observations values
-    fpth = os.path.join(sim.simpath, "gwf_obs.csv")
+    fpth = os.path.join(test.workspace, "gwf_obs.csv")
     with open(fpth) as f:
         lines = f.readlines()
     obsnames = [name for name in lines[0].strip().split(",")[1:]]
     obsvalues = [float(v) for v in lines[1].strip().split(",")[1:]]
 
     # Extract the gwf-gwf flows stored in parent budget file
-    fpth = os.path.join(sim.simpath, f"{parent_name}.cbc")
+    fpth = os.path.join(test.workspace, f"{parent_name}.cbc")
     cbb = flopy.utils.CellBudgetFile(fpth, precision="double")
     parent_exchange_flows = cbb.get_data(
         kstpkper=(0, 0), text="FLOW-JA-FACE", paknam="GWF-GWF_1"
@@ -448,7 +450,7 @@ def exact(x):
     parent_exchange_flows = parent_exchange_flows["q"]
 
     # Extract the gwf-gwf flows stored in child budget file
-    fpth = os.path.join(sim.simpath, f"{child_name}.cbc")
+    fpth = os.path.join(test.workspace, f"{child_name}.cbc")
     cbb = flopy.utils.CellBudgetFile(fpth, precision="double")
     child_exchange_flows = cbb.get_data(
         kstpkper=(0, 0), text="FLOW-JA-FACE", paknam="GWF-GWF_1"
@@ -464,7 +466,7 @@ def exact(x):
     ), "exchange observations do not match child exchange flows"
 
     # Read the lumped boundname observations values
-    fpth = os.path.join(sim.simpath, "gwf_obs_boundnames.csv")
+    fpth = os.path.join(test.workspace, "gwf_obs_boundnames.csv")
     with open(fpth) as f:
         lines = f.readlines()
     obsnames = [name for name in lines[0].strip().split(",")[1:]]
@@ -474,16 +476,13 @@ def exact(x):
     ), "boundname observations do not match expected results"
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, 0, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_heads, idxsim=0
-        ),
-        str(function_tmpdir),
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_ifmod_xt3d02.py b/autotest/test_gwf_ifmod_xt3d02.py
index b95c43b931b..e4876486ae0 100644
--- a/autotest/test_gwf_ifmod_xt3d02.py
+++ b/autotest/test_gwf_ifmod_xt3d02.py
@@ -1,49 +1,49 @@
+"""
+Test the interface model approach.
+It compares the result of a single, strongly anisotropic model
+with XT3D enabled to the equivalent case where the domain is
+decomposed and joined by a GWF-GWF exchange with XT3D applied.
+
+       'refmodel'              'leftmodel'     'rightmodel'
+
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1    VS    1 1 1 1 1   +   1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+
+The head values should always be indentical. All models are
+part of the same solution for convenience.
+In addition, a check on the x,y,z components of specific discharge
+is present. The values of the left submodel are compared to
+the left part of the full model, and similar for right: they
+should be identical. Finally, the budget error is checked.
+"""
+
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
-
-# Test for the interface model approach.
-# It compares the result of a single, strongly anisotropic model
-# with XT3D enabled to the equivalent case where the domain is
-# decomposed and joined by a GWF-GWF exchange with XT3D applied.
-#
-#        'refmodel'              'leftmodel'     'rightmodel'
-#
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1    VS    1 1 1 1 1   +   1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#
-# The head values should always be indentical. All models are
-# part of the same solution for convenience.
-# In addition, a check on the x,y,z components of specific discharge
-# is present. The values of the left submodel are compared to
-# the left part of the full model, and similar for right: they
-# should be identical. Finally, the budget error is checked.
-
-ex = ["ifmod_xt3d02"]
-# global convenience...
+
+cases = ["ifmod_xt3d02"]
 mname_ref = "refmodel"
 mname_left = "leftmodel"
 mname_right = "rightmodel"
 hclose_check = 1e-9
 max_inner_it = 300
-
 useXT3D = True
 
 
 def get_model(idx, dir):
-    name = ex[idx]
+    name = cases[idx]
 
     # parameters and spd
     # tdis
@@ -284,8 +284,8 @@ def get_model(idx, dir):
     return sim
 
 
-def build_model(idx, exdir):
-    sim = get_model(idx, exdir)
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace)
     return sim, None
 
 
@@ -309,27 +309,27 @@ def qxqyqz(fname, nlay, nrow, ncol):
     return qx, qy, qz
 
 
-def compare_to_ref(sim):
+def check_output(idx, test):
     print("comparing heads and spec. discharge to single model reference...")
 
-    fpth = os.path.join(sim.simpath, f"{mname_ref}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_ref}.hds")
     hds = flopy.utils.HeadFile(fpth)
     heads = hds.get_data()
-    fpth = os.path.join(sim.simpath, f"{mname_ref}.cbc")
+    fpth = os.path.join(test.workspace, f"{mname_ref}.cbc")
     nlay, nrow, ncol = heads.shape
     qxb, qyb, qzb = qxqyqz(fpth, nlay, nrow, ncol)
 
-    fpth = os.path.join(sim.simpath, f"{mname_left}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_left}.hds")
     hds = flopy.utils.HeadFile(fpth)
     heads_left = hds.get_data()
-    fpth = os.path.join(sim.simpath, f"{mname_left}.cbc")
+    fpth = os.path.join(test.workspace, f"{mname_left}.cbc")
     nlay, nrow, ncol = heads_left.shape
     qxb_left, qyb_left, qzb_left = qxqyqz(fpth, nlay, nrow, ncol)
 
-    fpth = os.path.join(sim.simpath, f"{mname_right}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_right}.hds")
     hds = flopy.utils.HeadFile(fpth)
     heads_right = hds.get_data()
-    fpth = os.path.join(sim.simpath, f"{mname_right}.cbc")
+    fpth = os.path.join(test.workspace, f"{mname_right}.cbc")
     nlay, nrow, ncol = heads_right.shape
     qxb_right, qyb_right, qzb_right = qxqyqz(fpth, nlay, nrow, ncol)
 
@@ -400,7 +400,7 @@ def compare_to_ref(sim):
 
     # check budget error from .lst file
     for mname in [mname_ref, mname_left, mname_right]:
-        fpth = os.path.join(sim.simpath, f"{mname}.lst")
+        fpth = os.path.join(test.workspace, f"{mname}.lst")
         for line in open(fpth):
             if line.lstrip().startswith("PERCENT"):
                 cumul_balance_error = float(line.split()[3])
@@ -411,16 +411,13 @@ def compare_to_ref(sim):
                 )
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=compare_to_ref, idxsim=idx
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_ifmod_xt3d03.py b/autotest/test_gwf_ifmod_xt3d03.py
new file mode 100644
index 00000000000..e942d03d393
--- /dev/null
+++ b/autotest/test_gwf_ifmod_xt3d03.py
@@ -0,0 +1,446 @@
+"""
+Test the interface model approach.
+It compares the result of a single, strongly anisotropic model
+with XT3D enabled to the equivalent case where the domain is
+decomposed into 4 models connected with GWF-GWF exchanges all
+having XT3D enabled. Note the location of the well W, in the 
+bottom right corner of model "tl" (and also in "ref" of course)
+
+          'ref'                    'tl'            'tr'
+
+                                1 1 1 1 1        1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1        1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1    +   1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1        1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 W        1 1 1 1 1
+   1 1 1 1 W 1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1    VS        +                +
+   1 1 1 1 1 1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1        1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1        1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1    +   1 1 1 1 1
+                                1 1 1 1 1        1 1 1 1 1
+                                1 1 1 1 1        1 1 1 1 1
+
+                                  'bl'             'br'
+
+The head values should always be indentical. All models are
+part of the same solution for convenience.
+In addition, a check on the x,y,z components of specific discharge
+is present. Finally, the budget error is checked.
+"""
+
+import os
+from types import SimpleNamespace
+
+import flopy
+import numpy as np
+import pytest
+
+from framework import TestFramework
+
+cases = ["ifmod_xt3d03"]
+
+hclose_check = 1e-9
+max_inner_it = 300
+useXT3D = True
+
+# model spatial discretization
+nlay = 1
+ncol = 10
+ncol_split = 5
+nrow = 10
+nrow_split = 5
+
+# cell spacing
+delr = 10.0
+delc = 10.0
+area = delr * delc
+
+# shift (hor. and vert.)
+shift_some_x = -20 * delr  # avoids overlap
+shift_x = 5 * delr
+shift_y = 5 * delc
+
+# top/bot of the aquifer
+tops = [0.0, -5.0]
+
+# hydraulic conductivity
+k11 = 10.0
+k22 = 0.1
+k_angle = 45.0
+
+# boundary stress period data
+h_left = -2.0
+h_right = -2.0
+
+# initial head
+h_start = -2.0
+
+# well
+well_id = (0, 4, 4)
+well_rate = -1.0
+
+
+def get_model(idx, dir):
+    name = cases[idx]
+
+    # parameters and spd
+    # tdis
+    nper = 1
+    tdis_rc = []
+    for i in range(nper):
+        tdis_rc.append((1.0, 1, 1))
+
+    # solver data
+    nouter, ninner = 100, max_inner_it
+    hclose, rclose, relax = hclose_check, 1e-3, 0.97
+
+    sim = flopy.mf6.MFSimulation(
+        sim_name=name, version="mf6", exe_name="mf6", sim_ws=dir
+    )
+
+    tdis = flopy.mf6.ModflowTdis(
+        sim, time_units="DAYS", nper=nper, perioddata=tdis_rc
+    )
+
+    ims = flopy.mf6.ModflowIms(
+        sim,
+        print_option="SUMMARY",
+        outer_dvclose=hclose,
+        outer_maximum=nouter,
+        under_relaxation="DBD",
+        inner_maximum=ninner,
+        inner_dvclose=hclose,
+        rcloserecord=rclose,
+        linear_acceleration="BICGSTAB",
+        relaxation_factor=relax,
+    )
+
+    # reference model
+    dis_params = SimpleNamespace(
+        nlay=nlay,
+        nrow=nrow,
+        ncol=ncol,
+        delr=delr,
+        delc=delc,
+        xorigin=shift_some_x,
+        yorigin=0.0,
+        tops=tops,
+    )
+    create_gwf_model(sim, "ref", dis_params)
+
+    # top-left model
+    dis_params.nrow = nrow_split
+    dis_params.ncol = ncol_split
+    dis_params.xorigin = 0.0
+    dis_params.yorigin = shift_y
+    create_gwf_model(sim, "tl", dis_params)
+
+    # bottom-left model
+    dis_params.xorigin = 0.0
+    dis_params.yorigin = 0.0
+    create_gwf_model(sim, "bl", dis_params)
+
+    # top-right model
+    dis_params.xorigin = shift_x
+    dis_params.yorigin = shift_y
+    create_gwf_model(sim, "tr", dis_params)
+
+    # bottom-right model
+    dis_params.xorigin = shift_x
+    dis_params.yorigin = 0.0
+    create_gwf_model(sim, "br", dis_params)
+
+    # two types of exchange data:
+    # tl-tr, bl-br (0 deg)
+    lr_data = [
+        [
+            (0, irow, ncol_split - 1),
+            (0, irow, 0),
+            1,
+            delr / 2.0,
+            delr / 2.0,
+            delc,
+            0.0,
+            delr,
+        ]
+        for irow in range(nrow_split)
+    ]
+    # tl-bl, tr-br (270 deg)
+    tb_data = [
+        [
+            (0, nrow_split - 1, icol),
+            (0, 0, icol),
+            1,
+            delc / 2.0,
+            delc / 2.0,
+            delr,
+            270.0,
+            delc,
+        ]
+        for icol in range(ncol_split)
+    ]
+
+    # set up 4 exchanges
+    # tl-tr
+    gwfgwf = flopy.mf6.ModflowGwfgwf(
+        sim,
+        exgtype="GWF6-GWF6",
+        nexg=len(lr_data),
+        exgmnamea="tl",
+        exgmnameb="tr",
+        exchangedata=lr_data,
+        auxiliary=["ANGLDEGX", "CDIST"],
+        xt3d=useXT3D,
+        filename="tltr.exg",
+    )
+
+    # bl-br
+    gwfgwf = flopy.mf6.ModflowGwfgwf(
+        sim,
+        exgtype="GWF6-GWF6",
+        nexg=len(lr_data),
+        exgmnamea="bl",
+        exgmnameb="br",
+        exchangedata=lr_data,
+        auxiliary=["ANGLDEGX", "CDIST"],
+        xt3d=useXT3D,
+        filename="blbr.exg",
+    )
+
+    # tl-bl
+    gwfgwf = flopy.mf6.ModflowGwfgwf(
+        sim,
+        exgtype="GWF6-GWF6",
+        nexg=len(tb_data),
+        exgmnamea="tl",
+        exgmnameb="bl",
+        exchangedata=tb_data,
+        auxiliary=["ANGLDEGX", "CDIST"],
+        xt3d=useXT3D,
+        filename="tlbl.exg",
+    )
+
+    # tr-br
+    gwfgwf = flopy.mf6.ModflowGwfgwf(
+        sim,
+        exgtype="GWF6-GWF6",
+        nexg=len(tb_data),
+        exgmnamea="tr",
+        exgmnameb="br",
+        exchangedata=tb_data,
+        auxiliary=["ANGLDEGX", "CDIST"],
+        xt3d=useXT3D,
+        filename="trbr.exg",
+    )
+
+    return sim
+
+
+def create_gwf_model(sim, mname, dis_params):
+    gwf = flopy.mf6.ModflowGwf(sim, modelname=mname, save_flows=True)
+
+    dis_params = flopy.mf6.ModflowGwfdis(
+        gwf,
+        nlay=dis_params.nlay,
+        nrow=dis_params.nrow,
+        ncol=dis_params.ncol,
+        delr=dis_params.delr,
+        delc=dis_params.delc,
+        xorigin=dis_params.xorigin,
+        yorigin=dis_params.yorigin,
+        top=dis_params.tops[0],
+        botm=dis_params.tops[1:],
+    )
+
+    # initial conditions
+    ic = flopy.mf6.ModflowGwfic(gwf, strt=h_start)
+
+    # node property flow
+    npf = flopy.mf6.ModflowGwfnpf(
+        gwf,
+        save_specific_discharge=True,
+        xt3doptions=useXT3D,
+        save_flows=True,
+        icelltype=0,
+        k=k11,
+        k22=k22,
+        angle1=k_angle,
+    )
+
+    # chd file
+    left_chd = []
+    right_chd = []
+    if mname == "ref":
+        left_chd = [[(0, irow, 0), h_left] for irow in range(nrow)]
+        right_chd = [[(0, irow, ncol - 1), h_right] for irow in range(nrow)]
+    elif mname == "tl" or mname == "bl":
+        left_chd = [[(0, irow, 0), h_left] for irow in range(nrow_split)]
+        right_chd = []
+    elif mname == "tr" or mname == "br":
+        left_chd = []
+        right_chd = [
+            [(0, irow, ncol_split - 1), h_right] for irow in range(nrow_split)
+        ]
+    chd_data = left_chd + right_chd
+    chd_spd = {0: chd_data}
+    chd = flopy.mf6.ModflowGwfchd(gwf, stress_period_data=chd_spd)
+
+    # well in top-left corner
+    if mname == "ref" or mname == "tl":
+        wel1 = flopy.mf6.ModflowGwfwel(
+            gwf,
+            stress_period_data=[[well_id, well_rate]],
+            print_input=True,
+            print_flows=True,
+            save_flows=False,
+            pname="WEL-1",
+        )
+
+    # output control
+    oc = flopy.mf6.ModflowGwfoc(
+        gwf,
+        head_filerecord=f"{mname}.hds",
+        budget_filerecord=f"{mname}.cbc",
+        headprintrecord=[("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")],
+        saverecord=[("HEAD", "LAST"), ("BUDGET", "LAST")],
+    )
+
+
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace)
+    return sim, None
+
+
+def qxqyqz(fname, nlay, nrow, ncol):
+    nodes = nlay * nrow * ncol
+    cbb = flopy.utils.CellBudgetFile(fname, precision="double")
+    spdis = cbb.get_data(text="DATA-SPDIS")[0]
+    qx = np.ones((nodes), dtype=float) * 1.0e30
+    qy = np.ones((nodes), dtype=float) * 1.0e30
+    qz = np.ones((nodes), dtype=float) * 1.0e30
+    n0 = spdis["node"] - 1
+    qx[n0] = spdis["qx"]
+    qy[n0] = spdis["qy"]
+    qz[n0] = spdis["qz"]
+    qx = qx.reshape(nlay, nrow, ncol)
+    qy = qy.reshape(nlay, nrow, ncol)
+    qz = qz.reshape(nlay, nrow, ncol)
+    qx = np.ma.masked_equal(qx, 1.0e30)
+    qy = np.ma.masked_equal(qy, 1.0e30)
+    qz = np.ma.masked_equal(qz, 1.0e30)
+    return qx, qy, qz
+
+
+def check_output(idx, test):
+    fpth = os.path.join(test.workspace, f"ref.hds")
+    hds = flopy.utils.HeadFile(fpth)
+    heads = hds.get_data()
+    fpth = os.path.join(test.workspace, f"ref.cbc")
+    nlay, nrow, ncol = heads.shape
+    qx, qy, qz = qxqyqz(fpth, nlay, nrow, ncol)
+
+    fpth = os.path.join(test.workspace, f"tl.hds")
+    hds = flopy.utils.HeadFile(fpth)
+    heads_tl = hds.get_data()
+    fpth = os.path.join(test.workspace, f"tl.cbc")
+    nlay, nrow, ncol = heads_tl.shape
+    qx_tl, qy_tl, qz_tl = qxqyqz(fpth, nlay, nrow, ncol)
+
+    fpth = os.path.join(test.workspace, f"tr.hds")
+    hds = flopy.utils.HeadFile(fpth)
+    heads_tr = hds.get_data()
+    fpth = os.path.join(test.workspace, f"tr.cbc")
+    nlay, nrow, ncol = heads_tr.shape
+    qx_tr, qy_tr, qz_tr = qxqyqz(fpth, nlay, nrow, ncol)
+
+    fpth = os.path.join(test.workspace, f"bl.hds")
+    hds = flopy.utils.HeadFile(fpth)
+    heads_bl = hds.get_data()
+    fpth = os.path.join(test.workspace, f"bl.cbc")
+    nlay, nrow, ncol = heads_bl.shape
+    qx_bl, qy_bl, qz_bl = qxqyqz(fpth, nlay, nrow, ncol)
+
+    fpth = os.path.join(test.workspace, f"br.hds")
+    hds = flopy.utils.HeadFile(fpth)
+    heads_br = hds.get_data()
+    fpth = os.path.join(test.workspace, f"br.cbc")
+    nlay, nrow, ncol = heads_br.shape
+    qx_br, qy_br, qz_br = qxqyqz(fpth, nlay, nrow, ncol)
+
+    heads_top = np.append(heads_tl[0], heads_tr[0], axis=1)
+    heads_bot = np.append(heads_bl[0], heads_br[0], axis=1)
+    heads_merged = np.append(heads_top, heads_bot, axis=0)
+
+    # compare heads
+    maxdiff = np.amax(abs(heads - heads_merged))
+    assert (
+        maxdiff < 10 * hclose_check
+    ), "Max. head diff. {} should \
+                     be within solver tolerance (x10): {}".format(
+        maxdiff, 10 * hclose_check
+    )
+
+    # compare spdis-x
+    qx_top = np.append(qx_tl[0], qx_tr[0], axis=1)
+    qx_bot = np.append(qx_bl[0], qx_br[0], axis=1)
+    qx_merged = np.append(qx_top, qx_bot, axis=0)
+
+    maxdiff = np.amax(abs(qx - qx_merged))
+    assert (
+        maxdiff < 10 * hclose_check
+    ), "Max. diff. in spec. discharge (x) {} \
+                     should be within solver tolerance (x10): {}".format(
+        maxdiff, 10 * hclose_check
+    )
+
+    # compare spdis-y
+    qy_top = np.append(qy_tl[0], qy_tr[0], axis=1)
+    qy_bot = np.append(qy_bl[0], qy_br[0], axis=1)
+    qy_merged = np.append(qy_top, qy_bot, axis=0)
+
+    maxdiff = np.amax(abs(qy - qy_merged))
+    assert (
+        maxdiff < 10 * hclose_check
+    ), "Max. diff. in spec. discharge (y) {} \
+                     should be within solver tolerance (x10): {}".format(
+        maxdiff, 10 * hclose_check
+    )
+
+    # compare spdis-z
+    qz_top = np.append(qz_tl[0], qz_tr[0], axis=1)
+    qz_bot = np.append(qz_bl[0], qz_br[0], axis=1)
+    qz_merged = np.append(qz_top, qz_bot, axis=0)
+
+    maxdiff = np.amax(abs(qz - qz_merged))
+    assert (
+        maxdiff < 10 * hclose_check
+    ), "Max. diff. in spec. discharge (z) {} \
+                     should be within solver tolerance (x10): {}".format(
+        maxdiff, 10 * hclose_check
+    )
+
+    # check budget error from .lst file
+    for mname in ["ref", "tl", "tr", "bl", "br"]:
+        fpth = os.path.join(test.workspace, f"{mname}.lst")
+        for line in open(fpth):
+            if line.lstrip().startswith("PERCENT"):
+                cumul_balance_error = float(line.split()[3])
+                assert (
+                    abs(cumul_balance_error) < 0.00001
+                ), "Cumulative balance error = {} for {}, should equal 0.0".format(
+                    cumul_balance_error, mname
+                )
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+    )
+    test.run()
diff --git a/autotest/test_gwf_ims_rcm_reorder.py b/autotest/test_gwf_ims_rcm_reorder.py
index b6b587e5b38..c5f39010094 100644
--- a/autotest/test_gwf_ims_rcm_reorder.py
+++ b/autotest/test_gwf_ims_rcm_reorder.py
@@ -3,11 +3,12 @@
 import flopy
 import pytest
 from flopy.utils.compare import eval_bud_diff
+
 from framework import TestFramework
-from simulation import TestSimulation
 
 paktest = "ims"
-ex = ["ims_rcm"]
+cases = ["ims_rcm"]
+cmp_prefix = "mf6"
 
 # spatial discretization data
 nlay, nrow, ncol = 2, 5, 30
@@ -26,7 +27,7 @@ def build_model(idx, ws):
     tdis_rc = [(1.0, 1, 1.0)]
 
     # build MODFLOW 6 files
-    name = ex[idx]
+    name = cases[idx]
     sim = flopy.mf6.MFSimulation(
         sim_name=name,
         version="mf6",
@@ -41,7 +42,7 @@ def build_model(idx, ws):
         perioddata=tdis_rc,
     )
 
-    if not ws.endswith("mf6"):
+    if not str(ws).endswith(cmp_prefix):
         reordering_method = "rcm"
     else:
         reordering_method = None
@@ -111,29 +112,24 @@ def build_model(idx, ws):
     return sim
 
 
-def build_models(idx, base_ws):
-    sim = build_model(idx, base_ws)
-
-    ws = os.path.join(base_ws, "mf6")
-    mc = build_model(idx, ws)
-
-    return sim, mc
-
+def build_models(idx, test):
+    return build_model(idx, test.workspace), build_model(
+        idx, os.path.join(test.workspace, cmp_prefix)
+    )
 
-def eval_flows(sim):
-    name = sim.name
-    print("evaluating flow results..." f"({name})")
 
-    fpth = os.path.join(sim.simpath, f"{name}.dis.grb")
+def check_output(idx, test):
+    name = test.name
+    fpth = os.path.join(test.workspace, f"{name}.dis.grb")
     ia = flopy.mf6.utils.MfGrdFile(fpth).ia
 
-    fpth = os.path.join(sim.simpath, f"{name}.cbc")
+    fpth = os.path.join(test.workspace, f"{name}.cbc")
     b0 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
-    fpth = os.path.join(sim.simpath, "mf6", f"{name}.cbc")
+    fpth = os.path.join(test.workspace, cmp_prefix, f"{name}.cbc")
     b1 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
-    fpth = os.path.join(sim.simpath, f"{name}.cbc.cmp.out")
+    fpth = os.path.join(test.workspace, f"{name}.cbc.cmp.out")
     eval_bud_diff(fpth, b0, b1, ia=ia)
 
     # close the budget files
@@ -141,20 +137,13 @@ def eval_flows(sim):
     b1.close()
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_models, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_flows,
-            idxsim=0,
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_lak_bedleak.py b/autotest/test_gwf_lak_bedleak.py
new file mode 100644
index 00000000000..6a3a42d6830
--- /dev/null
+++ b/autotest/test_gwf_lak_bedleak.py
@@ -0,0 +1,179 @@
+import os
+
+import flopy
+import numpy as np
+import pytest
+
+from framework import DNODATA, TestFramework
+
+cases = ["bedleak", "bedleak_fail", "bedleak_none"]
+
+
+def build_models(idx, test):
+    nlay, nrow, ncol = 1, 10, 10
+    nper = 1
+    perlen = [
+        1.0,
+    ]
+    nstp = [
+        1,
+    ]
+    tsmult = [
+        1.0,
+    ]
+
+    lenx = 300.0
+    delr = delc = lenx / float(nrow)
+    strt = 100.0
+
+    nouter, ninner = 100, 300
+    hclose, rclose, relax = 1e-9, 1e-3, 0.97
+
+    tdis_rc = []
+    for i in range(nper):
+        tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
+
+    name = cases[idx]
+
+    # build MODFLOW 6 files
+    ws = test.workspace
+    sim = flopy.mf6.MFSimulation(
+        sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
+    )
+    # create tdis package
+    tdis = flopy.mf6.ModflowTdis(
+        sim,
+        time_units="DAYS",
+        nper=nper,
+        perioddata=tdis_rc,
+    )
+
+    # create iterative model solution and register the gwf model with it
+    ims = flopy.mf6.ModflowIms(
+        sim,
+        print_option="SUMMARY",
+        outer_dvclose=hclose,
+        outer_maximum=nouter,
+        under_relaxation="DBD",
+        inner_maximum=ninner,
+        inner_dvclose=hclose,
+        rcloserecord=rclose,
+        linear_acceleration="BICGSTAB",
+        scaling_method="NONE",
+        reordering_method="NONE",
+        relaxation_factor=relax,
+    )
+
+    # create gwf model
+    gwf = flopy.mf6.ModflowGwf(sim, modelname=name)
+
+    dis = flopy.mf6.ModflowGwfdis(
+        gwf,
+        nlay=nlay,
+        nrow=nrow,
+        ncol=ncol,
+        delr=delr,
+        delc=delc,
+        top=90.0,
+        botm=0.0,
+    )
+
+    # initial conditions
+    ic = flopy.mf6.ModflowGwfic(gwf, strt=strt)
+
+    # node property flow
+    npf = flopy.mf6.ModflowGwfnpf(
+        gwf, save_flows=True, icelltype=1, k=1.0, k33=0.01
+    )
+    # storage
+    sto = flopy.mf6.ModflowGwfsto(
+        gwf,
+        save_flows=True,
+        iconvert=1,
+        ss=0.0,
+        sy=0.1,
+        steady_state={0: True},
+    )
+
+    # chd files
+    chdlist0 = []
+    chdlist0.append([(0, 0, 0), 100.0])
+    chdlist0.append([(0, nrow - 1, ncol - 1), 95.0])
+
+    chdspdict = {0: chdlist0}
+    chd = flopy.mf6.ModflowGwfchd(
+        gwf,
+        stress_period_data=chdspdict,
+        save_flows=False,
+    )
+
+    # lak package
+    if "fail" in name:
+        bedleak = -100.0
+    elif "none" in name:
+        bedleak = "none"
+    else:
+        bedleak = DNODATA
+
+    # <ifno> <strt> <nlakeconn> [<aux(naux)>] [<boundname>]
+    packagedata = [
+        [0, 100.0, 1, "lake1"],
+        [1, 100.0, 1, "lake2"],
+    ]
+    # <ifno> <iconn> <cellid(ncelldim)> <claktype> <bedleak> <belev> <telev> <connlen> <connwidth>
+    connectiondata = [
+        [0, 0, (0, 1, 1), "vertical", bedleak, 0.0, 0.0, 0.0, 0.0],
+        [1, 0, (0, 2, 2), "vertical", bedleak, 0.0, 0.0, 0.0, 0.0],
+    ]
+    lak = flopy.mf6.ModflowGwflak(
+        gwf,
+        boundnames=True,
+        surfdep=1.0,
+        print_input=True,
+        print_stage=True,
+        print_flows=True,
+        save_flows=True,
+        budget_filerecord=f"{name}.lak.bud",
+        nlakes=len(packagedata),
+        packagedata=packagedata,
+        connectiondata=connectiondata,
+    )
+    # lak.remove()
+
+    # output control
+    oc = flopy.mf6.ModflowGwfoc(
+        gwf,
+        budget_filerecord=f"{name}.cbc",
+        headprintrecord=[("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")],
+        saverecord=[("BUDGET", "ALL")],
+        printrecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
+    )
+
+    return sim, None
+
+
+def check_output(idx, test):
+    name = cases[idx]
+
+    # lak budget
+    if "fail" not in name:
+        fpth = os.path.join(test.workspace, f"{name}.lak.bud")
+        bobj = flopy.utils.CellBudgetFile(fpth, precision="double")
+        bobj.list_unique_records()
+        records = bobj.get_data(text="GWF")
+        for r in records:
+            assert np.allclose(r["q"][0], -4.79616347e-12)
+            assert np.allclose(r["q"][1], -6.19237994e-12)
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        xfail="fail" in str(function_tmpdir),
+    )
+    test.run()
diff --git a/autotest/test_gwf_lak_wetlakbedarea01.py b/autotest/test_gwf_lak_wetlakbedarea01.py
index cba89465af3..5a0043a0cc0 100644
--- a/autotest/test_gwf_lak_wetlakbedarea01.py
+++ b/autotest/test_gwf_lak_wetlakbedarea01.py
@@ -1,19 +1,21 @@
-# A simple 2 layer by 1 row by 2 column model.  Upper-right cell is the only 
-# active LAK cell.  Lake starts out initially dry and then is wetted by a 
-# rising water table.  A constant head boundary in the lower left corner cell
-# is used to raise water table. This autotest checks to ensure that the wetted
-# areas between the lake and the 2 connected cells (1 vertical, 1 horizontal)
-# is correct.
+"""
+A simple 2 layer by 1 row by 2 column model.  Upper-right cell is the only
+active LAK cell.  Lake starts out initially dry and then is wetted by a
+rising water table.  A constant head boundary in the lower left corner cell
+is used to raise water table. This autotest checks to ensure that the wetted
+areas between the lake and the 2 connected cells (1 vertical, 1 horizontal)
+is correct.
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["lak-1cellkbd"]
+cases = ["lak-1cellkbd"]
 
 # Model units
 length_units = "feet"
@@ -29,15 +31,15 @@
 k33 = [1179.0, 1179.0]
 ss = 3e-4
 sy = 0.2
-chd_lr = 9.0 
+chd_lr = 9.0
 lak_strt = 9.0  # Starting lake stage
 lak_bedleak = 10.0  # Lakebed leakance
 
-idomain = np.full((nlay, nrow, ncol), 1) 
+idomain = np.full((nlay, nrow, ncol), 1)
 idomain[0, 0, 1] = 0  # deactivate upper-right corner of 2x1x2 model
 
-top = 20.
-botm = [10., 0.]
+top = 20.0
+botm = [10.0, 0.0]
 
 # define delr and delc
 delr = 10.0
@@ -62,7 +64,18 @@
 
 # Prepare constant head boundary data information
 chd_spd = {}
-chd_inc = [9.999999, 10.0, 10.000001, 10.00001, 10.0001, 10.001, 10.01, 10.1, 10.11, 10.12]
+chd_inc = [
+    9.999999,
+    10.0,
+    10.000001,
+    10.00001,
+    10.0001,
+    10.001,
+    10.01,
+    10.1,
+    10.11,
+    10.12,
+]
 for i, t in enumerate(range(len(perlen))):
     chd_spd.update({i: [nlay - 1, nrow - 1, 0, chd_inc[i]]})
 
@@ -85,7 +98,7 @@
     [10.25, 0.0280716, 0.4, 0.4],
     [10.3, 0.068889924, 0.5, 0.5],
     [10.35, 0.1690610, 0.6, 0.6],
-    [10.4, 0.4148885490, 0.7, 0.7]
+    [10.4, 0.4148885490, 0.7, 0.7],
 ]
 
 # Set solver parameters
@@ -95,12 +108,14 @@
 rclose = 1e-6
 relax = 0.97
 
+
 def resolve_lvl(stg, hd, toplay):
     ss = min(stg, toplay)
     hh = min(hd, toplay)
     thk = max(ss, hh)
     return thk
 
+
 def calc_qSat(top, bot, thk):
     teps = 1e-6
     tbmin = 0.0
@@ -135,13 +150,11 @@ def calc_qSat(top, bot, thk):
 
     return y
 
-#
-# MODFLOW 6 flopy GWF object
-#
-def build_model(idx, dir):
+
+def build_models(idx, test):
     # Base simulation and model name and workspace
-    ws = dir
-    name = ex[idx]
+    ws = test.workspace
+    name = cases[idx]
 
     print("Building model...{}".format(name))
 
@@ -159,7 +172,7 @@ def build_model(idx, dir):
         ats_filerecord=ats_filerecord,
         nper=nper,
         perioddata=tdis_rc,
-        time_units=time_units
+        time_units=time_units,
     )
 
     if True:
@@ -231,18 +244,34 @@ def build_model(idx, dir):
 
     # Instantiate constant head boundary package
     flopy.mf6.ModflowGwfchd(gwf, stress_period_data=chd_spd)
-    
+
     # Instantiate LAK package
     lak_conn = []
     if use_embedded_lak:
-        lak_conn.append([0, 0, (0, 0, 1), 'embeddedv', lak_bedleak, 0.0, 0.0, 1.0, 0.0])
+        lak_conn.append(
+            [0, 0, (0, 0, 1), "embeddedv", lak_bedleak, 0.0, 0.0, 1.0, 0.0]
+        )
     else:
-        lak_conn.append([0, 0, (0, 0, 0), 'horizontal', lak_bedleak, 10.0, 20.0, 10.0, 10.0])
-        lak_conn.append([0, 1, (1, 0, 1), 'vertical', lak_bedleak, 0.0, 0.0, 0.0, 0.0])
+        lak_conn.append(
+            [
+                0,
+                0,
+                (0, 0, 0),
+                "horizontal",
+                lak_bedleak,
+                10.0,
+                20.0,
+                10.0,
+                10.0,
+            ]
+        )
+        lak_conn.append(
+            [0, 1, (1, 0, 1), "vertical", lak_bedleak, 0.0, 0.0, 0.0, 0.0]
+        )
 
     lak_packagedata = [0, lak_strt, len(lak_conn)]
     budpth = f"{gwfname}.lak.cbc"
-    tab6_filename = '{}.laktab'.format(gwfname)
+    tab6_filename = "{}.laktab".format(gwfname)
     if use_embedded_lak:
         # LAK package input requires tables option when using embedded lakes.
         lak = flopy.mf6.ModflowGwflak(
@@ -277,7 +306,7 @@ def build_model(idx, dir):
             budget_filerecord=budpth,
             time_conversion=86400,
             length_conversion=3.28081,
-            #surfdep=0.05,
+            # surfdep=0.05,
             pname="LAK-1",
             filename="{}.lak".format(gwfname),
         )
@@ -289,23 +318,22 @@ def build_model(idx, dir):
         ]
     }
     lak.obs.initialize(
-        filename=obs_file,
-        digits=10,
-        print_input=True,
-        continuous=obs_dict
+        filename=obs_file, digits=10, print_input=True, continuous=obs_dict
     )
     if use_embedded_lak:
         tabinput = []
         for itm in lak_tab:
             tabinput.append([itm[0], itm[1], itm[2], itm[3]])
-    
-        laktab = flopy.mf6.ModflowUtllaktab(gwf,
-                                            nrow=len(tabinput),
-                                            ncol=len(tabinput[0]),
-                                            table=tabinput,
-                                            filename=tab6_filename,
-                                            pname='LAK_tab',
-                                            parent_file=lak)
+
+        laktab = flopy.mf6.ModflowUtllaktab(
+            gwf,
+            nrow=len(tabinput),
+            ncol=len(tabinput[0]),
+            table=tabinput,
+            filename=tab6_filename,
+            pname="LAK_tab",
+            parent_file=lak,
+        )
 
     # Instantiate output control package
     head_filerecord = "{}.hds".format(gwfname)
@@ -315,38 +343,38 @@ def build_model(idx, dir):
         head_filerecord=head_filerecord,
         budget_filerecord=budget_filerecord,
         saverecord=[("HEAD", "LAST"), ("BUDGET", "LAST")],
-        printrecord=[("HEAD", "ALL")]
+        printrecord=[("HEAD", "ALL")],
     )
 
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # read flow results from model
-    name = ex[sim.idxsim]
+    name = cases[idx]
     gwfname = "gwf-" + name
 
     # read flow results from model
-    sim1 = flopy.mf6.MFSimulation.load(sim_ws=sim.simpath, load_only=["dis"])
+    sim1 = flopy.mf6.MFSimulation.load(
+        sim_ws=test.workspace, load_only=["dis"]
+    )
     gwf = sim1.get_model(gwfname)
 
     # get final lake stage
-    lk_pth0 = os.path.join(sim.simpath, f"{gwfname}.lak.obs.csv")
+    lk_pth0 = os.path.join(test.workspace, f"{gwfname}.lak.obs.csv")
     lkstg = np.genfromtxt(lk_pth0, names=True, delimiter=",")
     lkstg_time = lkstg["time"].tolist()
     lkstg_val = lkstg["STAGE"].tolist()
 
     # Store only the values at the end of the time step
-    idx = [i for i, val in enumerate(lkstg_time) if not val.is_integer()]
-    for i in idx[::-1]:
+    indices = [i for i, val in enumerate(lkstg_time) if not val.is_integer()]
+    for i in indices[::-1]:
         lkstg_time.pop(i)
         lkstg_val.pop(i)
 
     # Get heads
     fname = gwfname + ".hds"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
 
     hdobj = flopy.utils.binaryfile.HeadFile(fname, precision="double")
@@ -354,7 +382,7 @@ def eval_results(sim):
 
     # Get lake/gwf exchange information
     fname = gwfname + ".lak.cbc"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
 
     lakobj = flopy.utils.binaryfile.CellBudgetFile(fname, precision="double")
@@ -370,8 +398,10 @@ def eval_results(sim):
     wetted_out = np.array(wetted_out)
 
     # Compare MF6 output to answer calculated here
-    msg = 'Compare value written by MF6 to a value calculated here based on ' \
-          'either lake stage or gw head'
+    msg = (
+        "Compare value written by MF6 to a value calculated here based on "
+        "either lake stage or gw head"
+    )
     for tm in np.arange(wetted_out.shape[0]):
         for conn in np.arange(wetted_out.shape[1]):
             stg = lkstg_val[tm]
@@ -410,17 +440,14 @@ def eval_results(sim):
     monotonicIncrease = np.diff(wetted_out[2:, 0])
     assert np.all(monotonicIncrease > 0), msg
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_lak_wetlakbedarea02.py b/autotest/test_gwf_lak_wetlakbedarea02.py
index 91e83afc917..b72807e67df 100644
--- a/autotest/test_gwf_lak_wetlakbedarea02.py
+++ b/autotest/test_gwf_lak_wetlakbedarea02.py
@@ -1,17 +1,19 @@
-# An adaptation of the LAK package problem 1 supplemented with an additional
-# layer that has variable thinkness to help test that the shared wetted area
-# between a lakebed and groundwater cells in contact with the lake are written
-# to the LAK cbc output file correctly.
+"""
+An adaptation of the LAK package problem 1 supplemented with an additional
+layer that has variable thinkness to help test that the shared wetted area
+between a lakebed and groundwater cells in contact with the lake are written
+to the LAK cbc output file correctly.
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["lak-wetlkbd"]
+cases = ["lak-wetlkbd"]
 
 # Model units
 length_units = "feet"
@@ -201,10 +203,10 @@ def calc_qSat(top, bot, thk):
 #
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     # Base simulation and model name and workspace
-    ws = dir
-    name = ex[idx]
+    ws = test.workspace
+    name = cases[idx]
 
     print("Building model...{}".format(name))
 
@@ -330,25 +332,25 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # read flow results from model
-    name = ex[sim.idxsim]
+    name = cases[idx]
     gwfname = "gwf-" + name
 
     # read flow results from model
-    sim1 = flopy.mf6.MFSimulation.load(sim_ws=sim.simpath, load_only=["dis"])
+    sim1 = flopy.mf6.MFSimulation.load(
+        sim_ws=test.workspace, load_only=["dis"]
+    )
     gwf = sim1.get_model(gwfname)
 
     # get final lake stage
-    lk_pth0 = os.path.join(sim.simpath, f"{gwfname}.lak.obs.csv")
+    lk_pth0 = os.path.join(test.workspace, f"{gwfname}.lak.obs.csv")
     lkstg = np.genfromtxt(lk_pth0, names=True, delimiter=",")
     lkstg_val = lkstg["STAGE"]
 
     # Get heads
     fname = gwfname + ".hds"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
 
     hdobj = flopy.utils.binaryfile.HeadFile(fname, precision="double")
@@ -356,7 +358,7 @@ def eval_results(sim):
 
     # Get lake/gwf exchange information
     fname = gwfname + ".lak.cbc"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
 
     lakobj = flopy.utils.binaryfile.CellBudgetFile(fname, precision="double")
@@ -373,7 +375,7 @@ def eval_results(sim):
         "The wetted interfacial areas saved in the binary output file "
         "(.cbc) do not match the values calculated in the autotest script"
     )
-    for idx, itm in enumerate(lak_con):
+    for ii, itm in enumerate(lak_con):
         k, i, j = itm[2]
         ctype = itm[3]
         if ctype[0] == "h":
@@ -393,20 +395,16 @@ def eval_results(sim):
             width = delc[i]
             warea = length * width
 
-        assert np.isclose(warea, checks_out[idx], atol=1e-5), msg
+        assert np.isclose(warea, checks_out[ii], atol=1e-5), msg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_laket.py b/autotest/test_gwf_laket.py
index b180ff3baed..91f00bd8d48 100644
--- a/autotest/test_gwf_laket.py
+++ b/autotest/test_gwf_laket.py
@@ -1,17 +1,15 @@
-# Test for checking lak evaporation.
+"""Test for checking lak evaporation."""
 
 
 import os
-import shutil
-import sys
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = [
+cases = [
     "gwf_laket01",
     "gwf_laket02",
     "gwf_laket03",
@@ -23,7 +21,7 @@
 
 
 def get_model(idx, ws):
-    name = ex[idx]
+    name = cases[idx]
     nlay = 1
     nrow = 1
     ncol = 1
@@ -112,7 +110,7 @@ def get_model(idx, ws):
     ]
     nlakeconn = 1
 
-    # pak_data = [lakeno, strt, nlakeconn]
+    # pak_data = [ifno, strt, nlakeconn]
     pak_data = [(0, lakestage[idx], nlakeconn)]
 
     belev = top
@@ -175,18 +173,14 @@ def get_model(idx, ws):
     return sim
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     # build MODFLOW 6 files
-    sim = get_model(idx, dir)
-
+    sim = get_model(idx, test.workspace)
     return sim, None
 
 
-def eval_laket(sim):
-    msg = "Evaluating Lake ET. "
-
-    fpth = os.path.join(sim.simpath, f"{sim.name}.lak.obs.csv")
+def check_output(idx, test):
+    fpth = os.path.join(test.workspace, f"{test.name}.lak.obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -206,7 +200,7 @@ def eval_laket(sim):
                 (8.000000000000, 5.2000000000000028, -0.1),
                 (9.000000000000, 5.1000000000000032, -0.1),
                 (10.00000000000, 5.0000000000000036, -0.1),
-                (11.00000000000, 5.0000000000000000,  0.0),
+                (11.00000000000, 5.0000000000000000, 0.0),
                 (12.00000000000, 5.0999999999999996, -0.1),
                 (13.00000000000, 5.1999999999999993, -0.1),
                 (14.00000000000, 5.2999999999999989, -0.1),
@@ -257,10 +251,10 @@ def eval_laket(sim):
                 (5.000000000000, 5.1402629856607369, -0.1),
                 (6.000000000000, 5.0345111305663464, -0.1),
                 (7.000000000000, 5.0000000000000000, -0.0345111305663464),
-                (8.000000000000, 5.0000000000000000,  0.0),
-                (9.000000000000, 5.0000000000000000,  0.0),
-                (10.00000000000, 5.0000000000000000,  0.0),
-                (11.00000000000, 5.0000000000000000,  0.0),
+                (8.000000000000, 5.0000000000000000, 0.0),
+                (9.000000000000, 5.0000000000000000, 0.0),
+                (10.00000000000, 5.0000000000000000, 0.0),
+                (11.00000000000, 5.0000000000000000, 0.0),
                 (12.00000000000, 5.0857142857142854, -0.1),
                 (13.00000000000, 5.1591836734693874, -0.1),
                 (14.00000000000, 5.2221574344023320, -0.1),
@@ -277,41 +271,34 @@ def eval_laket(sim):
         ),
     }
 
-    if sim.idxsim in (
+    if idx in (
         0,
         1,
         2,
     ):
-        evap_compare = np.allclose(obs[sim.idxsim]["evap"], tc["EVAP"])
-        stage_compare = np.allclose(obs[sim.idxsim]["stage"], tc["LAKESTAGE"])
+        evap_compare = np.allclose(obs[idx]["evap"], tc["EVAP"])
+        stage_compare = np.allclose(obs[idx]["stage"], tc["LAKESTAGE"])
     else:
         evap_compare = True
         stage_compare = True
 
-    sim.success = True
+    test.success = True
     if not evap_compare:
-        sim.success = False
+        test.success = False
         msg += f" Lake evaporation comparison failed."
     if not stage_compare:
-        sim.success = False
+        test.success = False
         msg += f" Lake stage comparison failed."
-    assert sim.success, msg
+    assert test.success, msg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_laket,
-            idxsim=idx,
-            mf6_regression=False,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_lakobs01.py b/autotest/test_gwf_lakobs01.py
index 8cfc8ff2de9..cff4ab1881d 100644
--- a/autotest/test_gwf_lakobs01.py
+++ b/autotest/test_gwf_lakobs01.py
@@ -1,21 +1,19 @@
-# Test for checking lak observation input.  The following observation types:
-# 'lak', 'wetted-area', and 'conductance,' require that ID2 be provided when
-# ID is an integer corresponding to a lake number and not BOUNDNAME.
-# See table in LAK Package section of mf6io.pdf for an explanation of ID,
-# ID2, and Observation Type.
+"""
+Test for checking lak observation input.  The following observation types:
+'lak', 'wetted-area', and 'conductance,' require that ID2 be provided when
+ID is an integer corresponding to a lake number and not BOUNDNAME.
+See table in LAK Package section of mf6io.pdf for an explanation of ID,
+ID2, and Observation Type.
+"""
 
 
 import os
-import shutil
-import sys
 
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-ex = "gwf_lakobs_01a"
+cases = "gwf_lakobs_01a"
 gwf = None
 
 
@@ -54,7 +52,7 @@ def build_model(dir, exe):
     nouter, ninner = 700, 300
     hclose, rclose, relax = 1e-8, 1e-6, 0.97
 
-    name = ex
+    name = cases
 
     # build MODFLOW 6 files
     sim = flopy.mf6.MFSimulation(
@@ -138,7 +136,7 @@ def build_model(dir, exe):
             irch[i, j] = k + 1
     nlakeconn = len(lake_vconnect)
 
-    # pak_data = [lakeno, strt, nlakeconn]
+    # pak_data = [ifno, strt, nlakeconn]
     initial_stage = 0.1
     pak_data = [(0, initial_stage, nlakeconn)]
 
@@ -206,13 +204,8 @@ def build_model(dir, exe):
 
 
 def test_mf6model(function_tmpdir, targets):
-    mf6 = targets["mf6"]
-
-    # initialize testing framework
-    test = TestFramework()
-
     # build the models
-    sim = build_model(str(function_tmpdir), mf6)
+    sim = build_model(str(function_tmpdir), targets["mf6"])
 
     # write model input
     sim.write_simulation()
@@ -235,8 +228,8 @@ def test_mf6model(function_tmpdir, targets):
     )
 
     # fix the error and attempt to rerun model
-    orig_fl = str(function_tmpdir / (ex + ".lak.obs"))
-    new_fl = str(function_tmpdir / (ex + ".lak.obs.new"))
+    orig_fl = str(function_tmpdir / (cases + ".lak.obs"))
+    new_fl = str(function_tmpdir / (cases + ".lak.obs.new"))
     sr = open(orig_fl, "r")
     sw = open(new_fl, "w")
 
diff --git a/autotest/test_gwf_libmf6_evt01.py b/autotest/test_gwf_libmf6_evt01.py
index b962f653f30..067e7ac7ae4 100644
--- a/autotest/test_gwf_libmf6_evt01.py
+++ b/autotest/test_gwf_libmf6_evt01.py
@@ -1,8 +1,6 @@
 """
-MODFLOW 6 Autotest
-Test the bmi which is used update the calculate a head-based pumping rate that
-is equivalent to use of the evapotranspiration package in the
-non-bmi simulation.
+Test bmi with a head-based pumping rate equivalent to
+the evapotranspiration package in a non-bmi simulation.
 """
 
 import os
@@ -10,11 +8,11 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
 from modflowapi import ModflowApi
-from simulation import TestSimulation
 
-ex = ["libgwf_evt01"]
+from framework import TestFramework
+
+cases = ["libgwf_evt01"]
 
 # et variables
 et_max = 0.1
@@ -128,14 +126,14 @@ def get_model(ws, name, bmi=False):
     return sim
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     # build MODFLOW 6 files
-    ws = dir
-    name = ex[idx]
+    ws = test.workspace
+    name = cases[idx]
     sim = get_model(ws, name)
 
     # build comparison model
-    ws = os.path.join(dir, "libmf6")
+    ws = os.path.join(test.workspace, "libmf6")
     mc = get_model(ws, name, bmi=True)
 
     return sim, mc
@@ -153,7 +151,7 @@ def head2et_wellrate(h):
 
 
 def api_func(exe, idx, model_ws=None):
-    name = ex[idx].upper()
+    name = cases[idx].upper()
     if model_ws is None:
         model_ws = "."
     output_file_path = os.path.join(model_ws, "mfsim.stdout")
@@ -184,7 +182,7 @@ def api_func(exe, idx, model_ws=None):
     max_iter = mf6.get_value(mxit_tag)
 
     # get copy of well data
-    well_tag = mf6.get_var_address("BOUND", name, "WEL_0")
+    well_tag = mf6.get_var_address("Q", name, "WEL_0")
     well = mf6.get_value(well_tag)
 
     # check NPF type
@@ -202,7 +200,6 @@ def api_func(exe, idx, model_ws=None):
     # model time loop
     idx = 0
     while current_time < end_time:
-
         # get dt and prepare for non-linear iterations
         dt = mf6.get_time_step()
         mf6.prepare_time_step(dt)
@@ -212,10 +209,9 @@ def api_func(exe, idx, model_ws=None):
         mf6.prepare_solve()
 
         while kiter < max_iter:
-
             # update well rate
             twell[:] = head2et_wellrate(head[0])
-            well[:, 0] = twell[:]
+            well[:] = twell[:]
             mf6.set_value(well_tag, well)
 
             # solve with updated well rate
@@ -254,16 +250,13 @@ def api_func(exe, idx, model_ws=None):
     return True, open(output_file_path).readlines()
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, idxsim=idx, api_func=api_func
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        api_func=lambda exe, ws: api_func(exe, idx, ws),
     )
+    test.run()
diff --git a/autotest/test_gwf_libmf6_ghb01.py b/autotest/test_gwf_libmf6_ghb01.py
index 43e7ce239f5..4809b430c45 100644
--- a/autotest/test_gwf_libmf6_ghb01.py
+++ b/autotest/test_gwf_libmf6_ghb01.py
@@ -1,21 +1,19 @@
 """
-MODFLOW 6 Autotest
-Test the api which is used update to set the simulate the effect of a general
-head boundary (ghb) at the downgradient end of the model with a head below the
-bottom of the cell. The api results are compared to a non-api simulation that
-uses the well package to simulate the effect of the same ghb. This is a
-possible solution to https://github.com/MODFLOW-USGS/modflow6/issues/724
+Simulate the effect of a general head boundary (ghb) at the downgradient end
+of the model with a head below the bottom of the cell. Compare api result to
+a non-api simulation using the well package to simulate an equivalent ghb.
+Possible solution to https://github.com/MODFLOW-USGS/modflow6/issues/724
 """
 import os
 
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
 from modflowapi import ModflowApi
-from simulation import TestSimulation
 
-ex = ["libgwf_ghb01"]
+from framework import TestFramework
+
+cases = ["libgwf_ghb01"]
 
 # temporal discretization
 nper = 10
@@ -162,15 +160,14 @@ def get_model(ws, name, api=False):
     return sim
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     # build MODFLOW 6 files
-    ws = dir
-    name = ex[idx]
-
+    ws = test.workspace
+    name = cases[idx]
     sim = get_model(ws, name)
 
     # build comparison model with zeroed values
-    ws = os.path.join(dir, "libmf6")
+    ws = os.path.join(test.workspace, "libmf6")
     mc = get_model(ws, name, api=True)
 
     return sim, mc
@@ -183,7 +180,7 @@ def api_ghb_pak(hcof, rhs):
 
 
 def api_func(exe, idx, model_ws=None):
-    name = ex[idx].upper()
+    name = cases[idx].upper()
     if model_ws is None:
         model_ws = "."
     output_file_path = os.path.join(model_ws, "mfsim.stdout")
@@ -228,7 +225,6 @@ def api_func(exe, idx, model_ws=None):
 
     # model time loop
     while current_time < end_time:
-
         # get dt
         dt = mf6.get_time_step()
 
@@ -277,16 +273,13 @@ def api_func(exe, idx, model_ws=None):
     return True, open(output_file_path).readlines()
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, idxsim=idx, api_func=api_func
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        targets=targets,
+        api_func=lambda exe, ws: api_func(exe, idx, ws),
     )
+    test.run()
diff --git a/autotest/test_gwf_libmf6_ifmod01.py b/autotest/test_gwf_libmf6_ifmod01.py
index 51577ed622f..6ffe87935c3 100644
--- a/autotest/test_gwf_libmf6_ifmod01.py
+++ b/autotest/test_gwf_libmf6_ifmod01.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 Test the interface model approach for coupling two gwf models.
 We need the API for this, as the interface model is hidden and
 not present in any of the output. The setup is two coupled
@@ -16,19 +15,16 @@
 
 import flopy
 import pytest
-from framework import TestFramework
 from modflowapi import ModflowApi
-from simulation import TestSimulation
 
-ex = ["libgwf_ifmod01"]
+from framework import TestFramework
 
-# global convenience...
+cases = ["libgwf_ifmod01"]
 name_left = "leftmodel"
 name_right = "rightmodel"
 
 
 def get_model(dir, name):
-
     useXT3D = True
 
     # parameters and spd
@@ -197,14 +193,14 @@ def get_model(dir, name):
     return sim
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     # build MODFLOW 6 files
-    ws = dir
-    name = ex[idx]
+    ws = test.workspace
+    name = cases[idx]
     sim = get_model(ws, name)
 
     # build comparison model
-    ws = os.path.join(dir, "libmf6")
+    ws = os.path.join(test.workspace, "libmf6")
     sim_compare = get_model(ws, name)
 
     return sim, sim_compare
@@ -307,17 +303,13 @@ def check_interface_models(mf6):
                 ), "AREA in interface model does not match"
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, idxsim=idx, api_func=api_func
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        targets=targets,
+        api_func=lambda exe, ws: api_func(exe, idx, ws),
     )
+    test.run()
diff --git a/autotest/test_gwf_libmf6_ifmod02.py b/autotest/test_gwf_libmf6_ifmod02.py
index 5faa7d76512..b9f6462ddd3 100644
--- a/autotest/test_gwf_libmf6_ifmod02.py
+++ b/autotest/test_gwf_libmf6_ifmod02.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 Test the interface model approach for an inhomogeneous coupling 
 of three gwf models using the API. One exchange will have XT3D
 enabled (Exg1) and the other one (Exg2) doesn't. And the top-left
@@ -41,11 +40,11 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
 from modflowapi import ModflowApi
-from simulation import TestSimulation
 
-ex = ["libgwf_ifmod02"]
+from framework import TestFramework
+
+cases = ["libgwf_ifmod02"]
 
 # global convenience...
 name_tl = "topleft"
@@ -54,7 +53,6 @@
 
 
 def get_model(dir, name):
-
     # parameters and spd
     # tdis
     nper = 1
@@ -291,14 +289,14 @@ def get_model(dir, name):
     return sim
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     # build MODFLOW 6 files
-    ws = dir
-    name = ex[idx]
+    ws = test.workspace
+    name = cases[idx]
     sim = get_model(ws, name)
 
     # build comparison model
-    ws = os.path.join(dir, "libmf6")
+    ws = os.path.join(test.workspace, "libmf6")
     sim_compare = get_model(ws, name)
 
     return sim, sim_compare
@@ -403,17 +401,14 @@ def check_interface_models(mf6):
     )
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 @pytest.mark.developmode
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, idxsim=idx, api_func=api_func
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        targets=targets,
+        api_func=lambda exe, ws: api_func(exe, idx, ws),
     )
+    test.run()
diff --git a/autotest/test_gwf_libmf6_ifmod03.py b/autotest/test_gwf_libmf6_ifmod03.py
index c238d269110..f5d24a342db 100644
--- a/autotest/test_gwf_libmf6_ifmod03.py
+++ b/autotest/test_gwf_libmf6_ifmod03.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 Test the interface model approach for coupling two DIS
 models where one is translated and rotated in space:
 
@@ -31,11 +30,11 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
 from modflowapi import ModflowApi
-from simulation import TestSimulation
 
-ex = ["libgwf_ifmod03"]
+from framework import TestFramework
+
+cases = ["libgwf_ifmod03"]
 
 # global convenience...
 name_left = "left"
@@ -44,12 +43,11 @@
 
 
 def get_model(dir, name):
-
     # parameters and spd
     # tdis
     nper = 1
     tdis_rc = []
-    for i in range(nper):
+    for _ in range(nper):
         tdis_rc.append((1.0, 1, 1))
 
     # solver data
@@ -208,14 +206,14 @@ def get_model(dir, name):
     return sim
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     # build MODFLOW 6 files
-    ws = dir
-    name = ex[idx]
+    ws = test.workspace
+    name = cases[idx]
     sim = get_model(ws, name)
 
     # build comparison model
-    ws = os.path.join(dir, "libmf6")
+    ws = os.path.join(test.workspace, "libmf6")
     sim_compare = get_model(ws, name)
 
     return sim, sim_compare
@@ -289,16 +287,13 @@ def check_interface_models(mf6):
     assert abs(ymax - ymin) < 1e-6
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, idxsim=idx, api_func=api_func
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        api_func=lambda exe, ws: api_func(exe, idx, ws),
     )
+    test.run()
diff --git a/autotest/test_gwf_libmf6_rch01.py b/autotest/test_gwf_libmf6_rch01.py
index bb8252e8cff..b7ef4c50e6c 100644
--- a/autotest/test_gwf_libmf6_rch01.py
+++ b/autotest/test_gwf_libmf6_rch01.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 Test to make sure that recharge is passed to the highest active layer and
 verify that recharge is in the highest active layer by looking at the
 individual budget terms.  For this test, there are two layers and five
@@ -13,11 +12,11 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
 from modflowapi import ModflowApi
-from simulation import TestSimulation
 
-ex = ["libgwf_rch01"]
+from framework import TestFramework
+
+cases = ["libgwf_rch01"]
 
 # recharge package name
 rch_pname = "RCH-1"
@@ -135,21 +134,21 @@ def get_model(ws, name, rech):
     return sim
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     # build MODFLOW 6 files
-    ws = dir
-    name = ex[idx]
+    ws = test.workspace
+    name = cases[idx]
     sim = get_model(ws, name, rech=rch_spd)
 
     # build comparison model
-    ws = os.path.join(dir, "libmf6")
+    ws = os.path.join(test.workspace, "libmf6")
     mc = get_model(ws, name, rech=0.0)
 
     return sim, mc
 
 
 def api_func(exe, idx, model_ws=None):
-    name = ex[idx].upper()
+    name = cases[idx].upper()
     if model_ws is None:
         model_ws = "."
 
@@ -177,13 +176,12 @@ def api_func(exe, idx, model_ws=None):
     max_iter = mf6.get_value(mxit_tag)
 
     # get copy of recharge array
-    rch_tag = mf6.get_var_address("BOUND", name, rch_pname)
+    rch_tag = mf6.get_var_address("RECHARGE", name, rch_pname)
     new_recharge = mf6.get_value(rch_tag)
 
     # model time loop
     idx = 0
     while current_time < end_time:
-
         # get dt and prepare for non-linear iterations
         dt = mf6.get_time_step()
         mf6.prepare_time_step(dt)
@@ -193,7 +191,7 @@ def api_func(exe, idx, model_ws=None):
         mf6.prepare_solve()
 
         # update recharge
-        new_recharge[:, 0] = rch_spd[idx] * area
+        new_recharge[:] = rch_spd[idx]
         mf6.set_value(rch_tag, new_recharge)
 
         while kiter < max_iter:
@@ -232,16 +230,13 @@ def api_func(exe, idx, model_ws=None):
     return True, open(output_file_path).readlines()
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, idxsim=idx, api_func=api_func
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        api_func=lambda exe, ws: api_func(exe, idx, ws),
     )
+    test.run()
diff --git a/autotest/test_gwf_libmf6_rch02.py b/autotest/test_gwf_libmf6_rch02.py
index 1e7a5797a3e..fc1b4c6fdf9 100644
--- a/autotest/test_gwf_libmf6_rch02.py
+++ b/autotest/test_gwf_libmf6_rch02.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 Test the bmi which is used to calculate a recharge rate that results in a
 simulated head in the center of the model domain to be equal to the
 simulated head in the non-bmi simulation.
@@ -10,11 +9,11 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
 from modflowapi import ModflowApi
-from simulation import TestSimulation
 
-ex = ["libgwf_rch02"]
+from framework import TestFramework
+
+cases = ["libgwf_rch02"]
 
 # recharge package name
 rch_pname = "RCH-1"
@@ -153,26 +152,25 @@ def get_model(ws, name, exe, rech=rch_spd):
     return sim
 
 
-def build_model(idx, dir, exe):
+def build_models(idx, test):
     # build MODFLOW 6 files
-    ws = dir
-    name = ex[idx]
-    sim = get_model(ws, name, exe)
+    ws = test.workspace
+    name = cases[idx]
+    sim = get_model(ws, name, "mf6")
 
     # build comparison model
-    ws = os.path.join(dir, "libmf6")
-    mc = get_model(ws, name, exe, rech=0.0)
+    ws = os.path.join(test.workspace, "libmf6")
+    mc = get_model(ws, name, "mf6", rech=0.0)
 
     return sim, mc
 
 
 def run_perturbation(mf6, max_iter, recharge, tag, rch):
-
     mf6.prepare_solve()
     kiter = 0
     while kiter < max_iter:
         # update recharge
-        recharge[:, 0] = rch * area
+        recharge[:] = rch
         mf6.set_value(tag, recharge)
         # solve with updated well rate
         has_converged = mf6.solve()
@@ -185,7 +183,7 @@ def run_perturbation(mf6, max_iter, recharge, tag, rch):
 def api_func(exe, idx, model_ws=None):
     print("\nBMI implementation test:")
 
-    name = ex[idx].upper()
+    name = cases[idx].upper()
     init_wd = os.path.abspath(os.getcwd())
     if model_ws is not None:
         os.chdir(model_ws)
@@ -193,7 +191,7 @@ def api_func(exe, idx, model_ws=None):
     output_file_path = os.path.join(model_ws, "mfsim.stdout")
 
     # get the observations from the standard run
-    fpth = os.path.join("..", f"{ex[idx]}.head.obs.csv")
+    fpth = os.path.join("..", f"{cases[idx]}.head.obs.csv")
     hobs = np.genfromtxt(fpth, delimiter=",", names=True)["H1_6_6"]
 
     try:
@@ -222,7 +220,7 @@ def api_func(exe, idx, model_ws=None):
     max_iter = mf6.get_value(mxit_tag)
 
     # get copy of recharge array
-    rch_tag = mf6.get_var_address("BOUND", name, rch_pname)
+    rch_tag = mf6.get_var_address("RECHARGE", name, rch_pname)
     new_recharge = mf6.get_value(rch_tag).copy()
 
     # determine initial recharge value
@@ -232,7 +230,6 @@ def api_func(exe, idx, model_ws=None):
     # model time loop
     idx = 0
     while current_time < end_time:
-
         # target head
         htarget = hobs[idx]
 
@@ -308,20 +305,13 @@ def api_func(exe, idx, model_ws=None):
     return True, open(output_file_path).readlines()
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(
-        lambda i, d: build_model(i, d, targets["mf6"]),
-        idx,
-        str(function_tmpdir),
-    )
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, idxsim=idx, api_func=api_func
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        targets=targets,
+        api_func=lambda exe, ws: api_func(exe, idx, ws),
     )
+    test.run()
diff --git a/autotest/test_gwf_libmf6_riv01.py b/autotest/test_gwf_libmf6_riv01.py
index 0fc8dd7e598..ef42e2e29d7 100644
--- a/autotest/test_gwf_libmf6_riv01.py
+++ b/autotest/test_gwf_libmf6_riv01.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 Test the bmi which is used update to set the river stages to
 the same values as they are in the non-bmi simulation.
 """
@@ -8,11 +7,11 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
 from modflowapi import ModflowApi
-from simulation import TestSimulation
 
-ex = ["libgwf_riv01"]
+from framework import TestFramework
+
+cases = ["libgwf_riv01"]
 
 # temporal discretization
 nper = 10
@@ -129,10 +128,10 @@ def get_model(ws, name, riv_spd):
     return sim
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     # build MODFLOW 6 files
-    ws = dir
-    name = ex[idx]
+    ws = test.workspace
+    name = cases[idx]
 
     # create river data
     rd = [
@@ -146,7 +145,7 @@ def build_model(idx, dir):
     sim = get_model(ws, name, riv_spd={0: rd, 5: rd2})
 
     # build comparison model with zeroed values
-    ws = os.path.join(dir, "libmf6")
+    ws = os.path.join(test.workspace, "libmf6")
     rd_bmi = [[(0, 0, icol), 999.0, 999.0, 0.0] for icol in range(1, ncol - 1)]
     mc = get_model(ws, name, riv_spd={0: rd_bmi})
 
@@ -154,7 +153,7 @@ def build_model(idx, dir):
 
 
 def api_func(exe, idx, model_ws=None):
-    name = ex[idx].upper()
+    name = cases[idx].upper()
     if model_ws is None:
         model_ws = "."
 
@@ -178,13 +177,16 @@ def api_func(exe, idx, model_ws=None):
     end_time = mf6.get_end_time()
 
     # get copy of (multi-dim) array with river parameters
-    riv_tag = mf6.get_var_address("BOUND", name, riv_packname)
-    new_spd = mf6.get_value(riv_tag)
+    stage_tag = mf6.get_var_address("STAGE", name, riv_packname)
+    cond_tag = mf6.get_var_address("COND", name, riv_packname)
+    rbot_tag = mf6.get_var_address("RBOT", name, riv_packname)
+    new_stage = mf6.get_value(stage_tag)
+    new_cond = mf6.get_value(cond_tag)
+    new_rbot = mf6.get_value(rbot_tag)
 
     # model time loop
     idx = 0
     while current_time < end_time:
-
         # get dt
         dt = mf6.get_time_step()
 
@@ -192,16 +194,18 @@ def api_func(exe, idx, model_ws=None):
         mf6.prepare_time_step(dt)
 
         # set the RIV data through the BMI
+        # change cond and rbot data
+        new_cond[:] = [riv_cond]
+        new_rbot[:] = [riv_bot]
+        mf6.set_value(cond_tag, new_cond)
+        mf6.set_value(rbot_tag, new_rbot)
+        # change stage data
         if current_time < 5:
-            # set columns of BOUND data (we're setting entire columns of the
-            # 2D array for convenience, setting only the value for the active
-            # stress period should work too)
-            new_spd[:] = [riv_stage, riv_cond, riv_bot]
-            mf6.set_value(riv_tag, new_spd)
+            new_stage[:] = [riv_stage]
+            mf6.set_value(stage_tag, new_stage)
         else:
-            # change only stage data
-            new_spd[:] = [riv_stage2, riv_cond, riv_bot]
-            mf6.set_value(riv_tag, new_spd)
+            new_stage[:] = [riv_stage2]
+            mf6.set_value(stage_tag, new_stage)
 
         kiter = 0
         mf6.prepare_solve()
@@ -242,16 +246,13 @@ def api_func(exe, idx, model_ws=None):
     return True, open(output_file_path).readlines()
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, idxsim=idx, api_func=api_func
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        api_func=lambda exe, ws: api_func(exe, idx, ws),
     )
+    test.run()
diff --git a/autotest/test_gwf_libmf6_riv02.py b/autotest/test_gwf_libmf6_riv02.py
index eb3337c0561..2f94f7717e5 100644
--- a/autotest/test_gwf_libmf6_riv02.py
+++ b/autotest/test_gwf_libmf6_riv02.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 Test the api which is used set hcof and rhs in api package compare to river
 package in the non-api simulation.
 """
@@ -8,11 +7,11 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
 from modflowapi import ModflowApi
-from simulation import TestSimulation
 
-ex = ["libgwf_riv02"]
+from framework import TestFramework
+
+cases = ["libgwf_riv02"]
 
 # temporal discretization
 nper = 10
@@ -132,10 +131,10 @@ def get_model(ws, name, riv_spd, api=False):
     return sim
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     # build MODFLOW 6 files
-    ws = dir
-    name = ex[idx]
+    ws = test.workspace
+    name = cases[idx]
 
     # create river data
     rd = [
@@ -149,7 +148,7 @@ def build_model(idx, dir):
     sim = get_model(ws, name, riv_spd={0: rd, 5: rd2})
 
     # build comparison model with zeroed values
-    ws = os.path.join(dir, "libmf6")
+    ws = os.path.join(test.workspace, "libmf6")
     rd_api = [[(0, 0, icol), 999.0, 999.0, 0.0] for icol in range(1, ncol - 1)]
     mc = get_model(ws, name, riv_spd={0: rd_api}, api=True)
 
@@ -168,7 +167,7 @@ def api_riv_pak(stage, h, hcof, rhs):
 
 
 def api_func(exe, idx, model_ws=None):
-    name = ex[idx].upper()
+    name = cases[idx].upper()
     if model_ws is None:
         model_ws = "."
 
@@ -216,7 +215,6 @@ def api_func(exe, idx, model_ws=None):
     # model time loop
     idx = 0
     while current_time < end_time:
-
         # get dt
         dt = mf6.get_time_step()
 
@@ -273,16 +271,13 @@ def api_func(exe, idx, model_ws=None):
     return True, open(output_file_path).readlines()
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, idxsim=idx, api_func=api_func
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        api_func=lambda exe, ws: api_func(exe, idx, ws),
     )
+    test.run()
diff --git a/autotest/test_gwf_libmf6_sto01.py b/autotest/test_gwf_libmf6_sto01.py
index 4cbe8caeb68..24283ffa3ee 100644
--- a/autotest/test_gwf_libmf6_sto01.py
+++ b/autotest/test_gwf_libmf6_sto01.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 Test the bmi set_value function, which is used update
 the Sy=0 value with same Sy used to calculate SC2 in
 the non-bmi simulation.
@@ -10,11 +9,11 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
 from modflowapi import ModflowApi
-from simulation import TestSimulation
 
-ex = ["libgwf_sto01"]
+from framework import TestFramework
+
+cases = ["libgwf_sto01"]
 
 # average recharge rate
 avg_rch = 0.001
@@ -138,21 +137,21 @@ def get_model(ws, name, sy):
     return sim
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     # build MODFLOW 6 files
-    ws = dir
-    name = ex[idx]
+    ws = test.workspace
+    name = cases[idx]
     sim = get_model(ws, name, sy=sy_val)
 
     # build comparison model
-    ws = os.path.join(dir, "libmf6")
+    ws = os.path.join(test.workspace, "libmf6")
     mc = get_model(ws, name, sy=0.0)
 
     return sim, mc
 
 
 def api_func(exe, idx, model_ws=None):
-    name = ex[idx].upper()
+    name = cases[idx].upper()
     if model_ws is None:
         model_ws = "."
 
@@ -185,7 +184,6 @@ def api_func(exe, idx, model_ws=None):
     # model time loop
     idx = 0
     while current_time < end_time:
-
         # run the time step
         try:
             mf6.update()
@@ -209,16 +207,13 @@ def api_func(exe, idx, model_ws=None):
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, idxsim=idx, api_func=api_func
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        api_func=lambda exe, ws: api_func(exe, idx, ws),
     )
+    test.run()
diff --git a/autotest/test_gwf_maw01.py b/autotest/test_gwf_maw01.py
new file mode 100644
index 00000000000..d94a41d37bf
--- /dev/null
+++ b/autotest/test_gwf_maw01.py
@@ -0,0 +1,189 @@
+import os
+from types import SimpleNamespace
+
+import flopy
+import numpy as np
+import pytest
+
+cases = ["maw01", "maw01nwt", "maw01nwtur"]
+budtol = 1e-2
+bud_lst = ["GWF_IN", "GWF_OUT", "RATE_IN", "RATE_OUT"]
+krylov = ["CG", "BICGSTAB", "BICGSTAB"]
+newton = [None, "NEWTON", "NEWTON UNDER_RELAXATION"]
+nlay = 1
+nrow = 1
+ncol = 3
+nper = 3
+delr = 300
+delc = 300
+perlen = 3 * [1]
+nstp = 3 * [1]
+tsmult = 3 * [1]
+well = SimpleNamespace(
+    observations={"maw_obs.csv": [("mh1", "head", 1)]},
+    packagedata=[[0, 0.1, 50.0, 100.0, "THIEM", 1]],
+    connectiondata=[[0, 0, (0, 0, 1), 100.0, 50.0, 1.0, 0.1]],
+    perioddata=[[0, "rate", 0.0]],
+)
+strt = 100
+hk = 1
+nouter = 100
+ninner = 300
+hclose = 1e-9
+rclose = 1e-3
+relaxation_factor = 1
+compare = False
+
+
+def build_model(idx, ws, mf6):
+    name = cases[idx]
+    sim = flopy.mf6.MFSimulation(
+        sim_name=name,
+        version="mf6",
+        exe_name=mf6,
+        sim_ws=ws,
+    )
+
+    # create tdis package
+    tdis_rc = [(perlen[i], nstp[i], tsmult[i]) for i in range(nper)]
+    tdis = flopy.mf6.ModflowTdis(
+        sim, time_units="DAYS", nper=nper, perioddata=tdis_rc
+    )
+
+    # create gwf model
+    gwf = flopy.mf6.MFModel(
+        sim,
+        model_type="gwf6",
+        modelname=name,
+        model_nam_file=f"{name}.nam",
+    )
+    gwf.name_file.newtonoptions = newton[idx]
+
+    # create iterative model solution and register the gwf model with it
+    ims = flopy.mf6.ModflowIms(
+        sim,
+        print_option="SUMMARY",
+        outer_dvclose=hclose,
+        outer_maximum=nouter,
+        under_relaxation="NONE",
+        inner_maximum=ninner,
+        inner_dvclose=hclose,
+        rcloserecord=rclose,
+        linear_acceleration=krylov[idx],
+        scaling_method="NONE",
+        reordering_method="NONE",
+        relaxation_factor=relaxation_factor,
+    )
+    sim.register_ims_package(ims, [gwf.name])
+
+    dis = flopy.mf6.ModflowGwfdis(
+        gwf,
+        nlay=nlay,
+        nrow=nrow,
+        ncol=ncol,
+        delr=delr,
+        delc=delc,
+        top=100.0,
+        botm=0.0,
+        idomain=1,
+        filename=f"{name}.dis",
+    )
+
+    # initial conditions
+    ic = flopy.mf6.ModflowGwfic(gwf, strt=strt, filename=f"{name}.ic")
+
+    # node property flow
+    npf = flopy.mf6.ModflowGwfnpf(
+        gwf,
+        save_flows=True,
+        icelltype=1,
+        k=hk,
+        k33=hk,
+        filename=f"{name}.npf",
+    )
+    # storage
+    sto = flopy.mf6.ModflowGwfsto(
+        gwf,
+        save_flows=True,
+        iconvert=1,
+        ss=0.0,
+        sy=0.1,
+        steady_state={0: True},
+        # transient={1: False},
+        filename=f"{name}.sto",
+    )
+
+    # chd files
+    chdlist0 = []
+    chdlist0.append([(0, 0, 0), 100.0])
+    chdlist0.append([(0, 0, 2), 100.0])
+
+    chdlist1 = []
+    chdlist1.append([(0, 0, 0), 25.0])
+    chdlist1.append([(0, 0, 2), 25.0])
+
+    chdspdict = {0: chdlist0, 1: chdlist1, 2: chdlist0}
+    chd = flopy.mf6.ModflowGwfchd(
+        gwf,
+        stress_period_data=chdspdict,
+        save_flows=False,
+        filename=f"{name}.chd",
+    )
+
+    # wel files
+    # wel = flopy.mf6.ModflowGwfwel(gwf, print_input=True, print_flows=True,
+    #                              maxbound=len(ws),
+    #                              periodrecarray=wd6,
+    #                              save_flows=False)
+    # MAW
+    maw = flopy.mf6.ModflowGwfmaw(
+        gwf,
+        filename=f"{name}.maw",
+        print_input=True,
+        print_head=True,
+        print_flows=True,
+        save_flows=True,
+        observations=well.observations,
+        packagedata=well.packagedata,
+        connectiondata=well.connectiondata,
+        perioddata=well.perioddata,
+    )
+
+    # output control
+    oc = flopy.mf6.ModflowGwfoc(
+        gwf,
+        budget_filerecord=f"{name}.cbc",
+        head_filerecord=f"{name}.hds",
+        headprintrecord=[("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")],
+        saverecord=[("HEAD", "ALL")],
+        printrecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
+        filename=f"{name}.oc",
+    )
+
+    return sim, None
+
+
+def check_output(workspace):
+    # MODFLOW 6 maw results
+    fpth = os.path.join(workspace, "maw_obs.csv")
+    tc = np.genfromtxt(fpth, names=True, delimiter=",")
+
+    # create known results array
+    tc0 = np.array([100.0, 25.0, 100.0])
+
+    # calculate maximum absolute error
+    diff = tc["MH1"] - tc0
+    diffmax = np.abs(diff).max()
+    dtol = 1e-9
+    msg = f"maximum absolute maw head difference {diffmax}"
+    assert diffmax < dtol, msg + f" exceeds tolerance {dtol}"
+    print(msg)
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    ws = str(function_tmpdir)
+    sim, _ = build_model(idx, ws, targets["mf6"])
+    sim.write_simulation()
+    sim.run_simulation()
+    check_output(ws)
diff --git a/autotest/test_gwf_maw02.py b/autotest/test_gwf_maw02.py
new file mode 100644
index 00000000000..bd9f42704f3
--- /dev/null
+++ b/autotest/test_gwf_maw02.py
@@ -0,0 +1,289 @@
+import os
+from types import SimpleNamespace
+
+import flopy
+import numpy as np
+import pytest
+
+cases = ["maw02"]
+budtol = 1e-2
+bud_lst = ["GWF_IN", "GWF_OUT", "RATE_IN", "RATE_OUT"]
+krylov = "CG"
+nlay = 1
+nrow = 1
+ncol = 3
+nper = 5
+delr = 300
+delc = 300
+perlen = 5 * [1]
+nstp = 5 * [1]
+tsmult = 5 * [1]
+well = SimpleNamespace(
+    observations={"maw_obs.csv": [("mh1", "head", 1)]},
+    packagedata=[
+        [0, 0.1, 0.0, 100.0, "THIEM", 1],
+        [1, 0.1, 0.0, 100.0, "THIEM", 1],
+    ],
+    connectiondata=[
+        [0, 0, (0, 0, 1), 100.0, 0.0, 1.0, 0.1],
+        [1, 0, (0, 0, 1), 100.0, 0.0, 1.0, 0.1],
+    ],
+    perioddata={
+        0: [
+            [0, "rate", -20.0],
+            [0, "status", "inactive"],
+            [0, "rate_scaling", 1.0, 15.0],
+            [1, "rate", -30.0],
+            [1, "status", "inactive"],
+            [1, "rate_scaling", 5.0, 15.0],
+        ],
+        1: [
+            [0, "rate", -110.0],
+            [0, "status", "active"],
+            [1, "rate", -130.0],
+            [1, "status", "active"],
+        ],
+        3: [[0, "status", "inactive"]],
+        4: [[0, "status", "active"]],
+    },
+)
+strt = 100
+hk = 1
+nouter = 100
+ninner = 300
+hclose = 1e-9
+rclose = 1e-3
+relaxation_factor = 1
+compare = False
+
+
+def build_model(idx, ws, mf6):
+    name = cases[idx]
+    sim = flopy.mf6.MFSimulation(
+        sim_name=name, version="mf6", exe_name=mf6, sim_ws=ws
+    )
+
+    # create tdis package
+    tdis_rc = [(perlen[i], nstp[i], tsmult[i]) for i in range(nper)]
+    tdis = flopy.mf6.ModflowTdis(
+        sim, time_units="DAYS", nper=nper, perioddata=tdis_rc
+    )
+
+    # create gwf model
+    gwf = flopy.mf6.MFModel(
+        sim,
+        model_type="gwf6",
+        modelname=name,
+        model_nam_file=f"{name}.nam",
+    )
+
+    # create iterative model solution and register the gwf model with it
+    ims = flopy.mf6.ModflowIms(
+        sim,
+        print_option="SUMMARY",
+        outer_dvclose=hclose,
+        outer_maximum=nouter,
+        under_relaxation="NONE",
+        inner_maximum=ninner,
+        inner_dvclose=hclose,
+        rcloserecord=rclose,
+        linear_acceleration=krylov,
+        scaling_method="NONE",
+        reordering_method="NONE",
+        relaxation_factor=relaxation_factor,
+    )
+    sim.register_ims_package(ims, [gwf.name])
+
+    dis = flopy.mf6.ModflowGwfdis(
+        gwf,
+        nlay=nlay,
+        nrow=nrow,
+        ncol=ncol,
+        delr=delr,
+        delc=delc,
+        top=100.0,
+        botm=0.0,
+        idomain=1,
+        filename=f"{name}.dis",
+    )
+
+    # initial conditions
+    ic = flopy.mf6.ModflowGwfic(gwf, strt=strt, filename=f"{name}.ic")
+
+    # node property flow
+    npf = flopy.mf6.ModflowGwfnpf(
+        gwf,
+        save_flows=True,
+        icelltype=1,
+        k=hk,
+        k33=hk,
+        filename=f"{name}.npf",
+    )
+    # storage
+    sto = flopy.mf6.ModflowGwfsto(
+        gwf,
+        save_flows=True,
+        iconvert=1,
+        ss=0.0,
+        sy=0.1,
+        steady_state={0: True},
+        # transient={1: False},
+        filename=f"{name}.sto",
+    )
+
+    # chd files
+    chdlist0 = []
+    chdlist0.append([(0, 0, 0), 100.0])
+    chdlist0.append([(0, 0, 2), 100.0])
+
+    chdlist1 = []
+    chdlist1.append([(0, 0, 0), 25.0])
+    chdlist1.append([(0, 0, 2), 25.0])
+
+    chdspdict = {0: chdlist0, 1: chdlist1, 2: chdlist0}
+    chd = flopy.mf6.ModflowGwfchd(
+        gwf,
+        stress_period_data=chdspdict,
+        save_flows=False,
+        filename=f"{name}.chd",
+    )
+
+    # MAW
+    maw = flopy.mf6.ModflowGwfmaw(
+        gwf,
+        filename=f"{name}.maw",
+        budget_filerecord=f"{name}.maw.cbc",
+        print_input=True,
+        print_head=True,
+        print_flows=True,
+        save_flows=True,
+        observations=well.observations,
+        packagedata=well.packagedata,
+        connectiondata=well.connectiondata,
+        perioddata=well.perioddata,
+        pname="MAW-1",
+    )
+
+    # output control
+    oc = flopy.mf6.ModflowGwfoc(
+        gwf,
+        budget_filerecord=f"{name}.cbc",
+        head_filerecord=f"{name}.hds",
+        headprintrecord=[("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")],
+        saverecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
+        printrecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
+        filename=f"{name}.oc",
+    )
+
+    return sim, None
+
+
+def eval_results(name, workspace):
+    shape3d = (nlay, nrow, ncol)
+    size3d = nlay * nrow * ncol
+
+    # get results from listing file
+    fpth = os.path.join(workspace, f"{os.path.basename(name)}.lst")
+    budl = flopy.utils.Mf6ListBudget(
+        fpth, budgetkey="MAW-1 BUDGET FOR ENTIRE MODEL AT END OF TIME STEP"
+    )
+    names = list(bud_lst)
+    d0 = budl.get_budget(names=names)[0]
+    dtype = d0.dtype
+    nbud = d0.shape[0]
+
+    # get results from cbc file
+    cbc_bud = ["GWF", "RATE"]
+    d = np.recarray(nbud, dtype=dtype)
+    for key in bud_lst:
+        d[key] = 0.0
+    fpth = os.path.join(workspace, f"{os.path.basename(name)}.maw.cbc")
+    cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
+    kk = cobj.get_kstpkper()
+    times = cobj.get_times()
+    cbc_vals = []
+    for idx, (k, t) in enumerate(zip(kk, times)):
+        for text in cbc_bud:
+            qin = 0.0
+            qout = 0.0
+            v = cobj.get_data(kstpkper=k, text=text)[0]
+            if isinstance(v, np.recarray):
+                vt = np.zeros(size3d, dtype=float)
+                wq = []
+                for jdx, node in enumerate(v["node"]):
+                    vt[node - 1] += v["q"][jdx]
+                    wq.append(v["q"][jdx])
+                v = vt.reshape(shape3d)
+                if text == cbc_bud[-1]:
+                    cbc_vals.append(wq)
+            for kk in range(v.shape[0]):
+                for ii in range(v.shape[1]):
+                    for jj in range(v.shape[2]):
+                        vv = v[kk, ii, jj]
+                        if vv < 0.0:
+                            qout -= vv
+                        else:
+                            qin += vv
+            d["totim"][idx] = t
+            d["time_step"][idx] = k[0]
+            d["stress_period"] = k[1]
+            key = f"{text}_IN"
+            d[key][idx] = qin
+            key = f"{text}_OUT"
+            d[key][idx] = qout
+
+    maw_vals = [
+        [0.000, 0.000],
+        [-106.11303563809453, -96.22598985147631],
+        [-110.000, -130.000],
+        [0.0, -130.000],
+        [-110.000, -130.000],
+    ]
+
+    # evaluate if well rates in cbc file are equal to expected values
+    diffv = []
+    for ovs, svs in zip(maw_vals, cbc_vals):
+        for ov, sv in zip(ovs, svs):
+            diffv.append(ov - sv)
+    diffv = np.abs(np.array(diffv)).max()
+    msg = f"\nmaximum absolute maw rate difference     ({diffv})\n"
+
+    # calculate difference between water budget items in the lst and cbc files
+    diff = np.zeros((nbud, len(bud_lst)), dtype=float)
+    for idx, key in enumerate(bud_lst):
+        diff[:, idx] = d0[key] - d[key]
+    diffmax = np.abs(diff).max()
+    msg += f"maximum absolute total-budget difference ({diffmax}) "
+
+    # write summary
+    fpth = os.path.join(workspace, f"{os.path.basename(name)}.bud.cmp.out")
+    f = open(fpth, "w")
+    for i in range(diff.shape[0]):
+        if i == 0:
+            line = f"{'TIME':>10s}"
+            for idx, key in enumerate(bud_lst):
+                line += f"{key + '_LST':>25s}"
+                line += f"{key + '_CBC':>25s}"
+                line += f"{key + '_DIF':>25s}"
+            f.write(line + "\n")
+        line = f"{d['totim'][i]:10g}"
+        for idx, key in enumerate(bud_lst):
+            line += f"{d0[key][i]:25g}"
+            line += f"{d[key][i]:25g}"
+            line += f"{diff[i, idx]:25g}"
+        f.write(line + "\n")
+    f.close()
+
+    assert diffmax < budtol, (
+        msg + f"diffmax {diffmax} exceeds tolerance {budtol}"
+    )
+    assert diffv < budtol, msg + f"diffv {diffv} exceeds tolerance {budtol}"
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    ws = str(function_tmpdir)
+    sim, _ = build_model(idx, ws, targets["mf6"])
+    sim.write_simulation()
+    sim.run_simulation()
+    eval_results(name, ws)
diff --git a/autotest/test_gwf_maw03.py b/autotest/test_gwf_maw03.py
new file mode 100644
index 00000000000..3f37660960e
--- /dev/null
+++ b/autotest/test_gwf_maw03.py
@@ -0,0 +1,214 @@
+import os
+from types import SimpleNamespace
+
+import flopy
+import numpy as np
+import pytest
+
+cases = ["maw03a", "maw03b", "maw03c"]
+budtol = 1e-2
+bud_lst = ["GWF_IN", "GWF_OUT", "RATE_IN", "RATE_OUT"]
+
+
+def well3(name):
+    perioddata = {
+        "maw03a": [
+            (0, "rate", 2000.0),
+        ],
+        "maw03b": [(0, "rate", 2000.0), (0, "head_limit", 0.4)],
+        "maw03c": [(0, "rate", 2000.0), (0, "rate_scaling", 0.0, 1.0)],
+    }
+    wellbottom = -1000
+    return SimpleNamespace(
+        observations={
+            f"{name}.maw.obs.csv": [
+                ("m1head", "head", (0,)),
+                ("m1rate", "rate", (0,)),
+            ]  # is this index one-based? Not if in a tuple
+        },
+        packagedata=[[0, 0.15, wellbottom, 0.0, "THIEM", 1]],
+        connectiondata=[[0, 0, (0, 50, 50), 0.0, wellbottom, 0.0, 0.0]],
+        perioddata=perioddata[name],
+    )
+
+
+krylov = "CG"
+nlay = 1
+nrow = 101
+ncol = 101
+nper = 1
+delr = 142
+delc = 142
+perlen = [1000]
+nstp = [50]
+tsmult = [1.2]
+strt = 0
+hk = 10
+nouter = 100
+ninner = 100
+hclose = 1e-6
+rclose = 1e-6
+relaxation_factor = 1
+compare = False
+
+
+def build_model(idx, ws, mf6):
+    top = 0.0
+    botm = [-1000.0]
+
+    tdis_rc = []
+    for i in range(nper):
+        tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
+
+    name = cases[idx]
+    sim = flopy.mf6.MFSimulation(sim_name=name, sim_ws=ws, exe_name=mf6)
+
+    # create tdis package
+    tdis = flopy.mf6.ModflowTdis(
+        sim, time_units="DAYS", nper=nper, perioddata=tdis_rc
+    )
+
+    # create gwf model
+    gwf = flopy.mf6.MFModel(
+        sim,
+        model_type="gwf6",
+        modelname=name,
+        model_nam_file=f"{name}.nam",
+    )
+
+    # create iterative model solution and register the gwf model with it
+    ims = flopy.mf6.ModflowIms(
+        sim,
+        print_option="SUMMARY",
+        outer_dvclose=hclose,
+        outer_maximum=nouter,
+        under_relaxation="NONE",
+        inner_maximum=ninner,
+        inner_dvclose=hclose,
+        rcloserecord=rclose,
+        linear_acceleration=krylov,
+        scaling_method="NONE",
+        reordering_method="NONE",
+        relaxation_factor=relaxation_factor,
+    )
+    sim.register_ims_package(ims, [gwf.name])
+
+    dis = flopy.mf6.ModflowGwfdis(
+        gwf,
+        nlay=nlay,
+        nrow=nrow,
+        ncol=ncol,
+        delr=delr,
+        delc=delc,
+        top=top,
+        botm=botm,
+        idomain=1,
+        filename=f"{name}.dis",
+    )
+
+    # initial conditions
+    ic = flopy.mf6.ModflowGwfic(gwf, strt=strt, filename=f"{name}.ic")
+
+    # node property flow
+    npf = flopy.mf6.ModflowGwfnpf(
+        gwf,
+        save_flows=True,
+        icelltype=1,
+        k=hk,
+        k33=hk,
+        filename=f"{name}.npf",
+    )
+
+    # storage
+    sto = flopy.mf6.ModflowGwfsto(
+        gwf,
+        save_flows=True,
+        iconvert=0,
+        ss=1.0e-5,
+        sy=0.1,
+        steady_state={0: False},
+        transient={0: True},
+        filename=f"{name}.sto",
+    )
+
+    # MAW
+    well = well3(name)
+    maw = flopy.mf6.ModflowGwfmaw(
+        gwf,
+        filename=f"{name}.maw",
+        print_input=True,
+        print_head=True,
+        print_flows=True,
+        save_flows=True,
+        observations=well.observations,
+        packagedata=well.packagedata,
+        connectiondata=well.connectiondata,
+        perioddata=well.perioddata,
+    )
+
+    # output control
+    oc = flopy.mf6.ModflowGwfoc(
+        gwf,
+        budget_filerecord=f"{name}.cbc",
+        head_filerecord=f"{name}.hds",
+        headprintrecord=[
+            ("COLUMNS", ncol, "WIDTH", 15, "DIGITS", 6, "GENERAL")
+        ],
+        saverecord=[("HEAD", "ALL")],
+        printrecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
+        filename=f"{name}.oc",
+    )
+
+    # head observations
+    obs_data0 = [("head_well_cell", "HEAD", (0, 0, 0))]
+    obs_recarray = {f"{name}.obs.csv": obs_data0}
+    obs = flopy.mf6.ModflowUtlobs(
+        gwf,
+        pname="head_obs",
+        filename=f"{name}.obs",
+        digits=15,
+        print_input=True,
+        continuous=obs_recarray,
+    )
+
+    return sim
+
+
+def eval_results(name, workspace):
+    # MODFLOW 6 maw results
+    test_name = name
+    fpth = os.path.join(workspace, f"{test_name}.maw.obs.csv")
+    tc = np.genfromtxt(fpth, names=True, delimiter=",")
+
+    if test_name.endswith("a"):
+        # M1RATE should be 2000.
+        msg = "The injection rate should be 2000. for all times"
+        assert tc["M1RATE"].min() == tc["M1RATE"].max() == 2000, msg
+
+    elif test_name.endswith("b"):
+        # M1RATE should have a minimum value less than 200 and
+        # M1HEAD should not exceed 0.400001
+        msg = (
+            "Injection rate should fall below 200 and the head should not"
+            "exceed 0.4"
+        )
+        assert tc["M1RATE"].min() < 200.0, msg
+        assert tc["M1HEAD"].max() < 0.400001, msg
+
+    elif test_name.endswith("c"):
+        # M1RATE should have a minimum value less than 800
+        # M1HEAD should not exceed 1.0.
+        msg = (
+            "Min injection rate should be less than 800 and well "
+            "head should not exceed 1.0"
+        )
+        assert tc["M1RATE"].min() < 800.0 and tc["M1HEAD"].max() < 1.0, msg
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    ws = str(function_tmpdir)
+    sim = build_model(idx, ws, targets["mf6"])
+    sim.write_simulation()
+    sim.run_simulation()
+    eval_results(name, ws)
diff --git a/autotest/test_gwf_maw04.py b/autotest/test_gwf_maw04.py
index e77656f0c68..dbbe44cc4c4 100644
--- a/autotest/test_gwf_maw04.py
+++ b/autotest/test_gwf_maw04.py
@@ -3,8 +3,7 @@
 
 import flopy
 import numpy as np
-from modflow_devtools.case import Case
-from pytest_cases import parametrize
+import pytest
 
 # temporal discretization
 nper = 2
@@ -101,198 +100,172 @@ def well4(label):
     )
 
 
-case = Case(
-    name="maw_iss305",
-    nlay=nlay,
-    nrow=nrow,
-    ncol=ncol,
-    nper=nper,
-    delr=delr,
-    perlen=perlen,
-    nstp=nstp,
-    tsmult=tsmult,
-    steady=steady,
-    strt=0,
-    hk=10,
-    nouter=100,
-    ninner=100,
-    hclose=1e-9,
-    rclose=1e-6,
-    relax=1,
-    top=top,
-    botm=botm,
-    confined=confined,
-    ss=ss,
-    chd_spd=chd_spd,
-    chd5_spd=chd5_spd,
-    nhalf=nhalf,
-    radius=radius,
-    wellq=wellq,
-    compare=False,
-)
-cases = [case.copy_update(name=case.name + "a", well=well4("a"),)] + [
-    case.copy_update(name=case.name + label, well=well4(label), xfail=True)
-    for label in [
-        "b",
-        # "c",  # todo: this one passes when it should fail
-        "d",
-        "e",
-        "f",
-    ]
-]
+# npf data
+strt = 0
+hk = 10
 
+# solver
+nouter = 100
+ninner = 100
+hclose = 1e-9
+rclose = 1e-6
+relax = 1
 
-class GwfMaw04Cases:
-    @parametrize(data=cases, ids=[c.name for c in cases])
-    def case_4(self, function_tmpdir, targets, data):
-        name = data.name
-        ws = str(function_tmpdir)
+# subproblems
+subprobs = ["a", "b", "c", "d", "e", "f"]
+ex = [f"maw_iss305{sp}" for sp in subprobs]
+wells = [well4(sp) for sp in subprobs]
+xfail = [False, True, True, True, True, True]
 
-        # build MODFLOW 6 files
-        sim = flopy.mf6.MFSimulation(
-            sim_name=name, version="mf6", exe_name=targets["mf6"], sim_ws=ws
-        )
-        # create tdis package
-        tdis_rc = []
-        for idx in range(data.nper):
-            tdis_rc.append(
-                (data.perlen[idx], data.nstp[idx], data.tsmult[idx])
-            )
-        tdis = flopy.mf6.ModflowTdis(
-            sim, time_units="DAYS", nper=data.nper, perioddata=tdis_rc
-        )
 
-        # create iterative model solution
-        ims = flopy.mf6.ModflowIms(
-            sim,
-            inner_dvclose=data.hclose,
-            rcloserecord=data.rclose,
-            outer_dvclose=data.hclose,
-        )
+def build_model(idx, ws, mf6):
+    name = ex[idx]
+    well = wells[idx]
+    # build MODFLOW 6 files
+    sim = flopy.mf6.MFSimulation(
+        sim_name=name, version="mf6", exe_name=mf6, sim_ws=ws
+    )
+    # create tdis package
+    tdis_rc = []
+    for kper in range(nper):
+        tdis_rc.append((perlen[kper], nstp[kper], tsmult[kper]))
+    tdis = flopy.mf6.ModflowTdis(
+        sim, time_units="DAYS", nper=nper, perioddata=tdis_rc
+    )
 
-        # create gwf model
-        gwf = flopy.mf6.ModflowGwf(sim, modelname=name, save_flows=True)
+    # create iterative model solution
+    ims = flopy.mf6.ModflowIms(
+        sim,
+        inner_dvclose=hclose,
+        rcloserecord=rclose,
+        outer_dvclose=hclose,
+    )
 
-        # discretization
-        dis = flopy.mf6.ModflowGwfdis(
-            gwf,
-            nlay=data.nlay,
-            nrow=data.nrow,
-            ncol=data.ncol,
-            delr=data.delr,
-            delc=data.delr,
-            top=data.top,
-            botm=data.botm,
-        )
-        # initial conditions
-        ic = flopy.mf6.ModflowGwfic(gwf, strt=data.strt)
+    # create gwf model
+    gwf = flopy.mf6.ModflowGwf(sim, modelname=name, save_flows=True)
 
-        # node property flow
-        npf = flopy.mf6.ModflowGwfnpf(
-            gwf, save_flows=False, icelltype=data.confined, k=data.hk
-        )
-        # storage
-        sto = flopy.mf6.ModflowGwfsto(
-            gwf,
-            save_flows=False,
-            iconvert=data.confined,
-            ss=data.ss,
-            steady_state={0: True},
-            transient={1: True},
+    # discretization
+    dis = flopy.mf6.ModflowGwfdis(
+        gwf,
+        nlay=nlay,
+        nrow=nrow,
+        ncol=ncol,
+        delr=delr,
+        delc=delr,
+        top=top,
+        botm=botm,
+    )
+    # initial conditions
+    ic = flopy.mf6.ModflowGwfic(gwf, strt=strt)
+
+    # node property flow
+    npf = flopy.mf6.ModflowGwfnpf(
+        gwf, save_flows=False, icelltype=confined, k=hk
+    )
+    # storage
+    sto = flopy.mf6.ModflowGwfsto(
+        gwf,
+        save_flows=False,
+        iconvert=confined,
+        ss=ss,
+        steady_state={0: True},
+        transient={1: True},
+    )
+    # constant head
+    chd = flopy.mf6.ModflowGwfchd(
+        gwf, stress_period_data=chd_spd, save_flows=False
+    )
+    # multi-aquifer well
+    maw = flopy.mf6.ModflowGwfmaw(
+        gwf,
+        print_input=well.print_input,
+        no_well_storage=well.no_well_storage,
+        packagedata=well.packagedata,
+        connectiondata=well.connectiondata,
+        perioddata=well.perioddata,
+    )
+    # output control
+    oc = flopy.mf6.ModflowGwfoc(
+        gwf,
+        budget_filerecord=f"{name}.cbc",
+        head_filerecord=f"{name}.hds",
+        saverecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
+    )
+    # build MODFLOW-2005 files
+    if xfail[idx]:
+        mc = None
+    else:
+        cmppth = "mf2005"
+        ws = os.path.join(ws, cmppth)
+        mc = flopy.modflow.Modflow(name, model_ws=ws, version=cmppth)
+        dis = flopy.modflow.ModflowDis(
+            mc,
+            nlay=nlay,
+            nrow=nrow,
+            ncol=ncol,
+            nper=nper,
+            perlen=perlen,
+            nstp=nstp,
+            tsmult=tsmult,
+            steady=steady,
+            delr=delr,
+            delc=delr,
+            top=top,
+            botm=botm,
         )
-        # constant head
-        chd = flopy.mf6.ModflowGwfchd(
-            gwf, stress_period_data=data.chd_spd, save_flows=False
+        bas = flopy.modflow.ModflowBas(mc, strt=strt)
+        lpf = flopy.modflow.ModflowLpf(
+            mc,
+            laytyp=confined,
+            hk=hk,
+            vka=hk,
+            ss=ss,
+            sy=0,
         )
-        # multi-aquifer well
-        maw = flopy.mf6.ModflowGwfmaw(
-            gwf,
-            print_input=data.well.print_input,
-            no_well_storage=data.well.no_well_storage,
-            packagedata=data.well.packagedata,
-            connectiondata=data.well.connectiondata,
-            perioddata=data.well.perioddata,
+        chd = flopy.modflow.ModflowChd(mc, stress_period_data=chd5_spd)
+        # mnw2
+        # empty mnw2 file to create recarrays
+        mnw2 = flopy.modflow.ModflowMnw2(mc)
+        node_data = mnw2.get_empty_node_data(2)
+        node_data["ztop"] = np.array([top, botm[0]])
+        node_data["zbotm"] = np.array([botm[0], botm[1]])
+        node_data["i"] = np.array([nhalf, nhalf])
+        node_data["j"] = np.array([nhalf, nhalf])
+        node_data["wellid"] = np.array(["well1", "well1"])
+        node_data["losstype"] = np.array(["skin", "skin"])
+        node_data["rw"] = np.array([radius, radius])
+        node_data["rskin"] = np.array([sradius[name[-1]], sradius[name[-1]]])
+        hks = hk * skin_mult[name[-1]]
+        node_data["kskin"] = np.array([hks, hks])
+        dtype = [("wellid", np.unicode_, 20), ("qdes", "<f8")]
+        spd0 = np.zeros(1, dtype=dtype)
+        spd0["wellid"] = "well1"
+        spd1 = np.zeros(1, dtype=dtype)
+        spd1["wellid"] = "well1"
+        spd1["qdes"] = wellq
+        spd = {0: spd0, 1: spd1}
+        mnw2 = flopy.modflow.ModflowMnw2(
+            mc,
+            mnwmax=1,
+            node_data=node_data,
+            stress_period_data=spd,
+            itmp=[1, 1],
+            mnwprnt=2,
         )
-        # output control
-        oc = flopy.mf6.ModflowGwfoc(
-            gwf,
-            budget_filerecord=f"{name}.cbc",
-            head_filerecord=f"{name}.hds",
-            saverecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
+        oc = flopy.modflow.ModflowOc(
+            mc,
+            stress_period_data=None,
+            save_every=1,
+            save_types=["save head", "save budget"],
         )
-        # build MODFLOW-2005 files
-        if data.xfail:
-            mc = None
-        else:
-            cmppth = "mf2005"
-            ws = os.path.join(str(function_tmpdir), cmppth)
-            mc = flopy.modflow.Modflow(name, model_ws=ws, version=cmppth)
-            dis = flopy.modflow.ModflowDis(
-                mc,
-                nlay=data.nlay,
-                nrow=data.nrow,
-                ncol=data.ncol,
-                nper=data.nper,
-                perlen=data.perlen,
-                nstp=data.nstp,
-                tsmult=data.tsmult,
-                steady=data.steady,
-                delr=data.delr,
-                delc=data.delr,
-                top=data.top,
-                botm=data.botm,
-            )
-            bas = flopy.modflow.ModflowBas(mc, strt=data.strt)
-            lpf = flopy.modflow.ModflowLpf(
-                mc,
-                laytyp=data.confined,
-                hk=data.hk,
-                vka=data.hk,
-                ss=data.ss,
-                sy=0,
-            )
-            chd = flopy.modflow.ModflowChd(
-                mc, stress_period_data=data.chd5_spd
-            )
-            # mnw2
-            # empty mnw2 file to create recarrays
-            mnw2 = flopy.modflow.ModflowMnw2(mc)
-            node_data = mnw2.get_empty_node_data(2)
-            node_data["ztop"] = np.array([data.top, data.botm[0]])
-            node_data["zbotm"] = np.array([data.botm[0], data.botm[1]])
-            node_data["i"] = np.array([data.nhalf, data.nhalf])
-            node_data["j"] = np.array([data.nhalf, data.nhalf])
-            node_data["wellid"] = np.array(["well1", "well1"])
-            node_data["losstype"] = np.array(["skin", "skin"])
-            node_data["rw"] = np.array([data.radius, data.radius])
-            node_data["rskin"] = np.array(
-                [sradius[name[-1]], sradius[name[-1]]]
-            )
-            hks = hk * skin_mult[name[-1]]
-            node_data["kskin"] = np.array([hks, hks])
-            dtype = [("wellid", np.unicode_, 20), ("qdes", "<f8")]
-            spd0 = np.zeros(1, dtype=dtype)
-            spd0["wellid"] = "well1"
-            spd1 = np.zeros(1, dtype=dtype)
-            spd1["wellid"] = "well1"
-            spd1["qdes"] = data.wellq
-            spd = {0: spd0, 1: spd1}
-            mnw2 = flopy.modflow.ModflowMnw2(
-                mc,
-                mnwmax=1,
-                node_data=node_data,
-                stress_period_data=spd,
-                itmp=[1, 1],
-                mnwprnt=2,
-            )
-            oc = flopy.modflow.ModflowOc(
-                mc,
-                stress_period_data=None,
-                save_every=1,
-                save_types=["save head", "save budget"],
-            )
-            pcg = flopy.modflow.ModflowPcg(
-                mc, hclose=data.hclose, rclose=data.rclose
-            )
+        pcg = flopy.modflow.ModflowPcg(mc, hclose=hclose, rclose=rclose)
+
+    return sim, mc
+
 
-        return data, sim, None, None
+@pytest.mark.parametrize("idx, name", list(enumerate(ex)))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    ws = str(function_tmpdir)
+    sim, _ = build_model(idx, ws, targets["mf6"])
+    sim.write_simulation()
+    sim.run_simulation()
diff --git a/autotest/test_gwf_maw05.py b/autotest/test_gwf_maw05.py
index bad9a0c1033..a7de2550a66 100644
--- a/autotest/test_gwf_maw05.py
+++ b/autotest/test_gwf_maw05.py
@@ -1,21 +1,23 @@
-# Test maw package ability to equalize.
-# maw_05a - well and aquifer start at 4; should be now flow
-# maw_05b - well starts at 3.5 and aquifer starts at 4; should equalize
-# maw_05c - well starts at or below 3.0; not working yet
+"""
+Test maw package ability to equalize.
+maw_05a - well and aquifer start at 4; should be now flow
+maw_05b - well starts at 3.5 and aquifer starts at 4; should equalize
+maw_05c - well starts at or below 3.0; not working yet
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["maw_05a", "maw_05b", "maw_05c"]
+cases = ["maw_05a", "maw_05b", "maw_05c"]
 mawstrt = [4.0, 3.5, 2.5]  # add 3.0
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     lx = 7.0
     lz = 4.0
     nlay = 4
@@ -42,10 +44,10 @@ def build_model(idx, dir):
     nouter, ninner = 700, 10
     hclose, rclose, relax = 1e-8, 1e-6, 0.97
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -112,16 +114,16 @@ def build_model(idx, dir):
     mstrt = mawstrt[idx]
     mawcondeqn = "THIEM"
     mawngwfnodes = nlay
-    # <wellno> <radius> <bottom> <strt> <condeqn> <ngwfnodes>
+    # <ifno> <radius> <bottom> <strt> <condeqn> <ngwfnodes>
     mawpackagedata = [
         [0, mawradius, mawbottom, mstrt, mawcondeqn, mawngwfnodes]
     ]
-    # <wellno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
+    # <ifno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
     mawconnectiondata = [
         [0, icon, (icon, 0, 0), top, mawbottom, -999.0, -999.0]
         for icon in range(nlay)
     ]
-    # <wellno> <mawsetting>
+    # <ifno> <mawsetting>
     mawperioddata = [[0, "STATUS", "ACTIVE"]]
     maw = flopy.mf6.ModflowGwfmaw(
         gwf,
@@ -177,26 +179,24 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # calculate volume of water and make sure it is conserved
-    name = ex[sim.idxsim]
+    name = cases[idx]
     gwfname = "gwf_" + name
     fname = gwfname + ".maw.bin"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     bobj = flopy.utils.HeadFile(fname, text="HEAD")
     stage = bobj.get_alldata().flatten()
 
     fname = gwfname + ".hds"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     hobj = flopy.utils.HeadFile(fname)
     head = hobj.get_alldata()
 
     # calculate initial volume of water in well and aquifer
-    v0maw = mawstrt[sim.idxsim] * np.pi * 0.1**2
+    v0maw = mawstrt[idx] * np.pi * 0.1**2
     v0gwf = 4 * 7 * 0.3
     v0 = v0maw + v0gwf
     top = [4.0, 3.0, 2.0, 1.0]
@@ -214,7 +214,6 @@ def eval_results(sim):
     # calculate current volume of water in well and aquifer and compare with
     # initial volume
     for kstp, mawstage in enumerate(stage):
-
         vgwf = 0
         for k in range(nlay):
             for j in range(ncol):
@@ -241,17 +240,14 @@ def eval_results(sim):
     )
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare="mf6_regression",
     )
+    test.run()
diff --git a/autotest/test_gwf_maw06.py b/autotest/test_gwf_maw06.py
index 7a4748b059c..d16b04135b2 100644
--- a/autotest/test_gwf_maw06.py
+++ b/autotest/test_gwf_maw06.py
@@ -1,16 +1,18 @@
-# Test maw package ability to equalize and the flow correction.
-# maw_06a - well start at .25, aquifer starts at 2
-# maw_06b - well starts at 2, aquifer starts at .25
+"""
+Test maw package ability to equalize the flow correction.
+maw_06a - well start at .25, aquifer starts at 2
+maw_06b - well starts at 2, aquifer starts at .25
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["maw_06a", "maw_06b"]
+cases = ["maw_06a", "maw_06b"]
 
 nlay = 2
 nrow = 1
@@ -47,7 +49,7 @@
 mawcond = Kh * delc * dz / (0.5 * delr)
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nper = 1
     perlen = [10.0]
     nstp = [100]
@@ -60,10 +62,10 @@ def build_model(idx, dir):
     nouter, ninner = 700, 200
     hclose, rclose, relax = 1e-9, 1e-9, 1.0
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name,
         version="mf6",
@@ -131,14 +133,14 @@ def build_model(idx, dir):
     mstrt = mawstrt[idx]
     mawcondeqn = "SPECIFIED"
     mawngwfnodes = nlay
-    # <wellno> <radius> <bottom> <strt> <condeqn> <ngwfnodes>
+    # <ifno> <radius> <bottom> <strt> <condeqn> <ngwfnodes>
     mawpackagedata = [[0, mawradius, bot, mstrt, mawcondeqn, mawngwfnodes]]
-    # <wellno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
+    # <ifno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
     mawconnectiondata = [
         [0, icon, (icon, 0, 0), top, bot, mawcond, -999]
         for icon in range(nlay)
     ]
-    # <wellno> <mawsetting>
+    # <ifno> <mawsetting>
     mawperioddata = [[0, "STATUS", "ACTIVE"]]
     mbin = f"{gwfname}.maw.bin"
     mbud = f"{gwfname}.maw.bud"
@@ -197,27 +199,25 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # calculate volume of water and make sure it is conserved
-    name = ex[sim.idxsim]
+    name = cases[idx]
     gwfname = "gwf_" + name
     fname = gwfname + ".maw.bin"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     bobj = flopy.utils.HeadFile(fname, text="HEAD")
     stage = bobj.get_alldata().flatten()
 
     fname = gwfname + ".hds"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     hobj = flopy.utils.HeadFile(fname)
     head = hobj.get_alldata()
 
     # calculate initial volume of water in well and aquifer
-    v0maw = mawstrt[sim.idxsim] * mawarea
-    v0gwf = (gwfstrt[sim.idxsim] - bot) * sy * gwfarea
+    v0maw = mawstrt[idx] * mawarea
+    v0gwf = (gwfstrt[idx] - bot) * sy * gwfarea
     v0 = v0maw + v0gwf
 
     print(
@@ -257,13 +257,13 @@ def eval_results(sim):
 
     # compare the maw-gwf flows with the gwf-maw flows
     fname = gwfname + ".maw.bud"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     mbud = flopy.utils.CellBudgetFile(fname, precision="double")
     maw_gwf = mbud.get_data(text="GWF")
 
     fname = gwfname + ".cbc"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     gbud = flopy.utils.CellBudgetFile(fname, precision="double")
     gwf_maw = gbud.get_data(text="MAW")
@@ -279,17 +279,14 @@ def eval_results(sim):
             assert np.allclose(qmaw, -qgwf), msg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare="mf6_regression",
     )
+    test.run()
diff --git a/autotest/test_gwf_maw07.py b/autotest/test_gwf_maw07.py
index c92ff6e105b..8ddede3585e 100644
--- a/autotest/test_gwf_maw07.py
+++ b/autotest/test_gwf_maw07.py
@@ -1,16 +1,18 @@
-# Modifiy the previous test by having a first stress period where the
-# MAW well is inactive.  Test ensures that gwf-maw and maw-gwf flows reported
-# in the gwf and maw budget files are zero for this first period.
+"""
+Modify the previous test by having a first stress period where the
+MAW well is inactive. Test ensures that gwf-maw and maw-gwf flows
+in the gwf and maw budget files are zero for this first period.
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["maw_07a", "maw_07b"]
+cases = ["maw_07a", "maw_07b"]
 
 nlay = 2
 nrow = 1
@@ -47,7 +49,7 @@
 mawcond = Kh * delc * dz / (0.5 * delr)
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nper = 2
     perlen = [10.0, 10.0]
     nstp = [1, 100]
@@ -60,10 +62,10 @@ def build_model(idx, dir):
     nouter, ninner = 700, 200
     hclose, rclose, relax = 1e-9, 1e-9, 1.0
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name,
         version="mf6",
@@ -131,14 +133,14 @@ def build_model(idx, dir):
     mstrt = mawstrt[idx]
     mawcondeqn = "SPECIFIED"
     mawngwfnodes = nlay
-    # <wellno> <radius> <bottom> <strt> <condeqn> <ngwfnodes>
+    # <ifno> <radius> <bottom> <strt> <condeqn> <ngwfnodes>
     mawpackagedata = [[0, mawradius, bot, mstrt, mawcondeqn, mawngwfnodes]]
-    # <wellno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
+    # <ifno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
     mawconnectiondata = [
         [0, icon, (icon, 0, 0), top, bot, mawcond, -999]
         for icon in range(nlay)
     ]
-    # <wellno> <mawsetting>
+    # <ifno> <mawsetting>
     mawperioddata = {}
     mawperioddata[0] = [[0, "STATUS", "INACTIVE"]]
     mawperioddata[1] = [[0, "STATUS", "ACTIVE"]]
@@ -199,27 +201,25 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # calculate volume of water and make sure it is conserved
-    name = ex[sim.idxsim]
+    name = cases[idx]
     gwfname = "gwf_" + name
     fname = gwfname + ".maw.bin"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     bobj = flopy.utils.HeadFile(fname, text="HEAD")
     stage = bobj.get_alldata().flatten()[1:]
 
     fname = gwfname + ".hds"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     hobj = flopy.utils.HeadFile(fname)
     head = hobj.get_alldata()[1:]
 
     # calculate initial volume of water in well and aquifer
-    v0maw = mawstrt[sim.idxsim] * mawarea
-    v0gwf = (gwfstrt[sim.idxsim] - bot) * sy * gwfarea
+    v0maw = mawstrt[idx] * mawarea
+    v0gwf = (gwfstrt[idx] - bot) * sy * gwfarea
     v0 = v0maw + v0gwf
 
     print(
@@ -259,13 +259,13 @@ def eval_results(sim):
 
     # compare the maw-gwf flows with the gwf-maw flows
     fname = gwfname + ".maw.bud"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     mbud = flopy.utils.CellBudgetFile(fname, precision="double")
     maw_gwf = mbud.get_data(text="GWF")
 
     fname = gwfname + ".cbc"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     gbud = flopy.utils.CellBudgetFile(fname, precision="double")
     gwf_maw = gbud.get_data(text="MAW")
@@ -285,17 +285,14 @@ def eval_results(sim):
             assert np.allclose(qmaw, -qgwf), msg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare="mf6_regression",
     )
+    test.run()
diff --git a/autotest/test_gwf_maw08.py b/autotest/test_gwf_maw08.py
index e4f423298f9..94e7dfa36f7 100644
--- a/autotest/test_gwf_maw08.py
+++ b/autotest/test_gwf_maw08.py
@@ -1,15 +1,17 @@
-# test to evaluate Newton-Raphson solution for a single column steady-state
-# dry multi-aquifer well problem. Developed to address issue #546
+"""
+Test Newton-Raphson solution for a single column steady-state
+dry multi-aquifer well problem. Developed to address issue #546
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ("maw_08a", "maw_08b")
+cases = ("maw_08a", "maw_08b")
 dis_option = ("dis", "disv")
 
 nlay = 3
@@ -42,13 +44,13 @@
 radius = 0.05
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     dvclose, rclose, relax = 1e-9, 1e-9, 1.0
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name,
         version="mf6",
@@ -121,7 +123,7 @@ def build_model(idx, dir):
         k33=Kv,
     )
 
-    # <wellno> <radius> <bottom> <strt> <condeqn> <ngwfnodes>
+    # <ifno> <radius> <bottom> <strt> <condeqn> <ngwfnodes>
     mawpackagedata = flopy.mf6.ModflowGwfmaw.packagedata.empty(gwf, maxbound=1)
     mawpackagedata["radius"] = radius
     mawpackagedata["bottom"] = maw_bot
@@ -129,7 +131,7 @@ def build_model(idx, dir):
     mawpackagedata["condeqn"] = "thiem"
     mawpackagedata["ngwfnodes"] = 2
 
-    # <wellno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
+    # <ifno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
     mawconnectiondata = flopy.mf6.ModflowGwfmaw.connectiondata.empty(
         gwf, maxbound=2
     )
@@ -194,14 +196,12 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def eval_results(idx, test):
     # calculate volume of water and make sure it is conserved
-    name = ex[sim.idxsim]
+    name = cases[idx]
     gwfname = "gwf_" + name
     fname = gwfname + ".maw.bin"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     bobj = flopy.utils.HeadFile(fname, text="HEAD")
 
@@ -211,20 +211,20 @@ def eval_results(sim):
     ), f"simulated maw head ({well_head[0]}) does not equal 10."
 
     fname = gwfname + ".hds"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     hobj = flopy.utils.HeadFile(fname)
     head = hobj.get_alldata()[1:]
 
     # compare the maw-gwf flows with the gwf-maw flows
     fname = gwfname + ".maw.bud"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     mbud = flopy.utils.CellBudgetFile(fname, precision="double")
     maw_gwf = mbud.get_data(text="GWF")
 
     fname = gwfname + ".cbc"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     gbud = flopy.utils.CellBudgetFile(fname, precision="double")
     gwf_maw = gbud.get_data(text="MAW")
@@ -240,17 +240,13 @@ def eval_results(sim):
             assert np.allclose(qmaw, -qgwf), msg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: eval_results(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_maw09.py b/autotest/test_gwf_maw09.py
index 48541261bb7..730e5cb0c8d 100644
--- a/autotest/test_gwf_maw09.py
+++ b/autotest/test_gwf_maw09.py
@@ -1,15 +1,17 @@
-# test to evaluate Newton-Raphson solution for a single column transient
-# dry multi-aquifer well problem. Developed to address issue #546
+"""
+test to evaluate Newton-Raphson solution for a single column transient
+dry multi-aquifer well problem. Developed to address issue #546
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ("maw_09a", "maw_09b", "maw_09c", "maw_09d")
+cases = ("maw_09a", "maw_09b", "maw_09c", "maw_09d")
 dis_option = ("dis", "dis", "disv", "disv")
 flow_correction = (None, True, None, True)
 
@@ -44,13 +46,13 @@
 radius = np.sqrt(1.0 / np.pi)
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     dvclose, rclose, relax = 1e-9, 1e-9, 1.0
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name,
         version="mf6",
@@ -146,7 +148,7 @@ def build_model(idx, dir):
         gwf, ss=0.0, sy=1.0, transient=True, iconvert=1
     )
 
-    # <wellno> <radius> <bottom> <strt> <condeqn> <ngwfnodes>
+    # <ifno> <radius> <bottom> <strt> <condeqn> <ngwfnodes>
     mawpackagedata = flopy.mf6.ModflowGwfmaw.packagedata.empty(gwf, maxbound=1)
     mawpackagedata["radius"] = radius
     mawpackagedata["bottom"] = maw_bot
@@ -154,7 +156,7 @@ def build_model(idx, dir):
     mawpackagedata["condeqn"] = "specified"
     mawpackagedata["ngwfnodes"] = 2
 
-    # <wellno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
+    # <ifno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
     mawconnectiondata = flopy.mf6.ModflowGwfmaw.connectiondata.empty(
         gwf, maxbound=2
     )
@@ -220,21 +222,19 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwfname = "gwf_" + name
 
     # get well observations
     fname = f"{gwfname}.gwf.obs.csv"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     gobs = np.genfromtxt(fname, delimiter=",", names=True)
 
     # get well observations
     fname = f"{gwfname}.maw.obs.csv"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     wobs = np.genfromtxt(fname, delimiter=",", names=True)["WHEAD"]
 
@@ -242,10 +242,10 @@ def eval_results(sim):
     # volume comparisons can be made based on saturated thickness because
     # the cell area and well area are both equal to 1
     v0 = (maw_strt - 10.0) + (strt - 0.0)
-    for idx, w in enumerate(wobs):
+    for i, w in enumerate(wobs):
         vg = 0.0
         for jdx, tag in enumerate(("C1", "C2", "C3")):
-            g = gobs[tag][idx]
+            g = gobs[tag][i]
             ctop = zelevs[jdx]
             cbot = zelevs[jdx + 1]
             if g > ctop:
@@ -259,7 +259,7 @@ def eval_results(sim):
         vt = vw + vg
 
         # write a message
-        msg = f"{idx}\n  well volume: {vw} "
+        msg = f"{i}\n  well volume: {vw} "
         msg += f"\n  groundwater volume: {vg}"
         msg += f"\n  total volume: {vt}"
         print(msg)
@@ -276,20 +276,20 @@ def eval_results(sim):
     ), f"final simulated maw head ({well_head}) does not equal 17.25."
 
     fname = gwfname + ".hds"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     hobj = flopy.utils.HeadFile(fname)
     head = hobj.get_alldata()[1:]
 
     # compare the maw-gwf flows with the gwf-maw flows
     fname = gwfname + ".maw.bud"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     mbud = flopy.utils.CellBudgetFile(fname, precision="double")
     maw_gwf = mbud.get_data(text="GWF")
 
     fname = gwfname + ".cbc"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     gbud = flopy.utils.CellBudgetFile(fname, precision="double")
     gwf_maw = gbud.get_data(text="MAW")
@@ -305,17 +305,14 @@ def eval_results(sim):
             assert np.allclose(qmaw, -qgwf), msg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
+        compare="mf6_regression",
     )
+    test.run()
diff --git a/autotest/test_gwf_maw10.py b/autotest/test_gwf_maw10.py
index f677c7814c7..0ef9d13338e 100644
--- a/autotest/test_gwf_maw10.py
+++ b/autotest/test_gwf_maw10.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 Test to confirm that the sum of rate-actual and maw-reduction observations
 is equal to the specified MAW extraction or injection pumping rate when
 reported using the MAW_FLOW_REDUCE_CSV option. Injection and extraction
@@ -12,10 +11,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["maw10a", "maw10b", "maw10c", "maw10d"]
+cases = ["maw10a", "maw10b", "maw10c", "maw10d"]
 mawsetting_a = {
     0: [
         [0, "rate", -2000.0],
@@ -61,8 +60,7 @@
 mawsettings = [mawsetting_a, mawsetting_b, mawsetting_c, mawsetting_d]
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 101, 101
     nper = 2
     perlen = [500.0, 500.0]
@@ -81,10 +79,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(sim_name=name, sim_ws=ws)
 
     # create tdis package
@@ -212,14 +210,11 @@ def build_model(idx, dir):
 # 1. within the .maw-reduction.csv file, do values of actual + reduction = requested?
 # 2. do the values in .maw-reduction.csv file match with the .maw.obs.csv file at each time
 #  (and all are reduction times present in the obs file)?
-def eval_mawred(sim):
-    print("evaluating MAW flow reduction outputs...")
-
+def check_output(idx, test):
     # MODFLOW 6 maw results
-    idx = sim.idxsim
-    name = ex[idx]
-    fpthobs = os.path.join(sim.simpath, f"{name}.maw.obs.csv")
-    fpthmfr = os.path.join(sim.simpath, f"{name}.maw-reduction.csv")
+    name = cases[idx]
+    fpthobs = os.path.join(test.workspace, f"{name}.maw.obs.csv")
+    fpthmfr = os.path.join(test.workspace, f"{name}.maw-reduction.csv")
     try:
         tcobs = np.genfromtxt(fpthobs, names=True, delimiter=",")
     except:
@@ -266,17 +261,13 @@ def eval_mawred(sim):
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_mawred, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_maw_cases.py b/autotest/test_gwf_maw_cases.py
deleted file mode 100644
index 4469bcee2cc..00000000000
--- a/autotest/test_gwf_maw_cases.py
+++ /dev/null
@@ -1,817 +0,0 @@
-import os
-from collections import namedtuple
-from types import SimpleNamespace
-
-import flopy
-import numpy as np
-from modflow_devtools.case import Case
-from pytest_cases import parametrize
-
-well1 = SimpleNamespace(
-    observations={"maw_obs.csv": [("mh1", "head", 1)]},
-    packagedata=[[0, 0.1, 50.0, 100.0, "THIEM", 1]],
-    connectiondata=[[0, 0, (0, 0, 1), 100.0, 50.0, 1.0, 0.1]],
-    perioddata=[[0, "rate", 0.0]],
-)
-
-well2 = SimpleNamespace(
-    observations={"maw_obs.csv": [("mh1", "head", 1)]},
-    packagedata=[
-        [0, 0.1, 0.0, 100.0, "THIEM", 1],
-        [1, 0.1, 0.0, 100.0, "THIEM", 1],
-    ],
-    connectiondata=[
-        [0, 0, (0, 0, 1), 100.0, 0.0, 1.0, 0.1],
-        [1, 0, (0, 0, 1), 100.0, 0.0, 1.0, 0.1],
-    ],
-    perioddata={
-        0: [
-            [0, "rate", -20.0],
-            [0, "status", "inactive"],
-            [0, "rate_scaling", 1.0, 15.0],
-            [1, "rate", -30.0],
-            [1, "status", "inactive"],
-            [1, "rate_scaling", 5.0, 15.0],
-        ],
-        1: [
-            [0, "rate", -110.0],
-            [0, "status", "active"],
-            [1, "rate", -130.0],
-            [1, "status", "active"],
-        ],
-        3: [[0, "status", "inactive"]],
-        4: [[0, "status", "active"]],
-    },
-)
-
-
-def well3(name):
-    perioddata = {
-        "maw03a": [
-            (0, "rate", 2000.0),
-        ],
-        "maw03b": [(0, "rate", 2000.0), (0, "head_limit", 0.4)],
-        "maw03c": [(0, "rate", 2000.0), (0, "rate_scaling", 0.0, 1.0)],
-    }
-    wellbottom = -1000
-    return SimpleNamespace(
-        observations={
-            f"{name}.maw.obs.csv": [
-                ("m1head", "head", (0,)),
-                ("m1rate", "rate", (0,)),
-            ]  # is this index one-based? Not if in a tuple
-        },
-        packagedata=[[0, 0.15, wellbottom, 0.0, "THIEM", 1]],
-        connectiondata=[[0, 0, (0, 50, 50), 0.0, wellbottom, 0.0, 0.0]],
-        perioddata=perioddata[name],
-    )
-
-
-def well4(case, condeqn):
-    radius0 = np.sqrt(
-        case.delr[case.nhalf] * case.delr[case.nhalf] / (8.0 * np.pi)
-    )
-    radius = 0.25
-    sradius0 = radius + 0.1
-    sradius = [sradius0, sradius0, sradius0, sradius0, sradius0, radius0 * 1.5]
-    packagedata = [[0, case.radius, case.botm[-1], case.strt, condeqn, 2]]
-    connectiondata = [
-        [
-            0,
-            0,
-            (0, case.nhalf, case.nhalf),
-            case.top,
-            case.botm[0],
-            case.hks,
-            sradius[case.name],
-        ],
-        [
-            0,
-            1,
-            (1, case.nhalf, case.nhalf),
-            case.botm[0],
-            case.botm[1],
-            case.hks,
-            sradius[case.name],
-        ],
-    ]
-    perioddata = {1: [[0, "RATE", case.wellq]]}
-    return SimpleNamespace(
-        print_input=True,
-        no_well_storage=True,
-        packagedata=packagedata,
-        connectiondata=connectiondata,
-        perioddata=perioddata,
-    )
-
-
-class GwfMawCases:
-    """
-    Test cases for multi-aquifer well groundwater flow models.
-    """
-
-    budtol = 1e-2
-    bud_lst = ["GWF_IN", "GWF_OUT", "RATE_IN", "RATE_OUT"]
-
-    case1 = Case(
-        name="maw01",
-        nlay=1,
-        nrow=1,
-        ncol=3,
-        nper=3,
-        delr=300,
-        delc=300,
-        krylov="CG",
-        perlen=3 * [1],
-        nstp=3 * [1],
-        tsmult=3 * [1],
-        well=well1,
-        strt=100,
-        hk=1,
-        nouter=100,
-        ninner=300,
-        hclose=1e-9,
-        rclose=1e-3,
-        relaxation_factor=1,
-        newton=None,
-        compare=False,
-    )
-    cases1 = [
-        case1,
-        case1.copy_update(name="maw01nwt", krylov="BICGSTAB", newton="NEWTON"),
-        case1.copy_update(
-            name="maw01nwtur",
-            krylov="BICGSTAB",
-            newton="NEWTON UNDER_RELAXATION",
-        ),
-    ]
-
-    @parametrize(data=cases1, ids=[c.name for c in cases1])
-    def case_1(self, function_tmpdir, targets, data):
-        sim = flopy.mf6.MFSimulation(
-            sim_name=data.name,
-            version="mf6",
-            exe_name=targets["mf6"],
-            sim_ws=str(function_tmpdir),
-        )
-
-        # create tdis package
-        tdis_rc = [
-            (data.perlen[i], data.nstp[i], data.tsmult[i])
-            for i in range(data.nper)
-        ]
-        tdis = flopy.mf6.ModflowTdis(
-            sim, time_units="DAYS", nper=data.nper, perioddata=tdis_rc
-        )
-
-        # create gwf model
-        gwf = flopy.mf6.MFModel(
-            sim,
-            model_type="gwf6",
-            modelname=data.name,
-            model_nam_file=f"{data.name}.nam",
-        )
-        gwf.name_file.newtonoptions = data.newton
-
-        # create iterative model solution and register the gwf model with it
-        ims = flopy.mf6.ModflowIms(
-            sim,
-            print_option="SUMMARY",
-            outer_dvclose=data.hclose,
-            outer_maximum=data.nouter,
-            under_relaxation="NONE",
-            inner_maximum=data.ninner,
-            inner_dvclose=data.hclose,
-            rcloserecord=data.rclose,
-            linear_acceleration=data.krylov,
-            scaling_method="NONE",
-            reordering_method="NONE",
-            relaxation_factor=data.relaxation_factor,
-        )
-        sim.register_ims_package(ims, [gwf.name])
-
-        dis = flopy.mf6.ModflowGwfdis(
-            gwf,
-            nlay=data.nlay,
-            nrow=data.nrow,
-            ncol=data.ncol,
-            delr=data.delr,
-            delc=data.delc,
-            top=100.0,
-            botm=0.0,
-            idomain=1,
-            filename=f"{data.name}.dis",
-        )
-
-        # initial conditions
-        ic = flopy.mf6.ModflowGwfic(
-            gwf, strt=data.strt, filename=f"{data.name}.ic"
-        )
-
-        # node property flow
-        npf = flopy.mf6.ModflowGwfnpf(
-            gwf,
-            save_flows=True,
-            icelltype=1,
-            k=data.hk,
-            k33=data.hk,
-            filename=f"{data.name}.npf",
-        )
-        # storage
-        sto = flopy.mf6.ModflowGwfsto(
-            gwf,
-            save_flows=True,
-            iconvert=1,
-            ss=0.0,
-            sy=0.1,
-            steady_state={0: True},
-            # transient={1: False},
-            filename=f"{data.name}.sto",
-        )
-
-        # chd files
-        chdlist0 = []
-        chdlist0.append([(0, 0, 0), 100.0])
-        chdlist0.append([(0, 0, 2), 100.0])
-
-        chdlist1 = []
-        chdlist1.append([(0, 0, 0), 25.0])
-        chdlist1.append([(0, 0, 2), 25.0])
-
-        chdspdict = {0: chdlist0, 1: chdlist1, 2: chdlist0}
-        chd = flopy.mf6.ModflowGwfchd(
-            gwf,
-            stress_period_data=chdspdict,
-            save_flows=False,
-            filename=f"{data.name}.chd",
-        )
-
-        # wel files
-        # wel = flopy.mf6.ModflowGwfwel(gwf, print_input=True, print_flows=True,
-        #                              maxbound=len(ws),
-        #                              periodrecarray=wd6,
-        #                              save_flows=False)
-        # MAW
-        maw = flopy.mf6.ModflowGwfmaw(
-            gwf,
-            filename=f"{data.name}.maw",
-            print_input=True,
-            print_head=True,
-            print_flows=True,
-            save_flows=True,
-            observations=data.well.observations,
-            packagedata=data.well.packagedata,
-            connectiondata=data.well.connectiondata,
-            perioddata=data.well.perioddata,
-        )
-
-        # output control
-        oc = flopy.mf6.ModflowGwfoc(
-            gwf,
-            budget_filerecord=f"{data.name}.cbc",
-            head_filerecord=f"{data.name}.hds",
-            headprintrecord=[
-                ("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")
-            ],
-            saverecord=[("HEAD", "ALL")],
-            printrecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
-            filename=f"{data.name}.oc",
-        )
-
-        return data, sim, None, self.eval_1
-
-    def eval_1(self, config, data):
-        print("evaluating MAW heads...")
-
-        # MODFLOW 6 maw results
-        fpth = os.path.join(config.simpath, "maw_obs.csv")
-        tc = np.genfromtxt(fpth, names=True, delimiter=",")
-
-        # create known results array
-        tc0 = np.array([100.0, 25.0, 100.0])
-
-        # calculate maximum absolute error
-        diff = tc["MH1"] - tc0
-        diffmax = np.abs(diff).max()
-        dtol = 1e-9
-        msg = f"maximum absolute maw head difference ({diffmax}) "
-
-        if diffmax > dtol:
-            config.success = False
-            msg += f"exceeds {dtol}"
-            assert diffmax < dtol, msg
-        else:
-            config.success = True
-            print("    " + msg)
-
-    case2 = Case(
-        name="maw02",
-        krylov="CG",
-        nlay=1,
-        nrow=1,
-        ncol=3,
-        nper=5,
-        delr=300,
-        delc=300,
-        perlen=5 * [1],
-        nstp=5 * [1],
-        tsmult=5 * [1],
-        well=well2,
-        strt=100,
-        hk=1,
-        nouter=100,
-        ninner=300,
-        hclose=1e-9,
-        rclose=1e-3,
-        relaxation_factor=1,
-        compare=False,
-    )
-    cases2 = [case2]
-
-    @parametrize(data=cases2, ids=[c.name for c in cases2])
-    def case_2(self, function_tmpdir, targets, data):
-        name = data.name
-        ws = str(function_tmpdir)
-        sim = flopy.mf6.MFSimulation(
-            sim_name=name, version="mf6", exe_name=targets["mf6"], sim_ws=ws
-        )
-
-        # create tdis package
-        tdis_rc = [
-            (data.perlen[i], data.nstp[i], data.tsmult[i])
-            for i in range(data.nper)
-        ]
-        tdis = flopy.mf6.ModflowTdis(
-            sim, time_units="DAYS", nper=data.nper, perioddata=tdis_rc
-        )
-
-        # create gwf model
-        gwf = flopy.mf6.MFModel(
-            sim,
-            model_type="gwf6",
-            modelname=name,
-            model_nam_file=f"{name}.nam",
-        )
-
-        # create iterative model solution and register the gwf model with it
-        ims = flopy.mf6.ModflowIms(
-            sim,
-            print_option="SUMMARY",
-            outer_dvclose=data.hclose,
-            outer_maximum=data.nouter,
-            under_relaxation="NONE",
-            inner_maximum=data.ninner,
-            inner_dvclose=data.hclose,
-            rcloserecord=data.rclose,
-            linear_acceleration=data.krylov,
-            scaling_method="NONE",
-            reordering_method="NONE",
-            relaxation_factor=data.relaxation_factor,
-        )
-        sim.register_ims_package(ims, [gwf.name])
-
-        dis = flopy.mf6.ModflowGwfdis(
-            gwf,
-            nlay=data.nlay,
-            nrow=data.nrow,
-            ncol=data.ncol,
-            delr=data.delr,
-            delc=data.delc,
-            top=100.0,
-            botm=0.0,
-            idomain=1,
-            filename=f"{name}.dis",
-        )
-
-        # initial conditions
-        ic = flopy.mf6.ModflowGwfic(gwf, strt=data.strt, filename=f"{name}.ic")
-
-        # node property flow
-        npf = flopy.mf6.ModflowGwfnpf(
-            gwf,
-            save_flows=True,
-            icelltype=1,
-            k=data.hk,
-            k33=data.hk,
-            filename=f"{name}.npf",
-        )
-        # storage
-        sto = flopy.mf6.ModflowGwfsto(
-            gwf,
-            save_flows=True,
-            iconvert=1,
-            ss=0.0,
-            sy=0.1,
-            steady_state={0: True},
-            # transient={1: False},
-            filename=f"{name}.sto",
-        )
-
-        # chd files
-        chdlist0 = []
-        chdlist0.append([(0, 0, 0), 100.0])
-        chdlist0.append([(0, 0, 2), 100.0])
-
-        chdlist1 = []
-        chdlist1.append([(0, 0, 0), 25.0])
-        chdlist1.append([(0, 0, 2), 25.0])
-
-        chdspdict = {0: chdlist0, 1: chdlist1, 2: chdlist0}
-        chd = flopy.mf6.ModflowGwfchd(
-            gwf,
-            stress_period_data=chdspdict,
-            save_flows=False,
-            filename=f"{name}.chd",
-        )
-
-        # MAW
-        maw = flopy.mf6.ModflowGwfmaw(
-            gwf,
-            filename=f"{name}.maw",
-            budget_filerecord=f"{name}.maw.cbc",
-            print_input=True,
-            print_head=True,
-            print_flows=True,
-            save_flows=True,
-            observations=data.well.observations,
-            packagedata=data.well.packagedata,
-            connectiondata=data.well.connectiondata,
-            perioddata=data.well.perioddata,
-            pname="MAW-1",
-        )
-
-        # output control
-        oc = flopy.mf6.ModflowGwfoc(
-            gwf,
-            budget_filerecord=f"{name}.cbc",
-            head_filerecord=f"{name}.hds",
-            headprintrecord=[
-                ("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")
-            ],
-            saverecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
-            printrecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
-            filename=f"{name}.oc",
-        )
-
-        return data, sim, None, self.eval_2
-
-    def eval_2(self, config, data):
-        print("evaluating MAW budgets...")
-
-        shape3d = (data.nlay, data.nrow, data.ncol)
-        size3d = data.nlay * data.nrow * data.ncol
-
-        # get results from listing file
-        fpth = os.path.join(
-            config.simpath, f"{os.path.basename(config.name)}.lst"
-        )
-        budl = flopy.utils.Mf6ListBudget(
-            fpth, budgetkey="MAW-1 BUDGET FOR ENTIRE MODEL AT END OF TIME STEP"
-        )
-        names = list(self.bud_lst)
-        d0 = budl.get_budget(names=names)[0]
-        dtype = d0.dtype
-        nbud = d0.shape[0]
-
-        # get results from cbc file
-        cbc_bud = ["GWF", "RATE"]
-        d = np.recarray(nbud, dtype=dtype)
-        for key in self.bud_lst:
-            d[key] = 0.0
-        fpth = os.path.join(
-            config.simpath, f"{os.path.basename(config.name)}.maw.cbc"
-        )
-        cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
-        kk = cobj.get_kstpkper()
-        times = cobj.get_times()
-        cbc_vals = []
-        for idx, (k, t) in enumerate(zip(kk, times)):
-            for text in cbc_bud:
-                qin = 0.0
-                qout = 0.0
-                v = cobj.get_data(kstpkper=k, text=text)[0]
-                if isinstance(v, np.recarray):
-                    vt = np.zeros(size3d, dtype=float)
-                    wq = []
-                    for jdx, node in enumerate(v["node"]):
-                        vt[node - 1] += v["q"][jdx]
-                        wq.append(v["q"][jdx])
-                    v = vt.reshape(shape3d)
-                    if text == cbc_bud[-1]:
-                        cbc_vals.append(wq)
-                for kk in range(v.shape[0]):
-                    for ii in range(v.shape[1]):
-                        for jj in range(v.shape[2]):
-                            vv = v[kk, ii, jj]
-                            if vv < 0.0:
-                                qout -= vv
-                            else:
-                                qin += vv
-                d["totim"][idx] = t
-                d["time_step"][idx] = k[0]
-                d["stress_period"] = k[1]
-                key = f"{text}_IN"
-                d[key][idx] = qin
-                key = f"{text}_OUT"
-                d[key][idx] = qout
-
-        maw_vals = [
-            [0.000, 0.000],
-            [-106.11303563809453, -96.22598985147631],
-            [-110.000, -130.000],
-            [0.0, -130.000],
-            [-110.000, -130.000],
-        ]
-
-        # evaluate if well rates in cbc file are equal to expected values
-        diffv = []
-        for ovs, svs in zip(maw_vals, cbc_vals):
-            for ov, sv in zip(ovs, svs):
-                diffv.append(ov - sv)
-        diffv = np.abs(np.array(diffv)).max()
-        msg = f"\nmaximum absolute maw rate difference     ({diffv})\n"
-
-        # calculate difference between water budget items in the lst and cbc files
-        diff = np.zeros((nbud, len(self.bud_lst)), dtype=float)
-        for idx, key in enumerate(self.bud_lst):
-            diff[:, idx] = d0[key] - d[key]
-        diffmax = np.abs(diff).max()
-        msg += f"maximum absolute total-budget difference ({diffmax}) "
-
-        # write summary
-        fpth = os.path.join(
-            config.simpath, f"{os.path.basename(config.name)}.bud.cmp.out"
-        )
-        f = open(fpth, "w")
-        for i in range(diff.shape[0]):
-            if i == 0:
-                line = f"{'TIME':>10s}"
-                for idx, key in enumerate(self.bud_lst):
-                    line += f"{key + '_LST':>25s}"
-                    line += f"{key + '_CBC':>25s}"
-                    line += f"{key + '_DIF':>25s}"
-                f.write(line + "\n")
-            line = f"{d['totim'][i]:10g}"
-            for idx, key in enumerate(self.bud_lst):
-                line += f"{d0[key][i]:25g}"
-                line += f"{d[key][i]:25g}"
-                line += f"{diff[i, idx]:25g}"
-            f.write(line + "\n")
-        f.close()
-
-        if diffmax > self.budtol or diffv > self.budtol:
-            config.success = False
-            msg += f"\n...exceeds {self.budtol}"
-            assert diffmax < self.budtol, msg
-        else:
-            config.success = True
-            print("    " + msg)
-
-    case3 = Case(
-        name="maw03",
-        krylov="CG",
-        nlay=1,
-        nrow=101,
-        ncol=101,
-        nper=1,
-        delr=142,
-        delc=142,
-        perlen=[1000],
-        nstp=[50],
-        tsmult=[1.2],
-        strt=0,
-        hk=10,
-        nouter=100,
-        ninner=100,
-        hclose=1e-6,
-        rclose=1e-6,
-        relaxation_factor=1,
-        compare=False,
-    )
-    cases3 = [
-        case3.copy_update(
-            name="maw03a",
-            well=well3("maw03a"),
-        ),
-        case3.copy_update(name="maw03b", well=well3("maw03b")),
-        case3.copy_update(name="maw03c", well=well3("maw03c")),
-    ]
-
-    @parametrize(data=cases3, ids=[c.name for c in cases3])
-    def case_3(self, function_tmpdir, targets, data):
-        top = 0.0
-        botm = [-1000.0]
-
-        tdis_rc = []
-        for i in range(data.nper):
-            tdis_rc.append((data.perlen[i], data.nstp[i], data.tsmult[i]))
-
-        name = data.name
-        ws = str(function_tmpdir)
-        sim = flopy.mf6.MFSimulation(
-            sim_name=name, sim_ws=ws, exe_name=targets["mf6"]
-        )
-
-        # create tdis package
-        tdis = flopy.mf6.ModflowTdis(
-            sim, time_units="DAYS", nper=data.nper, perioddata=tdis_rc
-        )
-
-        # create gwf model
-        gwf = flopy.mf6.MFModel(
-            sim,
-            model_type="gwf6",
-            modelname=name,
-            model_nam_file=f"{name}.nam",
-        )
-
-        # create iterative model solution and register the gwf model with it
-        ims = flopy.mf6.ModflowIms(
-            sim,
-            print_option="SUMMARY",
-            outer_dvclose=data.hclose,
-            outer_maximum=data.nouter,
-            under_relaxation="NONE",
-            inner_maximum=data.ninner,
-            inner_dvclose=data.hclose,
-            rcloserecord=data.rclose,
-            linear_acceleration=data.krylov,
-            scaling_method="NONE",
-            reordering_method="NONE",
-            relaxation_factor=data.relaxation_factor,
-        )
-        sim.register_ims_package(ims, [gwf.name])
-
-        dis = flopy.mf6.ModflowGwfdis(
-            gwf,
-            nlay=data.nlay,
-            nrow=data.nrow,
-            ncol=data.ncol,
-            delr=data.delr,
-            delc=data.delc,
-            top=top,
-            botm=botm,
-            idomain=1,
-            filename=f"{name}.dis",
-        )
-
-        # initial conditions
-        ic = flopy.mf6.ModflowGwfic(gwf, strt=data.strt, filename=f"{name}.ic")
-
-        # node property flow
-        npf = flopy.mf6.ModflowGwfnpf(
-            gwf,
-            save_flows=True,
-            icelltype=1,
-            k=data.hk,
-            k33=data.hk,
-            filename=f"{name}.npf",
-        )
-
-        # storage
-        sto = flopy.mf6.ModflowGwfsto(
-            gwf,
-            save_flows=True,
-            iconvert=0,
-            ss=1.0e-5,
-            sy=0.1,
-            steady_state={0: False},
-            transient={0: True},
-            filename=f"{name}.sto",
-        )
-
-        # MAW
-        maw = flopy.mf6.ModflowGwfmaw(
-            gwf,
-            filename=f"{name}.maw",
-            print_input=True,
-            print_head=True,
-            print_flows=True,
-            save_flows=True,
-            observations=data.well.observations,
-            packagedata=data.well.packagedata,
-            connectiondata=data.well.connectiondata,
-            perioddata=data.well.perioddata,
-        )
-
-        # output control
-        oc = flopy.mf6.ModflowGwfoc(
-            gwf,
-            budget_filerecord=f"{name}.cbc",
-            head_filerecord=f"{name}.hds",
-            headprintrecord=[
-                ("COLUMNS", data.ncol, "WIDTH", 15, "DIGITS", 6, "GENERAL")
-            ],
-            saverecord=[("HEAD", "ALL")],
-            printrecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
-            filename=f"{name}.oc",
-        )
-
-        # head observations
-        obs_data0 = [("head_well_cell", "HEAD", (0, 0, 0))]
-        obs_recarray = {f"{name}.obs.csv": obs_data0}
-        obs = flopy.mf6.ModflowUtlobs(
-            gwf,
-            pname="head_obs",
-            filename=f"{name}.obs",
-            digits=15,
-            print_input=True,
-            continuous=obs_recarray,
-        )
-
-        return data, sim, None, self.eval_3
-
-    def eval_3(self, config, data):
-        print("evaluating MAW heads...")
-
-        # MODFLOW 6 maw results
-        test_name = config.name
-        case_name = data.name
-        fpth = os.path.join(config.simpath, f"{test_name}.maw.obs.csv")
-        tc = np.genfromtxt(fpth, names=True, delimiter=",")
-
-        if case_name == "a":
-
-            # M1RATE should be 2000.
-            msg = "The injection rate should be 2000. for all times"
-            assert tc["M1RATE"].min() == tc["M1RATE"].max() == 2000, msg
-
-        elif case_name == "b":
-
-            # M1RATE should have a minimum value less than 200 and
-            # M1HEAD should not exceed 0.400001
-            msg = (
-                "Injection rate should fall below 200 and the head should not"
-                "exceed 0.4"
-            )
-            assert tc["M1RATE"].min() < 200.0, msg
-            assert tc["M1HEAD"].max() < 0.400001, msg
-
-        elif case_name == "c":
-
-            # M1RATE should have a minimum value less than 800
-            # M1HEAD should not exceed 1.0.
-            msg = (
-                "Min injection rate should be less than 800 and well "
-                "head should not exceed 1.0"
-            )
-            assert tc["M1RATE"].min() < 800.0 and tc["M1HEAD"].max() < 1.0, msg
-
-    # TODO
-    # case4 = Case(
-    #     name='maw_iss305',
-    #     krylov='CG',
-    #     nlay=2,
-    #     nrow=101,
-    #     ncol=101,
-    #     nper=2,
-    #     delr=142,
-    #     delc=142,
-    #     perlen=[0.0, 365.0],
-    #     nstp=[1, 25],
-    #     tsmult=[1.0, 1.1],
-    #     steady=[True, False],
-    #     well=None,
-    #     strt=0,
-    #     hk=10,
-    #     nouter=100,
-    #     ninner=100,
-    #     hclose=1e-9,
-    #     rclose=1e-6,
-    #     relax=1,
-    #     require_failure=True
-    # )
-    # cases4 = [
-    #     case4.copy_update({
-    #         'name': "maw_iss305a",
-    #         'well': well4(case4, "CUMULATIVE"),
-    #         'require_failure': False
-    #     }),
-    #     case4.copy_update({
-    #         'name': "maw_iss305b",
-    #         'well': well4(case4, "SKIN")
-    #     }),
-    #     case4.copy_update({
-    #         'name': "maw_iss305c",
-    #         'well': well4(case4, "SKIN")
-    #     }),
-    #     case4.copy_update({
-    #         'name': "maw_iss305d",
-    #         'well': well4(case4, "SKIN")
-    #     }),
-    #     case4.copy_update({
-    #         'name': "maw_iss305e",
-    #         'well': well4(case4, "SPECIFIED")
-    #     }),
-    #     case4.copy_update({
-    #         'name': "maw_iss305f",
-    #         'well': well4(case4, "CUMULATIVE")
-    #     })
-    # ]
-
-    # @parametrize(data=cases4, ids=[c['name'] for c in cases4])
-    # def case_4(self, function_tmpdir, targets, data):
-    #     pass
-
-    # def eval_4(self, sim, data):
-    #     pass
diff --git a/autotest/test_gwf_maw_obs.py b/autotest/test_gwf_maw_obs.py
index 7455949fc37..1b9666878b5 100644
--- a/autotest/test_gwf_maw_obs.py
+++ b/autotest/test_gwf_maw_obs.py
@@ -1,20 +1,20 @@
-# Test for checking maw observation input.  The following observation types:
-# 'maw' and 'conductance,' require that ID2 be provided when
-# ID is an integer corresponding to a well number and not BOUNDNAME.
-# See table in MAW Package section of mf6io.pdf for an explanation of ID,
-# ID2, and Observation Type.
-
+"""
+Test for checking maw observation input.  The following observation types:
+'maw' and 'conductance,' require that ID2 be provided when
+ID is an integer corresponding to a well number and not BOUNDNAME.
+See table in MAW Package section of mf6io.pdf for an explanation of ID,
+ID2, and Observation Type.
+"""
 
 import os
 
 import flopy
 
 newtonoptions = [None, "NEWTON", "NEWTON UNDER_RELAXATION"]
-ex = "maw_obs"
+cases = "maw_obs"
 
 
 def build_model(dir, exe):
-
     nlay, nrow, ncol = 1, 1, 3
     nper = 3
     perlen = [1.0, 1.0, 1.0]
@@ -35,7 +35,7 @@ def build_model(dir, exe):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex
+    name = cases
 
     # build MODFLOW 6 files
     ws = dir
@@ -188,8 +188,8 @@ def test_mf6model(function_tmpdir, targets):
     )
 
     # fix the error and attempt to rerun model
-    orig_fl = str(function_tmpdir / (ex + ".maw.obs"))
-    new_fl = str(function_tmpdir / (ex + ".maw.obs.new"))
+    orig_fl = str(function_tmpdir / (cases + ".maw.obs"))
+    new_fl = str(function_tmpdir / (cases + ".maw.obs.new"))
     sr = open(orig_fl, "r")
     sw = open(new_fl, "w")
 
@@ -210,5 +210,4 @@ def test_mf6model(function_tmpdir, targets):
 
     # rerun the model, should be no errors
     success, buff = sim.run_simulation()
-
-    assert success, "model rerun failed"
+    assert success, buff
diff --git a/autotest/test_gwf_mf6io_app2_examples_distypes.py b/autotest/test_gwf_mf6io_app2_examples_distypes.py
new file mode 100644
index 00000000000..542b3e694f0
--- /dev/null
+++ b/autotest/test_gwf_mf6io_app2_examples_distypes.py
@@ -0,0 +1,569 @@
+import pathlib as pl
+
+import flopy
+import numpy as np
+import pytest
+from flopy.utils.gridgen import Gridgen
+from conftest import try_get_target
+
+from framework import TestFramework
+
+dis_types = (
+    "disv",
+    "disu",
+)
+problems = (
+    "ps1a",
+    "ps2a",
+    "ps2b",
+    "ps2c",
+    "ps2c1",
+    "ps2d",
+    "ps2e",
+)
+cases = []
+for problem in problems:
+    cases += [f"{problem}_{dis_type}" for dis_type in dis_types]
+
+# base spatial discretization
+nlay, nrow, ncol = 3, 21, 20
+shape3d = (nlay, nrow, ncol)
+shape2d = (nrow, ncol)
+size3d = nlay * nrow * ncol
+size2d = nrow * ncol
+
+delr = delc = 500.0
+x0_base, x1_base, y0_base, y1_base = 0, ncol * delr, 0.0, nrow * delc
+top = 400.0
+bot = 0.0
+botm = [220.0, 200.0, 0.0]
+z_node = [310.0, 210.0, 100.0]
+
+hk = [50.0, 0.01, 200.0]
+vk = [10.0, 0.01, 20.0]
+
+concentration = 1.0
+
+canal_head = 330.0
+canal_coordinates = [
+    (0.5 * delr, y1_base - delc * (i + 0.5)) for i in range(nrow)
+]
+
+river_head = 320.0
+river_coordinates = [
+    (x1_base - 0.5 * delr, y1_base - delc * (i + 0.5)) for i in range(nrow)
+]
+
+rch_rate = 0.005
+
+drain_coordinates = [
+    (x0_base + (j + 0.5) * delr, y1_base - 14.5 * delc) for j in range(9, ncol)
+]
+
+well_coordinates = [
+    (x0_base + 9.5 * delr, y1_base - 10.5 * delc),
+    (x0_base + 4.5 * delr, y1_base - 12.5 * delc),
+]
+wellq = (
+    -75000.0,
+    -100000.0,
+)
+well_layers = (
+    0,
+    2,
+)
+
+
+def build_dis(gwf):
+    return flopy.mf6.ModflowGwfdis(
+        gwf,
+        length_units="FEET",
+        nlay=nlay,
+        nrow=nrow,
+        ncol=ncol,
+        delr=delr,
+        delc=delc,
+        top=top,
+        botm=botm,
+    )
+
+
+def get_gridgen_ws(ws):
+    gridgen_ws = ws / "gridgen"
+    gridgen_ws.mkdir(parents=True, exist_ok=True)
+    return gridgen_ws
+
+
+def get_dis_name(name):
+    return name.replace("disv", "dis").replace("disu", "dis")
+
+
+def build_temp_gwf(ws):
+    gridgen_ws = get_gridgen_ws(ws)
+    gridgen_sim = flopy.mf6.MFSimulation(
+        sim_name="gridgen", sim_ws=gridgen_ws, exe_name="mf6"
+    )
+    gridgen_gwf = flopy.mf6.ModflowGwf(gridgen_sim, modelname="gridgen")
+    return gridgen_gwf
+
+
+def build_disv(ws, gwf, gridgen):
+    temp_gwf = build_temp_gwf(ws)
+    dis = build_dis(temp_gwf)
+    g = Gridgen(
+        temp_gwf.modelgrid,
+        model_ws=get_gridgen_ws(ws),
+        exe_name=gridgen,
+    )
+    g.build()
+    gridprops = g.get_gridprops_disv()
+    gridprops["top"] = top
+    gridprops["botm"] = botm
+    return flopy.mf6.ModflowGwfdisv(
+        gwf,
+        length_units="FEET",
+        **gridprops,
+    )
+
+
+def build_disu(ws, gwf, gridgen):
+    temp_gwf = build_temp_gwf(ws)
+    dis = build_dis(temp_gwf)
+    g = Gridgen(
+        temp_gwf.modelgrid,
+        model_ws=get_gridgen_ws(ws),
+        exe_name=gridgen,
+    )
+    g.build()
+    gridprops = g.get_gridprops_disu6()
+    return flopy.mf6.ModflowGwfdisu(
+        gwf,
+        length_units="FEET",
+        **gridprops,
+    )
+
+
+def get_node_number(modelgrid, cellid):
+    if modelgrid.grid_type == "unstructured":
+        node = cellid
+    elif modelgrid.grid_type == "vertex":
+        node = modelgrid.ncpl * cellid[0] + cellid[1]
+    else:
+        node = (
+            modelgrid.nrow * modelgrid.ncol * cellid[0]
+            + modelgrid.ncol * cellid[1]
+            + cellid[2]
+        )
+    return node
+
+
+def build_3d_array(modelgrid, values, dtype=float):
+    if isinstance(values, dtype):
+        arr = np.full(modelgrid.nnodes, values, dtype=dtype)
+    else:
+        arr = np.zeros(modelgrid.nnodes, dtype=dtype)
+        ia = []
+        x0, x1, y0, y1 = modelgrid.extent
+        for k in range(nlay):
+            cellid = modelgrid.intersect(x0 + 0.1, y1 - 0.1, z=z_node[k])
+            ia.append(get_node_number(modelgrid, cellid))
+        ia.append(modelgrid.nnodes + 1)
+        for k in range(nlay):
+            arr[ia[k] : ia[k + 1]] = values[k]
+    return arr.reshape(modelgrid.shape)
+
+
+def build_chd_data(
+    modelgrid,
+    coordinates,
+    head,
+    layer_number=0,
+    boundname="canal",
+):
+    chd_spd = []
+    for x, y in coordinates:
+        cellid = modelgrid.intersect(x, y, z=z_node[layer_number])
+        if isinstance(cellid, int):
+            cellid = (cellid,)
+        chd_spd.append((cellid, head, concentration, boundname))
+    return {0: chd_spd}
+
+
+def build_riv_data(modelgrid):
+    cond = 20.0 * 10 * delc / 1.0
+    spd = []
+    for x, y in river_coordinates:
+        cellid = modelgrid.intersect(x, y, z=z_node[0])
+        if isinstance(cellid, int):
+            cellid = (cellid,)
+        spd.append((*cellid, river_head, cond, 317.0, concentration, "river"))
+    return {0: spd}
+
+
+def build_drn_data(modelgrid, boundname="drain"):
+    cond = 100000.0
+    drain_elev = 322.5
+    spd = []
+    for x, y in drain_coordinates:
+        cellid = modelgrid.intersect(x, y, z=z_node[0])
+        if isinstance(cellid, int):
+            cellid = (cellid,)
+        spd.append((*cellid, drain_elev, cond, concentration, boundname))
+    return {0: spd}
+
+
+def build_well_data(modelgrid, nper):
+    spd_dict = {}
+    for iper in range(nper):
+        if iper > 1:
+            continue
+        if iper == 0:
+            iend = 1
+        else:
+            iend = 2
+        spd = []
+        for i, (x, y) in enumerate(well_coordinates[:iend]):
+            cellid = modelgrid.intersect(x, y, z=z_node[well_layers[i]])
+            if isinstance(cellid, int):
+                cellid = (cellid,)
+            spd.append((*cellid, wellq[i], concentration, f"well-{i+1}"))
+        spd_dict[iper] = spd
+    return spd_dict
+
+
+def build_rch_package(gwf, list_recharge):
+    if list_recharge:
+        spd = []
+        for i in range(nrow):
+            y = y1_base - delr * (i + 0.5)
+            for j in range(ncol):
+                x = delc * (j + 0.5)
+                cellid = gwf.modelgrid.intersect(x, y, z=z_node[0])
+                if isinstance(cellid, int):
+                    cellid = (cellid,)
+                spd.append((*cellid, rch_rate, concentration, "recharge"))
+        rch = flopy.mf6.ModflowGwfrch(
+            gwf,
+            auxiliary=["concentration"],
+            boundnames=True,
+            stress_period_data=spd,
+        )
+    else:
+        rch = flopy.mf6.ModflowGwfrcha(gwf, recharge=rch_rate)
+    return rch
+
+
+def build_models(idx, test):
+    gridgen = try_get_target(test.targets, "gridgen")
+    return build_mf6(idx, test.workspace, gridgen), build_mf6(
+        idx, test.workspace / "mf6", gridgen
+    )
+
+
+# build MODFLOW 6 files
+def build_mf6(idx, ws, gridgen):
+    if ws.name == "mf6":
+        dis_type = "dis"
+    elif "disv" in str(ws):
+        dis_type = "disv"
+    elif "disu" in str(ws):
+        dis_type = "disu"
+    else:
+        raise ValueError(f"Invalid discretization type in {str(ws)}")
+
+    if "disu" in str(ws):
+        list_recharge = True
+    else:
+        list_recharge = False
+
+    name = cases[idx]
+    if dis_type == "dis":
+        name = get_dis_name(name)
+    sim_name = name[0:3]
+
+    sim = flopy.mf6.MFSimulation(
+        sim_name=sim_name,
+        version="mf6",
+        exe_name="mf6",
+        sim_ws=ws,
+    )
+    # create tdis package
+    if "ps2e" in name:
+        nper = 3
+        perioddata = (
+            (300000.0, 1, 1.0),
+            (36500.0, 10, 1.5),
+            (300000.0, 1, 1.0),
+        )
+
+    else:
+        nper = 1
+        perioddata = ((1.0, 1, 1.0),)
+
+    tdis = flopy.mf6.ModflowTdis(
+        sim,
+        time_units="DAYS",
+        nper=nper,
+        perioddata=perioddata,
+    )
+
+    # create iterative model solution and register the gwf model with it
+    ims = flopy.mf6.ModflowIms(
+        sim,
+        print_option="SUMMARY",
+        complexity="simple",
+    )
+
+    # create gwf model
+    gwf = flopy.mf6.ModflowGwf(
+        sim,
+        modelname=sim_name,
+        print_input=True,
+        print_flows=True,
+        save_flows=True,
+    )
+
+    if dis_type == "disv":
+        dis = build_disv(ws, gwf, gridgen)
+    elif dis_type == "disu":
+        dis = build_disu(ws, gwf, gridgen)
+    else:
+        dis = build_dis(gwf)
+
+    # initial conditions
+    if dis_type == "disu":
+        strt = top
+    else:
+        strt = [top, top, top]
+    ic = flopy.mf6.ModflowGwfic(
+        gwf,
+        strt=strt,
+    )
+
+    if dis_type in ("dis", "disv"):
+        k11 = hk
+        k33 = vk
+        icelltype = [1, 0, 0]
+    else:
+        k11 = build_3d_array(gwf.modelgrid, hk)
+        k33 = build_3d_array(gwf.modelgrid, vk)
+        icelltype = build_3d_array(gwf.modelgrid, [1, 0, 0], dtype=int)
+
+    # node property flow
+    npf = flopy.mf6.ModflowGwfnpf(
+        gwf,
+        icelltype=icelltype,
+        k=k11,
+        k33=k33,
+    )
+
+    if nper > 1:
+        sto = flopy.mf6.ModflowGwfsto(
+            gwf,
+            ss=0.0001,
+            sy=0.1,
+            iconvert=1,
+            steady_state={0: True, 2: True},
+            transient={1: True},
+        )
+
+    # canal chd
+    if name.startswith("ps1"):
+        canal_chd = flopy.mf6.ModflowGwfchd(
+            gwf,
+            auxiliary=["concentration"],
+            boundnames=True,
+            filename=f"{name}.canal.chd",
+            pname="canal",
+            stress_period_data=build_chd_data(
+                gwf.modelgrid,
+                canal_coordinates,
+                canal_head,
+                boundname="canal",
+            ),
+        )
+
+    if name.startswith("ps1") or name.startswith("ps2a"):
+        river_chd = flopy.mf6.ModflowGwfchd(
+            gwf,
+            auxiliary=["concentration"],
+            boundnames=True,
+            filename=f"{name}.river.chd",
+            pname="river",
+            stress_period_data=build_chd_data(
+                gwf.modelgrid,
+                river_coordinates,
+                river_head,
+                boundname="river",
+            ),
+        )
+    else:
+        river_riv = flopy.mf6.ModflowGwfriv(
+            gwf,
+            auxiliary=["concentration"],
+            boundnames=True,
+            pname="river",
+            stress_period_data=build_riv_data(
+                gwf.modelgrid,
+            ),
+        )
+
+    if name.startswith("ps2"):
+        rch = build_rch_package(gwf, list_recharge)
+
+    if "ps2c" in name or "ps2d" in name or "ps2e" in name:
+        if "ps2c1" in name:
+            ghb = flopy.mf6.ModflowGwfghb(
+                gwf,
+                auxiliary=["concentration"],
+                boundnames=True,
+                stress_period_data=build_drn_data(
+                    gwf.modelgrid,
+                    boundname="ghb-1",
+                ),
+            )
+        else:
+            drn = flopy.mf6.ModflowGwfdrn(
+                gwf,
+                auxiliary=["concentration"],
+                boundnames=True,
+                stress_period_data=build_drn_data(gwf.modelgrid),
+            )
+
+    if "ps2d" in name or "ps2e" in name:
+        wel = flopy.mf6.ModflowGwfwel(
+            gwf,
+            auxiliary=["concentration"],
+            boundnames=True,
+            stress_period_data=build_well_data(gwf.modelgrid, nper=nper),
+        )
+
+    # output control
+    oc = flopy.mf6.ModflowGwfoc(
+        gwf,
+        budget_filerecord=f"{sim_name}.cbc",
+        head_filerecord=f"{sim_name}.hds",
+        headprintrecord=[("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")],
+        saverecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
+        printrecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
+    )
+    return sim
+
+
+def check_output(idx, test):
+    name = cases[idx]
+    sim_name = name[0:3]
+    ws = pl.Path(test.workspace)
+
+    if name.startswith("ps1"):
+        row_values = np.array(
+            [
+                330.000,
+                329.259,
+                328.600,
+                328.008,
+                327.473,
+                326.983,
+                326.529,
+                326.102,
+                325.694,
+                325.297,
+                324.903,
+                324.504,
+                324.092,
+                323.659,
+                323.195,
+                322.691,
+                322.133,
+                321.510,
+                320.805,
+                320.000,
+            ]
+        )
+    elif name.startswith("ps2a"):
+        row_values = np.array(
+            [
+                346.054,
+                345.979,
+                345.828,
+                345.598,
+                345.286,
+                344.886,
+                344.391,
+                343.792,
+                343.079,
+                342.238,
+                341.251,
+                340.099,
+                338.755,
+                337.189,
+                335.362,
+                333.224,
+                330.714,
+                327.750,
+                324.227,
+                320.000,
+            ]
+        )
+    elif name.startswith("ps2b"):
+        row_values = np.array(
+            [
+                346.268,
+                346.193,
+                346.042,
+                345.813,
+                345.500,
+                345.100,
+                344.606,
+                344.008,
+                343.295,
+                342.454,
+                341.468,
+                340.316,
+                338.974,
+                337.410,
+                335.584,
+                333.449,
+                330.943,
+                327.984,
+                324.468,
+                320.250,
+            ]
+        )
+    else:
+        row_values = None
+    if row_values is None:
+        answer = None
+    else:
+        answer = np.zeros(shape2d)
+        for i in range(nrow):
+            answer[i, :] = row_values[:]
+
+    # get disv or disu simulation
+    sim_base = flopy.mf6.MFSimulation.load(sim_name=sim_name, sim_ws=ws)
+    gwf_base = sim_base.get_model()
+
+    head = gwf_base.output.head().get_data().flatten().reshape(shape3d)
+    if answer is not None:
+        assert np.allclose(
+            head[0], answer
+        ), "head data for first layer does not match know result"
+
+    extension = "cbc"
+    fpth0 = ws / f"{sim_name}.{extension}"
+    # fpth1 = ws / f"mf6/{get_dis_name(name)}.{extension}"
+    fpth1 = ws / f"mf6/{sim_name}.{extension}"
+    test._compare_budget_files(extension, fpth0, fpth1)
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        verbose=False,
+    )
+    test.run()
diff --git a/autotest/test_gwf_multimvr.py b/autotest/test_gwf_multimvr.py
index 9fddf576be0..f85ce24ce7f 100644
--- a/autotest/test_gwf_multimvr.py
+++ b/autotest/test_gwf_multimvr.py
@@ -5,10 +5,10 @@
 import numpy as np
 import pytest
 from flopy.utils.lgrutil import Lgr
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-mvr_scens = ["mltmvr", "mltmvr5050", "mltmvr7525"]
+cases = ["mltmvr", "mltmvr5050", "mltmvr7525"]
 sim_workspaces = []
 gwf_names = []
 
@@ -837,7 +837,8 @@ def add_parent_sfr(gwf, gwfname, conns):
         print_flows=True,
         mover=True,
         pname="SFR-parent",
-        unit_conversion=86400.00,
+        length_conversion=1.0,
+        time_conversion=86400.0,
         boundnames=False,
         nreaches=len(conns),
         packagedata=pkdat,
@@ -857,7 +858,8 @@ def add_child_sfr(gwfc, gwfnamec):
         print_flows=True,
         mover=True,
         pname="SFR-child",
-        unit_conversion=86400.00,
+        length_conversion=1.0,
+        time_conversion=86400.0,
         boundnames=False,
         nreaches=len(connsc),
         packagedata=pkdatc,
@@ -970,17 +972,16 @@ def add_sim_mvr(sim, gwfname, gwfnamec, remaining_frac=None):
     )
 
 
-def build_model(idx, sim_ws):
-
+def build_models(idx, test):
     scen_nm, conns, frac = (
-        mvr_scens[idx],
+        cases[idx],
         scen_conns[idx],
         parent_mvr_frac[idx],
     )
     scen_nm_parent = "gwf_" + scen_nm + "_p"
     scen_nm_child = "gwf_" + scen_nm + "_c"
     sim, gwf, gwfc = instantiate_base_simulation(
-        sim_ws, scen_nm_parent, scen_nm_child
+        test.workspace, scen_nm_parent, scen_nm_child
     )
     # add the sfr packages
     add_parent_sfr(gwf, scen_nm_parent, conns)
@@ -996,9 +997,7 @@ def build_model(idx, sim_ws):
     return sim, None
 
 
-def check_simulation_output(sim):
-    idx = sim.idxsim
-
+def check_output(idx, test):
     gwf_srch_str1 = (
         " SFR-PARENT PACKAGE - SUMMARY OF FLOWS FOR EACH CONTROL VOLUME"
     )
@@ -1006,8 +1005,8 @@ def check_simulation_output(sim):
     sim_srch_str = " WATER MOVER PACKAGE (MVR) FLOW RATES "
 
     # cur_ws, gwfparent = ex[idx], gwf_names[idx]
-    cur_ws = sim.simpath
-    gwfparent = "gwf_" + mvr_scens[idx] + "_p"
+    cur_ws = test.workspace
+    gwfparent = "gwf_" + cases[idx] + "_p"
     with open(os.path.join(cur_ws, gwfparent + ".lst"), "r") as gwf_lst, open(
         os.path.join(cur_ws, "mfsim.lst"), "r"
     ) as sim_lst:
@@ -1068,9 +1067,13 @@ def check_simulation_output(sim):
     #    - 50/50: ~107 units of flow in each
     #    - 75/25: 75% goes through the gwf mvr, 25% through the simulation mvr
     q_target = 214.25
-    assert math.isclose(parent_sfr_last_reach_flow, q_target, rel_tol=0.1,), (
+    assert math.isclose(
+        parent_sfr_last_reach_flow,
+        q_target,
+        rel_tol=0.1,
+    ), (
         "Flow in the last reach of scenario "
-        + mvr_scens[idx]
+        + cases[idx]
         + " = "
         + str(parent_sfr_last_reach_flow)
         + ", whereas the target flow "
@@ -1114,19 +1117,13 @@ def check_simulation_output(sim):
         )
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(mvr_scens)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=check_simulation_output,
-            idxsim=idx,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_mvr01.py b/autotest/test_gwf_mvr01.py
index 8ba4f45b1e1..0913dbc40c2 100644
--- a/autotest/test_gwf_mvr01.py
+++ b/autotest/test_gwf_mvr01.py
@@ -3,19 +3,19 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
 name = "gwf_mvr01"
-ex = [name]
+cases = [name]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     # static model data
     # temporal discretization
     nper = 1
     tdis_rc = []
-    for idx in range(nper):
+    for _ in range(nper):
         tdis_rc.append((1.0, 1, 1.0))
 
     # spatial discretization data
@@ -36,7 +36,7 @@ def build_model(idx, dir):
 
     # build MODFLOW 6 files
     sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name="mf6", sim_ws=str(dir)
+        sim_name=name, version="mf6", exe_name="mf6", sim_ws=test.workspace
     )
     # create tdis package
     tdis = flopy.mf6.ModflowTdis(
@@ -372,11 +372,9 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
+def check_output(idx, test):
     # mvr budget terms
-    fpth = os.path.join(sim.simpath, "gwf_mvr01.mvr.bud")
+    fpth = os.path.join(test.workspace, "gwf_mvr01.mvr.bud")
     bobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     times = bobj.get_times()
     records = bobj.get_data(totim=times[-1])
@@ -446,17 +444,13 @@ def eval_model(sim):
     assert records[24].shape == (0,)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_newton01.py b/autotest/test_gwf_newton01.py
index 60c83c8f768..e184e92da20 100644
--- a/autotest/test_gwf_newton01.py
+++ b/autotest/test_gwf_newton01.py
@@ -3,10 +3,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["newton01"]
+cases = ["newton01"]
 nlay = 2
 nrow, ncol = 3, 3
 top = 20
@@ -22,7 +22,7 @@
 obs_recarray = {oname: [("h1", "HEAD", (0, 1, 1)), ("h2", "HEAD", (1, 1, 1))]}
 
 
-def build_model(idx, ws):
+def build_models(idx, test):
     c6 = []
     for loc in chdloc:
         c6.append([loc, chd])
@@ -31,11 +31,11 @@ def build_model(idx, ws):
     nper = 1
     tdis_rc = [(1.0, 1, 1.0)]
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
     sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
+        sim_name=name, version="mf6", exe_name="mf6", sim_ws=test.workspace
     )
     # create tdis package
     flopy.mf6.ModflowTdis(
@@ -97,9 +97,8 @@ def build_model(idx, ws):
     return sim, None
 
 
-def eval_head(sim):
-    print("evaluating heads...")
-    fpth = os.path.join(sim.simpath, oname)
+def check_output(idx, test):
+    fpth = os.path.join(test.workspace, oname)
     v = np.genfromtxt(fpth, delimiter=",", names=True)
 
     msg = f"head in layer 1 != 8. ({v['H1']})"
@@ -109,12 +108,13 @@ def eval_head(sim):
     assert np.allclose(v["H2"], 7.0), msg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(TestSimulation(name=name, exe_dict=targets, exfunc=eval_head), ws)
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+    )
+    test.run()
diff --git a/autotest/test_gwf_newton_under_relaxation.py b/autotest/test_gwf_newton_under_relaxation.py
new file mode 100644
index 00000000000..9fedb1875a8
--- /dev/null
+++ b/autotest/test_gwf_newton_under_relaxation.py
@@ -0,0 +1,135 @@
+import pathlib as pl
+
+import flopy
+import numpy as np
+import pytest
+
+from conftest import project_root_path
+from framework import TestFramework
+
+cases = ["nr_ur01", "nr_ur02"]
+data_path = project_root_path / "autotest/data/ex-gwf-bump/"
+nper = 1
+nlay = 1
+nrow = 51
+ncol = 51
+xlen = 100.0
+ylen = 100.0
+top = 25.0
+k11 = 1.0
+H1 = 7.5
+H2 = 2.5
+delr = xlen / float(ncol)
+delc = ylen / float(nrow)
+extents = (0, xlen, 0, ylen)
+shape2d = (nrow, ncol)
+shape3d = (nlay, nrow, ncol)
+nouter = 50
+ninner = 100
+hclose = 1e-9
+hclose_outer = hclose * 10.0
+rclose = 1e-3
+botm = np.loadtxt(data_path / "bottom.txt").reshape(shape3d)
+chd_spd = [[0, i, 0, H1] for i in range(nrow)]
+chd_spd += [[0, i, ncol - 1, H2] for i in range(nrow)]
+base_heads = flopy.utils.HeadFile(data_path / "results.hds.cmp").get_data()
+
+
+def build_models(idx, test):
+    name = cases[idx]
+    if idx == 1:
+        sim_ws = pl.Path(f"{test.workspace}/working")
+    else:
+        sim_ws = test.workspace
+    sim = flopy.mf6.MFSimulation(
+        sim_name=name,
+        sim_ws=str(sim_ws),
+        exe_name="mf6",
+    )
+    flopy.mf6.ModflowTdis(sim, nper=nper)
+    linear_acceleration = "bicgstab"
+    newtonoptions = "newton under_relaxation"
+
+    flopy.mf6.ModflowIms(
+        sim,
+        print_option="ALL",
+        linear_acceleration=linear_acceleration,
+        outer_maximum=nouter,
+        outer_dvclose=hclose_outer,
+        inner_maximum=ninner,
+        inner_dvclose=hclose,
+        rcloserecord=rclose,
+    )
+    gwf = flopy.mf6.ModflowGwf(
+        sim,
+        modelname=name,
+        newtonoptions=newtonoptions,
+    )
+    flopy.mf6.ModflowGwfdis(
+        gwf,
+        nlay=nlay,
+        nrow=nrow,
+        ncol=ncol,
+        delr=delr,
+        delc=delc,
+        top=top,
+        botm=botm,
+        idomain=1,
+    )
+    flopy.mf6.ModflowGwfnpf(
+        gwf,
+        icelltype=1,
+        k=k11,
+    )
+    flopy.mf6.ModflowGwfic(gwf, strt=H1)
+    flopy.mf6.ModflowGwfchd(gwf, stress_period_data=chd_spd)
+
+    head_filerecord = f"{name}.hds"
+    flopy.mf6.ModflowGwfoc(
+        gwf,
+        head_filerecord=head_filerecord,
+        saverecord=[("HEAD", "ALL")],
+    )
+
+    if idx == 1:
+        sim.write_simulation(silent=True)
+        mfsplit = flopy.mf6.utils.Mf6Splitter(sim)
+        split_array = np.tri(nrow, ncol).astype(int)
+        new_sim = mfsplit.split_model(split_array)
+        new_sim.set_sim_path(test.workspace)
+        mfsplit.save_node_mapping(pl.Path(f"{test.workspace}/mapping.json"))
+        return new_sim, None
+    else:
+        return sim, None
+
+
+def check_output(idx, test):
+    mf6sim = flopy.mf6.MFSimulation.load(sim_ws=test.workspace)
+    if idx == 1:
+        mfsplit = flopy.mf6.utils.Mf6Splitter(mf6sim)
+        mfsplit.load_node_mapping(
+            mf6sim, pl.Path(f"{test.workspace}/mapping.json")
+        )
+        head_dict = {}
+        for modelname in mf6sim.model_names:
+            mnum = int(modelname.split("_")[-1])
+            head_dict[mnum] = (
+                mf6sim.get_model(modelname).output.head().get_data()
+            )
+        heads = mfsplit.reconstruct_array(head_dict)
+    else:
+        heads = mf6sim.get_model().output.head().get_data()
+    msg = "head comparison failed"
+    assert np.allclose(base_heads, heads), msg
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+    )
+    test.run()
diff --git a/autotest/test_gwf_noptc01.py b/autotest/test_gwf_noptc01.py
index d32c04fdecb..19be84d2512 100644
--- a/autotest/test_gwf_noptc01.py
+++ b/autotest/test_gwf_noptc01.py
@@ -2,12 +2,12 @@
 
 import flopy
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["gwf_noptc01", "gwf_noptc02", "gwf_noptc03"]
+cases = ["gwf_noptc01", "gwf_noptc02", "gwf_noptc03"]
 no_ptcrecords = ["FIRST", "ALL", None]
-htol = [None for idx in range(len(ex))]
+htol = [None for _ in range(len(cases))]
 
 # static model data
 # temporal discretization
@@ -49,7 +49,7 @@
 
 
 def get_model(idx, dir, no_ptcrecord):
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
     ws = dir
@@ -123,22 +123,22 @@ def get_model(idx, dir, no_ptcrecord):
 
 
 # water table recharge problem
-def build_model(idx, dir):
-    sim = get_model(idx, dir, no_ptcrecords[idx])
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace, no_ptcrecords[idx])
 
     # build MODFLOW-6 without no_ptc option
-    pth = os.path.join(dir, "mf6")
+    pth = os.path.join(test.workspace, "mf6")
     mc = get_model(idx, pth, None)
 
     return sim, mc
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(TestSimulation(name=name, exe_dict=targets, idxsim=idx), ws)
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+    )
+    test.run()
diff --git a/autotest/test_gwf_npf01_75x75.py b/autotest/test_gwf_npf01_75x75.py
index e976784b582..505059079ed 100644
--- a/autotest/test_gwf_npf01_75x75.py
+++ b/autotest/test_gwf_npf01_75x75.py
@@ -3,17 +3,17 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["npf01a_75x75", "npf01b_75x75"]
+cases = ["npf01a_75x75", "npf01b_75x75"]
 top = [100.0, 0.0]
 laytyp = [1, 0]
 ss = [0.0, 1.0e-4]
 sy = [0.1, 0.0]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 75, 75
     nper = 3
     perlen = [1.0, 1000.0, 1.0]
@@ -54,10 +54,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -132,7 +132,7 @@ def build_model(idx, dir):
         gwf,
         print_input=True,
         print_flows=True,
-        maxbound=len(ws),
+        maxbound=len(str(ws)),
         stress_period_data=wd6,
         save_flows=False,
     )
@@ -148,8 +148,8 @@ def build_model(idx, dir):
     )
 
     # build MODFLOW-2005 files
-    ws = os.path.join(dir, "mf2005")
-    mc = flopy.modflow.Modflow(name, model_ws=ws)
+    ws = os.path.join(test.workspace, "mf2005")
+    mc = flopy.modflow.Modflow(name, model_ws=ws, exe_name=test.targets["mf2005"])
     dis = flopy.modflow.ModflowDis(
         mc,
         nlay=nlay,
@@ -190,12 +190,12 @@ def build_model(idx, dir):
     return sim, mc
 
 
-# - No need to change any code below
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(TestSimulation(name=name, exe_dict=targets), str(function_tmpdir))
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+    )
+    test.run()
diff --git a/autotest/test_gwf_npf02_rewet.py b/autotest/test_gwf_npf02_rewet.py
index 96eb0e8d4ab..ad448eb8e24 100644
--- a/autotest/test_gwf_npf02_rewet.py
+++ b/autotest/test_gwf_npf02_rewet.py
@@ -3,10 +3,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["npf02_hreweta", "npf02_hrewetb", "npf02_hrewetc", "npf02_hrewetd"]
+cases = ["npf02_hreweta", "npf02_hrewetb", "npf02_hrewetc", "npf02_hrewetd"]
 ncols = [[15], [10, 5], [15], [10, 5]]
 nlays = [1, 1, 3, 3]
 
@@ -50,8 +50,8 @@ def get_local_data(idx):
     return ncolst, nmodels, mnames
 
 
-def build_model(idx, dir):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
     nlay = nlays[idx]
 
     if nlay == 1:
@@ -80,7 +80,7 @@ def build_model(idx, dir):
     cd6left[1] = c6left
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -207,9 +207,7 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_hds(sim):
-    print("evaluating rewet heads...")
-
+def check_output(idx, test):
     hdata01lay = [
         [
             1.000000000000000000e02,
@@ -283,7 +281,6 @@ def eval_hds(sim):
         ],
     ]
 
-    idx = sim.idxsim
     ncolst, nmodels, mnames = get_local_data(idx)
     nlay = nlays[idx]
 
@@ -295,7 +292,7 @@ def eval_hds(sim):
     imid = int(nrow / 2)
 
     for j in range(nmodels):
-        fn = os.path.join(sim.simpath, f"{mnames[j]}.hds")
+        fn = os.path.join(test.workspace, f"{mnames[j]}.hds")
         hobj = flopy.utils.HeadFile(fn)
         times = hobj.get_times()
         ioff = 0
@@ -313,7 +310,7 @@ def eval_hds(sim):
             hval[n, ioff:i1] = ht.copy()
 
     # # save results if the know results change slightly
-    # fpth = os.path.join(sim.simpath, "results.dat")
+    # fpth = os.path.join(sim.workspace, "results.dat")
     # np.savetxt(fpth, hval, delimiter=",")
 
     # known results
@@ -329,25 +326,21 @@ def eval_hds(sim):
     msg = f"maximum absolute maw head difference ({diffmax}) "
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_hds, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_npf03_sfr.py b/autotest/test_gwf_npf03_sfr.py
index d4490ea4146..3e19037b510 100644
--- a/autotest/test_gwf_npf03_sfr.py
+++ b/autotest/test_gwf_npf03_sfr.py
@@ -3,11 +3,11 @@
 import flopy
 import numpy as np
 import pytest
+
 from conftest import project_root_path
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["npf03_sfra", "npf03_sfrb"]
+cases = ["npf03_sfra", "npf03_sfrb"]
 fpth = str(project_root_path / "autotest" / "data" / "npf03_hk.ref")
 shape = (50, 108)
 hk = flopy.utils.Util2d.load_txt(shape, fpth, dtype=float, fmtin="(FREE)")
@@ -30,7 +30,8 @@
 hbndl = [12.0, 8.0]
 
 # sfr data
-unit_conv = 1.0
+len_conv = 1.0
+time_conv = 1.0
 slope = 1.2012012e-03
 width = 20.0
 bthick = 1.5
@@ -54,8 +55,8 @@ def get_local_data(idx):
     return ncolst, nmodels, mnames
 
 
-def build_model(idx, dir):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
 
     # set local data for this model
     ncolst, nmodels, mnames = get_local_data(idx)
@@ -72,7 +73,7 @@ def build_model(idx, dir):
     cd6right = {0: c6right}
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name,
         memory_print_option="all",
@@ -270,7 +271,8 @@ def build_model(idx, dir):
 
         sfr = flopy.mf6.ModflowGwfsfr(
             gwf,
-            unit_conversion=unit_conv,
+            length_conversion=len_conv,
+            time_conversion=time_conv,
             print_stage=True,
             print_flows=True,
             package_convergence_filerecord=cnvgpth,
@@ -334,9 +336,7 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_hds(sim):
-    print("evaluating mover test heads...")
-
+def check_output(idx, test):
     hdata = np.array(
         [
             1.200000000000000000e01,
@@ -5743,7 +5743,6 @@ def eval_hds(sim):
     )
     hdata = hdata.reshape((1, 50, 108))
 
-    idx = sim.idxsim
     ncolst, nmodels, mnames = get_local_data(idx)
 
     # make single head array
@@ -5754,7 +5753,7 @@ def eval_hds(sim):
 
     i0 = 0
     for j in range(nmodels):
-        fn = os.path.join(sim.simpath, f"{mnames[j]}.hds")
+        fn = os.path.join(test.workspace, f"{mnames[j]}.hds")
         hobj = flopy.utils.HeadFile(fn)
         h = hobj.get_data()
         i1 = i0 + h.shape[2]
@@ -5768,26 +5767,22 @@ def eval_hds(sim):
     msg = f"maximum absolute maw head difference ({diffmax}) "
 
     if diffmax > dtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_hds, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_npf04_spdis.py b/autotest/test_gwf_npf04_spdis.py
index b771b1b4161..22577cccb91 100644
--- a/autotest/test_gwf_npf04_spdis.py
+++ b/autotest/test_gwf_npf04_spdis.py
@@ -1,11 +1,9 @@
 """
-MODFLOW 6 Autotest
 Test the specific discharge calculation for an LGR-like simulation that has
 a parent model and a child model.  The child model is inset into the parent
 model, but they both have the same resolution, so it is essentially a simple
 3D grid.  The child qx velocity should be the same as the qx velocity in
 the parent grid.  The heads are also compared.
-
 """
 
 import os
@@ -14,16 +12,15 @@
 import numpy as np
 import pytest
 from flopy.utils.lgrutil import Lgr
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["npf04"]
+cases = ["npf04"]
 namea = "a"
 nameb = "b"
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     # grid properties
     nlay = 3
     nrow = 6
@@ -46,12 +43,12 @@ def build_model(idx, dir):
     ncppl = [1, 1, 1]
     lgr = Lgr(nlay, nrow, ncol, delr, delc, top, botm, idomain, ncpp, ncppl)
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
     # create simulation
     sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name="mf6", sim_ws=dir
+        sim_name=name, version="mf6", exe_name="mf6", sim_ws=test.workspace
     )
 
     # create tdis package
@@ -175,14 +172,12 @@ def qxqyqz(fname, nlay, nrow, ncol):
     return qx, qy, qz
 
 
-def eval_mf6(sim):
-    print("evaluating head and qx in parent and child models...")
-
+def check_output(idx, test):
     # make sure parent head is same as child head in same column
-    fname = os.path.join(sim.simpath, f"{namea}.hds")
+    fname = os.path.join(test.workspace, f"{namea}.hds")
     hdobj = flopy.utils.HeadFile(fname)
     ha = hdobj.get_data()
-    fname = os.path.join(sim.simpath, f"{nameb}.hds")
+    fname = os.path.join(test.workspace, f"{nameb}.hds")
     hdobj = flopy.utils.HeadFile(fname)
     hb = hdobj.get_data()
     msg = f"Heads should be the same {ha[0, 1, 2]} {hb[0, 0, 0]}"
@@ -190,17 +185,17 @@ def eval_mf6(sim):
 
     # make sure specific discharge is calculated correctly for child and
     # parent models (even though child model has same resolution as parent
-    fname = os.path.join(sim.simpath, f"{namea}.cbc")
+    fname = os.path.join(test.workspace, f"{namea}.cbc")
     nlaya, nrowa, ncola = ha.shape
     qxa, qya, qza = qxqyqz(fname, nlaya, nrowa, ncola)
-    fname = os.path.join(sim.simpath, f"{nameb}.cbc")
+    fname = os.path.join(test.workspace, f"{nameb}.cbc")
     nlayb, nrowb, ncolb = hb.shape
     qxb, qyb, qzb = qxqyqz(fname, nlayb, nrowb, ncolb)
     msg = f"qx should be the same {qxa[0, 2, 1]} {qxb[0, 0, 0]}"
     assert np.allclose(qxa[0, 2, 1], qxb[0, 0, 0]), msg
 
-    cbcpth = os.path.join(sim.simpath, f"{namea}.cbc")
-    grdpth = os.path.join(sim.simpath, f"{namea}.dis.grb")
+    cbcpth = os.path.join(test.workspace, f"{namea}.cbc")
+    grdpth = os.path.join(test.workspace, f"{namea}.dis.grb")
     grb = flopy.mf6.utils.MfGrdFile(grdpth)
     cbb = flopy.utils.CellBudgetFile(cbcpth, precision="double")
     flow_ja_face = cbb.get_data(text="FLOW-JA-FACE")
@@ -212,17 +207,13 @@ def eval_mf6(sim):
         assert np.allclose(res, 0.0, atol=1.0e-6), errmsg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_mf6, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_npf05_anisotropy.py b/autotest/test_gwf_npf05_anisotropy.py
index cb6e46e0272..221c086f41c 100644
--- a/autotest/test_gwf_npf05_anisotropy.py
+++ b/autotest/test_gwf_npf05_anisotropy.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 Test to make sure that NPF anisotropy ratio options are read and processed
 correctly.
 """
@@ -9,14 +8,13 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["npf05a"]
+from framework import TestFramework
 
+cases = ["npf05a"]
 
-def build_model(idx, dir):
 
+def build_models(idx, test):
     nlay, nrow, ncol = 2, 1, 5
     chdheads = [100.0]
     nper = len(chdheads)
@@ -37,7 +35,7 @@ def build_model(idx, dir):
     name = "npf"
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -125,9 +123,8 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-    fpth = os.path.join(sim.simpath, "npf.hds")
+def check_output(idx, test):
+    fpth = os.path.join(test.workspace, "npf.hds")
     hobj = flopy.utils.HeadFile(fpth, precision="double")
     heads = hobj.get_alldata()
     # answer was obtained from running problem without anistropy
@@ -147,17 +144,13 @@ def eval_model(sim):
     assert np.allclose(heads.flatten(), answer)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_npf_thickstrt.py b/autotest/test_gwf_npf_thickstrt.py
index be92018ad1d..28d6362a48e 100644
--- a/autotest/test_gwf_npf_thickstrt.py
+++ b/autotest/test_gwf_npf_thickstrt.py
@@ -3,10 +3,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = [
+cases = [
     "gwf_npf_thickstrt01",  # case 01 -- icelltype=0
     "gwf_npf_thickstrt02",  # case 02 -- icelltype=0, using thickstrt, but it has no effect
     "gwf_npf_thickstrt03",  # case 03 -- icelltype=-1, using thickstrt and strt = 5.
@@ -21,7 +21,8 @@
 icelltype = [0, 0, -1, 1, -1, 0, -1, 1, -1]
 hfb_on = [False, False, False, False, False, True, True, True, True]
 
-def build_model(idx, dir):
+
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 6
     nper = 1
     perlen = [1.0]
@@ -46,7 +47,7 @@ def build_model(idx, dir):
     name = "flow"
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -101,11 +102,7 @@ def build_model(idx, dir):
     thickstrt_option = thickstrt[idx]
     ict = icelltype[idx]
     npf = flopy.mf6.ModflowGwfnpf(
-        gwf, 
-        thickstrt=thickstrt_option,
-        icelltype=ict, 
-        k=hk, 
-        k33=hk
+        gwf, thickstrt=thickstrt_option, icelltype=ict, k=hk, k33=hk
     )
 
     if hfb_on[idx]:
@@ -113,7 +110,7 @@ def build_model(idx, dir):
             gwf,
             print_input=True,
             maxhfb=1,
-            stress_period_data=[((0, 0, 2), (0, 0, 3), 1.e-4)],
+            stress_period_data=[((0, 0, 2), (0, 0, 3), 1.0e-4)],
         )
 
     # chd files
@@ -139,12 +136,10 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
+def check_output(idx, test):
     name = "flow"
 
-    fpth = os.path.join(sim.simpath, f"{name}.hds")
+    fpth = os.path.join(test.workspace, f"{name}.hds")
     hobj = flopy.utils.HeadFile(fpth, precision="double")
     head = hobj.get_data().flatten()
 
@@ -157,60 +152,70 @@ def eval_model(sim):
     answer_confined_hfb = (6.0, 5.9998, 5.9996, 4.0004, 4.0002, 4.0)
     answer_confined_hfb = np.array(answer_confined_hfb)
 
-    answer_confined_thickstart_hfb = (6., 5.9996004, 5.9992008, 4.0007992, 4.0003996, 4.)
+    answer_confined_thickstart_hfb = (
+        6.0,
+        5.9996004,
+        5.9992008,
+        4.0007992,
+        4.0003996,
+        4.0,
+    )
     answer_confined_thickstart_hfb = np.array(answer_confined_thickstart_hfb)
 
-    answer_unconfined_hfb = (6., 5.99983342, 5.99966683, 4.00049971, 4.00024986, 4.)
+    answer_unconfined_hfb = (
+        6.0,
+        5.99983342,
+        5.99966683,
+        4.00049971,
+        4.00024986,
+        4.0,
+    )
     answer_unconfined_hfb = np.array(answer_unconfined_hfb)
 
     answer_dict = {
-        0: answer_linear, 
-        1: answer_linear, 
-        2: answer_linear, 
-        3: answer_water_table, 
-        4: answer_water_table, 
+        0: answer_linear,
+        1: answer_linear,
+        2: answer_linear,
+        3: answer_water_table,
+        4: answer_water_table,
         5: answer_confined_hfb,
         6: answer_confined_thickstart_hfb,
         7: answer_unconfined_hfb,
         8: answer_unconfined_hfb,
     }
 
-    hres = answer_dict[sim.idxsim]
+    hres = answer_dict[idx]
     assert np.allclose(
         hres, head
     ), "simulated head do not match with known solution."
 
-    fpth = os.path.join(sim.simpath, f"{name}.cbc")
+    fpth = os.path.join(test.workspace, f"{name}.cbc")
     cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
-    q_simulated_inflow = cobj.get_data(idx=1)[0]['q'][0]
+    q_simulated_inflow = cobj.get_data(idx=1)[0]["q"][0]
     q_answer_dict = {
-        0: 4.,
-        1: 4.,
-        2: 2.,
+        0: 4.0,
+        1: 4.0,
+        2: 2.0,
         3: 1.9965396769631871,
         4: 1.9965396769631871,
-        5: 1.9990E-03,
-        6: 1.9980E-03,
-        7: 9.9949E-04,
-        8: 9.9949E-04,
+        5: 1.9990e-03,
+        6: 1.9980e-03,
+        7: 9.9949e-04,
+        8: 9.9949e-04,
     }
-    q_answer = q_answer_dict[sim.idxsim]
+    q_answer = q_answer_dict[idx]
     assert np.allclose(
         q_answer, q_simulated_inflow
     ), "simulated flow does not match with known solution."
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_npf_tvk01.py b/autotest/test_gwf_npf_tvk01.py
index f7791a3c6cc..530da8314c4 100644
--- a/autotest/test_gwf_npf_tvk01.py
+++ b/autotest/test_gwf_npf_tvk01.py
@@ -3,14 +3,14 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["tvk01"]
+cases = ["tvk01"]
 time_varying_k = [1.0, 10.0]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 3, 3, 3
     perlen = [100.0, 100.0]
     nper = len(perlen)
@@ -31,10 +31,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -138,13 +138,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
-    gwfname = "gwf_" + sim.name
+def check_output(idx, test):
+    gwfname = "gwf_" + test.name
 
     # head
-    fpth = os.path.join(sim.simpath, f"{gwfname}.hds")
+    fpth = os.path.join(test.workspace, f"{gwfname}.hds")
     try:
         hobj = flopy.utils.HeadFile(fpth, precision="double")
         head = hobj.get_data()
@@ -152,7 +150,7 @@ def eval_model(sim):
         assert False, f'could not load data from "{fpth}"'
 
     # budget
-    fpth = os.path.join(sim.simpath, f"{gwfname}.cbc")
+    fpth = os.path.join(test.workspace, f"{gwfname}.cbc")
     try:
         bobj = flopy.utils.CellBudgetFile(fpth, precision="double")
         bud_allspd = bobj.get_data(text="CHD")
@@ -172,24 +170,18 @@ def eval_model(sim):
         print(f"Calculated q is {flow_rate_calc}")
         for node, node2, q in bud:
             print(node, node2, q, flow_rate_calc)
-            errmsg = f"Expected flow rate {flow_rate_calc} but found {q}"
-            assert np.isclose(flow_rate_calc, abs(q))
-
-    # comment when done testing
-    # assert False
-
-
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=0
-        ),
-        ws,
+            assert np.isclose(
+                flow_rate_calc, abs(q)
+            ), f"Expected flow rate {flow_rate_calc} but found {q}"
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_npf_tvk02.py b/autotest/test_gwf_npf_tvk02.py
index 48d30e65a0d..d0f36cdc7e2 100644
--- a/autotest/test_gwf_npf_tvk02.py
+++ b/autotest/test_gwf_npf_tvk02.py
@@ -3,13 +3,13 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["tvk02"]
+cases = ["tvk02"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 3
     perlen = [1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0]
     nper = len(perlen)
@@ -32,10 +32,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -158,13 +158,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
-    gwfname = "gwf_" + sim.name
+def check_output(idx, test):
+    gwfname = "gwf_" + test.name
 
     # head
-    fpth = os.path.join(sim.simpath, f"{gwfname}.hds")
+    fpth = os.path.join(test.workspace, f"{gwfname}.hds")
     try:
         hobj = flopy.utils.HeadFile(fpth, precision="double")
         head = hobj.get_alldata()
@@ -193,29 +191,19 @@ def eval_model(sim):
 
     for kper, expected_result in enumerate(expected_results):
         h = head[kper, ex_lay - 1, ex_row - 1, ex_col - 1]
-
         print(kper, h, expected_result)
-
-        errmsg = (
-            f"Expected head {expected_result} in period {kper} but found {h}"
-        )
-        assert np.isclose(h, expected_result)
-
-    # comment when done testing
-    # assert False
-
-
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=0
-        ),
-        ws,
+        assert np.isclose(
+            h, expected_result
+        ), f"Expected head {expected_result} in period {kper} but found {h}"
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_npf_tvk03.py b/autotest/test_gwf_npf_tvk03.py
index 226ee8bc932..99bb445f171 100644
--- a/autotest/test_gwf_npf_tvk03.py
+++ b/autotest/test_gwf_npf_tvk03.py
@@ -3,13 +3,13 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["tvk03"]
+cases = ["tvk03"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 3, 1, 1
     perlen = [1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0]
     nper = len(perlen)
@@ -32,10 +32,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -158,13 +158,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
-    gwfname = "gwf_" + sim.name
+def check_output(idx, test):
+    gwfname = "gwf_" + test.name
 
     # head
-    fpth = os.path.join(sim.simpath, f"{gwfname}.hds")
+    fpth = os.path.join(test.workspace, f"{gwfname}.hds")
     try:
         hobj = flopy.utils.HeadFile(fpth, precision="double")
         head = hobj.get_alldata()
@@ -193,29 +191,19 @@ def eval_model(sim):
 
     for kper, expected_result in enumerate(expected_results):
         h = head[kper, ex_lay - 1, ex_row - 1, ex_col - 1]
-
         print(kper, h, expected_result)
-
-        errmsg = (
-            f"Expected head {expected_result} in period {kper} but found {h}"
-        )
-        assert np.isclose(h, expected_result)
-
-    # comment when done testing
-    # assert False
-
-
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=0
-        ),
-        ws,
+        assert np.isclose(
+            h, expected_result
+        ), f"Expected head {expected_result} in period {kper} but found {h}"
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_npf_tvk04.py b/autotest/test_gwf_npf_tvk04.py
index 67b3c980c33..5168b42a643 100644
--- a/autotest/test_gwf_npf_tvk04.py
+++ b/autotest/test_gwf_npf_tvk04.py
@@ -3,14 +3,14 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["tvk05"]
+cases = ["tvk05"]
 time_varying_k = [1.0, 10.0]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 3, 3, 3
     perlen = [100.0, 100.0]
     nper = len(perlen)
@@ -32,10 +32,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -155,13 +155,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
+def check_output(idx, test):
     # budget
     try:
-        fname = f"gwf_{sim.name}.lst"
-        ws = sim.simpath
+        fname = f"gwf_{test.name}.lst"
+        ws = test.workspace
         fname = os.path.join(ws, fname)
         lst = flopy.utils.Mf6ListBudget(
             fname, budgetkey="VOLUME BUDGET FOR ENTIRE MODEL"
@@ -184,17 +182,13 @@ def eval_model(sim):
     assert 2.0 * sp_x[0][8] < sp_x[1][8], errmsg
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_npf_tvk05.py b/autotest/test_gwf_npf_tvk05.py
index 99059f5d9f0..d0347b7f913 100644
--- a/autotest/test_gwf_npf_tvk05.py
+++ b/autotest/test_gwf_npf_tvk05.py
@@ -3,14 +3,14 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["tvk05"]
+cases = ["tvk05"]
 time_varying_k = [1.0, 10.0]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 3, 3
     perlen = [100.0, 100.0]
     nper = len(perlen)
@@ -32,10 +32,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -156,13 +156,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
+def check_output(idx, test):
     # budget
     try:
-        fname = f"gwf_{sim.name}.lst"
-        ws = sim.simpath
+        fname = f"gwf_{test.name}.lst"
+        ws = test.workspace
         fname = os.path.join(ws, fname)
         lst = flopy.utils.Mf6ListBudget(
             fname, budgetkey="VOLUME BUDGET FOR ENTIRE MODEL"
@@ -185,17 +183,13 @@ def eval_model(sim):
     assert sp_x[0][8] == sp_x[1][8], errmsg
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_obs01.py b/autotest/test_gwf_obs01.py
index bcee2743b56..ac69e386f3d 100644
--- a/autotest/test_gwf_obs01.py
+++ b/autotest/test_gwf_obs01.py
@@ -3,11 +3,13 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
 cell_dimensions = (300,)
-ex = [f"gwf_obs01{chr(ord('a') + idx)}" for idx in range(len(cell_dimensions))]
+cases = [
+    f"gwf_obs01{chr(ord('a') + idx)}" for idx in range(len(cell_dimensions))
+]
 h0, h1 = 1.0, 0.0
 
 
@@ -23,11 +25,11 @@ def get_obs(idx):
         for j in range(ncol):
             node = i * ncol + j + 1
             obs_lst.append([node, "head", (0, i, j)])
-    return {f"{ex[idx]}.gwf.obs.csv": obs_lst}
+    return {f"{cases[idx]}.gwf.obs.csv": obs_lst}
 
 
-def get_obs_out(sim):
-    fpth = os.path.join(sim.simpath, f"{ex[sim.idxsim]}.gwf.obs.csv")
+def get_obs_out(idx, test):
+    fpth = os.path.join(test.workspace, f"{cases[idx]}.gwf.obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
         return tc.view((float, len(tc.dtype.names)))[1:]
@@ -42,7 +44,7 @@ def get_chd(idx):
     return {0: c}
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, cell_dimensions[idx], cell_dimensions[idx]
     nper = 1
     perlen = [5.0]
@@ -62,10 +64,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -136,26 +138,22 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model observations...")
-    hres = get_strt_array(sim.idxsim).flatten()
-    obs = get_obs_out(sim)
-    msg = "simulated head observations do not match with known solution."
-    assert np.allclose(hres, obs), msg
+def check_output(idx, test):
+    hres = get_strt_array(idx).flatten()
+    obs = get_obs_out(idx, test)
+    assert np.allclose(
+        hres, obs
+    ), "simulated head observations do not match with known solution."
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_obs02.py b/autotest/test_gwf_obs02.py
index bfef5b1a50e..4af6330f91a 100644
--- a/autotest/test_gwf_obs02.py
+++ b/autotest/test_gwf_obs02.py
@@ -7,16 +7,16 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
 cell_dimensions = (300,)
-ex = ["gwf_obs02"]
+cases = ["gwf_obs02"]
 h0, h1 = 1.0, 0.0
 nlay, nrow, ncol = 1, 10, 10
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nper = 1
     perlen = [5.0]
     nstp = [1]
@@ -35,10 +35,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -124,13 +124,12 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model observations...")
+def check_output(idx, test):
     headcsv = np.empty((nlay, nrow, ncol), dtype=float)
     for i in range(nrow):
-        fname = f"{sim.name}.{i}.obs.csv"
+        fname = f"{test.name}.{i}.obs.csv"
         print(f"Loading and testing {fname}")
-        fname = os.path.join(sim.simpath, fname)
+        fname = os.path.join(test.workspace, fname)
         rec = np.genfromtxt(fname, names=True, delimiter=",", deletechars="")
         for j in range(ncol):
             obsname_true = f"h_{i}_{j}".upper()
@@ -142,7 +141,7 @@ def eval_model(sim):
             assert obsname_true == obsname_found, errmsg
         headcsv[0, i, :] = np.array(rec.tolist()[1:])
 
-    fn = os.path.join(sim.simpath, f"{sim.name}.hds")
+    fn = os.path.join(test.workspace, f"{test.name}.hds")
     hobj = flopy.utils.HeadFile(fn)
     headbin = hobj.get_data()
 
@@ -151,17 +150,13 @@ def eval_model(sim):
     ), "headcsv not equal head from binary file"
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_pertim.py b/autotest/test_gwf_pertim.py
index d3adcccc358..0e02c57ed43 100644
--- a/autotest/test_gwf_pertim.py
+++ b/autotest/test_gwf_pertim.py
@@ -3,10 +3,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = [
+cases = [
     "gwf_pertim",
 ]
 
@@ -17,8 +17,8 @@
 nstp = [1]
 tsmult = [1.0]
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 # spatial discretization data
 nlay, nrow, ncol = 3, 21, 20
@@ -38,11 +38,11 @@
 river_spd = [(0, i, ncol - 1, 320.0, "river") for i in range(nrow)]
 
 
-def build_model(idx, dir):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -114,11 +114,8 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-
-    print("evaluating results...")
-
-    fpth = os.path.join(sim.simpath, f"{sim.name}.lst")
+def check_output(idx, test):
+    fpth = os.path.join(test.workspace, f"{test.name}.lst")
     mflist = flopy.utils.Mf6ListBudget(fpth)
     inc = mflist.get_incremental()
 
@@ -133,20 +130,13 @@ def eval_model(sim):
     ), f"CHD2_OUT <> {q_out} ({q_out_sim})"
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_model,
-            idxsim=idx,
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_ptc01.py b/autotest/test_gwf_ptc01.py
index cf1737c3020..2e58b9c14da 100644
--- a/autotest/test_gwf_ptc01.py
+++ b/autotest/test_gwf_ptc01.py
@@ -8,13 +8,11 @@
 import os
 
 import flopy
-import numpy as np
 import pytest
-from conftest import project_root_path
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["ptc01"]
+cases = ["ptc01"]
 # static model data
 # temporal discretization
 nper = 1
@@ -57,7 +55,7 @@
 
 
 def build_mf6(idx, ws, storage=True):
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
     sim = flopy.mf6.MFSimulation(
@@ -128,28 +126,24 @@ def build_mf6(idx, ws, storage=True):
         saverecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
         printrecord=[("HEAD", "LAST"), ("BUDGET", "ALL")],
     )
-    
+
     return sim
 
 
-def build_model(idx, dir):
-    ws = dir
+def build_models(idx, test):
     # build mf6 with storage package but steady state stress periods
-    sim = build_mf6(idx, ws, storage=True)
-
+    sim = build_mf6(idx, test.workspace, storage=True)
     # build mf6 with no storage package
-    wsc = os.path.join(ws, "mf6")
-    mc = build_mf6(idx, wsc, storage=False)
-
+    mc = build_mf6(idx, os.path.join(test.workspace, "mf6"), storage=False)
     return sim, mc
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(TestSimulation(name=name, exe_dict=targets), ws)
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        targets=targets,
+    )
+    test.run()
diff --git a/autotest/test_gwf_rch01.py b/autotest/test_gwf_rch01.py
index 879739313f5..c3c1947538b 100644
--- a/autotest/test_gwf_rch01.py
+++ b/autotest/test_gwf_rch01.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 Test to make sure that recharge is passed to the highest active layer and
 verify that recharge is in the highest active layer by looking at the
 individual budget terms.  For this test, there are two layers and five
@@ -13,15 +12,14 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["rch01a", "rch01b", "rch01c"]
+cases = ["rch01a", "rch01b", "rch01c"]
 irch = [None, 0, [1, 1, 0, 1, 1]]
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     nlay, nrow, ncol = 2, 1, 5
     chdheads = [25.0]
     nper = len(chdheads)
@@ -43,7 +41,7 @@ def build_model(idx, dir):
     name = "rch"
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -121,10 +119,8 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
-    fpth = os.path.join(sim.simpath, "rch.cbc")
+def check_output(idx, test):
+    fpth = os.path.join(test.workspace, "rch.cbc")
     bobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     records = bobj.get_data(text="rch")[0]
 
@@ -136,22 +132,18 @@ def eval_model(sim):
     assert np.allclose(records["node2"], answer["node2"])
     assert np.allclose(records["q"], answer["q"])
 
-    fpth = os.path.join(sim.simpath, "rch.hds")
+    fpth = os.path.join(test.workspace, "rch.hds")
     hobj = flopy.utils.HeadFile(fpth, precision="double")
     heads = hobj.get_alldata()
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_rch02.py b/autotest/test_gwf_rch02.py
index e7aced8d6ff..3decd75cb36 100644
--- a/autotest/test_gwf_rch02.py
+++ b/autotest/test_gwf_rch02.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 Test to make sure that array based recharge is applied correctly when idomain
 is used to remove part of the grid.
 """
@@ -9,14 +8,13 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["rch02"]
+from framework import TestFramework
 
+cases = ["rch02"]
 
-def build_model(idx, dir):
 
+def build_models(idx, test):
     nlay, nrow, ncol = 2, 4, 5
     perlen = [1.0]
     nper = len(perlen)
@@ -35,7 +33,7 @@ def build_model(idx, dir):
     name = "rch"
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -110,10 +108,8 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
-    fpth = os.path.join(sim.simpath, "rch.cbc")
+def check_output(idx, test):
+    fpth = os.path.join(test.workspace, "rch.cbc")
     bobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     records = bobj.get_data(text="rch")[0]
 
@@ -128,22 +124,18 @@ def eval_model(sim):
     errmsg = "node2 numbers must be the same as node."
     assert np.allclose(records["node2"], records["node"]), errmsg
 
-    fpth = os.path.join(sim.simpath, "rch.hds")
+    fpth = os.path.join(test.workspace, "rch.hds")
     hobj = flopy.utils.HeadFile(fpth, precision="double")
     heads = hobj.get_alldata()
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_rch03.py b/autotest/test_gwf_rch03.py
index c853cd4eaef..e8e608e407c 100644
--- a/autotest/test_gwf_rch03.py
+++ b/autotest/test_gwf_rch03.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 Test to make sure that array based recharge is applied correctly when idomain
 is used with -1, 0, and 1 for top layer.
 """
@@ -9,14 +8,13 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["rch03"]
+from framework import TestFramework
 
+cases = ["rch03"]
 
-def build_model(idx, dir):
 
+def build_models(idx, test):
     nlay, nrow, ncol = 2, 4, 5
     perlen = [1.0]
     nper = len(perlen)
@@ -35,7 +33,7 @@ def build_model(idx, dir):
     name = "rch"
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -132,10 +130,8 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
-    fpth = os.path.join(sim.simpath, "rch.cbc")
+def check_output(idx, test):
+    fpth = os.path.join(test.workspace, "rch.cbc")
     bobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     records = bobj.get_data(text="rch")[0]
 
@@ -154,22 +150,18 @@ def eval_model(sim):
     errmsg = f"rech q must be {answer}.  found {records['q']}"
     assert np.allclose(records["q"], answer), errmsg
 
-    fpth = os.path.join(sim.simpath, "rch.hds")
+    fpth = os.path.join(test.workspace, "rch.hds")
     hobj = flopy.utils.HeadFile(fpth, precision="double")
     heads = hobj.get_alldata()
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_returncodes.py b/autotest/test_gwf_returncodes.py
index 3eda6b7ef76..67aa6f44eb0 100644
--- a/autotest/test_gwf_returncodes.py
+++ b/autotest/test_gwf_returncodes.py
@@ -271,5 +271,5 @@ def compiler_argv(dir, exe):
     ),
 )
 def test_main(fn, function_tmpdir, targets):
-    mf6 = targets.as_dict()["mf6"]
+    mf6 = targets["mf6"]
     eval(fn)(function_tmpdir, mf6)
diff --git a/autotest/test_gwf_sfr_badfactor.py b/autotest/test_gwf_sfr_badfactor.py
index 23677308164..f55eb08bc4d 100644
--- a/autotest/test_gwf_sfr_badfactor.py
+++ b/autotest/test_gwf_sfr_badfactor.py
@@ -1,16 +1,19 @@
 import flopy
 import numpy as np
+import pytest
+
+from framework import TestFramework
 
 paktest = "sfr"
-testname = "ts_sfr01"
+cases = ["ts_sfr01"]
 
 
-def build_model(ws, exe, timeseries=False):
+def build_models(idx, test, timeseries=False):
     # static model data
     # temporal discretization
     nper = 1
     tdis_rc = []
-    for idx in range(nper):
+    for _ in range(nper):
         tdis_rc.append((1.0, 1, 1.0))
     ts_times = np.arange(0.0, 2.0, 1.0, dtype=float)
 
@@ -34,9 +37,9 @@ def build_model(ws, exe, timeseries=False):
     imsla = "BICGSTAB"
 
     # build MODFLOW 6 files
-    name = testname
+    name = cases[idx]
     sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name=exe, sim_ws=ws
+        sim_name=name, version="mf6", exe_name="mf6", sim_ws=test.workspace
     )
     # create tdis package
     tdis = flopy.mf6.ModflowTdis(
@@ -506,26 +509,29 @@ def build_model(ws, exe, timeseries=False):
     return sim
 
 
-def test_mf6model(function_tmpdir, targets):
-    mf6 = targets.mf6
+def check_output(idx, test):
+    print("Running surfdep check")
+    with open(test.workspace / "mfsim.lst", "r") as f:
+        lines = f.readlines()
+        error_count = 0
+        for line in lines:
+            if "cprior" and "divflow not within" in line:
+                error_count += 1
 
-    # build and run the test model
-    sim = build_model(str(function_tmpdir), mf6)
-    sim.write_simulation()
-    sim.run_simulation()
+        # ensure that error msg is in mfsim.lst file
+        assert error_count == 1, (
+            "error count = " + str(error_count) + "but should equal 1"
+        )
 
-    # ensure that the error msg is contained in the mfsim.lst file
-    f = open(str(function_tmpdir / "mfsim.lst"), "r")
-    lines = f.readlines()
-    error_count = 0
-    expected_msg = False
-    for line in lines:
-        if "cprior" and "divflow not within" in line:
-            expected_msg = True
-            error_count += 1
 
-    assert error_count == 1, (
-        "error count = " + str(error_count) + "but should equal 1"
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        xfail=True,
     )
-
-    print("Finished running surfdep check")
+    test.run()
diff --git a/autotest/test_gwf_sfr_diversion.py b/autotest/test_gwf_sfr_diversion.py
new file mode 100644
index 00000000000..4ca34d74bd0
--- /dev/null
+++ b/autotest/test_gwf_sfr_diversion.py
@@ -0,0 +1,179 @@
+import os
+
+import flopy
+import numpy as np
+import pytest
+
+from framework import TestFramework
+
+cases = ["sfr_div"]
+inflows = np.array([10, 0, 10, 0, 10])
+diversion = np.array([0.5, 0.5, 0.5, 0.5, 0.0])
+
+
+def build_models(idx, test):
+    # static model data
+    # temporal discretization
+    nper = len(inflows)
+    tdis_rc = [
+        (1.0, 1, 1.0),
+    ] * nper
+
+    # spatial discretization data
+    nlay, nrow, ncol = 1, 1, 1
+    delr, delc = 100.0, 100.0
+    top = 0.0
+    botm = -10.0
+    strt = 0.0
+
+    # build MODFLOW 6 files
+    name = cases[idx]
+    sim = flopy.mf6.MFSimulation(
+        sim_name=name,
+        version="mf6",
+        exe_name="mf6",
+        sim_ws=test.workspace,
+    )
+    sim.simulation_data.verify_data = False
+
+    # create tdis package
+    tdis = flopy.mf6.ModflowTdis(
+        sim,
+        time_units="days",
+        nper=nper,
+        perioddata=tdis_rc,
+    )
+
+    # create iterative model solution and register the gwf model with it
+    ims = flopy.mf6.ModflowIms(
+        sim,
+        print_option="ALL",
+    )
+
+    # create gwf model
+    gwf = flopy.mf6.ModflowGwf(
+        sim,
+        modelname=name,
+    )
+
+    dis = flopy.mf6.ModflowGwfdis(
+        gwf,
+        nlay=nlay,
+        nrow=nrow,
+        ncol=ncol,
+        delr=delr,
+        delc=delc,
+        top=top,
+        botm=botm,
+    )
+
+    # initial conditions
+    ic = flopy.mf6.ModflowGwfic(gwf, strt=strt)
+
+    # node property flow
+    npf = flopy.mf6.ModflowGwfnpf(
+        gwf,
+        icelltype=0,
+    )
+
+    # output control
+    oc = flopy.mf6.ModflowGwfoc(
+        gwf, budget_filerecord=name + ".cbb", saverecord=[["BUDGET", "ALL"]]
+    )
+
+    # sfr file
+    cellid = (0, 0, 0)
+    nreaches = 3
+    rlen = 10.0
+    rwid = 10.0
+    roughness = 0.001
+    rbth = 1.0
+    rhk = 0.0
+    slope = 0.001
+
+    sfrrch_prop = [cellid, rlen, rwid, slope, top, rbth, rhk, roughness]
+    packagedata = [
+        [
+            0,
+        ]
+        + sfrrch_prop
+        + [2, 1.0, 1],
+        [
+            1,
+        ]
+        + sfrrch_prop
+        + [1, 0.0, 0],
+        [
+            2,
+        ]
+        + sfrrch_prop
+        + [1, 1.0, 0],
+    ]
+    connectiondata = [
+        [0, -1, -2],
+        [1, 0],
+        [2, 0],
+    ]
+    diversiondata = [
+        [0, 0, 1, "FRACTION"],
+    ]
+    perioddata = {
+        i: [[0, "inflow", qin], [0, "diversion", 0, qdiv]]
+        for i, (qin, qdiv) in enumerate(zip(inflows, diversion))
+    }
+
+    sfr = flopy.mf6.ModflowGwfsfr(
+        gwf,
+        print_stage=True,
+        print_flows=True,
+        print_input=True,
+        budgetcsv_filerecord=name + ".sfr.csv",
+        budget_filerecord=name + ".sfr.cbb",
+        nreaches=nreaches,
+        packagedata=packagedata,
+        connectiondata=connectiondata,
+        diversions=diversiondata,
+        perioddata=perioddata,
+        pname="sfr-1",
+    )
+
+    return sim, None
+
+
+def check_output(idx, test):
+    # check flow for indivdual reach
+    fname = os.path.join(test.workspace, f"{test.name}.sfr.cbb")
+    with flopy.utils.CellBudgetFile(fname) as cbb:
+        outflows = cbb.get_data(text="EXT-OUTFLOW")
+
+    # check outflow for reach 2 and 3
+    assert np.allclose(
+        [r.q[1] for r in outflows], -inflows * diversion
+    ), "Incorrect outflow for diversion reach"
+    assert np.allclose(
+        [r.q[2] for r in outflows], -inflows * (1 - diversion)
+    ), "Incorrect outflow for outlet reach"
+
+    # load SFR budget CSV and check overall budget
+    with open(fname.replace(".cbb", ".csv")) as f:
+        header = f.readline().strip().split(",")
+        flux = np.loadtxt(f, delimiter=",")
+
+    assert np.allclose(
+        flux[:, header.index("EXT-OUTFLOW_IN")], 0
+    ), "External flow IN larger than zero"
+    assert np.allclose(
+        flux[:, header.index("PERCENT_DIFFERENCE")], 0
+    ), "Large mass balance error in SFR"
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+    )
+    test.run()
diff --git a/autotest/test_gwf_sfr_evap.py b/autotest/test_gwf_sfr_evap.py
index 2e9646680bc..3b820d6b101 100644
--- a/autotest/test_gwf_sfr_evap.py
+++ b/autotest/test_gwf_sfr_evap.py
@@ -1,14 +1,16 @@
-# Test evap in SFR reaches (no interaction with gwf)
+"""
+Test evap in SFR reaches (no interaction with gwf)
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["sfr-evap"]
+cases = ["sfr-evap"]
 
 
 # Model units
@@ -65,15 +67,11 @@
 nouter, ninner = 1000, 300
 hclose, rclose, relax = 1e-3, 1e-4, 0.97
 
-#
-# MODFLOW 6 flopy GWF object
-#
-
 
-def build_model(idx, dir):
+def build_models(idx, test):
     # Base simulation and model name and workspace
-    ws = dir
-    name = ex[idx]
+    ws = test.workspace
+    name = cases[idx]
 
     print("Building model...{}".format(name))
 
@@ -265,7 +263,8 @@ def build_model(idx, dir):
         print_stage=True,
         print_flows=True,
         print_input=True,
-        unit_conversion=1.0 * 86400,
+        length_conversion=1.0,
+        time_conversion=86400.0,
         budget_filerecord=budpth,
         mover=False,
         nreaches=nreaches,
@@ -362,7 +361,8 @@ def build_model(idx, dir):
         print_stage=True,
         print_flows=True,
         print_input=True,
-        unit_conversion=1.0 * 86400,
+        length_conversion=1.0,
+        time_conversion=86400.0,
         budget_filerecord=budpth,
         mover=False,
         nreaches=nreaches,
@@ -376,16 +376,14 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # read flow results from model
-    name = ex[sim.idxsim]
+    name = cases[idx]
     gwfname_t = "gwf-" + name + "-t"
     gwfname_r = "gwf-" + name + "-r"
 
     fname = gwfname_t + ".sfr.cbc"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
 
     sfrobj = flopy.utils.binaryfile.CellBudgetFile(fname, precision="double")
@@ -414,7 +412,7 @@ def eval_results(sim):
 
     # Now check results from standard rectangular x-section setup (not an n-point channel)
     fname2 = gwfname_r + ".sfr.cbc"
-    fname2 = os.path.join(sim.simpath, fname2)
+    fname2 = os.path.join(test.workspace, fname2)
     assert os.path.isfile(fname2)
 
     sfrobj = flopy.utils.binaryfile.CellBudgetFile(fname2, precision="double")
@@ -434,17 +432,13 @@ def eval_results(sim):
     assert np.allclose(stored_strm_evap_r, sim_evap_r, atol=1e-4), msg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_sfr_gwf_conn.py b/autotest/test_gwf_sfr_gwf_conn.py
new file mode 100644
index 00000000000..332eb29a59a
--- /dev/null
+++ b/autotest/test_gwf_sfr_gwf_conn.py
@@ -0,0 +1,283 @@
+import os
+
+import flopy
+import numpy as np
+import pytest
+
+from framework import TestFramework
+
+paktest = "sfr"
+cases = [
+    "sfr_dis",
+    "sfr_dis_fail",
+    "sfr_dis_none",
+    "sfr_disv",
+    "sfr_disv_fail",
+    "sfr_disv_none",
+    "sfr_disu",
+    "sfr_disu_fail",
+    "sfr_disu_none",
+]
+dis_types = [
+    "dis",
+    "dis",
+    "dis",
+    "disv",
+    "disv",
+    "disv",
+    "disu",
+    "disu",
+    "disu",
+]
+
+# spatial discretization data
+nlay, nrow, ncol = 1, 1, 1
+delr, delc = 100.0, 100.0
+top = 0.0
+botm = -10.0
+strt = 0.0
+
+# spatial discretization data for disv and disu
+vertices = [(0, 0.0, 0.0), (1, 0.0, delc), (2, delr, delc), (3, delr, 0.0)]
+cell2d = [(0, delr / 2.0, delc / 2.0, 4, 0, 1, 2, 3)]
+
+# sfr data
+nreaches = 10
+rlen = 10.0
+rwid = 10.0
+roughness = 0.001
+rbth = 1.0
+rhk = 0.0
+slope = 0.001
+ustrf = 1.0
+ndv = 0
+
+
+def build_model(idx, ws):
+    # static model data
+    # temporal discretization
+    nper = 1
+    tdis_rc = [(11.0, 11, 1.0)]
+    ts_times = np.arange(0.0, 12.0, 1.0, dtype=float)
+    ts_flows = np.array([1000.0] + [float(q) for q in range(1000, -100, -100)])
+
+    # build MODFLOW 6 files
+    name = cases[idx]
+    dis_type = dis_types[idx]
+    sim = flopy.mf6.MFSimulation(
+        sim_name=name,
+        version="mf6",
+        exe_name="mf6",
+        sim_ws=ws,
+    )
+    sim.simulation_data.verify_data = False
+
+    # create tdis package
+    tdis = flopy.mf6.ModflowTdis(
+        sim,
+        time_units="seconds",
+        nper=nper,
+        perioddata=tdis_rc,
+    )
+
+    # create iterative model solution and register the gwf model with it
+    ims = flopy.mf6.ModflowIms(
+        sim,
+        print_option="ALL",
+    )
+
+    # create gwf model
+    gwf = flopy.mf6.ModflowGwf(
+        sim,
+        modelname=name,
+    )
+
+    if dis_type == "dis":
+        dis = flopy.mf6.ModflowGwfdis(
+            gwf,
+            length_units="meters",
+            nlay=nlay,
+            nrow=nrow,
+            ncol=ncol,
+            delr=delr,
+            delc=delc,
+            top=top,
+            botm=botm,
+            idomain=1,
+        )
+    elif dis_type == "disv":
+        dis = flopy.mf6.ModflowGwfdisv(
+            gwf,
+            length_units="meters",
+            nlay=nlay,
+            ncpl=1,
+            nvert=4,
+            vertices=vertices,
+            cell2d=cell2d,
+            top=top,
+            botm=botm,
+            idomain=1,
+        )
+    else:
+        disukwargs = flopy.utils.gridutil.get_disu_kwargs(
+            nlay,
+            nrow,
+            ncol,
+            [delr],
+            [delc],
+            top,
+            [botm],
+        )
+        dis = flopy.mf6.ModflowGwfdisu(
+            gwf,
+            vertices=vertices,
+            cell2d=cell2d,
+            **disukwargs,
+        )
+
+    # initial conditions
+    ic = flopy.mf6.ModflowGwfic(gwf, strt=strt)
+
+    # node property flow
+    npf = flopy.mf6.ModflowGwfnpf(gwf)
+
+    # chd files
+    # chd data
+    if dis_type == "dis":
+        spd = [
+            [(0, 0, 0), 0.0],
+        ]
+    elif dis_type == "disv":
+        spd = [
+            [(0, 0), 0.0],
+        ]
+    else:
+        spd = [
+            [(0,), 0.0],
+        ]
+
+    chd = flopy.mf6.modflow.ModflowGwfchd(
+        gwf, maxbound=1, stress_period_data=spd, pname="chd-1"
+    )
+
+    # sfr file
+    if dis_type == "dis":
+        if "fail" in name:
+            cellid = (2, 2, 2)
+        elif "none" in name:
+            cellid = "none"
+        else:
+            cellid = (-1, -1, -1)
+    elif dis_type == "disv":
+        if "fail" in name:
+            cellid = (2, 2)
+        elif "none" in name:
+            cellid = "none"
+        else:
+            cellid = (-1, -1)
+    else:
+        if "fail" in name:
+            cellid = (2,)
+        elif "none" in name:
+            cellid = "none"
+        else:
+            cellid = (-1,)
+    packagedata = []
+    for irch in range(nreaches):
+        nconn = 1
+        if 0 < irch < nreaches - 1:
+            nconn += 1
+        rp = [
+            irch,
+            cellid,
+            rlen,
+            rwid,
+            slope,
+            top,
+            rbth,
+            rhk,
+            roughness,
+            nconn,
+            ustrf,
+            ndv,
+        ]
+        packagedata.append(rp)
+
+    if not str(ws).endswith("mf6"):
+        packagedata = packagedata[::-1]
+
+    connectiondata = []
+    inflow_loc = 0
+    ioutflow_loc = nreaches - 1
+    for irch in range(nreaches):
+        rc = [irch]
+        if irch > 0:
+            rc.append(irch - 1)
+        if irch < nreaches - 1:
+            rc.append(-(irch + 1))
+        connectiondata.append(rc)
+
+    ts_names = ["inflow"]
+    perioddata = [
+        [inflow_loc, "inflow", "inflow"],
+    ]
+    ts_methods = ["linearend"] * len(ts_names)
+    ts_data = []
+    for t, q in zip(ts_times, ts_flows):
+        ts_data.append((t, q))
+
+    sfr = flopy.mf6.ModflowGwfsfr(
+        gwf,
+        print_stage=True,
+        print_flows=True,
+        print_input=True,
+        mover=True,
+        nreaches=nreaches,
+        packagedata=packagedata,
+        connectiondata=connectiondata,
+        perioddata=perioddata,
+        pname="sfr-1",
+    )
+    fname = f"{name}.sfr.ts"
+    sfr.ts.initialize(
+        filename=fname,
+        timeseries=ts_data,
+        time_series_namerecord=ts_names,
+        interpolation_methodrecord=ts_methods,
+    )
+    fname = f"{name}.sfr.obs"
+    sfr_obs = {
+        f"{fname}.csv": [
+            ("inflow", "ext-inflow", (inflow_loc,)),
+            ("outflow", "ext-outflow", (ioutflow_loc,)),
+        ]
+    }
+    sfr.obs.initialize(filename=fname, print_input=True, continuous=sfr_obs)
+
+    # output control
+    oc = flopy.mf6.ModflowGwfoc(
+        gwf,
+        printrecord=[
+            ("BUDGET", "ALL"),
+        ],
+    )
+
+    return sim
+
+
+def build_models(idx, test):
+    sim = build_model(idx, test.workspace)
+    return sim, None
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        compare=None,
+        xfail="fail" in name,
+    )
+    test.run()
diff --git a/autotest/test_gwf_sfr_npoint01.py b/autotest/test_gwf_sfr_npoint01.py
index 7579e1b2025..7d654809633 100644
--- a/autotest/test_gwf_sfr_npoint01.py
+++ b/autotest/test_gwf_sfr_npoint01.py
@@ -3,12 +3,12 @@
 import flopy
 import numpy as np
 import pytest
+
 from cross_section_functions import get_depths
 from framework import TestFramework
-from simulation import TestSimulation
 
 paktest = "sfr"
-ex = [
+cases = [
     "sfr_npt01a",
     "sfr_npt01b",
     "sfr_npt01c",
@@ -117,9 +117,7 @@
 }
 
 
-#
-def build_model(idx, ws):
-
+def build_models(idx, test):
     xsect_type = xsect_types[idx]
 
     # static model data
@@ -130,12 +128,12 @@ def build_model(idx, ws):
     ts_flows = np.array([1000.0] + [float(q) for q in range(1000, -100, -100)])
 
     # build MODFLOW 6 files
-    name = ex[idx]
+    name = cases[idx]
     sim = flopy.mf6.MFSimulation(
         sim_name=name,
         version="mf6",
         exe_name="mf6",
-        sim_ws=ws,
+        sim_ws=test.workspace,
     )
     # create tdis package
     tdis = flopy.mf6.ModflowTdis(
@@ -299,10 +297,8 @@ def build_model(idx, ws):
     return sim, None
 
 
-def eval_npointq(sim, idx):
-    print("evaluating n-point cross-section results..." f"({sim.name})")
-
-    obs_pth = os.path.join(sim.simpath, f"{sim.name}.sfr.obs.csv")
+def check_output(idx, test):
+    obs_pth = os.path.join(test.workspace, f"{test.name}.sfr.obs.csv")
     obs = flopy.utils.Mf6Obs(obs_pth).get_data()
 
     assert np.allclose(
@@ -327,20 +323,13 @@ def eval_npointq(sim, idx):
     )
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=lambda s: eval_npointq(s, idx),
-            idxsim=idx,
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_sfr_npoint02.py b/autotest/test_gwf_sfr_npoint02.py
index db51e9238da..ee987d1ae5d 100644
--- a/autotest/test_gwf_sfr_npoint02.py
+++ b/autotest/test_gwf_sfr_npoint02.py
@@ -3,13 +3,13 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
+
 from cross_section_functions import get_depths
+from framework import TestFramework
 
 paktest = "sfr"
 
-ex = [
+cases = [
     "sfr_npt02a",
 ]
 
@@ -53,15 +53,14 @@ def flow_to_depth_wide(rwid, q):
     return ((q * roughness) / (conversion_fact * rwid * np.sqrt(slope))) ** 0.6
 
 
-#
-def build_model(idx, ws):
+def build_models(idx, test):
     # build MODFLOW 6 files
-    name = ex[idx]
+    name = cases[idx]
     sim = flopy.mf6.MFSimulation(
         sim_name=name,
         version="mf6",
         exe_name="mf6",
-        sim_ws=ws,
+        sim_ws=test.workspace,
     )
     # create tdis package
     tdis = flopy.mf6.ModflowTdis(
@@ -209,11 +208,9 @@ def build_model(idx, ws):
     return sim, None
 
 
-def eval_npointdepth(sim):
-    name = sim.name
-    print("evaluating n-point cross-section results..." f"({name})")
-
-    obs_pth = os.path.join(sim.simpath, f"{name}.sfr.obs.csv")
+def check_output(idx, test):
+    name = test.name
+    obs_pth = os.path.join(test.workspace, f"{name}.sfr.obs.csv")
     obs = flopy.utils.Mf6Obs(obs_pth).get_data()
 
     assert np.allclose(
@@ -242,20 +239,13 @@ def eval_npointdepth(sim):
     ), "sfr depth not equal to calculated depth"
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_npointdepth,
-            idxsim=0,
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_sfr_npoint03.py b/autotest/test_gwf_sfr_npoint03.py
index d7ae482e611..00eaecdec3d 100644
--- a/autotest/test_gwf_sfr_npoint03.py
+++ b/autotest/test_gwf_sfr_npoint03.py
@@ -3,12 +3,12 @@
 import flopy
 import numpy as np
 import pytest
+
 from cross_section_functions import calculate_rectchan_mannings_discharge
 from framework import TestFramework
-from simulation import TestSimulation
 
 paktest = "sfr"
-ex = [
+cases = [
     "sfr_npt03a",
     "sfr_npt03b",
     "sfr_npt03c",
@@ -69,13 +69,13 @@
 # x: 0          1/3         2/3          1
 #
 
-def build_model(idx, ws, base=False):
 
+def build_model(idx, ws, base=False):
     if base:
         ws = os.path.join(ws, "mf6")
 
     # build MODFLOW 6 files
-    name = ex[idx]
+    name = cases[idx]
     sim = flopy.mf6.MFSimulation(
         sim_name=name,
         version="mf6",
@@ -269,44 +269,39 @@ def build_model(idx, ws, base=False):
     return sim
 
 
-def build_models(idx, ws):
-    sim = build_model(idx, ws)
-    mc = build_model(idx, ws, base=True)
+def build_models(idx, test):
+    sim = build_model(idx, test.workspace)
+    mc = build_model(idx, test.workspace, base=True)
     return sim, mc
 
 
-def eval_npointdepth(sim):
-    print("evaluating n-point cross-section results..." f"({sim.name})")
-
-    obs_pth0 = os.path.join(sim.simpath, f"{sim.name}.sfr.obs.csv")
+def check_output(idx, test):
+    obs_pth0 = os.path.join(test.workspace, f"{test.name}.sfr.obs.csv")
     obs0 = np.genfromtxt(obs_pth0, names=True, delimiter=",")
 
-    obs_pth1 = os.path.join(sim.simpath, "mf6", f"{sim.name}.sfr.obs.csv")
+    obs_pth1 = os.path.join(test.workspace, "mf6", f"{test.name}.sfr.obs.csv")
     obs1 = np.genfromtxt(obs_pth1, names=True, delimiter=",")
 
     q0 = obs0["OUTFLOW_DOWNSTREAM"]
     q1 = obs1["OUTFLOW_DOWNSTREAM"]
-    assert np.allclose(q0, q1), f"downstream outflows not equal ('{sim.name}')"
+    assert np.allclose(
+        q0, q1
+    ), f"downstream outflows not equal ('{test.name}')"
 
     d0 = obs0["DEPTH_UPSTREAM"]
     d1 = obs1["DEPTH_UPSTREAM"]
-    assert np.allclose(d0, d1), f"upstream depths are not equal ('{sim.name}')"
+    assert np.allclose(
+        d0, d1
+    ), f"upstream depths are not equal ('{test.name}')"
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_models, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_npointdepth,
-            idxsim=idx,
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_sfr_reorder.py b/autotest/test_gwf_sfr_reorder.py
index 2010b7a24cd..5aafcf3b7a4 100644
--- a/autotest/test_gwf_sfr_reorder.py
+++ b/autotest/test_gwf_sfr_reorder.py
@@ -3,11 +3,11 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
 paktest = "sfr"
-ex = ["sfr_reorder"]
+cases = ["sfr_reorder"]
 
 # spatial discretization data
 nlay, nrow, ncol = 1, 1, 1
@@ -29,7 +29,6 @@
 
 
 def build_model(idx, ws):
-
     # static model data
     # temporal discretization
     nper = 1
@@ -38,7 +37,7 @@ def build_model(idx, ws):
     ts_flows = np.array([1000.0] + [float(q) for q in range(1000, -100, -100)])
 
     # build MODFLOW 6 files
-    name = ex[idx]
+    name = cases[idx]
     sim = flopy.mf6.MFSimulation(
         sim_name=name,
         version="mf6",
@@ -115,11 +114,11 @@ def build_model(idx, ws):
         ]
         packagedata.append(rp)
 
-    if not ws.endswith("mf6"):
+    if not str(ws).endswith("mf6"):
         packagedata = packagedata[::-1]
 
     connectiondata = []
-    if not ws.endswith("mf6"):
+    if not str(ws).endswith("mf6"):
         inflow_loc = nreaches - 1
         ioutflow_loc = 0
         for irch in range(inflow_loc, -1, -1):
@@ -195,23 +194,18 @@ def build_model(idx, ws):
     return sim
 
 
-def build_models(idx, base_ws):
-    sim = build_model(idx, base_ws)
-
-    ws = os.path.join(base_ws, "mf6")
-    mc = build_model(idx, ws)
-
+def build_models(idx, test):
+    sim = build_model(idx, test.workspace)
+    mc = build_model(idx, os.path.join(test.workspace, "mf6"))
     return sim, mc
 
 
-def eval_flows(sim):
-    name = sim.name
-    print("evaluating flow results..." f"({name})")
-
-    obs_pth = os.path.join(sim.simpath, f"{name}.sfr.obs.csv")
+def check_output(idx, test):
+    name = test.name
+    obs_pth = os.path.join(test.workspace, f"{name}.sfr.obs.csv")
     obs0 = flopy.utils.Mf6Obs(obs_pth).get_data()
 
-    obs_pth = os.path.join(sim.simpath, "mf6", f"{name}.sfr.obs.csv")
+    obs_pth = os.path.join(test.workspace, "mf6", f"{name}.sfr.obs.csv")
     obs1 = flopy.utils.Mf6Obs(obs_pth).get_data()
 
     assert np.allclose(obs0["INFLOW"], obs1["INFLOW"]), "inflows are not equal"
@@ -220,16 +214,16 @@ def eval_flows(sim):
         obs0["OUTFLOW"], obs1["OUTFLOW"]
     ), "outflows are not equal"
 
-    fpth = os.path.join(sim.simpath, f"{name}.lst")
+    fpth = os.path.join(test.workspace, f"{name}.lst")
     with open(fpth, "r") as f:
         lines = f.read().splitlines()
 
     # check order in listing file
     order = np.zeros(nreaches, dtype=int)
-    for idx, line in enumerate(lines):
+    for i, line in enumerate(lines):
         if "SFR PACKAGE (SFR-1) REACH SOLUTION ORDER" in line:
             for jdx in range(nreaches):
-                ipos = idx + 4 + jdx
+                ipos = i + 4 + jdx
                 t = lines[ipos].split()
                 order[int(t[0]) - 1] = int(t[1])
             order -= 1
@@ -241,20 +235,13 @@ def eval_flows(sim):
     ), "DAG did not correctly reorder reaches."
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_models, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_flows,
-            idxsim=idx,
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_sfr_wetstrmbedarea.py b/autotest/test_gwf_sfr_wetstrmbedarea.py
index 6b46250e5ca..d3143f29bbe 100644
--- a/autotest/test_gwf_sfr_wetstrmbedarea.py
+++ b/autotest/test_gwf_sfr_wetstrmbedarea.py
@@ -1,15 +1,15 @@
 # Test evap in SFR reaches (no interaction with gwf)
 
+import math
 import os
 
 import flopy
 import numpy as np
 import pytest
-import math
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["sfr-wetperim"]
+cases = ["sfr-wetperim"]
 
 
 def get_x_frac(x_coord1, rwid):
@@ -87,19 +87,20 @@ def get_xy_pts(x, y, rwid):
 )
 x_sec_tab = [x_sec_tab1, x_sec_tab2, x_sec_tab3]
 
+
 def calc_wp(j, stg):
     if j < 2:
         rise = 1 / 3
         run = 2
-        bot_wid = 1.
+        bot_wid = 1.0
     elif j < 4:
         rise = 1 / 4
         run = 2
-        bot_wid = 2.
+        bot_wid = 2.0
     else:
         rise = 1 / 6
         run = 4
-        bot_wid = 4.
+        bot_wid = 4.0
 
     ang = math.atan2(rise, run)
     hyp_len = stg / math.sin(ang)
@@ -107,6 +108,7 @@ def calc_wp(j, stg):
 
     return wp
 
+
 # time params
 steady = {0: True, 1: False}
 transient = {0: False, 1: True}
@@ -117,15 +119,11 @@ def calc_wp(j, stg):
 nouter, ninner = 1000, 300
 hclose, rclose, relax = 1e-3, 1e-4, 0.97
 
-#
-# MODFLOW 6 flopy GWF object
-#
-
 
-def build_model(idx, dir):
+def build_models(idx, test):
     # Base simulation and model name and workspace
-    ws = dir
-    name = ex[idx]
+    ws = test.workspace
+    name = cases[idx]
 
     print("Building model...{}".format(name))
 
@@ -331,22 +329,20 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # read flow results from model
-    name = ex[sim.idxsim]
+    name = cases[idx]
     gwfname = "gwf-" + name
 
     fname = gwfname + ".sfr.cbc"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
 
     sfrobj = flopy.utils.binaryfile.CellBudgetFile(fname, precision="double")
     sfr_wetted_interface_area = sfrobj.get_data(text="gwf")
 
     # Retrieve simulated stage of each reach
-    sfr_pth0 = os.path.join(sim.simpath, f"{gwfname}.sfr.obs.csv")
+    sfr_pth0 = os.path.join(test.workspace, f"{gwfname}.sfr.obs.csv")
     sfrstg = np.genfromtxt(sfr_pth0, names=True, delimiter=",")
 
     # Extract shared wetted interfacial areas
@@ -365,8 +361,9 @@ def eval_results(sim):
         wp = calc_wp(j, stg)
         wa = wp * delr
         msg = (
-            "Wetted streambed area for reach " + str(j) +
-            "in stress period 1 does not match explicitly-calculated answer"
+            "Wetted streambed area for reach "
+            + str(j)
+            + "in stress period 1 does not match explicitly-calculated answer"
         )
         assert np.isclose(wa, shared_area[0, j], atol=1e-4), msg
 
@@ -378,17 +375,13 @@ def eval_results(sim):
         assert val == 0.0, msg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_sto01.py b/autotest/test_gwf_sto01.py
index c5328e0b3f5..b52f551aced 100644
--- a/autotest/test_gwf_sto01.py
+++ b/autotest/test_gwf_sto01.py
@@ -3,13 +3,13 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["gwf_sto01"]
+cases = ["gwf_sto01"]
 cmppth = "mfnwt"
 tops = [0.0]
-htol = [None for idx in range(len(ex))]
+htol = [None for _ in range(len(cases))]
 dtol = 1e-3
 budtol = 1e-2
 bud_lst = ["STO-SS_IN", "STO-SS_OUT", "STO-SY_IN", "STO-SY_OUT"]
@@ -17,14 +17,14 @@
 # static model data
 # temporal discretization
 nper = 31
-perlen = [1.0] + [365.2500000 for i in range(nper - 1)]
-nstp = [1] + [6 for i in range(nper - 1)]
-tsmult = [1.0] + [1.3 for i in range(nper - 1)]
+perlen = [1.0] + [365.2500000 for _ in range(nper - 1)]
+nstp = [1] + [6 for _ in range(nper - 1)]
+tsmult = [1.0] + [1.3 for _ in range(nper - 1)]
 # tsmult = [1.0] + [1.0 for i in range(nper - 1)]
-steady = [True] + [False for i in range(nper - 1)]
+steady = [True] + [False for _ in range(nper - 1)]
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 # spatial discretization data
 nlay, nrow, ncol = 3, 10, 10
@@ -94,12 +94,13 @@
 # storage and compaction data
 ske = [6e-4, 3e-4, 6e-4]
 
+
 # variant SUB package problem 3
-def build_model(idx, dir):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -200,8 +201,10 @@ def build_model(idx, dir):
 
     # build MODFLOW-NWT files
     cpth = cmppth
-    ws = os.path.join(dir, cpth)
-    mc = flopy.modflow.Modflow(name, model_ws=ws, version=cpth)
+    ws = os.path.join(test.workspace, cpth)
+    mc = flopy.modflow.Modflow(
+        name, model_ws=ws, version=cpth, exe_name=test.targets["mfnwt"]
+    )
     dis = flopy.modflow.ModflowDis(
         mc,
         nlay=nlay,
@@ -255,12 +258,9 @@ def build_model(idx, dir):
     return sim, mc
 
 
-def eval_sto(sim):
-
-    print("evaluating storage...")
-
+def check_output(idx, test):
     # get results from listing file
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.lst")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.lst")
     budl = flopy.utils.Mf6ListBudget(fpth)
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
@@ -272,11 +272,11 @@ def eval_sto(sim):
     d = np.recarray(nbud, dtype=dtype)
     for key in bud_lst:
         d[key] = 0.0
-    fpth = os.path.join(sim.simpath, f"{os.path.basename(sim.name)}.cbc")
+    fpth = os.path.join(test.workspace, f"{os.path.basename(test.name)}.cbc")
     cobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -294,65 +294,57 @@ def eval_sto(sim):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, key in enumerate(bud_lst):
-        diff[:, idx] = d0[key] - d[key]
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
     diffmax = np.abs(diff).max()
     msg = f"maximum absolute total-budget difference ({diffmax}) "
 
     # write summary
     fpth = os.path.join(
-        sim.simpath, f"{os.path.basename(sim.name)}.bud.cmp.out"
+        test.workspace, f"{os.path.basename(test.name)}.bud.cmp.out"
     )
-    f = open(fpth, "w")
-    for i in range(diff.shape[0]):
-        if i == 0:
-            line = f"{'TIME':>10s}"
-            for idx, key in enumerate(bud_lst):
-                line += f"{key + '_LST':>25s}"
-                line += f"{key + '_CBC':>25s}"
-                line += f"{key + '_DIF':>25s}"
+    with open(fpth, "w") as f:
+        for i in range(diff.shape[0]):
+            if i == 0:
+                line = f"{'TIME':>10s}"
+                for key in bud_lst:
+                    line += f"{key + '_LST':>25s}"
+                    line += f"{key + '_CBC':>25s}"
+                    line += f"{key + '_DIF':>25s}"
+                f.write(line + "\n")
+            line = f"{d['totim'][i]:10g}"
+            for ii, key in enumerate(bud_lst):
+                line += f"{d0[key][i]:25g}"
+                line += f"{d[key][i]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
-        line = f"{d['totim'][i]:10g}"
-        for idx, key in enumerate(bud_lst):
-            line += f"{d0[key][i]:25g}"
-            line += f"{d[key][i]:25g}"
-            line += f"{diff[i, idx]:25g}"
-        f.write(line + "\n")
-    f.close()
 
     if diffmax > budtol:
-        sim.success = False
+        test.success = False
         msg += f"exceeds {dtol}"
         assert diffmax < dtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_sto,
-            htol=htol[idx],
-            idxsim=idx,
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
+        htol=htol[idx],
     )
+    test.run()
diff --git a/autotest/test_gwf_sto02.py b/autotest/test_gwf_sto02.py
index b2dd7ea9871..da1d9f355ad 100644
--- a/autotest/test_gwf_sto02.py
+++ b/autotest/test_gwf_sto02.py
@@ -1,6 +1,5 @@
 """
 Test adaptive time step module
-
 """
 
 import os
@@ -8,19 +7,21 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["gwf_sto02a", "gwf_sto02b"]
+cases = ["gwf_sto02a", "gwf_sto02b"]
 ncols = [1, 2]
-nlay, nrow, = (
+(
+    nlay,
+    nrow,
+) = (
     1,
     1,
 )
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     perlen = [10]
     nper = len(perlen)
     nstp = [1]
@@ -39,11 +40,11 @@ def build_model(idx, dir):
     for id in range(nper):
         tdis_rc.append((perlen[id], nstp[id], tsmult[id]))
 
-    name = ex[idx]
+    name = cases[idx]
     ncol = ncols[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -140,14 +141,12 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_flow(sim):
-    print("evaluating flow...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwfname = "gwf_" + name
 
     # This will fail if budget numbers cannot be read
-    fpth = os.path.join(sim.simpath, f"{gwfname}.lst")
+    fpth = os.path.join(test.workspace, f"{gwfname}.lst")
     mflist = flopy.utils.Mf6ListBudget(fpth)
     names = mflist.get_record_names()
     print(names)
@@ -156,20 +155,13 @@ def eval_flow(sim):
     print(inc)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_flow,
-            idxsim=idx,
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_sto03.py b/autotest/test_gwf_sto03.py
index b626b632d5a..4e0c078ed84 100644
--- a/autotest/test_gwf_sto03.py
+++ b/autotest/test_gwf_sto03.py
@@ -3,10 +3,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = [
+cases = [
     "gwf_sto03a",
     "gwf_sto03b",
 ]
@@ -15,7 +15,7 @@
     True,
 )
 cmppth = "mf6"
-htol = [None for idx in range(len(ex))]
+htol = [None for _ in range(len(cases))]
 dtol = 1e-3
 budtol = 1e-2
 
@@ -31,8 +31,8 @@
 nstp = [50 for i in range(nper)]
 tsmult = [1.1 for i in range(nper)]
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 # spatial discretization data
 nlay, nrow, ncol = 1, 1, 1
@@ -62,12 +62,12 @@
 # pumping well data
 absrate = 1.1 * ss * (zelev[-2] - zelev[-1]) * 90.0
 well_spd = {}
-for idx in range(nper):
-    if idx % 2 == 0:
+for i in range(nper):
+    if i % 2 == 0:
         mult = 1.0
     else:
         mult = -1.0
-    well_spd[idx] = [[0, 0, 0, mult * absrate]]
+    well_spd[i] = [[0, 0, 0, mult * absrate]]
 
 
 def get_model(name, ws, newton_bool, offset=0.0):
@@ -172,16 +172,17 @@ def get_model(name, ws, newton_bool, offset=0.0):
 
 
 # variant SUB package problem 3
-def build_model(idx, dir):
-    name = ex[idx]
-    ws = dir
-
-    # build model with no offset
-    sim = get_model(name, ws, newton_bool=newton[idx])
-
-    # build model with offset
-    ws = os.path.join(dir, cmppth)
-    mc = get_model(name, ws, newton_bool=newton[idx], offset=cmp_offset)
+def build_models(idx, test):
+    name = cases[idx]
+    # model with no offset
+    sim = get_model(name, test.workspace, newton_bool=newton[idx])
+    # model with offset
+    mc = get_model(
+        name,
+        os.path.join(test.workspace, cmppth),
+        newton_bool=newton[idx],
+        offset=cmp_offset,
+    )
     return sim, mc
 
 
@@ -192,23 +193,21 @@ def eval_hmax(fpth):
     bv = np.zeros(ctimes.shape, dtype=float)
     bv[:] = b.get_data(totim=1.0)[obsname]
     sv = np.zeros(ctimes.shape, dtype=float)
-    for idx, t in enumerate(ctimes):
-        sv[idx] = b.get_data(totim=t)[obsname]
+    for i, t in enumerate(ctimes):
+        sv[i] = b.get_data(totim=t)[obsname]
 
     msg = (
         "maximum heads in {} exceed tolerance ".format(fpth)
         + f"- maximum difference {(bv - sv).max()}"
     )
     assert np.allclose(bv, sv), msg
-    return
 
 
-def eval_sto(sim):
-    print("evaluating head differences...")
-    fpth = os.path.join(sim.simpath, "head.obs.csv")
+def check_output(idx, test):
+    fpth = os.path.join(test.workspace, "head.obs.csv")
     base_obs = flopy.utils.Mf6Obs(fpth).get_data()[obsname]
 
-    fpth = os.path.join(sim.simpath, cmppth, "head.obs.csv")
+    fpth = os.path.join(test.workspace, cmppth, "head.obs.csv")
     offset_obs = flopy.utils.Mf6Obs(fpth).get_data()[obsname]
     offset_obs -= cmp_offset
 
@@ -218,10 +217,9 @@ def eval_sto(sim):
     )
     assert np.allclose(base_obs, offset_obs, atol=1e-6), msg
 
-    print("evaluating maximum heads...")
-    fpth = os.path.join(sim.simpath, "head.obs.csv")
+    fpth = os.path.join(test.workspace, "head.obs.csv")
     eval_hmax(fpth)
-    fpth = os.path.join(sim.simpath, cmppth, "head.obs.csv")
+    fpth = os.path.join(test.workspace, cmppth, "head.obs.csv")
     eval_hmax(fpth)
 
     base_obs = flopy.utils.Mf6Obs(fpth)
@@ -230,8 +228,8 @@ def eval_sto(sim):
     base_cmp = np.zeros(cmp_times.shape, dtype=float)
     base_cmp[:] = base_obs.get_data(totim=1.0)[obsname]
     offset_cmp = np.zeros(cmp_times.shape, dtype=float)
-    for idx, t in enumerate(cmp_times):
-        offset_cmp[idx] = base_obs.get_data(totim=t)[obsname]
+    for i, t in enumerate(cmp_times):
+        offset_cmp[i] = base_obs.get_data(totim=t)[obsname]
 
     msg = (
         "maximum heads exceed tolerance when offset removed "
@@ -239,11 +237,10 @@ def eval_sto(sim):
     )
     assert np.allclose(base_cmp, offset_cmp), msg
 
-    print("evaluating storage...")
-    name = ex[sim.idxsim]
-    fpth = os.path.join(sim.simpath, f"{name}.cbc")
+    name = cases[idx]
+    fpth = os.path.join(test.workspace, f"{name}.cbc")
     base_cbc = flopy.utils.CellBudgetFile(fpth, precision="double")
-    fpth = os.path.join(sim.simpath, cmppth, f"{name}.cbc")
+    fpth = os.path.join(test.workspace, cmppth, f"{name}.cbc")
     offset_cbc = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # get results from cbc file
@@ -251,31 +248,24 @@ def eval_sto(sim):
     kk = base_cbc.get_kstpkper()
     times = base_cbc.get_times()
     max_diff = np.zeros(len(times), dtype=float)
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             base_v = base_cbc.get_data(totim=t, text=text)[0]
             offset_v = offset_cbc.get_data(totim=t, text=text)[0]
             if not np.allclose(base_v, offset_v):
-                max_diff[idx] = np.abs(base_v - offset_v).max()
+                max_diff[i] = np.abs(base_v - offset_v).max()
 
     assert max_diff.sum() == 0.0, "simulated storage is not the same"
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_sto,
-            htol=htol[idx],
-            idxsim=idx,
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        htol=htol[idx],
     )
+    test.run()
diff --git a/autotest/test_gwf_sto_tvs01.py b/autotest/test_gwf_sto_tvs01.py
index 1f0f9da6023..7ab1ada5646 100644
--- a/autotest/test_gwf_sto_tvs01.py
+++ b/autotest/test_gwf_sto_tvs01.py
@@ -3,13 +3,13 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["tvs01"]
+cases = ["tvs01"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 1
     perlen = [1.0, 1.0, 1.0, 1.0, 1.0]
     nper = len(perlen)
@@ -37,10 +37,10 @@ def build_model(idx, dir):
     for i in range(nper):
         transient[i] = True
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -162,13 +162,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
-    gwfname = "gwf_" + sim.name
+def check_output(idx, test):
+    gwfname = "gwf_" + test.name
 
     # head
-    fpth = os.path.join(sim.simpath, f"{gwfname}.hds")
+    fpth = os.path.join(test.workspace, f"{gwfname}.hds")
     try:
         hobj = flopy.utils.HeadFile(fpth, precision="double")
         head = hobj.get_alldata()
@@ -193,29 +191,19 @@ def eval_model(sim):
 
     for kper, expected_result in enumerate(expected_results):
         h = head[kper, ex_lay - 1, ex_row - 1, ex_col - 1]
-
         print(kper, h, expected_result)
-
-        errmsg = (
-            f"Expected head {expected_result} in period {kper} but found {h}"
-        )
-        assert np.isclose(h, expected_result)
-
-    # comment when done testing
-    # assert False
-
-
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=0
-        ),
-        ws,
+        assert np.isclose(
+            h, expected_result
+        ), f"Expected head {expected_result} in period {kper} but found {h}"
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_tdis.py b/autotest/test_gwf_tdis.py
index c7f62c7e9f2..ebb188ed0f6 100644
--- a/autotest/test_gwf_tdis.py
+++ b/autotest/test_gwf_tdis.py
@@ -26,7 +26,7 @@ def simple_sim(tmp_path):
 
 
 @pytest.mark.parametrize("tsmult", [1.0, 1.2])
-def test_tdis_tsmult(tsmult, libmf6_path, simple_sim):
+def test_tdis_tsmult(tsmult, simple_sim, targets):
     """Check totim values to ensure they avoid accumulation errors."""
     sim = simple_sim
 
@@ -43,7 +43,7 @@ def test_tdis_tsmult(tsmult, libmf6_path, simple_sim):
     tdis.write()
 
     # Run within libmf6
-    mf6 = XmiWrapper(lib_path=libmf6_path, working_directory=sim.sim_path)
+    mf6 = XmiWrapper(lib_path=targets["libmf6"], working_directory=sim.sim_path)
 
     mf6.initialize()
     dt_list = []
diff --git a/autotest/test_gwf_ts_lak01.py b/autotest/test_gwf_ts_lak01.py
index 4a75c181cff..84b658c65c8 100644
--- a/autotest/test_gwf_ts_lak01.py
+++ b/autotest/test_gwf_ts_lak01.py
@@ -4,12 +4,12 @@
 import numpy as np
 import pytest
 from flopy.utils.compare import eval_bud_diff
+
 from framework import TestFramework
-from simulation import TestSimulation
 
 paktest = "lak"
 budtol = 1e-2
-ex = ["ts_lak01"]
+cases = ["ts_lak01"]
 
 # static model data
 # spatial discretization
@@ -313,57 +313,51 @@ def get_model(ws, name, timeseries=False):
     return sim
 
 
-def build_model(idx, dir):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = get_model(ws, name)
 
     # build MODFLOW 6 files with UZF package
-    ws = os.path.join(dir, "mf6")
+    ws = os.path.join(test.workspace, "mf6")
     mc = get_model(ws, name, timeseries=True)
 
     return sim, mc
 
 
-def eval_budget(sim):
-    print("evaluating budgets...")
-
+def check_output(idx, test):
     # get ia/ja from binary grid file
-    fname = f"{os.path.basename(sim.name)}.dis.grb"
-    fpth = os.path.join(sim.simpath, fname)
+    fname = f"{os.path.basename(test.name)}.dis.grb"
+    fpth = os.path.join(test.workspace, fname)
     grbobj = flopy.mf6.utils.MfGrdFile(fpth)
     ia = grbobj._datadict["IA"] - 1
 
-    fname = f"{os.path.basename(sim.name)}.cbc"
+    fname = f"{os.path.basename(test.name)}.cbc"
 
     # open first cbc file
-    fpth = os.path.join(sim.simpath, fname)
+    fpth = os.path.join(test.workspace, fname)
     cobj0 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # open second cbc file
-    fpth = os.path.join(sim.simpath, "mf6", fname)
+    fpth = os.path.join(test.workspace, "mf6", fname)
     cobj1 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # define file path and evaluate difference
-    fname = f"{os.path.basename(sim.name)}.cbc.cmp.out"
-    fpth = os.path.join(sim.simpath, fname)
+    fname = f"{os.path.basename(test.name)}.cbc.cmp.out"
+    fpth = os.path.join(test.workspace, fname)
     eval_bud_diff(fpth, cobj0, cobj1, ia, dtol=0.1)
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_budget, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_ts_maw01.py b/autotest/test_gwf_ts_maw01.py
index 53a89583870..c752f71ce60 100644
--- a/autotest/test_gwf_ts_maw01.py
+++ b/autotest/test_gwf_ts_maw01.py
@@ -4,11 +4,11 @@
 import numpy as np
 import pytest
 from flopy.utils.compare import eval_bud_diff
+
 from framework import TestFramework
-from simulation import TestSimulation
 
 paktest = "maw"
-ex = [f"ts_{paktest}01"]
+cases = [f"ts_{paktest}01"]
 
 
 def get_model(ws, name, timeseries=False):
@@ -16,7 +16,7 @@ def get_model(ws, name, timeseries=False):
     # temporal discretization
     nper = 1
     tdis_rc = []
-    for idx in range(nper):
+    for _ in range(nper):
         tdis_rc.append((1.0, 1, 1.0))
     ts_times = np.arange(0.0, 2.0, 1.0, dtype=float)
 
@@ -399,70 +399,65 @@ def get_model(ws, name, timeseries=False):
     return sim
 
 
-def build_model(idx, dir):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = get_model(ws, name)
 
     # build MODFLOW 6 files with timeseries
-    ws = os.path.join(dir, "mf6")
+    ws = os.path.join(test.workspace, "mf6")
     mc = get_model(ws, name, timeseries=True)
 
     return sim, mc
 
 
-def eval_model(sim):
-    print("evaluating model budgets...")
+def check_output(idx, test):
     # get ia/ja from binary grid file
-    fname = f"{os.path.basename(sim.name)}.dis.grb"
-    fpth = os.path.join(sim.simpath, fname)
+    fname = f"{os.path.basename(test.name)}.dis.grb"
+    fpth = os.path.join(test.workspace, fname)
     grbobj = flopy.mf6.utils.MfGrdFile(fpth)
     ia = grbobj._datadict["IA"] - 1
 
-    fname = f"{os.path.basename(sim.name)}.cbc"
+    fname = f"{os.path.basename(test.name)}.cbc"
 
     # open first gwf cbc file
-    fpth = os.path.join(sim.simpath, fname)
+    fpth = os.path.join(test.workspace, fname)
     cobj0 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # open second gwf cbc file
-    fpth = os.path.join(sim.simpath, "mf6", fname)
+    fpth = os.path.join(test.workspace, "mf6", fname)
     cobj1 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # define file path and evaluate difference
-    fname = f"{os.path.basename(sim.name)}.cbc.cmp.out"
-    fpth = os.path.join(sim.simpath, fname)
+    fname = f"{os.path.basename(test.name)}.cbc.cmp.out"
+    fpth = os.path.join(test.workspace, fname)
     eval_bud_diff(fpth, cobj0, cobj1, ia)
 
     # evaluate the sfr package budget file
-    fname = f"{os.path.basename(sim.name)}.{paktest}.cbc"
+    fname = f"{os.path.basename(test.name)}.{paktest}.cbc"
     # open first sfr cbc file
-    fpth = os.path.join(sim.simpath, fname)
+    fpth = os.path.join(test.workspace, fname)
     cobj0 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # open second sfr cbc file
-    fpth = os.path.join(sim.simpath, "mf6", fname)
+    fpth = os.path.join(test.workspace, "mf6", fname)
     cobj1 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # define file path and evaluate difference
-    fname = f"{os.path.basename(sim.name)}.{paktest}.cbc.cmp.out"
-    fpth = os.path.join(sim.simpath, fname)
+    fname = f"{os.path.basename(test.name)}.{paktest}.cbc.cmp.out"
+    fpth = os.path.join(test.workspace, fname)
     eval_bud_diff(fpth, cobj0, cobj1)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_ts_sfr01.py b/autotest/test_gwf_ts_sfr01.py
index adde4b870d4..1401b2da1ec 100644
--- a/autotest/test_gwf_ts_sfr01.py
+++ b/autotest/test_gwf_ts_sfr01.py
@@ -4,11 +4,11 @@
 import numpy as np
 import pytest
 from flopy.utils.compare import eval_bud_diff
+
 from framework import TestFramework
-from simulation import TestSimulation
 
 paktest = "sfr"
-ex = ["ts_sfr01"]
+cases = ["ts_sfr01"]
 
 
 def get_model(ws, name, timeseries=False):
@@ -16,7 +16,7 @@ def get_model(ws, name, timeseries=False):
     # temporal discretization
     nper = 1
     tdis_rc = []
-    for idx in range(nper):
+    for _ in range(nper):
         tdis_rc.append((1.0, 1, 1.0))
     ts_times = np.arange(0.0, 2.0, 1.0, dtype=float)
 
@@ -514,65 +514,63 @@ def get_model(ws, name, timeseries=False):
     return sim
 
 
-def build_model(idx, dir):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = get_model(ws, name)
 
     # build MODFLOW 6 files with timeseries
-    ws = os.path.join(dir, "mf6")
+    ws = os.path.join(test.workspace, "mf6")
     mc = get_model(ws, name, timeseries=True)
 
     return sim, mc
 
 
-def eval_model(sim):
-    print("evaluating model budgets...")
-
+def check_result(idx, test):
     # get ia/ja from binary grid file
-    fname = f"{os.path.basename(sim.name)}.dis.grb"
-    fpth = os.path.join(sim.simpath, fname)
+    fname = f"{os.path.basename(test.name)}.dis.grb"
+    fpth = os.path.join(test.workspace, fname)
     grbobj = flopy.mf6.utils.MfGrdFile(fpth)
     ia = grbobj._datadict["IA"] - 1
 
-    fname = f"{os.path.basename(sim.name)}.cbc"
+    fname = f"{os.path.basename(test.name)}.cbc"
 
     # open first gwf cbc file
-    fpth = os.path.join(sim.simpath, fname)
+    fpth = os.path.join(test.workspace, fname)
     cobj0 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # open second gwf cbc file
-    fpth = os.path.join(sim.simpath, "mf6", fname)
+    fpth = os.path.join(test.workspace, "mf6", fname)
     cobj1 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # define file path and evaluate difference
-    fname = f"{os.path.basename(sim.name)}.cbc.cmp.out"
-    fpth = os.path.join(sim.simpath, fname)
+    fname = f"{os.path.basename(test.name)}.cbc.cmp.out"
+    fpth = os.path.join(test.workspace, fname)
     eval_bud_diff(fpth, cobj0, cobj1, ia)
 
     # evaluate the sfr package budget file
-    fname = f"{os.path.basename(sim.name)}.{paktest}.cbc"
+    fname = f"{os.path.basename(test.name)}.{paktest}.cbc"
     # open first sfr cbc file
-    fpth = os.path.join(sim.simpath, fname)
+    fpth = os.path.join(test.workspace, fname)
     cobj0 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # open second sfr cbc file
-    fpth = os.path.join(sim.simpath, "mf6", fname)
+    fpth = os.path.join(test.workspace, "mf6", fname)
     cobj1 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # define file path and evaluate difference
-    fname = f"{os.path.basename(sim.name)}.{paktest}.cbc.cmp.out"
-    fpth = os.path.join(sim.simpath, fname)
+    fname = f"{os.path.basename(test.name)}.{paktest}.cbc.cmp.out"
+    fpth = os.path.join(test.workspace, fname)
     eval_bud_diff(fpth, cobj0, cobj1)
 
     # do some spot checks on the first sfr cbc file
     v0 = cobj0.get_data(totim=1.0, text="FLOW-JA-FACE")[0]
     q = []
-    for idx, node in enumerate(v0["node"]):
+    for i, node in enumerate(v0["node"]):
         if node > 5:
-            q.append(v0["q"][idx])
+            q.append(v0["q"][i])
     v0 = np.array(q)
     check = np.ones(v0.shape, dtype=float) * 5e-2
     check[-2] = 4e-2
@@ -594,17 +592,13 @@ def eval_model(sim):
     assert np.allclose(v0, check), "FROM-MVR failed"
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_result(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_ts_sfr02.py b/autotest/test_gwf_ts_sfr02.py
index 3a8442c86d0..7160f6279a8 100644
--- a/autotest/test_gwf_ts_sfr02.py
+++ b/autotest/test_gwf_ts_sfr02.py
@@ -4,11 +4,11 @@
 import numpy as np
 import pytest
 from flopy.utils.compare import eval_bud_diff
+
 from framework import TestFramework
-from simulation import TestSimulation
 
 paktest = "sfr"
-ex = ["ts_sfr02"]
+cases = ["ts_sfr02"]
 
 
 def get_model(ws, name, timeseries=False):
@@ -16,7 +16,7 @@ def get_model(ws, name, timeseries=False):
     # temporal discretization
     nper = 1
     tdis_rc = []
-    for idx in range(nper):
+    for _ in range(nper):
         tdis_rc.append((1.0, 1, 1.0))
     ts_times = np.arange(0.0, 2.0, 1.0, dtype=float)
 
@@ -505,57 +505,55 @@ def get_model(ws, name, timeseries=False):
     return sim
 
 
-def build_model(idx, dir):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = get_model(ws, name)
 
     # build MODFLOW 6 files with timeseries
-    ws = os.path.join(dir, "mf6")
+    ws = os.path.join(test.workspace, "mf6")
     mc = get_model(ws, name, timeseries=True)
 
     return sim, mc
 
 
-def eval_model(sim):
-    print("evaluating model budgets...")
-
+def check_output(idx, test):
     # get ia/ja from binary grid file
-    fname = f"{os.path.basename(sim.name)}.dis.grb"
-    fpth = os.path.join(sim.simpath, fname)
+    fname = f"{os.path.basename(test.name)}.dis.grb"
+    fpth = os.path.join(test.workspace, fname)
     grbobj = flopy.mf6.utils.MfGrdFile(fpth)
     ia = grbobj._datadict["IA"] - 1
 
-    fname = f"{os.path.basename(sim.name)}.cbc"
+    fname = f"{os.path.basename(test.name)}.cbc"
 
     # open first gwf cbc file
-    fpth = os.path.join(sim.simpath, fname)
+    fpth = os.path.join(test.workspace, fname)
     cobj0 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # open second gwf cbc file
-    fpth = os.path.join(sim.simpath, "mf6", fname)
+    fpth = os.path.join(test.workspace, "mf6", fname)
     cobj1 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # define file path and evaluate difference
-    fname = f"{os.path.basename(sim.name)}.cbc.cmp.out"
-    fpth = os.path.join(sim.simpath, fname)
+    fname = f"{os.path.basename(test.name)}.cbc.cmp.out"
+    fpth = os.path.join(test.workspace, fname)
     eval_bud_diff(fpth, cobj0, cobj1, ia)
 
     # evaluate the sfr package budget file
-    fname = f"{os.path.basename(sim.name)}.{paktest}.cbc"
+    fname = f"{os.path.basename(test.name)}.{paktest}.cbc"
     # open first sfr cbc file
-    fpth = os.path.join(sim.simpath, fname)
+    fpth = os.path.join(test.workspace, fname)
     cobj0 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # open second sfr cbc file
-    fpth = os.path.join(sim.simpath, "mf6", fname)
+    fpth = os.path.join(test.workspace, "mf6", fname)
     cobj1 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # define file path and evaluate difference
-    fname = f"{os.path.basename(sim.name)}.{paktest}.cbc.cmp.out"
-    fpth = os.path.join(sim.simpath, fname)
+    fname = f"{os.path.basename(test.name)}.{paktest}.cbc.cmp.out"
+    fpth = os.path.join(test.workspace, fname)
     eval_bud_diff(fpth, cobj0, cobj1)
 
     # do some spot checks on the first sfr cbc file
@@ -563,9 +561,9 @@ def eval_model(sim):
     # FLOW-JA-FACE
     v0 = cobj0.get_data(totim=1.0, text="FLOW-JA-FACE")[0]
     q = []
-    for idx, node in enumerate(v0["node"]):
+    for i, node in enumerate(v0["node"]):
         if node in nodes:
-            q.append(v0["q"][idx])
+            q.append(v0["q"][i])
     v0 = np.array(q)
     check = np.ones(v0.shape, dtype=float) * 5e-2
     check[1] = 0.76743
@@ -574,43 +572,39 @@ def eval_model(sim):
 
     v0 = cobj0.get_data(totim=1.0, text="EXT-OUTFLOW")[0]
     q = []
-    for idx, node in enumerate(v0["node"]):
+    for i, node in enumerate(v0["node"]):
         if node in nodes:
-            q.append(v0["q"][idx])
+            q.append(v0["q"][i])
     v0 = np.array(q)
     check = np.array([-2.5e-2, -0.80871, -5e-2, -5e-2, -2.0e-2, -5e-2])
     assert np.allclose(v0, check), "EXT-OUTFLOW failed"
 
     v0 = cobj0.get_data(totim=1.0, text="FROM-MVR")[0]
     q = []
-    for idx, node in enumerate(v0["node"]):
+    for i, node in enumerate(v0["node"]):
         if node in nodes:
-            q.append(v0["q"][idx])
+            q.append(v0["q"][i])
     v0 = np.array(q)
     check = np.array([0.0, 4.5e-2, 0.0, 0.0, 0.0, 0.0])
     assert np.allclose(v0, check), "FROM-MVR failed"
 
     v0 = cobj0.get_data(totim=1.0, text="TO-MVR")[0]
     q = []
-    for idx, node in enumerate(v0["node"]):
+    for i, node in enumerate(v0["node"]):
         if node in nodes:
-            q.append(v0["q"][idx])
+            q.append(v0["q"][i])
     v0 = np.array(q)
     check = np.array([-2.5e-2, 0.0, 0.0, 0.0, -2.0e-2, 0.0])
     assert np.allclose(v0, check), "TO-MVR failed"
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_ts_uzf01.py b/autotest/test_gwf_ts_uzf01.py
index 4af7b20511f..5434bb2c165 100644
--- a/autotest/test_gwf_ts_uzf01.py
+++ b/autotest/test_gwf_ts_uzf01.py
@@ -4,11 +4,11 @@
 import numpy as np
 import pytest
 from flopy.utils.compare import eval_bud_diff
+
 from framework import TestFramework
-from simulation import TestSimulation
 
 paktest = "uzf"
-ex = ["ts_uzf01"]
+cases = ["ts_uzf01"]
 
 
 def get_model(ws, name, timeseries=False):
@@ -16,7 +16,7 @@ def get_model(ws, name, timeseries=False):
     # temporal discretization
     nper = 1
     tdis_rc = []
-    for idx in range(nper):
+    for _ in range(nper):
         tdis_rc.append((1.0, 1, 1.0))
     ts_times = np.arange(0.0, 2.0, 1.0, dtype=float)
 
@@ -414,7 +414,12 @@ def get_model(ws, name, timeseries=False):
         (7, (0, 7, 2), 1, -1, 1.0, kv, 0.2, 0.4, 0.3, 3.5),
         (8, (0, 7, 3), 1, -1, 1.0, kv, 0.2, 0.4, 0.3, 3.5),
     ]
-    finf, pet, extdp, extwc, = (
+    (
+        finf,
+        pet,
+        extdp,
+        extwc,
+    ) = (
         1e-8,
         5e-9,
         1.0,
@@ -632,71 +637,65 @@ def get_model(ws, name, timeseries=False):
     return sim
 
 
-def build_model(idx, dir):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = get_model(ws, name)
 
     # build MODFLOW 6 files with timeseries
-    ws = os.path.join(dir, "mf6")
+    ws = os.path.join(test.workspace, "mf6")
     mc = get_model(ws, name, timeseries=True)
 
     return sim, mc
 
 
-def eval_model(sim):
-    print("evaluating model budgets...")
-
+def check_output(idx, test):
     # get ia/ja from binary grid file
-    fname = f"{os.path.basename(sim.name)}.dis.grb"
-    fpth = os.path.join(sim.simpath, fname)
+    fname = f"{os.path.basename(test.name)}.dis.grb"
+    fpth = os.path.join(test.workspace, fname)
     grbobj = flopy.mf6.utils.MfGrdFile(fpth)
     ia = grbobj._datadict["IA"] - 1
 
-    fname = f"{os.path.basename(sim.name)}.cbc"
+    fname = f"{os.path.basename(test.name)}.cbc"
 
     # open first gwf cbc file
-    fpth = os.path.join(sim.simpath, fname)
+    fpth = os.path.join(test.workspace, fname)
     cobj0 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # open second gwf cbc file
-    fpth = os.path.join(sim.simpath, "mf6", fname)
+    fpth = os.path.join(test.workspace, "mf6", fname)
     cobj1 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # define file path and evaluate difference
-    fname = f"{os.path.basename(sim.name)}.cbc.cmp.out"
-    fpth = os.path.join(sim.simpath, fname)
+    fname = f"{os.path.basename(test.name)}.cbc.cmp.out"
+    fpth = os.path.join(test.workspace, fname)
     eval_bud_diff(fpth, cobj0, cobj1, ia)
 
     # evaluate the sfr package budget file
-    fname = f"{os.path.basename(sim.name)}.{paktest}.cbc"
+    fname = f"{os.path.basename(test.name)}.{paktest}.cbc"
     # open first sfr cbc file
-    fpth = os.path.join(sim.simpath, fname)
+    fpth = os.path.join(test.workspace, fname)
     cobj0 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # open second sfr cbc file
-    fpth = os.path.join(sim.simpath, "mf6", fname)
+    fpth = os.path.join(test.workspace, "mf6", fname)
     cobj1 = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # define file path and evaluate difference
-    fname = f"{os.path.basename(sim.name)}.{paktest}.cbc.cmp.out"
-    fpth = os.path.join(sim.simpath, fname)
+    fname = f"{os.path.basename(test.name)}.{paktest}.cbc.cmp.out"
+    fpth = os.path.join(test.workspace, fname)
     eval_bud_diff(fpth, cobj0, cobj1)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_utl01_binaryinput.py b/autotest/test_gwf_utl01_binaryinput.py
index a7ef3faef37..ad5df3aa573 100644
--- a/autotest/test_gwf_utl01_binaryinput.py
+++ b/autotest/test_gwf_utl01_binaryinput.py
@@ -1,20 +1,21 @@
-# test reading of binary initial heads (float) and also binary icelltype (int).
-# 1. Have binary data in a separate record for each layer
-# 2. Have binary data in a single record for all layers
+"""
+Test reading of binary initial heads (float) and also binary icelltype (int).
+1. Have binary data in a separate record for each layer
+2. Have binary data in a single record for all layers
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["binary01", "binary02"]
+from framework import TestFramework
 
+cases = ["binary01", "binary02"]
 
-def build_model(idx, dir):
 
+def build_models(idx, test):
     nlay, nrow, ncol = 5, 6, 7
     nper = 1
     perlen = 1.0
@@ -32,13 +33,13 @@ def build_model(idx, dir):
     hclose, rclose, relax = 1e-6, 1e-3, 1.0
 
     tdis_rc = []
-    for i in range(nper):
+    for _ in range(nper):
         tdis_rc.append((perlen, nstp, tsmult))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -76,7 +77,7 @@ def build_model(idx, dir):
     # write top to a binary file
     text = "TOP"
     fname = "top.bin"
-    pth = os.path.join(dir, fname)
+    pth = os.path.join(test.workspace, fname)
     f = open(pth, "wb")
     header = flopy.utils.BinaryHeader.create(
         bintype="HEAD",
@@ -111,7 +112,7 @@ def build_model(idx, dir):
         for k in range(nlay):
             text = f"BOTM_L{k + 1}"
             fname = f"botm.l{k + 1:02d}.bin"
-            pth = os.path.join(dir, fname)
+            pth = os.path.join(test.workspace, fname)
             f = open(pth, "wb")
             header = flopy.utils.BinaryHeader.create(
                 bintype="HEAD",
@@ -143,7 +144,7 @@ def build_model(idx, dir):
             )
     elif idx == 1:
         fname = "botm.bin"
-        pth = os.path.join(dir, fname)
+        pth = os.path.join(test.workspace, fname)
         f = open(pth, "wb")
         tarr = np.ones((nlay, nrow, ncol), dtype=np.float64)
         for k in range(nlay):
@@ -177,7 +178,7 @@ def build_model(idx, dir):
         for k in range(nlay):
             text = f"IDOMAIN_L{k + 1}"
             fname = f"idomain.l{k + 1:02d}.bin"
-            pth = os.path.join(dir, fname)
+            pth = os.path.join(test.workspace, fname)
             f = open(pth, "wb")
             header = flopy.utils.BinaryHeader.create(
                 bintype="HEAD",
@@ -209,7 +210,7 @@ def build_model(idx, dir):
             )
     elif idx == 1:
         fname = "idomain.bin"
-        pth = os.path.join(dir, fname)
+        pth = os.path.join(test.workspace, fname)
         f = open(pth, "wb")
         header = flopy.utils.BinaryHeader.create(
             bintype="HEAD",
@@ -258,7 +259,7 @@ def build_model(idx, dir):
         for k in range(nlay):
             text = f"IC_L{k + 1}"
             fname = f"ic.strt_l{k + 1:02d}.bin"
-            pth = os.path.join(dir, fname)
+            pth = os.path.join(test.workspace, fname)
             f = open(pth, "wb")
             header = flopy.utils.BinaryHeader.create(
                 bintype="HEAD",
@@ -290,7 +291,7 @@ def build_model(idx, dir):
             )
     elif idx == 1:
         fname = "ic.strt.bin"
-        pth = os.path.join(dir, fname)
+        pth = os.path.join(test.workspace, fname)
         f = open(pth, "wb")
         header = flopy.utils.BinaryHeader.create(
             bintype="HEAD",
@@ -327,7 +328,7 @@ def build_model(idx, dir):
         icelltype = []
         for k in range(nlay):
             fname = f"npf.icelltype.l{k + 1}.bin"
-            pth = os.path.join(dir, fname)
+            pth = os.path.join(test.workspace, fname)
             f = open(pth, "wb")
             header = flopy.utils.BinaryHeader.create(
                 bintype="head",
@@ -360,7 +361,7 @@ def build_model(idx, dir):
             )
     elif idx == 1:
         fname = "npf.icelltype.bin"
-        pth = os.path.join(dir, fname)
+        pth = os.path.join(test.workspace, fname)
         f = open(pth, "wb")
         header = flopy.utils.BinaryHeader.create(
             bintype="head",
@@ -427,12 +428,12 @@ def build_model(idx, dir):
     return sim, None
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(TestSimulation(name=name, exe_dict=targets), ws)
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        targets=targets,
+    )
+    test.run()
diff --git a/autotest/test_gwf_utl02_timeseries.py b/autotest/test_gwf_utl02_timeseries.py
index 3f06e46042a..cc37b394d5a 100644
--- a/autotest/test_gwf_utl02_timeseries.py
+++ b/autotest/test_gwf_utl02_timeseries.py
@@ -1,13 +1,12 @@
 import flopy
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["ts01"]
+from framework import TestFramework
 
+cases = ["ts01"]
 
-def build_model(idx, dir):
 
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 3, 3
     nper = 2
     perlen = [1.0, 14966]
@@ -26,10 +25,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp, tsmult))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -148,12 +147,12 @@ def build_model(idx, dir):
     return sim, None
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(TestSimulation(name=name, exe_dict=targets), ws)
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        targets=targets,
+    )
+    test.run()
diff --git a/autotest/test_gwf_utl03_obs01.py b/autotest/test_gwf_utl03_obs01.py
index a8df98865b0..85f0c504b5b 100644
--- a/autotest/test_gwf_utl03_obs01.py
+++ b/autotest/test_gwf_utl03_obs01.py
@@ -3,10 +3,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["utl03_obs"]
+cases = ["utl03_obs"]
 
 # temporal discretization
 nper = 2
@@ -48,13 +48,11 @@
 hclose, rclose, relax = 1e-6, 0.01, 1.0
 
 
-def build_mf6(idx, ws, exe, binaryobs=True):
-    name = ex[idx]
+def build_mf6(idx, ws, binaryobs=True):
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name=exe, sim_ws=ws
-    )
+    sim = flopy.mf6.MFSimulation(sim_name=name, version="mf6", sim_ws=ws)
     # create tdis package
     flopy.mf6.ModflowTdis(
         sim, time_units="DAYS", nper=nper, perioddata=tdis_rc
@@ -137,14 +135,14 @@ def build_mf6(idx, ws, exe, binaryobs=True):
     return sim
 
 
-def build_model(idx, dir, exe):
+def build_model(idx, dir):
     ws = dir
     # build mf6 with ascii observation output
-    sim = build_mf6(idx, ws, exe=exe, binaryobs=False)
+    sim = build_mf6(idx, ws, binaryobs=False)
 
     # build mf6 with binary observation output
     wsc = os.path.join(ws, "mf6")
-    mc = build_mf6(idx, wsc, exe=exe, binaryobs=True)
+    mc = build_mf6(idx, wsc, binaryobs=True)
 
     sim.write_simulation()
     mc.write_simulation()
@@ -153,16 +151,16 @@ def build_model(idx, dir, exe):
     return sim, mc
 
 
-def build_models(dir, exe):
-    for idx, name in enumerate(ex):
-        sim, mc = build_model(idx, dir, exe)
-        sim.write_simulation()
-        mc.write_simulation()
-        hack_binary_obs(idx, dir)
+def build_models(idx, test):
+    sim, mc = build_model(idx, test.workspace)
+    sim.write_simulation()
+    mc.write_simulation()
+    hack_binary_obs(idx, test.workspace)
+    return sim, mc
 
 
 def hack_binary_obs(idx, dir):
-    name = ex[idx]
+    name = cases[idx]
     ws = dir
     wsc = os.path.join(ws, "mf6")
     fname = name + ".obs"
@@ -176,14 +174,11 @@ def hack_binary_obs(idx, dir):
                 line += "  BINARY"
             f.write(f"{line}\n")
         f.close()
-    return
-
 
-def eval_obs(sim):
-    print("evaluating observations...")
 
+def check_output(idx, test):
     # get results from the observation files
-    pth = sim.simpath
+    pth = test.workspace
     files = [fn for fn in os.listdir(pth) if ".csv" in fn]
     for file in files:
         pth0 = os.path.join(pth, file)
@@ -216,13 +211,14 @@ def eval_obs(sim):
             assert np.allclose(d0[name], d1[name], rtol=1e-5), msg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    mf6 = targets["mf6"]
-    test = TestFramework()
-    build_models(ws, mf6)
-    test.run(TestSimulation(name=name, exe_dict=targets, exfunc=eval_obs), ws)
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
+        overwrite=False,
+    )
+    test.run()
diff --git a/autotest/test_gwf_utl04_auxmult.py b/autotest/test_gwf_utl04_auxmult.py
index 78ae0f8f55d..29ba94c2200 100644
--- a/autotest/test_gwf_utl04_auxmult.py
+++ b/autotest/test_gwf_utl04_auxmult.py
@@ -1,7 +1,5 @@
 """
-MODFLOW 6 Autotest
 Test to make sure that auxmultcol is working when used with a time series
-
 """
 
 import os
@@ -9,14 +7,18 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["auxmult01"]
+from framework import TestFramework
 
+cases = ["auxmult01", "auxmult02"]
 
-def build_model(idx, dir):
+wellist = [
+    [(0, 2, 2), "tsq", "tsqfact"],
+    [(0, 2, 2), 1.0000000, "tsqfact"]
+]
 
+def build_models(idx, test):
+    global numstep
     nlay, nrow, ncol = 1, 3, 3
     perlen = [1.0, 1.0, 1.0, 1.0]
     nstp = [10, 1, 1, 1]
@@ -26,6 +28,7 @@ def build_model(idx, dir):
     delr = delc = lenx / float(nrow)
     botm = -1.0
     hk = 1.0
+    numstep = sum(nstp)
 
     nouter, ninner = 100, 300
     hclose, rclose, relax = 1e-6, 1e-3, 1.0
@@ -34,10 +37,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -105,19 +108,28 @@ def build_model(idx, dir):
     )
 
     # wel files
-    wellist1 = []
-    wellist1.append([(0, 2, 2), "tsq", "tsqfact"])
     wel = flopy.mf6.ModflowGwfwel(
         gwf,
         pname="wel",
         print_input=True,
         print_flows=True,
-        stress_period_data={0: wellist1},
+        stress_period_data={0: [wellist[idx]]},
         auxiliary=["auxmult"],
         auxmultname="auxmult",
     )
     # ts_filerecord='well-rates.ts')
 
+    # wel obs
+    obs = {
+        "wel.obs.csv": [
+            ["q", "wel", (0, 2, 2)]
+        ],
+    }
+    welobs = wel.obs.initialize(
+        print_input=True,
+        continuous=obs,
+    )
+
     # well ts package
     ts_recarray = [
         (0.0, 0.0, 1.0),
@@ -160,10 +172,9 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
-    fpth = os.path.join(sim.simpath, "auxmult01.bud")
+def check_output(idx, test):
+    name = cases[idx]
+    fpth = os.path.join(test.workspace, f"{name}.bud")
     bobj = flopy.utils.CellBudgetFile(fpth, precision="double", verbose=False)
     records = bobj.get_data(text="wel")
 
@@ -177,17 +188,26 @@ def eval_model(sim):
     msg = f"err {qlist} /= {answer}"
     assert np.allclose(qlist, answer), msg
 
-    # assert False
+    # MODFLOW 6 observations
+    fpth = os.path.join(test.workspace, "wel.obs.csv")
+    try:
+        obs = np.genfromtxt(fpth, names=True, delimiter=",")
+    except:
+        assert False, f'could not load data from "{fpth}"'
+
+    rate = obs["Q"]
+    obs_answer = [1.0 if x%2==0 else 0.0 for x in range(numstep)]
+    msg = f"err {rate} /= {obs_answer}"
+    assert np.allclose(rate, obs_answer), msg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(name=name, exe_dict=targets, exfunc=eval_model), ws
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_utl05_budparse.py b/autotest/test_gwf_utl05_budparse.py
index 216413bf199..99001a76ab3 100644
--- a/autotest/test_gwf_utl05_budparse.py
+++ b/autotest/test_gwf_utl05_budparse.py
@@ -1,6 +1,5 @@
 """
 Test of budget table parsing
-
 """
 
 import os
@@ -8,18 +7,17 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["gwf_utl05"]
+cases = ["gwf_utl05"]
 laytyp = [1]
 ss = [1.0e-10]
 sy = [0.1]
 nlay, nrow, ncol = 1, 1, 1
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     nper = 2
     perlen = [2.0, 2.0]
     nstp = [14, 14]
@@ -35,13 +33,13 @@ def build_model(idx, dir):
     hclose, rclose, relax = 1e-6, 1e-6, 0.97
 
     tdis_rc = []
-    for id in range(nper):
-        tdis_rc.append((perlen[id], nstp[id], tsmult[id]))
+    for i in range(nper):
+        tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -141,13 +139,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_flow(sim):
-    print("evaluating flow...")
-
-    gwfname = "gwf_" + sim.name
+def check_output(idx, test):
+    gwfname = "gwf_" + test.name
 
     # This will fail if budget numbers cannot be read
-    fpth = os.path.join(sim.simpath, f"{gwfname}.lst")
+    fpth = os.path.join(test.workspace, f"{gwfname}.lst")
     mflist = flopy.utils.Mf6ListBudget(fpth)
     names = mflist.get_record_names()
     print(names)
@@ -159,17 +155,13 @@ def eval_flow(sim):
     assert np.allclose(inc["WEL_OUT"], 0.0)
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_flow, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_utl06_tas.py b/autotest/test_gwf_utl06_tas.py
index dbde41bec9a..17ca4fc279e 100644
--- a/autotest/test_gwf_utl06_tas.py
+++ b/autotest/test_gwf_utl06_tas.py
@@ -1,7 +1,5 @@
 """
-MODFLOW 6 Autotest
 Test the time array series for the recharge package
-
 """
 
 import os
@@ -9,10 +7,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = [
+cases = [
     "utl06_tas_a",
     "utl06_tas_b",
     "utl06_tas_c",
@@ -31,7 +29,7 @@
 idomain[0, :, :] = np.array(idomain_lay0)
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     perlen = [5.0]
     nstp = [5]
     tsmult = [1.0]
@@ -54,7 +52,7 @@ def build_model(idx, dir):
     sim_name = "sim"
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=sim_name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -190,14 +188,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
+def check_output(idx, test):
     gwfname = "gwf"
-    idx = sim.idxsim
 
     # load concentration file
-    fpth = os.path.join(sim.simpath, f"{gwfname}.hds")
+    fpth = os.path.join(test.workspace, f"{gwfname}.hds")
     try:
         hobj = flopy.utils.HeadFile(fpth, precision="double")
         head = hobj.get_data()
@@ -205,7 +200,7 @@ def eval_transport(sim):
         assert False, f'could not load data from "{fpth}"'
 
     # load gwf budget file
-    fpth = os.path.join(sim.simpath, f"{gwfname}.cbc")
+    fpth = os.path.join(test.workspace, f"{gwfname}.cbc")
     try:
         bobj = flopy.utils.CellBudgetFile(
             fpth,
@@ -365,17 +360,13 @@ def eval_transport(sim):
         assert np.allclose(q, qa), f"{q} /=\n {qa}"
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_uzf01.py b/autotest/test_gwf_uzf01.py
index 0d168da3265..d269ab11f01 100644
--- a/autotest/test_gwf_uzf01.py
+++ b/autotest/test_gwf_uzf01.py
@@ -1,7 +1,6 @@
 """
-# Test the ability of a uzf to route waves through a simple 1d vertical
-# column.
-
+Test the ability of a uzf to route waves through a simple 1d vertical
+column.
 """
 
 import os
@@ -9,16 +8,15 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["gwf_uzf01a"]
+cases = ["gwf_uzf01a"]
 nlay, nrow, ncol = 100, 1, 1
 
 
-def build_model(idx, exdir):
-
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
 
     perlen = [500.0]
     nper = len(perlen)
@@ -36,11 +34,11 @@ def build_model(idx, exdir):
     sy = 0.1
 
     tdis_rc = []
-    for idx in range(nper):
-        tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+    for i in range(nper):
+        tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
     # build MODFLOW 6 files
-    ws = exdir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -213,11 +211,9 @@ def build_model(idx, exdir):
     return sim, None
 
 
-def eval_flow(sim):
-    print("evaluating flow...")
-
-    name = sim.name
-    ws = sim.simpath
+def check_output(idx, test):
+    name = test.name
+    ws = test.workspace
 
     # check binary grid file
     fname = os.path.join(ws, name + ".dis.grb")
@@ -255,24 +251,20 @@ def eval_flow(sim):
         names[-1]: obs_obj.get_data(obsname=names[-1]),
     }
     cbc = uobj.get_ts(idx=[[0, 0, 1], [0, 0, 49]], text="GWF")
-    for idx, key in enumerate(obs.keys()):
-        assert np.allclose(obs[key][key], -cbc[:, idx + 1]), (
+    for i, key in enumerate(obs.keys()):
+        assert np.allclose(obs[key][key], -cbc[:, i + 1]), (
             f"observation data for {key} is not the same as "
             "data in the cell-by-cell file."
         )
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_flow, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_uzf02.py b/autotest/test_gwf_uzf02.py
index 03996c8efe6..57d40316d9f 100644
--- a/autotest/test_gwf_uzf02.py
+++ b/autotest/test_gwf_uzf02.py
@@ -1,6 +1,5 @@
 """
-# Test uzf for the vs2d comparison problem in the uzf documentation
-
+Test uzf for the vs2d comparison problem in the uzf documentation
 """
 
 import os
@@ -8,15 +7,14 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["gwf_uzf02a"]
+cases = ["gwf_uzf02a"]
 nlay, nrow, ncol = 1, 1, 1
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     perlen = [17.7]
     nper = len(perlen)
     nstp = [177]
@@ -46,10 +44,10 @@ def build_model(idx, dir):
     for id in range(nper):
         tdis_rc.append((perlen[id], nstp[id], tsmult[id]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -230,10 +228,10 @@ def make_plot(sim, obsvals):
 
     # shows curves for times 2.5, 7.5, 12.6, 17.7
     # which are indices 24, 74, 125, and -1
-    idx = [24, 74, 125, -1]
+    indices = [24, 74, 125, -1]
 
     obsvals = [list(row) for row in obsvals]
-    obsvals = [obsvals[i] for i in idx]
+    obsvals = [obsvals[i] for i in indices]
     obsvals = np.array(obsvals)
 
     import matplotlib.pyplot as plt
@@ -253,15 +251,13 @@ def make_plot(sim, obsvals):
     plt.legend()
 
     fname = "fig-xsect.pdf"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(sim.workspace, fname)
     plt.savefig(fname, bbox_inches="tight")
 
 
-def eval_flow(sim):
-    print("evaluating flow...")
-
-    name = sim.name
-    ws = sim.simpath
+def check_output(idx, test):
+    name = test.name
+    ws = test.workspace
 
     # check binary grid file
     fname = os.path.join(ws, name + ".dis.grb")
@@ -298,26 +294,21 @@ def eval_flow(sim):
         assert np.allclose(uz["q"], uz_answer), "unsat ET is not correct"
 
     # Make plot of obs
-    fpth = os.path.join(sim.simpath, name + ".uzf.obs.csv")
+    fpth = os.path.join(test.workspace, name + ".uzf.obs.csv")
     try:
         obsvals = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
         assert False, f'could not load data from "{fpth}"'
-    if False:
-        make_plot(sim, obsvals)
-
-
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_flow, idxsim=0
-        ),
-        ws,
+    # make_plot(sim, obsvals)
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_uzf03.py b/autotest/test_gwf_uzf03.py
index 361036a4c01..77c5e8c76a1 100644
--- a/autotest/test_gwf_uzf03.py
+++ b/autotest/test_gwf_uzf03.py
@@ -1,7 +1,6 @@
 """
-# Test uzf for the vs2d comparison problem in the uzf documentation except in
-# this case there are 15 gwf and uzf cells, rather than just one cell.
-
+Test uzf for the vs2d comparison problem in the uzf documentation except in
+this case there are 15 gwf and uzf cells, rather than just one cell.
 """
 
 import os
@@ -9,14 +8,14 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["gwf_uzf03a"]
+cases = ["gwf_uzf03a"]
 nlay, nrow, ncol = 15, 1, 1
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     perlen = [17.7]
     nper = len(perlen)
     nstp = [177]
@@ -46,10 +45,10 @@ def build_model(idx, dir):
     for id in range(nper):
         tdis_rc.append((perlen[id], nstp[id], tsmult[id]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -231,10 +230,10 @@ def make_plot(sim, obsvals):
 
     # shows curves for times 2.5, 7.5, 12.6, 17.7
     # which are indices 24, 74, 125, and -1
-    idx = [24, 74, 125, -1]
+    indices = [24, 74, 125, -1]
 
     obsvals = [list(row) for row in obsvals]
-    obsvals = [obsvals[i] for i in idx]
+    obsvals = [obsvals[i] for i in indices]
     obsvals = np.array(obsvals)
 
     import matplotlib.pyplot as plt
@@ -253,15 +252,13 @@ def make_plot(sim, obsvals):
     plt.legend()
 
     fname = "fig-xsect.pdf"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(sim.workspace, fname)
     plt.savefig(fname, bbox_inches="tight")
 
 
-def eval_flow(sim):
-    print("evaluating flow...")
-
-    name = sim.name
-    ws = sim.simpath
+def check_output(idx, test):
+    name = test.name
+    ws = test.workspace
 
     # check binary grid file
     fname = os.path.join(ws, name + ".dis.grb")
@@ -298,26 +295,21 @@ def eval_flow(sim):
         assert np.allclose(uz["q"], uz_answer), "unsat ET is not correct"
 
     # Make plot of obs
-    fpth = os.path.join(sim.simpath, name + ".uzf.obs.csv")
+    fpth = os.path.join(test.workspace, name + ".uzf.obs.csv")
     try:
         obsvals = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
         assert False, f'could not load data from "{fpth}"'
-    if False:
-        make_plot(sim, obsvals)
-
-
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_flow, idxsim=0
-        ),
-        ws,
+    # make_plot(test, obsvals)
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_uzf04.py b/autotest/test_gwf_uzf04.py
index 4662ea98e2d..b53cf7627db 100644
--- a/autotest/test_gwf_uzf04.py
+++ b/autotest/test_gwf_uzf04.py
@@ -1,12 +1,11 @@
 """
-# Test uzf mass balance.  One cell model with starting water table at -20
-# and GHB with stage of -25.  Uzf infiltration is applied, but water table
-# still falls.  This test looks at the simulated unsat zone storage and
-# unsat volume (stored as an auxiliary variable) and compares the results
-# to calculated values.  Although the Uzf unsat storage and unsat volume
-# should probably be for total water instead of just mobile water (theta -
-# thetar), this is not how Uzf was designed.
-
+Test uzf mass balance.  One cell model with starting water table at -20
+and GHB with stage of -25.  Uzf infiltration is applied, but water table
+still falls.  This test looks at the simulated unsat zone storage and
+unsat volume (stored as an auxiliary variable) and compares the results
+to calculated values.  Although the Uzf unsat storage and unsat volume
+should probably be for total water instead of just mobile water (theta -
+thetar), this is not how Uzf was designed.
 """
 
 import os
@@ -14,10 +13,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["gwf_uzf04a"]
+cases = ["gwf_uzf04a"]
 nlay, nrow, ncol = 1, 1, 1
 thts = 0.30  # saturated water content
 thtr = 0.05  # residual water content
@@ -25,8 +24,7 @@
 strt = -20.0
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     perlen = [1.0]
     nper = len(perlen)
     nstp = [1]
@@ -51,10 +49,10 @@ def build_model(idx, dir):
     for id in range(nper):
         tdis_rc.append((perlen[id], nstp[id], tsmult[id]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -215,11 +213,9 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_flow(sim):
-    print("evaluating flow...")
-
-    name = sim.name
-    ws = sim.simpath
+def check_output(idx, test):
+    name = test.name
+    ws = test.workspace
 
     fname = os.path.join(ws, f"{name}.uzf.bin")
     wobj = flopy.utils.HeadFile(fname, text="WATER-CONTENT")
@@ -257,17 +253,13 @@ def eval_flow(sim):
     ), "Simulated mobile water volume in aux does not match known result"
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_flow, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_uzf05.py b/autotest/test_gwf_uzf05.py
index 457ffd8b7b8..4393f4f43e9 100644
--- a/autotest/test_gwf_uzf05.py
+++ b/autotest/test_gwf_uzf05.py
@@ -2,7 +2,6 @@
 Test uzf for case where uzf is only in top cell.  There was a
 bug with this in the past in which case UZF would not send
 water to water table unless there was a uzf in each cell.
-
 """
 
 import os
@@ -10,10 +9,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["gwf_uzf05a"]
+cases = ["gwf_uzf05a"]
 nlay, nrow, ncol = 3, 1, 1
 
 thts = 0.30  # saturated water content
@@ -22,8 +21,7 @@
 strt = 15.0
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     perlen = [1.0]
     nper = len(perlen)
     nstp = [1]
@@ -48,10 +46,10 @@ def build_model(idx, dir):
     for id in range(nper):
         tdis_rc.append((perlen[id], nstp[id], tsmult[id]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -214,11 +212,9 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_flow(sim):
-    print("evaluating flow...")
-
-    name = sim.name
-    ws = sim.simpath
+def check_output(idx, test):
+    name = test.name
+    ws = test.workspace
 
     fname = os.path.join(ws, f"{name}.uzf.bin")
     wobj = flopy.utils.HeadFile(fname, text="WATER-CONTENT")
@@ -239,17 +235,13 @@ def eval_flow(sim):
     assert np.isclose(q, -4.0), "Flow from UZF to node 1 should be -4."
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_flow, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_uzf_gwet.py b/autotest/test_gwf_uzf_gwet.py
index ab7d74556d8..6c11c55e90e 100644
--- a/autotest/test_gwf_uzf_gwet.py
+++ b/autotest/test_gwf_uzf_gwet.py
@@ -3,16 +3,19 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["uzf_3lay"]
+cases = ["uzf_3lay"]
+name = "model"
 iuz_cell_dict = {}
 cell_iuz_dict = {}
 
+nouter, ninner = 100, 300
+hclose, rclose, relax = 1e-9, 1e-3, 0.97
 
-def build_model(idx, dir):
 
+def build_models(idx, test):
     nlay, nrow, ncol = 3, 1, 10
     nper = 5
     perlen = [20.0, 20.0, 20.0, 500.0, 2000.0]
@@ -23,17 +26,12 @@ def build_model(idx, dir):
     delc = 1.0
     strt = -25
 
-    nouter, ninner = 100, 300
-    hclose, rclose, relax = 1e-9, 1e-3, 0.97
-
     tdis_rc = []
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
-
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -98,7 +96,7 @@ def build_model(idx, dir):
     )
 
     # transient uzf info
-    # iuzno  cellid landflg ivertcn surfdp vks thtr thts thti eps [bndnm]
+    # ifno  cellid landflg ivertcn surfdp vks thtr thts thti eps [bndnm]
     uzf_pkdat = [
         [0, (0, 0, 1), 1, 8, 1, 1, 0.05, 0.35, 0.05, 4, "uzf01"],
         [1, (0, 0, 2), 1, 9, 1, 1, 0.05, 0.35, 0.05, 4, "uzf02"],
@@ -257,17 +255,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_model(sim):
-    print("evaluating model...")
+def check_output(idx, test):
+    ws = test.workspace
+    test = flopy.mf6.MFSimulation.load(sim_ws=ws)
 
-    ws = sim.simpath
-    sim = flopy.mf6.MFSimulation.load(sim_ws=ws)
-
-    fpth = os.path.join(ws, "uzf_3lay.hds")
-    hobj = flopy.utils.HeadFile(fpth, precision="double")
-    hds = hobj.get_alldata()
-
-    bpth = os.path.join(ws, "uzf_3lay.cbc")
+    bpth = ws / f"{name}.cbc"
     bobj = flopy.utils.CellBudgetFile(bpth, precision="double")
     bobj.get_unique_record_names()
     # '          STO-SS'
@@ -281,7 +273,7 @@ def eval_model(sim):
     gwet = bobj.get_data(text="UZF-GWET")
     gwet = np.array(gwet)
 
-    uzpth = os.path.join(ws, "uzf_3lay.uzf.bud")
+    uzpth = os.path.join(ws, f"{name}.uzf.bud")
     uzobj = flopy.utils.CellBudgetFile(uzpth, precision="double")
     uzobj.get_unique_record_names()
     # '    FLOW-JA-FACE'
@@ -296,25 +288,25 @@ def eval_model(sim):
 
     # convert ndarray to grid dimensions
     tot_stp = 0
-    tinfo = sim.tdis.perioddata.get_data()
+    tinfo = test.tdis.perioddata.get_data()
     for itm in tinfo:
         tot_stp += int(itm[1])
 
     gwet_arr = np.zeros(
         (
             tot_stp,
-            sim.uzf_3lay.dis.nlay.get_data(),
-            sim.uzf_3lay.dis.nrow.get_data(),
-            sim.uzf_3lay.dis.ncol.get_data(),
+            test.model.dis.nlay.get_data(),
+            test.model.dis.nrow.get_data(),
+            test.model.dis.ncol.get_data(),
         )
     )
 
     uzet_arr = np.zeros(
         (
             tot_stp,
-            sim.uzf_3lay.dis.nlay.get_data(),
-            sim.uzf_3lay.dis.nrow.get_data(),
-            sim.uzf_3lay.dis.ncol.get_data(),
+            test.model.dis.nlay.get_data(),
+            test.model.dis.nrow.get_data(),
+            test.model.dis.ncol.get_data(),
         )
     )
 
@@ -336,7 +328,7 @@ def eval_model(sim):
 
             uzet_arr[tm, lay, row, col] = itm[2]
 
-    uzf_strsPerDat = sim.uzf_3lay.uzf.perioddata.get_data()
+    uzf_strsPerDat = test.model.uzf.perioddata.get_data()
     pet = 0
     for tm in range(tot_stp):
         nstps = 0
@@ -345,8 +337,8 @@ def eval_model(sim):
             if tm < nstps:
                 break
 
-        for i in range(sim.uzf_3lay.dis.nrow.get_data()):
-            for j in range(sim.uzf_3lay.dis.ncol.get_data()):
+        for i in range(test.model.dis.nrow.get_data()):
+            for j in range(test.model.dis.ncol.get_data()):
                 if (0, i, j) in cell_iuz_dict:
                     iuz = cell_iuz_dict[
                         (0, i, j)
@@ -367,17 +359,14 @@ def eval_model(sim):
                         + str(j + 1)
                     )
 
-    print("Finished running checks")
-
 
-@pytest.mark.parametrize("name", ex)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx,name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_uzf_surfdep.py b/autotest/test_gwf_uzf_surfdep.py
index 824727a9fff..68a8f3d3285 100644
--- a/autotest/test_gwf_uzf_surfdep.py
+++ b/autotest/test_gwf_uzf_surfdep.py
@@ -7,7 +7,6 @@
 
 
 def build_model(dir, exe):
-
     nlay, nrow, ncol = 3, 1, 10
     nper = 1
     perlen = [20.0]
@@ -98,7 +97,7 @@ def build_model(dir, exe):
     )
 
     # transient uzf info
-    # iuzno  cellid landflg ivertcn surfdp vks thtr thts thti eps [bndnm]
+    # ifno  cellid landflg ivertcn surfdp vks thtr thts thti eps [bndnm]
     uzf_pkdat = [
         [0, (0, 0, 1), 1, 8, 6, 1, 0.05, 0.35, 0.05, 4, "uzf01"],
         [1, (0, 0, 2), 1, 9, 6, 1, 0.05, 0.35, 0.05, 4, "uzf02"],
@@ -187,7 +186,7 @@ def build_model(dir, exe):
 
 def test_mf6model(function_tmpdir, targets):
     # build and run the test model
-    mf6 = targets.mf6
+    mf6 = targets["mf6"]
     sim = build_model(str(function_tmpdir), mf6)
     sim.write_simulation()
     sim.run_simulation()
@@ -196,10 +195,8 @@ def test_mf6model(function_tmpdir, targets):
     f = open(str(function_tmpdir / "mfsim.lst"), "r")
     lines = f.readlines()
     error_count = 0
-    expected_msg = False
     for line in lines:
         if "SURFDEP" and "cannot" in line:
-            expected_msg = True
             error_count += 1
 
     assert error_count == 8, (
diff --git a/autotest/test_gwf_uzf_wc_output.py b/autotest/test_gwf_uzf_wc_output.py
index bd43193ace4..b27d978674c 100644
--- a/autotest/test_gwf_uzf_wc_output.py
+++ b/autotest/test_gwf_uzf_wc_output.py
@@ -4,12 +4,12 @@
 import flopy.utils.binaryfile as bf
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
 include_NWT = False
 
-ex = ["uzf_3lay_wc_chk"]
+cases = ["uzf_3lay_wc_chk"]
 
 iuz_cell_dict = {}
 cell_iuz_dict = {}
@@ -49,7 +49,7 @@
     3: [[(2, 0, 0), ghbelv2, ghbcond], [(2, 0, ncol - 1), ghbelv2, ghbcond]],
 }
 
-# iuzno  cellid landflg ivertcn surfdp vks thtr thts thti eps [bndnm]
+# ifno  cellid landflg ivertcn surfdp vks thtr thts thti eps [bndnm]
 surfdep1 = 1.0
 surfdep2 = 0.001
 vks = 0.5
@@ -223,12 +223,11 @@
 
 
 def build_mf6_model(idx, ws):
-
     tdis_rc = []
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
     sim = flopy.mf6.MFSimulation(
@@ -343,8 +342,7 @@ def build_mf6_model(idx, ws):
 
 
 def build_mfnwt_model(idx, ws):
-
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW-NWT files
     ws = os.path.join(ws, "mfnwt")
@@ -435,25 +433,22 @@ def build_mfnwt_model(idx, ws):
     return mf
 
 
-def build_model(idx, ws):
+def build_models(idx, test):
     # Start by building the MF6 model
-    sim = build_mf6_model(idx, ws)
+    sim = build_mf6_model(idx, test.workspace)
 
     # Construct MF-NWT model for comparing water contents
     #   Commented out to avoid NWT dependency, but left behind for
     #   local testing if needed in the future.
     if include_NWT:
-        mc = build_mfnwt_model(idx, ws)
+        mc = build_mfnwt_model(idx, test.workspace)
     else:
         mc = None
     return sim, mc
 
 
-def eval_model(sim):
-    print("evaluating model...")
-
-    name = sim.name
-    ws = sim.simpath
+def check_output(idx, test):
+    ws = test.workspace
 
     # Get the MF6 heads
     fpth = os.path.join(ws, "uzf_3lay_wc_chk.hds")
@@ -461,7 +456,7 @@ def eval_model(sim):
     hds = hobj.get_alldata()
 
     # Get the MF6 water contents
-    wcpth = os.path.join(ws, ex[0] + ".uzfwc.bin")
+    wcpth = os.path.join(ws, cases[0] + ".uzfwc.bin")
     mf6_wc_obj = bf.HeadFile(wcpth, text="   water-content")
 
     ckstpkper_wc = mf6_wc_obj.get_kstpkper()
@@ -541,20 +536,13 @@ def eval_model(sim):
     print("Finished running checks")
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=eval_model,
-            idxsim=0,
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_vsc01.py b/autotest/test_gwf_vsc01.py
index 5b27cebda76..4abc3c1bf80 100644
--- a/autotest/test_gwf_vsc01.py
+++ b/autotest/test_gwf_vsc01.py
@@ -1,10 +1,9 @@
-# ## Test problem for VSC
-#
-# Uses constant head and general-head boundaries on the left and right
-# sides of the model domain, respectively, to drive flow from left to
-# right.  Tests that head-dependent boundary conditions are properly
-# accounting for viscosity when VSC is active.
-#
+"""
+Uses constant head and general-head boundaries on the left and right
+sides of the model domain, respectively, to drive flow from left to
+right.  Tests that head-dependent boundary conditions are properly
+accounting for viscosity when VSC is active.
+"""
 
 # Imports
 
@@ -14,11 +13,11 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
+cases = ["no-vsc01-bnd", "vsc01-bnd", "no-vsc01-k"]
 hyd_cond = [1205.49396942506, 864.0]  # Hydraulic conductivity (m/d)
-ex = ["no-vsc01-bnd", "vsc01-bnd", "no-vsc01-k"]
 viscosity_on = [False, True, False]
 hydraulic_conductivity = [hyd_cond[0], hyd_cond[1], hyd_cond[1]]
 
@@ -57,15 +56,11 @@
 nouter, ninner = 100, 300
 hclose, rclose, relax = 1e-10, 1e-6, 0.97
 
-#
-# MODFLOW 6 flopy GWF simulation object (sim) is returned
-#
-
 
-def build_model(idx, dir):
+def build_models(idx, test):
     # Base simulation and model name and workspace
-    ws = dir
-    name = ex[idx]
+    ws = test.workspace
+    name = cases[idx]
 
     print("Building model...{}".format(name))
 
@@ -253,15 +248,13 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # read flow results from model
-    name = ex[sim.idxsim]
+    name = cases[idx]
     gwfname = "gwf-" + name
 
     fname = gwfname + ".bud"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     budobj = flopy.utils.CellBudgetFile(fname, precision="double")
     outbud = budobj.get_data(text="             GHB")
@@ -269,14 +262,14 @@ def eval_results(sim):
     # Establish known answer:
     stored_ans = -151.63446156218242
 
-    if sim.idxsim == 0:
+    if idx == 0:
         no_vsc_bud_last = np.array(outbud[-1].tolist())
         sim_val_1 = no_vsc_bud_last[:, 2].sum()
 
         # Ensure latest simulated value hasn't changed from stored answer
         assert np.allclose(
             sim_val_1, stored_ans, atol=1e-4
-        ), "Flow in the " + ex[
+        ), "Flow in the " + cases[
             0
         ] + " test problem (doesn't simulate " "viscosity) has changed,\n should be " + str(
             stored_ans
@@ -284,14 +277,14 @@ def eval_results(sim):
             sim_val_1
         )
 
-    elif sim.idxsim == 1:
+    elif idx == 1:
         with_vsc_bud_last = np.array(outbud[-1].tolist())
         sim_val_2 = with_vsc_bud_last[:, 2].sum()
 
         # Ensure latest simulated value hasn't changed from stored answer
         assert np.allclose(
             sim_val_2, stored_ans, atol=1e-4
-        ), "Flow in the " + ex[
+        ), "Flow in the " + cases[
             1
         ] + " test problem (simulates " "viscosity) has changed,\n should be " + str(
             stored_ans
@@ -299,32 +292,41 @@ def eval_results(sim):
             sim_val_2
         )
 
-    elif sim.idxsim == 2:
+    elif idx == 2:
         no_vsc_low_k_bud_last = np.array(outbud[-1].tolist())
         sim_val_3 = no_vsc_low_k_bud_last[:, 2].sum()
 
         # Ensure the flow leaving model 3 is less than what leaves model 2
         assert abs(stored_ans) > abs(sim_val_3), (
             "Exit flow from model "
-            + ex[1]
+            + cases[1]
             + " should be greater than flow exiting "
-            + ex[2]
+            + cases[2]
             + ", but it is not."
         )
 
+    # Ensure that binary output file is readable (has the correct header)
+    vsc_filerecord = "{}.vsc.bin".format(gwfname)
+    fname = os.path.join(test.workspace, vsc_filerecord)
+    if os.path.isfile(fname):
+        vscobj = flopy.utils.HeadFile(
+            fname, precision="double", text="VISCOSITY"
+        )
+        try:
+            data = vscobj.get_alldata()
+            print(data.shape)
+            data.shape == (500, 1, 10, 80)
+        except:
+            print("Binary viscosity output file was not read successfully")
+
 
-# - No need to change any code below
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_vsc02.py b/autotest/test_gwf_vsc02.py
index a3fb061646e..3598a10cb4a 100644
--- a/autotest/test_gwf_vsc02.py
+++ b/autotest/test_gwf_vsc02.py
@@ -1,11 +1,10 @@
-# ## Test problem for VSC
-#
-# Uses general-head and drain boundaries on the left and right
-# sides of the model domain, respectively, to drive flow from left to
-# right.  Tests that head-dependent boundary conditions are properly
-# accounting for viscosity when VSC is active.  Similar to gwf-vsc01-bnd
-# but employs head-dependent boundary on the left and right side of the
-# model
+"""Uses general-head and drain boundaries on the left and right
+sides of the model domain, respectively, to drive flow from left to
+right.  Tests that head-dependent boundary conditions are properly
+accounting for viscosity when VSC is active.  Similar to gwf-vsc01-bnd
+but employs head-dependent boundary on the left and right side of the
+model
+"""
 
 # Imports
 
@@ -15,12 +14,12 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
 # Setup scenario input
+cases = ["no-vsc02-bnd", "vsc02-bnd", "no-vsc02-k"]
 hyd_cond = [1205.49396942506, 864.0]  # Hydraulic conductivity (m/d)
-ex = ["no-vsc02-bnd", "vsc02-bnd", "no-vsc02-k"]
 viscosity_on = [False, True, False]
 hydraulic_conductivity = [hyd_cond[0], hyd_cond[1], hyd_cond[1]]
 
@@ -59,15 +58,11 @@
 nouter, ninner = 100, 300
 hclose, rclose, relax = 1e-10, 1e-6, 0.97
 
-#
-# MODFLOW 6 flopy GWF simulation object (sim) is returned
-#
-
 
-def build_model(idx, dir):
+def build_models(idx, test):
     # Base simulation and model name and workspace
-    ws = dir
-    name = ex[idx]
+    ws = test.workspace
+    name = cases[idx]
 
     print("Building model...{}".format(name))
 
@@ -256,15 +251,13 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # read flow results from model
-    name = ex[sim.idxsim]
+    name = cases[idx]
     gwfname = "gwf-" + name
 
     fname = gwfname + ".bud"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     budobj = flopy.utils.CellBudgetFile(fname, precision="double")
     outbud = budobj.get_data(text="             GHB")
@@ -272,14 +265,14 @@ def eval_results(sim):
     # Establish known answer:
     stored_ans = 452.5316256451224
 
-    if sim.idxsim == 0:
+    if idx == 0:
         no_vsc_bud_last = np.array(outbud[-1].tolist())
         sim_val_1 = no_vsc_bud_last[:, 2].sum()
 
         # Ensure latest simulated value hasn't changed from stored answer
         assert np.allclose(
             sim_val_1, stored_ans, atol=1e-4
-        ), "Flow in the " + ex[
+        ), "Flow in the " + cases[
             0
         ] + " test problem (doesn't simulate " "viscosity) has changed,\n should be " + str(
             stored_ans
@@ -287,14 +280,14 @@ def eval_results(sim):
             sim_val_1
         )
 
-    elif sim.idxsim == 1:
+    elif idx == 1:
         with_vsc_bud_last = np.array(outbud[-1].tolist())
         sim_val_2 = with_vsc_bud_last[:, 2].sum()
 
         # Ensure latest simulated value hasn't changed from stored answer
         assert np.allclose(
             sim_val_2, stored_ans, atol=1e-4
-        ), "Flow in the " + ex[
+        ), "Flow in the " + cases[
             1
         ] + " test problem (simulates " "viscosity) has changed,\n should be " + str(
             stored_ans
@@ -302,31 +295,27 @@ def eval_results(sim):
             sim_val_2
         )
 
-    elif sim.idxsim == 2:
+    elif idx == 2:
         no_vsc_low_k_bud_last = np.array(outbud[-1].tolist())
         sim_val_3 = no_vsc_low_k_bud_last[:, 2].sum()
 
         # Ensure the flow leaving model 3 is less than what leaves model 2
         assert abs(stored_ans) > abs(sim_val_3), (
             "Exit flow from model "
-            + ex[1]
+            + cases[1]
             + " should be greater than flow existing "
-            + ex[2]
+            + cases[2]
             + ", but it is not."
         )
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_vsc03_sfr.py b/autotest/test_gwf_vsc03_sfr.py
index 97e0148e148..44a1b7bebe7 100644
--- a/autotest/test_gwf_vsc03_sfr.py
+++ b/autotest/test_gwf_vsc03_sfr.py
@@ -1,26 +1,26 @@
-# Scenario envisioned by this test is a river running through a V-shaped
-# valley that loses water to the aquifer at the upper end until it goes
-# dry, then begins to gain flow again in the lower reaches.  River water
-# enters the simulation at 8 deg C.  Aquifer water starts out at 35 deg C.
-# Reference viscosity temperature is 20 deg C.  With the VSC package active,
-# the simulation should predict less loss of river water to the aquifer
-# and more discharge of gw to the stream, compared to the same simulation
-# with the VSC package inactive.
-
-# Imports
+"""
+Scenario envisioned by this test is a river running through a V-shaped
+valley that loses water to the aquifer at the upper end until it goes
+dry, then begins to gain flow again in the lower reaches.  River water
+enters the simulation at 8 deg C.  Aquifer water starts out at 35 deg C.
+Reference viscosity temperature is 20 deg C.  With the VSC package active,
+the simulation should predict less loss of river water to the aquifer
+and more discharge of gw to the stream, compared to the same simulation
+with the VSC package inactive.
+"""
 
 import os
-import sys
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["no-vsc-sfr01", "vsc-sfr01"]
+cases = ["no-vsc-sfr01", "vsc-sfr01"]
 viscosity_on = [False, True]
 
+
 # Equation for determining land surface elevation with a stream running down the middle
 def topElev_sfrCentered(x, y):
     return ((-0.003 * x) + 260.0) + (
@@ -85,17 +85,11 @@ def topElev_sfrCentered(x, y):
 rhob = (1 - porosity) * rho_solids  # Bulk density ($kg/m^3$)
 K_d = C_s / (rho_water * C_p_w)  # Partitioning coefficient ($m^3/kg$)
 
-#
-# MODFLOW 6 flopy GWF & GWT simulation object (sim) is returned
-#
-
 
-def build_model(idx, dir):
+def build_models(idx, test):
     # Base simulation and model name and workspace
-    ws = dir
-    name = ex[idx]
-
-    print("Building model...{}".format(name))
+    ws = test.workspace
+    name = cases[idx]
 
     # generate names for each model
     gwfname = "gwf-" + name
@@ -315,7 +309,8 @@ def build_model(idx, dir):
         print_flows=True,
         print_input=False,
         auxiliary=["VDUMMY", "TEMPERATURE"],
-        unit_conversion=1.486 * 86400,
+        length_conversion=3.28084,
+        time_conversion=86400.0,
         budget_filerecord=budpth,
         mover=False,
         nreaches=nreaches,
@@ -434,15 +429,13 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # read flow results from model
-    name = ex[sim.idxsim]
+    name = cases[idx]
     gwfname = "gwf-" + name
 
     fname = gwfname + ".sfr.cbc"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     budobj = flopy.utils.CellBudgetFile(fname, precision="double")
     outbud = budobj.get_data(text="             GWF")
@@ -478,7 +471,7 @@ def eval_results(sim):
         ]
     )
 
-    if sim.idxsim == 0:
+    if idx == 0:
         # convert np.array to list
         no_vsc_bud_last = np.array(outbud[-1].tolist())
 
@@ -507,7 +500,7 @@ def eval_results(sim):
                 " problem."
             )
 
-    elif sim.idxsim == 1:
+    elif idx == 1:
         with_vsc_bud_last = np.array(outbud[-1].tolist())
 
         # sum up total losses and total gains in the first 10 reaches
@@ -530,17 +523,13 @@ def eval_results(sim):
             )
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_vsc04_lak.py b/autotest/test_gwf_vsc04_lak.py
index 912b2772f5e..af738585aee 100644
--- a/autotest/test_gwf_vsc04_lak.py
+++ b/autotest/test_gwf_vsc04_lak.py
@@ -1,27 +1,28 @@
-# Simple single lake model.  Lake cut into top two layers of a 5 layer
-# model.  Model is loosely based on the first example problem in
-# Merritt and Konikow (2000) which also is one of the MT3D-USGS test
-# problems.  This test developed to isolate lake-aquifer interaction;
-# no SFR or other advanced packages.  Problem set up to have groundwater
-# pass through the lake: gw inflow on the left side, gw outflow on the
-# right side of the lake.  Uses constant stage boundary in the lake to
-# ensure desired flow conditions for testing budget changes with and
-# without VSC active.
-#
-# starting groundwater temperature: 30.0
-# left chd boundary inflow temperature: 30.0
-# starting lake temperature: 4.0
-#
+"""
+Simple single lake model.  Lake cut into top two layers of a 5 layer
+model.  Model is loosely based on the first example problem in
+Merritt and Konikow (2000) which also is one of the MT3D-USGS test
+problems.  This test developed to isolate lake-aquifer interaction;
+no SFR or other advanced packages.  Problem set up to have groundwater
+pass through the lake: gw inflow on the left side, gw outflow on the
+right side of the lake.  Uses constant stage boundary in the lake to
+ensure desired flow conditions for testing budget changes with and
+without VSC active.
+
+starting groundwater temperature: 30.0
+left chd boundary inflow temperature: 30.0
+starting lake temperature: 4.0
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["no-vsc04-lak", "vsc04-lak"]
+cases = ["no-vsc04-lak", "vsc04-lak"]
 viscosity_on = [False, True]
 
 # Model units
@@ -157,16 +158,12 @@
 # Viscosity related parameters
 tviscref = 20.0
 
-#
-# MODFLOW 6 flopy GWF & GWT simulation object (sim) is returned
-#
-
 
-def build_model(idx, ws):
+def build_models(idx, test):
     global lak_lkup_dict
 
     # Base simulation and model name and workspace
-    name = ex[idx]
+    name = cases[idx]
 
     print("Building model...{}".format(name))
 
@@ -175,7 +172,7 @@ def build_model(idx, ws):
     gwtname = "gwt-" + name
 
     sim = flopy.mf6.MFSimulation(
-        sim_name=name, sim_ws=ws, exe_name="mf6", version="mf6"
+        sim_name=name, sim_ws=test.workspace, exe_name="mf6", version="mf6"
     )
 
     tdis_rc = []
@@ -331,7 +328,7 @@ def build_model(idx, ws):
                             # by setting belev==telev, MF6 will automatically
                             # re-assign elevations based on cell dimensions
                             h = [
-                                ilak,  # <lakeno>
+                                ilak,  # <ifno>
                                 ilakconn,  # <iconn>
                                 (k, i - 1, j),  # <cellid(ncelldim)>
                                 "horizontal",  # <claktype>
@@ -614,15 +611,13 @@ def build_model(idx, ws):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # read flow results from model
-    name = ex[sim.idxsim]
+    name = cases[idx]
     gwfname = "gwf-" + name
 
     fname = gwfname + ".lak.bud"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     budobj = flopy.utils.CellBudgetFile(fname, precision="double")
     outbud = budobj.get_data(text="             GWF")
@@ -699,24 +694,24 @@ def eval_results(sim):
     left_chk_with_vsc = []
     right_chk_with_vsc = []
 
-    if sim.idxsim == 0:
+    if idx == 0:
         no_vsc_bud_last = np.array(outbud[-1].tolist())
         no_vsc_bud_np = np.array(no_vsc_bud_last.tolist())
 
-        for idx in np.arange(stored_ans.shape[0]):
-            k, i, j = lak_lkup_dict[idx]
+        for ii in np.arange(stored_ans.shape[0]):
+            k, i, j = lak_lkup_dict[ii]
 
             # left side of lake
             if j < 7:
-                if no_vsc_bud_np[idx, 2] > 0 and stored_ans[idx, 2] > 0:
-                    left_chk_no_vsc.append(no_vsc_bud_np[idx, 2])
-                    left_chk_ans.append(stored_ans[idx, 2])
+                if no_vsc_bud_np[ii, 2] > 0 and stored_ans[ii, 2] > 0:
+                    left_chk_no_vsc.append(no_vsc_bud_np[ii, 2])
+                    left_chk_ans.append(stored_ans[ii, 2])
 
             # right side of lake
             if j > 9:
-                if no_vsc_bud_np[idx, 2] < 0 and stored_ans[idx, 2] < 0:
-                    right_chk_no_vsc.append(no_vsc_bud_np[idx, 2])
-                    right_chk_ans.append(stored_ans[idx, 2])
+                if no_vsc_bud_np[ii, 2] < 0 and stored_ans[ii, 2] < 0:
+                    right_chk_no_vsc.append(no_vsc_bud_np[ii, 2])
+                    right_chk_ans.append(stored_ans[ii, 2])
 
         # Check that all the flows entering the lak in the 'with vsc' model are greater
         # than their 'no vsc' counterpart
@@ -737,24 +732,24 @@ def eval_results(sim):
             "solution."
         )
 
-    elif sim.idxsim == 1:
+    elif idx == 1:
         with_vsc_bud_last = np.array(outbud[-1].tolist())
         with_vsc_bud_np = np.array(with_vsc_bud_last.tolist())
 
-        for idx in np.arange(stored_ans.shape[0]):
-            k, i, j = lak_lkup_dict[idx]
+        for ii in np.arange(stored_ans.shape[0]):
+            k, i, j = lak_lkup_dict[ii]
 
             # left side of lake
             if j < 7:
-                if stored_ans[idx, 2] > 0 and with_vsc_bud_np[idx, 2] > 0:
-                    left_chk_no_vsc.append(stored_ans[idx, 2])
-                    left_chk_with_vsc.append(with_vsc_bud_np[idx, 2])
+                if stored_ans[ii, 2] > 0 and with_vsc_bud_np[ii, 2] > 0:
+                    left_chk_no_vsc.append(stored_ans[ii, 2])
+                    left_chk_with_vsc.append(with_vsc_bud_np[ii, 2])
 
             # right side of lake
             if j > 9:
-                if stored_ans[idx, 2] < 0 and with_vsc_bud_np[idx, 2] < 0:
-                    right_chk_no_vsc.append(stored_ans[idx, 2])
-                    right_chk_with_vsc.append(with_vsc_bud_np[idx, 2])
+                if stored_ans[ii, 2] < 0 and with_vsc_bud_np[ii, 2] < 0:
+                    right_chk_no_vsc.append(stored_ans[ii, 2])
+                    right_chk_with_vsc.append(with_vsc_bud_np[ii, 2])
 
         # Check that all the flows entering the lak in the 'with vsc' model are greater
         # than their 'no vsc' counterpart
@@ -774,17 +769,13 @@ def eval_results(sim):
         )
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_vsc05_hfb.py b/autotest/test_gwf_vsc05_hfb.py
index 490139b73e6..16d62c121a9 100644
--- a/autotest/test_gwf_vsc05_hfb.py
+++ b/autotest/test_gwf_vsc05_hfb.py
@@ -1,36 +1,32 @@
-# ## Test problem for VSC and HFB
-#
-# Uses constant head and general-head boundaries on the left and right
-# sides of a 10 row by 10 column by 1 layer model to drive flow from left to
-# right.  Tests that a horizontal flow barrier accounts for changes in
-# viscosity when temperature is simulated. Barrier is between middle two
-# columns, but only cuts across the bottom 5 rows.
-# Model 1: VSC inactive, uses a higher speified K that matches what the VSC
-#          package will come up with
-# Model 2: VSC active, uses a lower K so that when VSC is applied, resulting
-#          K's match model 1 and should result in the same flows across the
-#          model domain
-# Model 3: VSC inactive, uses the lower K of model 2 and checks that flows
-#          in model 3 are indeed lower than in model 2 when turning VSC off.
-#          Model simulates hot groundwater with lower viscosity resulting in
-#          more gw flow through the model domain.Flows that are checked are
-#          the row-wise flows between columns 5 and 6 (e.g., cell 5 to 6, 15
-#          to 16, etc.)
-#
-
-# Imports
+"""
+Uses constant head and general-head boundaries on the left and right
+sides of a 10 row by 10 column by 1 layer model to drive flow from left to
+right.  Tests that a horizontal flow barrier accounts for changes in
+viscosity when temperature is simulated. Barrier is between middle two
+columns, but only cuts across the bottom 5 rows.
+Model 1: VSC inactive, uses a higher speified K that matches what the VSC
+         package will come up with
+Model 2: VSC active, uses a lower K so that when VSC is applied, resulting
+         K's match model 1 and should result in the same flows across the
+         model domain
+Model 3: VSC inactive, uses the lower K of model 2 and checks that flows
+         in model 3 are indeed lower than in model 2 when turning VSC off.
+         Model simulates hot groundwater with lower viscosity resulting in
+         more gw flow through the model domain.Flows that are checked are
+         the row-wise flows between columns 5 and 6 (e.g., cell 5 to 6, 15
+         to 16, etc.)
+"""
 
 import os
-import sys
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
+cases = ["no-vsc05-hfb", "vsc05-hfb", "no-vsc05-k"]
 hyd_cond = [1205.49396942506, 864.0]  # Hydraulic conductivity (m/d)
-ex = ["no-vsc05-hfb", "vsc05-hfb", "no-vsc05-k"]
 viscosity_on = [False, True, False]
 hydraulic_conductivity = [hyd_cond[0], hyd_cond[1], hyd_cond[1]]
 
@@ -68,15 +64,11 @@
 nouter, ninner = 100, 300
 hclose, rclose, relax = 1e-10, 1e-6, 0.97
 
-#
-# MODFLOW 6 flopy GWF simulation object (sim) is returned
-#
-
 
-def build_model(idx, dir):
+def build_models(idx, test):
     # Base simulation and model name and workspace
-    ws = dir
-    name = ex[idx]
+    ws = test.workspace
+    name = cases[idx]
 
     print("Building model...{}".format(name))
 
@@ -282,22 +274,22 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # read flow results from model
-    name = ex[sim.idxsim]
+    name = cases[idx]
     gwfname = "gwf-" + name
-    sim1 = flopy.mf6.MFSimulation.load(sim_ws=sim.simpath, load_only=["dis"])
+    sim1 = flopy.mf6.MFSimulation.load(
+        sim_ws=test.workspace, load_only=["dis"]
+    )
     gwf = sim1.get_model(gwfname)
 
     # Get grid data
     grdname = gwfname + ".dis.grb"
-    bgf = flopy.mf6.utils.MfGrdFile(os.path.join(sim.simpath, grdname))
+    bgf = flopy.mf6.utils.MfGrdFile(os.path.join(test.workspace, grdname))
     ia, ja = bgf.ia, bgf.ja
 
     fname = gwfname + ".bud"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     budobj = flopy.utils.CellBudgetFile(fname, precision="double")
     outbud = budobj.get_data(text="    FLOW-JA-FACE")[-1].squeeze()
@@ -330,7 +322,7 @@ def eval_results(sim):
             if cellm == celln - 1:
                 vals_to_store.append([cellm, celln, outbud[ipos]])
 
-    if sim.idxsim == 0:
+    if idx == 0:
         no_vsc_bud_last = np.array(vals_to_store)
 
         # Ensure with and without VSC simulations give nearly identical flow results
@@ -339,24 +331,24 @@ def eval_results(sim):
             no_vsc_bud_last[:, 2], stored_ans[:, 2], atol=1e-3
         ), (
             "Flow in models "
-            + ex[0]
+            + cases[0]
             + " and the established answer should be approximately "
             "equal, but are not."
         )
 
-    elif sim.idxsim == 1:
+    elif idx == 1:
         with_vsc_bud_last = np.array(vals_to_store)
 
         assert np.allclose(
             with_vsc_bud_last[:, 2], stored_ans[:, 2], atol=1e-3
         ), (
             "Flow in models "
-            + ex[1]
+            + cases[1]
             + " and the established answer should be approximately "
             "equal, but are not."
         )
 
-    elif sim.idxsim == 2:
+    elif idx == 2:
         no_vsc_low_k_bud_last = np.array(vals_to_store)
 
         # Ensure the cell-to-cell flow between columns 5 and 6 in model
@@ -364,23 +356,19 @@ def eval_results(sim):
         assert np.less(no_vsc_low_k_bud_last[:, 2], stored_ans[:, 2]).all(), (
             "Exit flow from model the established answer "
             "should be greater than flow existing "
-            + ex[2]
+            + cases[2]
             + ", but it is not."
         )
 
 
 # - No need to change any code below
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        targets=targets,
     )
+    test.run()
diff --git a/autotest/test_gwf_wel01.py b/autotest/test_gwf_wel01.py
index 6217184b4de..f1984e99300 100644
--- a/autotest/test_gwf_wel01.py
+++ b/autotest/test_gwf_wel01.py
@@ -8,10 +8,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["wel01"]
+cases = ["wel01"]
 
 # set static data
 nper = 1
@@ -31,15 +31,15 @@
 hclose, rclose, relax = 1e-9, 1e-6, 1.0
 
 
-def build_model(idx, ws):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
 
     # build MODFLOW 6 files
     sim = flopy.mf6.MFSimulation(
         sim_name=name,
         version="mf6",
         exe_name="mf6",
-        sim_ws=ws,
+        sim_ws=test.workspace,
     )
     # create tdis package
     tdis = flopy.mf6.ModflowTdis(
@@ -142,16 +142,14 @@ def build_model(idx, ws):
     return sim, None
 
 
-def eval_obs(sim):
-    print("evaluating well observations...")
-
+def check_output(idx, test):
     # MODFLOW 6 observations
     dtol = 1e-9
     for file_name in (
         "wel.obs.csv",
         "wel.obs.dup.csv",
     ):
-        fpth = os.path.join(sim.simpath, file_name)
+        fpth = os.path.join(test.workspace, file_name)
         try:
             tc = np.genfromtxt(fpth, names=True, delimiter=",")
         except:
@@ -165,15 +163,15 @@ def eval_obs(sim):
         msg = f"maximum absolute well rates ({diffmax}) "
 
         if diffmax > dtol:
-            sim.success = False
+            test.success = False
             msg += f"exceeds {dtol}"
             assert diffmax < dtol, msg
         else:
-            sim.success = True
+            test.success = True
             print("    " + msg)
 
     # MODFLOW 6 AFR CSV output file
-    fpth = os.path.join(sim.simpath, "wel01.afr.csv")
+    fpth = os.path.join(test.workspace, "wel01.afr.csv")
     try:
         afroutput = np.genfromtxt(
             fpth, names=True, delimiter=",", deletechars=""
@@ -188,17 +186,13 @@ def eval_obs(sim):
     assert np.allclose(a1, a2), errmsg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_obs, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwf_zb01.py b/autotest/test_gwf_zb01.py
index dd29209ac9c..33b67b5732b 100644
--- a/autotest/test_gwf_zb01.py
+++ b/autotest/test_gwf_zb01.py
@@ -1,14 +1,13 @@
 import os
-from pathlib import Path
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["zbud6_zb01"]
-htol = [None for idx in range(len(ex))]
+cases = ["zbud6_zb01"]
+htol = [None for _ in range(len(cases))]
 dtol = 1e-3
 budtol = 1e-2
 bud_lst = [
@@ -31,14 +30,14 @@
 # static model data
 # temporal discretization
 nper = 31
-perlen = [1.0] + [365.2500000 for i in range(nper - 1)]
-nstp = [1] + [6 for i in range(nper - 1)]
-tsmult = [1.0] + [1.3 for i in range(nper - 1)]
-# tsmult = [1.0] + [1.0 for i in range(nper - 1)]
-steady = [True] + [False for i in range(nper - 1)]
+perlen = [1.0] + [365.2500000 for _ in range(nper - 1)]
+nstp = [1] + [6 for _ in range(nper - 1)]
+tsmult = [1.0] + [1.3 for _ in range(nper - 1)]
+# tsmult = [1.0] + [1.0 for _ in range(nper - 1)]
+steady = [True] + [False for _ in range(nper - 1)]
 tdis_rc = []
-for idx in range(nper):
-    tdis_rc.append((perlen[idx], nstp[idx], tsmult[idx]))
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
 # spatial discretization data
 nlay, nrow, ncol = 3, 10, 10
@@ -111,13 +110,13 @@
 
 
 # variant SUB package problem 3
-def build_model(idx, dir, exe):
-    name = ex[idx]
+def build_models(idx, test):
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name=exe, sim_ws=ws
+        sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
     # create tdis package
     tdis = flopy.mf6.ModflowTdis(
@@ -217,21 +216,18 @@ def build_model(idx, dir, exe):
     return sim, None
 
 
-def eval_zb6(sim, exe):
-    print("evaluating zonebudget...")
-    simpath = Path(sim.simpath)
-
+def check_output(idx, test):
     # build zonebudget files
     zones = [-1000000, 1000000, 9999999]
     nzones = len(zones)
-    with open(simpath / "zonebudget.nam", "w") as f:
+    with open(test.workspace / "zonebudget.nam", "w") as f:
         f.write("BEGIN ZONEBUDGET\n")
-        f.write(f"  BUD {os.path.basename(sim.name)}.cbc\n")
-        f.write(f"  ZON {os.path.basename(sim.name)}.zon\n")
-        f.write(f"  GRB {os.path.basename(sim.name)}.dis.grb\n")
+        f.write(f"  BUD {os.path.basename(test.name)}.cbc\n")
+        f.write(f"  ZON {os.path.basename(test.name)}.zon\n")
+        f.write(f"  GRB {os.path.basename(test.name)}.dis.grb\n")
         f.write("END ZONEBUDGET\n")
 
-    with open(simpath / f"{os.path.basename(sim.name)}.zon", "w") as f:
+    with open(test.workspace / f"{os.path.basename(test.name)}.zon", "w") as f:
         f.write("BEGIN DIMENSIONS\n")
         f.write(f"  NCELLS {size3d}\n")
         f.write("END DIMENSIONS\n\n")
@@ -243,18 +239,23 @@ def eval_zb6(sim, exe):
 
     # run zonebudget
     success, buff = flopy.run_model(
-        exe,
+        test.targets["zbud6"],
         "zonebudget.nam",
-        model_ws=sim.simpath,
+        model_ws=test.workspace,
         silent=False,
         report=True,
     )
 
     assert success
-    sim.success = success
+    test.success = success
 
     # read data from csv file
-    zbd = np.genfromtxt(simpath / "zonebudget.csv", names=True, delimiter=",", deletechars="")
+    zbd = np.genfromtxt(
+        test.workspace / "zonebudget.csv",
+        names=True,
+        delimiter=",",
+        deletechars="",
+    )
 
     # sum the data for all zones
     nentries = int(zbd.shape[0] / nzones)
@@ -276,7 +277,9 @@ def eval_zb6(sim, exe):
             ion = 0
 
     # get results from listing file
-    budl = flopy.utils.Mf6ListBudget(simpath / f"{os.path.basename(sim.name)}.lst")
+    budl = flopy.utils.Mf6ListBudget(
+        test.workspace / f"{os.path.basename(test.name)}.lst"
+    )
     names = list(bud_lst)
     d0 = budl.get_budget(names=names)[0]
     dtype = d0.dtype
@@ -288,11 +291,12 @@ def eval_zb6(sim, exe):
     for key in bud_lst:
         d[key] = 0.0
     cobj = flopy.utils.CellBudgetFile(
-        simpath / f"{os.path.basename(sim.name)}.cbc",
-        precision="double")
+        test.workspace / f"{os.path.basename(test.name)}.cbc",
+        precision="double",
+    )
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -310,89 +314,84 @@ def eval_zb6(sim, exe):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, key in enumerate(bud_lst):
-        diff[:, idx] = d0[key] - d[key]
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
     diffmax = np.abs(diff).max()
     msg = f"maximum absolute total-budget difference ({diffmax}) "
 
     # write summary
-    with open(simpath / f"{os.path.basename(sim.name)}.bud.cmp.out", "w") as f:
+    with open(
+        test.workspace / f"{os.path.basename(test.name)}.bud.cmp.out", "w"
+    ) as f:
         for i in range(diff.shape[0]):
             if i == 0:
                 line = f"{'TIME':>10s}"
-                for idx, key in enumerate(bud_lst):
+                for key in bud_lst:
                     line += f"{key + '_LST':>25s}"
                     line += f"{key + '_CBC':>25s}"
                     line += f"{key + '_DIF':>25s}"
                 f.write(line + "\n")
             line = f"{d['totim'][i]:10g}"
-            for idx, key in enumerate(bud_lst):
+            for ii, key in enumerate(bud_lst):
                 line += f"{d0[key][i]:25g}"
                 line += f"{d[key][i]:25g}"
-                line += f"{diff[i, idx]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
 
     # compare zone budget to cbc output
     diffzb = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, (key0, key) in enumerate(zip(zone_lst, bud_lst)):
-        diffzb[:, idx] = zbsum[key0] - d[key]
+    for i, (key0, key) in enumerate(zip(zone_lst, bud_lst)):
+        diffzb[:, i] = zbsum[key0] - d[key]
     diffzbmax = np.abs(diffzb).max()
     msg += (
         f"\nmaximum absolute zonebudget-cell by cell difference ({diffzbmax}) "
     )
 
     # write summary
-    with open(simpath / f"{os.path.basename(sim.name)}.zbud.cmp.out", "w") as f:
+    with open(
+        test.workspace / f"{os.path.basename(test.name)}.zbud.cmp.out", "w"
+    ) as f:
         for i in range(diff.shape[0]):
             if i == 0:
                 line = f"{'TIME':>10s}"
-                for idx, key in enumerate(bud_lst):
+                for i, key in enumerate(bud_lst):
                     line += f"{key + '_ZBUD':>25s}"
                     line += f"{key + '_CBC':>25s}"
                     line += f"{key + '_DIF':>25s}"
                 f.write(line + "\n")
             line = f"{d['totim'][i]:10g}"
-            for idx, (key0, key) in enumerate(zip(zone_lst, bud_lst)):
+            for i, (key0, key) in enumerate(zip(zone_lst, bud_lst)):
                 line += f"{zbsum[key0][i]:25g}"
                 line += f"{d[key][i]:25g}"
-                line += f"{diffzb[i, idx]:25g}"
+                line += f"{diffzb[i, i]:25g}"
             f.write(line + "\n")
 
     if diffmax > budtol or diffzbmax > budtol:
-        sim.success = False
+        test.success = False
         msg += f"\n...exceeds {budtol}"
         assert diffmax < budtol and diffzbmax < budtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    mf6 = targets.mf6
-    zb6 = targets.zbud6
-    test = TestFramework()
-    test.build(lambda i, w: build_model(i, w, mf6), idx, ws)
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=lambda s: eval_zb6(s, zb6),
-            htol=htol[idx],
-            idxsim=idx,
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        htol=htol[idx],
     )
+    test.run()
diff --git a/autotest/test_gwfgwf.py b/autotest/test_gwfgwf.py
new file mode 100644
index 00000000000..f29e05d7ce8
--- /dev/null
+++ b/autotest/test_gwfgwf.py
@@ -0,0 +1,218 @@
+"""
+Test a constant head boundary assigned to one model as
+also functioning as a constant head boundary assigned to
+a connected model.  The constant head term for model 1
+should be calculated to include the flow from model 2.
+Also, the flowja budget term for the constant head cell
+should have a correct residual of zero in the diagonal
+position.
+
+   1  1 -1  gwf1
+   -  -  -
+   1  1  1  gwf2
+
+We assert equality on qresidual being less than tolerance and
+also that total constant head flow is correct.
+"""
+
+import os
+import pathlib as pl
+import math
+import flopy
+import numpy as np
+import pytest
+
+from framework import TestFramework
+
+cases = ["gwfgwf01", "gwfgwf01ifmod"]
+ifmod = [False, True]
+
+
+def build_models(idx, test):
+    sim = get_sim(idx, test.workspace)
+    return sim, None
+
+
+def get_sim(idx, dir):
+    name = cases[idx]
+
+    # solver data
+    nouter, ninner = 100, 300
+    hclose, rclose, relax = 1.e-8, 1e-8, 0.97
+
+    sim = flopy.mf6.MFSimulation(
+        sim_name=name, version="mf6", exe_name="mf6", sim_ws=dir
+    )
+
+    tdis = flopy.mf6.ModflowTdis(
+        sim, 
+        time_units="DAYS", 
+        nper=1, 
+        perioddata=[(1.0, 1, 1)],
+    )
+
+    ims = flopy.mf6.ModflowIms(
+        sim,
+        print_option="SUMMARY",
+        outer_dvclose=hclose,
+        outer_maximum=nouter,
+        under_relaxation="DBD",
+        inner_maximum=ninner,
+        inner_dvclose=hclose,
+        rcloserecord=rclose,
+        linear_acceleration="BICGSTAB",
+        relaxation_factor=relax,
+    )
+
+    gwf0 = add_model(sim, "gwf1", top=0., add_chd=True, add_rch=True)
+    gwf1 = add_model(sim, "gwf2", top=-1., add_chd=False, add_rch=False)
+    gwfgwf = add_gwfexchange(sim, idx)
+
+    return sim
+
+
+def add_model(sim, modelname, top, add_chd, add_rch):
+
+    nlay, nrow, ncol = 1, 1, 3
+    botm = top - 1.0
+    gwf = flopy.mf6.ModflowGwf(sim, modelname=modelname, save_flows=True)
+    dis = flopy.mf6.ModflowGwfdis(
+        gwf,
+        nlay=nlay,
+        nrow=nrow,
+        ncol=ncol,
+        delr=1.0,
+        delc=1.0,
+        top=top,
+        botm=botm,
+    )
+    ic = flopy.mf6.ModflowGwfic(gwf, strt=0.)
+    npf = flopy.mf6.ModflowGwfnpf(
+        gwf,
+        save_specific_discharge=True,
+        save_flows=True,
+        icelltype=0,
+        k=1.0,
+    )
+
+    if add_chd:
+        chdlist = [(0, 0, ncol-1, 0.)]
+        chd = flopy.mf6.ModflowGwfchd(gwf, stress_period_data=chdlist)
+
+    if add_rch:
+        rch = flopy.mf6.ModflowGwfrcha(gwf, recharge=0.001)
+
+    oc = flopy.mf6.ModflowGwfoc(
+        gwf,
+        head_filerecord=f"{modelname}.hds",
+        budget_filerecord=f"{modelname}.cbc",
+        budgetcsv_filerecord=f"{modelname}.cbc.csv",
+        headprintrecord=[("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")],
+        printrecord=[("HEAD", "LAST"), ("BUDGET", "LAST")],
+        saverecord=[("HEAD", "LAST"), ("BUDGET", "LAST")],
+    )
+
+    return gwf
+
+
+def add_gwfexchange(sim, idx):
+    ncol = 3
+    delr = 1.
+    delc = 1.
+    dz = 1.
+    angldegx = 0.0
+    cdist = 1.0
+    gwfgwf_data = [
+        [
+            (0, 0, icol),
+            (0, 0, icol),
+            0,
+            dz / 2.0,
+            dz / 2.0,
+            delr * delc,
+            angldegx,
+            cdist,
+        ]
+        for icol in range(ncol)
+    ]
+    gwfgwf = flopy.mf6.ModflowGwfgwf(
+        sim,
+        exgtype="GWF6-GWF6",
+        save_flows=True,
+        print_flows=True,
+        nexg=len(gwfgwf_data),
+        exgmnamea="gwf1",
+        exgmnameb="gwf2",
+        exchangedata=gwfgwf_data,
+        auxiliary=["ANGLDEGX", "CDIST"],
+        dev_interfacemodel_on=ifmod[idx],
+    )
+    return gwfgwf
+
+
+def check_output(idx, test):
+    sim = test.sims[0]
+    check_model(sim, 0)
+    check_model(sim, 1)
+
+
+def check_model(sim, model_number):
+    print (f"Checking model output (gwf{model_number})")
+    gwf = sim.gwf[model_number]
+    sim_ws = pl.Path(sim.sim_path)
+    fpth = sim_ws / f"gwf{model_number + 1}.dis.grb"
+    grb = flopy.mf6.utils.MfGrdFile(fpth)
+    ia = grb.ia
+    
+    bobj = gwf.output.budget()
+    # print(bobj.list_records())
+    budget_records = bobj.get_data(kstpkper=(0, 0))
+    nrecords = len(budget_records)
+    print(f"detected {nrecords} items in budget file.")
+    for idx in range(nrecords):
+        budget_record = bobj.get_data(idx=idx)[0]
+        print(budget_record)
+
+    model_budget = gwf.output.budgetcsv().data
+    pd = model_budget["PERCENT_DIFFERENCE"][0]
+    print("percent difference: ", model_budget["PERCENT_DIFFERENCE"])
+    errmsg = f"Model percent difference is too large (pd)"
+    assert pd < 1.e-6, errmsg
+
+    # check residual budget term in flowja diagonal position
+    fja = bobj.get_data(text="FLOW-JA-FACE")[0].flatten()
+    success = True
+    atol = 1.e-7
+    for ipos in ia[:-1]:
+        print(ipos, fja[ipos])
+        if fja[ipos] > atol:
+            success = False
+    assert success, f"flowja residual larger than tolerance ({atol})"
+
+    # ensure that the constant head outflow is equal to the 
+    # specified recharge
+    if model_number == 0:
+        chdflows = bobj.get_data(text="chd")[0]
+        vchd = -chdflows["q"][0]
+        vexgchd = model_budget["FLOW-JA-FACE-CHD(GWF-GWF_1)_OUT"][0]
+        v = vchd + vexgchd
+        errmsg = (
+            f"Constant head outflow ({v}) is not equal to the "
+            f"specified recharge inflow (0.002)."
+        )
+        assert math.isclose(v, 0.002), errmsg
+
+    return
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+@pytest.mark.developmode
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+    )
+    test.run()
diff --git a/autotest/test_gwfgwf_lgr.py b/autotest/test_gwfgwf_lgr.py
index 2ac991d04e5..6292114b406 100644
--- a/autotest/test_gwfgwf_lgr.py
+++ b/autotest/test_gwfgwf_lgr.py
@@ -28,20 +28,19 @@
 ensure that vertical flows and horizontal flows are added
 correctly to each model flowja diagonal terms.  This diagonal
 term contains the flow residual for the cell.
-
 """
+
 import os
 
 import flopy
 import numpy as np
 import pytest
 from flopy.utils.lgrutil import Lgr
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["gwfgwf_lgr_classic", "gwfgwf_lgr_ifmod"]
+cases = ["gwfgwf_lgr_classic", "gwfgwf_lgr_ifmod"]
 ifmod = [False, True]
-
 parent_name = "parent"
 child_name = "child"
 h_left = 1.0
@@ -52,11 +51,11 @@
 k33 = 1.0
 
 
-def get_model(idx, dir):
+def get_model(idx, test):
     global child_domain
     global hclose
 
-    name = ex[idx]
+    name = cases[idx]
 
     # tdis period data
     nper = 1
@@ -109,7 +108,7 @@ def get_model(idx, dir):
     chd_spd = {0: chd_data}
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name,
         version="mf6",
@@ -238,30 +237,30 @@ def get_model(idx, dir):
     return sim
 
 
-def build_model(idx, exdir):
+def build_models(idx, exdir):
     sim = get_model(idx, exdir)
     return sim, None
 
 
-def eval_heads(sim):
+def check_output(idx, test):
     print("comparing heads  for child model to analytical result...")
 
-    fpth = os.path.join(sim.simpath, f"{child_name}.hds")
+    fpth = os.path.join(test.workspace, f"{child_name}.hds")
     hds_c = flopy.utils.HeadFile(fpth)
     heads_c = hds_c.get_data()
 
-    fpth = os.path.join(sim.simpath, f"{child_name}.dis.grb")
+    fpth = os.path.join(test.workspace, f"{child_name}.dis.grb")
     grb_c = flopy.mf6.utils.MfGrdFile(fpth)
 
     # check flowja residual
     for mname in [parent_name, child_name]:
         print(f"Checking flowja residual for model {mname}")
 
-        fpth = os.path.join(sim.simpath, f"{mname}.dis.grb")
+        fpth = os.path.join(test.workspace, f"{mname}.dis.grb")
         grb = flopy.mf6.utils.MfGrdFile(fpth)
         ia = grb._datadict["IA"] - 1
 
-        fpth = os.path.join(sim.simpath, f"{mname}.cbc")
+        fpth = os.path.join(test.workspace, f"{mname}.cbc")
         assert os.path.isfile(fpth)
         cbb = flopy.utils.CellBudgetFile(fpth, precision="double")
         flow_ja_face = cbb.get_data(idx=0)
@@ -276,18 +275,14 @@ def eval_heads(sim):
             assert np.allclose(res, 0.0, atol=1.0e-6), errmsg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 @pytest.mark.developmode
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_heads, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_adv01.py b/autotest/test_gwt_adv01.py
index 7132f16d38e..62c41a4649d 100644
--- a/autotest/test_gwt_adv01.py
+++ b/autotest/test_gwt_adv01.py
@@ -1,8 +1,6 @@
 """
-MODFLOW 6 Autotest
 Test the advection schemes in the gwt advection package for a one-dimensional
 model grid of square cells.
-
 """
 
 import os
@@ -10,14 +8,14 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["adv01a", "adv01b", "adv01c"]
+cases = ["adv01a", "adv01b", "adv01c"]
 scheme = ["upstream", "central", "tvd"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 100
     nper = 1
     perlen = [5.0]
@@ -42,10 +40,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -241,13 +239,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -585,21 +581,17 @@ def eval_transport(sim):
     creslist = [cres1, cres2, cres3]
 
     assert np.allclose(
-        creslist[sim.idxsim], conc
+        creslist[idx], conc
     ), "simulated concentrations do not match with known solution."
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_adv01_fmi.py b/autotest/test_gwt_adv01_fmi.py
index 84faee0f9a0..d40dd4cf7b1 100644
--- a/autotest/test_gwt_adv01_fmi.py
+++ b/autotest/test_gwt_adv01_fmi.py
@@ -1,8 +1,6 @@
 """
-MODFLOW 6 Autotest
 Test the advection schemes in the gwt advection package for a one-dimensional
 model grid of square cells.
-
 """
 
 import os
@@ -12,14 +10,14 @@
 import pytest
 from flopy.utils.binaryfile import write_budget, write_head
 from flopy.utils.gridutil import uniform_flow_field
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["adv01a_fmi", "adv01b_fmi", "adv01c_fmi"]
+cases = ["adv01a_fmi", "adv01b_fmi", "adv01c_fmi"]
 scheme = ["upstream", "central", "tvd"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 100
     nper = 1
     perlen = [5.0]
@@ -41,10 +39,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -217,13 +215,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -561,21 +557,17 @@ def eval_transport(sim):
     creslist = [cres1, cres2, cres3]
 
     assert np.allclose(
-        creslist[sim.idxsim], conc
+        creslist[idx], conc
     ), "simulated concentrations do not match with known solution."
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_adv01_gwtgwt.py b/autotest/test_gwt_adv01_gwtgwt.py
index 29624b7054a..f003beb121e 100644
--- a/autotest/test_gwt_adv01_gwtgwt.py
+++ b/autotest/test_gwt_adv01_gwtgwt.py
@@ -1,8 +1,6 @@
 """
-MODFLOW 6 Autotest
 Test the advection schemes in the gwt advection package for a one-dimensional
 model grid of square cells.
-
 """
 
 import os
@@ -10,13 +8,17 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["adv01a_gwtgwt", "adv01b_gwtgwt", "adv01c_gwtgwt"]
+cases = ["adv01a_gwtgwt", "adv01b_gwtgwt", "adv01c_gwtgwt"]
 scheme = ["upstream", "central", "tvd"]
 gdelr = 1.0
 
+# solver settings
+nouter, ninner = 100, 300
+hclose, rclose, relax = 1e-6, 1e-6, 1.0
+
 
 def get_gwf_model(sim, gwfname, gwfpath, modelshape, chdspd=None, welspd=None):
     nlay, nrow, ncol, xshift, yshift = modelshape
@@ -33,8 +35,6 @@ def get_gwf_model(sim, gwfname, gwfpath, modelshape, chdspd=None, welspd=None):
         modelname=gwfname,
         save_flows=True,
     )
-    # this doesn't work here
-    # gwf.set_model_relative_path(gwfname)
 
     dis = flopy.mf6.ModflowGwfdis(
         gwf,
@@ -177,8 +177,7 @@ def get_gwt_model(
     return gwt
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     # temporal discretization
     nper = 1
     perlen = [5.0]
@@ -189,7 +188,7 @@ def build_model(idx, dir):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=ws, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -198,10 +197,6 @@ def build_model(idx, dir):
         sim, time_units="DAYS", nper=nper, perioddata=tdis_rc, pname="sim.tdis"
     )
 
-    # solver settings
-    nouter, ninner = 100, 300
-    hclose, rclose, relax = 1e-6, 1e-6, 1.0
-
     # grid information
     nlay, nrow, ncol = 1, 1, 50
 
@@ -335,12 +330,10 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
+def check_output(idx, test):
     gwtname = "transport1"
 
-    fpth = os.path.join(sim.simpath, gwtname, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, gwtname, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -351,7 +344,7 @@ def eval_transport(sim):
 
     gwtname = "transport2"
 
-    fpth = os.path.join(sim.simpath, gwtname, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, gwtname, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -689,12 +682,12 @@ def eval_transport(sim):
     creslist = [cres1, cres2, cres3]
 
     assert np.allclose(
-        creslist[sim.idxsim], conc
+        creslist[idx], conc
     ), "simulated concentrations do not match with known solution."
 
     # check budget
     for mname in ["transport1", "transport2"]:
-        fpth = os.path.join(sim.simpath, mname, f"{mname}.lst")
+        fpth = os.path.join(test.workspace, mname, f"{mname}.lst")
         for line in open(fpth):
             if line.lstrip().startswith("PERCENT"):
                 cumul_balance_error = float(line.split()[3])
@@ -706,13 +699,13 @@ def eval_transport(sim):
 
         # get grid data (from GWF)
         gwfname = "flow1" if mname == "transport1" else "flow2"
-        fpth = os.path.join(sim.simpath, gwfname, f"{gwfname}.dis.grb")
+        fpth = os.path.join(test.workspace, gwfname, f"{gwfname}.dis.grb")
         grb = flopy.mf6.utils.MfGrdFile(fpth)
 
         # Check on residual, which is stored in diagonal position of
         # flow-ja-face.  Residual should be less than convergence tolerance,
         # or this means the residual term is not added correctly.
-        fpth = os.path.join(sim.simpath, mname, f"{mname}.cbc")
+        fpth = os.path.join(test.workspace, mname, f"{mname}.cbc")
         cbb = flopy.utils.CellBudgetFile(fpth)
         flow_ja_face = cbb.get_data(text="FLOW-JA-FACE")
         ia = grb._datadict["IA"] - 1
@@ -726,18 +719,14 @@ def eval_transport(sim):
             # assert np.allclose(res, 0.0, atol=1.0e-6), errmsg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 @pytest.mark.developmode
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_adv02.py b/autotest/test_gwt_adv02.py
index 4d0a5ba635b..1252d353ce9 100644
--- a/autotest/test_gwt_adv02.py
+++ b/autotest/test_gwt_adv02.py
@@ -1,10 +1,8 @@
 """
-MODFLOW 6 Autotest
 Test the advection schemes in the gwt advection package for a one-dimensional
 model grid of triangular cells.  The cells are created by starting with a
 regular grid of squares and then cutting every cell into a triangle, except
 the first and last.
-
 """
 
 import os
@@ -13,10 +11,10 @@
 import flopy.utils.cvfdutil
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["adv02a", "adv02b", "adv02c"]
+cases = ["adv02a", "adv02b", "adv02c"]
 scheme = ["upstream", "central", "tvd"]
 
 
@@ -65,7 +63,7 @@ def cvfd_to_cell2d(verts, iverts):
     return vertices, cell2d
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 100
     nper = 1
     perlen = [5.0]
@@ -87,10 +85,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -300,13 +298,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -938,21 +934,17 @@ def eval_transport(sim):
     creslist = [cres1, cres2, cres3]
 
     assert np.allclose(
-        creslist[sim.idxsim], conc
+        creslist[idx], conc
     ), "simulated concentrations do not match with known solution."
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_adv03.py b/autotest/test_gwt_adv03.py
index 5134fe038f7..562e2567b43 100644
--- a/autotest/test_gwt_adv03.py
+++ b/autotest/test_gwt_adv03.py
@@ -1,10 +1,8 @@
 """
-MODFLOW 6 Autotest
 Test the advection schemes in the gwt advection package for a three-dimensional
 model grid of triangular cells.  The cells are created by starting with a
 regular grid of squares and then cutting every cell into a triangle, except
 the first and last.
-
 """
 
 import os
@@ -13,10 +11,10 @@
 import flopy.utils.cvfdutil
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["adv03a", "adv03b", "adv03c"]
+cases = ["adv03a", "adv03b", "adv03c"]
 scheme = ["upstream", "central", "tvd"]
 
 
@@ -65,7 +63,7 @@ def cvfd_to_cell2d(verts, iverts):
     return vertices, cell2d
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 5, 10, 20
     nper = 1
     delr = 1.0
@@ -93,10 +91,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -331,13 +329,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -482,29 +478,25 @@ def eval_transport(sim):
     # dimensional
     creslist = [cres1, cres2, cres3]
     ncellsperrow = cres1.shape[0]
-    assert np.allclose(creslist[sim.idxsim], conc[0, 0, 0:ncellsperrow]), (
+    assert np.allclose(creslist[idx], conc[0, 0, 0:ncellsperrow]), (
         "simulated concentrations do not match with known solution.",
-        creslist[sim.idxsim],
+        creslist[idx],
         conc[0, 0, -ncellsperrow:],
     )
-    assert np.allclose(creslist[sim.idxsim], conc[0, 0, -ncellsperrow:]), (
+    assert np.allclose(creslist[idx], conc[0, 0, -ncellsperrow:]), (
         "simulated concentrations do not match with known solution.",
-        creslist[sim.idxsim],
+        creslist[idx],
         conc[0, 0, -ncellsperrow:],
     )
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_adv04.py b/autotest/test_gwt_adv04.py
index 49c1ca45690..40d1b76ff25 100644
--- a/autotest/test_gwt_adv04.py
+++ b/autotest/test_gwt_adv04.py
@@ -1,9 +1,7 @@
 """
-MODFLOW 6 Autotest
 Test the advection schemes in the gwt advection package for two-dimensional
 injection of solute into the middle of a square grid.  The test will pass
 if the results are symmetric.
-
 """
 
 import os
@@ -11,14 +9,14 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["adv04a", "adv04b", "adv04c"]
+cases = ["adv04a", "adv04b", "adv04c"]
 scheme = ["upstream", "central", "tvd"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 21, 21
     nper = 1
     perlen = [5.0]
@@ -55,10 +53,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -228,13 +226,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -257,17 +253,13 @@ def eval_transport(sim):
     )
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_buy_solute_heat.py b/autotest/test_gwt_buy_solute_heat.py
index 173dfd60b04..d8f4c52740a 100644
--- a/autotest/test_gwt_buy_solute_heat.py
+++ b/autotest/test_gwt_buy_solute_heat.py
@@ -3,14 +3,13 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["gwtbuy"]
+from framework import TestFramework
 
+cases = ["gwtbuy"]
 
-def build_model(idx, dir):
 
+def build_models(idx, test):
     lx = 2000.0
     lz = 1000.0
 
@@ -35,10 +34,10 @@ def build_model(idx, dir):
     nouter, ninner = 100, 300
     hclose, rclose, relax = 1e-10, 1e-6, 0.97
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -331,7 +330,7 @@ def build_model(idx, dir):
 def make_plot(sim):
     print("making plots...")
     name = sim.name
-    ws = sim.simpath
+    ws = sim.workspace
     sim = flopy.mf6.MFSimulation.load(sim_ws=ws)
     gwfname = "flow"
     gwtsname = "salinity"
@@ -410,14 +409,12 @@ def make_plot(sim):
     return
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
+def check_output(idx, test):
     makeplot = False
     if makeplot:
-        make_plot(sim)
+        make_plot(test)
 
-    ws = sim.simpath
+    ws = test.workspace
     gwfname = "flow"
     gwtsname = "salinity"
     gwthname = "temperature"
@@ -448,7 +445,6 @@ def eval_transport(sim):
     densecalculated = 1000.0 + 0.7 * c - 0.375 * (t - 25.0)
 
     if not np.allclose(d, densecalculated):
-
         print("density is not correct")
         fname = os.path.join(ws, "a-dense.txt")
         np.savetxt(fname, d.reshape(200, 100))
@@ -462,17 +458,13 @@ def eval_transport(sim):
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_disu01.py b/autotest/test_gwt_disu01.py
index a9aad3dfdf6..1a457e402a7 100644
--- a/autotest/test_gwt_disu01.py
+++ b/autotest/test_gwt_disu01.py
@@ -1,9 +1,7 @@
 """
-MODFLOW 6 Autotest
 Two-dimensional injection of solute into the middle of a square grid.  The test will pass
 if the results are symmetric.  Based on test_gwt_adv04, this tests the disu package, which
 represents a regular MODFLOW grid.
-
 """
 
 import os
@@ -12,13 +10,13 @@
 import numpy as np
 import pytest
 from flopy.utils.gridutil import get_disu_kwargs
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["disu01a"]
+cases = ["disu01a"]
 
 
-def build_model(idx, dir, exe):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 21, 21
     nper = 1
     perlen = [5.0]
@@ -59,12 +57,12 @@ def get_nn(k, i, j):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name=exe, sim_ws=ws
+        sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
     # create tdis package
     tdis = flopy.mf6.ModflowTdis(
@@ -220,13 +218,11 @@ def get_nn(k, i, j):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -250,18 +246,13 @@ def eval_transport(sim):
     )
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    mf6 = targets.mf6
-    test = TestFramework()
-    test.build(lambda i, w: build_model(i, w, mf6), 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_dsp01.py b/autotest/test_gwt_dsp01.py
index 7d392cb225d..871871c89c5 100644
--- a/autotest/test_gwt_dsp01.py
+++ b/autotest/test_gwt_dsp01.py
@@ -3,14 +3,14 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["dsp01a", "dsp01b"]
+cases = ["dsp01a", "dsp01b"]
 xt3d = [False, True]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 100
     nper = 1
     perlen = [5.0]
@@ -38,10 +38,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -240,13 +240,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -370,33 +368,26 @@ def eval_transport(sim):
 
     # load the gwt observation file
     fname = gwtname + ".obs.csv"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     gwtobs = np.genfromtxt(fname, names=True, delimiter=",", deletechars="")
 
     # load the cnc observation file
     fname = gwtname + ".cnc.obs.csv"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     cncobs = np.genfromtxt(fname, names=True, delimiter=",", deletechars="")
 
     # ensure flow right face for first cell is equal to cnc flows
     errmsg = f"observations not equal:\n{gwtobs}\n{cncobs}"
     assert np.allclose(gwtobs["FLOW1"], -cncobs["CNC000"]), errmsg
 
-    # comment when done testing
-    # assert False
-
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_dsp01_fmi.py b/autotest/test_gwt_dsp01_fmi.py
index 424d467a702..8c09530efab 100644
--- a/autotest/test_gwt_dsp01_fmi.py
+++ b/autotest/test_gwt_dsp01_fmi.py
@@ -4,14 +4,14 @@
 import numpy as np
 import pytest
 from flopy.utils.binaryfile import write_budget, write_head
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["dsp01a_fmi", "dsp01b_fmi"]
+cases = ["dsp01a_fmi", "dsp01b_fmi"]
 xt3d = [False, True]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 100
     nper = 1
     perlen = [5.0]
@@ -39,10 +39,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -191,13 +191,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -320,17 +318,13 @@ def eval_transport(sim):
     ), "simulated concentrations do not match with known solution."
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_dsp01_gwtgwt.py b/autotest/test_gwt_dsp01_gwtgwt.py
index ab29408fa09..912bbdcf329 100644
--- a/autotest/test_gwt_dsp01_gwtgwt.py
+++ b/autotest/test_gwt_dsp01_gwtgwt.py
@@ -1,7 +1,5 @@
 """
-MODFLOW 6 Autotest
 Test basic dispersion for two coupled gwt models.
-
 """
 
 import os
@@ -9,12 +7,16 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["dsp01_gwtgwt"]
+cases = ["dsp01_gwtgwt"]
 gdelr = 1.0
 
+# solver settings
+nouter, ninner = 100, 300
+hclose, rclose, relax = 1e-6, 1e-6, 1.0
+
 
 def get_gwf_model(sim, gwfname, gwfpath, modelshape):
     nlay, nrow, ncol, xshift, yshift = modelshape
@@ -31,8 +33,6 @@ def get_gwf_model(sim, gwfname, gwfpath, modelshape):
         modelname=gwfname,
         save_flows=True,
     )
-    # this doesn't work here
-    # gwf.set_model_relative_path(gwfname)
 
     dis = flopy.mf6.ModflowGwfdis(
         gwf,
@@ -139,8 +139,7 @@ def get_gwt_model(sim, gwtname, gwtpath, modelshape):
     return gwt
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     # temporal discretization
     nper = 1
     perlen = [5.0]
@@ -151,7 +150,7 @@ def build_model(idx, dir):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=ws, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -268,10 +267,9 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-
+def check_output(idx, test):
     gwtname = "transport1"
-    fpth = os.path.join(sim.simpath, "transport1", f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, "transport1", f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -281,7 +279,7 @@ def eval_transport(sim):
         assert False, f'could not load data from "{fpth}"'
 
     gwtname = "transport2"
-    fpth = os.path.join(sim.simpath, "transport2", f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, "transport2", f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -298,18 +296,14 @@ def eval_transport(sim):
     assert abs(np.sum(conc1) + np.sum(conc2) - 100.0) < 1e-6
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 @pytest.mark.developmode
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_dsp01_noadv.py b/autotest/test_gwt_dsp01_noadv.py
index b5864f0bb19..f7577b073af 100644
--- a/autotest/test_gwt_dsp01_noadv.py
+++ b/autotest/test_gwt_dsp01_noadv.py
@@ -3,14 +3,14 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["dsp01a_noadv", "dsp01b_noadv"]
+cases = ["dsp01a_noadv", "dsp01b_noadv"]
 xt3d = [False, True]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 100
     nper = 1
     perlen = [5.0]
@@ -38,10 +38,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -135,13 +135,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -264,17 +262,13 @@ def eval_transport(sim):
     ), "simulated concentrations do not match with known solution."
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_dsp02.py b/autotest/test_gwt_dsp02.py
index 0b245e78058..192cafc8367 100644
--- a/autotest/test_gwt_dsp02.py
+++ b/autotest/test_gwt_dsp02.py
@@ -1,10 +1,8 @@
 """
-MODFLOW 6 Autotest
 Test the dispersion schemes in the gwt dispersion package for a one-dimensional
 model grid of triangular cells.  The cells are created by starting with a
 regular grid of squares and then cutting every cell into a triangle, except
 the first and last.
-
 """
 
 import os
@@ -13,10 +11,10 @@
 import flopy.utils.cvfdutil
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["dsp02a", "dsp02b"]
+cases = ["dsp02a", "dsp02b"]
 xt3d = [True, False]
 
 
@@ -65,7 +63,7 @@ def cvfd_to_cell2d(verts, iverts):
     return vertices, cell2d
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 100
     nper = 1
     perlen = [5.0]
@@ -87,10 +85,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -277,13 +275,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -709,21 +705,17 @@ def eval_transport(sim):
     creslist = [cres1, cres2]
 
     assert np.allclose(
-        creslist[sim.idxsim], conc
+        creslist[idx], conc
     ), "simulated concentrations do not match with known solution."
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_dsp03.py b/autotest/test_gwt_dsp03.py
index 7eb77075c88..7714e1e1f87 100644
--- a/autotest/test_gwt_dsp03.py
+++ b/autotest/test_gwt_dsp03.py
@@ -1,10 +1,8 @@
 """
-MODFLOW 6 Autotest
 Test the dispersion schemes in the gwt dispersion package for a three-dimensional
 model grid of triangular cells.  The cells are created by starting with a
 regular grid of squares and then cutting every cell into a triangle, except
 the first and last.
-
 """
 
 import os
@@ -13,10 +11,10 @@
 import flopy.utils.cvfdutil
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["dsp03a", "dsp03b"]
+cases = ["dsp03a", "dsp03b"]
 xt3d = [False, True]
 
 
@@ -65,7 +63,7 @@ def cvfd_to_cell2d(verts, iverts):
     return vertices, cell2d
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 5, 10, 20
     nper = 1
     delr = 1.0
@@ -93,10 +91,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -318,13 +316,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -427,30 +423,26 @@ def eval_transport(sim):
     # dimensional
     creslist = [cres1, cres2]
     ncellsperrow = cres1.shape[0]
-    assert np.allclose(creslist[sim.idxsim], conc[0, 0, 0:ncellsperrow]), (
+    assert np.allclose(creslist[idx], conc[0, 0, 0:ncellsperrow]), (
         "simulated concentrations do not match with known solution.",
-        creslist[sim.idxsim],
+        creslist[idx],
         conc[0, 0, -ncellsperrow:],
     )
-    assert np.allclose(creslist[sim.idxsim], conc[0, 0, -ncellsperrow:]), (
+    assert np.allclose(creslist[idx], conc[0, 0, -ncellsperrow:]), (
         "simulated concentrations do not match with known solution.",
-        creslist[sim.idxsim],
+        creslist[idx],
         conc[0, 0, -ncellsperrow:],
     )
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_dsp04.py b/autotest/test_gwt_dsp04.py
index aa9d1b02206..ab14cfb8022 100644
--- a/autotest/test_gwt_dsp04.py
+++ b/autotest/test_gwt_dsp04.py
@@ -3,15 +3,15 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
 # test dispersion without and with xt3d
-ex = ["dsp04a", "dsp04b"]
+cases = ["dsp04a", "dsp04b"]
 xt3d = [None, True]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 21, 21
     nper = 1
     perlen = [5.0]
@@ -45,10 +45,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -222,13 +222,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -251,17 +249,13 @@ def eval_transport(sim):
     )
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_dsp05_noadv.py b/autotest/test_gwt_dsp05_noadv.py
index 93af5361d4d..e5a2f0675f8 100644
--- a/autotest/test_gwt_dsp05_noadv.py
+++ b/autotest/test_gwt_dsp05_noadv.py
@@ -1,23 +1,21 @@
 """
-MODFLOW 6 Autotest
 Test variable layer thicknesses with a diffusion problem and constant
 concentrations on the top and bottom to make sure the resulting concentration
 field is linear from top to bottom.
-
 """
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["dsp05a_noadv", "dsp01b_noadv"]
+cases = ["dsp05a_noadv", "dsp01b_noadv"]
 xt3d = [False, True]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 5, 1, 1
     nper = 1
     perlen = [5.0]
@@ -36,10 +34,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -133,13 +131,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -161,17 +157,13 @@ def eval_transport(sim):
     assert np.allclose(cres, conc.flatten()), msg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_fmi01.py b/autotest/test_gwt_fmi01.py
index fcf6a9e0251..93d6a344b06 100644
--- a/autotest/test_gwt_fmi01.py
+++ b/autotest/test_gwt_fmi01.py
@@ -5,14 +5,14 @@
 import pytest
 from flopy.utils.binaryfile import write_budget, write_head
 from flopy.utils.gridutil import uniform_flow_field
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["fmi01a_fc"]
+cases = ["fmi01a_fc"]
 xt3d = [False, True]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 3
     nper = 1
     perlen = [1.0]
@@ -38,10 +38,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -173,13 +173,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     cobj = flopy.utils.HeadFile(fpth, precision="double", text="CONCENTRATION")
     conc = cobj.get_data()
 
@@ -191,17 +189,13 @@ def eval_transport(sim):
     assert np.allclose(cres, conc), errmsg
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_fmi02.py b/autotest/test_gwt_fmi02.py
index 545428e55e9..6271c115ae5 100644
--- a/autotest/test_gwt_fmi02.py
+++ b/autotest/test_gwt_fmi02.py
@@ -1,4 +1,4 @@
-# tests to ability to run flow model first followed by transport model
+"""Tests to ability to run flow model first followed by transport model"""
 
 import os
 
diff --git a/autotest/test_gwt_henry.py b/autotest/test_gwt_henry.py
index 19d3e93fd40..2bbc4b71fc9 100644
--- a/autotest/test_gwt_henry.py
+++ b/autotest/test_gwt_henry.py
@@ -3,14 +3,13 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["henry01"]
+from framework import TestFramework
 
+cases = ["henry01"]
 
-def build_model(idx, dir):
 
+def build_models(idx, test):
     lx = 2.0
     lz = 1.0
 
@@ -35,10 +34,10 @@ def build_model(idx, dir):
     nouter, ninner = 100, 300
     hclose, rclose, relax = 1e-10, 1e-6, 0.97
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -231,13 +230,11 @@ def chd_value(k):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -289,17 +286,13 @@ def eval_transport(sim):
     )
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_henry_gwtgwt.py b/autotest/test_gwt_henry_gwtgwt.py
new file mode 100644
index 00000000000..362f627f525
--- /dev/null
+++ b/autotest/test_gwt_henry_gwtgwt.py
@@ -0,0 +1,439 @@
+import os
+
+import flopy
+import numpy as np
+import pytest
+
+from framework import TestFramework
+
+cases = ["henry01-gwtgwt-ups", "henry01-gwtgwt-cen", "henry01-gwtgwt-tvd"]
+advection_scheme = ["UPSTREAM", "CENTRAL", "TVD"]
+
+lx = 2.0
+lz = 1.0
+
+nlay = 10
+nrow = 1
+ncol = 20
+ncol_sub = 10
+nper = 1
+delr = lx / ncol
+delc = 1.0
+top = 1.0
+delz = lz / nlay
+botm = list(top - np.arange(delz, nlay * delz + delz, delz))
+
+perlen = [0.5]
+nstp = [500]
+tsmult = [1.0]
+steady = [True]
+tdis_rc = []
+for i in range(nper):
+    tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
+
+nouter, ninner = 100, 300
+hclose, rclose, relax = 1e-10, 1e-9, 0.97
+
+# tolerance for concentrations, relate to hclose and rclose
+conc_tol = 1e-06
+
+hc = 864.0
+
+
+def get_gwf_model(sim, model_shape, model_desc):
+    nlay, nrow, ncol = model_shape
+
+    # create gwf model
+    gwfname = "gwf_" + model_desc
+    gwtname = "gwt_" + model_desc
+
+    gwf = flopy.mf6.ModflowGwf(sim, modelname=gwfname)
+
+    xoff = 0.0
+    yoff = 0.0
+    if model_desc == "right":
+        xoff = ncol * delr
+
+    _ = flopy.mf6.ModflowGwfdis(
+        gwf,
+        nlay=nlay,
+        nrow=nrow,
+        ncol=ncol,
+        delr=delr,
+        delc=delc,
+        top=top,
+        botm=botm,
+        xorigin=xoff,
+        yorigin=yoff,
+    )
+
+    # initial conditions
+    _ = flopy.mf6.ModflowGwfic(gwf, strt=1.0)
+
+    # node property flow
+    _ = flopy.mf6.ModflowGwfnpf(
+        gwf,
+        xt3doptions=False,
+        save_flows=True,
+        save_specific_discharge=True,
+        icelltype=0,
+        k=hc,
+    )
+
+    pd = [(0, 0.7, 0.0, gwtname, "none")]
+    _ = flopy.mf6.ModflowGwfbuy(
+        gwf,
+        packagedata=pd,
+    )
+
+    def chd_value(k):
+        # depth = k * delz + 0.5 * delz
+        # hf = top + 0.025 * depth
+        hf = top
+        return hf
+
+    # chd files for right model
+    if not model_desc == "left":
+        chdlist1 = []
+        for k in range(nlay):
+            chdlist1.append([(k, 0, ncol - 1), chd_value(k), 35.0])
+        _ = flopy.mf6.ModflowGwfchd(
+            gwf,
+            stress_period_data=chdlist1,
+            print_input=True,
+            print_flows=True,
+            save_flows=False,
+            pname="CHD-1",
+            auxiliary="CONCENTRATION",
+            filename=f"{gwfname}.chd",
+        )
+
+    # WEL for left model
+    if not model_desc == "right":
+        wellist1 = []
+        qwell = 5.7024 / nlay
+        for k in range(nlay):
+            wellist1.append([(k, 0, 0), qwell, 0.0])
+        _ = flopy.mf6.ModflowGwfwel(
+            gwf,
+            stress_period_data=wellist1,
+            print_input=True,
+            print_flows=True,
+            save_flows=False,
+            pname="WEL-1",
+            auxiliary="CONCENTRATION",
+            filename=f"{gwfname}.wel",
+        )
+
+    # output control
+    _ = flopy.mf6.ModflowGwfoc(
+        gwf,
+        budget_filerecord=f"{gwfname}.cbc",
+        head_filerecord=f"{gwfname}.hds",
+        headprintrecord=[("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")],
+        saverecord=[("HEAD", "LAST"), ("BUDGET", "LAST")],
+        printrecord=[("HEAD", "LAST"), ("BUDGET", "LAST")],
+    )
+
+    return gwf
+
+
+def get_gwt_model(sim, model_shape, model_desc, adv_scheme):
+    nlay, nrow, ncol = model_shape
+
+    # create gwf model
+    gwtname = "gwt_" + model_desc
+
+    # create gwt model
+    gwt = flopy.mf6.ModflowGwt(sim, modelname=gwtname)
+
+    xoff = 0.0
+    yoff = 0.0
+    if model_desc == "right":
+        xoff = ncol * delr
+
+    _ = flopy.mf6.ModflowGwtdis(
+        gwt,
+        nlay=nlay,
+        nrow=nrow,
+        ncol=ncol,
+        delr=delr,
+        delc=delc,
+        top=top,
+        botm=botm,
+        xorigin=xoff,
+        yorigin=yoff,
+    )
+
+    # initial conditions
+    _ = flopy.mf6.ModflowGwtic(gwt, strt=35.0, filename=f"{gwtname}.ic")
+
+    # advection
+    _ = flopy.mf6.ModflowGwtadv(
+        gwt, scheme=adv_scheme, filename=f"{gwtname}.adv"
+    )
+
+    # dispersion
+    diffc = 0.57024
+    _ = flopy.mf6.ModflowGwtdsp(
+        gwt,
+        xt3d_off=True,
+        diffc=diffc,
+        # alh=0., alv=0., ath=0., atv=0.,
+        filename=f"{gwtname}.dsp",
+    )
+
+    # mass storage and transfer
+    porosity = 0.35
+    _ = flopy.mf6.ModflowGwtmst(
+        gwt, porosity=porosity, filename=f"{gwtname}.sto"
+    )
+
+    # sources
+    if model_desc == "right":
+        sourcerecarray = [
+            ("CHD-1", "AUX", "CONCENTRATION"),
+        ]
+    elif model_desc == "left":
+        sourcerecarray = [
+            ("WEL-1", "AUX", "CONCENTRATION"),
+        ]
+    elif model_desc == "ref":
+        sourcerecarray = [
+            ("WEL-1", "AUX", "CONCENTRATION"),
+            ("CHD-1", "AUX", "CONCENTRATION"),
+        ]
+
+    _ = flopy.mf6.ModflowGwtssm(
+        gwt, sources=sourcerecarray, filename=f"{gwtname}.ssm"
+    )
+
+    # output control
+    _ = flopy.mf6.ModflowGwtoc(
+        gwt,
+        budget_filerecord=f"{gwtname}.cbc",
+        concentration_filerecord=f"{gwtname}.ucn",
+        concentrationprintrecord=[
+            ("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")
+        ],
+        saverecord=[("CONCENTRATION", "ALL")],
+        printrecord=[("CONCENTRATION", "LAST"), ("BUDGET", "LAST")],
+    )
+
+    return gwt
+
+
+def build_models(idx, test):
+    name = cases[idx]
+    print("RUINNING: ", name, advection_scheme[idx])
+
+    # build MODFLOW 6 files
+    ws = test.workspace
+    sim = flopy.mf6.MFSimulation(
+        sim_name=name,
+        version="mf6",
+        exe_name="mf6",
+        sim_ws=ws,
+    )
+    # create tdis package
+    tdis = flopy.mf6.ModflowTdis(
+        sim, time_units="DAYS", nper=nper, perioddata=tdis_rc
+    )
+
+    # create flow models and GWF-GWF exchange
+    gwf_ref = get_gwf_model(sim, (nlay, nrow, ncol), "ref")
+    gwf_left = get_gwf_model(sim, (nlay, nrow, ncol_sub), "left")
+    gwf_right = get_gwf_model(sim, (nlay, nrow, ncol_sub), "right")
+
+    imsgwf_ref = flopy.mf6.ModflowIms(
+        sim,
+        print_option="ALL",
+        outer_dvclose=hclose,
+        outer_maximum=nouter,
+        under_relaxation="NONE",
+        inner_maximum=ninner,
+        inner_dvclose=hclose,
+        rcloserecord=rclose,
+        linear_acceleration="BICGSTAB",
+        scaling_method="NONE",
+        reordering_method="NONE",
+        relaxation_factor=relax,
+        filename="gwf.ims",
+    )
+    sim.register_ims_package(
+        imsgwf_ref, [gwf_ref.name, gwf_left.name, gwf_right.name]
+    )
+
+    angldegx = 0.0
+    cdist = delr
+    gwfgwf_data = [
+        [
+            (ilay, 0, ncol_sub - 1),
+            (ilay, 0, 0),
+            1,
+            0.5 * delr,
+            0.5 * delr,
+            delc,
+            angldegx,
+            cdist,
+        ]
+        for ilay in range(nlay)
+    ]
+    _ = flopy.mf6.ModflowGwfgwf(
+        sim,
+        exgtype="GWF6-GWF6",
+        nexg=len(gwfgwf_data),
+        exgmnamea=gwf_left.name,
+        exgmnameb=gwf_right.name,
+        exchangedata=gwfgwf_data,
+        auxiliary=["ANGLDEGX", "CDIST"],
+        filename="leftright.gwfgwf",
+        dev_interfacemodel_on=True,
+    )
+
+    # create transport models and GWT-GWT exchange
+    gwt_ref = get_gwt_model(
+        sim, (nlay, nrow, ncol), "ref", advection_scheme[idx]
+    )
+    gwt_left = get_gwt_model(
+        sim, (nlay, nrow, ncol_sub), "left", advection_scheme[idx]
+    )
+    gwt_right = get_gwt_model(
+        sim, (nlay, nrow, ncol_sub), "right", advection_scheme[idx]
+    )
+
+    imsgwt_ref = flopy.mf6.ModflowIms(
+        sim,
+        print_option="ALL",
+        outer_dvclose=hclose,
+        outer_maximum=nouter,
+        under_relaxation="NONE",
+        inner_maximum=ninner,
+        inner_dvclose=hclose,
+        rcloserecord=rclose,
+        linear_acceleration="BICGSTAB",
+        scaling_method="NONE",
+        reordering_method="NONE",
+        relaxation_factor=relax,
+        filename="gwt.ims",
+    )
+    sim.register_ims_package(
+        imsgwt_ref, [gwt_ref.name, gwt_left.name, gwt_right.name]
+    )
+
+    _ = flopy.mf6.ModflowGwtgwt(
+        sim,
+        exgtype="GWT6-GWT6",
+        gwfmodelname1=gwf_left.name,
+        gwfmodelname2=gwf_right.name,
+        adv_scheme=advection_scheme[idx],
+        nexg=len(gwfgwf_data),
+        exgmnamea=gwt_left.name,
+        exgmnameb=gwt_right.name,
+        exchangedata=gwfgwf_data,
+        auxiliary=["ANGLDEGX", "CDIST"],
+        filename="leftright.gwtgwt",
+    )
+
+    # Finally connect flow to transport: GWF GWT exchange
+    _ = flopy.mf6.ModflowGwfgwt(
+        sim,
+        exgtype="GWF6-GWT6",
+        exgmnamea=gwf_ref.name,
+        exgmnameb=gwt_ref.name,
+        filename="ref.gwfgwt",
+    )
+
+    _ = flopy.mf6.ModflowGwfgwt(
+        sim,
+        exgtype="GWF6-GWT6",
+        exgmnamea=gwf_left.name,
+        exgmnameb=gwt_left.name,
+        filename="left.gwfgwt",
+    )
+
+    _ = flopy.mf6.ModflowGwfgwt(
+        sim,
+        exgtype="GWF6-GWT6",
+        exgmnamea=gwf_right.name,
+        exgmnameb=gwt_right.name,
+        filename="right.gwfgwt",
+    )
+
+    return sim, None
+
+
+def check_output(idx, test):
+    fpth = os.path.join(test.workspace, "gwf_ref.hds")
+    hds = flopy.utils.HeadFile(fpth)
+    heads = hds.get_data()
+
+    fpth = os.path.join(test.workspace, "gwf_left.hds")
+    hds = flopy.utils.HeadFile(fpth)
+    heads_left = hds.get_data()
+
+    fpth = os.path.join(test.workspace, "gwf_right.hds")
+    hds = flopy.utils.HeadFile(fpth)
+    heads_right = hds.get_data()
+
+    heads_gwfgwf = np.append(heads_left, heads_right, axis=2)
+
+    # compare heads
+    maxdiff = np.amax(abs(heads - heads_gwfgwf))
+    assert (
+        maxdiff < 10 * hclose
+    ), "Max. head diff. {} should \
+        be within solver tolerance (x10): {}".format(
+        maxdiff, 10 * hclose
+    )
+
+    fpth = os.path.join(test.workspace, f"gwt_ref.ucn")
+    try:
+        cobj = flopy.utils.HeadFile(
+            fpth, precision="double", text="CONCENTRATION"
+        )
+        conc_ref = cobj.get_data()
+    except:
+        assert False, f'could not load data from "{fpth}"'
+
+    fpth = os.path.join(test.workspace, f"gwt_left.ucn")
+    try:
+        cobj = flopy.utils.HeadFile(
+            fpth, precision="double", text="CONCENTRATION"
+        )
+        conc_left = cobj.get_data()
+    except:
+        assert False, f'could not load data from "{fpth}"'
+
+    fpth = os.path.join(test.workspace, f"gwt_right.ucn")
+    try:
+        cobj = flopy.utils.HeadFile(
+            fpth, precision="double", text="CONCENTRATION"
+        )
+        conc_right = cobj.get_data()
+    except:
+        assert False, f'could not load data from "{fpth}"'
+
+    # merge left and right concentrations for bottom layer:
+    conc_gwtgwt = np.append(conc_left, conc_right, axis=2)
+
+    maxdiff = np.amax(abs(conc_gwtgwt - conc_ref))
+    assert (
+        maxdiff < conc_tol
+    ), "Max. concentration diff. {} should \
+        be within solver tolerance (x10): {}".format(
+        maxdiff, conc_tol
+    )
+
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+@pytest.mark.developmode
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+    )
+    test.run()
diff --git a/autotest/test_gwt_henry_nr.py b/autotest/test_gwt_henry_nr.py
index 3c652cd7ae0..e7dac23d84e 100644
--- a/autotest/test_gwt_henry_nr.py
+++ b/autotest/test_gwt_henry_nr.py
@@ -1,19 +1,21 @@
-# This is the Henry, Newton-Raphson problem described by Langevin et al (2020)
-# with a 20 by 40 grid instead of the 40 by 80 grid described in the paper.
-# There is freshwater inflow on the left and a sloping sea boundary on the
-# right with moves up and down according to a simple sine function.  GHBs
-# and DRNs alternate and move up and down along the boundary to represent
-# the effects of tides on the aquifer.
+"""
+This is the Henry, Newton-Raphson problem described by Langevin et al (2020)
+with a 20 by 40 grid instead of the 40 by 80 grid described in the paper.
+There is freshwater inflow on the left and a sloping sea boundary on the
+right with moves up and down according to a simple sine function.  GHBs
+and DRNs alternate and move up and down along the boundary to represent
+the effects of tides on the aquifer.
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["henrynr01"]
+cases = ["henrynr01"]
 
 # global model variables
 nlay = 20
@@ -66,10 +68,9 @@ def sinfunc(a, b, c, d, x):
     return a * np.sin(b * (x - c)) + d
 
 
-def build_model(idx, dir):
-
-    ws = dir
-    name = ex[idx]
+def build_models(idx, test):
+    ws = test.workspace
+    name = cases[idx]
 
     nrow = 1
     delr = lx / ncol
@@ -377,7 +378,7 @@ def make_plot(sim, headall, concall):
     print("making plots...")
 
     name = sim.name
-    ws = sim.simpath
+    ws = sim.workspace
     sim = flopy.mf6.MFSimulation.load(sim_ws=ws)
     gwfname = "gwf_" + name
     gwtname = "gwt_" + name
@@ -461,11 +462,9 @@ def make_plot(sim, headall, concall):
     plt.savefig(fname, bbox_inches="tight")
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = sim.name
-    ws = sim.simpath
+def check_output(idx, test):
+    name = test.name
+    ws = test.workspace
     gwfname = "gwf_" + name
     gwtname = "gwt_" + name
 
@@ -523,22 +522,18 @@ def eval_transport(sim):
 
     makeplot = False
     if makeplot:
-        make_plot(sim, head, conc)
+        make_plot(test, head, conc)
         assert False
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_henry_openclose.py b/autotest/test_gwt_henry_openclose.py
index 86d8ff5b075..bdc1c6e3725 100644
--- a/autotest/test_gwt_henry_openclose.py
+++ b/autotest/test_gwt_henry_openclose.py
@@ -3,14 +3,13 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["henry_ext"]
+from framework import TestFramework
 
+cases = ["henry_ext"]
 
-def build_model(idx, dir):
 
+def build_models(idx, test):
     lx = 2.0
     lz = 1.0
 
@@ -35,10 +34,10 @@ def build_model(idx, dir):
     nouter, ninner = 100, 300
     hclose, rclose, relax = 1e-10, 1e-6, 0.97
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -234,13 +233,11 @@ def chd_value(k):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -292,17 +289,13 @@ def eval_transport(sim):
     )
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_ims_issue655.py b/autotest/test_gwt_ims_issue655.py
index 497c2585bad..7cbb8b42122 100644
--- a/autotest/test_gwt_ims_issue655.py
+++ b/autotest/test_gwt_ims_issue655.py
@@ -3,7 +3,6 @@
 side GWT boundary conditions. Versions 6.2.1 and earlier failed because of a
 divide by zero error in IMS. This test confirms the fix implemented as part
 of the version 6.2.2 release that addressed Issue 655.
-
 """
 
 import os
@@ -11,10 +10,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["issue655a", "issue655b"]
+cases = ["issue655a", "issue655b"]
 newton = [
     False,
     True,
@@ -25,7 +24,7 @@
 nlay, nrow, ncol = 1, 11, 11
 
 
-def build_model(idx, ws):
+def build_models(idx, test):
     nper = 1
     perlen = [1000.0]
     nstp = [5]
@@ -65,11 +64,11 @@ def build_model(idx, ws):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
     sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
+        sim_name=name, version="mf6", exe_name="mf6", sim_ws=test.workspace
     )
     # create tdis package
     tdis = flopy.mf6.ModflowTdis(
@@ -249,21 +248,19 @@ def build_model(idx, ws):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
     gwfname = "gwf_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwfname}.hds")
+    fpth = os.path.join(test.workspace, f"{gwfname}.hds")
     try:
         hobj = flopy.utils.HeadFile(fpth, precision="double")
         head = hobj.get_alldata().flatten()
     except:
         assert False, f'could not load data from "{fpth}"'
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -292,17 +289,13 @@ def eval_transport(sim):
     #     vold = v
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_ist01.py b/autotest/test_gwt_ist01.py
index 6587941a2d3..b9fd366206c 100644
--- a/autotest/test_gwt_ist01.py
+++ b/autotest/test_gwt_ist01.py
@@ -1,7 +1,6 @@
 """
 Test the IST Package with a one cell model with water added and then
 removed.
-
 """
 
 import os
@@ -9,10 +8,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["ist01"]
+cases = ["ist01"]
 laytyp = [1]
 ss = [1.0e-10]
 sy = [0.1]
@@ -22,8 +21,7 @@
 nlay, nrow, ncol = 1, 1, 1
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     perlen = [
         2.0,
     ]
@@ -44,10 +42,10 @@ def build_model(idx, dir):
     for id in range(nper):
         tdis_rc.append((perlen[id], nstp[id], tsmult[id]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -222,25 +220,23 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwtname = "gwt_" + name
     gwfname = "gwf_" + name
 
     # head
-    fpth = os.path.join(sim.simpath, f"{gwfname}.hds")
+    fpth = os.path.join(test.workspace, f"{gwfname}.hds")
     hobj = flopy.utils.HeadFile(fpth, precision="double")
     head = hobj.get_alldata().flatten()
 
     # mobile concentration
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     cobj = flopy.utils.HeadFile(fpth, precision="double", text="CONCENTRATION")
     conc = cobj.get_alldata().flatten()
 
     # immobile concentration
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ist.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ist.ucn")
     try:
         cobj = flopy.utils.HeadFile(fpth, precision="double", text="CIM")
         cim = cobj.get_alldata().flatten()
@@ -248,7 +244,7 @@ def eval_transport(sim):
         assert False, f'could not load data from "{fpth}"'
 
     # budget
-    fpth = os.path.join(sim.simpath, f"{gwtname}.cbc")
+    fpth = os.path.join(test.workspace, f"{gwtname}.cbc")
     try:
         bobj = flopy.utils.CellBudgetFile(fpth, precision="double")
         print(bobj.get_unique_record_names())
@@ -267,17 +263,13 @@ def eval_transport(sim):
         assert np.allclose(rate_sim, rate_calc), msg
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_ist02.py b/autotest/test_gwt_ist02.py
index 927ee082f39..17cb6741890 100644
--- a/autotest/test_gwt_ist02.py
+++ b/autotest/test_gwt_ist02.py
@@ -16,10 +16,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["ist02"]
+cases = ["ist02"]
 nlay, nrow, ncol = 1, 1, 300
 
 mt3d_times = np.arange(1.0, 51.0, 1.0)
@@ -79,7 +79,7 @@
 )
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     perlen = [20.0, 30.0]
     nper = len(perlen)
     nstp = [100, 100]
@@ -98,10 +98,10 @@ def build_model(idx, dir):
     for id in range(nper):
         tdis_rc.append((perlen[id], nstp[id], tsmult[id]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -321,7 +321,7 @@ def build_model(idx, dir):
 def make_plot(sim):
     print("making plots...")
     name = sim.name
-    ws = sim.simpath
+    ws = sim.workspace
     sim = flopy.mf6.MFSimulation.load(sim_ws=ws)
     gwfname = "gwf_" + name
     gwtname = "gwt_" + name
@@ -344,22 +344,18 @@ def make_plot(sim):
     fname = os.path.join(ws, gwtname + ".png")
     plt.savefig(fname)
 
-    return
-
-
-def eval_transport(sim):
-    print("evaluating transport...")
 
+def check_output(idx, test):
     makeplot = False
     if makeplot:
-        make_plot(sim)
+        make_plot(test)
 
-    name = sim.name
+    name = test.name
     gwtname = "gwt_" + name
     gwfname = "gwf_" + name
 
     # load the observed concentrations in column 300
-    fname = os.path.join(sim.simpath, gwtname + ".obs.csv")
+    fname = os.path.join(test.workspace, gwtname + ".obs.csv")
     assert os.path.isfile(fname), f"file not found: {fname}"
     simvals = np.genfromtxt(fname, names=True, delimiter=",", deletechars="")
 
@@ -380,17 +376,13 @@ def eval_transport(sim):
     assert success, "Conc difference between mf6 and mt3d > 0.05"
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_lkt01.py b/autotest/test_gwt_lkt01.py
index 4971e5c9412..f066f47b394 100644
--- a/autotest/test_gwt_lkt01.py
+++ b/autotest/test_gwt_lkt01.py
@@ -1,20 +1,22 @@
-# Simple one-layer model with a lak.  Purpose is to test a constant
-# stage and constant concentration lake with a value of 100.  The aquifer
-# starts with a concentration of zero, but the values grow as the lake
-# leaks into the aquifer.
+"""
+Simple one-layer model with a lak.  Purpose is to test a constant
+stage and constant concentration lake with a value of 100.  The aquifer
+starts with a concentration of zero, but the values grow as the lake
+leaks into the aquifer.
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["lkt_01"]
+from framework import DNODATA, TestFramework
 
+cases = ["lkt_01"]
 
-def build_model(idx, dir):
+
+def build_models(idx, test):
     lx = 5.0
     lz = 1.0
     nlay = 1
@@ -45,10 +47,10 @@ def build_model(idx, dir):
     nouter, ninner = 700, 300
     hclose, rclose, relax = 1e-8, 1e-6, 0.97
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -127,20 +129,20 @@ def build_model(idx, dir):
     )
 
     nlakeconn = 3  # note: this is the number of connectiosn for a lake, not total number of connections
-    # pak_data = [lakeno, strt, nlakeconn, CONC, dense, boundname]
+    # pak_data = [ifno, strt, nlakeconn, CONC, dense, boundname]
     pak_data = [(0, -0.4, nlakeconn, 0.0, 1025.0)]
 
     connlen = connwidth = delr / 2.0
     con_data = []
-    # con_data=(lakeno,iconn,(cellid),claktype,bedleak,belev,telev,connlen,connwidth )
+    # con_data=(ifno,iconn,(cellid),claktype,bedleak,belev,telev,connlen,connwidth )
     con_data.append(
-        (0, 0, (0, 0, 1), "HORIZONTAL", "None", 10, 10, connlen, connwidth)
+        (0, 0, (0, 0, 1), "HORIZONTAL", DNODATA, 10, 10, connlen, connwidth)
     )
     con_data.append(
-        (0, 1, (0, 0, 3), "HORIZONTAL", "None", 10, 10, connlen, connwidth)
+        (0, 1, (0, 0, 3), "HORIZONTAL", DNODATA, 10, 10, connlen, connwidth)
     )
     con_data.append(
-        (0, 2, (0, 0, 2), "VERTICAL", "None", 10, 10, connlen, connwidth)
+        (0, 2, (0, 0, 2), "VERTICAL", DNODATA, 10, 10, connlen, connwidth)
     )
     p_data = [
         (0, "STATUS", "CONSTANT"),
@@ -334,7 +336,7 @@ def build_model(idx, dir):
 
 
 def get_mfsim(testsim):
-    ws = testsim.simpath
+    ws = testsim.workspace
     sim = flopy.mf6.MFSimulation.load(sim_ws=ws)
     return sim
 
@@ -355,17 +357,15 @@ def eval_csv_information(testsim):
     ), f"Lake package does not have zero mass balance error: {result}"
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # eval csv files
-    eval_csv_information(sim)
+    eval_csv_information(test)
 
     # ensure lake concentrations were saved
-    name = sim.name
+    name = test.name
     gwtname = "gwt_" + name
     fname = gwtname + ".lkt.bin"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
 
     # load the lake concentrations and make sure all values are 100.
@@ -376,7 +376,7 @@ def eval_results(sim):
 
     # load the aquifer concentrations and make sure all values are correct
     fname = gwtname + ".ucn"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     cobj = flopy.utils.HeadFile(fname, text="CONCENTRATION")
     caq = cobj.get_alldata()
     answer = np.array(
@@ -387,7 +387,7 @@ def eval_results(sim):
     ), f"{caq[-1].flatten()} {answer}"
 
     # lkt observation results
-    fpth = os.path.join(sim.simpath, gwtname + ".lkt.obs.csv")
+    fpth = os.path.join(test.workspace, gwtname + ".lkt.obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -429,21 +429,14 @@ def eval_results(sim):
     answer = np.ones(10) * -216.3934
     assert np.allclose(res, answer), f"{res} {answer}"
 
-    # uncomment when testing
-    # assert False
-
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_lkt02.py b/autotest/test_gwt_lkt02.py
index 616fb514397..a4368b16f95 100644
--- a/autotest/test_gwt_lkt02.py
+++ b/autotest/test_gwt_lkt02.py
@@ -1,18 +1,20 @@
-# Simple one-layer model with a lak.  Purpose is to test outlets that
-# move solute from one lake to another.
+"""
+Simple one-layer model with a lak.  Purpose is to test outlets that
+move solute from one lake to another.
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["lkt_02"]
+from framework import DNODATA, TestFramework
 
+cases = ["lkt_02"]
 
-def build_model(idx, dir):
+
+def build_models(idx, test):
     lx = 7.0
     lz = 1.0
     nlay = 1
@@ -43,10 +45,10 @@ def build_model(idx, dir):
     nouter, ninner = 700, 300
     hclose, rclose, relax = 1e-8, 1e-6, 0.97
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -124,7 +126,7 @@ def build_model(idx, dir):
         filename=f"{gwfname}.chd",
     )
 
-    # pak_data = [lakeno, strt, nlakeconn, CONC, dense, boundname]
+    # pak_data = [ifno, strt, nlakeconn, CONC, dense, boundname]
     pak_data = [
         (0, -0.4, 2, 0.0, 1025.0),
         (1, -0.4, 1, 0.0, 1025.0),
@@ -133,24 +135,24 @@ def build_model(idx, dir):
 
     connlen = connwidth = delr / 2.0
     con_data = []
-    # con_data=(lakeno,iconn,(cellid),claktype,bedleak,belev,telev,connlen,connwidth )
+    # con_data=(ifno,iconn,(cellid),claktype,bedleak,belev,telev,connlen,connwidth )
     # lake 1
     con_data.append(
-        (0, 0, (0, 0, 1), "HORIZONTAL", "None", 10, 10, connlen, connwidth)
+        (0, 0, (0, 0, 1), "HORIZONTAL", DNODATA, 10, 10, connlen, connwidth)
     )
     con_data.append(
-        (0, 1, (0, 0, 2), "VERTICAL", "None", 10, 10, connlen, connwidth)
+        (0, 1, (0, 0, 2), "VERTICAL", DNODATA, 10, 10, connlen, connwidth)
     )
     # lake 2
     con_data.append(
-        (1, 0, (0, 0, 3), "VERTICAL", "None", 10, 10, connlen, connwidth)
+        (1, 0, (0, 0, 3), "VERTICAL", DNODATA, 10, 10, connlen, connwidth)
     )
     # lake 3
     con_data.append(
-        (2, 0, (0, 0, 4), "VERTICAL", "None", 10, 10, connlen, connwidth)
+        (2, 0, (0, 0, 4), "VERTICAL", DNODATA, 10, 10, connlen, connwidth)
     )
     con_data.append(
-        (2, 1, (0, 0, 5), "HORIZONTAL", "None", 10, 10, connlen, connwidth)
+        (2, 1, (0, 0, 5), "HORIZONTAL", DNODATA, 10, 10, connlen, connwidth)
     )
 
     p_data = [
@@ -352,14 +354,12 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # ensure lake concentrations were saved
-    name = sim.name
+    name = test.name
     gwtname = "gwt_" + name
     fname = gwtname + ".lkt.bin"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
 
     # load the lake concentrations and make sure all values are correct
@@ -370,7 +370,7 @@ def eval_results(sim):
 
     # load the aquifer concentrations and make sure all values are correct
     fname = gwtname + ".ucn"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     cobj = flopy.utils.HeadFile(fname, text="CONCENTRATION")
     caq = cobj.get_data()
     answer = np.array(
@@ -387,7 +387,7 @@ def eval_results(sim):
     assert np.allclose(caq, answer), f"{caq.flatten()} {answer}"
 
     # lkt observation results
-    fpth = os.path.join(sim.simpath, gwtname + ".lkt.obs.csv")
+    fpth = os.path.join(test.workspace, gwtname + ".lkt.obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -455,7 +455,7 @@ def eval_results(sim):
 
     # load the lake budget file
     fname = gwtname + ".lkt.bud"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     bobj = flopy.utils.CellBudgetFile(fname, precision="double", verbose=False)
     # check the flow-ja-face terms
@@ -482,21 +482,14 @@ def eval_results(sim):
     for dtname, dttype in dt:
         assert np.allclose(res[dtname], answer[dtname]), f"{res} {answer}"
 
-    # uncomment when testing
-    # assert False
-
-
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=0
-        ),
-        ws,
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_lkt03.py b/autotest/test_gwt_lkt03.py
index efd98105085..43272fda679 100644
--- a/autotest/test_gwt_lkt03.py
+++ b/autotest/test_gwt_lkt03.py
@@ -1,18 +1,20 @@
-# Simple one-layer model with a lak.  Purpose is to test the lak flow terms
-# such as rainfall to make sure mixing is calculated correctly.
+"""
+Simple one-layer model with a lak.  Purpose is to test the lak flow terms
+such as rainfall to make sure mixing is calculated correctly.
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["lkt_03"]
+from framework import DNODATA, TestFramework
 
+cases = ["lkt_03"]
 
-def build_model(idx, dir):
+
+def build_models(idx, test):
     lx = 7.0
     lz = 1.0
     nlay = 1
@@ -41,10 +43,10 @@ def build_model(idx, dir):
     nouter, ninner = 700, 300
     hclose, rclose, relax = 1e-8, 1e-6, 0.97
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -122,7 +124,7 @@ def build_model(idx, dir):
         filename=f"{gwfname}.chd",
     )
 
-    # pak_data = [lakeno, strt, nlakeconn, CONC, dense, boundname]
+    # pak_data = [ifno, strt, nlakeconn, CONC, dense, boundname]
     pak_data = [
         (0, 0.0, 1, 0.0, 1025.0),
         (1, 0.0, 1, 0.0, 1025.0),
@@ -131,18 +133,18 @@ def build_model(idx, dir):
 
     connlen = connwidth = delr / 2.0
     con_data = []
-    # con_data=(lakeno,iconn,(cellid),claktype,bedleak,belev,telev,connlen,connwidth )
+    # con_data=(ifno,iconn,(cellid),claktype,bedleak,belev,telev,connlen,connwidth )
     # lake 1
     con_data.append(
-        (0, 0, (0, 0, 2), "VERTICAL", "None", 10, 10, connlen, connwidth)
+        (0, 0, (0, 0, 2), "VERTICAL", DNODATA, 10, 10, connlen, connwidth)
     )
     # lake 2
     con_data.append(
-        (1, 0, (0, 0, 3), "VERTICAL", "None", 10, 10, connlen, connwidth)
+        (1, 0, (0, 0, 3), "VERTICAL", DNODATA, 10, 10, connlen, connwidth)
     )
     # lake 3
     con_data.append(
-        (2, 0, (0, 0, 4), "VERTICAL", "None", 10, 10, connlen, connwidth)
+        (2, 0, (0, 0, 4), "VERTICAL", DNODATA, 10, 10, connlen, connwidth)
     )
 
     p_data = [
@@ -332,14 +334,12 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # ensure lake concentrations were saved
-    name = sim.name
+    name = test.name
     gwtname = "gwt_" + name
     fname = gwtname + ".lkt.bin"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
 
     # load the lake concentrations and make sure all values are correct
@@ -350,7 +350,7 @@ def eval_results(sim):
 
     # load the aquifer concentrations and make sure all values are correct
     fname = gwtname + ".ucn"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     cobj = flopy.utils.HeadFile(fname, text="CONCENTRATION")
     caq = cobj.get_data()
     answer = np.zeros((7,))
@@ -358,7 +358,7 @@ def eval_results(sim):
 
     # load the lake budget file
     fname = gwtname + ".lkt.bud"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     bobj = flopy.utils.CellBudgetFile(fname, precision="double", verbose=False)
 
@@ -378,21 +378,14 @@ def eval_results(sim):
     for dtname, dttype in dt:
         assert np.allclose(res[dtname], answer[dtname]), f"{res} {answer}"
 
-    # uncomment when testing
-    # assert False
-
-
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=0
-        ),
-        ws,
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_lkt04.py b/autotest/test_gwt_lkt04.py
index f8bb2cf2c65..bc90cd82ab0 100644
--- a/autotest/test_gwt_lkt04.py
+++ b/autotest/test_gwt_lkt04.py
@@ -1,21 +1,23 @@
-# Simple one-layer model with a lak.  Purpose is to test a lake
-# with a variable stage and variable concentration.  The lake
-# starts at a concentration of 100. and slowly decreases as
-# fresh groundwater flows into it.  Concentrations in the aquifer
-# should remain at zero.
+"""
+Simple one-layer model with a lak.  Purpose is to test a lake
+with a variable stage and variable concentration.  The lake
+starts at a concentration of 100. and slowly decreases as
+fresh groundwater flows into it.  Concentrations in the aquifer
+should remain at zero.
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["lkt_04"]
+from framework import DNODATA, TestFramework
 
+cases = ["lkt_04"]
 
-def build_model(idx, dir, exe):
+
+def build_models(idx, test):
     lx = 5.0
     lz = 1.0
     nlay = 1
@@ -46,11 +48,11 @@ def build_model(idx, dir, exe):
     nouter, ninner = 700, 300
     hclose, rclose, relax = 1e-8, 1e-6, 0.97
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
     sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name=exe, sim_ws=dir
+        sim_name=name, version="mf6", exe_name="mf6", sim_ws=test.workspace
     )
     # create tdis package
     tdis = flopy.mf6.ModflowTdis(
@@ -127,20 +129,20 @@ def build_model(idx, dir, exe):
     )
 
     nlakeconn = 3  # note: this is the number of connectiosn for a lake, not total number of connections
-    # pak_data = [lakeno, strt, nlakeconn, CONC, dense, boundname]
+    # pak_data = [ifno, strt, nlakeconn, CONC, dense, boundname]
     pak_data = [(0, -0.4, nlakeconn, 0.0, 1025.0)]
 
     connlen = connwidth = delr / 2.0
     con_data = []
-    # con_data=(lakeno,iconn,(cellid),claktype,bedleak,belev,telev,connlen,connwidth )
+    # con_data=(ifno,iconn,(cellid),claktype,bedleak,belev,telev,connlen,connwidth )
     con_data.append(
-        (0, 0, (0, 0, 1), "HORIZONTAL", "None", 10, 10, connlen, connwidth)
+        (0, 0, (0, 0, 1), "HORIZONTAL", DNODATA, 10, 10, connlen, connwidth)
     )
     con_data.append(
-        (0, 1, (0, 0, 3), "HORIZONTAL", "None", 10, 10, connlen, connwidth)
+        (0, 1, (0, 0, 3), "HORIZONTAL", DNODATA, 10, 10, connlen, connwidth)
     )
     con_data.append(
-        (0, 2, (0, 0, 2), "VERTICAL", "None", 10, 10, connlen, connwidth)
+        (0, 2, (0, 0, 2), "VERTICAL", DNODATA, 10, 10, connlen, connwidth)
     )
     p_data = [
         (0, "STATUS", "ACTIVE"),
@@ -334,7 +336,7 @@ def build_model(idx, dir, exe):
 
 
 def get_mfsim(testsim):
-    ws = testsim.simpath
+    ws = testsim.workspace
     sim = flopy.mf6.MFSimulation.load(sim_ws=ws)
     return sim
 
@@ -371,17 +373,15 @@ def eval_csv_information(testsim):
     assert success, f"One or more errors encountered in budget checks"
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # eval csv files
-    eval_csv_information(sim)
+    eval_csv_information(test)
 
     # ensure lake concentrations were saved
-    name = sim.name
+    name = test.name
     gwtname = "gwt_" + name
     fname = gwtname + ".lkt.bin"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
 
     # load the lake concentrations and make sure all values are 100.
@@ -405,7 +405,7 @@ def eval_results(sim):
 
     # load the aquifer concentrations and make sure all values are correct
     fname = gwtname + ".ucn"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     cobj = flopy.utils.HeadFile(fname, text="CONCENTRATION")
     caq = cobj.get_alldata()
     answer = np.zeros(5)
@@ -414,7 +414,7 @@ def eval_results(sim):
     ), f"{caq[-1].flatten()} {answer}"
 
     # lkt observation results
-    fpth = os.path.join(sim.simpath, gwtname + ".lkt.obs.csv")
+    fpth = os.path.join(test.workspace, gwtname + ".lkt.obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -469,22 +469,14 @@ def eval_results(sim):
     answer = np.zeros(10)
     assert np.allclose(res, answer), f"{res} {answer}"
 
-    # uncomment when testing
-    # assert False
-
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    mf6 = targets["mf6"]
-    test = TestFramework()
-    test.build(lambda i, w: build_model(i, w, mf6), idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_moc3d01.py b/autotest/test_gwt_moc3d01.py
index f9a084e5160..27deccbff9e 100644
--- a/autotest/test_gwt_moc3d01.py
+++ b/autotest/test_gwt_moc3d01.py
@@ -3,10 +3,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = [
+cases = [
     "moc3d01a",
     "moc3d01b",
     "moc3d01c",
@@ -23,7 +23,7 @@
 decay = 7 * [None] + [0.01]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 122, 1
     nper = 1
     perlen = perlens[idx]  # [120.]
@@ -50,10 +50,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -271,13 +271,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -344,24 +342,20 @@ def eval_transport(sim):
     tsrescd = np.array(tsrescd)
 
     tsreslist = [tsresab, tsresab, tsrescd, tsrescd, None, None, None, None]
-    tsres = tsreslist[sim.idxsim]
+    tsres = tsreslist[idx]
     if tsres is not None:
         assert np.allclose(
             tsres, tssim
         ), "simulated concentrations do not match with known solution."
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_moc3d01_zod.py b/autotest/test_gwt_moc3d01_zod.py
index 1597ff67bc8..70d1733e87a 100644
--- a/autotest/test_gwt_moc3d01_zod.py
+++ b/autotest/test_gwt_moc3d01_zod.py
@@ -1,18 +1,20 @@
-# This autotest is based on the MOC3D problem 1 autotest except that it
-# tests the zero-order decay for a simple one-dimensional flow problem.
-# The test ensures that concentrations do not go below zero (they do go
-# slightly negative but, it does ensure that the decay rate shuts off
-# where concentrations are zero.
+"""
+This autotest is based on the MOC3D problem 1 autotest except that it
+tests the zero-order decay for a simple one-dimensional flow problem.
+The test ensures that concentrations do not go below zero (they do go
+slightly negative but, it does ensure that the decay rate shuts off
+where concentrations are zero.
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = [
+cases = [
     "moc3d01zoda",
     "moc3d01zodb",
     "moc3d01zodc",
@@ -23,7 +25,7 @@
 ist_package = [False, False, True, True]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 122, 1
     nper = 1
     perlen = [120]
@@ -51,10 +53,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name,
         version="mf6",
@@ -214,15 +216,15 @@ def build_model(idx, dir):
     )
 
     # storage
-    theta_mobile = 0.1 # vol mobile voids per cell volume
-    volfrac_immobile = 0.
-    theta_immobile = 0.
+    theta_mobile = 0.1  # vol mobile voids per cell volume
+    volfrac_immobile = 0.0
+    theta_immobile = 0.0
     if ist_package[idx]:
         # if dual domain, then assume half of cell is mobile and other half is immobile
         volfrac_immobile = 0.5
         theta_immobile = theta_mobile
         porosity_immobile = theta_immobile / volfrac_immobile
-    volfrac_mobile = 1. - volfrac_immobile
+    volfrac_mobile = 1.0 - volfrac_immobile
     porosity_mobile = theta_mobile / volfrac_mobile
 
     rtd = retardation[idx]
@@ -362,14 +364,12 @@ def make_plot_cd(cobj, fname=None):
     return
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
 
     # get mobile domain concentration object
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -382,15 +382,15 @@ def eval_transport(sim):
     makeplot = False
     if makeplot:
         fname = "fig-ct.pdf"
-        fname = os.path.join(sim.simpath, fname)
+        fname = os.path.join(test.workspace, fname)
         make_plot_ct(tssim, fname)
 
         fname = "fig-cd.pdf"
-        fname = os.path.join(sim.simpath, fname)
+        fname = os.path.join(test.workspace, fname)
         make_plot_cd(cobj, fname)
 
     # get mobile domain budget object
-    fpth = os.path.join(sim.simpath, f"{gwtname}.cbc")
+    fpth = os.path.join(test.workspace, f"{gwtname}.cbc")
     bobj = flopy.utils.CellBudgetFile(fpth, precision="double")
 
     # Check to make sure decay rates in budget file are correct.  If there is
@@ -402,7 +402,7 @@ def eval_transport(sim):
     delt = 0.5
     vcell = 0.1 * 0.1 * 1.0
     porosity = 0.1
-    decay_rate = decay[sim.idxsim]
+    decay_rate = decay[idx]
     for i in range(122):
         if conc[i] / delt > decay_rate:
             qknown = -decay_rate * vcell * porosity
@@ -414,7 +414,7 @@ def eval_transport(sim):
         # print(i, qdecay_budfile[i], conc[i])
 
     # get immobile domain concentration object
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ist.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ist.ucn")
     cimobj = None
     if os.path.isfile(fpth):
         try:
@@ -560,7 +560,7 @@ def eval_transport(sim):
     tsresc = np.array(tsresc)
     tsresd = np.array(tsresd)
     tsreslist = [tsresa, tsresb, tsresc, tsresd]
-    tsres = tsreslist[sim.idxsim]
+    tsres = tsreslist[idx]
     errmsg = (
         "Simulated concentrations do not match with known solution.\n"
         "{} /= {}".format(tssim, tsres)
@@ -569,17 +569,13 @@ def eval_transport(sim):
         assert np.allclose(tsres, tssim), errmsg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_moc3d02.py b/autotest/test_gwt_moc3d02.py
index 4d2b476c3dc..729cdcba760 100644
--- a/autotest/test_gwt_moc3d02.py
+++ b/autotest/test_gwt_moc3d02.py
@@ -3,14 +3,14 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["moc3d02a", "moc3d02b"]
+cases = ["moc3d02a", "moc3d02b"]
 xt3d = [None, True]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 40, 12, 30
     nper = 1
     perlen = [400]
@@ -42,10 +42,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -240,13 +240,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -310,17 +308,13 @@ def eval_transport(sim):
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_moc3d03.py b/autotest/test_gwt_moc3d03.py
index f236107ad1d..cedfebfdf8e 100644
--- a/autotest/test_gwt_moc3d03.py
+++ b/autotest/test_gwt_moc3d03.py
@@ -3,13 +3,13 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["moc3d03"]
+cases = ["moc3d03"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 30, 30
     nper = 1
     perlen = [1000]
@@ -41,10 +41,10 @@ def build_model(idx, dir):
     for id in range(nper):
         tdis_rc.append((perlen[id], nstp[id], tsmult[id]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -234,13 +234,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -292,17 +290,13 @@ def eval_transport(sim):
 
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_mst01.py b/autotest/test_gwt_mst01.py
index d1f53e59118..2eadf4b2036 100644
--- a/autotest/test_gwt_mst01.py
+++ b/autotest/test_gwt_mst01.py
@@ -3,18 +3,17 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["mst01"]
+cases = ["mst01"]
 laytyp = [1]
 ss = [0.0]
 sy = [0.1]
 nlay, nrow, ncol = 4, 1, 1
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     nper = 1
     perlen = [3.0]
     nstp = [3]
@@ -35,10 +34,10 @@ def build_model(idx, dir):
     for id in range(nper):
         tdis_rc.append((perlen[id], nstp[id], tsmult[id]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -216,13 +215,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     cobj = flopy.utils.HeadFile(fpth, precision="double", text="CONCENTRATION")
     conc1 = cobj.get_data(totim=3.0)
 
@@ -233,17 +230,13 @@ def eval_transport(sim):
     )
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_mst02.py b/autotest/test_gwt_mst02.py
index 18a2a1e33b6..8a7ee63d18c 100644
--- a/autotest/test_gwt_mst02.py
+++ b/autotest/test_gwt_mst02.py
@@ -1,16 +1,16 @@
 """
 Test the GWT Sorption (RCT) Package by running a ...
-
 """
+
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["mst02a", "mst02b"]
+cases = ["mst02a", "mst02b"]
 distcoef = [0.0, 1.0]
 nlay, nrow, ncol = 1, 1, 2
 
@@ -46,8 +46,7 @@
 tsanswers = [ts1, ts2]
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     nper = 1
     perlen = [1.0]
     nstp = [10]
@@ -71,10 +70,10 @@ def build_model(idx, dir):
     for id in range(nper):
         tdis_rc.append((perlen[id], nstp[id], tsmult[id]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -227,14 +226,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    idx = sim.idxsim
-    name = ex[idx]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -249,7 +245,7 @@ def eval_transport(sim):
     )
 
     # Check budget file
-    fpth = os.path.join(sim.simpath, f"{gwtname}.bud")
+    fpth = os.path.join(test.workspace, f"{gwtname}.bud")
     try:
         bobj = flopy.utils.CellBudgetFile(fpth, precision="double")
         ra = bobj.get_data(totim=1.0)
@@ -257,17 +253,13 @@ def eval_transport(sim):
         assert False, f'could not load data from "{fpth}"'
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_mst03.py b/autotest/test_gwt_mst03.py
index 036cfa4f296..20c90911186 100644
--- a/autotest/test_gwt_mst03.py
+++ b/autotest/test_gwt_mst03.py
@@ -2,7 +2,6 @@
 Test the MST Package and its ability to calculate simple mixing for a one-cell
 model.  Patterned after the simple test presented in the MT3D-USGS manual on
 pages 9-10.
-
 """
 
 import os
@@ -10,18 +9,17 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["mst03"]
+cases = ["mst03"]
 laytyp = [1]
 ss = [1.0e-10]
 sy = [0.1]
 nlay, nrow, ncol = 1, 1, 1
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     nper = 2
     perlen = [2.0, 2.0]
     nstp = [14, 14]
@@ -40,10 +38,10 @@ def build_model(idx, dir):
     for id in range(nper):
         tdis_rc.append((perlen[id], nstp[id], tsmult[id]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -215,18 +213,16 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwtname = "gwt_" + name
     gwfname = "gwf_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwfname}.hds")
+    fpth = os.path.join(test.workspace, f"{gwfname}.hds")
     hobj = flopy.utils.HeadFile(fpth, precision="double")
     head = hobj.get_alldata().flatten()
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     cobj = flopy.utils.HeadFile(fpth, precision="double", text="CONCENTRATION")
     conc = cobj.get_alldata().flatten()
 
@@ -285,17 +281,13 @@ def eval_transport(sim):
     assert np.allclose(conc, canswer, atol=1.0e-8), errmsg
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_mst04_noadv.py b/autotest/test_gwt_mst04_noadv.py
index 14d711d7b16..9e438805627 100644
--- a/autotest/test_gwt_mst04_noadv.py
+++ b/autotest/test_gwt_mst04_noadv.py
@@ -1,21 +1,19 @@
 """
-MODFLOW 6 Autotest
 Test zero-order decay by running a one-cell model with ten 1-day time steps
 with a decay rate of -1.  Result should be 10 at the end.
-
 """
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["mst04_noadv"]
+cases = ["mst04_noadv"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 1
     nper = 1
     perlen = [10.0]
@@ -33,10 +31,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -109,13 +107,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     cobj = flopy.utils.HeadFile(fpth, precision="double", text="CONCENTRATION")
     conc = cobj.get_data()
 
@@ -125,17 +121,13 @@ def eval_transport(sim):
     assert np.allclose(cres, conc.flatten()), msg
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_mst05.py b/autotest/test_gwt_mst05.py
index c305d3ff3f7..dba4a1975b7 100644
--- a/autotest/test_gwt_mst05.py
+++ b/autotest/test_gwt_mst05.py
@@ -1,7 +1,5 @@
 """
-MODFLOW 6 Autotest
 Test isotherms.
-
 """
 
 import os
@@ -11,10 +9,10 @@
 import pytest
 from flopy.utils.binaryfile import write_budget, write_head
 from flopy.utils.gridutil import uniform_flow_field
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["mst05a", "mst05b"]
+cases = ["mst05a", "mst05b"]
 isotherm = ["freundlich", "langmuir"]
 distcoef = [0.3, 100.0]
 sp2 = [0.7, 0.003]
@@ -22,7 +20,7 @@
 ymax_plot = [0.5, 1.0]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 101
     perlen = [160.0, 1340.0]
     nper = len(perlen)
@@ -48,10 +46,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -267,13 +265,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = ex[sim.idxsim]
+def check_output(idx, test):
+    name = cases[idx]
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     try:
         cobj = flopy.utils.HeadFile(
             fpth, precision="double", text="CONCENTRATION"
@@ -282,7 +278,7 @@ def eval_transport(sim):
     except:
         assert False, f'could not load data from "{fpth}"'
 
-    fpth = os.path.join(sim.simpath, "conc_obs.csv")
+    fpth = os.path.join(test.workspace, "conc_obs.csv")
     try:
         obs = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -290,8 +286,8 @@ def eval_transport(sim):
 
     cnorm = obs["X008"] / 0.05
     cnorm_max = [0.32842034, 0.875391418]
-    msg = f"{cnorm_max[sim.idxsim]} /= {cnorm.max()}"
-    assert np.allclose(cnorm_max[sim.idxsim], cnorm.max(), atol=0.001), msg
+    msg = f"{cnorm_max[idx]} /= {cnorm.max()}"
+    assert np.allclose(cnorm_max[idx], cnorm.max(), atol=0.001), msg
 
     savefig = False
     if savefig:
@@ -299,26 +295,22 @@ def eval_transport(sim):
 
         fig = plt.figure()
         plt.plot(obs["time"], obs["X008"] / 0.05, "bo-")
-        plt.xlim(0, xmax_plot[sim.idxsim])
-        plt.ylim(0, ymax_plot[sim.idxsim])
+        plt.xlim(0, xmax_plot[idx])
+        plt.ylim(0, ymax_plot[idx])
         plt.xlabel("Time, in seconds")
         plt.ylabel("Normalized Concentration")
-        plt.title(isotherm[sim.idxsim])
-        fname = os.path.join(sim.simpath, "results.png")
+        plt.title(isotherm[idx])
+        fname = os.path.join(test.workspace, "results.png")
         plt.savefig(fname)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_mst06_noadv.py b/autotest/test_gwt_mst06_noadv.py
index 95dcc8882e2..b2fef2ad877 100644
--- a/autotest/test_gwt_mst06_noadv.py
+++ b/autotest/test_gwt_mst06_noadv.py
@@ -1,22 +1,20 @@
 """
-MODFLOW 6 Autotest
 Test zero-order decay by running a one-cell model with ten 1-day time steps
 with a decay rate of 1.  And a starting concentration of 8.  Result should be
 0 at the end and decay should shot off once concentration is zero.
-
 """
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["mst06_noadv"]
+cases = ["mst06_noadv"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 1
     nper = 1
     perlen = [10.0]
@@ -34,10 +32,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -119,13 +117,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     cobj = flopy.utils.HeadFile(fpth, precision="double", text="CONCENTRATION")
     conc = cobj.get_ts((0, 0, 0))
 
@@ -139,7 +135,7 @@ def eval_transport(sim):
     assert np.allclose(cres, conc[:, 1]), msg
 
     # Check budget file
-    fpth = os.path.join(sim.simpath, f"{gwtname}.bud")
+    fpth = os.path.join(test.workspace, f"{gwtname}.bud")
     try:
         bobj = flopy.utils.CellBudgetFile(fpth, precision="double")
     except:
@@ -165,17 +161,13 @@ def eval_transport(sim):
     assert np.allclose(decay_rate, decay_rate_answer), msg
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_mt3dms_p01.py b/autotest/test_gwt_mt3dms_p01.py
index bd163a76202..3b19a6c1f44 100644
--- a/autotest/test_gwt_mt3dms_p01.py
+++ b/autotest/test_gwt_mt3dms_p01.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 Test to compare MODFLOW 6 groundwater transport simulation results to MT3DMS
 results.  This test was first documented in Zheng and Wang (1999) (MT3DMS:
 A Modular Three-Dimensional Multispecies Transport Model for Simulation of
@@ -20,9 +19,14 @@
 """
 
 import os
+from pathlib import Path
+from typing import Tuple
 
 import flopy
 import numpy as np
+import pytest
+
+from conftest import try_get_target
 
 testgroup = "mt3dms_p01"
 
@@ -383,7 +387,6 @@ def p01mf6(
         theta_immobile = prsity2
         porosity_immobile = theta_immobile / volfrac_immobile
         porosity_mobile = prsity / volfrac_mobile
-        
 
     first_order_decay = True
     if zero_order_decay:
@@ -470,6 +473,14 @@ def p01mf6(
     return sim, conc
 
 
+def get_binaries(targets) -> Tuple[Path, Path, Path]:
+    return (
+        targets["mf6"],
+        try_get_target(targets, "mf2005s"),
+        try_get_target(targets, "mt3dms"),
+    )
+
+
 def test_mt3dmsp01a(function_tmpdir, targets):
     longitudinal_dispersivity = 0.0
     retardation = 1.0
@@ -478,8 +489,10 @@ def test_mt3dmsp01a(function_tmpdir, targets):
     zeta = None
     prsity2 = None
 
-    mf6 = targets["mf6"]
-    mf6_ws = str(function_tmpdir / (testgroup + "a"))
+    mf6, mf2005, mt3dms = get_binaries(targets)
+    mf6_ws = function_tmpdir / f"{testgroup}a"
+    mt3d_ws = mf6_ws / "mt3d"
+
     sim, conc_mf6 = p01mf6(
         mf6_ws,
         longitudinal_dispersivity,
@@ -491,9 +504,6 @@ def test_mt3dmsp01a(function_tmpdir, targets):
         exe=mf6,
     )
 
-    mf2005 = targets["mf2005s"]
-    mt3dms = targets["mt3dms"]
-    mt3d_ws = os.path.join(mf6_ws, "mt3d")
     mf, mt, conc_mt3d, cvt, mvt = p01mt3d(
         mt3d_ws,
         longitudinal_dispersivity,
@@ -506,8 +516,9 @@ def test_mt3dmsp01a(function_tmpdir, targets):
         mt3dms=mt3dms,
     )
 
-    msg = f"concentrations not equal {conc_mt3d} {conc_mf6}"
-    assert np.allclose(conc_mt3d, conc_mf6, atol=1e-4), msg
+    assert np.allclose(
+        conc_mt3d, conc_mf6, atol=1e-4
+    ), f"concentrations not equal {conc_mt3d} {conc_mf6}"
 
     # load transport budget
     # budget text:
@@ -543,8 +554,10 @@ def test_mt3dmsp01b(function_tmpdir, targets):
     zeta = None
     prsity2 = None
 
-    mf6 = targets["mf6"]
-    mf6_ws = str(function_tmpdir / (testgroup + "b"))
+    mf6, mf2005, mt3dms = get_binaries(targets)
+    mf6_ws = function_tmpdir / f"{testgroup}b"
+    mt3d_ws = mf6_ws / "mt3d"
+
     sim, conc_mf6 = p01mf6(
         mf6_ws,
         longitudinal_dispersivity,
@@ -556,9 +569,6 @@ def test_mt3dmsp01b(function_tmpdir, targets):
         exe=mf6,
     )
 
-    mf2005 = targets["mf2005s"]
-    mt3dms = targets["mt3dms"]
-    mt3d_ws = os.path.join(mf6_ws, "mt3d")
     mf, mt, conc_mt3d, cvt, mvt = p01mt3d(
         mt3d_ws,
         longitudinal_dispersivity,
@@ -571,8 +581,9 @@ def test_mt3dmsp01b(function_tmpdir, targets):
         mt3dms=mt3dms,
     )
 
-    msg = f"concentrations not equal {conc_mt3d} {conc_mf6}"
-    assert np.allclose(conc_mt3d, conc_mf6, atol=1e-4), msg
+    assert np.allclose(
+        conc_mt3d, conc_mf6, atol=1e-4
+    ), f"concentrations not equal {conc_mt3d} {conc_mf6}"
 
 
 def test_mt3dmsp01c(function_tmpdir, targets):
@@ -583,8 +594,10 @@ def test_mt3dmsp01c(function_tmpdir, targets):
     zeta = None
     prsity2 = None
 
-    mf6 = targets["mf6"]
-    mf6_ws = str(function_tmpdir / (testgroup + "c"))
+    mf6, mf2005, mt3dms = get_binaries(targets)
+    mf6_ws = function_tmpdir / f"{testgroup}c"
+    mt3d_ws = mf6_ws / "mt3d"
+
     sim, conc_mf6 = p01mf6(
         mf6_ws,
         longitudinal_dispersivity,
@@ -596,9 +609,6 @@ def test_mt3dmsp01c(function_tmpdir, targets):
         exe=mf6,
     )
 
-    mf2005 = targets["mf2005s"]
-    mt3dms = targets["mt3dms"]
-    mt3d_ws = os.path.join(mf6_ws, "mt3d")
     mf, mt, conc_mt3d, cvt, mvt = p01mt3d(
         mt3d_ws,
         longitudinal_dispersivity,
@@ -611,8 +621,9 @@ def test_mt3dmsp01c(function_tmpdir, targets):
         mt3dms=mt3dms,
     )
 
-    msg = f"concentrations not equal {conc_mt3d} {conc_mf6}"
-    assert np.allclose(conc_mt3d, conc_mf6, atol=1e-4), msg
+    assert np.allclose(
+        conc_mt3d, conc_mf6, atol=1e-4
+    ), f"concentrations not equal {conc_mt3d} {conc_mf6}"
 
 
 def test_mt3dmsp01d(function_tmpdir, targets):
@@ -623,8 +634,10 @@ def test_mt3dmsp01d(function_tmpdir, targets):
     zeta = None
     prsity2 = None
 
-    mf6 = targets["mf6"]
-    mf6_ws = str(function_tmpdir / (testgroup + "d"))
+    mf6, mf2005, mt3dms = get_binaries(targets)
+    mf6_ws = function_tmpdir / f"{testgroup}d"
+    mt3d_ws = mf6_ws / "mt3d"
+
     sim, conc_mf6 = p01mf6(
         mf6_ws,
         longitudinal_dispersivity,
@@ -636,9 +649,6 @@ def test_mt3dmsp01d(function_tmpdir, targets):
         exe=mf6,
     )
 
-    mf2005 = targets["mf2005s"]
-    mt3dms = targets["mt3dms"]
-    mt3d_ws = os.path.join(mf6_ws, "mt3d")
     mf, mt, conc_mt3d, cvt, mvt = p01mt3d(
         mt3d_ws,
         longitudinal_dispersivity,
@@ -651,8 +661,9 @@ def test_mt3dmsp01d(function_tmpdir, targets):
         mt3dms=mt3dms,
     )
 
-    msg = f"concentrations not equal {conc_mt3d} {conc_mf6}"
-    assert np.allclose(conc_mt3d, conc_mf6, atol=1e-4), msg
+    assert np.allclose(
+        conc_mt3d, conc_mf6, atol=1e-4
+    ), f"concentrations not equal {conc_mt3d} {conc_mf6}"
 
 
 def test_mt3dmsp01e(function_tmpdir, targets):
@@ -663,8 +674,10 @@ def test_mt3dmsp01e(function_tmpdir, targets):
     zeta = 0.1
     prsity2 = 0.05
 
-    mf6 = targets["mf6"]
-    mf6_ws = str(function_tmpdir / (testgroup + "e"))
+    mf6, mf2005, mt3dms = get_binaries(targets)
+    mf6_ws = function_tmpdir / f"{testgroup}e"
+    mt3d_ws = mf6_ws / "mt3d"
+
     sim, conc_mf6 = p01mf6(
         mf6_ws,
         longitudinal_dispersivity,
@@ -676,9 +689,6 @@ def test_mt3dmsp01e(function_tmpdir, targets):
         exe=mf6,
     )
 
-    mf2005 = targets["mf2005s"]
-    mt3dms = targets["mt3dms"]
-    mt3d_ws = os.path.join(mf6_ws, "mt3d")
     mf, mt, conc_mt3d, cvt, mvt = p01mt3d(
         mt3d_ws,
         longitudinal_dispersivity,
@@ -691,8 +701,9 @@ def test_mt3dmsp01e(function_tmpdir, targets):
         mt3dms=mt3dms,
     )
 
-    msg = f"concentrations not equal {conc_mt3d} {conc_mf6}"
-    assert np.allclose(conc_mt3d, conc_mf6, atol=1e-1), msg
+    assert np.allclose(
+        conc_mt3d, conc_mf6, atol=1e-1
+    ), f"concentrations not equal {conc_mt3d} {conc_mf6}"
 
 
 def test_mt3dmsp01f(function_tmpdir, targets):
@@ -703,8 +714,10 @@ def test_mt3dmsp01f(function_tmpdir, targets):
     zeta = 0.1
     prsity2 = 0.05
 
-    mf6 = targets["mf6"]
-    mf6_ws = str(function_tmpdir / (testgroup + "f"))
+    mf6, mf2005, mt3dms = get_binaries(targets)
+    mf6_ws = function_tmpdir / f"{testgroup}f"
+    mt3d_ws = mf6_ws / "mt3d"
+
     sim, conc_mf6 = p01mf6(
         mf6_ws,
         longitudinal_dispersivity,
@@ -717,9 +730,6 @@ def test_mt3dmsp01f(function_tmpdir, targets):
         exe=mf6,
     )
 
-    mf2005 = targets["mf2005s"]
-    mt3dms = targets["mt3dms"]
-    mt3d_ws = os.path.join(mf6_ws, "mt3d")
     mf, mt, conc_mt3d, cvt, mvt = p01mt3d(
         mt3d_ws,
         longitudinal_dispersivity,
@@ -732,8 +742,9 @@ def test_mt3dmsp01f(function_tmpdir, targets):
         mt3dms=mt3dms,
     )
 
-    msg = f"concentrations not equal {conc_mt3d} {conc_mf6}"
-    assert np.allclose(conc_mt3d, conc_mf6, atol=1e-1), msg
+    assert np.allclose(
+        conc_mt3d, conc_mf6, atol=1e-1
+    ), f"concentrations not equal {conc_mt3d} {conc_mf6}"
 
 
 def test_mt3dmsp01g(function_tmpdir, targets):
@@ -744,8 +755,10 @@ def test_mt3dmsp01g(function_tmpdir, targets):
     zeta = None
     prsity2 = None
 
-    mf6 = targets["mf6"]
-    mf6_ws = str(function_tmpdir / (testgroup + "g"))
+    mf6, mf2005, mt3dms = get_binaries(targets)
+    mf6_ws = function_tmpdir / f"{testgroup}g"
+    mt3d_ws = mf6_ws / "mt3d"
+
     sim, conc_mf6 = p01mf6(
         mf6_ws,
         longitudinal_dispersivity,
@@ -758,9 +771,6 @@ def test_mt3dmsp01g(function_tmpdir, targets):
         exe=mf6,
     )
 
-    mf2005 = targets["mf2005s"]
-    mt3dms = targets["mt3dms"]
-    mt3d_ws = os.path.join(mf6_ws, "mt3d")
     mf, mt, conc_mt3d, cvt, mvt = p01mt3d(
         mt3d_ws,
         longitudinal_dispersivity,
@@ -775,5 +785,6 @@ def test_mt3dmsp01g(function_tmpdir, targets):
         mt3dms=mt3dms,
     )
 
-    msg = f"concentrations not equal {conc_mt3d} {conc_mf6}"
-    assert np.allclose(conc_mt3d, conc_mf6, atol=1.0e-4), msg
+    assert np.allclose(
+        conc_mt3d, conc_mf6, atol=1.0e-4
+    ), f"concentrations not equal {conc_mt3d} {conc_mf6}"
diff --git a/autotest/test_gwt_mvt01.py b/autotest/test_gwt_mvt01.py
index 1818b8f5724..a38091b9063 100644
--- a/autotest/test_gwt_mvt01.py
+++ b/autotest/test_gwt_mvt01.py
@@ -1,21 +1,23 @@
-# Simple one-layer model with a lak and sfr network on top.  Purpose is to
-# test movement of solute between advanced packages.  In this case water
-# from a lake outlet is moved into the first sfr reach.  The test confirms
-# that the solute from the lake is moved into the sfr reach.
-# There is no flow between the stream and the aquifer.
+"""
+Simple one-layer model with a lak and sfr network on top.  Purpose is to
+test movement of solute between advanced packages.  In this case water
+from a lake outlet is moved into the first sfr reach.  The test confirms
+that the solute from the lake is moved into the sfr reach.
+There is no flow between the stream and the aquifer.
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["mvt_01"]
+cases = ["mvt_01"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     lx = 7.0
     lz = 1.0
     nlay = 1
@@ -46,10 +48,10 @@ def build_model(idx, dir):
     nouter, ninner = 700, 300
     hclose, rclose, relax = 1e-8, 1e-6, 0.97
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -142,7 +144,7 @@ def build_model(idx, dir):
     )
 
     nlakeconn = 1  # note: this is the number of connectiosn for a lake, not total number of connections
-    # pak_data = [lakeno, strt, nlakeconn, CONC, dense, boundname]
+    # pak_data = [ifno, strt, nlakeconn, CONC, dense, boundname]
     pak_data = [
         (0, 1.0, nlakeconn, 0.0, 1025.0),
         (1, 1.0, nlakeconn, 0.0, 1025.0),
@@ -150,7 +152,7 @@ def build_model(idx, dir):
 
     connlen = connwidth = delr / 2.0
     con_data = []
-    # con_data=(lakeno,iconn,(cellid),claktype,bedleak,belev,telev,connlen,connwidth )
+    # con_data=(ifno,iconn,(cellid),claktype,bedleak,belev,telev,connlen,connwidth )
     con_data.append(
         (0, 0, (0, 0, 0), "VERTICAL", 0.0, 0, 0, connlen, connwidth)
     )
@@ -481,14 +483,12 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # ensure lake concentrations were saved
-    name = sim.name
+    name = test.name
     gwtname = "gwt_" + name
     fname = gwtname + ".sft.bin"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
 
     # load the lake concentrations and make sure all values are correct
@@ -497,14 +497,14 @@ def eval_results(sim):
 
     # load the aquifer concentrations and make sure all values are correct
     fname = gwtname + ".ucn"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     cobj = flopy.utils.HeadFile(fname, text="CONCENTRATION")
     caq = cobj.get_data().flatten()
 
     assert np.allclose(csft, caq), f"{csft} {caq}"
 
     # sft observation results
-    fpth = os.path.join(sim.simpath, gwtname + ".sft.obs.csv")
+    fpth = os.path.join(test.workspace, gwtname + ".sft.obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -518,7 +518,7 @@ def eval_results(sim):
 
     # load the sft budget file
     fname = gwtname + ".sft.bud"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     bobj = flopy.utils.CellBudgetFile(fname, precision="double", verbose=False)
     # check the flow-ja-face terms
@@ -532,7 +532,7 @@ def eval_results(sim):
     # get mvt results from listing file
     bud_lst = ["SFR-1_IN", "SFR-1_OUT", "LAK-1_IN", "LAK-1_OUT"]
     fname = gwtname + ".lst"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     budl = flopy.utils.Mf6ListBudget(
         fname, budgetkey="TRANSPORT MOVER BUDGET FOR ENTIRE MODEL"
     )
@@ -543,21 +543,14 @@ def eval_results(sim):
     )
     assert np.allclose(d0["SFR-1_OUT"], d0["LAK-1_IN"])
 
-    # uncomment when testing so files aren't deleted
-    # assert False
-
-
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=0
-        ),
-        ws,
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_mvt02.py b/autotest/test_gwt_mvt02.py
index 20dfa5e4762..cc49f432d35 100644
--- a/autotest/test_gwt_mvt02.py
+++ b/autotest/test_gwt_mvt02.py
@@ -1,21 +1,23 @@
-# Simple one-layer model with a drn and sfr network on top.  Purpose is to
-# test movement of solute between stress and advanced packages.  In this case
-# water from a drain is moved into the first sfr reach.  The test confirms
-# that the solute from the drain is moved into the sfr reach.
-# There is no flow between the stream and the aquifer.
+"""
+Simple one-layer model with a drn and sfr network on top.  Purpose is to
+test movement of solute between stress and advanced packages.  In this case
+water from a drain is moved into the first sfr reach.  The test confirms
+that the solute from the drain is moved into the sfr reach.
+There is no flow between the stream and the aquifer.
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["mvt_02"]
+cases = ["mvt_02"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     lx = 7.0
     lz = 1.0
     nlay = 1
@@ -44,10 +46,10 @@ def build_model(idx, dir):
     nouter, ninner = 20, 10
     hclose, rclose, relax = 1e-8, 1e-6, 0.97
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name,
         version="mf6",
@@ -245,7 +247,6 @@ def build_model(idx, dir):
 
     transport = True
     if transport:
-
         # create gwt model
         gwtname = "gwt_" + name
         gwt = flopy.mf6.MFModel(
@@ -384,14 +385,13 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwtname = "gwt_" + name
 
     # Load csv budget and make sure names are correct
     fname = f"{gwtname}.bud.csv"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     budcsv = np.genfromtxt(fname, names=True, delimiter=",", deletechars="")
     answer = [
         "time",
@@ -414,19 +414,19 @@ def eval_results(sim):
 
     # ensure sfr concentrations were saved
     fname = gwtname + ".sft.bin"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     cobj = flopy.utils.HeadFile(fname, text="CONCENTRATION")
     csft = cobj.get_data().flatten()
 
     # load the aquifer concentrations
     fname = gwtname + ".ucn"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     cobj = flopy.utils.HeadFile(fname, text="CONCENTRATION")
     caq = cobj.get_data().flatten()
 
     # sft observation results
-    fpth = os.path.join(sim.simpath, gwtname + ".sft.obs.csv")
+    fpth = os.path.join(test.workspace, gwtname + ".sft.obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -457,13 +457,13 @@ def eval_results(sim):
 
     # load the mvt budget file
     fname = gwtname + ".mvt.bud"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     mobj = flopy.utils.CellBudgetFile(fname, precision="double", verbose=False)
 
     # load the sft budget file
     fname = gwtname + ".sft.bud"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     bobj = flopy.utils.CellBudgetFile(fname, precision="double", verbose=False)
     # check the flow-ja-face terms
@@ -474,21 +474,14 @@ def eval_results(sim):
     res = bobj.get_data(text="storage")[-1]
     # print(res)
 
-    # uncomment when testing so files aren't deleted
-    # assert False
-
-
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=0
-        ),
-        ws,
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_mvt02fmi.py b/autotest/test_gwt_mvt02fmi.py
index 702b9a80697..4ed60955133 100644
--- a/autotest/test_gwt_mvt02fmi.py
+++ b/autotest/test_gwt_mvt02fmi.py
@@ -1,8 +1,10 @@
-# Simple one-layer model with a drn and sfr network on top.  Purpose is to
-# test movement of solute between stress and advanced packages.  In this case
-# water from a drain is moved into the first sfr reach.  The test confirms
-# that the solute from the drain is moved into the sfr reach.
-# There is no flow between the stream and the aquifer.
+"""
+Simple one-layer model with a drn and sfr network on top.  Purpose is to
+test movement of solute between stress and advanced packages.  In this case
+water from a drain is moved into the first sfr reach.  The test confirms
+that the solute from the drain is moved into the sfr reach.
+There is no flow between the stream and the aquifer.
+"""
 
 import os
 from os.path import join
@@ -11,7 +13,7 @@
 import numpy as np
 
 testgroup = "mvt02fmi"
-ex = ["mvt02fmi"]
+cases = ["mvt02fmi"]
 
 # parameters
 lx = 7.0
@@ -390,8 +392,6 @@ def run_transport_model(dir, exe):
     errmsg = f"transport model did not terminate successfully\n{buff}"
     assert success, errmsg
 
-    print("evaluating results...")
-
     # Load csv budget and make sure names are correct
     fname = f"{gwtname}.bud.csv"
     fname = os.path.join(gwt.model_ws, fname)
@@ -470,6 +470,5 @@ def run_transport_model(dir, exe):
 
 
 def test_mvt02fmi(function_tmpdir, targets):
-    mf6 = targets.mf6
-    run_flow_model(str(function_tmpdir), mf6)
-    run_transport_model(str(function_tmpdir), mf6)
+    run_flow_model(str(function_tmpdir), targets["mf6"])
+    run_transport_model(str(function_tmpdir), targets["mf6"])
diff --git a/autotest/test_gwt_mwt01.py b/autotest/test_gwt_mwt01.py
index bf70531e86f..d637b1fa631 100644
--- a/autotest/test_gwt_mwt01.py
+++ b/autotest/test_gwt_mwt01.py
@@ -1,20 +1,22 @@
-# Simple 3-layer model with a maw.  Purpose is to test pumping
-# with concentration being drawn in from edge.  The aquifer
-# starts with a concentration of zero, but the values grow as the boundary
-# flows into the aquifer.
+"""
+Simple 3-layer model with a maw.  Purpose is to test pumping
+with concentration being drawn in from edge.  The aquifer
+starts with a concentration of zero, but the values grow as the boundary
+flows into the aquifer.
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["mwt_01"]
+cases = ["mwt_01"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     lx = 5.0
     lz = 3.0
     nlay = 3
@@ -44,10 +46,10 @@ def build_model(idx, dir):
     nouter, ninner = 700, 300
     hclose, rclose, relax = 1e-8, 1e-6, 0.97
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -309,7 +311,7 @@ def build_model(idx, dir):
 def check_obs(sim):
     print("checking obs...")
     name = sim.name
-    ws = sim.simpath
+    ws = sim.workspace
     sim = flopy.mf6.MFSimulation.load(sim_ws=ws)
     gwfname = "gwf_" + name
     gwtname = "gwt_" + name
@@ -375,35 +377,29 @@ def check_obs(sim):
     assert success, "One or more MWT obs checks did not pass"
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # ensure mwt concentrations were saved
-    name = sim.name
+    name = test.name
     gwtname = "gwt_" + name
     fname = gwtname + ".mwt.bin"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
 
     # ensure gwt concentrations were saved
     fname = gwtname + ".ucn"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
 
-    check_obs(sim)
+    check_obs(test)
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_mwt02.py b/autotest/test_gwt_mwt02.py
index 37129a329a1..db886b0ca0a 100644
--- a/autotest/test_gwt_mwt02.py
+++ b/autotest/test_gwt_mwt02.py
@@ -1,18 +1,17 @@
-# This is the reinjection problem described in the MT3D supplementary
-# information.
+"""This is the reinjection problem described in the MT3D supplementary information."""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["mwt_02"]
+cases = ["mwt_02"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay = 1
     nrow = 31
     ncol = 46
@@ -38,10 +37,10 @@ def build_model(idx, dir):
     nouter, ninner = 700, 300
     hclose, rclose, relax = 1e-8, 1e-6, 0.97
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -121,7 +120,7 @@ def build_model(idx, dir):
 
     # MAW
     opth = f"{name}.maw.obs"
-    # <wellno> <radius> <bottom> <strt> <condeqn> <ngwfnodes> [<aux(naux)>] [<boundname>]
+    # <ifno> <radius> <bottom> <strt> <condeqn> <ngwfnodes> [<aux(naux)>] [<boundname>]
     wellbottom = 0.0
     wellradius = 0.1
     ngwfnodes = 1
@@ -130,7 +129,7 @@ def build_model(idx, dir):
         [iwell, wellradius, wellbottom, strt, "THIEM", ngwfnodes, concwell]
         for iwell in range(4)
     ]
-    # <wellno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
+    # <ifno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
     wellconnectionsrecarray = [
         [0, 0, (0, 15, 15), 10.0, 0.0, 10.0, 0.1],
         [1, 0, (0, 15, 20), 10.0, 0.0, 10.0, 0.1],
@@ -395,7 +394,7 @@ def build_model(idx, dir):
 def make_plot(sim):
     print("making plots...")
     name = sim.name
-    ws = sim.simpath
+    ws = sim.workspace
     sim = flopy.mf6.MFSimulation.load(sim_ws=ws)
     gwfname = "gwf_" + name
     gwtname = "gwt_" + name
@@ -428,18 +427,16 @@ def make_plot(sim):
     return
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     makeplot = False
     if makeplot:
-        make_plot(sim)
+        make_plot(test)
 
     # ensure concentrations were saved
-    name = ex[sim.idxsim]
+    name = cases[idx]
     gwtname = "gwt_" + name
     fname = gwtname + ".mwt.bin"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
 
     # load and check the well concentrations
@@ -450,12 +447,12 @@ def eval_results(sim):
 
     # make sure concentrations can be loaded
     fname = gwtname + ".ucn"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     cobj = flopy.utils.HeadFile(fname, text="CONCENTRATION")
     caq = cobj.get_alldata()
 
     # make sure observations can be loaded
-    fpth = os.path.join(sim.simpath, gwtname + ".mwt.obs.csv")
+    fpth = os.path.join(test.workspace, gwtname + ".mwt.obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -474,17 +471,15 @@ def eval_results(sim):
     answer = np.ones(res.shape) * 1000.0
     assert np.allclose(res, answer), f"{res} {answer}"
 
-    # uncomment when testing
-    # assert False
-
 
 @pytest.mark.slow
-@pytest.mark.parametrize("name", ex)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(name, exe_dict=targets, exfunc=eval_results, idxsim=0),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_obs01.py b/autotest/test_gwt_obs01.py
index 97416f1d721..eab65a96a4a 100644
--- a/autotest/test_gwt_obs01.py
+++ b/autotest/test_gwt_obs01.py
@@ -1,7 +1,5 @@
 """
-MODFLOW 6 Autotest
 Test that the obs concentrations match the oc concentrations
-
 """
 
 import os
@@ -9,16 +7,16 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = [
+cases = [
     "gwt_obs01a",
 ]
 scheme = ["upstream"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 100
     nper = 1
     perlen = [5.0]
@@ -43,10 +41,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -242,19 +240,17 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwtname = "gwt_" + name
 
     # MODFLOW 6 output control concentrations
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     cobj = flopy.utils.HeadFile(fpth, precision="double", text="CONCENTRATION")
     conc = cobj.get_alldata()
 
     # MODFLOW 6 observation package concentrations
-    fpth = os.path.join(sim.simpath, "conc_obs.csv")
+    fpth = os.path.join(test.workspace, "conc_obs.csv")
     tc = np.genfromtxt(fpth, names=True, delimiter=",")
 
     assert np.allclose(
@@ -266,17 +262,13 @@ def eval_transport(sim):
     ), "obs concentrations do not match oc concentrations."
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_prudic2004t2.py b/autotest/test_gwt_prudic2004t2.py
index 6c052338a59..697a1b819bb 100644
--- a/autotest/test_gwt_prudic2004t2.py
+++ b/autotest/test_gwt_prudic2004t2.py
@@ -1,8 +1,10 @@
-# Second problem described by Prudic et al (2004)
-# This problem involves transport through an aquifers, lakes and streams.
-# It requires the use of the Water Mover Package to send water from a stream,
-# into a lake, and then back into another stream. Solute is also transport
-# through the system.
+"""
+Second problem described by Prudic et al (2004)
+This problem involves transport through an aquifers, lakes and streams.
+It requires the use of the Water Mover Package to send water from a stream,
+into a lake, and then back into another stream. Solute is also transport
+through the system.
+"""
 
 import os
 import sys
@@ -10,21 +12,20 @@
 import flopy
 import numpy as np
 import pytest
+
 from conftest import project_root_path
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["prudic2004t2"]
+cases = ["prudic2004t2"]
 data_path = project_root_path / "autotest" / "data"
 model_path = data_path / "prudic2004test2"
 fname = str(model_path / "lakibd.dat")
 lakibd = np.loadtxt(fname, dtype=int)
 
 
-def build_model(idx, dir):
-
-    ws = dir
-    name = ex[idx]
+def build_models(idx, test):
+    ws = test.workspace
+    name = cases[idx]
     gwfname = "gwf_" + name
     gwtname = "gwt_" + name
     sim = flopy.mf6.MFSimulation(
@@ -211,7 +212,8 @@ def build_model(idx, dir):
             budget_filerecord=gwfname + ".sfr.bud",
             mover=True,
             pname="SFR-1",
-            unit_conversion=128390.00,
+            length_conversion=3.28084,
+            time_conversion=86400.0,
             boundnames=True,
             nreaches=len(rivlist),
             packagedata=sfrpackagedata,
@@ -356,7 +358,6 @@ def build_model(idx, dir):
 
     transport = True
     if transport:
-
         gwt = flopy.mf6.ModflowGwt(sim, modelname=gwtname)
 
         # ims
@@ -586,7 +587,7 @@ def build_model(idx, dir):
 def make_concentration_vs_time(sim):
     print("making plot of concentration versus time...")
     name = sim.name
-    ws = sim.simpath
+    ws = sim.workspace
     sim = flopy.mf6.MFSimulation.load(sim_ws=ws)
     gwfname = "gwf_" + name
     gwtname = "gwt_" + name
@@ -645,7 +646,7 @@ def make_concentration_map(sim):
     ]
 
     name = sim.name
-    ws = sim.simpath
+    ws = sim.workspace
     simfp = flopy.mf6.MFSimulation.load(sim_ws=ws)
     gwfname = "gwf_" + name
     gwtname = "gwt_" + name
@@ -684,7 +685,7 @@ def make_concentration_map(sim):
 def check_obs(sim):
     print("checking obs...")
     name = sim.name
-    ws = sim.simpath
+    ws = sim.workspace
     sim = flopy.mf6.MFSimulation.load(sim_ws=ws)
     gwfname = "gwf_" + name
     gwtname = "gwt_" + name
@@ -813,27 +814,23 @@ def check_obs(sim):
 
     assert success, "One or more SFT-LKT obs checks did not pass"
 
-    return
-
-
-def eval_results(sim):
-    print("evaluating results...")
 
+def check_output(idx, test):
     makeplot = False
-    for idx, arg in enumerate(sys.argv):
+    for arg in sys.argv:
         if arg.lower() == "--makeplot":
             makeplot = True
 
     if makeplot:
-        make_concentration_vs_time(sim)
-        make_concentration_map(sim)
+        make_concentration_vs_time(test)
+        make_concentration_map(test)
 
     # ensure concentrations were saved
-    ws = sim.simpath
-    name = sim.name
+    ws = test.workspace
+    name = test.name
     gwtname = "gwt_" + name
 
-    check_obs(sim)
+    check_obs(test)
 
     fname = gwtname + ".lkt.bin"
     fname = os.path.join(ws, fname)
@@ -967,22 +964,15 @@ def eval_results(sim):
     # fname = os.path.join(ws, f"result_conc_sfr4.txt")
     # np.savetxt(fname, res_sfr4)
 
-    # uncomment when testing
-    # assert False
-
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_prudic2004t2fmi.py b/autotest/test_gwt_prudic2004t2fmi.py
index 94378e064d0..5b7c51b7ea2 100644
--- a/autotest/test_gwt_prudic2004t2fmi.py
+++ b/autotest/test_gwt_prudic2004t2fmi.py
@@ -1,4 +1,4 @@
-# tests to ability to run flow model first followed by transport model
+"""Tests to ability to run flow model first followed by transport model"""
 
 import os
 from os.path import join
@@ -6,6 +6,7 @@
 import flopy
 import numpy as np
 import pytest
+
 from conftest import project_root_path
 
 data_path = project_root_path / "autotest" / "data"
@@ -208,7 +209,8 @@ def run_flow_model(dir, exe):
             budget_filerecord=gwfname + ".sfr.bud",
             mover=True,
             pname="SFR-1",
-            unit_conversion=128390.00,
+            length_conversion=3.28084,
+            time_conversion=86400.0,
             boundnames=True,
             nreaches=len(rivlist),
             packagedata=sfrpackagedata,
@@ -783,6 +785,5 @@ def run_transport_model(dir, exe):
 
 @pytest.mark.slow
 def test_prudic2004t2fmi(function_tmpdir, targets):
-    mf6 = targets.mf6
-    run_flow_model(str(function_tmpdir), mf6)
-    run_transport_model(str(function_tmpdir), mf6)
+    run_flow_model(str(function_tmpdir), targets["mf6"])
+    run_transport_model(str(function_tmpdir), targets["mf6"])
diff --git a/autotest/test_gwt_prudic2004t2fmiats.py b/autotest/test_gwt_prudic2004t2fmiats.py
index 446aec445e8..6efdfe672f8 100644
--- a/autotest/test_gwt_prudic2004t2fmiats.py
+++ b/autotest/test_gwt_prudic2004t2fmiats.py
@@ -1,8 +1,10 @@
-# tests ats on the prudic transport model.  With these ATS settings, the
-# solver should fail on time step 19 in period 2, and should converge on the
-# second try with a smaller time step.  This test will not pass if the states
-# are not restored properly for the advanced transport packages when the
-# failure occurs.
+"""
+Tests ATS on the prudic transport model.  With these ATS settings, the
+solver should fail on time step 19 in period 2, and should converge on the
+second try with a smaller time step.  This test will not pass if the states
+are not restored properly for the advanced transport packages when the
+failure occurs.
+"""
 
 import os
 from os.path import join
@@ -10,12 +12,12 @@
 import flopy
 import numpy as np
 import pytest
+
 from conftest import project_root_path
 
 data_path = project_root_path / "autotest" / "data"
 model_path = str(data_path / "prudic2004test2")
 testgroup = "prudic2004t2fmiats"
-
 nlay = 8
 nrow = 36
 ncol = 23
@@ -212,7 +214,8 @@ def run_flow_model(dir, exe):
             budget_filerecord=gwfname + ".sfr.bud",
             mover=True,
             pname="SFR-1",
-            unit_conversion=128390.00,
+            length_conversion=3.28084,
+            time_conversion=86400.0,
             boundnames=True,
             nreaches=len(rivlist),
             packagedata=sfrpackagedata,
@@ -850,6 +853,5 @@ def run_transport_model(dir, exe):
 
 @pytest.mark.slow
 def test_prudic2004t2fmiats(function_tmpdir, targets):
-    mf6 = targets.mf6
-    run_flow_model(dir=str(function_tmpdir), exe=mf6)
-    run_transport_model(dir=str(function_tmpdir), exe=mf6)
+    run_flow_model(dir=str(function_tmpdir), exe=targets["mf6"])
+    run_transport_model(dir=str(function_tmpdir), exe=targets["mf6"])
diff --git a/autotest/test_gwt_prudic2004t2gwtgwt.py b/autotest/test_gwt_prudic2004t2gwtgwt.py
index 71577f18af4..a9ae64c41c7 100644
--- a/autotest/test_gwt_prudic2004t2gwtgwt.py
+++ b/autotest/test_gwt_prudic2004t2gwtgwt.py
@@ -1,8 +1,10 @@
-# Second problem described by Prudic et al (2004)
-# This problem involves transport through an aquifers, lakes and streams.
-# It requires the use of the Water Mover Package to send water from a stream,
-# into a lake, and then back into another stream. Solute is also transport
-# through the system.
+"""
+Second problem described by Prudic et al (2004)
+This problem involves transport through an aquifers, lakes and streams.
+It requires the use of the Water Mover Package to send water from a stream,
+into a lake, and then back into another stream. Solute is also transport
+through the system.
+"""
 
 import os
 import sys
@@ -10,13 +12,13 @@
 import flopy
 import numpy as np
 import pytest
+
 from conftest import project_root_path
 from framework import TestFramework
-from simulation import TestSimulation
 
+cases = ["prudic2004t2gwtgwt"]
 data_path = project_root_path / "autotest" / "data"
 model_path = str(data_path / "prudic2004test2gwtgwt")
-ex = ["prudic2004t2gwtgwt"]
 gwfnames = ["flow1", "flow2"]
 gwtnames = ["transport1", "transport2"]
 
@@ -56,14 +58,13 @@
 lakibd = np.loadtxt(fname, dtype=int)
 
 
-def build_model(idx, ws):
-
+def build_models(idx, test):
     name = "mf6sim"
     sim = flopy.mf6.MFSimulation(
         sim_name=name,
         version="mf6",
         exe_name="mf6",
-        sim_ws=ws,
+        sim_ws=test.workspace,
         continue_=False,
     )
     tdis_rc = [(1.0, 1, 1.0), (365.25 * 25, 25, 1.0)]
@@ -247,7 +248,7 @@ def sfr_packagedata_to_list(
         dt[14] = ("boundname", "S40")
     ra = np.genfromtxt(fname, dtype=dt)
     if convert_to_zero_base:
-        ra["rno"] -= 1
+        ra["ifno"] -= 1
         ra["layer"] -= 1
         ra["row"] -= 1
         ra["column"] -= 1
@@ -274,7 +275,6 @@ def sfr_connectiondata_to_list(fname, convert_to_zero_base=True):
 def build_gwfgwt_combo(
     sim, gwfname, gwtname, idomain, imodelcombo, icombo, imsgwf, imsgwt
 ):
-
     # number of time steps for period 2 are reduced from 12 * 25 to 25 in
     # order to speed up this autotest
 
@@ -388,7 +388,8 @@ def build_gwfgwt_combo(
                 mover=True,
                 pname=f"SFR-{isfrseg}",
                 filename=f"{gwfname}.sfr{isfrseg}",
-                unit_conversion=128390.00,
+                length_conversion=3.28084,
+                time_conversion=86400.0,
                 boundnames=False,
                 nreaches=nreaches,
                 packagedata=sfrpd,
@@ -407,7 +408,6 @@ def build_gwfgwt_combo(
             if lakibd[i, j] not in lakeibd_list:
                 continue
             else:
-
                 ilak = lakibd[i, j] - 1
                 ilak = 0
                 # back
@@ -524,7 +524,6 @@ def build_gwfgwt_combo(
         )
 
     if within_model_mvr_on:
-
         if icombo == 1:
             maxmvr, maxpackages = 1, 2
             mvrpack = [["SFR-1"], ["LAK-1"]]
@@ -548,7 +547,6 @@ def build_gwfgwt_combo(
         )
 
     if transport_on:
-
         gwt = flopy.mf6.ModflowGwt(sim, modelname=gwtname)
         sim.register_ims_package(imsgwt, [gwt.name])
 
@@ -636,7 +634,6 @@ def build_gwfgwt_combo(
 
         #
         if sft_on:
-
             if icombo == 1:
                 isfrseglist = [1]
             else:
@@ -648,8 +645,8 @@ def build_gwfgwt_combo(
                 sfrpack = gwf.get_package(pname)
                 nreaches = sfrpack.nreaches.get_data()
                 sftpackagedata = []
-                for irno in range(nreaches):
-                    t = (irno, 0.0, 99.0, 999.0, f"myreach{irno + 1}")
+                for ifno in range(nreaches):
+                    t = (ifno, 0.0, 99.0, 999.0, f"myreach{ifno + 1}")
                     sftpackagedata.append(t)
 
                 sft_obs = {
@@ -724,7 +721,6 @@ def make_concentration_vs_time(sim, ws, ans_lak1, ans_sfr3, ans_sfr4):
     sft3outflowconc = None
     sft4outflowconc = None
     if sft_on:
-
         # get southern model
         gwt = sim.get_model(gwtnames[1])
         sftpack = gwt.get_package(f"sft-3")
@@ -765,8 +761,6 @@ def make_concentration_vs_time(sim, ws, ans_lak1, ans_sfr3, ans_sfr4):
         print(f"Creating {fname}")
         plt.savefig(fname)
 
-    return
-
 
 def make_head_map(sim, ws):
     print("making head map...")
@@ -880,9 +874,7 @@ def make_concentration_map(sim, ws):
     plt.savefig(fname)
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # these answer files are results from autotest/prudic2004test2
     fname = os.path.join(model_path, "result_conc_lak1.txt")
     ans_lak1 = np.loadtxt(fname)
@@ -892,11 +884,11 @@ def eval_results(sim):
     ans_sfr4 = np.loadtxt(fname)
 
     makeplot = False
-    for idx, arg in enumerate(sys.argv):
+    for arg in sys.argv:
         if arg.lower() == "--makeplot":
             makeplot = True
 
-    ws = sim.simpath
+    ws = test.workspace
     simfp = flopy.mf6.MFSimulation.load(sim_ws=ws, strict=False)
 
     if makeplot:
@@ -906,7 +898,7 @@ def eval_results(sim):
             make_concentration_map(simfp, ws)
 
     # ensure concentrations were saved
-    ws = sim.simpath
+    ws = test.workspace
     gwfname = gwfnames[0]
     gwtname = gwtnames[0]
 
@@ -921,7 +913,6 @@ def eval_results(sim):
     sft3outflowconc = None
     sft4outflowconc = None
     if sft_on and transport_on:
-
         # get southern model
         gwt = simfp.get_model(gwtnames[1])
         sftpack = gwt.get_package(f"sft-3")
@@ -957,22 +948,15 @@ def eval_results(sim):
         msg = f"{res_sfr4} {ans_sfr4} {d}"
         assert np.allclose(res_sfr4, ans_sfr4, atol=atol), msg
 
-    # uncomment when testing
-    # assert False
-
 
 @pytest.mark.slow
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_sft01.py b/autotest/test_gwt_sft01.py
index 69228d1abcc..ef6d2f744e7 100644
--- a/autotest/test_gwt_sft01.py
+++ b/autotest/test_gwt_sft01.py
@@ -1,22 +1,24 @@
-# Simple one-layer model with sfr on top.  Purpose is to test transport in a
-# one-d sfr network.  Flows in the sfr network were specified to exactly
-# match flows in the aquifer.  A constant concentration boundary is
-# specified upgradient for both the stream and aquifer, so concentrations
-# in the stream should exactly equal the concentrations in the aquifer.
-# There is no flow between the stream and the aquifer.
+"""
+Simple one-layer model with sfr on top.  Purpose is to test transport in a
+one-d sfr network.  Flows in the sfr network were specified to exactly
+match flows in the aquifer.  A constant concentration boundary is
+specified upgradient for both the stream and aquifer, so concentrations
+in the stream should exactly equal the concentrations in the aquifer.
+There is no flow between the stream and the aquifer.
+"""
 
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["sft_01"]
+cases = ["sft_01"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     lx = 7.0
     lz = 1.0
     nlay = 1
@@ -46,10 +48,10 @@ def build_model(idx, dir):
     nouter, ninner = 700, 300
     hclose, rclose, relax = 1e-8, 1e-6, 0.97
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -365,14 +367,12 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # ensure lake concentrations were saved
-    name = sim.name
+    name = test.name
     gwtname = "gwt_" + name
     fname = gwtname + ".sft.bin"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
 
     # load the lake concentrations and make sure all values are correct
@@ -381,14 +381,14 @@ def eval_results(sim):
 
     # load the aquifer concentrations and make sure all values are correct
     fname = gwtname + ".ucn"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     cobj = flopy.utils.HeadFile(fname, text="CONCENTRATION")
     caq = cobj.get_data().flatten()
 
     assert np.allclose(csft, caq), f"{csft} {caq}"
 
     # sft observation results
-    fpth = os.path.join(sim.simpath, gwtname + ".sft.obs.csv")
+    fpth = os.path.join(test.workspace, gwtname + ".sft.obs.csv")
     try:
         tc = np.genfromtxt(fpth, names=True, delimiter=",")
     except:
@@ -402,7 +402,7 @@ def eval_results(sim):
 
     # load the sft budget file
     fname = gwtname + ".sft.bud"
-    fname = os.path.join(sim.simpath, fname)
+    fname = os.path.join(test.workspace, fname)
     assert os.path.isfile(fname)
     bobj = flopy.utils.CellBudgetFile(fname, precision="double", verbose=False)
 
@@ -421,21 +421,14 @@ def eval_results(sim):
     msg = f"{qs} /= {qa}"
     assert np.allclose(qs, qa), msg
 
-    # uncomment when testing
-    # assert False
-
-
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=0
-        ),
-        ws,
+
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_sft01gwtgwt.py b/autotest/test_gwt_sft01gwtgwt.py
index ba63d36a3a2..7ee5c4c1e1d 100644
--- a/autotest/test_gwt_sft01gwtgwt.py
+++ b/autotest/test_gwt_sft01gwtgwt.py
@@ -1,28 +1,30 @@
-# Based on sft01, but split into two gwf models and two gwt models
-# in order to test gwf-gwf and gwt-gwt.  There are sfr and sft models
-# for flow and transport.  The sfr flows and the sft concentrations
-# should match exactly with the gwf flows and the gwf concentrations.
-
-#       flow1                        flow2
-#  sfr  1 2 3 4 5 6 7  gwfgwf-mvr => 1 2 3 4 5 6 7
-#       -------------                -------------   (sfr leakance is zero so no flow between sfr and gwf)
-#  gwf  1 2 3 4 5 6 7  gwfgwf     => 1 2 3 4 5 6 7
-#           |                            |
-#  gwfgwt (flow1-transport1)    gwfgwt (flow2-transport2)
-#           |                            |
-#       transport1                   transport2
-#  sft  1 2 3 4 5 6 7  gwtgwt-mvt => 1 2 3 4 5 6 7
-#       -------------                -------------
-#  gwt  1 2 3 4 5 6 7  gwtgwt     => 1 2 3 4 5 6 7
+"""
+Based on sft01, but split into two gwf models and two gwt models
+in order to test gwf-gwf and gwt-gwt.  There are sfr and sft models
+for flow and transport.  The sfr flows and the sft concentrations
+should match exactly with the gwf flows and the gwf concentrations.
+
+      flow1                        flow2
+ sfr  1 2 3 4 5 6 7  gwfgwf-mvr => 1 2 3 4 5 6 7
+      -------------                -------------   (sfr leakance is zero so no flow between sfr and gwf)
+ gwf  1 2 3 4 5 6 7  gwfgwf     => 1 2 3 4 5 6 7
+          |                            |
+ gwfgwt (flow1-transport1)    gwfgwt (flow2-transport2)
+          |                            |
+      transport1                   transport2
+ sft  1 2 3 4 5 6 7  gwtgwt-mvt => 1 2 3 4 5 6 7
+      -------------                -------------
+ gwt  1 2 3 4 5 6 7  gwtgwt     => 1 2 3 4 5 6 7
+"""
 
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["sft01gwtgwt"]
+cases = ["sft01gwtgwt"]
 
 # properties for each model combination
 lx = 7.0
@@ -59,14 +61,13 @@
 across_model_mvt_on = True and across_model_mvr_on
 
 
-def build_model(idx, ws):
-
+def build_models(idx, test):
     name = "mf6sim"
     sim = flopy.mf6.MFSimulation(
         sim_name=name,
         version="mf6",
         exe_name="mf6",
-        sim_ws=ws,
+        sim_ws=test.workspace,
         continue_=False,
     )
 
@@ -180,8 +181,7 @@ def build_model(idx, ws):
         mvrspd = [
             ["flow1", "sfr-1", ncol - 1, "flow2", "sfr-1", 0, "FACTOR", 1.00]
         ]
-        mvr = flopy.mf6.ModflowMvr(
-            sim,
+        gwfgwf.mvr.initialize(
             modelnames=True,
             maxmvr=maxmvr,
             print_flows=True,
@@ -212,14 +212,13 @@ def build_model(idx, ws):
 
     # simulation GWT-GWT Mover
     if across_model_mvt_on:
-        mvt = flopy.mf6.modflow.ModflowGwtmvt(sim, filename=mvt_filerecord)
+        gwtgwt.mvt.initialize(filename=mvt_filerecord)
 
     regression = None
     return sim, regression
 
 
 def build_gwfgwt_combo(sim, gwfname, gwtname, icombo):
-
     # create gwf model
     gwf = flopy.mf6.ModflowGwf(sim, modelname=gwfname)
 
@@ -481,18 +480,16 @@ def build_gwfgwt_combo(sim, gwfname, gwtname, icombo):
     return sim, None
 
 
-def eval_results(sim):
-    print("evaluating results...")
-
+def check_output(idx, test):
     # load the simulations
-    ws = sim.simpath
-    sim = flopy.mf6.MFSimulation.load(sim_ws=ws)
+    ws = test.workspace
+    test = flopy.mf6.MFSimulation.load(sim_ws=ws)
 
     # construct head and conc for combined models
-    gwf1 = sim.gwf[0]
-    gwf2 = sim.gwf[1]
-    gwt1 = sim.gwt[0]
-    gwt2 = sim.gwt[1]
+    gwf1 = test.gwf[0]
+    gwf2 = test.gwf[1]
+    gwt1 = test.gwt[0]
+    gwt2 = test.gwt[1]
     head = list(gwf1.output.head().get_data().flatten()) + list(
         gwf2.output.head().get_data().flatten()
     )
@@ -513,17 +510,13 @@ def eval_results(sim):
     ), "aquifer concentration does not equal sfr concentration"
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_results, idxsim=idx
-        ),
-        ws,
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_src01.py b/autotest/test_gwt_src01.py
index 1535cdbd909..7f3f5ceb905 100644
--- a/autotest/test_gwt_src01.py
+++ b/autotest/test_gwt_src01.py
@@ -4,21 +4,20 @@
 on the right side.  The simulation time is set to be large so that the result
 is a linear gradient in concentration that can be calculated from a simple
 diffusion equation of the form, F = D * (c1 - c0) / L.
-
 """
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["src01a"]
+cases = ["src01a"]
 xt3d = [False]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 1, 1, 100
     nper = 1
     perlen = [1.0e10]
@@ -46,10 +45,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -238,13 +237,11 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwtname = "gwt_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     cobj = flopy.utils.HeadFile(fpth, precision="double", text="CONCENTRATION")
     conc = cobj.get_data()
 
@@ -256,17 +253,13 @@ def eval_transport(sim):
     ), "simulated concentrations do not match with known solution."
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_ssm01fmi.py b/autotest/test_gwt_ssm01fmi.py
index f25cb062679..6da7ac1a95c 100644
--- a/autotest/test_gwt_ssm01fmi.py
+++ b/autotest/test_gwt_ssm01fmi.py
@@ -1,7 +1,9 @@
-# multiple ssm sources and sinks using a flow model followed by a
-# transport model.  Initial conditions and all inflows and outflows are
-# assigned a concentration of 100.0 so the simulated concentration must also
-# be 100.
+"""
+multiple ssm sources and sinks using a flow model followed by a
+transport model.  Initial conditions and all inflows and outflows are
+assigned a concentration of 100.0 so the simulated concentration must also
+be 100.
+"""
 
 import os
 from os.path import join
@@ -310,6 +312,5 @@ def run_transport_model(dir, exe):
 
 
 def test_ssm01fmi(function_tmpdir, targets):
-    mf6 = targets.mf6
-    run_flow_model(str(function_tmpdir), mf6)
-    run_transport_model(str(function_tmpdir), mf6)
+    run_flow_model(str(function_tmpdir), targets["mf6"])
+    run_transport_model(str(function_tmpdir), targets["mf6"])
diff --git a/autotest/test_gwt_ssm02.py b/autotest/test_gwt_ssm02.py
index 251bd3dc49c..03e8b73dcc0 100644
--- a/autotest/test_gwt_ssm02.py
+++ b/autotest/test_gwt_ssm02.py
@@ -4,7 +4,6 @@
 will cause the concentration to increase.  Then for the second stress period
 add recharge water with a concentration of zero which will dilute the solute
 concentration.  Simulation results are compared against a simple calculation.
-
 """
 
 import os
@@ -12,18 +11,17 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["ssm02"]
+cases = ["ssm02"]
 laytyp = [1]
 ss = [1.0e-10]
 sy = [0.1]
 nlay, nrow, ncol = 1, 1, 1
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     nper = 2
     perlen = [2.0, 2.0]
     nstp = [14, 14]
@@ -42,10 +40,10 @@ def build_model(idx, dir):
     for id in range(nper):
         tdis_rc.append((perlen[id], nstp[id], tsmult[id]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -217,18 +215,16 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwtname = "gwt_" + name
     gwfname = "gwf_" + name
 
-    fpth = os.path.join(sim.simpath, f"{gwfname}.hds")
+    fpth = os.path.join(test.workspace, f"{gwfname}.hds")
     hobj = flopy.utils.HeadFile(fpth, precision="double")
     head = hobj.get_alldata().flatten()
 
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     cobj = flopy.utils.HeadFile(fpth, precision="double", text="CONCENTRATION")
     conc = cobj.get_alldata().flatten()
 
@@ -252,17 +248,13 @@ def eval_transport(sim):
         vold = v
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_ssm03.py b/autotest/test_gwt_ssm03.py
index 02f8c05fad9..150e392be45 100644
--- a/autotest/test_gwt_ssm03.py
+++ b/autotest/test_gwt_ssm03.py
@@ -1,8 +1,6 @@
 """
-MODFLOW 6 Autotest
 Test the SSM FILEINPUT option for specifying source and sink
 concentrations.
-
 """
 
 import os
@@ -10,13 +8,13 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["ssm03"]
+cases = ["ssm03"]
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     nlay, nrow, ncol = 3, 5, 5
     perlen = [5.0]
     nstp = [5]
@@ -37,10 +35,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -229,19 +227,17 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwtname = "gwt_" + name
 
     # load concentration file
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     cobj = flopy.utils.HeadFile(fpth, precision="double", text="CONCENTRATION")
     conc = cobj.get_data()
 
     # load transport budget file
-    fpth = os.path.join(sim.simpath, f"{gwtname}.cbc")
+    fpth = os.path.join(test.workspace, f"{gwtname}.cbc")
     bobj = flopy.utils.CellBudgetFile(
         fpth,
         precision="double",
@@ -249,7 +245,6 @@ def eval_transport(sim):
 
     ssmbudall = bobj.get_data(text="SOURCE-SINK MIX")
     for ssmbud in ssmbudall:
-
         node, node2, q = ssmbud[0]
         assert node == 25, "node location for well must be 25 (GWT cell 25)"
         assert node2 == 1, "node2 location for well must be 1 (first well)"
@@ -261,17 +256,13 @@ def eval_transport(sim):
         assert q < 0.0, "mass flux for chd must be less than zero"
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_ssm04.py b/autotest/test_gwt_ssm04.py
index df3b02ebdda..2448c7b437d 100644
--- a/autotest/test_gwt_ssm04.py
+++ b/autotest/test_gwt_ssm04.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 Test the SSM FILEINPUT option for specifying source and sink
 concentrations.
 
@@ -8,7 +7,6 @@
 2.  array-based recharge, no time array series
 3.  list-based recharge with time series
 4.  array-based recharge with time array series
-
 """
 
 import os
@@ -16,10 +14,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["ssm04"]
+cases = ["ssm04"]
 
 nlay, nrow, ncol = 3, 5, 5
 idomain_lay0 = [
@@ -33,7 +31,7 @@
 idomain[0, :, :] = np.array(idomain_lay0)
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     perlen = [5.0, 5.0, 5.0]
     nstp = [5, 5, 5]
     tsmult = [1.0, 1.0, 1.0]
@@ -53,10 +51,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -168,7 +166,7 @@ def build_model(idx, dir):
             nodeu = i * nrow + j
             tsnames.append(f"rch-{nodeu + 1}")
     ts_data = []
-    totim = 0.
+    totim = 0.0
     for kper in range(nper):
         totim += perlen[kper]
     for t in [0, totim]:
@@ -330,7 +328,7 @@ def build_model(idx, dir):
             nodeu = i * ncol + j
             tsnames.append(f"crch-{nodeu + 1}")
     ts_data = [tuple([0.0] + list(range(1, nrow * ncol + 1)))]
-    for t in [5., 10., 15.]:
+    for t in [5.0, 10.0, 15.0]:
         ts = tuple([float(t)] + list(range(1, nrow * ncol + 1)))
         ts_data.append(ts)
     ts_dict = {
@@ -360,7 +358,7 @@ def build_model(idx, dir):
     # for now write the recharge concentration to a dat file because there
     # is a bug in flopy that will not correctly write this array as internal
     tas_array = {
-        0.0: f"{gwtname}.rch4.spc.tas.dat", 
+        0.0: f"{gwtname}.rch4.spc.tas.dat",
         5.0: f"{gwtname}.rch4.spc.tas.dat",
         10.0: f"{gwtname}.rch4.spc.tas.dat",
         15.0: f"{gwtname}.rch4.spc.tas.dat",
@@ -419,19 +417,17 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwtname = "gwt_" + name
 
     # load concentration file
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     cobj = flopy.utils.HeadFile(fpth, precision="double", text="CONCENTRATION")
     conc = cobj.get_data()
 
     # load transport budget file
-    fpth = os.path.join(sim.simpath, f"{gwtname}.cbc")
+    fpth = os.path.join(test.workspace, f"{gwtname}.cbc")
     bobj = flopy.utils.CellBudgetFile(
         fpth,
         precision="double",
@@ -505,17 +501,13 @@ def eval_transport(sim):
             istart = istop
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_ssm04fmi.py b/autotest/test_gwt_ssm04fmi.py
index 5950d5b3a64..a43c9074f29 100644
--- a/autotest/test_gwt_ssm04fmi.py
+++ b/autotest/test_gwt_ssm04fmi.py
@@ -1,5 +1,4 @@
 """
-MODFLOW 6 Autotest
 Test the SSM FILEINPUT option for specifying source and sink
 concentrations.
 
@@ -8,7 +7,6 @@
 2.  array-based recharge, no time array series
 3.  list-based recharge with time series
 4.  array-based recharge with time array series
-
 """
 
 import os
@@ -17,8 +15,6 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
 testgroup = "ssm04fmi"
 
@@ -50,8 +46,8 @@
 recharge_package_3 = False
 recharge_package_4 = False
 
-def run_flow_model(dir, exe):
 
+def run_flow_model(dir, exe):
     name = "flow"
     gwfname = name
     wsf = join(dir, testgroup, name)
@@ -175,7 +171,7 @@ def run_flow_model(dir, exe):
             nodeu = i * nrow + j
             tsnames.append(f"rch-{nodeu + 1}")
     ts_data = []
-    totim = 0.
+    totim = 0.0
     for kper in range(nper):
         totim += perlen[kper]
     for t in [0, totim]:
@@ -226,7 +222,9 @@ def run_flow_model(dir, exe):
             interpolation_methodrecord=interpolation_methodrecord,
         )
         np.savetxt(
-            os.path.join(wsf, f"{gwfname}.rch4.tas.dat"), recharge_rate, fmt="%7.1f"
+            os.path.join(wsf, f"{gwfname}.rch4.tas.dat"),
+            recharge_rate,
+            fmt="%7.1f",
         )
 
     # output control
@@ -246,7 +244,6 @@ def run_flow_model(dir, exe):
 
 
 def run_transport_model(dir, exe):
-
     name = "transport"
     gwtname = name
     wst = join(dir, testgroup, name)
@@ -368,7 +365,7 @@ def run_transport_model(dir, exe):
             nodeu = i * ncol + j
             tsnames.append(f"crch-{nodeu + 1}")
     ts_data = [tuple([0.0] + list(range(1, nrow * ncol + 1)))]
-    for t in [5., 10., 15.]:
+    for t in [5.0, 10.0, 15.0]:
         ts = tuple([float(t)] + list(range(1, nrow * ncol + 1)))
         ts_data.append(ts)
     ts_dict = {
@@ -400,7 +397,7 @@ def run_transport_model(dir, exe):
         # for now write the recharge concentration to a dat file because there
         # is a bug in flopy that will not correctly write this array as internal
         tas_array = {
-            0.0: f"{gwtname}.rch4.spc.tas.dat", 
+            0.0: f"{gwtname}.rch4.spc.tas.dat",
             5.0: f"{gwtname}.rch4.spc.tas.dat",
             10.0: f"{gwtname}.rch4.spc.tas.dat",
             15.0: f"{gwtname}.rch4.spc.tas.dat",
@@ -413,7 +410,9 @@ def run_transport_model(dir, exe):
             time_series_namerecord=time_series_namerecord,
             interpolation_methodrecord=interpolation_methodrecord,
         )
-        recharge_concentration = np.arange(nrow * ncol).reshape((nrow, ncol)) + 1
+        recharge_concentration = (
+            np.arange(nrow * ncol).reshape((nrow, ncol)) + 1
+        )
         np.savetxt(
             os.path.join(wst, f"{gwtname}.rch4.spc.tas.dat"),
             recharge_concentration,
@@ -464,8 +463,8 @@ def run_transport_model(dir, exe):
     eval_transport(wst)
     return
 
+
 def eval_transport(wst):
-    print("evaluating transport...")
     gwtname = "transport"
 
     # load concentration file
@@ -490,7 +489,7 @@ def eval_transport(wst):
         # Check records for each of the four recharge packages
         ssmbud = ssmbudall[itime]
         istart = 0
-        for irchpak in [2]: # [1, 2, 3, 4]:
+        for irchpak in [2]:  # [1, 2, 3, 4]:
             print(f"  Checking records for recharge package {irchpak}")
             istop = istart + 23
 
@@ -551,6 +550,5 @@ def eval_transport(wst):
 
 
 def test_ssm04fmi(function_tmpdir, targets):
-    mf6 = targets.mf6
-    run_flow_model(str(function_tmpdir), mf6)
-    run_transport_model(str(function_tmpdir), mf6)
+    run_flow_model(str(function_tmpdir), targets["mf6"])
+    run_transport_model(str(function_tmpdir), targets["mf6"])
diff --git a/autotest/test_gwt_ssm05.py b/autotest/test_gwt_ssm05.py
index 0945813cbd9..229b14bd757 100644
--- a/autotest/test_gwt_ssm05.py
+++ b/autotest/test_gwt_ssm05.py
@@ -1,8 +1,6 @@
 """
-MODFLOW 6 Autotest
 Test the SSM package auxiliary variables for specifying source and sink
 concentrations for array based recharge.
-
 """
 
 import os
@@ -10,10 +8,10 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["ssm05"]
+cases = ["ssm05"]
 
 nlay, nrow, ncol = 3, 5, 5
 idomain_lay0 = [
@@ -27,7 +25,7 @@
 idomain[0, :, :] = np.array(idomain_lay0)
 
 
-def build_model(idx, dir):
+def build_models(idx, test):
     perlen = [5.0]
     nstp = [5]
     tsmult = [1.0]
@@ -47,10 +45,10 @@ def build_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -238,19 +236,17 @@ def build_model(idx, dir):
     return sim, None
 
 
-def eval_transport(sim):
-    print("evaluating transport...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwtname = "gwt_" + name
 
     # load concentration file
-    fpth = os.path.join(sim.simpath, f"{gwtname}.ucn")
+    fpth = os.path.join(test.workspace, f"{gwtname}.ucn")
     cobj = flopy.utils.HeadFile(fpth, precision="double", text="CONCENTRATION")
     conc = cobj.get_data()
 
     # load transport budget file
-    fpth = os.path.join(sim.simpath, f"{gwtname}.cbc")
+    fpth = os.path.join(test.workspace, f"{gwtname}.cbc")
     bobj = flopy.utils.CellBudgetFile(
         fpth,
         precision="double",
@@ -314,17 +310,13 @@ def eval_transport(sim):
             istart = istop
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_transport, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_ssm06.py b/autotest/test_gwt_ssm06.py
index 1371aec43e2..6dccd9202d9 100644
--- a/autotest/test_gwt_ssm06.py
+++ b/autotest/test_gwt_ssm06.py
@@ -1,5 +1,7 @@
-# Derived from test_gwt_ssm01fmi.py, but drops RIV and adds SFR.
-# See test_gwt_ssm06fmi.py for additional detail on what this test is about.
+"""
+Derived from test_gwt_ssm01fmi.py, but drops RIV and adds SFR.
+See test_gwt_ssm06fmi.py for additional detail on what this test is about.
+"""
 
 import os
 
@@ -16,11 +18,9 @@
 top = 100.0
 botm = 0.0
 
-#
 # Add SFR for serving as a MVR receiver (something's up when multiple packages
 # appear in SSM and MVR is active. When MVR is inactive, all seem to work well.
 # However, things break as soon as MVR is activated.
-#
 
 conns = [(0, -1), (1, 0, -2), (2, 1, -3), (3, 2, -4), (4, 3)]
 
@@ -189,7 +189,8 @@ def run_flw_and_trnprt_models(dir, exe):
         budget_filerecord=gwfname + ".sfr.bud",
         save_flows=True,
         pname="SFR-1",
-        unit_conversion=86400.0 * 1.486,
+        length_conversion=3.28084,
+        time_conversion=86400.0,
         boundnames=False,
         nreaches=len(conns),
         packagedata=sfr_pkdat,
@@ -347,5 +348,4 @@ def run_flw_and_trnprt_models(dir, exe):
 
 
 def test_ssm06(function_tmpdir, targets):
-    mf6 = targets.mf6
-    run_flw_and_trnprt_models(str(function_tmpdir), mf6)
+    run_flw_and_trnprt_models(str(function_tmpdir), targets["mf6"])
diff --git a/autotest/test_gwt_ssm06fmi.py b/autotest/test_gwt_ssm06fmi.py
index 372b1efd1d4..c7e74a3c176 100644
--- a/autotest/test_gwt_ssm06fmi.py
+++ b/autotest/test_gwt_ssm06fmi.py
@@ -1,11 +1,13 @@
-# Derived from test_gwt_ssm01fmi.py, but drops RIV and adds SFR.
-# In that autotest, flow and transport run separately, which is the case here
-# as well. However, by adding SFR we can now invoke MVR, in this case
-# WEL -> SFR at the same time as invoking auxiliary variables.  A
-# companion autotest runs this same simulation (uses SFR in place of RIV for
-# receiving MVR water), but runs both flow and tranport simultaneously which,
-# at one time, wrongly threw an input error.  However, running the models
-# separately never threw the error.
+"""
+Derived from test_gwt_ssm01fmi.py, but drops RIV and adds SFR.
+In that autotest, flow and transport run separately, which is the case here
+as well. However, by adding SFR we can now invoke MVR, in this case
+WEL -> SFR at the same time as invoking auxiliary variables.  A
+companion autotest runs this same simulation (uses SFR in place of RIV for
+receiving MVR water), but runs both flow and tranport simultaneously which,
+at one time, wrongly threw an input error.  However, running the models
+separately never threw the error.
+"""
 
 import os
 
@@ -22,11 +24,9 @@
 top = 100.0
 botm = 0.0
 
-#
 # Add SFR for serving as a MVR receiver (something's up when multiple packages
 # appear in SSM and MVR is active. When MVR is inactive, all seem to work well.
 # However, things break as soon as MVR is activated.
-#
 
 conns = [(0, -1), (1, 0, -2), (2, 1, -3), (3, 2, -4), (4, 3)]
 
@@ -204,7 +204,8 @@ def run_flow_model(dir, exe):
         budget_filerecord=gwfname + ".sfr.bud",
         save_flows=True,
         pname="SFR-1",
-        unit_conversion=86400.0 * 1.486,
+        length_conversion=3.28084,
+        time_conversion=86400.0,
         boundnames=False,
         nreaches=len(conns),
         packagedata=sfr_pkdat,
@@ -380,6 +381,5 @@ def run_transport_model(dir, exe):
 
 
 def test_ssm06fmi(function_tmpdir, targets):
-    mf6 = targets.mf6
-    run_flow_model(str(function_tmpdir), mf6)
-    run_transport_model(str(function_tmpdir), mf6)
+    run_flow_model(str(function_tmpdir), targets["mf6"])
+    run_transport_model(str(function_tmpdir), targets["mf6"])
diff --git a/autotest/test_gwt_uzt01.py b/autotest/test_gwt_uzt01.py
index 50f1f482bb9..7f2837ef035 100644
--- a/autotest/test_gwt_uzt01.py
+++ b/autotest/test_gwt_uzt01.py
@@ -1,9 +1,8 @@
 """
-# Test uzt for one-d transport in a vertical column.  This problem is based
+Test uzt for one-d transport in a vertical column.  This problem is based
 on test_gwf_uzf03.py.  Infiltration is assigned a concentration of 100.  The
-# uzet concentration is also assigned as 100. so that the calculated uzf cells
-# should have a concentration of 100.
-
+uzet concentration is also assigned as 100. so that the calculated uzf cells
+should have a concentration of 100.
 """
 
 import os
@@ -11,15 +10,14 @@
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
 
-ex = ["uzt01a"]
+cases = ["uzt01a"]
 nlay, nrow, ncol = 15, 1, 1
 
 
-def build_model(idx, dir):
-
+def build_models(idx, test):
     perlen = [17.7]
     nper = len(perlen)
     nstp = [177]
@@ -49,10 +47,10 @@ def build_model(idx, dir):
     for id in range(nper):
         tdis_rc.append((perlen[id], nstp[id], tsmult[id]))
 
-    name = ex[idx]
+    name = cases[idx]
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
         sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
@@ -379,14 +377,14 @@ def make_plot(sim, obsvals):
     print("making plots...")
 
     name = sim.name
-    ws = sim.simpath
+    ws = sim.workspace
 
     # shows curves for times 2.5, 7.5, 12.6, 17.7
     # which are indices 24, 74, 125, and -1
-    idx = [24, 74, 125, -1]
+    indices = [24, 74, 125, -1]
 
     obsvals = [list(row) for row in obsvals]
-    obsvals = [obsvals[i] for i in idx]
+    obsvals = [obsvals[i] for i in indices]
     obsvals = np.array(obsvals)
 
     import matplotlib.pyplot as plt
@@ -414,7 +412,7 @@ def make_plot(sim, obsvals):
 def check_obs(sim):
     print("checking obs...")
     name = sim.name
-    ws = sim.simpath
+    ws = sim.workspace
     sim = flopy.mf6.MFSimulation.load(sim_ws=ws)
     gwfname = "gwf_" + name
     gwtname = "gwt_" + name
@@ -485,13 +483,11 @@ def check_obs(sim):
     assert success, "One or more UZT obs checks did not pass"
 
 
-def eval_flow(sim):
-    print("evaluating flow...")
-
-    name = sim.name
+def check_output(idx, test):
+    name = test.name
     gwfname = "gwf_" + name
     gwtname = "gwt_" + name
-    ws = sim.simpath
+    ws = test.workspace
 
     # check binary grid file
     fname = os.path.join(ws, gwfname + ".dis.grb")
@@ -553,26 +549,22 @@ def eval_flow(sim):
     assert np.allclose(c, canswer)
 
     # check observations
-    check_obs(sim)
+    check_obs(test)
 
     # Make plot of obs
-    fpth = os.path.join(sim.simpath, gwtname + ".uzt.obs.concentration.csv")
+    fpth = os.path.join(test.workspace, gwtname + ".uzt.obs.concentration.csv")
     obsvals = np.genfromtxt(fpth, names=True, delimiter=",")
 
     # make_plot(sim, obsvals)
 
 
-@pytest.mark.parametrize(
-    "name",
-    ex,
-)
-def test_mf6model(name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, 0, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_flow, idxsim=0
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
     )
+    test.run()
diff --git a/autotest/test_gwt_zb01.py b/autotest/test_gwt_zb01.py
index 8bd78e8d48c..b0e2956f047 100644
--- a/autotest/test_gwt_zb01.py
+++ b/autotest/test_gwt_zb01.py
@@ -1,6 +1,7 @@
-# test that zonebudget works on a cell budget file from GWT
-# https://github.com/MODFLOW-USGS/modflow6/discussions/1181
-
+"""
+Test that zonebudget works on a cell budget file from GWT
+https://github.com/MODFLOW-USGS/modflow6/discussions/1181
+"""
 
 import os
 from pathlib import Path
@@ -8,18 +9,14 @@
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
+from framework import TestFramework
 
-name = "zbud6_zb01"
+cases = ["zbud6_zb01"]
 htol = None
 dtol = 1e-3
 budtol = 1e-2
-bud_lst = [
-    "STORAGE-AQUEOUS_IN",
-    "STORAGE-AQUEOUS_OUT"
-]
+bud_lst = ["STORAGE-AQUEOUS_IN", "STORAGE-AQUEOUS_OUT"]
 zone_lst = []
 for n in bud_lst:
     s = n.replace("_", "-")
@@ -44,7 +41,8 @@
 size3d = nlay * nrow * ncol
 
 
-def build_model(dir, exe):
+def build_models(idx, test):
+    name = cases[idx]
     perlen = [timetoend]
     nstp = [50]
     tsmult = [1.0]
@@ -58,9 +56,9 @@ def build_model(dir, exe):
         tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
 
     # build MODFLOW 6 files
-    ws = dir
+    ws = test.workspace
     sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name=exe, sim_ws=ws
+        sim_name=name, version="mf6", exe_name="mf6", sim_ws=ws
     )
     # create tdis package
     tdis = flopy.mf6.ModflowTdis(
@@ -108,11 +106,18 @@ def build_model(dir, exe):
     w = {0: wellist}
 
     # grid discretization
-    dis = flopy.mf6.ModflowGwfdis(gwf, nlay=nlay, nrow=nrow, ncol=ncol,
-                                 delr=delr, delc=delc,
-                                 top=top, botm=botm,
-                                 idomain=np.ones((nlay, nrow, ncol), dtype=int),
-                                 filename=f"{gwfname}.dis")
+    dis = flopy.mf6.ModflowGwfdis(
+        gwf,
+        nlay=nlay,
+        nrow=nrow,
+        ncol=ncol,
+        delr=delr,
+        delc=delc,
+        top=top,
+        botm=botm,
+        idomain=np.ones((nlay, nrow, ncol), dtype=int),
+        filename=f"{gwfname}.dis",
+    )
 
     # initial conditions
     ic = flopy.mf6.ModflowGwfic(gwf, strt=strt, filename=f"{gwfname}.ic")
@@ -188,11 +193,18 @@ def build_model(dir, exe):
     sim.register_ims_package(imsgwt, [gwt.name])
 
     # gwt grid discretization
-    dis = flopy.mf6.ModflowGwtdis(gwt, nlay=nlay, nrow=nrow, ncol=ncol,
-                                 delr=delr, delc=delc,
-                                 top=top, botm=botm,
-                                 idomain=np.ones((nlay, nrow, ncol), dtype=int),
-                                 filename=f"{gwtname}.dis")
+    dis = flopy.mf6.ModflowGwtdis(
+        gwt,
+        nlay=nlay,
+        nrow=nrow,
+        ncol=ncol,
+        delr=delr,
+        delc=delc,
+        top=top,
+        botm=botm,
+        idomain=np.ones((nlay, nrow, ncol), dtype=int),
+        filename=f"{gwtname}.dis",
+    )
 
     # initial conditions
     ic = flopy.mf6.ModflowGwtic(gwt, strt=0.0, filename=f"{gwtname}.ic")
@@ -235,22 +247,21 @@ def build_model(dir, exe):
     return sim, None
 
 
-def eval_zb6(sim, exe):
-    print("evaluating zonebudget...")
-    ws = Path(sim.simpath)
+def check_output(idx, test):
+    ws = Path(test.workspace)
 
     # build zonebudget files
     # start with 1 since budget isn't calculated for zone 0
-    zones = [k + 1 for k in range(nlay)]  
+    zones = [k + 1 for k in range(nlay)]
     nzones = len(zones)
     with open(ws / "zonebudget.nam", "w") as f:
         f.write("BEGIN ZONEBUDGET\n")
-        f.write(f"  BUD gwt_{sim.name}.cbc\n")
-        f.write(f"  ZON {sim.name}.zon\n")
-        f.write(f"  GRB gwf_{sim.name}.dis.grb\n")
+        f.write(f"  BUD gwt_{test.name}.cbc\n")
+        f.write(f"  ZON {test.name}.zon\n")
+        f.write(f"  GRB gwf_{test.name}.dis.grb\n")
         f.write("END ZONEBUDGET\n")
 
-    with open(ws / f"{sim.name}.zon", "w") as f:
+    with open(ws / f"{test.name}.zon", "w") as f:
         f.write("BEGIN DIMENSIONS\n")
         f.write(f"  NCELLS {size3d}\n")
         f.write("END DIMENSIONS\n\n")
@@ -262,7 +273,7 @@ def eval_zb6(sim, exe):
 
     # run zonebudget
     success, buff = flopy.run_model(
-        exe,
+        test.targets["zbud6"],
         "zonebudget.nam",
         model_ws=ws,
         silent=False,
@@ -270,10 +281,12 @@ def eval_zb6(sim, exe):
     )
 
     assert success
-    sim.success = success
+    test.success = success
 
     # read data from csv file
-    zbd = np.genfromtxt(ws / "zonebudget.csv", names=True, delimiter=",", deletechars="")
+    zbd = np.genfromtxt(
+        ws / "zonebudget.csv", names=True, delimiter=",", deletechars=""
+    )
 
     # sum the data for all zones
     nentries = int(zbd.shape[0] / nzones)
@@ -297,8 +310,8 @@ def eval_zb6(sim, exe):
     # get results from listing file
     # todo: should flopy have a subclass for GWT list file?
     budl = flopy.utils.mflistfile.ListBudget(
-        ws / f"gwt_{os.path.basename(sim.name)}.lst",
-        budgetkey="MASS BUDGET FOR ENTIRE MODEL"
+        ws / f"gwt_{os.path.basename(test.name)}.lst",
+        budgetkey="MASS BUDGET FOR ENTIRE MODEL",
     )
     names = list(bud_lst)
     found_names = budl.get_record_names()
@@ -307,19 +320,17 @@ def eval_zb6(sim, exe):
     nbud = d0.shape[0]
 
     # get results from cbc file
-    cbc_bud = [
-        "STORAGE-AQUEOUS"
-    ]
+    cbc_bud = ["STORAGE-AQUEOUS"]
     d = np.recarray(nbud, dtype=dtype)
     for key in bud_lst:
         d[key] = 0.0
     cobj = flopy.utils.CellBudgetFile(
-        ws / f"gwt_{os.path.basename(sim.name)}.cbc",
-        precision="double")
+        ws / f"gwt_{os.path.basename(test.name)}.cbc", precision="double"
+    )
     rec = cobj.list_records()
     kk = cobj.get_kstpkper()
     times = cobj.get_times()
-    for idx, (k, t) in enumerate(zip(kk, times)):
+    for i, (k, t) in enumerate(zip(kk, times)):
         for text in cbc_bud:
             qin = 0.0
             qout = 0.0
@@ -337,86 +348,81 @@ def eval_zb6(sim, exe):
                             qout -= vv
                         else:
                             qin += vv
-            d["totim"][idx] = t
-            d["time_step"][idx] = k[0]
+            d["totim"][i] = t
+            d["time_step"][i] = k[0]
             d["stress_period"] = k[1]
             key = f"{text}_IN"
-            d[key][idx] = qin
+            d[key][i] = qin
             key = f"{text}_OUT"
-            d[key][idx] = qout
+            d[key][i] = qout
 
     # calculate absolute difference
     diff = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, key in enumerate(bud_lst):
-        diff[:, idx] = d0[key] - d[key]
+    for i, key in enumerate(bud_lst):
+        diff[:, i] = d0[key] - d[key]
     diffmax = np.abs(diff).max()
     msg = f"maximum absolute total-budget difference ({diffmax}) "
 
     # write summary
-    with open(ws / f"{os.path.basename(sim.name)}.bud.cmp.out", "w") as f:
+    with open(ws / f"{os.path.basename(test.name)}.bud.cmp.out", "w") as f:
         for i in range(diff.shape[0]):
             if i == 0:
                 line = f"{'TIME':>10s}"
-                for idx, key in enumerate(bud_lst):
+                for key in bud_lst:
                     line += f"{key + '_LST':>25s}"
                     line += f"{key + '_CBC':>25s}"
                     line += f"{key + '_DIF':>25s}"
                 f.write(line + "\n")
             line = f"{d['totim'][i]:10g}"
-            for idx, key in enumerate(bud_lst):
+            for ii, key in enumerate(bud_lst):
                 line += f"{d0[key][i]:25g}"
                 line += f"{d[key][i]:25g}"
-                line += f"{diff[i, idx]:25g}"
+                line += f"{diff[i, ii]:25g}"
             f.write(line + "\n")
 
     # compare zone budget output to cbc output
     diffzb = np.zeros((nbud, len(bud_lst)), dtype=float)
-    for idx, (key0, key) in enumerate(zip(zone_lst, bud_lst)):
-        diffzb[:, idx] = zbsum[key0] - d[key]
+    for i, (key0, key) in enumerate(zip(zone_lst, bud_lst)):
+        diffzb[:, i] = zbsum[key0] - d[key]
     diffzbmax = np.abs(diffzb).max()
     msg += (
         f"\nmaximum absolute zonebudget-cell by cell difference ({diffzbmax}) "
     )
 
     # write summary
-    with open(ws / f"{os.path.basename(sim.name)}.zbud.cmp.out", "w") as f:
+    with open(ws / f"{os.path.basename(test.name)}.zbud.cmp.out", "w") as f:
         for i in range(diff.shape[0]):
             if i == 0:
                 line = f"{'TIME':>10s}"
-                for idx, key in enumerate(bud_lst):
+                for key in bud_lst:
                     line += f"{key + '_ZBUD':>25s}"
                     line += f"{key + '_CBC':>25s}"
                     line += f"{key + '_DIF':>25s}"
                 f.write(line + "\n")
             line = f"{d['totim'][i]:10g}"
-            for idx, (key0, key) in enumerate(zip(zone_lst, bud_lst)):
+            for ii, (key0, key) in enumerate(zip(zone_lst, bud_lst)):
                 line += f"{zbsum[key0][i]:25g}"
                 line += f"{d[key][i]:25g}"
-                line += f"{diffzb[i, idx]:25g}"
+                line += f"{diffzb[i, ii]:25g}"
             f.write(line + "\n")
 
     if diffmax > budtol or diffzbmax > budtol:
-        sim.success = False
+        test.success = False
         msg += f"\n...exceeds {budtol}"
         assert diffmax < budtol and diffzbmax < budtol, msg
     else:
-        sim.success = True
+        test.success = True
         print("    " + msg)
 
 
-def test_mf6model(function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    mf6 = targets.mf6
-    zb6 = targets.zbud6
-    test = TestFramework()
-    test.build(lambda _, w: build_model(w, mf6), 0, ws)
-    test.run(
-        TestSimulation(
-            name=name,
-            exe_dict=targets,
-            exfunc=lambda s: eval_zb6(s, zb6),
-            htol=htol,
-            idxsim=0,
-        ),
-        ws,
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        htol=htol,
     )
+    test.run()
diff --git a/autotest/test_gwtgwt_oldexg.py b/autotest/test_gwtgwt_oldexg.py
index 48b9ba073cf..fef038e1c5d 100644
--- a/autotest/test_gwtgwt_oldexg.py
+++ b/autotest/test_gwtgwt_oldexg.py
@@ -1,33 +1,35 @@
+"""
+Test compatibility of GWT-GWT with the 'classic' GWF exchange.
+It compares the result of a single reference model
+to the equivalent case where the domain is decomposed:
+
+       'refmodel'              'leftmodel'     'rightmodel'
+
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1    VS    1 1 1 1 1   +   1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+   1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
+
+We assert equality on the head values and the (components of)
+specific discharges. All models are part of the same solution
+for convenience. Finally, the budget error is checked.
+"""
+
 import os
 
 import flopy
 import numpy as np
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
-
-# Test compatibility of GWT-GWT with the 'classic' GWF exchange.
-# It compares the result of a single reference model
-# to the equivalent case where the domain is decomposed:
-#
-#        'refmodel'              'leftmodel'     'rightmodel'
-#
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1    VS    1 1 1 1 1   +   1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#    1 1 1 1 1 1 1 1 1 1          1 1 1 1 1       1 1 1 1 1
-#
-# We assert equality on the head values and the (components of)
-# specific discharges. All models are part of the same solution
-# for convenience. Finally, the budget error is checked.
-
-ex = ["gwtgwt_oldexg"]
+
+cases = ["gwtgwt_oldexg"]
 use_ifmod = False
 
 # some global convenience...:
@@ -87,7 +89,7 @@
 
 
 def get_model(idx, dir):
-    name = ex[idx]
+    name = cases[idx]
 
     # parameters and spd
     # tdis
@@ -554,8 +556,8 @@ def add_gwtexchange(sim):
     )
 
 
-def build_model(idx, exdir):
-    sim = get_model(idx, exdir)
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace)
     return sim, None
 
 
@@ -579,32 +581,32 @@ def qxqyqz(fname, nlay, nrow, ncol):
     return qx, qy, qz
 
 
-def compare_to_ref(sim):
-    compare_gwf_to_ref(sim)
-    compare_gwt_to_ref(sim)
+def check_output(idx, test):
+    compare_gwf_to_ref(test)
+    compare_gwt_to_ref(test)
 
 
-def compare_gwf_to_ref(sim):
+def compare_gwf_to_ref(test):
     print("comparing heads and spec. discharge to single model reference...")
 
-    fpth = os.path.join(sim.simpath, f"{mname_ref}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_ref}.hds")
     hds = flopy.utils.HeadFile(fpth)
     heads = hds.get_data()
-    fpth = os.path.join(sim.simpath, f"{mname_ref}.cbc")
+    fpth = os.path.join(test.workspace, f"{mname_ref}.cbc")
     nlay, nrow, ncol = heads.shape
     qxb, qyb, qzb = qxqyqz(fpth, nlay, nrow, ncol)
 
-    fpth = os.path.join(sim.simpath, f"{mname_left}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_left}.hds")
     hds = flopy.utils.HeadFile(fpth)
     heads_left = hds.get_data()
-    fpth = os.path.join(sim.simpath, f"{mname_left}.cbc")
+    fpth = os.path.join(test.workspace, f"{mname_left}.cbc")
     nlay, nrow, ncol = heads_left.shape
     qxb_left, qyb_left, qzb_left = qxqyqz(fpth, nlay, nrow, ncol)
 
-    fpth = os.path.join(sim.simpath, f"{mname_right}.hds")
+    fpth = os.path.join(test.workspace, f"{mname_right}.hds")
     hds = flopy.utils.HeadFile(fpth)
     heads_right = hds.get_data()
-    fpth = os.path.join(sim.simpath, f"{mname_right}.cbc")
+    fpth = os.path.join(test.workspace, f"{mname_right}.cbc")
     nlay, nrow, ncol = heads_right.shape
     qxb_right, qyb_right, qzb_right = qxqyqz(fpth, nlay, nrow, ncol)
 
@@ -675,7 +677,7 @@ def compare_gwf_to_ref(sim):
 
     # check budget error from .lst file
     for mname in [mname_ref, mname_left, mname_right]:
-        fpth = os.path.join(sim.simpath, f"{mname}.lst")
+        fpth = os.path.join(test.workspace, f"{mname}.lst")
         for line in open(fpth):
             if line.lstrip().startswith("PERCENT"):
                 cumul_balance_error = float(line.split()[3])
@@ -689,11 +691,11 @@ def compare_gwf_to_ref(sim):
     for mname in [mname_ref, mname_left, mname_right]:
         print(f"Checking flowja residual for model {mname}")
 
-        fpth = os.path.join(sim.simpath, f"{mname}.dis.grb")
+        fpth = os.path.join(test.workspace, f"{mname}.dis.grb")
         grb = flopy.mf6.utils.MfGrdFile(fpth)
         ia = grb._datadict["IA"] - 1
 
-        fpth = os.path.join(sim.simpath, f"{mname}.cbc")
+        fpth = os.path.join(test.workspace, f"{mname}.cbc")
         assert os.path.isfile(fpth)
         cbb = flopy.utils.CellBudgetFile(fpth, precision="double")
         flow_ja_face = cbb.get_data(idx=0)
@@ -708,16 +710,16 @@ def compare_gwf_to_ref(sim):
             assert np.allclose(res, 0.0, atol=1.0e-6), errmsg
 
 
-def compare_gwt_to_ref(sim):
+def compare_gwt_to_ref(test):
     print("comparing concentration  to single model reference...")
 
-    fpth = os.path.join(sim.simpath, f"{mname_gwtref}.ucn")
+    fpth = os.path.join(test.workspace, f"{mname_gwtref}.ucn")
     cnc = flopy.utils.HeadFile(fpth, text="CONCENTRATION")
     conc = cnc.get_data()
-    fpth = os.path.join(sim.simpath, f"{mname_gwtleft}.ucn")
+    fpth = os.path.join(test.workspace, f"{mname_gwtleft}.ucn")
     cnc = flopy.utils.HeadFile(fpth, text="CONCENTRATION")
     conc_left = cnc.get_data()
-    fpth = os.path.join(sim.simpath, f"{mname_gwtright}.ucn")
+    fpth = os.path.join(test.workspace, f"{mname_gwtright}.ucn")
     cnc = flopy.utils.HeadFile(fpth, text="CONCENTRATION")
     conc_right = cnc.get_data()
 
@@ -734,7 +736,7 @@ def compare_gwt_to_ref(sim):
 
     # check budget error from .lst file
     for mname in [mname_gwtref, mname_gwtleft, mname_gwtright]:
-        fpth = os.path.join(sim.simpath, f"{mname}.lst")
+        fpth = os.path.join(test.workspace, f"{mname}.lst")
         for line in open(fpth):
             if line.lstrip().startswith("PERCENT"):
                 cumul_balance_error = float(line.split()[3])
@@ -749,11 +751,11 @@ def compare_gwt_to_ref(sim):
         print(f"Checking flowja residual for model {mname}")
 
         mflowname = mname.replace("gwt", "")
-        fpth = os.path.join(sim.simpath, f"{mflowname}.dis.grb")
+        fpth = os.path.join(test.workspace, f"{mflowname}.dis.grb")
         grb = flopy.mf6.utils.MfGrdFile(fpth)
         ia = grb._datadict["IA"] - 1
 
-        fpth = os.path.join(sim.simpath, f"{mname}.cbc")
+        fpth = os.path.join(test.workspace, f"{mname}.cbc")
         assert os.path.isfile(fpth)
         cbb = flopy.utils.CellBudgetFile(fpth, precision="double")
         flow_ja_face = cbb.get_data(idx=0)
@@ -768,17 +770,13 @@ def compare_gwt_to_ref(sim):
             assert np.allclose(res, 0.0, atol=1.0e-6), errmsg
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    test = TestFramework()
-    test.build(build_model, idx, ws)
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=compare_to_ref, idxsim=idx
-        ),
-        ws,
-    )
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+    )
+    test.run()
diff --git a/autotest/test_largetestmodels.py b/autotest/test_largetestmodels.py
new file mode 100644
index 00000000000..1de7748a062
--- /dev/null
+++ b/autotest/test_largetestmodels.py
@@ -0,0 +1,36 @@
+import pytest
+
+from framework import TestFramework
+
+excluded_models = []
+
+
+@pytest.mark.large
+@pytest.mark.repo
+@pytest.mark.regression
+@pytest.mark.slow
+def test_model(
+    function_tmpdir,
+    # https://modflow-devtools.readthedocs.io/en/latest/md/fixtures.html#large-test-models
+    large_test_model,
+    markers,
+    original_regression,
+    targets,
+):
+    model_path = large_test_model.parent
+    model_name = model_path.name
+    excluded = model_name in excluded_models
+    dev_only = "dev" in model_name and "not developmode" in markers
+    if excluded or dev_only:
+        reason = "excluded" if excluded else "developmode only"
+        pytest.skip(f"Skipping: {model_name} ({reason})")
+
+    test = TestFramework(
+        name=model_name,
+        workspace=model_path,
+        targets=targets,
+        compare="auto" if original_regression else "mf6_regression",
+        verbose=False,
+    )
+    test.setup(model_path, function_tmpdir)
+    test.run()
diff --git a/autotest/test_mf6_tmp_simulations.py b/autotest/test_mf6_tmp_simulations.py
index 65600a5ab30..693680758d8 100644
--- a/autotest/test_mf6_tmp_simulations.py
+++ b/autotest/test_mf6_tmp_simulations.py
@@ -2,9 +2,9 @@
 import sys
 
 import pytest
+
 from common_regression import get_mf6_ftypes, get_namefiles
 from framework import TestFramework
-from simulation import TestSimulation
 
 exdir = os.path.join("..", "tmp_simulations")
 testpaths = os.path.join("..", exdir)
@@ -101,7 +101,6 @@ def run_mf6(sim, ws):
     appropriate MODFLOW-2005, MODFLOW-NWT, MODFLOW-USG, or MODFLOW-LGR run.
 
     """
-    print(os.getcwd())
     src = os.path.join(exdir, sim.name)
     dst = os.path.join(ws, sim.name)
     sim.setup(src, dst)
@@ -109,10 +108,11 @@ def run_mf6(sim, ws):
     sim.compare()
 
 
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(get_mf6_models())),
-)
+@pytest.mark.parametrize("idx, name", enumerate(get_mf6_models()))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ws = str(function_tmpdir)
-    run_mf6(TestSimulation(name=name, exe_dict=targets), ws)
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+    )
+    run_mf6(test, function_tmpdir)
diff --git a/autotest/test_par_gwf01.py b/autotest/test_par_gwf01.py
index 84cb1fb348b..a3c460baf4b 100644
--- a/autotest/test_par_gwf01.py
+++ b/autotest/test_par_gwf01.py
@@ -1,31 +1,37 @@
+"""
+Test for parallel MODFLOW running on two cpus.
+It contains two coupled models with
+
+1d:  (nlay,nrow,ncol) = (1,1,5),
+2d:  (nlay,nrow,ncol) = (1,5,5),
+3d:  (nlay,nrow,ncol) = (5,5,5),
+
+constant head boundaries left=1.0, right=10.0.
+The result should be a uniform flow field.
+"""
+
 import os
 
 import flopy
 import numpy as np
 import pytest
-from framework import TestFramework
-from simulation import TestSimulation
 
-# Test for parallel MODFLOW running on two cpus.
-# It contains two coupled models with 
-# 
-# 1d:  (nlay,nrow,ncol) = (1,1,5),
-# 2d:  (nlay,nrow,ncol) = (1,5,5),
-# 3d:  (nlay,nrow,ncol) = (5,5,5),
-#
-# constant head boundaries left=1.0, right=10.0.
-# The result should be a uniform flow field.
+from framework import TestFramework
 
-ex = ["par_gwf01-1d", "par_gwf01-2d", "par_gwf01-3d"]
-dis_shape = [(1,1,5), (1,5,5), (5,5,5)]
+cases = ["par_gwf01-1d", "par_gwf01-2d", "par_gwf01-3d"]
+dis_shape = [(1, 1, 5), (1, 5, 5), (5, 5, 5)]
 
 # global convenience...
 name_left = "leftmodel"
 name_right = "rightmodel"
 
-def get_model(idx, dir):
+# solver data
+nouter, ninner = 100, 300
+hclose, rclose, relax = 10e-9, 1e-3, 0.97
+
 
-    name = ex[idx]
+def get_model(idx, dir):
+    name = cases[idx]
 
     # parameters and spd
     # tdis
@@ -34,10 +40,6 @@ def get_model(idx, dir):
     for i in range(nper):
         tdis_rc.append((1.0, 1, 1))
 
-    # solver data
-    nouter, ninner = 100, 300
-    hclose, rclose, relax = 10e-9, 1e-3, 0.97
-
     # model spatial discretization
     nlay = dis_shape[idx][0]
     nrow = dis_shape[idx][1]
@@ -66,7 +68,10 @@ def get_model(idx, dir):
     h_start = 0.0
 
     sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name="mf6", sim_ws=dir,
+        sim_name=name,
+        version="mf6",
+        exe_name="mf6",
+        sim_ws=dir,
     )
 
     tdis = flopy.mf6.ModflowTdis(
@@ -78,12 +83,12 @@ def get_model(idx, dir):
         print_option="ALL",
         outer_dvclose=hclose,
         outer_maximum=nouter,
-        under_relaxation="DBD",
         inner_maximum=ninner,
         inner_dvclose=hclose,
         rcloserecord=rclose,
         linear_acceleration="BICGSTAB",
         relaxation_factor=relax,
+        pname="ims",
     )
 
     # submodel on the left:
@@ -103,7 +108,7 @@ def get_model(idx, dir):
         delr=delr,
         delc=delc,
         top=tops[0],
-        botm=tops[1:nlay+1],
+        botm=tops[1 : nlay + 1],
     )
     ic = flopy.mf6.ModflowGwfic(gwf, strt=h_start)
     npf = flopy.mf6.ModflowGwfnpf(
@@ -141,7 +146,7 @@ def get_model(idx, dir):
         xorigin=shift_x,
         yorigin=shift_y,
         top=tops[0],
-        botm=tops[1:nlay+1],
+        botm=tops[1 : nlay + 1],
     )
     ic = flopy.mf6.ModflowGwfic(gwf, strt=h_start)
     npf = flopy.mf6.ModflowGwfnpf(
@@ -184,51 +189,47 @@ def get_model(idx, dir):
         exgmnamea=name_left,
         exgmnameb=name_right,
         exchangedata=gwfgwf_data,
-        auxiliary=["ANGLDEGX", "CDIST"]
+        auxiliary=["ANGLDEGX", "CDIST"],
+        print_input=True,
     )
 
     return sim
 
-def build_petsc_db(exdir):
-    petsc_db_file = os.path.join(exdir, ".petscrc")
-    with open(petsc_db_file, 'w') as petsc_file:
-        petsc_file.write("-ksp_type cg\n")
-        petsc_file.write("-pc_type bjacobi\n")
-        petsc_file.write("-sub_pc_type ilu\n")
-        petsc_file.write("-dvclose 10e-7\n")
-        petsc_file.write("-options_left no\n")
-
-def build_model(idx, exdir):
-    sim = get_model(idx, exdir)
-    build_petsc_db(exdir)
+
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace)
     return sim, None
 
-def eval_model(sim):
+
+def check_output(idx, test):
     # two coupled models with a uniform flow field,
-    # here we assert the known head values at the 
+    # here we assert the known head values at the
     # cell centers
-    fpth = os.path.join(sim.simpath, f"{name_left}.hds")
+    fpth = os.path.join(test.workspace, f"{name_left}.hds")
     hds = flopy.utils.HeadFile(fpth)
     heads_left = hds.get_data().flatten()
-    fpth = os.path.join(sim.simpath, f"{name_right}.hds")
+    fpth = os.path.join(test.workspace, f"{name_right}.hds")
     hds = flopy.utils.HeadFile(fpth)
     heads_right = hds.get_data().flatten()
-    np.testing.assert_array_almost_equal(heads_left[0:5], [1.0, 2.0, 3.0, 4.0, 5.0])
-    np.testing.assert_array_almost_equal(heads_right[0:5], [6.0, 7.0, 8.0, 9.0, 10.0])
+    np.testing.assert_array_almost_equal(
+        heads_left[0:5], [1.0, 2.0, 3.0, 4.0, 5.0]
+    )
+    np.testing.assert_array_almost_equal(
+        heads_right[0:5], [6.0, 7.0, 8.0, 9.0, 10.0]
+    )
+
 
 @pytest.mark.parallel
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, 
-            idxsim=0, make_comparison=False,
-            parallel=True, ncpus=2,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+        parallel=True,
+        ncpus=2,
     )
+    test.run()
diff --git a/autotest/test_par_gwf02.py b/autotest/test_par_gwf02.py
index d8681868dae..70ffd2f298d 100644
--- a/autotest/test_par_gwf02.py
+++ b/autotest/test_par_gwf02.py
@@ -1,31 +1,37 @@
-import os
+"""
+Test for parallel MODFLOW running a simple
+multi-model setup with different numbers 
+of partitions 
+
+
+   [M1ny] |  ...  |   ...  | [Mnxny]
+  -----------------------------------
+     ...  |  ...  |   ...  |   ...
+  -----------------------------------
+    [M12] |  ...  |   ...  |   ...
+  -----------------------------------
+    [M11] | [M21] |   ...  | [Mnx1]
+
+with constant head set at the lower-left corner.
+This constant head should reach all domains,
+no matter the topology of partitions
+"""
 
 import flopy
 import numpy as np
-from decimal import Decimal
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
-
-# Test for parallel MODFLOW running a simple
-# multi-model setup on different partitionings 
-# 
-#
-#    [M1ny] |  ...  |   ...  | [Mnxny]
-#   -----------------------------------
-#      ...  |  ...  |   ...  |   ...
-#   -----------------------------------
-#     [M12] |  ...  |   ...  |   ...
-#   -----------------------------------
-#     [M11] | [M21] |   ...  | [Mnx1]
-# 
-# with constant head set at the lower-left corner.
-# This constant head should reach all domains,
-# no matter the topology of partitions
-
-ex = ["par_gwf02-a", "par_gwf02-b", "par_gwf02-c", 
-      "par_gwf02-d", "par_gwf02-e", "par_gwf02-f"]
-domain_grid = [(1,5), (5,1), (2,2), (3,3), (4,4), (5,5)]
+
+cases = [
+    "par_gwf02-a",
+    "par_gwf02-b",
+    "par_gwf02-c",
+    "par_gwf02-d",
+    "par_gwf02-e",
+    "par_gwf02-f",
+]
+domain_grid = [(1, 5), (5, 1), (2, 2), (3, 3), (4, 4), (5, 5)]
 
 nlay = 1
 nrow = 3
@@ -41,9 +47,8 @@ def get_model_name(ix, iy):
     return f"model-{ix}-{iy}"
 
 
-def get_simulation(idx, dir):
-
-    name = ex[idx]
+def get_simulation(idx, ws):
+    name = cases[idx]
     nr_models_x = domain_grid[idx][0]
     nr_models_y = domain_grid[idx][1]
 
@@ -59,7 +64,10 @@ def get_simulation(idx, dir):
     rclose, relax = 1e-3, 0.97
 
     sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name="mf6", sim_ws=dir,
+        sim_name=name,
+        version="mf6",
+        exe_name="mf6",
+        sim_ws=ws,
     )
 
     tdis = flopy.mf6.ModflowTdis(
@@ -90,18 +98,18 @@ def get_simulation(idx, dir):
             name_west = get_model_name(ix, iy)
             name_east = get_model_name(ix + 1, iy)
             add_exchange_west_east(sim, name_west, name_east)
-    
+
     # add exchange from south to north
     for ix in range(nr_models_x):
-        for iy in range(nr_models_y -1 ):
+        for iy in range(nr_models_y - 1):
             name_south = get_model_name(ix, iy)
             name_north = get_model_name(ix, iy + 1)
             add_exchange_south_north(sim, name_south, name_north)
 
     return sim
 
-def add_model(sim, ix, iy, nr_models_x, nr_models_y):
 
+def add_model(sim, ix, iy, nr_models_x, nr_models_y):
     # model spatial discretization
     shift_x = ix * ncol * delr
     shift_y = iy * nrow * delc
@@ -125,9 +133,9 @@ def add_model(sim, ix, iy, nr_models_x, nr_models_y):
         delr=delr,
         delc=delc,
         top=tops[0],
-        botm=tops[1:nlay+1],
+        botm=tops[1 : nlay + 1],
         xorigin=shift_x,
-        yorigin=shift_y
+        yorigin=shift_y,
     )
     ic = flopy.mf6.ModflowGwfic(gwf, strt=h_start)
     npf = flopy.mf6.ModflowGwfnpf(
@@ -151,8 +159,8 @@ def add_model(sim, ix, iy, nr_models_x, nr_models_y):
         chd_spd_sw = {0: sw_chd}
         chd = flopy.mf6.ModflowGwfchd(gwf, stress_period_data=chd_spd_sw)
 
-def add_exchange_west_east(sim, name_west, name_east):
 
+def add_exchange_west_east(sim, name_west, name_east):
     exg_filename = f"we_{name_west}_{name_east}.gwfgwf"
     # exchangedata
     angldegx = 0.0
@@ -179,11 +187,11 @@ def add_exchange_west_east(sim, name_west, name_east):
         exgmnameb=name_east,
         exchangedata=gwfgwf_data,
         auxiliary=["ANGLDEGX", "CDIST"],
-        filename=exg_filename
+        filename=exg_filename,
     )
 
-def add_exchange_south_north(sim, name_south, name_north):
 
+def add_exchange_south_north(sim, name_south, name_north):
     exg_filename = f"sn_{name_south}_{name_north}.gwfgwf"
 
     # exchangedata
@@ -192,7 +200,7 @@ def add_exchange_south_north(sim, name_south, name_north):
     gwfgwf_data = [
         [
             (ilay, 0, icol),
-            (ilay, nrow-1, icol),
+            (ilay, nrow - 1, icol),
             1,
             delc / 2.0,
             delc / 2.0,
@@ -211,46 +219,36 @@ def add_exchange_south_north(sim, name_south, name_north):
         exgmnameb=name_north,
         exchangedata=gwfgwf_data,
         auxiliary=["ANGLDEGX", "CDIST"],
-        filename=exg_filename
+        filename=exg_filename,
     )
 
-def build_petsc_db(exdir):
-    petsc_db_file = os.path.join(exdir, ".petscrc")
-    with open(petsc_db_file, 'w') as petsc_file:
-        petsc_file.write("-ksp_type cg\n")
-        petsc_file.write("-pc_type bjacobi\n")
-        petsc_file.write("-sub_pc_type ilu\n")
-        petsc_file.write(f"-dvclose {Decimal(hclose):.2E}\n")
-        petsc_file.write("-options_left no\n")
-
-def build_model(idx, exdir):
-    sim = get_simulation(idx, exdir)
-    build_petsc_db(exdir)
+
+def build_models(idx, test):
+    sim = get_simulation(idx, test.workspace)
     return sim, None
 
-def eval_model(sim):
-    mf6_sim = flopy.mf6.MFSimulation.load(sim_ws=sim.simpath)
+
+def check_output(idx, test):
+    mf6_sim = flopy.mf6.MFSimulation.load(sim_ws=test.workspace)
     for mname in mf6_sim.model_names:
         m = mf6_sim.get_model(mname)
         hds = m.output.head().get_data().flatten()
-        hds_compare = cst_head_south_west*np.ones_like(hds)
+        hds_compare = cst_head_south_west * np.ones_like(hds)
         assert np.allclose(hds, hds_compare, atol=1.0e-6, rtol=0.0)
-    
+
 
 @pytest.mark.parallel
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    ncpus = domain_grid[idx][0]*domain_grid[idx][1]
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, 
-            idxsim=0, make_comparison=False,
-            parallel=True, ncpus=ncpus,
-        ),
-        str(function_tmpdir),
+    ncpus = domain_grid[idx][0] * domain_grid[idx][1]
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+        parallel=True,
+        ncpus=ncpus,
     )
+    test.run()
diff --git a/autotest/test_par_gwf03.py b/autotest/test_par_gwf03.py
index 2d329446a14..77d09a1ca8a 100644
--- a/autotest/test_par_gwf03.py
+++ b/autotest/test_par_gwf03.py
@@ -1,31 +1,29 @@
-import os
+"""
+Scaling parallel MODFLOW running a simple
+(multi-)model setup on different partitionings
+with constant head set at the lower-left corner.
+
+a: 1 cpus, 1 model
+b: 1 cpus, 4 models
+c: 2 cpus, 4 models
+d: 4 cpus, 4 models
+
+The test is that for all configurations, the head
+converges globally to the specified boundary value.
+In general, the test can be used to compare parallel
+vs. serial behavior on an identical problem.
+"""
 
 import flopy
 import numpy as np
-from decimal import Decimal
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
-
-# Scaling parallel MODFLOW running a simple
-# (multi-)model setup on different partitionings
-# with constant head set at the lower-left corner.
-#
-# a: 1 cpus, 1 model
-# b: 1 cpus, 4 models
-# c: 2 cpus, 4 models
-# d: 4 cpus, 4 models
-#
-# The test is that for all configurations, the head
-# converges globally to the specified boundary value.
-# In general, the test can be used to compare parallel
-# vs. serial behavior on an identical problem.
-
-ex = ["par_gwf03-a", "par_gwf03-b", "par_gwf03-c", "par_gwf03-d"]
+
+cases = ["par_gwf03-a", "par_gwf03-b", "par_gwf03-c", "par_gwf03-d"]
 ncpus = [1, 1, 2, 4]
 domain_grid = [(1, 1), (2, 2), (2, 2), (2, 2)]
 dis_shape = [(2, 100, 100), (2, 50, 50), (2, 50, 50), (2, 50, 50)]
-
 delr = 100.0
 delc = 100.0
 head_initial = -1.0
@@ -37,9 +35,8 @@ def get_model_name(ix, iy):
     return f"model-{ix}-{iy}"
 
 
-def get_simulation(idx, dir):
-
-    name = ex[idx]
+def get_simulation(idx, ws):
+    name = cases[idx]
     nr_models_x = domain_grid[idx][0]
     nr_models_y = domain_grid[idx][1]
 
@@ -51,7 +48,7 @@ def get_simulation(idx, dir):
     # tdis
     nper = 1
     tdis_rc = []
-    for i in range(nper):
+    for _ in range(nper):
         tdis_rc.append((1.0, 1, 1))
 
     # solver data
@@ -59,7 +56,10 @@ def get_simulation(idx, dir):
     rclose, relax = 1e-3, 0.97
 
     sim = flopy.mf6.MFSimulation(
-        sim_name=name, version="mf6", exe_name="mf6", sim_ws=dir,
+        sim_name=name,
+        version="mf6",
+        exe_name="mf6",
+        sim_ws=ws,
     )
 
     tdis = flopy.mf6.ModflowTdis(
@@ -75,7 +75,7 @@ def get_simulation(idx, dir):
         inner_dvclose=hclose,
         rcloserecord=rclose,
         linear_acceleration="CG",
-        relaxation_factor=0.0, # turn this off for comparison
+        relaxation_factor=0.0,  # turn this off for comparison
     )
 
     # create models (and exchanges)
@@ -89,25 +89,27 @@ def get_simulation(idx, dir):
             name_west = get_model_name(ix, iy)
             name_east = get_model_name(ix + 1, iy)
             add_exchange_west_east(sim, name_west, name_east, nlay, nrow, ncol)
-    
+
     # add exchange from south to north
     for ix in range(nr_models_x):
-        for iy in range(nr_models_y -1 ):
+        for iy in range(nr_models_y - 1):
             name_south = get_model_name(ix, iy)
             name_north = get_model_name(ix, iy + 1)
-            add_exchange_south_north(sim, name_south, name_north, nlay, nrow, ncol)
+            add_exchange_south_north(
+                sim, name_south, name_north, nlay, nrow, ncol
+            )
 
     return sim
 
-def add_model(sim, ix, iy, nr_models_x, nr_models_y, nlay, nrow, ncol):
 
+def add_model(sim, ix, iy, nr_models_x, nr_models_y, nlay, nrow, ncol):
     # model spatial discretization
     shift_x = ix * ncol * delr
     shift_y = iy * nrow * delc
     model_name = get_model_name(ix, iy)
 
     # top/bot of the aquifer
-    tops = [-100.0*i for i in range(nlay + 1)]
+    tops = [-100.0 * i for i in range(nlay + 1)]
 
     # hydraulic conductivity
     k11 = 10.0
@@ -124,9 +126,9 @@ def add_model(sim, ix, iy, nr_models_x, nr_models_y, nlay, nrow, ncol):
         delr=delr,
         delc=delc,
         top=tops[0],
-        botm=tops[1:nlay+1],
+        botm=tops[1 : nlay + 1],
         xorigin=shift_x,
-        yorigin=shift_y
+        yorigin=shift_y,
     )
     ic = flopy.mf6.ModflowGwfic(gwf, strt=h_start)
     npf = flopy.mf6.ModflowGwfnpf(
@@ -150,8 +152,8 @@ def add_model(sim, ix, iy, nr_models_x, nr_models_y, nlay, nrow, ncol):
         chd_spd_sw = {0: sw_chd}
         chd = flopy.mf6.ModflowGwfchd(gwf, stress_period_data=chd_spd_sw)
 
-def add_exchange_west_east(sim, name_west, name_east, nlay, nrow, ncol):
 
+def add_exchange_west_east(sim, name_west, name_east, nlay, nrow, ncol):
     exg_filename = f"we_{name_west}_{name_east}.gwfgwf"
     # exchangedata
     angldegx = 0.0
@@ -178,11 +180,11 @@ def add_exchange_west_east(sim, name_west, name_east, nlay, nrow, ncol):
         exgmnameb=name_east,
         exchangedata=gwfgwf_data,
         auxiliary=["ANGLDEGX", "CDIST"],
-        filename=exg_filename
+        filename=exg_filename,
     )
 
-def add_exchange_south_north(sim, name_south, name_north, nlay, nrow, ncol):
 
+def add_exchange_south_north(sim, name_south, name_north, nlay, nrow, ncol):
     exg_filename = f"sn_{name_south}_{name_north}.gwfgwf"
 
     # exchangedata
@@ -191,7 +193,7 @@ def add_exchange_south_north(sim, name_south, name_north, nlay, nrow, ncol):
     gwfgwf_data = [
         [
             (ilay, 0, icol),
-            (ilay, nrow-1, icol),
+            (ilay, nrow - 1, icol),
             1,
             delc / 2.0,
             delc / 2.0,
@@ -210,49 +212,35 @@ def add_exchange_south_north(sim, name_south, name_north, nlay, nrow, ncol):
         exgmnameb=name_north,
         exchangedata=gwfgwf_data,
         auxiliary=["ANGLDEGX", "CDIST"],
-        filename=exg_filename
+        filename=exg_filename,
     )
 
-def build_petsc_db(idx, exdir):
-    np = ncpus[idx]
-    petsc_db_file = os.path.join(exdir, ".petscrc")
-    with open(petsc_db_file, 'w') as petsc_file:
-        petsc_file.write("-ksp_type cg\n")
-        petsc_file.write("-pc_type bjacobi\n")
-        petsc_file.write("-sub_pc_type ilu\n")
-        petsc_file.write("-sub_pc_factor_levels 2\n")
-        petsc_file.write(f"-dvclose {Decimal(hclose):.2E}\n")
-        petsc_file.write(f"-nitermax {500}\n")
-        petsc_file.write("-options_left no\n")
-
-def build_model(idx, exdir):
-    sim = get_simulation(idx, exdir)
-    build_petsc_db(idx, exdir)
+
+def build_models(idx, test):
+    sim = get_simulation(idx, test.workspace)
     return sim, None
 
-def eval_model(sim):
-    mf6_sim = flopy.mf6.MFSimulation.load(sim_ws=sim.simpath)
+
+def check_output(idx, test):
+    mf6_sim = flopy.mf6.MFSimulation.load(sim_ws=test.workspace)
     for mname in mf6_sim.model_names:
         m = mf6_sim.get_model(mname)
         hds = m.output.head().get_data().flatten()
-        hds_compare = cst_head_south_west*np.ones_like(hds)
+        hds_compare = cst_head_south_west * np.ones_like(hds)
         assert np.allclose(hds, hds_compare, rtol=1.0e-6, atol=0.0001)
-    
+
 
 @pytest.mark.parallel
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    np = ncpus[idx]
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, 
-            idxsim=0, make_comparison=False,
-            parallel=True, ncpus=np,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+        parallel=True,
+        ncpus=ncpus[idx],
     )
+    test.run()
diff --git a/autotest/test_par_gwf_disu.py b/autotest/test_par_gwf_disu.py
new file mode 100644
index 00000000000..da77695e6c2
--- /dev/null
+++ b/autotest/test_par_gwf_disu.py
@@ -0,0 +1,238 @@
+"""
+Test for parallel MODFLOW running on two cpus.
+Each case contains two coupled DISU models which are
+generated from their DIS counterparts:
+
+1d:  (nlay,nrow,ncol) = (1,1,5),
+2d:  (nlay,nrow,ncol) = (1,5,5),
+3d:  (nlay,nrow,ncol) = (5,5,5),
+
+constant head boundaries left=1.0, right=10.0.
+The result should be a uniform flow field.
+"""
+
+import os
+
+import flopy
+import numpy as np
+import pytest
+from flopy.utils.gridutil import get_disu_kwargs
+
+from framework import TestFramework
+
+cases = [
+    "par_gwf_disu1d",
+    "par_gwf_disu2d",
+    "par_gwf_disu3d",
+]
+dis_shape = [(1, 1, 5), (1, 1, 5), (1, 1, 5), (1, 5, 5), (5, 5, 5)]
+
+# global convenience...
+name_left = "leftmodel"
+name_right = "rightmodel"
+
+# solver data
+nouter, ninner = 100, 300
+hclose, rclose, relax = 10e-9, 1e-3, 0.97
+
+
+def get_model(idx, dir):
+    name = cases[idx]
+
+    # parameters and spd
+    # tdis
+    nper = 1
+    tdis_rc = []
+    for i in range(nper):
+        tdis_rc.append((1.0, 1, 1))
+
+    # model spatial discretization
+    nlay = dis_shape[idx][0]
+    nrow = dis_shape[idx][1]
+    ncol = dis_shape[idx][2]
+
+    # cell spacing
+    delr = 100.0
+    delr_arr = delr * np.ones(ncol)
+    delc = 100.0
+    delc_arr = delc * np.ones(nrow)
+
+    # shift
+    shift_x = 5 * delr
+    shift_y = 0.0
+
+    # top/bot of the aquifer
+    tops = [0.0, -100.0, -200.0, -300.0, -400.0, -500.0]
+
+    # conversion to DISU
+    disukwargs = get_disu_kwargs(
+        nlay,
+        nrow,
+        ncol,
+        delr_arr,
+        delc_arr,
+        tops[0],
+        tops[1 : nlay + 1],
+        return_vertices=True,
+    )
+
+    # hydraulic conductivity
+    k11 = 1.0
+
+    # boundary stress period data
+    h_left = 1.0
+    h_right = 10.0
+
+    # initial head
+    h_start = 0.0
+
+    sim = flopy.mf6.MFSimulation(
+        sim_name=name,
+        version="mf6",
+        exe_name="mf6",
+        sim_ws=dir,
+    )
+
+    tdis = flopy.mf6.ModflowTdis(
+        sim, time_units="DAYS", nper=nper, perioddata=tdis_rc
+    )
+
+    ims = flopy.mf6.ModflowIms(
+        sim,
+        print_option="ALL",
+        outer_dvclose=hclose,
+        outer_maximum=nouter,
+        inner_maximum=ninner,
+        inner_dvclose=hclose,
+        rcloserecord=rclose,
+        linear_acceleration="BICGSTAB",
+        relaxation_factor=relax,
+        pname="ims",
+    )
+
+    # submodel on the left:
+    left_chd = [
+        [(ilay * ncol * nrow + irow * ncol), h_left]
+        for irow in range(nrow)
+        for ilay in range(nlay)
+    ]
+    chd_spd_left = {0: left_chd}
+
+    gwf = flopy.mf6.ModflowGwf(sim, modelname=name_left, save_flows=True)
+    disu = flopy.mf6.ModflowGwfdisu(gwf, **disukwargs)
+    ic = flopy.mf6.ModflowGwfic(gwf, strt=h_start)
+    npf = flopy.mf6.ModflowGwfnpf(
+        gwf,
+        save_specific_discharge=False,  # let's skip angledegx
+        save_flows=True,
+        icelltype=0,
+        k=k11,
+    )
+    chd = flopy.mf6.ModflowGwfchd(gwf, stress_period_data=chd_spd_left)
+    oc = flopy.mf6.ModflowGwfoc(
+        gwf,
+        head_filerecord=f"{name_left}.hds",
+        budget_filerecord=f"{name_left}.cbc",
+        headprintrecord=[("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")],
+        saverecord=[("HEAD", "LAST"), ("BUDGET", "LAST")],
+    )
+
+    # submodel on the right:
+    right_chd = [
+        [(ilay * ncol * nrow + irow * ncol + ncol - 1), h_right]
+        for irow in range(nrow)
+        for ilay in range(nlay)
+    ]
+    chd_spd_right = {0: right_chd}
+
+    gwf = flopy.mf6.ModflowGwf(sim, modelname=name_right, save_flows=True)
+    disukwargs["xorigin"] = shift_x
+    disukwargs["yorigin"] = shift_y
+    disu = flopy.mf6.ModflowGwfdisu(gwf, **disukwargs)
+    ic = flopy.mf6.ModflowGwfic(gwf, strt=h_start)
+    npf = flopy.mf6.ModflowGwfnpf(
+        gwf,
+        save_specific_discharge=False,  # let's skip angledegx
+        save_flows=True,
+        icelltype=0,
+        k=k11,
+    )
+    chd = flopy.mf6.ModflowGwfchd(gwf, stress_period_data=chd_spd_right)
+    oc = flopy.mf6.ModflowGwfoc(
+        gwf,
+        head_filerecord=f"{name_right}.hds",
+        budget_filerecord=f"{name_right}.cbc",
+        headprintrecord=[("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")],
+        saverecord=[("HEAD", "LAST"), ("BUDGET", "LAST")],
+    )
+
+    # exchangedata
+    angldegx = 0.0
+    cdist = delr
+    gwfgwf_data = [
+        [
+            (ilay * ncol * nrow + irow * ncol + ncol - 1),
+            (ilay * ncol * nrow + irow * ncol),
+            1,
+            delr / 2.0,
+            delr / 2.0,
+            delc,
+            angldegx,
+            cdist,
+        ]
+        for irow in range(nrow)
+        for ilay in range(nlay)
+    ]
+
+    gwfgwf = flopy.mf6.ModflowGwfgwf(
+        sim,
+        exgtype="GWF6-GWF6",
+        nexg=len(gwfgwf_data),
+        exgmnamea=name_left,
+        exgmnameb=name_right,
+        exchangedata=gwfgwf_data,
+        auxiliary=["ANGLDEGX", "CDIST"],
+        print_input=True,
+    )
+
+    return sim
+
+
+def build_models(idx, test):
+    sim = get_model(idx, test.workspace)
+    return sim, None
+
+
+def check_output(idx, test):
+    pass
+    # two coupled models with a uniform flow field,
+    # here we assert the known head values at the
+    # cell centers
+    fpth = os.path.join(test.workspace, f"{name_left}.hds")
+    hds = flopy.utils.HeadFile(fpth)
+    heads_left = hds.get_data().flatten()
+    fpth = os.path.join(test.workspace, f"{name_right}.hds")
+    hds = flopy.utils.HeadFile(fpth)
+    heads_right = hds.get_data().flatten()
+    np.testing.assert_array_almost_equal(
+        heads_left[0:5], [1.0, 2.0, 3.0, 4.0, 5.0]
+    )
+    np.testing.assert_array_almost_equal(
+        heads_right[0:5], [6.0, 7.0, 8.0, 9.0, 10.0]
+    )
+
+
+@pytest.mark.parallel
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+        parallel=True,
+        ncpus=2,
+    )
+    test.run()
diff --git a/autotest/test_par_gwf_exgmvr01.py b/autotest/test_par_gwf_exgmvr01.py
new file mode 100644
index 00000000000..61783322d68
--- /dev/null
+++ b/autotest/test_par_gwf_exgmvr01.py
@@ -0,0 +1,45 @@
+"""
+This tests reuses the simulation data in test_gwf_exgmvr01.py
+and runs it in parallel on two cpus with
+
+cpu 1: 'left'
+cpu 2: 'right'
+
+so we can compare the parallel coupling of 'left' + 'right'
+with a serial 'single'
+"""
+
+import pytest
+
+from framework import TestFramework
+
+cases = ["par_exgmvr01"]
+
+
+def build_models(idx, test):
+    from test_gwf_exgmvr01 import build_models as build
+
+    sim, sim_ref = build(idx, test)
+    return sim, sim_ref
+
+
+def check_output(idx, test):
+    from test_gwf_exgmvr01 import check_output as check
+
+    check(idx, test)
+
+
+@pytest.mark.parallel
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        parallel=True,
+        ncpus=(2, 1),
+        compare=None,
+    )
+    test.run()
diff --git a/autotest/test_par_gwf_exgmvr02.py b/autotest/test_par_gwf_exgmvr02.py
new file mode 100644
index 00000000000..2f222b8cbba
--- /dev/null
+++ b/autotest/test_par_gwf_exgmvr02.py
@@ -0,0 +1,45 @@
+"""
+This tests reuses the simulation data in test_gwf_exgmvr02.py
+and runs it in parallel on two cpus with
+
+cpu 1: 'left'
+cpu 2: 'right'
+
+so we can compare the parallel coupling of 'left' + 'right'
+with a serial 'single'
+"""
+
+import pytest
+
+from framework import TestFramework
+
+cases = ["par_exgmvr02"]
+
+
+def build_models(idx, test):
+    from test_gwf_exgmvr02 import build_models as build
+
+    sim, sim_ref = build(idx, test)
+    return sim, sim_ref
+
+
+def check_output(idx, test):
+    from test_gwf_exgmvr02 import check_output as check
+
+    check(idx, test)
+
+
+@pytest.mark.parallel
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        parallel=True,
+        ncpus=(2, 1),
+        compare=None,
+    )
+    test.run()
diff --git a/autotest/test_par_gwf_idomain.py b/autotest/test_par_gwf_idomain.py
index f471d0bf2f0..ce1ae2b0c7a 100644
--- a/autotest/test_par_gwf_idomain.py
+++ b/autotest/test_par_gwf_idomain.py
@@ -1,56 +1,46 @@
-import os
-from decimal import Decimal
+"""
+This tests reuses the simulation data in test_gwf_ifmod_idomain.py
+and runs it in parallel on three cpus with
+
+cpu 0: 'refmodel'
+cpu 1: 'leftmodel'
+cpu 2: 'rightmodel'
+
+so we can compare the parallel coupling of 'leftmodel' + 'rightmodel'
+with a serial 'refmodel'
+"""
+
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
-
-# This tests reuses the simulation data in test_gwf_ifmod_idomain.py
-# and runs it in parallel on three cpus with
-#
-# cpu 0: 'refmodel'
-# cpu 1: 'leftmodel'
-# cpu 2: 'rightmodel'
-#
-# so we can compare the parallel coupling of 'leftmodel' + 'rightmodel'
-# with a serial 'refmodel'
-
-ex = ["par_idomain"]
-
-def build_petsc_db(idx, exdir):
-    from test_gwf_ifmod_idomain import hclose_check, max_inner_it
-    petsc_db_file = os.path.join(exdir, ".petscrc")
-    with open(petsc_db_file, 'w') as petsc_file:
-        petsc_file.write("-ksp_type bicg\n")
-        petsc_file.write("-pc_type bjacobi\n")
-        petsc_file.write("-sub_pc_type ilu\n")
-        petsc_file.write("-sub_pc_factor_levels 2\n")
-        petsc_file.write(f"-dvclose {Decimal(hclose_check):.2E}\n")
-        petsc_file.write(f"-nitermax {max_inner_it}\n")
-        petsc_file.write("-options_left no\n")
-
-def build_model(idx, exdir):
-    from test_gwf_ifmod_idomain import build_model as build_model_ext
-    build_petsc_db(idx, exdir)
-    sim, dummy = build_model_ext(idx, exdir)
+
+cases = ["par_idomain"]
+
+
+def build_models(idx, test):
+    from test_gwf_ifmod_idomain import build_models as build
+
+    sim, dummy = build(idx, test)
     return sim, dummy
 
-def eval_model(test_sim):
-    from test_gwf_ifmod_idomain import compare_to_ref
-    compare_to_ref(test_sim)    
+
+def check_output(idx, test):
+    from test_gwf_ifmod_idomain import check_output as check
+
+    check(idx, test)
+
 
 @pytest.mark.parallel
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, 
-            idxsim=0, make_comparison=False,
-            parallel=True, ncpus=3,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+        parallel=True,
+        ncpus=3,
     )
+    test.run()
diff --git a/autotest/test_par_gwf_ims_csv.py b/autotest/test_par_gwf_ims_csv.py
new file mode 100644
index 00000000000..0b400b2645d
--- /dev/null
+++ b/autotest/test_par_gwf_ims_csv.py
@@ -0,0 +1,61 @@
+import flopy
+import pytest
+
+from framework import TestFramework
+
+"""
+Test for parallel MODFLOW running on two cpus.
+It contains two coupled models with
+
+1d:  (nlay,nrow,ncol) = (1,1,5),
+
+constant head boundaries left=1.0, right=10.0.
+The result should be a uniform flow field.
+"""
+
+cases = ["par_gwf_csv"]
+dis_shape = [(1, 1, 5)]
+
+# global convenience...
+name_left = "leftmodel"
+name_right = "rightmodel"
+
+
+def update_ims(idx, ims):
+    from test_par_gwf01 import hclose, ninner, nouter, rclose
+
+    name = cases[idx]
+    ims.csv_outer_output_filerecord.set_data(f"{name}.outer.csv")
+    ims.csv_inner_output_filerecord.set_data(f"{name}.inner.csv")
+    return
+
+
+def build_models(idx, test):
+    from test_par_gwf01 import cases as ex_ext
+    from test_par_gwf01 import get_model
+
+    sim = get_model(idx, test.workspace)
+    update_ims(idx, sim.get_solution_package(f"{ex_ext[idx]}.ims"))
+    return sim, None
+
+
+def check_output(idx, test):
+    from test_par_gwf01 import check_output as check
+
+    check(idx, test)
+
+
+@pytest.mark.parallel
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+        parallel=True,
+        ncpus=2,
+    )
+    test.run()
diff --git a/autotest/test_par_gwf_newton.py b/autotest/test_par_gwf_newton.py
index 29881e3cccb..d8e61ccb5d9 100644
--- a/autotest/test_par_gwf_newton.py
+++ b/autotest/test_par_gwf_newton.py
@@ -1,58 +1,48 @@
-import os
-from decimal import Decimal
+"""
+This tests reuses the simulation data in test_gwf_ifmod_newton.py
+and runs it in parallel on three cpus with
+
+cpu 0: 'refmodel'
+cpu 1: 'leftmodel'
+cpu 2: 'rightmodel'
+
+so we can compare the parallel coupling of 'leftmodel' + 'rightmodel'
+with a serial 'refmodel'.
+
+This test also checks that PTC works in parallel.
+"""
+
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
-
-# This tests reuses the simulation data in test_gwf_ifmod_newton.py
-# and runs it in parallel on three cpus with
-#
-# cpu 0: 'refmodel'
-# cpu 1: 'leftmodel'
-# cpu 2: 'rightmodel'
-#
-# so we can compare the parallel coupling of 'leftmodel' + 'rightmodel'
-# with a serial 'refmodel'.
-#
-# This test also checks that PTC works in parallel.
-
-ex = ["par_newton"]
-
-def build_petsc_db(idx, exdir):
-    from test_gwf_ifmod_newton import hclose_check, max_inner_it
-    petsc_db_file = os.path.join(exdir, ".petscrc")
-    with open(petsc_db_file, 'w') as petsc_file:
-        petsc_file.write("-ksp_type bicg\n")
-        petsc_file.write("-pc_type bjacobi\n")
-        petsc_file.write("-sub_pc_type ilu\n")
-        petsc_file.write("-sub_pc_factor_levels 2\n")
-        petsc_file.write(f"-dvclose {Decimal(hclose_check):.2E}\n")
-        petsc_file.write(f"-nitermax {max_inner_it}\n")
-        petsc_file.write("-options_left no\n")
-
-def build_model(idx, exdir):
-    from test_gwf_ifmod_newton import build_model as build_model_ext
-    build_petsc_db(idx, exdir)
-    sim, dummy = build_model_ext(idx, exdir)
+
+cases = ["par_newton"]
+
+
+def build_models(idx, test):
+    from test_gwf_ifmod_newton import build_models as build
+
+    sim, dummy = build(idx, test)
     return sim, dummy
 
-def eval_model(test_sim):
-    from test_gwf_ifmod_newton import compare_to_ref
-    compare_to_ref(test_sim)    
+
+def check_output(idx, test):
+    from test_gwf_ifmod_newton import check_output as check
+
+    check(idx, test)
+
 
 @pytest.mark.parallel
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, 
-            idxsim=0, make_comparison=False,
-            parallel=True, ncpus=3,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+        parallel=True,
+        ncpus=3,
     )
+    test.run()
diff --git a/autotest/test_par_gwf_newton_under_relaxation.py b/autotest/test_par_gwf_newton_under_relaxation.py
new file mode 100644
index 00000000000..628a4f0c107
--- /dev/null
+++ b/autotest/test_par_gwf_newton_under_relaxation.py
@@ -0,0 +1,63 @@
+"""
+This tests reuses the simulation data in test_gwf_newton_under_relaxation
+and runs it in parallel on one and two cpus with
+
+so we can compare the parallel coupling of two models
+with a serial model.
+
+This test also checks that Newton under_relaxation works in parallel.
+"""
+
+import os
+from decimal import Decimal
+
+import pytest
+
+from framework import TestFramework
+
+cases = ["par_nr_ur01", "par_nr_ur02"]
+
+
+def build_petsc_db(idx, exdir):
+    from test_gwf_newton_under_relaxation import hclose, ninner
+
+    petsc_db_file = os.path.join(exdir, ".petscrc")
+    with open(petsc_db_file, "w") as petsc_file:
+        petsc_file.write("-ksp_type bicg\n")
+        petsc_file.write("-pc_type bjacobi\n")
+        petsc_file.write("-sub_pc_type ilu\n")
+        petsc_file.write("-sub_pc_factor_levels 2\n")
+        petsc_file.write(f"-dvclose {Decimal(hclose):.2E}\n")
+        petsc_file.write(f"-nitermax {ninner}\n")
+        petsc_file.write("-options_left no\n")
+
+
+def build_models(idx, test):
+    from test_gwf_newton_under_relaxation import build_models as build
+
+    build_petsc_db(idx, test.workspace)
+    sim, dummy = build(idx, test)
+    return sim, dummy
+
+
+def check_output(idx, test):
+    from test_gwf_newton_under_relaxation import check_output as check
+
+    check(idx, test)
+
+
+@pytest.mark.parallel
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    ncpus = 2 if idx == 1 else 1
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+        parallel=True,
+        ncpus=ncpus,
+    )
+    test.run()
diff --git a/autotest/test_par_gwf_pakcc.py b/autotest/test_par_gwf_pakcc.py
new file mode 100644
index 00000000000..8064f1421f7
--- /dev/null
+++ b/autotest/test_par_gwf_pakcc.py
@@ -0,0 +1,53 @@
+"""
+This tests reuses the simulation data in test_gwf_uzf_gwet
+and runs it in parallel on one and two cpus with
+
+so we can compare the parallel coupling of two models
+with a serial model.
+
+This test also checks that Newton under_relaxation works in parallel.
+"""
+
+import pathlib as pl
+
+import flopy
+import numpy as np
+import pytest
+
+from framework import TestFramework
+
+cases = ["par_uzf_3lay_1p", "par_uzf_3lay_2p"]
+
+
+def build_models(idx, test):
+    from test_gwf_uzf_gwet import build_models as build
+
+    sim, dummy = build(idx, test)
+    if idx == 1:
+        sim.set_sim_path(test.workspace / "working")
+        sim.write_simulation(silent=True)
+        mfsplit = flopy.mf6.utils.Mf6Splitter(sim)
+        split_array = np.zeros((10), dtype=int)
+        split_array[5:] = 1
+        new_sim = mfsplit.split_model(split_array)
+        new_sim.set_sim_path(test.workspace)
+        mfsplit.save_node_mapping(pl.Path(f"{test.workspace}/mapping.json"))
+        return new_sim, None
+    else:
+        return sim, dummy
+
+
+@pytest.mark.parallel
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    ncpus = 2 if idx == 1 else 1
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        compare=None,
+        parallel=True,
+        ncpus=ncpus,
+    )
+    test.run()
diff --git a/autotest/test_par_gwf_rewet.py b/autotest/test_par_gwf_rewet.py
index f8fdc1fdebd..fad3e4b4932 100644
--- a/autotest/test_par_gwf_rewet.py
+++ b/autotest/test_par_gwf_rewet.py
@@ -1,55 +1,46 @@
-import os
-from decimal import Decimal
+"""
+This tests reuses the simulation data in test_gwf_ifmod_rewet.py
+and runs it in parallel on three cpus with
+
+cpu 0: 'refmodel'
+cpu 1: 'leftmodel'
+cpu 2: 'rightmodel'
+
+so we can compare the parallel coupling of 'leftmodel' + 'rightmodel'
+with a serial 'refmodel'
+"""
+
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
-
-# This tests reuses the simulation data in test_gwf_ifmod_rewet.py
-# and runs it in parallel on three cpus with
-#
-# cpu 0: 'refmodel'
-# cpu 1: 'leftmodel'
-# cpu 2: 'rightmodel'
-#
-# so we can compare the parallel coupling of 'leftmodel' + 'rightmodel'
-# with a serial 'refmodel'
-ex = ["par_rewet"]
-
-def build_petsc_db(idx, exdir):
-    from test_gwf_ifmod_rewet import hclose_check, max_inner_it
-    petsc_db_file = os.path.join(exdir, ".petscrc")
-    with open(petsc_db_file, 'w') as petsc_file:
-        petsc_file.write("-ksp_type bicg\n")
-        petsc_file.write("-pc_type bjacobi\n")
-        petsc_file.write("-sub_pc_type ilu\n")
-        petsc_file.write("-sub_pc_factor_levels 2\n")
-        petsc_file.write(f"-dvclose {Decimal(hclose_check):.2E}\n")
-        petsc_file.write(f"-nitermax {max_inner_it}\n")
-        petsc_file.write("-options_left no\n")
-
-def build_model(idx, exdir):
-    from test_gwf_ifmod_rewet import build_model as build_model_ext
-    build_petsc_db(idx, exdir)
-    sim, dummy = build_model_ext(idx, exdir)
+
+cases = ["par_rewet"]
+
+
+def build_models(idx, test):
+    from test_gwf_ifmod_rewet import build_models as build
+
+    sim, dummy = build(idx, test)
     return sim, dummy
 
-def eval_model(test_sim):
-    from test_gwf_ifmod_rewet import compare_to_ref
-    compare_to_ref(test_sim)    
+
+def check_output(idx, test):
+    from test_gwf_ifmod_rewet import check_output as check
+
+    check(idx, test)
+
 
 @pytest.mark.parallel
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, 
-            idxsim=0, make_comparison=False,
-            parallel=True, ncpus=3,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+        parallel=True,
+        ncpus=3,
     )
+    test.run()
diff --git a/autotest/test_par_gwf_xt3d02.py b/autotest/test_par_gwf_xt3d02.py
index d7fc1139a69..a2e954f337a 100644
--- a/autotest/test_par_gwf_xt3d02.py
+++ b/autotest/test_par_gwf_xt3d02.py
@@ -1,55 +1,46 @@
-import os
-from decimal import Decimal
+"""
+This tests reuses the simulation data in test_gwf_ifmod_xt3d02.py
+and runs it in parallel on three cpus with
+
+cpu 0: 'refmodel'
+cpu 1: 'leftmodel'
+cpu 2: 'rightmodel'
+
+so we can compare the parallel coupling of 'leftmodel' + 'rightmodel'
+with a serial 'refmodel' in case of XT3D
+"""
+
 import pytest
+
 from framework import TestFramework
-from simulation import TestSimulation
-
-# This tests reuses the simulation data in test_gwf_ifmod_xt3d02.py
-# and runs it in parallel on three cpus with
-#
-# cpu 0: 'refmodel'
-# cpu 1: 'leftmodel'
-# cpu 2: 'rightmodel'
-#
-# so we can compare the parallel coupling of 'leftmodel' + 'rightmodel'
-# with a serial 'refmodel' in case of XT3D
-ex = ["par_xt3d02"]
-
-def build_petsc_db(idx, exdir):
-    from test_gwf_ifmod_xt3d02 import hclose_check, max_inner_it
-    petsc_db_file = os.path.join(exdir, ".petscrc")
-    with open(petsc_db_file, 'w') as petsc_file:
-        petsc_file.write("-ksp_type bicg\n")
-        petsc_file.write("-pc_type bjacobi\n")
-        petsc_file.write("-sub_pc_type ilu\n")
-        petsc_file.write("-sub_pc_factor_levels 2\n")
-        petsc_file.write(f"-dvclose {Decimal(hclose_check):.2E}\n")
-        petsc_file.write(f"-nitermax {max_inner_it}\n")
-        petsc_file.write("-options_left no\n")
-
-def build_model(idx, exdir):
-    from test_gwf_ifmod_xt3d02 import build_model as build_model_ext
-    build_petsc_db(idx, exdir)
-    sim, dummy = build_model_ext(idx, exdir)
+
+cases = ["par_xt3d02"]
+
+
+def build_models(idx, test):
+    from test_gwf_ifmod_xt3d02 import build_models as build
+
+    sim, dummy = build(idx, test)
     return sim, dummy
 
-def eval_model(test_sim):
-    from test_gwf_ifmod_xt3d02 import compare_to_ref
-    compare_to_ref(test_sim)    
+
+def check_output(idx, test):
+    from test_gwf_ifmod_xt3d02 import check_output as check
+
+    check(idx, test)
+
 
 @pytest.mark.parallel
-@pytest.mark.parametrize(
-    "idx, name",
-    list(enumerate(ex)),
-)
+@pytest.mark.parametrize("idx, name", enumerate(cases))
 def test_mf6model(idx, name, function_tmpdir, targets):
-    test = TestFramework()
-    test.build(build_model, idx, str(function_tmpdir))
-    test.run(
-        TestSimulation(
-            name=name, exe_dict=targets, exfunc=eval_model, 
-            idxsim=0, make_comparison=False,
-            parallel=True, ncpus=3,
-        ),
-        str(function_tmpdir),
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+        parallel=True,
+        ncpus=3,
     )
+    test.run()
diff --git a/autotest/test_par_gwf_xt3d03.py b/autotest/test_par_gwf_xt3d03.py
new file mode 100644
index 00000000000..1ae92085824
--- /dev/null
+++ b/autotest/test_par_gwf_xt3d03.py
@@ -0,0 +1,52 @@
+"""
+This tests reuses the simulation data in test_gwf_ifmod_xt3d03.py
+and runs it in parallel on 5 cpus with
+
+cpu 0: 'ref'
+cpu 1: 'tl'
+cpu 2: 'bl'
+cpu 3: 'tr'
+cpu 4: 'br'
+
+so we can compare the parallel coupling of the 4 models
+with a serial reference case with XT3D enabled everywhere. 
+Particular aspect of this test is the capability to correctly 
+deal with the "Four Corners" issue, where for some connections
+the flux has to be calculated using data from 4 subdomains.
+
+"""
+
+import pytest
+
+from framework import TestFramework
+
+cases = ["par_xt3d03"]
+
+
+def build_models(idx, test):
+    from test_gwf_ifmod_xt3d03 import build_models as build
+
+    sim, dummy = build(idx, test)
+    return sim, dummy
+
+
+def check_output(idx, test):
+    from test_gwf_ifmod_xt3d03 import check_output as check
+
+    check(idx, test)
+
+
+@pytest.mark.parallel
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+        parallel=True,
+        ncpus=5,
+    )
+    test.run()
diff --git a/autotest/test_par_gwt_adv01.py b/autotest/test_par_gwt_adv01.py
new file mode 100644
index 00000000000..2e9647faa56
--- /dev/null
+++ b/autotest/test_par_gwt_adv01.py
@@ -0,0 +1,39 @@
+"""
+This test reuses the simulation data and config in
+test_gwt_adv01_gwtgwt.py and runs it in parallel mode.
+"""
+
+import pytest
+
+from framework import TestFramework
+
+cases = ["par_adv01a_gwtgwt", "par_adv01b_gwtgwt", "par_adv01c_gwtgwt"]
+
+
+def build_models(idx, test):
+    from test_gwt_adv01_gwtgwt import build_models as build
+
+    sim, dummy = build(idx, test)
+    return sim, dummy
+
+
+def check_output(idx, test):
+    from test_gwt_adv01_gwtgwt import check_output as check
+
+    check(idx, test)
+
+
+@pytest.mark.parallel
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+        parallel=True,
+        ncpus=2,
+    )
+    test.run()
diff --git a/autotest/test_par_gwt_dsp01.py b/autotest/test_par_gwt_dsp01.py
new file mode 100644
index 00000000000..dbdee7a26f9
--- /dev/null
+++ b/autotest/test_par_gwt_dsp01.py
@@ -0,0 +1,39 @@
+"""
+This test reuses the simulation data and config in
+test_gwt_dsp01_gwtgwt.py and runs it in parallel mode.
+"""
+
+import pytest
+
+from framework import TestFramework
+
+cases = ["par_dsp01_gwtgwt"]
+
+
+def build_models(idx, test):
+    from test_gwt_dsp01_gwtgwt import build_models as build
+
+    sim, dummy = build(idx, test)
+    return sim, dummy
+
+
+def check_output(idx, test):
+    from test_gwt_dsp01_gwtgwt import check_output as check
+
+    check(idx, test)
+
+
+@pytest.mark.parallel
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+        parallel=True,
+        ncpus=2,
+    )
+    test.run()
diff --git a/autotest/test_par_gwt_henry.py b/autotest/test_par_gwt_henry.py
new file mode 100644
index 00000000000..ee333c6a9cc
--- /dev/null
+++ b/autotest/test_par_gwt_henry.py
@@ -0,0 +1,39 @@
+"""
+This test reuses the simulation data and config in
+test_gwt_henry_gwtgwt.py and runs it in parallel mode.
+"""
+
+import pytest
+
+from framework import TestFramework
+
+cases = ["par-henry-ups", "par-henry-cen", "par-henry-tvd"]
+
+
+def build_models(idx, test):
+    from test_gwt_henry_gwtgwt import build_models as build
+
+    sim, dummy = build(idx, test)
+    return sim, dummy
+
+
+def check_output(idx, test):
+    from test_gwt_henry_gwtgwt import check_output as check
+
+    check(idx, test)
+
+
+@pytest.mark.parallel
+@pytest.mark.parametrize("idx, name", enumerate(cases))
+def test_mf6model(idx, name, function_tmpdir, targets):
+    test = TestFramework(
+        name=name,
+        workspace=function_tmpdir,
+        targets=targets,
+        build=lambda t: build_models(idx, t),
+        check=lambda t: check_output(idx, t),
+        compare=None,
+        parallel=True,
+        ncpus=2,
+    )
+    test.run()
diff --git a/autotest/test_testmodels_mf5to6.py b/autotest/test_testmodels_mf5to6.py
new file mode 100644
index 00000000000..c9948681c75
--- /dev/null
+++ b/autotest/test_testmodels_mf5to6.py
@@ -0,0 +1,85 @@
+import os
+from pathlib import Path
+
+import flopy
+import pytest
+
+from common_regression import get_namefiles, setup_model
+from framework import TestFramework
+
+excluded_models = ["alt_model", "mf2005"]
+
+
+def setup_mf5to6(src, dst) -> Path:
+    Path(dst).mkdir(exist_ok=True)
+    lgrpth = None
+
+    # determine if compare directory exists in directory or if mflgr control
+    # file is in directory
+    listdir = os.listdir(src)
+    for value in listdir:
+        fpth = os.path.join(src, value)
+        if os.path.isfile(fpth):
+            ext = os.path.splitext(fpth)[1]
+            if ".lgr" in ext.lower():
+                lgrpth = fpth
+
+    print(f"Copying files to target workspace: {dst}")
+    # copy lgr files to working directory
+    if lgrpth is not None:
+        npth = lgrpth
+        setup_model(lgrpth, dst)
+    # copy MODFLOW-2005, MODFLOW-NWT, or MODFLOW-USG files to working directory
+    else:
+        npths = get_namefiles(src)
+        if len(npths) < 1:
+            msg = f"No name files in source workspace: {src}"
+            print(msg)
+            assert False
+        npth = npths[0]
+        setup_model(npth, dst)
+
+    return Path(npth)
+
+
+@pytest.mark.repo
+@pytest.mark.regression
+def test_model(
+    function_tmpdir,
+    original_regression,
+    targets,
+    # https://modflow-devtools.readthedocs.io/en/latest/md/fixtures.html#modflow-2005-test-models
+    test_model_mf5to6,
+):
+    model_path = test_model_mf5to6.parent
+    model_name = model_path.name
+    if model_name in excluded_models:
+        pytest.skip(f"Skipping: {model_name} (excluded)")
+
+    test = TestFramework(
+        name=model_path.name,
+        workspace=model_path,
+        targets=targets,
+        compare="auto" if original_regression else "mf6_regression",
+        verbose=False,
+    )
+
+    # run the mf5to6 converter
+    mf5to6_workspace = function_tmpdir / "mf5to6"
+    npth = setup_mf5to6(model_path, mf5to6_workspace)
+    nam = os.path.basename(npth)
+    exe = os.path.abspath(targets["mf5to6"])
+    print("MODFLOW 5 to 6 converter run for", nam, "using executable", exe)
+    success, _ = flopy.run_model(
+        exe,
+        nam,
+        model_ws=mf5to6_workspace,
+        normal_msg="Program terminated normally",
+        cargs="mf6",
+    )
+    assert success
+
+    # run mf6
+    mf6_workspace = function_tmpdir / "mf6"
+    test.setup(mf5to6_workspace, mf6_workspace)
+    test.run()
diff --git a/autotest/test_testmodels_mf6.py b/autotest/test_testmodels_mf6.py
new file mode 100644
index 00000000000..22382d55b9c
--- /dev/null
+++ b/autotest/test_testmodels_mf6.py
@@ -0,0 +1,42 @@
+import pytest
+
+from framework import TestFramework
+
+excluded_models = [
+    "alt_model",
+    "test205_gwtbuy-henrytidal",
+    # todo reinstate when flopy fixed: https://github.com/modflowpy/flopy/issues/2053
+    "test001a_Tharmonic_tabs",
+    "test004_bcfss",
+    "test014_NWTP3Low_dev",
+    "test041_flowdivert_nwt_dev",
+]
+
+
+@pytest.mark.repo
+@pytest.mark.regression
+def test_model(
+    function_tmpdir,
+    markers,
+    original_regression,
+    targets,
+    # https://modflow-devtools.readthedocs.io/en/latest/md/fixtures.html#modflow-6-test-models
+    test_model_mf6,
+):
+    model_path = test_model_mf6.parent
+    model_name = model_path.name
+    excluded = model_name in excluded_models
+    dev_only = "dev" in model_name and "not developmode" in markers
+    if excluded or dev_only:
+        reason = "excluded" if excluded else "developmode only"
+        pytest.skip(f"Skipping: {model_name} ({reason})")
+
+    test = TestFramework(
+        name=model_name,
+        workspace=model_path,
+        targets=targets,
+        compare="auto" if original_regression else "mf6_regression",
+        verbose=False,
+    )
+    test.setup(model_path, function_tmpdir)
+    test.run()
diff --git a/autotest/test_z01_testmodels_mf6.py b/autotest/test_z01_testmodels_mf6.py
deleted file mode 100644
index 48187b4197d..00000000000
--- a/autotest/test_z01_testmodels_mf6.py
+++ /dev/null
@@ -1,67 +0,0 @@
-import pytest
-from conftest import should_compare
-from simulation import TestSimulation
-
-excluded_models = ["alt_model", "test205_gwtbuy-henrytidal"]
-excluded_comparisons = {
-    "test001e_noUZF_3lay": ["6.2.1",],
-    "test005_advgw_tidal": ["6.2.1",],
-    "test017_Crinkle": ["6.2.1",],
-    "test028_sfr": ["6.2.1",],
-    "test028_sfr_rewet": ["6.2.1",],
-    "test028_sfr_rewet_nr": ["6.2.1",],
-    "test028_sfr_rewet_simple": ["6.2.1",],
-    "test028_sfr_simple": ["6.2.1",],
-    "test034_nwtp2": ["6.2.1",],
-    "test034_nwtp2_1d": ["6.2.1",],
-    "test045_lake1tr_nr": ["6.2.1",],
-    "test045_lake2tr": ["6.2.1",],
-    "test045_lake2tr_nr": ["6.2.1",],
-    "test051_uzfp2": ["6.2.1",],
-    "test051_uzfp3_lakmvr_v2": ["6.2.1",],
-    "test051_uzfp3_wellakmvr_v2": ["6.2.1",],
-    "test045_lake4ss": ["6.2.2",],
-    "test056_mt3dms_usgs_gwtex_dev": ["6.4.1",],
-    "test056_mt3dms_usgs_gwtex_IR_dev": ["6.4.1",],
-    "test059_mvlake_lak_ss": ["6.4.1",],
-    "test045_lake2tr_xsfrc_dev": ["6.4.1",],
-    "test045_lake2tr_xsfrd_dev": ["6.4.1",],
-    "test045_lake2tr_xsfre_dev": ["6.4.1",],
-    "test045_lake4ss": ["6.4.1",],
-    "test045_lake4ss_dev": ["6.4.1",],
-    "test045_lake4ss_il_dev": ["6.4.1",],
-    "test045_lake4ss_nr_dev": ["6.4.1",],
-    "test045_lake4ss_nr_embedded": ["6.4.1",],
-}
-
-
-@pytest.mark.repo
-@pytest.mark.regression
-def test_model(function_tmpdir, test_model_mf6, targets, original_regression, markers):
-    exdir = test_model_mf6.parent
-    name = exdir.name
-
-    if name in excluded_models:
-        pytest.skip(f"Excluding mf6 model '{name}'")
-    
-    if "dev" in name and "not developmode" in markers:
-        pytest.skip(f"Skipping mf6 model '{name}' (develop mode only)")
-
-    sim = TestSimulation(
-        name=name,
-        exe_dict=targets,
-        mf6_regression=not original_regression,
-        cmp_verbose=False,
-        make_comparison=should_compare(name, excluded_comparisons, targets),
-        simpath=str(exdir),
-    )
-
-    src = exdir
-    dst = str(function_tmpdir)
-
-    # Run the MODFLOW 6 simulation and compare to results generated using
-    # 1) the current MODFLOW 6 release, 2) an existing head file, or 3) or
-    # appropriate MODFLOW-2005, MODFLOW-NWT, MODFLOW-USG, or MODFLOW-LGR run.
-    sim.setup(src, dst)
-    sim.run()
-    sim.compare()
diff --git a/autotest/test_z02_testmodels_mf5to6.py b/autotest/test_z02_testmodels_mf5to6.py
deleted file mode 100644
index ef030661ad3..00000000000
--- a/autotest/test_z02_testmodels_mf5to6.py
+++ /dev/null
@@ -1,105 +0,0 @@
-import os
-
-import flopy
-import pytest
-from common_regression import get_namefiles, model_setup
-from conftest import should_compare
-from simulation import TestSimulation
-
-sfmt = "{:25s} - {}"
-excluded_models = ["alt_model", "mf2005"]
-excluded_comparisons = {
-    "testPr2": ["6.2.1",],
-    "testUzfLakSfr": ["6.2.1",],
-    "testUzfLakSfr_laketable": ["6.2.1",],
-    "testWetDry": ["6.2.1",],
-}
-
-
-@pytest.mark.repo
-@pytest.mark.regression
-def test_model(
-    function_tmpdir, test_model_mf5to6, targets, original_regression
-):
-    exdir = test_model_mf5to6.parent
-    name = exdir.name
-
-    if name in excluded_models:
-        pytest.skip(f"Excluding mf5to6 model: {name}")
-
-    sim = TestSimulation(
-        name=exdir.name,
-        exe_dict=targets,
-        mf6_regression=not original_regression,
-        cmp_verbose=False,
-        make_comparison=should_compare(name, excluded_comparisons, targets),
-        simpath=str(exdir),
-    )
-
-    src = sim.simpath
-    dst = str(function_tmpdir)
-
-    # set lgrpth to None
-    lgrpth = None
-
-    # determine if compare directory exists in directory or if mflgr control
-    # file is in directory
-    listdir = os.listdir(src)
-    for value in listdir:
-        fpth = os.path.join(src, value)
-        if os.path.isfile(fpth):
-            ext = os.path.splitext(fpth)[1]
-            if ".lgr" in ext.lower():
-                lgrpth = fpth
-
-    print("Copying files to working directory")
-    # copy lgr files to working directory
-    if lgrpth is not None:
-        npth = lgrpth
-        model_setup(lgrpth, dst)
-    # copy MODFLOW-2005, MODFLOW-NWT, or MODFLOW-USG files to working directory
-    else:
-        npths = get_namefiles(src)
-        if len(npths) < 1:
-            msg = f"No name files in {src}"
-            print(msg)
-            assert False
-        npth = npths[0]
-        model_setup(npth, dst)
-
-    # run the mf5to6 converter
-    exe = os.path.abspath(targets["mf5to6"])
-    print(sfmt.format("using executable", exe))
-    nmsg = "Program terminated normally"
-    try:
-        nam = os.path.basename(npth)
-        success, buff = flopy.run_model(
-            exe,
-            nam,
-            model_ws=dst,
-            silent=False,
-            report=True,
-            normal_msg=nmsg,
-            cargs="mf6",
-        )
-        msg = sfmt.format("MODFLOW 5 to 6 run", nam)
-        if success:
-            print(msg)
-        else:
-            print("ERROR: " + msg)
-    except:
-        msg = sfmt.format("MODFLOW 5 to 6 run", nam)
-        print("ERROR: " + msg)
-        success = False
-
-    assert success, msg
-
-    # model setup
-    src = dst
-    dst = function_tmpdir / "models"
-    sim.setup(src, dst)
-
-    # Run the MODFLOW 6 simulation and compare to existing head file or
-    # appropriate MODFLOW-2005, MODFLOW-NWT, MODFLOW-USG, or MODFLOW-LGR run.
-    sim.run()
-    sim.compare()
diff --git a/autotest/test_z03_examples.py b/autotest/test_z03_examples.py
deleted file mode 100644
index 124d8f9229a..00000000000
--- a/autotest/test_z03_examples.py
+++ /dev/null
@@ -1,81 +0,0 @@
-import pytest
-from conftest import should_compare
-from simulation import TestSimulation
-
-# skip nested models
-# ex-gwf-csub-p02c has subdirs like 'es-001', 'hb-100'
-# all others just have 2 folders 'mf6gwf' and 'mf6gwt'
-excluded_models = [
-    "ex-gwf-csub-p02c",
-    "ex-gwt-hecht-mendez-b",
-    "ex-gwt-hecht-mendez-c",
-    "ex-gwt-keating",
-    "ex-gwt-moc3d-p01a",
-    "ex-gwt-moc3d-p01b",
-    "ex-gwt-moc3d-p01c",
-    "ex-gwt-moc3d-p01d",
-    "ex-gwt-moc3d-p02",
-    "ex-gwt-moc3d-p02tg",
-    "ex-gwt-mt3dms-p02a",
-    "ex-gwt-mt3dms-p02b",
-    "ex-gwt-mt3dms-p02c",
-    "ex-gwt-mt3dms-p02d",
-    "ex-gwt-mt3dms-p02e",
-    "ex-gwt-mt3dms-p02f",
-    "ex-gwt-mt3dsupp631",
-    "ex-gwt-mt3dsupp632a",
-    "ex-gwt-mt3dsupp632b",
-    "ex-gwt-mt3dsupp632c",
-    "ex-gwt-mt3dsupp82",
-    "ex-gwt-prudic2004t2",
-]
-excluded_comparisons = {
-    "ex-gwf-capture": ["6.2.1"],
-    "ex-gwf-sagehen": ["6.2.1"],
-    "ex-gwf-sfr-p01b": ["6.2.1"],
-    "ex-gwf-nwt-p02a": ["6.2.1"],
-    "ex-gwf-lak-p01": ["6.2.1"],
-    "ex-gwf-lak-p02": ["6.2.1"],
-    "ex-gwf-nwt-p02b": ["6.2.1"],
-    "ex-gwf-advtidal": ["6.2.1"],
-    "ex-gwf-sfr-p01": ["6.2.1"],
-    "ex-gwf-lgr": ["6.2.2"],
-    "ex-gwt-rotate": ["6.2.2"],
-    "ex-gwt-gwtgwt-mt3dms-p10": ["6.3.0"],
-    "ex-gwf-lak-p01": ["6.4.1"],
-}
-
-
-@pytest.mark.large
-@pytest.mark.repo
-@pytest.mark.regression
-@pytest.mark.slow
-def test_scenario(function_tmpdir, example_scenario, targets):
-    name, namefiles = example_scenario
-    exdirs = [nf.parent for nf in namefiles]
-
-    if name in excluded_models:
-        pytest.skip(f"Excluding mf6 model: {name}")
-
-    for exdir in exdirs:
-        model_name = f"{name}_{exdir.name}"
-        workspace = function_tmpdir / model_name
-        sim = TestSimulation(
-            name=model_name,
-            exe_dict=targets.as_dict(),
-            mf6_regression=True,
-            cmp_verbose=False,
-            make_comparison=should_compare(
-                name, excluded_comparisons, targets
-            ),
-            simpath=str(exdir),
-        )
-
-        src = sim.simpath
-        dst = str(workspace)
-
-        # Run the MODFLOW 6 simulation and compare to existing head file or
-        # appropriate MODFLOW-2005, MODFLOW-NWT, MODFLOW-USG, or MODFLOW-LGR run.
-        sim.setup(src, dst)
-        sim.run()
-        sim.compare()
diff --git a/autotest/test_z03_largetestmodels.py b/autotest/test_z03_largetestmodels.py
deleted file mode 100644
index c5f9175579a..00000000000
--- a/autotest/test_z03_largetestmodels.py
+++ /dev/null
@@ -1,46 +0,0 @@
-import pytest
-from conftest import should_compare
-from simulation import TestSimulation
-
-excluded_models = []
-excluded_comparisons = {
-    "test1004_mvlake_laksfr_tr": ["6.4.1",],
-    "test1004_mvlake_lak_tr": ["6.4.1",],
-    "test1003_MNW2_Fig28": ["6.2.1",],
-    "test1001_Peterson": ["6.2.1",],
-}
-
-
-@pytest.mark.large
-@pytest.mark.repo
-@pytest.mark.regression
-@pytest.mark.slow
-def test_model(
-    function_tmpdir, large_test_model, targets, original_regression, markers
-):
-    exdir = large_test_model.parent
-    name = exdir.name
-
-    if name in excluded_models:
-        pytest.skip(f"Excluding large mf6 model '{name}'")
-    
-    if "dev" in name and "not developmode" in markers:
-        pytest.skip(f"Skipping large mf6 model '{name}' (develop mode only)")
-
-    sim = TestSimulation(
-        name=name,
-        exe_dict=targets.as_dict(),
-        mf6_regression=not original_regression,
-        cmp_verbose=False,
-        make_comparison=should_compare(name, excluded_comparisons, targets),
-        simpath=str(exdir),
-    )
-
-    src = sim.simpath
-    dst = str(function_tmpdir)
-
-    # Run the MODFLOW 6 simulation and compare to existing head file or
-    # appropriate MODFLOW-2005, MODFLOW-NWT, MODFLOW-USG, or MODFLOW-LGR run.
-    sim.setup(src, dst)
-    sim.run()
-    sim.compare()
diff --git a/autotest/tester.f90 b/autotest/tester.f90
new file mode 100644
index 00000000000..ed297ef643c
--- /dev/null
+++ b/autotest/tester.f90
@@ -0,0 +1,68 @@
+program tester
+  use, intrinsic :: iso_fortran_env, only: error_unit
+  use testdrive, only: run_testsuite, new_testsuite, testsuite_type, &
+    & select_suite, run_selected, get_argument
+  use TestArrayHandlers, only: collect_arrayhandlers
+  use TestDevFeature, only: collect_dev_feature
+  use TestGeomUtil, only: collect_geomutil
+  use TestHashTable, only: collect_hashtable
+  use TestInputOutput, only: collect_inputoutput
+  use TestList, only: collect_list
+  use TestMathUtil, only: collect_mathutil
+  use TestMessage, only: collect_message
+  use TestSim, only: collect_sim
+  implicit none
+  integer :: stat, is
+  character(len=:), allocatable :: suite_name, test_name
+  type(testsuite_type), allocatable :: testsuites(:)
+  character(len=*), parameter :: fmt = '("#", *(1x, a))'
+
+  stat = 0
+  testsuites = [ &
+               new_testsuite("ArrayHandlers", collect_arrayhandlers), &
+               new_testsuite("DevFeature", collect_dev_feature), &
+               new_testsuite("GeomUtil", collect_geomutil), &
+               new_testsuite("HashTable", collect_hashtable), &
+               new_testsuite("InputOutput", collect_inputoutput), &
+               new_testsuite("List", collect_list), &
+               new_testsuite("MathUtil", collect_mathutil), &
+               new_testsuite("Message", collect_message), &
+               new_testsuite("Sim", collect_sim) &
+               ]
+
+  call get_argument(1, suite_name)
+  call get_argument(2, test_name)
+
+  if (allocated(suite_name)) then
+    is = select_suite(testsuites, suite_name)
+    if (is > 0 .and. is <= size(testsuites)) then
+      if (allocated(test_name)) then
+        write (error_unit, fmt) "Suite:", testsuites(is)%name
+        call run_selected(testsuites(is)%collect, test_name, error_unit, stat)
+        if (stat < 0) then
+          error stop 1
+        end if
+      else
+        write (error_unit, fmt) "Testing:", testsuites(is)%name
+        call run_testsuite(testsuites(is)%collect, error_unit, stat)
+      end if
+    else
+      write (error_unit, fmt) "Available testsuites"
+      do is = 1, size(testsuites)
+        write (error_unit, fmt) "-", testsuites(is)%name
+      end do
+      error stop 1
+    end if
+  else
+    do is = 1, size(testsuites)
+      write (error_unit, fmt) "Testing:", testsuites(is)%name
+      call run_testsuite(testsuites(is)%collect, error_unit, stat)
+    end do
+  end if
+
+  if (stat > 0) then
+    write (error_unit, '(i0, 1x, a)') stat, "test(s) failed!"
+    error stop 1
+  end if
+
+end program tester
diff --git a/autotest/update_flopy.py b/autotest/update_flopy.py
index d7c2aedd3a2..bf62eabc21c 100644
--- a/autotest/update_flopy.py
+++ b/autotest/update_flopy.py
@@ -8,6 +8,7 @@
 
 import flopy
 import pytest
+
 from conftest import project_root_path
 
 dfn_path = project_root_path / "doc" / "mf6io" / "mf6ivar" / "dfn"
diff --git a/code.json b/code.json
index 99dbdf41b3c..0538ab48eb0 100644
--- a/code.json
+++ b/code.json
@@ -18,9 +18,9 @@
             "email": "langevin@usgs.gov"
         },
         "laborHours": -1,
-        "version": "6.4.2",
+        "version": "6.4.3",
         "date": {
-            "metadataLastUpdated": "2023-06-28"
+            "metadataLastUpdated": "2024-02-07"
         },
         "organization": "U.S. Geological Survey",
         "permissions": {
diff --git a/distribution/benchmark.py b/distribution/benchmark.py
index f5c319804e7..b92d533fec3 100644
--- a/distribution/benchmark.py
+++ b/distribution/benchmark.py
@@ -27,14 +27,16 @@
 _is_windows = sys.platform.lower() == "win32"
 _app_ext = ".exe" if _is_windows else ""
 _soext = ".dll" if _is_windows else ".so"
+_ostag = "win64" if _is_windows else "linux" if sys.platform.lower().startswith("linux") else "mac"
 
 
 def download_previous_version(output_path: PathLike) -> Tuple[str, Path]:
     output_path = Path(output_path).expanduser().absolute()
     version = get_latest_version(_github_repo)
+    distname = f"mf{version}_{_ostag}"
     url = (
         f"https://github.com/{_github_repo}"
-        + f"/releases/download/{version}/mf{version}.zip"
+        + f"/releases/download/{version}/{distname}.zip"
     )
     download_and_unzip(
         url,
@@ -42,7 +44,7 @@ def download_previous_version(output_path: PathLike) -> Tuple[str, Path]:
         verbose=True,
     )
 
-    return version, output_path / f"mf{version}"
+    return version, output_path / distname
 
 
 def get_mf6_cmdargs(app, argv, text="mf6:", verbose=False):
diff --git a/distribution/build_dist.py b/distribution/build_dist.py
index f60b76302c6..4d8efdfc8f6 100644
--- a/distribution/build_dist.py
+++ b/distribution/build_dist.py
@@ -1,14 +1,12 @@
 import argparse
 import os
 import platform
-import shutil
 import sys
 import textwrap
-from collections import namedtuple
 from os import PathLike, environ
 from pathlib import Path
 from pprint import pprint
-from shutil import copytree
+from shutil import copy, copyfile, copytree, ignore_patterns
 
 import pytest
 from modflow_devtools.build import meson_build
@@ -18,55 +16,18 @@
 
 from build_docs import build_documentation
 from build_makefiles import (
-    build_mf6_makefile,
     build_mf5to6_makefile,
+    build_mf6_makefile,
     build_zbud6_makefile,
 )
 from utils import get_project_root_path, run_command
 
-_project_name = "MODFLOW 6"
-
 # default paths
 _project_root_path = get_project_root_path()
-_version_texf_path = _project_root_path / "doc" / "version.tex"
 _examples_repo_path = _project_root_path.parent / "modflow6-examples"
-_examples_path = _examples_repo_path / "examples"
 _build_path = _project_root_path / "builddir"
-_bin_path = _project_root_path / "bin"
-_docs_path = _project_root_path / "doc"
-_benchmarks_path = _project_root_path / "distribution" / ".benchmarks"
-
-# top-level directories included in distribution
-_included_dir_paths = [
-    "bin",
-    "doc",
-    "examples",
-    "src",
-    "srcbmi",
-    "msvs",
-    "make",
-    "utils",
-]
-
-Makefile = namedtuple("Makefile", ["app", "src_path", "out_path"])
-
-
-# makefiles included in distribution
-_makefiles = [
-    Makefile(app="mf6", src_path=_project_root_path / "src", out_path=Path("make")),
-    Makefile(
-        app="zbud6",
-        src_path=_project_root_path / "utils" / "zonebudget" / "src",
-        out_path=Path("utils") / "zonebudget" / "make",
-    ),
-    Makefile(
-        app="mf5to6",
-        src_path=_project_root_path / "utils" / "mf5to6" / "src",
-        out_path=Path("utils") / "mf5to6" / "make",
-    ),
-]
-
-# system-specific filenames, extensions, etc
+
+# OS-specific extensions
 _system = platform.system()
 _eext = ".exe" if _system == "Windows" else ""
 _soext = ".dll" if _system == "Windows" else ".so" if _system == "Linux" else ".dylib"
@@ -95,30 +56,32 @@ def copy_sources(output_path: PathLike):
         str(source_msvs_path / "mf6bmi.sln"),
         str(source_msvs_path / "mf6bmi.vfproj"),
     ]:
-        shutil.copy(d, output_path / "msvs")
+        copy(d, output_path / "msvs")
 
-    ignored = shutil.ignore_patterns(".DS_Store")
+    ignored = [".DS_Store"]
 
-    # copy top-level meson.build
-    shutil.copy(_project_root_path / "meson.build", output_path)
+    # copy top-level meson.build and meson.options
+    copy(_project_root_path / "meson.build", output_path)
+    copy(_project_root_path / "meson.options", output_path)
 
     # copy source folder
     src_path = _project_root_path / "src"
     dst_path = output_path / "src"
     print(f"Copying {src_path} to {dst_path}")
-    copytree(src_path, dst_path, ignore=ignored)
+    copytree(src_path, dst_path, ignore=ignore_patterns(*ignored))
 
     # copy srcbmi folder
     src_path = _project_root_path / "srcbmi"
     dst_path = output_path / "srcbmi"
     print(f"Copying {src_path} to {dst_path}")
-    copytree(src_path, dst_path, ignore=ignored)
+    copytree(src_path, dst_path, ignore=ignore_patterns(*ignored))
 
     # copy utils folder
     src_path = _project_root_path / "utils"
     dst_path = output_path / "utils"
     print(f"Copying {src_path} to {dst_path}")
-    copytree(src_path, dst_path, ignore=ignored)
+    ignored.extend(["idmloader"])
+    copytree(src_path, dst_path, ignore=ignore_patterns(*ignored))
 
 
 def test_copy_sources(tmp_path):
@@ -134,6 +97,14 @@ def test_copy_sources(tmp_path):
     assert (tmp_path / "utils" / "meson.build").is_file()
     assert (tmp_path / "msvs" / "mf6.sln").is_file()
 
+    assert (tmp_path / "utils").is_dir()
+    assert (tmp_path / "utils" / "mf5to6").is_dir()
+    assert (tmp_path / "utils" / "zonebudget").is_dir()
+    assert (tmp_path / "utils" / "mf5to6" / "pymake").is_dir()
+    assert (tmp_path / "utils" / "zonebudget" / "pymake").is_dir()
+    assert not (tmp_path / "utils" / "idmloader").is_dir()
+    
+
 
 def build_examples(examples_repo_path: PathLike, overwrite: bool = False):
     examples_repo_path = Path(examples_repo_path).expanduser().absolute()
@@ -232,10 +203,6 @@ def setup_examples(
                 print(f"Execute permission set for {script_path}")
 
 
-def test_setup_examples():
-    pass
-
-
 def build_programs_meson(
     build_path: PathLike, bin_path: PathLike, overwrite: bool = False
 ):
@@ -278,10 +245,10 @@ def build_makefiles(output_path: PathLike):
     # create and copy mf6 makefile
     build_mf6_makefile()
     (output_path / "make").mkdir(parents=True, exist_ok=True)
-    shutil.copyfile(
+    copyfile(
         _project_root_path / "make" / "makefile", output_path / "make" / "makefile"
     )
-    shutil.copyfile(
+    copyfile(
         _project_root_path / "make" / "makedefaults",
         output_path / "make" / "makedefaults",
     )
@@ -290,10 +257,10 @@ def build_makefiles(output_path: PathLike):
     build_zbud6_makefile()
     rel_path = Path("utils") / "zonebudget" / "make"
     (output_path / rel_path).mkdir(parents=True, exist_ok=True)
-    shutil.copyfile(
+    copyfile(
         _project_root_path / rel_path / "makefile", output_path / rel_path / "makefile"
     )
-    shutil.copyfile(
+    copyfile(
         _project_root_path / rel_path / "makedefaults",
         output_path / rel_path / "makedefaults",
     )
@@ -302,10 +269,10 @@ def build_makefiles(output_path: PathLike):
     build_mf5to6_makefile()
     rel_path = Path("utils") / "mf5to6" / "make"
     (output_path / rel_path).mkdir(parents=True, exist_ok=True)
-    shutil.copyfile(
+    copyfile(
         _project_root_path / rel_path / "makefile", output_path / rel_path / "makefile"
     )
-    shutil.copyfile(
+    copyfile(
         _project_root_path / rel_path / "makedefaults",
         output_path / rel_path / "makedefaults",
     )
@@ -345,32 +312,32 @@ def build_distribution(
     )
 
     # code.json metadata
-    shutil.copy(_project_root_path / "code.json", output_path)
+    copy(_project_root_path / "code.json", output_path)
 
     # full releases include examples, source code, makefiles and docs
-    if full:
-        # examples
-        setup_examples(
-            bin_path=output_path / "bin",
-            examples_path=output_path / "examples",
-            overwrite=overwrite,
-        )
+    if not full:
+        return
+
+    # examples
+    setup_examples(
+        bin_path=output_path / "bin",
+        examples_path=output_path / "examples",
+        overwrite=overwrite,
+    )
 
-        # copy source code files
-        copy_sources(output_path=output_path)
+    # copy source code files
+    copy_sources(output_path=output_path)
 
-        # build and copy makefiles
-        build_makefiles(output_path=output_path)
+    # build and copy makefiles
+    build_makefiles(output_path=output_path)
 
-        # docs
-        build_documentation(
-            bin_path=output_path / "bin",
-            output_path=output_path / "doc",
-            examples_repo_path=examples_repo_path,
-            # benchmarks_path=_benchmarks_path / "run-time-comparison.md",
-            full=full,
-            overwrite=overwrite,
-        )
+    # docs
+    build_documentation(
+        bin_path=output_path / "bin",
+        full=full,
+        output_path=output_path / "doc",
+        overwrite=overwrite,
+    )
 
 
 @requires_exe("pdflatex")
@@ -446,13 +413,6 @@ def test_build_distribution(tmp_path, full):
         default=str(_examples_repo_path),
         help="Path to directory containing modflow6 example models",
     )
-    # parser.add_argument(
-    #     "-b",
-    #     "--benchmarks-path",
-    #     required=False,
-    #     default=str(_project_root_path / "distribution" / ".benchmarks"),
-    #     help="Path to directory containing benchmark results"
-    # )
     parser.add_argument(
         "--full",
         required=False,
@@ -469,7 +429,6 @@ def test_build_distribution(tmp_path, full):
         help="Recreate and overwrite existing artifacts",
     )
     args = parser.parse_args()
-
     build_path = Path(args.build_path)
     out_path = Path(args.output_path)
     examples_repo_path = (
diff --git a/distribution/build_docs.py b/distribution/build_docs.py
index efc4c8bbc0c..3c74f642f13 100644
--- a/distribution/build_docs.py
+++ b/distribution/build_docs.py
@@ -5,7 +5,7 @@
 import sys
 import textwrap
 from datetime import datetime
-from os import PathLike
+from os import PathLike, environ
 from pathlib import Path
 from pprint import pprint
 from tempfile import TemporaryDirectory
@@ -17,24 +17,24 @@
 from flaky import flaky
 from modflow_devtools.build import meson_build
 from modflow_devtools.download import (
-    list_artifacts,
+    download_and_unzip,
     download_artifact,
     get_release,
-    download_and_unzip,
+    list_artifacts,
 )
 from modflow_devtools.markers import requires_exe, requires_github
-from modflow_devtools.misc import set_dir, run_cmd, is_in_ci
+from modflow_devtools.misc import is_in_ci, run_cmd, set_dir
 
 from benchmark import run_benchmarks
-from utils import convert_line_endings
-from utils import get_project_root_path
+from utils import convert_line_endings, get_project_root_path
 
+# paths
 _project_root_path = get_project_root_path()
 _bin_path = _project_root_path / "bin"
 _examples_repo_path = _project_root_path.parent / "modflow6-examples"
 _release_notes_path = _project_root_path / "doc" / "ReleaseNotes"
 _distribution_path = _project_root_path / "distribution"
-_benchmarks_path = _project_root_path / "distribution" / ".benchmarks"
+_benchmarks_dir_path = _project_root_path / "distribution" / ".benchmarks"
 _docs_path = _project_root_path / "doc"
 _dev_dist_tex_paths = [
     _docs_path / "mf6io" / "mf6io.tex",
@@ -47,12 +47,13 @@
     _docs_path / "ConverterGuide" / "converter_mf5to6.tex",
     _docs_path / "SuppTechInfo" / "mf6suptechinfo.tex",
 ]
+
+# OS-specific extensions
 _system = platform.system()
 _eext = ".exe" if _system == "Windows" else ""
 _soext = ".dll" if _system == "Windows" else ".so" if _system == "Linux" else ".dylib"
 
-
-# publications included in distribution docs
+# publications included in full dist docs
 _publication_urls = [
     "https://pubs.usgs.gov/tm/06/a55/tm6a55.pdf",
     "https://pubs.usgs.gov/tm/06/a56/tm6a56.pdf",
@@ -103,16 +104,21 @@ def clean_tex_files():
     assert not os.path.isfile(str(pth) + ".pdf")
 
 
-def download_benchmarks(output_path: PathLike, verbose: bool = False) -> Optional[Path]:
+def download_benchmarks(
+    output_path: PathLike, verbose: bool = False, repo_owner: str = "MODFLOW-USGS"
+) -> Optional[Path]:
     output_path = Path(output_path).expanduser().absolute()
     name = "run-time-comparison"  # todo make configurable
-    repo = "MODFLOW-USGS/modflow6"  # todo make configurable, add pytest/cli args
+    repo = f"{repo_owner}/modflow6"  # todo make configurable, add pytest/cli args
     artifacts = list_artifacts(repo, name=name, verbose=verbose)
     artifacts = sorted(
         artifacts,
         key=lambda a: datetime.strptime(a["created_at"], "%Y-%m-%dT%H:%M:%SZ"),
         reverse=True,
     )
+    artifacts = [
+        a for a in artifacts if a["workflow_run"]["head_branch"] == "develop"  # todo make configurable
+    ]
     most_recent = next(iter(artifacts), None)
     print(f"Found most recent benchmarks (artifact {most_recent['id']})")
     if most_recent:
@@ -127,21 +133,32 @@ def download_benchmarks(output_path: PathLike, verbose: bool = False) -> Optiona
         return None
 
 
+@pytest.fixture
+def github_user() -> Optional[str]:
+    return environ.get("GITHUB_USER", None)
+
+
 @flaky
 @requires_github
-def test_download_benchmarks(tmp_path):
-    path = download_benchmarks(tmp_path, verbose=True)
+def test_download_benchmarks(tmp_path, github_user):
+    path = download_benchmarks(
+        tmp_path,
+        verbose=True,
+        repo_owner=github_user if github_user else "MODFLOW-USGS",
+    )
     if path:
         assert path.name == "run-time-comparison.md"
 
 
-def build_benchmark_tex(output_path: PathLike, overwrite: bool = False):
-    _benchmarks_path.mkdir(parents=True, exist_ok=True)
-    benchmarks_path = _benchmarks_path / "run-time-comparison.md"
+def build_benchmark_tex(
+    output_path: PathLike, overwrite: bool = False, repo_owner: str = "MODFLOW-USGS"
+):
+    _benchmarks_dir_path.mkdir(parents=True, exist_ok=True)
+    benchmarks_path = _benchmarks_dir_path / "run-time-comparison.md"
 
     # download benchmark artifacts if any exist on GitHub
     if not benchmarks_path.is_file():
-        benchmarks_path = download_benchmarks(_benchmarks_path)
+        benchmarks_path = download_benchmarks(_benchmarks_dir_path, repo_owner=repo_owner)
 
     # run benchmarks again if no benchmarks found on GitHub or overwrite requested
     if overwrite or not benchmarks_path.is_file():
@@ -162,7 +179,7 @@ def build_benchmark_tex(output_path: PathLike, overwrite: bool = False):
         )
         assert not ret, out + err
         assert tex_path.is_file()
-
+    
     if (_distribution_path / f"{benchmarks_path.stem}.md").is_file():
         assert (_docs_path / "ReleaseNotes" / f"{benchmarks_path.stem}.tex").is_file()
 
@@ -170,7 +187,7 @@ def build_benchmark_tex(output_path: PathLike, overwrite: bool = False):
 @flaky
 @requires_github
 def test_build_benchmark_tex(tmp_path):
-    benchmarks_path = _benchmarks_path / "run-time-comparison.md"
+    benchmarks_path = _benchmarks_dir_path / "run-time-comparison.md"
     tex_path = _distribution_path / f"{benchmarks_path.stem}.tex"
 
     try:
@@ -180,6 +197,22 @@ def test_build_benchmark_tex(tmp_path):
         tex_path.unlink(missing_ok=True)
 
 
+def build_deprecations_tex():
+    deprecations_path = _docs_path / "mf6io" / "mf6ivar" / "md" / "deprecations.md"
+
+    # convert markdown deprecations to LaTeX
+    with set_dir(_release_notes_path):
+        tex_path = Path("deprecations.tex")
+        tex_path.unlink(missing_ok=True)
+        out, err, ret = run_cmd(
+            sys.executable, "mk_deprecations.py", deprecations_path, verbose=True
+        )
+        assert not ret, out + err
+        assert tex_path.is_file()
+    
+    assert (_docs_path / "ReleaseNotes" / f"{deprecations_path.stem}.tex").is_file()
+
+
 def build_mf6io_tex_from_dfn(overwrite: bool = False):
     if overwrite:
         clean_tex_files()
@@ -426,19 +459,15 @@ def test_build_pdfs_from_tex(tmp_path):
 
 def build_documentation(
     bin_path: PathLike,
-    output_path: PathLike,
-    examples_repo_path: PathLike,
-    # Example to use to render sample mf6 output in the docs.
-    # Must be a valid directory in modflow6-examples/examples
-    example_for_sample: str = "ex-gwf-twri01",
     full: bool = False,
+    output_path: Optional[PathLike] = None,
     overwrite: bool = False,
+    repo_owner: str = "MODFLOW-USGS",
 ):
-    print(f"Building {'full' if full else 'full'} documentation")
+    print(f"Building {'full' if full else 'minimal'} documentation")
 
     bin_path = Path(bin_path).expanduser().absolute()
     output_path = Path(output_path).expanduser().absolute()
-    examples_repo_path = Path(examples_repo_path).expanduser().absolute()
 
     # make sure output directory exists
     output_path.mkdir(parents=True, exist_ok=True)
@@ -448,25 +477,27 @@ def build_documentation(
 
     # build LaTeX input/output example model docs
     with TemporaryDirectory() as temp:
-        temp_path = Path(temp)
+        example_path = _project_root_path / ".mf6minsim"
         build_mf6io_tex_example(
-            workspace_path=temp_path,
+            workspace_path=Path(temp),
             bin_path=bin_path,
-            example_model_path=examples_repo_path / "examples" / example_for_sample,
+            example_model_path=example_path,
         )
 
-    # build LaTeX file describing distribution folder structure
-    # build_tex_folder_structure(overwrite=True)
+    # build deprecations table for insertion into LaTex release notes
+    build_deprecations_tex()
 
     if not full:
         # convert LaTeX to PDF
-        build_pdfs_from_tex(tex_paths=_dev_dist_tex_paths, output_path=output_path)
+        build_pdfs_from_tex(tex_paths=_dev_dist_tex_paths, output_path=output_path, overwrite=overwrite)
     else:
         # convert benchmarks to LaTex, running them first if necessary
-        build_benchmark_tex(output_path=output_path, overwrite=overwrite)
+        build_benchmark_tex(
+            output_path=output_path, overwrite=overwrite, repo_owner=repo_owner
+        )
 
         # download example docs
-        latest = get_release("MODFLOW-USGS/modflow6-examples", "latest")
+        latest = get_release(f"{repo_owner}/modflow6-examples", "latest")
         assets = latest["assets"]
         asset = next(iter([a for a in assets if a["name"] == "mf6examples.pdf"]), None)
         download_and_unzip(asset["browser_download_url"], output_path, verbose=True)
@@ -529,13 +560,6 @@ def test_build_documentation(tmp_path):
             """
         ),
     )
-    parser.add_argument(
-        "-t",
-        "--tex-path",
-        action="append",
-        required=False,
-        help="Extra LaTeX files to include",
-    )
     parser.add_argument(
         "-b",
         "--bin-path",
@@ -544,18 +568,19 @@ def test_build_documentation(tmp_path):
         help="Location of modflow6 executables",
     )
     parser.add_argument(
-        "-e",
-        "--examples-repo-path",
+        "-f",
+        "--force",
         required=False,
-        default=str(_examples_repo_path),
-        help="Path to directory containing modflow6 example models",
+        default=False,
+        action="store_true",
+        help="Recreate and overwrite existing artifacts",
     )
     parser.add_argument(
-        "-s",
-        "--example-for-sample",
+        "--full",
         required=False,
-        default="ex-gwf-twri01",
-        help="Name of example model to use for sample mf6 output",
+        default=False,
+        action="store_true",
+        help="Build docs for a full rather than minimal distribution",
     )
     parser.add_argument(
         "-o",
@@ -565,35 +590,19 @@ def test_build_documentation(tmp_path):
         help="Location to create documentation artifacts",
     )
     parser.add_argument(
-        "--full",
+        "--repo-owner",
         required=False,
-        default=False,
-        action="store_true",
-        help="Build docs for a full rather than minimal distribution",
-    )
-    parser.add_argument(
-        "-f",
-        "--force",
-        required=False,
-        default=False,
-        action="store_true",
-        help="Recreate and overwrite existing artifacts",
+        default="MODFLOW-USGS",
+        help="Repository owner (substitute your own for a fork)",
     )
     args = parser.parse_args()
-    tex_paths = _full_dist_tex_paths + (
-        [Path(p) for p in args.tex_path] if args.tex_path else []
-    )
     output_path = Path(args.output_path).expanduser().absolute()
     output_path.mkdir(parents=True, exist_ok=True)
     bin_path = Path(args.bin_path).expanduser().absolute()
-    examples_repo_path = Path(args.examples_repo_path).expanduser().absolute()
-    example_for_sample = args.example_for_sample
-
     build_documentation(
         bin_path=bin_path,
-        output_path=output_path,
-        examples_repo_path=examples_repo_path,
-        example_for_sample=example_for_sample,
         full=args.full,
+        output_path=output_path,
         overwrite=args.force,
+        repo_owner=args.repo_owner,
     )
diff --git a/distribution/build_makefiles.py b/distribution/build_makefiles.py
index ce441200775..e9fb09645db 100644
--- a/distribution/build_makefiles.py
+++ b/distribution/build_makefiles.py
@@ -6,8 +6,8 @@
 import pymake
 import pytest
 from flaky import flaky
-from modflow_devtools.misc import set_dir
 from modflow_devtools.markers import requires_exe
+from modflow_devtools.misc import set_dir
 
 from utils import get_modified_time, get_project_root_path
 
diff --git a/distribution/check_dist.py b/distribution/check_dist.py
index 27be7d087bd..f8eab4355d6 100644
--- a/distribution/check_dist.py
+++ b/distribution/check_dist.py
@@ -1,5 +1,4 @@
 import platform
-import re
 import subprocess
 from os import environ
 from pathlib import Path
@@ -7,14 +6,34 @@
 
 import pytest
 
-from utils import split_nonnumeric
 
+# OS-specific extensions
 _system = platform.system()
 _eext = ".exe" if _system == "Windows" else ""
 _soext = ".dll" if _system == "Windows" else ".so" if _system == "Linux" else ".dylib"
 _scext = ".bat" if _system == "Windows" else ".sh"
+
+# fortran compiler
 _fc = environ.get("FC", None)
 
+# directories included in full distribution
+_included_dir_paths = {
+    "full": [
+        "bin",
+        "doc",
+        "examples",
+        "src",
+        "srcbmi",
+        "msvs",
+        "make",
+        "utils",
+    ],
+    "minimal": [
+        "bin",
+        "doc",
+    ],
+}
+
 
 @pytest.fixture
 def approved(request):
@@ -47,26 +66,41 @@ def skip():
     return path
 
 
-def test_sources(dist_dir_path, approved, releasemode, full):
+def test_directories(dist_dir_path, full):
+    for dir_path in _included_dir_paths["full" if full else "minimal"]:
+        assert (dist_dir_path / dir_path).is_dir()
+
+
+def test_sources(dist_dir_path, releasemode, full):
     if not full:
         pytest.skip(reason="sources not included in minimal distribution")
 
+    # check top-level meson files
+    assert (dist_dir_path / "meson.build").is_file()
+    assert (dist_dir_path / "meson.options").is_file()
+
+    # check src subdir
     assert (dist_dir_path / "src").is_dir()
     assert (dist_dir_path / "src" / "mf6.f90").is_file()
-
     version_file_path = dist_dir_path / "src" / "Utilities" / "version.f90"
     assert version_file_path.is_file()
 
-    # find IDEVELOPMODE line
+    # check IDEVELOPMODE
     lines = open(version_file_path, "r").read().splitlines()
     pattern = ":: IDEVELOPMODE ="
     line = next(iter([l for l in lines if pattern in l]), None)
     assert line
-
-    # make sure IDEVELOPMODE was set correctly
     idevelopmode = 0 if releasemode else 1
     assert f"IDEVELOPMODE = {idevelopmode}" in line
 
+    # check utils subdir
+    assert (dist_dir_path / "utils").is_dir()
+    assert (dist_dir_path / "utils" / "mf5to6").is_dir()
+    assert (dist_dir_path / "utils" / "zonebudget").is_dir()
+    assert (dist_dir_path / "utils" / "mf5to6" / "pymake").is_dir()
+    assert (dist_dir_path / "utils" / "zonebudget" / "pymake").is_dir()
+    assert not (dist_dir_path / "utils" / "idmloader").is_dir()
+
 
 @pytest.mark.skipif(not _fc, reason="needs Fortran compiler")
 def test_makefiles(dist_dir_path, full):
@@ -142,13 +176,13 @@ def test_examples(dist_dir_path, full):
     print(f"{len(example_paths)} example models found:")
     pprint(example_paths)
     for p in example_paths:
-        pprint(
-            subprocess.check_output([str(p / f"run{_scext}")], cwd=p).decode().split()
-        )
+        script_path = p / f"run{_scext}"
+        if not script_path.is_file():
+            continue
+        pprint(subprocess.check_output([str(script_path)], cwd=p).decode().split())
         break
 
 
-
 def test_binaries(dist_dir_path, approved):
     bin_path = dist_dir_path / "bin"
     assert (bin_path / f"mf6{_eext}").is_file()
@@ -156,19 +190,23 @@ def test_binaries(dist_dir_path, approved):
     assert (bin_path / f"mf5to6{_eext}").is_file()
     assert (bin_path / f"libmf6{_soext}").is_file()
 
+    # get version string
     output = " ".join(
         subprocess.check_output([str(bin_path / f"mf6{_eext}"), "-v"]).decode().split()
     ).lower()
     assert output.startswith("mf6")
 
-    # make sure binaries were built in correct mode
+    # make sure version string reflects approval
     assert ("preliminary" in output) != approved
 
-    # check version string
+    # check version numbers
     version = output.lower().split(" ")[1]
-    print(version)
+    print("Version string:", version)
     v_split = version.split(".")
-    assert len(v_split) == 3
-    assert all(s.isdigit() for s in v_split[:2])
-    sol = split_nonnumeric(v_split[2])
-    assert sol[0].isdigit()
+    assert len(v_split) >= 3
+
+    # approved release should use semantic version number with
+    # exactly 3 components and no alphabetic characters in it
+    if approved:
+        assert len(v_split) == 3
+        assert all(s.isdigit() for s in v_split[:3])
diff --git a/distribution/conftest.py b/distribution/conftest.py
index 860ef1d585b..df18401b2a4 100644
--- a/distribution/conftest.py
+++ b/distribution/conftest.py
@@ -1,11 +1,11 @@
 from pathlib import Path
 
-from update_version import Version
+from packaging.version import Version
 
 _project_root_path = Path(__file__).resolve().parent.parent
 _dist_dir_path = (
     _project_root_path.parent
-    / f"mf{str(Version.from_file(_project_root_path / 'version.txt'))}"
+    / f"mf{str(Version((_project_root_path / 'version.txt').read_text().strip()))}"
 )
 
 
diff --git a/distribution/update_version.py b/distribution/update_version.py
index f1112c58761..e09e0c69aef 100755
--- a/distribution/update_version.py
+++ b/distribution/update_version.py
@@ -31,20 +31,18 @@
 import argparse
 import json
 import os
-import re
-import shutil
 import textwrap
 from collections import OrderedDict
 from datetime import datetime
-from os import PathLike
+from packaging.version import Version
 from pathlib import Path
-from typing import NamedTuple, Optional
+from typing import Optional
 
 import pytest
 from filelock import FileLock
 import yaml
 
-from utils import get_modified_time, split_nonnumeric
+from utils import get_modified_time
 
 project_name = "MODFLOW 6"
 project_root_path = Path(__file__).resolve().parent.parent
@@ -62,56 +60,6 @@
 ]
 
 
-class Version(NamedTuple):
-    """Semantic version number, optionally with a short label (e.g, 'rc').
-    The label may contain numbers but must begin with a letter."""
-
-    major: int = 0
-    minor: int = 0
-    patch: int = 0
-    label: Optional[str] = None
-
-    def __repr__(self):
-        s = f"{self.major}.{self.minor}.{self.patch}"
-        if self.label is not None and self.label != "":
-            s += self.label
-        return s
-
-    @classmethod
-    def from_string(cls, version: str) -> "Version":
-        t = version.split(".")
-        assert len(t) > 2
-        vmajor = int(t[0])
-        vminor = int(t[1])
-        tt = split_nonnumeric(t[2])
-        vpatch = int(tt[0])
-        vlabel = tt[1] if len(tt) > 1 else None
-        return cls(major=vmajor, minor=vminor, patch=vpatch, label=vlabel)
-
-    @classmethod
-    def from_file(cls, path: PathLike) -> "Version":
-        path = Path(path).expanduser().absolute()
-        lines = [line.rstrip("\n") for line in open(Path(path), "r")]
-        vmajor = vminor = vpatch = vlabel = None
-        for line in lines:
-            t = line.split()
-            if "major =" in line:
-                vmajor = int(t[2])
-            elif "minor =" in line:
-                vminor = int(t[2])
-            elif "micro =" in line:
-                vpatch = int(t[2])
-            elif "label =" in line:
-                vlabel = t[2].replace("'", "")
-
-        msg = "version string must follow semantic version format, with optional label: major.minor.patch[label]"
-        missing = lambda v: f"Missing {v} number, {msg}"
-        assert vmajor is not None, missing("major")
-        assert vminor is not None, missing("minor")
-        assert vpatch is not None, missing("patch")
-        return cls(major=vmajor, minor=vminor, patch=vpatch, label=vlabel)
-
-
 _approved_fmtdisclaimer = '''  character(len=*), parameter :: FMTDISCLAIMER = &
     "(/,&
     &'This software has been approved for release by the U.S. Geological ',/,&
@@ -181,25 +129,17 @@ def log_update(path, version: Version):
 
 def update_version_txt_and_py(version: Version, timestamp: datetime):
     with open(version_file_path, "w") as f:
+        f.write(str(version))
+    log_update(version_file_path, version)
+
+    py_path = project_root_path / "doc" / version_file_path.name.replace(".txt", ".py")
+    with open(py_path, "w") as f:
         f.write(
             f"# {project_name} version file automatically "
             + f"created using...{os.path.basename(__file__)}\n"
         )
         f.write("# created on..." + f"{timestamp.strftime('%B %d, %Y %H:%M:%S')}\n")
-        f.write("\n")
-        f.write(f"major = {version.major}\n")
-        f.write(f"minor = {version.minor}\n")
-        f.write(f"micro = {version.patch}\n")
-        f.write(
-            "label = " + (("'" + version.label + "'") if version.label else "''") + "\n"
-        )
-        f.write("__version__ = '{:d}.{:d}.{:d}'.format(major, minor, micro)\n")
-        f.write("if label:\n")
-        f.write("\t__version__ += '{}{}'.format(__version__, label)")
-        f.close()
-    log_update(version_file_path, version)
-    py_path = project_root_path / "doc" / version_file_path.name.replace(".txt", ".py")
-    shutil.copyfile(version_file_path, py_path)
+        f.write(f'__version__ = "{version}"\n')
     log_update(py_path, version)
 
 
@@ -209,7 +149,7 @@ def update_meson_build(version: Version):
     with open(path, "w") as f:
         for line in lines:
             if "version:" in line and "meson_version:" not in line:
-                line = f"  version: '{version.major}.{version.minor}.{version.patch}{version.label if version.label else ''}',"
+                line = f"  version: '{version}',"
             f.write(f"{line}\n")
     log_update(path, version)
 
@@ -217,7 +157,7 @@ def update_meson_build(version: Version):
 def update_version_tex(version: Version, timestamp: datetime):
     path = project_root_path / "doc" / "version.tex"
     with open(path, "w") as f:
-        line = "\\newcommand{\\modflowversion}{mf" + f"{str(version)}" + "}"
+        line = "\\newcommand{\\modflowversion}{mf" + str(version) + "}"
         f.write(f"{line}\n")
         line = (
             "\\newcommand{\\modflowdate}{" + f"{timestamp.strftime('%B %d, %Y')}" + "}"
@@ -351,11 +291,11 @@ def update_version(
     lock_path = Path(version_file_path.name + ".lock")
     try:
         lock = FileLock(lock_path)
-        previous = Version.from_file(version_file_path)
+        previous = Version(version_file_path.read_text().strip())
         version = (
             version
             if version
-            else Version(previous.major, previous.minor, previous.patch)
+            else previous
         )
 
         with lock:
@@ -370,8 +310,8 @@ def update_version(
         lock_path.unlink(missing_ok=True)
 
 
-_initial_version = Version(0, 0, 1)
-_current_version = Version.from_file(version_file_path)
+_initial_version = Version("0.0.1")
+_current_version = Version(version_file_path.read_text().strip())
 
 
 @pytest.mark.skip(reason="reverts repo files on cleanup, tread carefully")
@@ -379,17 +319,8 @@ def update_version(
     "version",
     [
         None,
-        Version(
-            major=_initial_version.major,
-            minor=_initial_version.minor,
-            patch=_initial_version.patch,
-        ),
-        Version(
-            major=_initial_version.major,
-            minor=_initial_version.minor,
-            patch=_initial_version.patch,
-            label="rc",
-        ),
+        _initial_version,
+        Version(f"{_initial_version.major}.{_initial_version.minor}.dev{_initial_version.micro}"),
     ],
 )
 @pytest.mark.parametrize("approved", [True, False])
@@ -405,7 +336,7 @@ def test_update_version(version, approved, developmode):
             approved=approved,
             developmode=developmode,
         )
-        updated = Version.from_file(version_file_path)
+        updated = Version(version_file_path.read_text().strip())
 
         # check files containing version info were modified
         for p, t in zip(touched_file_paths, m_times):
@@ -414,20 +345,10 @@ def test_update_version(version, approved, developmode):
         # check version number and optional label are correct
         if version:
             # version should be auto-incremented
-            assert updated.major == _initial_version.major
-            assert updated.minor == _initial_version.minor
-            assert updated.patch == _initial_version.patch
-            if version.label is not None:
-                assert updated.label == version.label
+            assert updated == _initial_version
         else:
             # version should not have changed
-            assert updated.major == _current_version.major
-            assert updated.minor == _current_version.minor
-            assert updated.patch == _current_version.patch
-            if version.label is not None:
-                assert updated.label == version.label
-        if version.label is not None:
-            assert updated.label == _initial_version
+            assert updated == _current_version
 
         # check IDEVELOPMODE was set correctly
         version_f90_path = project_root_path / "src" / "Utilities" / "version.f90"
@@ -462,13 +383,10 @@ def test_update_version(version, approved, developmode):
             provided, the version number will not be changed. A file lock is held
             to synchronize file access. To indicate a version is production-ready
             use --approve. This will change the disclaimer and version tag label,
-            removing 'Release Candidate' from the latter and modifying the former
-            to reflect approval The IDEVELOPMODE flag is set to 1 for preliminary
-            versions and 0 for approved versions. The version tag must follow the
+            removing '(preliminary)' from the latter, and modifying the former to
+            reflect approval The --releasemode flag controls whether IDEVELOPMODE
+            is set to 0 instead of the default 1. The version tag must follow the
             '<major>.<minor>.<patch>' format conventions for semantic versioning.
-            If --version is provided, --bump-patch, --bump-minor and --bump-major
-            may not be provided. Likewise, if any of the latter are provided, the
-            version number must not be specified.
             """
         ),
     )
@@ -492,24 +410,6 @@ def test_update_version(version, approved, developmode):
         action="store_true",
         help="Set IDEVELOPMODE to 0 for release mode (defaults to false for development distributions)",
     )
-    parser.add_argument(
-        "--bump-major",
-        required=False,
-        action="store_true",
-        help="Increment the major version number (cannot be used with --version, defaults to false)",
-    )
-    parser.add_argument(
-        "--bump-minor",
-        required=False,
-        action="store_true",
-        help="Increment the minor version number (cannot be used with --version, defaults to false)",
-    )
-    parser.add_argument(
-        "--bump-patch",
-        required=False,
-        action="store_true",
-        help="Increment the patch version number (cannot be used with --version, defaults to false)",
-    )
     parser.add_argument(
         "-g",
         "--get",
@@ -518,33 +418,13 @@ def test_update_version(version, approved, developmode):
         help="Get the current version number, don't update anything (defaults to false)",
     )
     args = parser.parse_args()
-
-    if args.version and (args.bump_major or args.bump_minor or args.bump_patch):
-        raise ValueError(f"Cannot specify --version and --bump-*, use one or the other")
-
-    bump_flags = [b for b in [args.bump_major, args.bump_minor, args.bump_patch] if b]
-    if len(bump_flags) > 1:
-        raise ValueError(f"Cannot specify more than one --bump-* flag, use just one")
-
     if args.get:
-        print(Version.from_file(project_root_path / "version.txt"))
+        print(Version((project_root_path / "version.txt").read_text().strip()))
     else:
-        if not args.version and not any(bump_flags):
-            version = _current_version
-        elif args.version:
-            version = Version.from_string(args.version)
-        else:
-            current = Version.from_file(project_root_path / "version.txt")
-            if args.bump_major:
-                print(f"Incrementing major number")
-                version = Version(current.major + 1, 0, 0)
-            elif args.bump_minor:
-                print(f"Incrementing minor number")
-                version = Version(current.major, current.minor + 1, 0)
-            else:
-                print(f"Incrementing patch number")
-                version = Version(current.major, current.minor, current.patch + 1)
-
+        print(f"Updating to version {args.version} with options")
+        print(f"    releasemode: {args.releasemode}")
+        print(f"    approved: {args.approved}")
+        version = Version(args.version) if args.version else _current_version
         update_version(
             version=version,
             timestamp=datetime.now(),
diff --git a/doc/Common/gwf-lakobs.tex b/doc/Common/gwf-lakobs.tex
index 6686e6f650f..36efa37f01a 100644
--- a/doc/Common/gwf-lakobs.tex
+++ b/doc/Common/gwf-lakobs.tex
@@ -1,19 +1,19 @@
-LAK & stage & lakeno or boundname & -- & Surface-water stage in a lake. If boundname is specified, boundname must be unique for each lake. \\
-LAK & ext-inflow & lakeno or boundname & -- & Specified inflow into a lake or group of lakes. \\
-LAK & outlet-inflow & lakeno or boundname & -- & Simulated inflow from upstream lake outlets into a lake or group of lakes. \\
-LAK & inflow & lakeno or boundname & -- & Sum of specified inflow and simulated inflow from upstream lake outlets into a lake or group of lakes. \\
-LAK & from-mvr & lakeno or boundname & -- & Inflow into a lake or group of lakes from the MVR package. \\
-LAK & rainfall & lakeno or boundname & -- & Rainfall rate applied to a lake or group of lakes. \\
-LAK & runoff & lakeno or boundname & -- & Runoff rate applied to a lake or group of lakes. \\
-LAK & lak & lakeno or boundname & \texttt{iconn} or -- & Simulated flow rate for a lake or group of lakes and its aquifer connection(s). If boundname is not specified for ID, then the simulated lake-aquifer flow rate at a specific lake connection is observed. In this case, ID2 must be specified and is the connection number \texttt{iconn}. \\
-LAK & withdrawal & lakeno or boundname & -- & Specified withdrawal rate from a lake or group of lakes. \\
-LAK & evaporation & lakeno or boundname & -- & Simulated evaporation rate from a lake or group of lakes. \\
+LAK & stage & ifno or boundname & -- & Surface-water stage in a lake. If boundname is specified, boundname must be unique for each lake. \\
+LAK & ext-inflow & ifno or boundname & -- & Specified inflow into a lake or group of lakes. \\
+LAK & outlet-inflow & ifno or boundname & -- & Simulated inflow from upstream lake outlets into a lake or group of lakes. \\
+LAK & inflow & ifno or boundname & -- & Sum of specified inflow and simulated inflow from upstream lake outlets into a lake or group of lakes. \\
+LAK & from-mvr & ifno or boundname & -- & Inflow into a lake or group of lakes from the MVR package. \\
+LAK & rainfall & ifno or boundname & -- & Rainfall rate applied to a lake or group of lakes. \\
+LAK & runoff & ifno or boundname & -- & Runoff rate applied to a lake or group of lakes. \\
+LAK & lak & ifno or boundname & \texttt{iconn} or -- & Simulated flow rate for a lake or group of lakes and its aquifer connection(s). If boundname is not specified for ID, then the simulated lake-aquifer flow rate at a specific lake connection is observed. In this case, ID2 must be specified and is the connection number \texttt{iconn}. \\
+LAK & withdrawal & ifno or boundname & -- & Specified withdrawal rate from a lake or group of lakes. \\
+LAK & evaporation & ifno or boundname & -- & Simulated evaporation rate from a lake or group of lakes. \\
 LAK & ext-outflow & outletno or boundname & -- & External outflow from a lake outlet, a lake, or a group of lakes to an external boundary. If boundname is not specified for ID, then the external outflow from a specific lake outlet is observed. In this case, ID is the outlet number outletno. \\
 LAK & to-mvr & outletno or boundname & -- & Outflow from a lake outlet, a lake, or a group of lakes that is available for the MVR package. If boundname is not specified for ID, then the outflow available for the MVR package from a specific lake outlet is observed. In this case, ID is the outlet number outletno. \\
-LAK & storage & lakeno or boundname & -- & Simulated storage flow rate for a lake or group of lakes. \\
-LAK & constant & lakeno or boundname & -- & Simulated constant-flow rate for a lake or group of lakes. \\
+LAK & storage & ifno or boundname & -- & Simulated storage flow rate for a lake or group of lakes. \\
+LAK & constant & ifno or boundname & -- & Simulated constant-flow rate for a lake or group of lakes. \\
 LAK & outlet & outletno or boundname & -- & Simulated outlet flow rate from a lake outlet, a lake, or a group of lakes. If boundname is not specified for ID, then the flow from a specific lake outlet is observed. In this case, ID is the outlet number outletno. \\
-LAK & volume & lakeno or boundname & -- & Simulated lake volume or group of lakes. \\
-LAK & surface-area & lakeno or boundname & -- & Simulated surface area for a lake or group of lakes. \\
-LAK & wetted-area & lakeno or boundname & \texttt{iconn} or -- & Simulated wetted-area for a lake or group of lakes and its aquifer connection(s). If boundname is not specified for ID, then the wetted area of a specific lake connection is observed. In this case, ID2 must be specified and is the connection number \texttt{iconn}. \\
-LAK & conductance & lakeno or boundname & \texttt{iconn} or -- & Calculated conductance for a lake or group of lakes and its aquifer connection(s). If boundname is not specified for ID, then the calculated conductance of a specific lake connection is observed. In this case, ID2 must be specified and is the connection number \texttt{iconn}.
+LAK & volume & ifno or boundname & -- & Simulated lake volume or group of lakes. \\
+LAK & surface-area & ifno or boundname & -- & Simulated surface area for a lake or group of lakes. \\
+LAK & wetted-area & ifno or boundname & \texttt{iconn} or -- & Simulated wetted-area for a lake or group of lakes and its aquifer connection(s). If boundname is not specified for ID, then the wetted area of a specific lake connection is observed. In this case, ID2 must be specified and is the connection number \texttt{iconn}. \\
+LAK & conductance & ifno or boundname & \texttt{iconn} or -- & Calculated conductance for a lake or group of lakes and its aquifer connection(s). If boundname is not specified for ID, then the calculated conductance of a specific lake connection is observed. In this case, ID2 must be specified and is the connection number \texttt{iconn}.
diff --git a/doc/Common/gwf-mawobs.tex b/doc/Common/gwf-mawobs.tex
index 74f2bac793d..a98a4f1cca5 100644
--- a/doc/Common/gwf-mawobs.tex
+++ b/doc/Common/gwf-mawobs.tex
@@ -1,11 +1,11 @@
-MAW & head & wellno or boundname & -- & Head in a multi-aquifer well. If boundname is specified, boundname must be unique for each multi-aquifer well. \\
-MAW & from-mvr & wellno or boundname & -- & Simulated inflow to a well from the MVR package for a multi-aquifer well or a group of multi-aquifer wells. \\
-MAW & maw & wellno or boundname & \texttt{icon} or -- & Simulated flow rate for a multi-aquifer well or a group of multi-aquifer wells and its aquifer connection(s). If boundname is not specified for ID, then the simulated multi-aquifer well-aquifer flow rate at a specific multi-aquifer well connection is observed. In this case, ID2 must be specified and is the connection number \texttt{icon}. \\
-MAW & rate & wellno or boundname & -- & Simulated pumping rate for a multi-aquifer well or a group of multi-aquifer wells. \\
-MAW & rate-to-mvr & wellno or boundname & -- & Simulated well discharge that is available for the MVR package for a multi-aquifer well or a group of multi-aquifer wells. \\
-MAW & fw-rate & wellno or boundname & -- & Simulated flowing well flow rate for a multi-aquifer well or a group of multi-aquifer wells.  \\
-MAW & fw-to-mvr & wellno or boundname & -- & Simulated flowing well discharge rate that is available for the MVR package for a multi-aquifer well or a group of multi-aquifer wells. \\
-MAW & storage & wellno or boundname & -- & Simulated storage flow rate for a multi-aquifer well or a group of multi-aquifer wells. \\
-MAW & constant & wellno or boundname & -- & Simulated constant-flow rate for a multi-aquifer well or a group of multi-aquifer wells. \\
-MAW & conductance & wellno or boundname & \texttt{icon} or -- & Simulated well conductance for a multi-aquifer well or a group of multi-aquifer wells and its aquifer connection(s). If boundname is not specified for ID, then the simulated multi-aquifer well conductance at a specific multi-aquifer well connection is observed. In this case, ID2 must be specified and is the connection number \texttt{icon}. \\
-MAW & fw-conductance & wellno or boundname & -- & Simulated flowing well conductance for a multi-aquifer well or a group of multi-aquifer wells.
\ No newline at end of file
+MAW & head & ifno or boundname & -- & Head in a multi-aquifer well. If boundname is specified, boundname must be unique for each multi-aquifer well. \\
+MAW & from-mvr & ifno or boundname & -- & Simulated inflow to a well from the MVR package for a multi-aquifer well or a group of multi-aquifer wells. \\
+MAW & maw & ifno or boundname & \texttt{icon} or -- & Simulated flow rate for a multi-aquifer well or a group of multi-aquifer wells and its aquifer connection(s). If boundname is not specified for ID, then the simulated multi-aquifer well-aquifer flow rate at a specific multi-aquifer well connection is observed. In this case, ID2 must be specified and is the connection number \texttt{icon}. \\
+MAW & rate & ifno or boundname & -- & Simulated pumping rate for a multi-aquifer well or a group of multi-aquifer wells. \\
+MAW & rate-to-mvr & ifno or boundname & -- & Simulated well discharge that is available for the MVR package for a multi-aquifer well or a group of multi-aquifer wells. \\
+MAW & fw-rate & ifno or boundname & -- & Simulated flowing well flow rate for a multi-aquifer well or a group of multi-aquifer wells.  \\
+MAW & fw-to-mvr & ifno or boundname & -- & Simulated flowing well discharge rate that is available for the MVR package for a multi-aquifer well or a group of multi-aquifer wells. \\
+MAW & storage & ifno or boundname & -- & Simulated storage flow rate for a multi-aquifer well or a group of multi-aquifer wells. \\
+MAW & constant & ifno or boundname & -- & Simulated constant-flow rate for a multi-aquifer well or a group of multi-aquifer wells. \\
+MAW & conductance & ifno or boundname & \texttt{icon} or -- & Simulated well conductance for a multi-aquifer well or a group of multi-aquifer wells and its aquifer connection(s). If boundname is not specified for ID, then the simulated multi-aquifer well conductance at a specific multi-aquifer well connection is observed. In this case, ID2 must be specified and is the connection number \texttt{icon}. \\
+MAW & fw-conductance & ifno or boundname & -- & Simulated flowing well conductance for a multi-aquifer well or a group of multi-aquifer wells.
\ No newline at end of file
diff --git a/doc/Common/gwf-sfrobs.tex b/doc/Common/gwf-sfrobs.tex
index c8e447c2035..e67791f2635 100644
--- a/doc/Common/gwf-sfrobs.tex
+++ b/doc/Common/gwf-sfrobs.tex
@@ -1,18 +1,18 @@
-SFR & stage & rno or boundname & -- & Surface-water stage in a stream-reach boundary. If boundname is specified, boundname must be unique for each reach. \\
-SFR & ext-inflow & rno or boundname & -- & Inflow into a stream-reach from an external boundary for a stream-reach or a group of stream-reaches. \\
-SFR & inflow & rno or boundname & -- & Inflow into a stream-reach from upstream reaches for a stream-reach or a group of stream-reaches. \\
-SFR & from-mvr & rno or boundname & -- & Inflow into a stream-reach from the MVR package for a stream-reach or a group of stream-reaches. \\
-SFR & rainfall & rno or boundname & -- & Rainfall rate applied to a stream-reach or a group of stream-reaches. \\
-SFR & runoff & rno or boundname & -- & Runoff rate applied to a stream-reach or a group of stream-reaches. \\
-SFR & sfr & rno or boundname & -- & Simulated flow rate for a stream-reach and its aquifer connection for a stream-reach or a group of stream-reaches. \\
-SFR & evaporation & rno or boundname & -- & Simulated evaporation rate from a stream-reach or a group of stream-reaches. \\
-SFR & outflow & rno or boundname & -- & Outflow from a stream-reach to downstream reaches for a stream-reach or a group of stream-reaches. \\
-SFR & ext-outflow & rno or boundname & -- & Outflow from a stream-reach to an external boundary for a stream-reach or a group of stream-reaches. \\
-SFR & to-mvr & rno or boundname & -- & Outflow from a stream-reach that is available for the MVR package for a stream-reach or a group of stream-reaches. \\
-SFR & upstream-flow & rno or boundname & -- & Upstream flow for a stream-reach or a group of stream-reaches from upstream reaches and the MVR package. \\
-SFR & downstream-flow & rno or boundname & -- & Downstream flow for a stream-reach or a group of stream-reaches prior to diversions and the MVR package. \\
-SFR & depth & rno or boundname & -- & Surface-water depth in a stream-reach boundary. If boundname is specified, boundname must be unique for each reach. \\
-SFR & wet-perimeter & rno or boundname & -- & Wetted perimeter in a stream-reach boundary. If boundname is specified, boundname must be unique for each reach. \\
-SFR & wet-area & rno or boundname & -- & Wetted cross-section area in a stream-reach boundary. If boundname is specified, boundname must be unique for each reach. \\
-SFR & wet-width & rno or boundname & -- & Wetted top width in a stream-reach boundary. If boundname is specified, boundname must be unique for each reach. \\
+SFR & stage & ifno or boundname & -- & Surface-water stage in a stream-reach boundary. If boundname is specified, boundname must be unique for each reach. \\
+SFR & ext-inflow & ifno or boundname & -- & Inflow into a stream-reach from an external boundary for a stream-reach or a group of stream-reaches. \\
+SFR & inflow & ifno or boundname & -- & Inflow into a stream-reach from upstream reaches for a stream-reach or a group of stream-reaches. \\
+SFR & from-mvr & ifno or boundname & -- & Inflow into a stream-reach from the MVR package for a stream-reach or a group of stream-reaches. \\
+SFR & rainfall & ifno or boundname & -- & Rainfall rate applied to a stream-reach or a group of stream-reaches. \\
+SFR & runoff & ifno or boundname & -- & Runoff rate applied to a stream-reach or a group of stream-reaches. \\
+SFR & sfr & ifno or boundname & -- & Simulated flow rate for a stream-reach and its aquifer connection for a stream-reach or a group of stream-reaches. \\
+SFR & evaporation & ifno or boundname & -- & Simulated evaporation rate from a stream-reach or a group of stream-reaches. \\
+SFR & outflow & ifno or boundname & -- & Outflow from a stream-reach to downstream reaches for a stream-reach or a group of stream-reaches. \\
+SFR & ext-outflow & ifno or boundname & -- & Outflow from a stream-reach to an external boundary for a stream-reach or a group of stream-reaches. \\
+SFR & to-mvr & ifno or boundname & -- & Outflow from a stream-reach that is available for the MVR package for a stream-reach or a group of stream-reaches. \\
+SFR & upstream-flow & ifno or boundname & -- & Upstream flow for a stream-reach or a group of stream-reaches from upstream reaches and the MVR package. \\
+SFR & downstream-flow & ifno or boundname & -- & Downstream flow for a stream-reach or a group of stream-reaches prior to diversions and the MVR package. \\
+SFR & depth & ifno or boundname & -- & Surface-water depth in a stream-reach boundary. If boundname is specified, boundname must be unique for each reach. \\
+SFR & wet-perimeter & ifno or boundname & -- & Wetted perimeter in a stream-reach boundary. If boundname is specified, boundname must be unique for each reach. \\
+SFR & wet-area & ifno or boundname & -- & Wetted cross-section area in a stream-reach boundary. If boundname is specified, boundname must be unique for each reach. \\
+SFR & wet-width & ifno or boundname & -- & Wetted top width in a stream-reach boundary. If boundname is specified, boundname must be unique for each reach. \\
 
diff --git a/doc/Common/gwf-uzfobs.tex b/doc/Common/gwf-uzfobs.tex
index b69b947ae86..abe1a42bd9f 100644
--- a/doc/Common/gwf-uzfobs.tex
+++ b/doc/Common/gwf-uzfobs.tex
@@ -1,12 +1,12 @@
-UZF & uzf-gwrch & iuzno or boundname & -- & Simulated recharge to the aquifer calculated by the UZF package for a UZF cell or a group of UZF cells.\\
-UZF & uzf-gwd & iuzno or boundname & -- & Simulated groundwater discharge to the land surface calculated by the UZF package for a UZF cell or a group of UZF cells. \\
-UZF & uzf-gwd-to-mvr & iuzno or boundname & -- & Simulated groundwater discharge to the land surface calculated by the UZF package that is available to the MVR package for a UZF cell or a group of UZF cells. \\
-UZF & uzf-gwet & iuzno or boundname & -- & Simulated groundwater evapotranspiration calculated by the UZF package for a UZF cell or a group of UZF cells.\\
-UZF & infiltration & iuzno or boundname & -- & Specified infiltration rate applied to a UZF package for a UZF cell or a group of UZF cells with landflag values not equal to zero.\\
-UZF & from-mvr & iuzno or boundname & -- & Inflow into a UZF cell from the MVR package for a UZF cell or a group of UZF cells. \\
-UZF & rej-inf & iuzno or boundname & -- & Simulated rejected infiltration calculated by the UZF package for a UZF cell or a group of UZF cells. \\
-UZF & rej-inf-to-mvr & iuzno or boundname & -- & Simulated rejected infiltration calculated by the UZF package that is available to the MVR package for a UZF cell or a group of UZF cells. \\
-UZF & uzet & iuzno or boundname & -- & Simulated unsaturated evapotranspiration calculated by the UZF package for a UZF cell or a group of UZF cells.\\
-UZF & storage & iuzno or boundname & -- & Simulated storage flow rate for a UZF package cell or a group of UZF cells. \\
-UZF & net-infiltration & iuzno or boundname & -- & Simulated net infiltration rate for a UZF package cell or a group of UZF cells. \\
-UZF & water-content & iuzno or boundname & depth & Unsaturated-zone water content at a user-specified depth (ID2) relative to the top of GWF cellid for a UZF cell. The user-specified depth must be greater than or equal to zero and less than the thickness of GWF cellid (TOP - BOT). If boundname is specified, boundname must be unique for each UZF cell.
\ No newline at end of file
+UZF & uzf-gwrch & ifno or boundname & -- & Simulated recharge to the aquifer calculated by the UZF package for a UZF cell or a group of UZF cells.\\
+UZF & uzf-gwd & ifno or boundname & -- & Simulated groundwater discharge to the land surface calculated by the UZF package for a UZF cell or a group of UZF cells. \\
+UZF & uzf-gwd-to-mvr & ifno or boundname & -- & Simulated groundwater discharge to the land surface calculated by the UZF package that is available to the MVR package for a UZF cell or a group of UZF cells. \\
+UZF & uzf-gwet & ifno or boundname & -- & Simulated groundwater evapotranspiration calculated by the UZF package for a UZF cell or a group of UZF cells.\\
+UZF & infiltration & ifno or boundname & -- & Specified infiltration rate applied to a UZF package for a UZF cell or a group of UZF cells with landflag values not equal to zero.\\
+UZF & from-mvr & ifno or boundname & -- & Inflow into a UZF cell from the MVR package for a UZF cell or a group of UZF cells. \\
+UZF & rej-inf & ifno or boundname & -- & Simulated rejected infiltration calculated by the UZF package for a UZF cell or a group of UZF cells. \\
+UZF & rej-inf-to-mvr & ifno or boundname & -- & Simulated rejected infiltration calculated by the UZF package that is available to the MVR package for a UZF cell or a group of UZF cells. \\
+UZF & uzet & ifno or boundname & -- & Simulated unsaturated evapotranspiration calculated by the UZF package for a UZF cell or a group of UZF cells.\\
+UZF & storage & ifno or boundname & -- & Simulated storage flow rate for a UZF package cell or a group of UZF cells. \\
+UZF & net-infiltration & ifno or boundname & -- & Simulated net infiltration rate for a UZF package cell or a group of UZF cells. \\
+UZF & water-content & ifno or boundname & depth & Unsaturated-zone water content at a user-specified depth (ID2) relative to the top of GWF cellid for a UZF cell. The user-specified depth must be greater than or equal to zero and less than the thickness of GWF cellid (TOP - BOT). If boundname is specified, boundname must be unique for each UZF cell.
\ No newline at end of file
diff --git a/doc/Common/gwt-lktobs.tex b/doc/Common/gwt-lktobs.tex
index 637dbcf3d49..7d5279fa655 100644
--- a/doc/Common/gwt-lktobs.tex
+++ b/doc/Common/gwt-lktobs.tex
@@ -1,25 +1,25 @@
 % general APT observations
-LKT & concentration & lakeno or boundname & -- & Lake concentration. If boundname is specified, boundname must be unique for each lake. \\
-LKT & flow-ja-face & lakeno or boundname & lakeno or -- & Mass flow between two lakes connected by an outlet.  If more than one outlet is used to connect the same two lakes, then the mass flow for only the first outlet can be observed.  If a boundname is specified for ID1, then the result is the total mass flow for all outlets for a lake. If a boundname is specified for ID1 then ID2 is not used.\\
-LKT & storage & lakeno or boundname & -- & Simulated mass storage flow rate for a lake or group of lakes. \\
-LKT & constant & lakeno or boundname & -- & Simulated mass constant-flow rate for a lake or group of lakes. \\
-LKT & from-mvr & lakeno or boundname & -- & Simulated mass inflow into a lake or group of lakes from the MVT package. Mass inflow is calculated as the product of provider concentration and the mover flow rate. \\
+LKT & concentration & ifno or boundname & -- & Lake concentration. If boundname is specified, boundname must be unique for each lake. \\
+LKT & flow-ja-face & ifno or boundname & ifno or -- & Mass flow between two lakes connected by an outlet.  If more than one outlet is used to connect the same two lakes, then the mass flow for only the first outlet can be observed.  If a boundname is specified for ID1, then the result is the total mass flow for all outlets for a lake. If a boundname is specified for ID1 then ID2 is not used.\\
+LKT & storage & ifno or boundname & -- & Simulated mass storage flow rate for a lake or group of lakes. \\
+LKT & constant & ifno or boundname & -- & Simulated mass constant-flow rate for a lake or group of lakes. \\
+LKT & from-mvr & ifno or boundname & -- & Simulated mass inflow into a lake or group of lakes from the MVT package. Mass inflow is calculated as the product of provider concentration and the mover flow rate. \\
 LKT & to-mvr & outletno or boundname & -- & Mass outflow from a lake outlet, a lake, or a group of lakes that is available for the MVR package. If boundname is not specified for ID, then the outflow available for the MVR package from a specific lake outlet is observed. In this case, ID is the outlet number, which must be between 1 and NOUTLETS. \\
-LKT & lkt & lakeno or boundname & \texttt{iconn} or -- & Mass flow rate for a lake or group of lakes and its aquifer connection(s). If boundname is not specified for ID, then the simulated lake-aquifer flow rate at a specific lake connection is observed. In this case, ID2 must be specified and is the connection number \texttt{iconn} for lake \texttt{lakeno}. \\
+LKT & lkt & ifno or boundname & \texttt{iconn} or -- & Mass flow rate for a lake or group of lakes and its aquifer connection(s). If boundname is not specified for ID, then the simulated lake-aquifer flow rate at a specific lake connection is observed. In this case, ID2 must be specified and is the connection number \texttt{iconn} for lake \texttt{ifno}. \\
 
 %observations specific to the lake package
 % rainfall evaporation runoff ext-inflow withdrawal outflow
-LKT & rainfall & lakeno or boundname & -- & Rainfall rate applied to a lake or group of lakes multiplied by the rainfall concentration. \\
-LKT & evaporation & lakeno or boundname & -- & Simulated evaporation rate from a lake or group of lakes multiplied by the evaporation concentration. \\
-LKT & runoff & lakeno or boundname & -- & Runoff rate applied to a lake or group of lakes multiplied by the runoff concentration. \\
-LKT & ext-inflow & lakeno or boundname & -- & Mass inflow into a lake or group of lakes calculated as the external inflow rate multiplied by the inflow concentration. \\
-LKT & withdrawal & lakeno or boundname & -- & Specified withdrawal rate from a lake or group of lakes multiplied by the simulated lake concentration. \\
-LKT & ext-outflow & lakeno or boundname & -- & External outflow from a lake or a group of lakes, through their outlets, to an external boundary.  If the water mover is active, the reported ext-outflow value plus the rate to mover is equal to the total outlet outflow.
+LKT & rainfall & ifno or boundname & -- & Rainfall rate applied to a lake or group of lakes multiplied by the rainfall concentration. \\
+LKT & evaporation & ifno or boundname & -- & Simulated evaporation rate from a lake or group of lakes multiplied by the evaporation concentration. \\
+LKT & runoff & ifno or boundname & -- & Runoff rate applied to a lake or group of lakes multiplied by the runoff concentration. \\
+LKT & ext-inflow & ifno or boundname & -- & Mass inflow into a lake or group of lakes calculated as the external inflow rate multiplied by the inflow concentration. \\
+LKT & withdrawal & ifno or boundname & -- & Specified withdrawal rate from a lake or group of lakes multiplied by the simulated lake concentration. \\
+LKT & ext-outflow & ifno or boundname & -- & External outflow from a lake or a group of lakes, through their outlets, to an external boundary.  If the water mover is active, the reported ext-outflow value plus the rate to mover is equal to the total outlet outflow.
 
-%LKT & outlet-inflow & lakeno or boundname & -- & Simulated inflow from upstream lake outlets into a lake or group of lakes. \\
-%LKT & inflow & lakeno or boundname & -- & Sum of specified inflow and simulated inflow from upstream lake outlets into a lake or group of lakes. \\
+%LKT & outlet-inflow & ifno or boundname & -- & Simulated inflow from upstream lake outlets into a lake or group of lakes. \\
+%LKT & inflow & ifno or boundname & -- & Sum of specified inflow and simulated inflow from upstream lake outlets into a lake or group of lakes. \\
 %LKT & outlet & outletno or boundname & -- & Simulate outlet flow rate from a lake outlet, a lake, or a group of lakes. If boundname is not specified for ID, then the flow from a specific lake outlet is observed. In this case, ID is the outlet number outletno. \\
-%LKT & volume & lakeno or boundname & -- & Simulated lake volume or group of lakes. \\
-%LKT & surface-area & lakeno or boundname & -- & Simulated surface area for a lake or group of lakes. \\
-%LKT & wetted-area & lakeno or boundname & \texttt{iconn} or -- & Simulated wetted-area for a lake or group of lakes and its aquifer connection(s). If boundname is not specified for ID, then the wetted area of a specific lake connection is observed. In this case, ID2 must be specified and is the connection number \texttt{iconn}. \\
-%LKT & conductance & lakeno or boundname & \texttt{iconn} or -- & Calculated conductance for a lake or group of lakes and its aquifer connection(s). If boundname is not specified for ID, then the calculated conductance of a specific lake connection is observed. In this case, ID2 must be specified and is the connection number \texttt{iconn}.
+%LKT & volume & ifno or boundname & -- & Simulated lake volume or group of lakes. \\
+%LKT & surface-area & ifno or boundname & -- & Simulated surface area for a lake or group of lakes. \\
+%LKT & wetted-area & ifno or boundname & \texttt{iconn} or -- & Simulated wetted-area for a lake or group of lakes and its aquifer connection(s). If boundname is not specified for ID, then the wetted area of a specific lake connection is observed. In this case, ID2 must be specified and is the connection number \texttt{iconn}. \\
+%LKT & conductance & ifno or boundname & \texttt{iconn} or -- & Calculated conductance for a lake or group of lakes and its aquifer connection(s). If boundname is not specified for ID, then the calculated conductance of a specific lake connection is observed. In this case, ID2 must be specified and is the connection number \texttt{iconn}.
diff --git a/doc/Common/gwt-mwtobs.tex b/doc/Common/gwt-mwtobs.tex
index d05c267ba37..9799a090edc 100644
--- a/doc/Common/gwt-mwtobs.tex
+++ b/doc/Common/gwt-mwtobs.tex
@@ -1,13 +1,13 @@
 % general APT observations
-MWT & concentration & mawno or boundname & -- & Well concentration. If boundname is specified, boundname must be unique for each well. \\
+MWT & concentration & ifno or boundname & -- & Well concentration. If boundname is specified, boundname must be unique for each well. \\
 %flowjaface not included
-MWT & storage & mawno or boundname & -- & Simulated mass storage flow rate for a well or group of wells. \\
-MWT & constant & mawno or boundname & -- & Simulated mass constant-flow rate for a well or group of wells. \\
-MWT & from-mvr & mawno or boundname & -- & Simulated mass inflow into a well or group of wells from the MVT package. Mass inflow is calculated as the product of provider concentration and the mover flow rate. \\
-MWT & mwt & mawno or boundname & \texttt{iconn} or -- & Mass flow rate for a well or group of wells and its aquifer connection(s). If boundname is not specified for ID, then the simulated well-aquifer flow rate at a specific well connection is observed. In this case, ID2 must be specified and is the connection number \texttt{iconn} for well \texttt{mawno}. \\
+MWT & storage & ifno or boundname & -- & Simulated mass storage flow rate for a well or group of wells. \\
+MWT & constant & ifno or boundname & -- & Simulated mass constant-flow rate for a well or group of wells. \\
+MWT & from-mvr & ifno or boundname & -- & Simulated mass inflow into a well or group of wells from the MVT package. Mass inflow is calculated as the product of provider concentration and the mover flow rate. \\
+MWT & mwt & ifno or boundname & \texttt{iconn} or -- & Mass flow rate for a well or group of wells and its aquifer connection(s). If boundname is not specified for ID, then the simulated well-aquifer flow rate at a specific well connection is observed. In this case, ID2 must be specified and is the connection number \texttt{iconn} for well \texttt{ifno}. \\
 
 % observations specific to the mwt package
-MWT & rate & mawno or boundname & -- & Simulated mass flow rate for a well or group of wells. \\
-MWT & fw-rate & mawno or boundname & -- & Simulated mass flow rate for a flowing well or group of flowing wells. \\
+MWT & rate & ifno or boundname & -- & Simulated mass flow rate for a well or group of wells. \\
+MWT & fw-rate & ifno or boundname & -- & Simulated mass flow rate for a flowing well or group of flowing wells. \\
 MWT & rate-to-mvr & well or boundname & -- & Simulated mass flow rate that is sent to the MVT Package for a well or group of wells.\\
 MWT & fw-rate-to-mvr & well or boundname & -- & Simulated mass flow rate that is sent to the MVT Package from a flowing well or group of flowing wells. \\
diff --git a/doc/Common/gwt-sftobs.tex b/doc/Common/gwt-sftobs.tex
index 7e1da8f9af0..150b1ee0cdd 100644
--- a/doc/Common/gwt-sftobs.tex
+++ b/doc/Common/gwt-sftobs.tex
@@ -1,16 +1,16 @@
 % general APT observations
-SFT & concentration & rno or boundname & -- & Reach concentration. If boundname is specified, boundname must be unique for each reach. \\
-SFT & flow-ja-face & rno or boundname & rno or -- & Mass flow between two reaches.  If a boundname is specified for ID1, then the result is the total mass flow for all reaches. If a boundname is specified for ID1 then ID2 is not used.\\
-SFT & storage & rno or boundname & -- & Simulated mass storage flow rate for a reach or group of reaches. \\
-SFT & constant & rno or boundname & -- & Simulated mass constant-flow rate for a reach or group of reaches. \\
-SFT & from-mvr & rno or boundname & -- & Simulated mass inflow into a reach or group of reaches from the MVT package. Mass inflow is calculated as the product of provider concentration and the mover flow rate. \\
-SFT & to-mvr & rno or boundname & -- & Mass outflow from a reach, or a group of reaches that is available for the MVR package. If boundname is not specified for ID, then the outflow available for the MVR package from a specific reach is observed. \\
-SFT & sft & rno or boundname & -- & Mass flow rate for a reach or group of reaches and its aquifer connection(s). \\
+SFT & concentration & ifno or boundname & -- & Reach concentration. If boundname is specified, boundname must be unique for each reach. \\
+SFT & flow-ja-face & ifno or boundname & ifno or -- & Mass flow between two reaches.  If a boundname is specified for ID1, then the result is the total mass flow for all reaches. If a boundname is specified for ID1 then ID2 is not used.\\
+SFT & storage & ifno or boundname & -- & Simulated mass storage flow rate for a reach or group of reaches. \\
+SFT & constant & ifno or boundname & -- & Simulated mass constant-flow rate for a reach or group of reaches. \\
+SFT & from-mvr & ifno or boundname & -- & Simulated mass inflow into a reach or group of reaches from the MVT package. Mass inflow is calculated as the product of provider concentration and the mover flow rate. \\
+SFT & to-mvr & ifno or boundname & -- & Mass outflow from a reach, or a group of reaches that is available for the MVR package. If boundname is not specified for ID, then the outflow available for the MVR package from a specific reach is observed. \\
+SFT & sft & ifno or boundname & -- & Mass flow rate for a reach or group of reaches and its aquifer connection(s). \\
 
 %observations specific to the stream transport package
 % rainfall evaporation runoff ext-inflow withdrawal outflow
-SFT & rainfall & rno or boundname & -- & Rainfall rate applied to a reach or group of reaches multiplied by the rainfall concentration. \\
-SFT & evaporation & rno or boundname & -- & Simulated evaporation rate from a reach or group of reaches multiplied by the evaporation concentration. \\
-SFT & runoff & rno or boundname & -- & Runoff rate applied to a reach or group of reaches multiplied by the runoff concentration. \\
-SFT & ext-inflow & rno or boundname & -- & Mass inflow into a reach or group of reaches calculated as the external inflow rate multiplied by the inflow concentration. \\
-SFT & ext-outflow & rno or boundname & -- & External outflow from a reach or group of reaches to an external boundary. If boundname is not specified for ID, then the external outflow from a specific reach is observed. In this case, ID is the reach rno.
+SFT & rainfall & ifno or boundname & -- & Rainfall rate applied to a reach or group of reaches multiplied by the rainfall concentration. \\
+SFT & evaporation & ifno or boundname & -- & Simulated evaporation rate from a reach or group of reaches multiplied by the evaporation concentration. \\
+SFT & runoff & ifno or boundname & -- & Runoff rate applied to a reach or group of reaches multiplied by the runoff concentration. \\
+SFT & ext-inflow & ifno or boundname & -- & Mass inflow into a reach or group of reaches calculated as the external inflow rate multiplied by the inflow concentration. \\
+SFT & ext-outflow & ifno or boundname & -- & External outflow from a reach or group of reaches to an external boundary. If boundname is not specified for ID, then the external outflow from a specific reach is observed. In this case, ID is the reach ifno.
diff --git a/doc/Common/gwt-uztobs.tex b/doc/Common/gwt-uztobs.tex
index 917b46b54a3..87b1c679258 100644
--- a/doc/Common/gwt-uztobs.tex
+++ b/doc/Common/gwt-uztobs.tex
@@ -1,14 +1,14 @@
 % general APT observations
-UZT & concentration & uztno or boundname & -- & uzt cell concentration. If boundname is specified, boundname must be unique for each uzt cell. \\
-UZT & flow-ja-face & uztno or boundname & uztno or -- & Mass flow between two uzt cells.  If a boundname is specified for ID1, then the result is the total mass flow for all uzt cells. If a boundname is specified for ID1 then ID2 is not used.\\
-UZT & storage & uztno or boundname & -- & Simulated mass storage flow rate for a uzt cell or group of uzt cells. \\
-UZT & constant & uztno or boundname & -- & Simulated mass constant-flow rate for a uzt cell or a group of uzt cells. \\
-UZT & from-mvr & uztno or boundname & -- & Simulated mass inflow into a uzt cell or group of uzt cells from the MVT package. Mass inflow is calculated as the product of provider concentration and the mover flow rate. \\
-UZT & uzt & uztno or boundname & -- & Mass flow rate for a uzt cell or group of uzt cells and its aquifer connection(s). \\
+UZT & concentration & ifno or boundname & -- & uzt cell concentration. If boundname is specified, boundname must be unique for each uzt cell. \\
+UZT & flow-ja-face & ifno or boundname & ifno or -- & Mass flow between two uzt cells.  If a boundname is specified for ID1, then the result is the total mass flow for all uzt cells. If a boundname is specified for ID1 then ID2 is not used.\\
+UZT & storage & ifno or boundname & -- & Simulated mass storage flow rate for a uzt cell or group of uzt cells. \\
+UZT & constant & ifno or boundname & -- & Simulated mass constant-flow rate for a uzt cell or a group of uzt cells. \\
+UZT & from-mvr & ifno or boundname & -- & Simulated mass inflow into a uzt cell or group of uzt cells from the MVT package. Mass inflow is calculated as the product of provider concentration and the mover flow rate. \\
+UZT & uzt & ifno or boundname & -- & Mass flow rate for a uzt cell or group of uzt cells and its aquifer connection(s). \\
 
 %observations specific to the uzt package
 % infiltration rej-inf uzet rej-inf-to-mvr
-UZT & infiltration & uztno or boundname & -- & Infiltration rate applied to a uzt cell or group of uzt cells multiplied by the infiltration concentration. \\
-UZT & rej-inf & uztno or boundname & -- & Rejected infiltration rate applied to a uzt cell or group of uzt cells multiplied by the infiltration concentration. \\
-UZT & uzet & uztno or boundname & -- & Unsaturated zone evapotranspiration rate applied to a uzt cell or group of uzt cells multiplied by the uzt cell concentration. \\
-UZT & rej-inf-to-mvr & uztno or boundname & -- & Rejected infiltration rate applied to a uzt cell or group of uzt cells multiplied by the infiltration concentration that is sent to the mover package. \\
+UZT & infiltration & ifno or boundname & -- & Infiltration rate applied to a uzt cell or group of uzt cells multiplied by the infiltration concentration. \\
+UZT & rej-inf & ifno or boundname & -- & Rejected infiltration rate applied to a uzt cell or group of uzt cells multiplied by the infiltration concentration. \\
+UZT & uzet & ifno or boundname & -- & Unsaturated zone evapotranspiration rate applied to a uzt cell or group of uzt cells multiplied by the uzt cell concentration. \\
+UZT & rej-inf-to-mvr & ifno or boundname & -- & Rejected infiltration rate applied to a uzt cell or group of uzt cells multiplied by the infiltration concentration that is sent to the mover package. \\
diff --git a/doc/ReleaseNotes/ReleaseNotes.tex b/doc/ReleaseNotes/ReleaseNotes.tex
index 26fbf93e8d8..0ea54536e6c 100644
--- a/doc/ReleaseNotes/ReleaseNotes.tex
+++ b/doc/ReleaseNotes/ReleaseNotes.tex
@@ -176,6 +176,7 @@ \section{Release History}
 6.4.0 & November 30, 2022 & \url{https://doi.org/10.5066/P9FL1JCC} \\
 6.4.1 & December 9, 2022 & \url{https://doi.org/10.5066/P9FL1JCC} \\
 6.4.2 & June 28, 2023 & \url{https://doi.org/10.5066/P9FL1JCC} \\
+6.4.3 & February 7, 2024 & \url{https://doi.org/10.5066/P9FL1JCC} \\
 \hline
 \label{tab:releases}
 \end{tabular*}
@@ -189,7 +190,7 @@ \section{Changes Introduced in this Release}
 This section describes changes introduced into MODFLOW~6 for the current release.  These changes may substantially affect users.
 
 \begin{itemize}
-\input{v6.4.2.tex}
+\input{develop.tex}
 \end{itemize}
 
 % -------------------------------------------------
@@ -199,7 +200,7 @@ \section{Known Issues and Incompatibilities}
 \begin{enumerate}
 
 \item
-The AUXMULTNAME option can be used to scale input values, such as riverbed conductance, using values in an auxiliary column.  When this AUXMULTNAME option is used, the multiplier value in the AUXMULTNAME column should not be represented with a time series unless the value to scale is also represented with a time series.  
+The READARRAY utility is used by some packages to read arrays of numeric values provided by the user.  The READARRAY utility has an IPRN option (as described in the MODFLOW 6 Description of Input and Output), which will cause the array to be written to the model listing file.  Support for the IPRN option has been removed for some packages and will ultimately be removed for all packages.  An alternative for IPRN functionality is presently under development.
 
 \item
 The capability to use Unsaturated Zone Flow (UZF) routing beneath lakes and streams has not been implemented.
@@ -232,32 +233,34 @@ \section{Known Issues and Incompatibilities}
 
 % -------------------------------------------------
 \section{Distribution File}
-The following distribution file is for use on personal computers: \texttt{\modflowversion.zip}.  The distribution file is a compressed zip file. The following directory structure is incorporated in the zip file:
+The following distribution file is for use on personal computers: \texttt{\modflowversion\_[ostag].zip}.  The distribution file is a compressed zip file. The following directory structure is incorporated in the zip file:
 
 % folder structured created by python script
 \input{folder_struct.tex}
 
-It is recommended that no user files are kept in the \modflowversion~directory structure.  If you do plan to put your own files in the \modflowversion~directory structure, do so only by creating additional subdirectories.
+It is recommended that no user files are kept in the release directory.  If you do plan to put your own files in the release directory, do so only by creating additional subdirectories.
 
 % -------------------------------------------------
 \section{Installation and Execution}
-There is no installation of MODFLOW~6 other than the requirement that \texttt{\modflowversion.zip} must be unzipped into a location where it can be accessed.  
+There is no installation of MODFLOW~6 other than the requirement that \texttt{\modflowversion\_[ostag].zip} must be unzipped into a location where it can be accessed.  
 
 To make the executable versions of MODFLOW~6 accessible from any directory, the directory containing the executables should be included in the PATH environment variable.  Also, if a prior release of MODFLOW~6 is installed on your system, the directory containing the executables for the prior release should be removed from the PATH environment variable.
 
-As an alternative, the executable file, named ``\texttt{mf6.exe}'' on Windows, in the \modflowversion{}/bin directory can be copied into a directory already included in the PATH environment variable.
+As an alternative, the executable file, named ``\texttt{mf6.exe}'' on Windows, in the \modflowversion\_[ostag]/bin directory can be copied into a directory already included in the PATH environment variable.
 
 To run MODFLOW~6, simply type \texttt{mf6} in a terminal window.  The current working directory must be set to a location where the model input files are located.  Upon execution, MODFLOW~6 will immediately look for file with the name \texttt{mfsim.nam} in the current working directory, and will terminate with an error if it does not find this file.
 
 % -------------------------------------------------
 \section{Compiling MODFLOW~6}
-MODFLOW~6 has been compiled using Intel Fortran and GNU Fortran on the Windows, macOS, and Linux operating systems.  Because the program uses relatively new Fortran functionality, recent versions of the compilers may be required for successful compilation.  MODFLOW~6 is currently tested with gfortran 7-12 on Linux and gfortran 12 on macOS and Windows.  If you have gfortran installed on your computer, you can tell which version it is by entering ``\verb|gfortran --version|'' at a terminal window.  MODFLOW~6 is currently not compatible with the next-generation Intel Fortran Compiler; a recent version of the Intel Fortran Compiler Classic (e.g. 2021.8.0) must be used.
+MODFLOW~6 has been compiled using Intel Fortran and GNU Fortran on Windows, macOS, and several Linux operating systems. All MODFLOW~6 distributions are currently compiled with Intel Fortran. Because the program uses relatively new Fortran functionality, recent versions of the compilers may be required for successful compilation. MODFLOW~6 is not yet compatible with the latest versions of the Intel toolchain, however.
+
+MODFLOW~6 is currently tested with gfortran 7-12 on Linux and gfortran 12 on macOS and Windows. The gfortran version can be queried with ``\verb|gfortran --version|''.  Intel Fortran Compiler Classic version 2022.3.0 is currently tested on all three platforms. Some 2021 versions have also been reported compatible. At this time, MODFLOW~6 is not compatible with the next-generation Intel Fortran Compiler `ifx`.
 
 Meson is the recommended build tool for MODFLOW~6.  For more detailed compilation instructions, please refer to \url{https://github.com/MODFLOW-USGS/modflow6/blob/develop/DEVELOPER.md#building}.
 
 This distribution contains the Microsoft Visual Studio solution and project files for compiling MODFLOW~6 on Windows using the Intel Fortran Compiler Classic.  The files have been used successfully with recent versions of Microsoft Visual Studio Community 2019 and the Intel Fortran Compiler Classic.
 
-This distribution also comes with a makefile for compiling MODFLOW~6 with \texttt{gfortran}.  The makefile is contained in the \texttt{make} folder.
+This distribution also includes a makefile for compiling MODFLOW~6 with \texttt{gfortran}.  The makefile is contained in the \texttt{make} folder.
 
 For those familiar with Python, the pymake package can also be used to compile MODFLOW~6.  Additional information on the Python pymake utility can be found at: \url{https://github.com/modflowpy/pymake}.
 
@@ -295,6 +298,10 @@ \section{MODFLOW~6 Documentation}
  
 \noindent Description of the MODFLOW~6 input and output is included in this distribution in the ``doc'' folder as mf6io.pdf.
 
+% -------------------------------------------------
+% if deprecation information exists, then include the deprecation table
+\IfFileExists{./deprecations.tex}{\input{./deprecations.tex}}{}
+
 % -------------------------------------------------
 % if runtime information exists, then include the run time comparison table
 \IfFileExists{./run-time-comparison.tex}{\input{./run-time-comparison.tex}}{}
diff --git a/doc/ReleaseNotes/appendixA.tex b/doc/ReleaseNotes/appendixA.tex
index 2bad0245dce..199d7151043 100644
--- a/doc/ReleaseNotes/appendixA.tex
+++ b/doc/ReleaseNotes/appendixA.tex
@@ -1,5 +1,6 @@
 This appendix describes changes introduced into MODFLOW~6 in previous releases. These changes may substantially affect users.
 
+        \input{./previous/v6.4.2.tex}
         \input{./previous/v6.4.1.tex}
         \input{./previous/v6.4.0.tex}        
         \input{./previous/v6.3.0.tex}	
diff --git a/doc/ReleaseNotes/develop.tex b/doc/ReleaseNotes/develop.tex
new file mode 100644
index 00000000000..05253619fd4
--- /dev/null
+++ b/doc/ReleaseNotes/develop.tex
@@ -0,0 +1,64 @@
+% Use this template for starting initializing the release notes
+% after a release has just been made.
+	
+	\item \currentmodflowversion
+
+	\underline{NEW FUNCTIONALITY}
+	\begin{itemize}
+		\item The Input Data Processor (IDP), first released in version 6.4.2, is a general utility for reading user-provided input files.  Package-specific routines for reading input files continue to be replaced by the IDP approach.  For packages that use IDP for input, logging information is written to the simulation list file (mfsim.lst).  Additional information on the IDP and the list of supported packages is contained in the MODFLOW 6 Description of Input and Output (mf6io.pdf) under a section titled ``Processing of Program Input.''
+		\item The source code was refactored to support compilation of a parallel version of MODFLOW 6 based on the Message Passing Interface (MPI) and the Portable, Extensible Toolkit for Scientific Computation (PETSc) libraries.  The parallel version of MODFLOW is considered preliminary. Limited testing of the parallel version has been performed on laptops, desktops, and supercomputers, but significant changes are expected in future releases. User support for the parallel version of MODFLOW 6 may be provided in the future.
+	%	\item xxx
+	\end{itemize}
+
+	\underline{EXAMPLES}
+	\begin{itemize}
+		\item A new exampled called ex-gwf-rad-disu was added.  This new example uses a DISU grid to represent radial groundwater flow to a pumping well.
+		\item A new exampled called ex-gwf-curv-90 was added.  This new example demonstrates use of a DISV grid to represent a curvilinear spatial discretization.  For this example, the curvilinear grid is applied to one quarter of a radial groundwater flow system.
+		\item A new exampled called ex-gwf-curvilin was added.  This new example uses a curvilinear grid, represented with the DISV Package, to simulate groundwater flow through a multi-region aquifer with bends in the domain boundaries.
+	\end{itemize}
+
+	\textbf{\underline{BUG FIXES AND OTHER CHANGES TO EXISTING FUNCTIONALITY}} \\
+	\underline{BASIC FUNCTIONALITY}
+	\begin{itemize}
+		\item Improve error message if the size of data read from a binary array file is inconsistent with READARRAY control line and variable description keywords.
+		\item The area calculation for cells in the DISV package was inaccurate for some cases with very large cell vertex coordinates.  The area calculation was improved by using transformed cell vertex coordinates prior to making the area calculation.
+		\item Auxiliary variables in RCH and EVT Array-Based input packages are now reset to zero when otherwise not specified in period input data and the auxiliary parameter is not controlled by a time-series.
+	%	\item xxx
+	%	\item xxx
+	\end{itemize}
+
+	\underline{INTERNAL FLOW PACKAGES}
+	\begin{itemize}
+		\item The data header in the binary output file written by the viscosity (VSC) package was printing `` VISCOSI'' instead of `` VISCOSITY''. The viscosity package now prints the full `` VISCOSITY'' header in the binary output file.
+		\item The CSUB Package did not support output of z-displacement arrays for models using the DISU package.  The CSUB package was updated to support calculation of z-displacement arrays for DISU model grids.
+	%	\item xxx
+	\end{itemize}
+
+	\underline{STRESS PACKAGES}
+	\begin{itemize}
+		\item This release contains a fix for a longstanding issue related to the use of AUXMULTNAME and time series.  Previous release notes included the following description of a known issue: \textit{``The AUXMULTNAME option can be used to scale input values, such as riverbed conductance, using values in an auxiliary column.  When this AUXMULTNAME option is used, the multiplier value in the AUXMULTNAME column should not be represented with a time series unless the value to scale is also represented with a time series.''}  With this release, the Input Data Processor (IDP) is now used to read stress package input files, and the limitation with AUXMULTNAME and time series no longer applies.
+	%	\item xxx
+	%	\item xxx
+	\end{itemize}
+
+	\underline{ADVANCED STRESS PACKAGES}
+	\begin{itemize}
+		\item Added functionality to support zero values for each grid dimension when specifying the CELLID for SFR reaches that are not connected to an underlying groundwater grid cell. For example, for a DIS grid a CELLID of 0 0 0 should be specified for reaches with no connection to a groundwater cell. Warning messages will be issued if NONE is specified for the CELLID of an unconnected reach. Specifying a CELLID of NONE will eventually be deprecated and will cause MODFLOW 6 to terminate with an error.
+		\item Added functionality to support specification of a DNODATA (3.0E+30) BEDLEAK value for LAK package connections.  This DNODATA value is used to identify lake-GWF connections where conductance is solely a function of aquifer properties in the connected GWF cell.  In this case, the lakebed sediments are assumed to be absent and all resistance to flow is assumed to be within the GWF cell. Warning messages are now issued if NONE is specified for LAK package connections. Specifying a BEDLEAK value equal to NONE will eventually be deprecated and will cause MODFLOW 6 to terminate with an error.
+		\item SFR diversion would not be updated if the outflow of its upstream reach is zero. If diversion was not zero in the previous stress period, it would report mass balance error in the SFR budget. This bug was fixed by always updating the diversion.
+	%	\item xxx
+	\end{itemize}
+
+	%\underline{SOLUTION}
+	%\begin{itemize}
+	%	\item xxx
+	%	\item xxx
+	%	\item xxx
+	%\end{itemize}
+
+	\underline{EXCHANGES}
+	\begin{itemize}
+		\item A model budget error would occur when a constant-head (CHD) cell in one model had a direct connection to an active cell in another model.  For the model budget to be calculated correctly a new term called ``FLOW-JA-FACE-CHD'' was added to the GWF model budget.  This term is only included in the budget table when the GWF Model is connected to another GWF Model using a GWF-GWF Exchange.  Additionally, the CHD budget calculation for a very specific (and rare) configuration was also incorrect. The incorrect budget calculation occurred when the following conditions were met: (1) a GWF model was connected to another GWF model with a GWF-GWF Exchange; (2) the model as well as the Exchange had the XT3D option enabled, and (3) the model was configured with a CHD cell that is either an Exchange cell, i.e. a cell that is part of the EXCHANGEDATA block, or a cell directly connected to such an Exchange cell.  The size of the error depends on the degree of anisotropy around the particular CHD cell and shows up as a discrepancy in the volume budget table reported in the GWF list file. The program has been updated with the correct budget calculation.
+	%	\item xxx
+	%	\item xxx
+	\end{itemize}
diff --git a/doc/ReleaseNotes/folder_struct.tex b/doc/ReleaseNotes/folder_struct.tex
index 51ba1dc21b0..544ea59f8e8 100644
--- a/doc/ReleaseNotes/folder_struct.tex
+++ b/doc/ReleaseNotes/folder_struct.tex
@@ -1,5 +1,5 @@
 \begin{verbatim}
-mf6.x.x/ 
+\modflowversion
     bin/ 
     doc/ 
     examples/ 
diff --git a/doc/ReleaseNotes/mk_deprecations.py b/doc/ReleaseNotes/mk_deprecations.py
new file mode 100644
index 00000000000..128481c2893
--- /dev/null
+++ b/doc/ReleaseNotes/mk_deprecations.py
@@ -0,0 +1,72 @@
+# This script converts the markdown deprecations table
+# into a latex table for inclusion in the release notes
+import argparse
+from pathlib import Path
+from warnings import warn
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument("path")
+    args = parser.parse_args()
+
+    header = r"""
+    \section{Deprecations}
+
+    Deprecated/removed options in the current version of MODFLOW 6. Deprecated options are not suggested for use and may (but need not) be removed in a future version of MODFLOW 6. Removed options are no longer available in the current version of MODFLOW 6.
+
+    \small
+    \begin{longtable}[!htbp]{p{5cm} p{3cm} p{3cm} p{1.5cm}}
+    \caption{List of deprecations and removals}
+    \label{table:deprecations}
+    \tabularnewline
+
+    \hline
+    \hline
+    \textbf{Model--Package} & \textbf{Option} & \textbf{Deprecated} & \textbf{Removed}   \\
+    \hline
+    \endfirsthead
+
+    \hline
+    \hline
+    \textbf{Model--Package} & \textbf{Option} & \textbf{Deprecated} & \textbf{Removed}   \\
+    \hline
+    \endhead
+
+    """
+
+    footer = r"""
+    \hline
+    \end{longtable}
+    \normalsize
+    """
+
+    fname = "deprecations"
+    fpath = Path(args.path).expanduser().absolute()
+    fnametex = Path(f"{fname}.tex").absolute()
+    fnametex.unlink(missing_ok=True)
+
+    # if the markdown file exists, convert it to latex
+    if fpath.is_file():
+        ftex = open(fnametex, 'w')
+        ftex.write(header)
+        skipline = True
+        with open(fpath) as fmd:
+            for line in fmd:
+                if not skipline:
+                    ll = line.strip().split('|')
+                    ll = ll[1:-1]
+                    linetex = "& ".join(ll)
+                    linetex = linetex.replace("\\", "/")
+                    linetex += '\\\\' + '\n'
+                    linetex = linetex.replace("%", "\\%")
+                    linetex = linetex.replace("_", "\\_")
+                    ftex.write(linetex)
+                    ftex.write("\\hline\n")
+                if ":-" in line:
+                    skipline = False
+        ftex.write(footer)
+        ftex.close()
+        print(f"Created LaTex file {fnametex} from markdown deprecations file {fpath}")
+    else:
+        warn(f"Deprecations not found: {fpath}")
diff --git a/doc/ReleaseNotes/v6.4.2.tex b/doc/ReleaseNotes/previous/v6.4.2.tex
similarity index 99%
rename from doc/ReleaseNotes/v6.4.2.tex
rename to doc/ReleaseNotes/previous/v6.4.2.tex
index 8d718485fc1..afc3511061a 100644
--- a/doc/ReleaseNotes/v6.4.2.tex
+++ b/doc/ReleaseNotes/previous/v6.4.2.tex
@@ -2,7 +2,7 @@
 % after a release has just been made.
 	
 	%\item \currentmodflowversion
-	\item Version mf6.4.2--June 28, 2023
+	\subsection{Version mf6.4.2--June 28, 2023}
 	
 	\underline{NEW FUNCTIONALITY}
 	\begin{itemize}
diff --git a/doc/mf6io/body.tex b/doc/mf6io/body.tex
index b34c0b6f72b..32f0150cf94 100644
--- a/doc/mf6io/body.tex
+++ b/doc/mf6io/body.tex
@@ -11,11 +11,15 @@
 
 %General form of input instructions
 \SECTION{Form of Input Instructions}
-\input{form_of_input.tex}
+\input{framework/form_of_input.tex}
+\input{framework/array_data.tex}
+\input{framework/binary_array_input}
+\input{framework/list_data.tex}
+\input{framework/binary_list_input}
 
 %Processing of program input
 \SECTION{Processing of Program Input}
-\input{processing_of_input.tex}
+\input{framework/processing_of_input.tex}
 
 %Simulation name file
 \newpage
@@ -59,7 +63,7 @@
 %Binary files
 \newpage
 \SECTION{Description of Binary Output Files for the Groundwater Flow (GWF) and Groundwater Transport (GWT) Models }
-\input{gwf/binaryoutput}
+\input{framework/binaryoutput}
 
 \newpage
 \ifx\usgsdirector\undefined
diff --git a/doc/mf6io/gwf/array_data.tex b/doc/mf6io/framework/array_data.tex
similarity index 53%
rename from doc/mf6io/gwf/array_data.tex
rename to doc/mf6io/framework/array_data.tex
index 4a2c400bc79..ac36dec8c92 100644
--- a/doc/mf6io/gwf/array_data.tex
+++ b/doc/mf6io/framework/array_data.tex
@@ -1,5 +1,5 @@
 \subsection{Array Input (READARRAY)}
-Some GWF Model packages require arrays of information to be provided by the user.  This information is read using a generic READARRAY capability in \mf.  Within this user guide, variables that are read with READARRAY are marked accordingly, as shown in example input instructions for a DATA block.  
+Some \mf Model packages require arrays of information to be provided by the user.  This information is read using a generic READARRAY capability in \mf.  Within this user guide, variables that are read with READARRAY are marked accordingly, as shown in example input instructions for a DATA block.  
 
 \begin{lstlisting}[style=blockdefinition]
 BEGIN DATA
@@ -96,7 +96,7 @@ \subsubsection{READARRAY Examples}
 \end{lstlisting}
 
 
-Some arrays define information that is required for the entire model grid, or part of a model grid.  This type of information is provided in a special type of data block called a ``GRIDDATA'' block.  For example, hydraulic conductivity is required for every cell in the model grid.  Hydraulic conductivity is read from a ``GRIDDATA'' block in the NPF Package input file.  For GRIDDATA arrays with one value for every cell in the model grid, the arrays can optionally be read in a LAYERED format, in which an array is provided for each layer of the grid.  Alternatively, the array can be read for the entire model grid.  As an example, consider the GRIDDATA block for the IC Package shown below:
+Some arrays define information that is required for the entire model grid, or part of a model grid.  This type of information is provided in a special type of data block called a ``GRIDDATA'' block.  For example, hydraulic conductivity is required for every cell in the model grid.  Hydraulic conductivity is read from a ``GRIDDATA'' block in the \mf GWF NPF Package input file.  For GRIDDATA arrays with one value for every cell in the model grid, the arrays can optionally be read in a LAYERED format, in which an array is provided for each layer of the grid.  Alternatively, the array can be read for the entire model grid.  As an example, consider the GRIDDATA block for the \mf GWF or GWT IC Package shown below:
 
 \lstinputlisting[style=blockdefinition]{./mf6ivar/tex/gwf-ic-griddata.dat}
 
@@ -104,7 +104,7 @@ \subsubsection{READARRAY Examples}
 
 For a structured DIS model, the READARRAY utility is used to read arrays that are dimensioned to the full size of the grid (of size \texttt{nlay*nrow*ncol}). This utility first reads an array name, which associates the input to be read with the desired array.  For these arrays, an optional keyword ``LAYERED'' can be located next to the array name.  If ``LAYERED'' is detected, then a control line is provided for each layer and the array is filled with values for each model layer.  If the ``LAYERED'' keyword is absent, then a single control line is used and the entire array is filled at once.
 
-For example, the following block shows one way the starting head array (STRT) could be specified for a model with 4 layers.  Following the array name and the ``LAYERED'' keyword are four control lines, one for each layer.
+For example, the following block shows one way the \mf GWF model starting head array (STRT) could be specified for a model with 4 layers.  Following the array name and the ``LAYERED'' keyword are four control lines, one for each layer.
 
 \begin{lstlisting}[style=inputfile]
   STRT LAYERED
@@ -121,41 +121,21 @@ \subsubsection{READARRAY Examples}
      CONSTANT 10.0  #applies to all cells in the grid
 \end{lstlisting}
 
-\subsection{List Input}
-Some items consist of several variables, such as layer, row, column, stage, and conductance, for example.  List input refers to a block of data with a separate item on each line.  For some common list types, the first set of variables is a cell identifier (denoted as \texttt{cellid} in this guide), such as layer, row, and column. With lists, the input data for each item must start on a new line. All variables for an item are assumed to be contained in a single line.  Each input variable has a data type, which can be Double Precision, Integer, or Character. Integers are whole numbers and must not include a decimal point or exponent. Double Precision numbers can include a decimal point and an exponent. If no decimal point is included in the entered value, then the decimal point is assumed to be at the right side of the value. Any printable character is allowed for character variables. 
-
-Variables starting with the letters I-N are most commonly integers; however, in some instances, a character string may start with the letters I-N. Variables starting with the letters A-H and O-Z are primarily double precision numbers; however, these variable names may also be used for character data.  In \mf all variables are explicitly declared within the source code, as opposed to the implicit type declaration in previous MODFLOW versions.  This explicit declaration means that the variable type can be easily determined from the source code.
-
-Free formatting is used throughout the input instructions.  With free format, values are not required to occupy a fixed number of columns in a line. Each value can occupy one or more columns as required to represent the value; however, the values must still be included in the prescribed order. One or more spaces, or a single comma optionally combined with spaces, must separate adjacent values. Also, a numeric value of zero must be explicitly represented with 0 and not by one or more spaces when free format is used, because detecting the difference between a space that represents 0 and a space that represents a value separator is not possible. Free format is similar to Fortran's list directed input.
-
-Two capabilities included in Fortran's list-directed input are not included in the free-format input implemented in \mf. Null values in which input values are left unchanged from their previous values are not allowed. In general, MODFLOW's input values are not defined prior to their input.  A ``/'' cannot be used to terminate an input line without including values for all the variables; data values for all required input variables must be explicitly specified on an input line.  For character data, MODFLOW's free format implementation is less stringent than the list-directed input of Fortran. Fortran requires character data to be delineated by apostrophes. MODFLOW does not require apostrophes unless a blank or a comma is part of a character variable.
-
-As an example of a list, consider the PERIOD block for the GHB Package.  The input format is  shown below:
-
-\lstinputlisting[style=blockdefinition]{./mf6ivar/tex/gwf-ghb-period.dat}
-
-Each line represents a separate item, which consists of variables.  In this case, the first variable of the item, \texttt{cellid} is an array of size \texttt{ncelldim}.  The next two variables of the item are \texttt{bhead} and \texttt{cond}.  Lastly, the item has two optional variables, \texttt{aux} and \texttt{boundname}.  Three of the variables shown in the list are colored in blue.  Variables that are colored in blue mean that they can be represented with a time series.  The time series capability is described in the section on Time-Variable Input in this document.  
-
-The following is simple example of a PERIOD block for the GHB Package, which shows how a list is entered by the user.
+In the next example, the ``LAYERED'' keyword is present and binary files are used for each layer. A control line with the ``BINARY'' keyword is required for each layer.
 
 \begin{lstlisting}[style=inputfile]
-BEGIN PERIOD 1
-#      lay       row       col     stage      cond
-         1        13         1     988.0     0.038
-         1        14         9    1045.0     0.038
-END PERIOD
-\end{lstlisting}
-
-As described earlier in the section on ``Block and Keyword Input,'' block information can be read from a separate text file.  To activate reading a list from separate text file, the first and only entry in the block must be a control line of the following form:  
-
-\begin{lstlisting}[style=blockdefinition]
-  OPEN/CLOSE <fname>
+  STRT LAYERED
+     OPEN/CLOSE strt.layer1.bin (BINARY)  #layer1
+     OPEN/CLOSE strt.layer2.bin (BINARY)  #layer2
+     OPEN/CLOSE strt.layer3.bin (BINARY)  #layer3
+     OPEN/CLOSE strt.layer4.bin (BINARY)  #layer4
 \end{lstlisting}
 
-\noindent where \texttt{fname} is the name of the file containing the list.  Lists for the stress packages (CHD, WEL, DRN, RIV, GHB, RCH, and EVT) have an additional BINARY option.  The BINARY  option is not supported for the advanced stress packages (LAK, MAW, SFR, UZF).  The BINARY options is specified as follows:
+In the next example, the ``LAYERED'' keyword is absent. In this case, a single control line with the ``BINARY'' keyword is required and the binary file will include the entire data array.
 
-\begin{lstlisting}[style=blockdefinition]
-  OPEN/CLOSE <fname> [(BINARY)]
+\begin{lstlisting}[style=inputfile]
+  STRT
+     OPEN/CLOSE strt.bin (BINARY)  #layers1-4
 \end{lstlisting}
 
-If the (BINARY) keyword is found on the control line, then the file is opened as an unformatted file on unit 99, and the list is read.  There are a number of requirements for using the (BINARY) option for lists.  All stress package lists begin with integer values for the \texttt{cellid} (layer, row, and column, for example).  These values must be represented as integer numbers in the unformatted file.  Also, all auxiliary data must be included in the binary file; auxiliary data must be represented as double precision numbers.  Lastly, the (BINARY) option does not support entry of \texttt{boundname}, and so the BOUNDNAMES option should not be activated in the OPTIONS block for the package.  
\ No newline at end of file
+A consequence of the way binary input files have been implemented in \mf, simulated dependent variable binary output (for example, head and concentration) cannot be used as binary array input for a model. Instead, simulated dependent variable binary output must be processed and split into separate binary files for each layer or combined into a single array equal to the size of the grid (for DIS grids this would be an array equal to NCOL * NROW * NLAY).
diff --git a/doc/mf6io/framework/binary_array_input.tex b/doc/mf6io/framework/binary_array_input.tex
new file mode 100644
index 00000000000..73bfbd38f1d
--- /dev/null
+++ b/doc/mf6io/framework/binary_array_input.tex
@@ -0,0 +1,88 @@
+\subsubsection{Description of Binary Array Input Files}
+All floating point variables are written to the binary input files as DOUBLE PRECISION Fortran variables. Integer variables are written to the input files as Fortran integer variables. Some variables are character strings and are indicated as so in the following descriptions. Binary array data are written using the following two records:
+
+\vspace{5mm}
+\noindent Record 1: \texttt{KSTP,KPER,PERTIM,TOTIM,TEXT,M1,M2,M3} \\
+\noindent Record 2: \texttt{DATA} \\
+
+\vspace{5mm}
+\noindent where
+
+\begin{description} \itemsep0pt \parskip0pt \parsep0pt
+\item \texttt{KSTP} is the time step number;
+\item \texttt{KPER} is the stress period number;
+\item \texttt{PERTIM} is the time value for the current stress period; 
+\item \texttt{TOTIM} is the total simulation time;
+\item \texttt{TEXT} is a character string (character*16);
+\item \texttt{M1} is the length of the data in the fastest varying direction;
+\item \texttt{M2} is the length of the data in the second fastest varying direction;
+\item \texttt{M3} can be any value but is typically 1 or the layer number for the data; and
+\item \texttt{DATA} is the array data of size (M1*M2).
+\end{description}
+ 
+\noindent The values specified for \texttt{M1}, \texttt{M2}, and \texttt{M3} in Record 1 are dependent on the grid type and if the ``LAYERED'' keyword is present on the READARRAY control line.  For binary array data, \texttt{KSTP}, \texttt{KPER}, \texttt{PERTIM}, \texttt{TOTIM}, and \texttt{TEXT} can be set to any value. Binary array input file specifications for each discretization type are given below.
+
+\paragraph{DIS Grids}
+For DIS grids,  \texttt{M1=NCOL}, \texttt{M2=NROW}, and \texttt{M3=ILAY} when the ``LAYERED'' keyword is present on the READARRAY control line. For this case, record 1 and 2 should be written as:
+
+\vspace{5mm}
+\noindent Record 1: \texttt{KSTP,KPER,PERTIM,TOTIM,TEXT,M1,M2,M3} \\
+\noindent Record 2: \texttt{((DATA(J,I,ILAY),J=1,NCOL),I=1,NROW)} \\
+
+\vspace{5mm}
+\noindent where
+
+\begin{description} \itemsep0pt \parskip0pt \parsep0pt
+\item \texttt{NCOL} is the number of columns;
+\item \texttt{NROW} is the number of rows; and
+\item \texttt{ILAY} is the layer number.
+\end{description}
+
+\noindent For DIS grids, \texttt{M1=NCOL*NROW*NLAY}, \texttt{M2=1}, and \texttt{M3=1} when the ``LAYERED'' keyword is absent on the READARRAY control line. For this case, record 1 and 2 should be written as:
+
+\vspace{5mm}
+\noindent Record 1: \texttt{KSTP,KPER,PERTIM,TOTIM,TEXT,M1,M2,M3} \\
+\noindent Record 2: \texttt{(((DATA(J,I,K),J=1,NCOL),I=1,NROW),K=1,NLAY)} \\
+
+\vspace{5mm}
+\noindent where
+
+\begin{description} \itemsep0pt \parskip0pt \parsep0pt
+\item \texttt{NLAY} is the number of layers.
+\end{description}
+
+\paragraph{DISV Grids}
+For DISV grids, \texttt{M1=NCPL}, \texttt{M2=1}, and \texttt{M3=ILAY} when the ``LAYERED'' keyword is present on the READARRAY control line. For this case, record 1 and 2 should be written as:
+
+\vspace{5mm}
+\noindent Record 1: \texttt{KSTP,KPER,PERTIM,TOTIM,TEXT,M1,M2,M3} \\
+\noindent Record 2: \texttt{(DATA(J,ILAY),J=1,NCPL)} \\
+
+\vspace{5mm}
+\noindent where
+
+\begin{description} \itemsep0pt \parskip0pt \parsep0pt
+\item \texttt{NCPL} is the number of cells per layer.
+\end{description}
+
+\noindent For DISV grids, \texttt{M1=NCPL*NLAY}, \texttt{M2=1}, and \texttt{M3=1} when the ``LAYERED'' keyword is absent on the READARRAY control line. For this case, record 1 and 2 should be written as:
+
+\vspace{5mm}
+\noindent Record 1: \texttt{KSTP,KPER,PERTIM,TOTIM,TEXT,M1,M2,M3} \\
+\noindent Record 2: \texttt{((DATA(J,K),J=1,NCPL),K=1,NLAY)} \\
+
+
+\paragraph{DISU Grids}
+For DISU grids, \texttt{M1=NODES}, \texttt{M2=1}, \texttt{M3=1}. For this case, record 1 and 2 should be written as:
+
+
+\vspace{5mm}
+\noindent Record 1: \texttt{KSTP,KPER,PERTIM,TOTIM,TEXT,M1,M2,M3} \\
+\noindent Record 2: \texttt{(DATA(N),N=1,NODES)} \\
+
+\vspace{5mm}
+\noindent where
+
+\begin{description} \itemsep0pt \parskip0pt \parsep0pt
+\item \texttt{NODES} is the number cells in the model grid.
+\end{description}
diff --git a/doc/mf6io/framework/binary_list_input.tex b/doc/mf6io/framework/binary_list_input.tex
new file mode 100644
index 00000000000..10ee136062a
--- /dev/null
+++ b/doc/mf6io/framework/binary_list_input.tex
@@ -0,0 +1,18 @@
+\subsubsection{Description of Binary List Input Files}
+All floating point variables are written to the binary input files as DOUBLE PRECISION Fortran variables. Integer variables are written to the input files as Fortran integer variables. Auxiliary variables can be included in binary list input files but as indicated previously binary list input files can not be used for packages that include BOUNDNAMES keyword in the OPTIONS block. The format of binary list data are described below.
+
+\vspace{5mm}
+\noindent Record 1: \texttt{(CELLID(N),(RLIST(I,N),I=1,NDAT)(AUXVAR(I,N),I=1, NAUX), N=1,NLIST)}\\
+
+\noindent where
+
+\begin{description} \itemsep0pt \parskip0pt \parsep0pt
+\item \texttt{CELLID} is the cell identifier, and depends on the type of grid that is used for the simulation.;
+\item \texttt{RLIST} is a double precision two-dimensional array of size (NDAT,NLIST) containing the stress package PERIOD data;
+\item \texttt{NDAT} is the number of columns in RLIST, which is the number of columns of real data in the stress package PERIOD data;
+\item \texttt{AUXVAR} is a double precision two-dimensional array of size (NAUX,NLIST)  containing the auxilary data for the stress package PERIOD data;
+\item \texttt{NAUX} is the number of columns in AUXVAR, which is the number of columns of real auxiliary data the in stress package PERIOD data;
+\item \texttt{NLIST} is the size of the list;
+\end{description}
+
+\noindent For a structured grid that uses the DIS input file, CELLID is the layer, row, and column. For a grid that uses the DISV input file, CELLID is the layer and CELL2D number. If the model uses the unstructured discretization (DISU) input file, CELLID is the node number for the cell. \texttt{NLIST} must be less than or equal to \texttt{MAXBOUND} for a stress package. \texttt{NAUX} is determined by the number of \texttt{AUXILIARY} variable names define in the OPTIONS block for the stress package.
diff --git a/doc/mf6io/gwf/binaryoutput.tex b/doc/mf6io/framework/binaryoutput.tex
similarity index 99%
rename from doc/mf6io/gwf/binaryoutput.tex
rename to doc/mf6io/framework/binaryoutput.tex
index 985356b87e1..a217180286d 100644
--- a/doc/mf6io/gwf/binaryoutput.tex
+++ b/doc/mf6io/framework/binaryoutput.tex
@@ -540,7 +540,7 @@ \subsubsection{GWF Model LAK, MAW, SFR, and UZF Packages}
 \texttt{FW-RATE} & 6 & 1 / \texttt{nmawwells} & calculated flowing well discharge rate from the multi-aquifer well. Only saved if \texttt{FLOWING\_WELLS} is specified in the OPTIONS block. The multi-aquifer well number is written to (\texttt{ID1}) and (\texttt{ID2}). \\
 \texttt{STORAGE} & 6 & 2 / \texttt{nmawwells} & Calculated flow from storage for multi-aquifer well. Only saved if the \texttt{NO\_WELL\_STORAGE} is not specified in the OPTIONS block. The multi-aquifer well number is written to (\texttt{ID1}) and (\texttt{ID2}). The multi-aquifer well volume (\texttt{VOLUME}) is saved as an auxiliary data item for this flow term. \\
 \texttt{CONSTANT} & 6 & 1 / \texttt{nmawwells} & Calculated flow to maintain constant head in multi-aquifer well. The multi-aquifer well number is written to (\texttt{ID1}) and (\texttt{ID2}). \\
-\texttt{FROM-MVR} & 6 & 1 / \texttt{nmawwells} & Calculated flow to lake from the MVR Package. Only saved if MVR Package is used in the MAW Package. The lake number is written to (\texttt{ID1}) and (\texttt{ID2}). \\
+\texttt{FROM-MVR} & 6 & 1 / \texttt{nmawwells} & Calculated flow to multi-aquifer well from the MVR Package. Only saved if MVR Package is used in the MAW Package. The multi-aquifer well number is written to (\texttt{ID1}) and (\texttt{ID2}). \\
 \texttt{RATE-TO-MVR} & 6 & 1 / \texttt{nmawwells} & Calculated pumping rate from the multi-aquifer well to the MVR Package. Only saved if MVR Package is used in the MAW Package. The multi-aquifer well number is written to (\texttt{ID1}) and (\texttt{ID2}). \\
 \texttt{FW-RATE-TO-MVR} & 6 & 1 / \texttt{nmawwells} & Calculated flowing well flow from a multi-aquifer well to the MVR Package. Only saved if MVR Package is used in the MAW Package and the \texttt{FLOWING\_WELLS} is specified in the OPTIONS block. The multi-aquifer well number is written to (\texttt{ID1}) and (\texttt{ID2}). \\
 \texttt{AUXILIARY} & 6 & \texttt{naux}+1 / \texttt{nmawwells} & Auxiliary variables, if specified in the MAW Package, are saved to this flow term. The first entry of the \texttt{DATA2D} column has a value of zero. The multi-aquifer well number is written to (\texttt{ID1}) and (\texttt{ID2}).
diff --git a/doc/mf6io/form_of_input.tex b/doc/mf6io/framework/form_of_input.tex
similarity index 100%
rename from doc/mf6io/form_of_input.tex
rename to doc/mf6io/framework/form_of_input.tex
diff --git a/doc/mf6io/framework/list_data.tex b/doc/mf6io/framework/list_data.tex
new file mode 100644
index 00000000000..59669b62316
--- /dev/null
+++ b/doc/mf6io/framework/list_data.tex
@@ -0,0 +1,38 @@
+\subsection{List Input}
+Some items consist of several variables, such as layer, row, column, stage, and conductance, for example.  List input refers to a block of data with a separate item on each line.  For some common list types, the first set of variables is a cell identifier (denoted as \texttt{cellid} in this guide), such as layer, row, and column. With lists, the input data for each item must start on a new line. All variables for an item are assumed to be contained in a single line.  Each input variable has a data type, which can be Double Precision, Integer, or Character. Integers are whole numbers and must not include a decimal point or exponent. Double Precision numbers can include a decimal point and an exponent. If no decimal point is included in the entered value, then the decimal point is assumed to be at the right side of the value. Any printable character is allowed for character variables. 
+
+Variables starting with the letters I-N are most commonly integers; however, in some instances, a character string may start with the letters I-N. Variables starting with the letters A-H and O-Z are primarily double precision numbers; however, these variable names may also be used for character data.  In \mf all variables are explicitly declared within the source code, as opposed to the implicit type declaration in previous MODFLOW versions.  This explicit declaration means that the variable type can be easily determined from the source code.
+
+Free formatting is used throughout the input instructions.  With free format, values are not required to occupy a fixed number of columns in a line. Each value can occupy one or more columns as required to represent the value; however, the values must still be included in the prescribed order. One or more spaces, or a single comma optionally combined with spaces, must separate adjacent values. Also, a numeric value of zero must be explicitly represented with 0 and not by one or more spaces when free format is used, because detecting the difference between a space that represents 0 and a space that represents a value separator is not possible. Free format is similar to Fortran's list directed input.
+
+Two capabilities included in Fortran's list-directed input are not included in the free-format input implemented in \mf. Null values in which input values are left unchanged from their previous values are not allowed. In general, MODFLOW's input values are not defined prior to their input.  A ``/'' cannot be used to terminate an input line without including values for all the variables; data values for all required input variables must be explicitly specified on an input line.  For character data, MODFLOW's free format implementation is less stringent than the list-directed input of Fortran. Fortran requires character data to be delineated by apostrophes. MODFLOW does not require apostrophes unless a blank or a comma is part of a character variable.
+
+As an example of a list, consider the PERIOD block for the GHB Package.  The input format is  shown below:
+
+\lstinputlisting[style=blockdefinition]{./mf6ivar/tex/gwf-ghb-period.dat}
+
+Each line represents a separate item, which consists of variables.  In this case, the first variable of the item, \texttt{cellid} is an array of size \texttt{ncelldim}.  The next two variables of the item are \texttt{bhead} and \texttt{cond}.  Lastly, the item has two optional variables, \texttt{aux} and \texttt{boundname}.  Three of the variables shown in the list are colored in blue.  Variables that are colored in blue mean that they can be represented with a time series.  The time series capability is described in the section on Time-Variable Input in this document.  
+
+The following is simple example of a PERIOD block for the GHB Package, which shows how a list is entered by the user.
+
+\begin{lstlisting}[style=inputfile]
+BEGIN PERIOD 1
+#      lay       row       col     stage      cond
+         1        13         1     988.0     0.038
+         1        14         9    1045.0     0.038
+END PERIOD
+\end{lstlisting}
+
+As described earlier in the section on ``Block and Keyword Input,'' block information can be read from a separate text file.  To activate reading a list from separate text file, the first and only entry in the block must be a control line of the following form:  
+
+\begin{lstlisting}[style=blockdefinition]
+  OPEN/CLOSE <fname>
+\end{lstlisting}
+
+\noindent where \texttt{fname} is the name of the file containing the list.  Lists for the stress packages (CHD, WEL, DRN, RIV, GHB, RCH, and EVT) have an additional BINARY option.  The BINARY  option is not supported for the advanced stress packages (LAK, MAW, SFR, UZF, LKT, MWT, SFT, UZT).  The BINARY options is specified as follows:
+
+\begin{lstlisting}[style=blockdefinition]
+  OPEN/CLOSE <fname> [(BINARY)]
+\end{lstlisting}
+
+If the (BINARY) keyword is found on the control line, then the file is opened as an unformatted file on unit 99, and the list is read.  There are a number of requirements for using the (BINARY) option for lists.  All stress package lists begin with integer values for the \texttt{cellid} (layer, row, and column, for example).  These values must be represented as integer numbers in the unformatted file.  Also, all auxiliary data must be included in the binary file; auxiliary data must be represented as double precision numbers.  Lastly, the (BINARY) option does not support entry of \texttt{boundname}, and so the BOUNDNAMES option should not be activated in the OPTIONS block for the package.  
\ No newline at end of file
diff --git a/doc/mf6io/processing_of_input.tex b/doc/mf6io/framework/processing_of_input.tex
similarity index 56%
rename from doc/mf6io/processing_of_input.tex
rename to doc/mf6io/framework/processing_of_input.tex
index 3a5766cf204..6af3f1a933b 100644
--- a/doc/mf6io/processing_of_input.tex
+++ b/doc/mf6io/framework/processing_of_input.tex
@@ -1,43 +1,59 @@
 An effort is underway to process program input early in program runtime, before the simulation is created, in a general way that is not dependent on any given component.  This capability is called the \mf Input Data Processor (IDP).  Components that have been updated to use IDP no longer directly read or process file inputs but instead access input data from internally managed memory locations. 
 
-\subsection{Supported components}
+\subsection{Supported Components}
 
-A specific set of \mf components has been updated in the current version to use the Input Data Processor, as shown in Table~\ref{table:idmsupported}.  Two integration steps have been taken for each file type listed in the table.  First, IDP has been updated to support the reading and loading of variable input data for the component.  File types listed in the table, each previously read and processed by the component, are now processed by IDP.  Second, the component itself has been refactored to retrieve input from managed memory locations in a predictable way.  Components and associated file types shown in table~\ref{table:idmsupported} are described in more detail in later sections of this document.
+A specific set of \mf components has been updated in the current version to use the IDP routines, as shown in Table~\ref{table:idmsupported}.  Two integration steps have been taken for each file type listed in the table.  First, IDP has been updated to support the reading and loading of variable input data for the component.  File types listed in the table, each previously read and processed by the component, are now processed by IDP.  Second, the component itself has been refactored to retrieve input from managed memory locations in a predictable way.  Components and associated file types shown in table~\ref{table:idmsupported} are described in more detail in later sections of this document.
 
 \begin{table}[H]
-\caption{IDP integrated components}
+\caption{Components and subcomponents that are read using Input Data Processor (IDP) routines}
 \small
 \begin{center}
-\begin{tabular*}{\columnwidth}{l l l l}
+%\begin{tabular*}{\columnwidth}{l l}
+\begin{longtable}{p{6cm} p{4cm}}
 \hline
 \hline
-\textbf{Component Type} & \textbf{Subcomponent Type} & \textbf{Component} & \textbf{File Type} \\
+\textbf{Component / Subcomponent} & \textbf{File Type} \\
 \hline
-SIM & NAM & SIM/NAM & mfsim.nam \\
-GWF & NAM & GWF/NAM & GWF name file \\
-GWT & NAM & GWT/NAM & GWT name file \\
-GWF & DIS & GWF/DIS & DIS6 \\
-GWF & DISU & GWF/DISU & DISU6 \\
-GWF & DISV & GWF/DISV & DISV6 \\
-GWF & NPF & GWF/NPF & NPF6 \\
-GWT & DIS & GWT/DIS & DIS6 \\
-GWT & DISU & GWT/DISU & DISU6 \\
-GWT & DISV & GWT/DISV & DISV6 \\
-GWT & DSP & GWT/DSP & DSP6 \\
+SIM/NAM & mfsim.nam \\
+GWF/NAM & GWF name file \\
+GWT/NAM & GWT name file \\
+GWF/CHD & CHD6 \\
+GWF/DIS & DIS6 \\
+GWF/DISU & DISU6 \\
+GWF/DISV & DISV6 \\
+GWF/DRN & DRN6 \\
+GWF/EVT & EVT6 \\
+GWF/EVTA & EVT6 \\
+GWF/GHB & GHB6 \\
+GWF/IC & IC6 \\
+GWF/NPF & NPF6 \\
+GWF/RCH & RCH6 \\
+GWF/RCHA & RCH6 \\
+GWF/RIV & RIV6 \\
+GWF/WEL & WEL6 \\
+GWT/DIS & DIS6 \\
+GWT/DISU & DISU6 \\
+GWT/DISV & DISV6 \\
+GWT/CNC & CNC6 \\
+GWT/DSP & DSP6 \\
+GWT/IC & IC6 \\
+EXG/GWFGWF & GWF6-GWF6 \\
+EXG/GWFGWT & GWF6-GWT6 \\
+EXG/GWTGWT & GWT6-GWT6 \\
 \hline
-\end{tabular*}
+\end{longtable}
 \label{table:idmsupported}
 \end{center}
 \normalsize
 \end{table}
 
-\subsection{Scope of change}
+\subsection{Scope of Change}
 
 The Input Data Processor introduces transparent changes that are beyond the scope of this document.  Input logging differences, however, are readily apparent when comparing to earlier versions of \mf.  These differences are primarily related to timing as input files processed by IDP are read before the simulation has been created.  Logging appears in the simulation log (mfsim.lst) in part because simulation models and their associated listing files do not exist at the time when input is read.  In addition, input logging reflects only what was read and loaded to memory as further processing and use is deferred to the simulation components that the input is intended for.  Summaries of memory managed variables, including input data variables loaded by IDP, are possible to view in the simulation listing files with a Simulation Name File option described later. 
 
-\subsection{Example logging blocks}
+\subsection{Example of Logging}
 
-Below is example simulation logging (mfsim.lst) for two model package input files read and loaded by the Input Data Processor.  The first logging block results from processing a DIS6 input file and the second logging block results from processing an NPF6 input file.  Variable names in the blocks are described in later sections of this document.
+Below is an example of simulation logging (to the mfsim.lst output file) for two model package input files read and loaded by IDP routines.  The first logging block results from processing a DIS6 input file and the second logging block results from processing an NPF6 input file.  Variable names in the blocks are described in later sections of this document.
 
 \small
 \begin{lstlisting}[style=modeloutput]
diff --git a/doc/mf6io/gwf/bcoptions.tex b/doc/mf6io/gwf/bcoptions.tex
index 7f065154d24..939320b22c8 100644
--- a/doc/mf6io/gwf/bcoptions.tex
+++ b/doc/mf6io/gwf/bcoptions.tex
@@ -40,4 +40,6 @@
 
 \newcommand{\packageperioddescription}{All of the stress package information in the PERIOD block will continue to apply for subsequent stress periods until the end of the simulation, or until another PERIOD block is encountered.  When a new PERIOD block is encountered, all of the stresses from the previous block are replaced with the stresses in the new PERIOD block.  Note that this behavior is different from the advanced packages (MAW, SFR, LAK, and UZF).  To turn off all of the stresses for a stress period, a PERIOD block must be specified with no entries.  If a PERIOD block is not specified for the first stress period, then no stresses will be applied until the \texttt{iper} value of the first PERIOD block in the file.}
 
+\newcommand{\packageperioddescriptionarray}[1]{All of the stress package information in the PERIOD block will continue to apply for subsequent stress periods until the end of the simulation, or until another PERIOD block is encountered.  When a new PERIOD block is encountered, the array-based input specified by the user will replace the arrays currently in memory.  If an array is not specified in the period block, then that array will retain its present values in memory.  With the array-based input, the user must specify a {#1} rate of zero in order to turn {#1} off for a stress period.  This behavior is different from list-based input in which an empty PERIOD block results in no stresses being applied.}
+
 \newcommand{\advancedpackageperioddescription}[2]{All of the advanced stress package information in the PERIOD block will continue to apply for subsequent stress periods until the end of the simulation, or until another PERIOD block is encountered.  When a new PERIOD block is encountered only the {#2} specified in the new period block will be changed.  A {#1} not specified in the new period block will continue to behave according to its specification in the previous PERIOD block.  Note that this behavior is different from the simple stress packages (CHD, WEL, DRN, RIV, GHB, RCH and EVT), in which any stress not specified in a new PERIOD block will be removed.  To turn off all of the advanced stresses for a stress period, a PERIOD block must be specified with settings that deactivate the {#2}.  If a PERIOD block is not specified for the first stress period, then no stresses will be applied.}
diff --git a/doc/mf6io/gwf/evta.tex b/doc/mf6io/gwf/evta.tex
index 48c41bee52b..528d561d459 100644
--- a/doc/mf6io/gwf/evta.tex
+++ b/doc/mf6io/gwf/evta.tex
@@ -13,7 +13,7 @@ \subsubsection{Structure of Blocks}
 \vspace{5mm}
 \noindent \textit{FOR ANY STRESS PERIOD}
 \lstinputlisting[style=blockdefinition]{./mf6ivar/tex/gwf-evta-period.dat}
-\packageperioddescription
+\packageperioddescriptionarray{evapotranspiration}
 
 \vspace{5mm}
 \subsubsection{Explanation of Variables}
diff --git a/doc/mf6io/gwf/gwf.tex b/doc/mf6io/gwf/gwf.tex
index 452122446ef..3e3e77a8c5d 100644
--- a/doc/mf6io/gwf/gwf.tex
+++ b/doc/mf6io/gwf/gwf.tex
@@ -11,8 +11,6 @@
 \subsection{Information for Existing MODFLOW Users}
 \input{gwf/info_existing_users.tex}
 
-\input{gwf/array_data.tex}
-
 \subsection{Units of Length and Time}
 The GWF Model formulates the groundwater flow equation without using prescribed length and time units. Any consistent units of length and time can be used when specifying the input data for a simulation. This capability gives a certain amount of freedom to the user, but care must be exercised to avoid mixing units.  The program cannot detect the use of inconsistent units.  For example, if hydraulic conductivity is entered in units of feet per day and pumpage as cubic meters per second, the program will run, but the results will be meaningless. Other processes generally are expected to work with consistent length and time units; however, other processes could conceivably place restrictions on which units are supported.
 
diff --git a/doc/mf6io/gwf/rcha.tex b/doc/mf6io/gwf/rcha.tex
index bfd5f8e3906..3b9180d48e6 100644
--- a/doc/mf6io/gwf/rcha.tex
+++ b/doc/mf6io/gwf/rcha.tex
@@ -14,7 +14,7 @@ \subsubsection{Structure of Blocks}
 \vspace{5mm}
 \noindent \textit{FOR ANY STRESS PERIOD}
 \lstinputlisting[style=blockdefinition]{./mf6ivar/tex/gwf-rcha-period.dat}
-\packageperioddescription
+\packageperioddescriptionarray{recharge}
 
 \vspace{5mm}
 \subsubsection{Explanation of Variables}
diff --git a/doc/mf6io/mf6ivar/deprecations.py b/doc/mf6io/mf6ivar/deprecations.py
new file mode 100644
index 00000000000..52a9e683081
--- /dev/null
+++ b/doc/mf6io/mf6ivar/deprecations.py
@@ -0,0 +1,52 @@
+import os
+from typing import List, Tuple, Optional
+from packaging.version import Version
+from pathlib import Path
+
+
+def get_deprecations(dfndir) -> List[Tuple[Path, str, Version, Optional[Version]]]:
+    dfns = Path(dfndir).rglob("*.dfn")
+    deps = {}
+    for dfn in dfns:
+        with open(dfn, "r") as f:
+            name = None
+            for line in f:
+                if line.startswith("#"):
+                    continue
+                keys = ["deprecated", "removed"]
+                ikeys = {k: i for i, k in enumerate(keys)}
+                for key in keys:
+                    if line.startswith("name"):
+                        name = line.split()[1]
+                    if line.startswith(key):
+                        val = deps.get((dfn, key), [None, None])
+                        key, ver = line.split()
+                        ik = ikeys[key]
+                        val[ik] = val[ik] if val[ik] else Version(ver)
+                        deps[(dfn, name)] = val
+
+    return [(file, key, dep, rem) for (file, key), (dep, rem) in deps.items()]
+
+
+def create_deprecations_file(dfndir, mddir, verbose):
+    deprecations = get_deprecations(dfndir)
+    deps_path = (Path(mddir) / 'deprecations.md').absolute()
+    if verbose:
+        print(f"Found {len(deprecations)} deprecations, writing {deps_path}")
+    with open(deps_path, "w") as f:
+        s = "#### Deprecations\n\n"
+        s += "The following table lists deprecated options and the versions in which they were deprecated and (optionally) removed.\n\n"
+        if any(deprecations):
+            s += "| Model-Package | Option | Deprecated | Removed |\n"
+            s += "|:--------------|:-------|:-----------|:--------|\n"
+            for (file, option, deprecated, removed) in deprecations:
+                s += f"| {file.stem} | {option} | {deprecated} | {removed if removed else ''} |\n"
+            if len(s) > 0:
+                s += "\n"
+        f.write(s)
+
+
+if __name__ == '__main__':
+    dfndir = os.path.join('.', 'dfn')
+    mddir = os.path.join('.', 'md')
+    create_deprecations_file(dfndir, mddir, verbose=True)
diff --git a/doc/mf6io/mf6ivar/dfn/exg-gwfgwf.dfn b/doc/mf6io/mf6ivar/dfn/exg-gwfgwf.dfn
index 66ce83bced2..2232bfbdf90 100644
--- a/doc/mf6io/mf6ivar/dfn/exg-gwfgwf.dfn
+++ b/doc/mf6io/mf6ivar/dfn/exg-gwfgwf.dfn
@@ -26,6 +26,7 @@ reader urword
 optional true
 longname keyword to print input to list file
 description keyword to indicate that the list of exchange entries will be echoed to the listing file immediately after it is read.
+mf6internal iprpak
 
 block options
 name print_flows
@@ -34,6 +35,7 @@ reader urword
 optional true
 longname keyword to print gwfgwf flows to list file
 description keyword to indicate that the list of exchange flow rates will be printed to the listing file for every stress period in which ``SAVE BUDGET'' is specified in Output Control.
+mf6internal iprflow
 
 block options
 name save_flows
@@ -42,6 +44,7 @@ reader urword
 optional true
 longname keyword to save GWFGWF flows
 description keyword to indicate that cell-by-cell flow terms will be written to the budget file for each model provided that the Output Control for the models are set up with the ``BUDGET SAVE FILE'' option.
+mf6internal ipakcb
 
 block options
 name cell_averaging
@@ -207,6 +210,7 @@ reader urword
 optional true
 longname activate interface model on exchange
 description activates the interface model mechanism for calculating the coefficients at (and possibly near) the exchange. This keyword should only be used for development purposes.
+mf6internal dev_ifmod_on
 
 # --------------------- exg gwfgwf dimensions ---------------------
 
@@ -224,6 +228,7 @@ description keyword and integer value specifying the number of GWF-GWF exchanges
 block exchangedata
 name exchangedata
 type recarray cellidm1 cellidm2 ihc cl1 cl2 hwva aux boundname
+shape (nexg)
 reader urword
 optional false
 longname exchange data
diff --git a/doc/mf6io/mf6ivar/dfn/exg-gwtgwt.dfn b/doc/mf6io/mf6ivar/dfn/exg-gwtgwt.dfn
index f7956f73687..f5aeb241996 100644
--- a/doc/mf6io/mf6ivar/dfn/exg-gwtgwt.dfn
+++ b/doc/mf6io/mf6ivar/dfn/exg-gwtgwt.dfn
@@ -42,6 +42,7 @@ reader urword
 optional true
 longname keyword to print input to list file
 description keyword to indicate that the list of exchange entries will be echoed to the listing file immediately after it is read.
+mf6internal iprpak
 
 block options
 name print_flows
@@ -50,6 +51,7 @@ reader urword
 optional true
 longname keyword to print gwfgwf flows to list file
 description keyword to indicate that the list of exchange flow rates will be printed to the listing file for every stress period in which ``SAVE BUDGET'' is specified in Output Control.
+mf6internal iprflow
 
 block options
 name save_flows
@@ -58,6 +60,7 @@ reader urword
 optional true
 longname keyword to save GWFGWF flows
 description keyword to indicate that cell-by-cell flow terms will be written to the budget file for each model provided that the Output Control for the models are set up with the ``BUDGET SAVE FILE'' option.
+mf6internal ipakcb
 
 block options
 name adv_scheme
@@ -168,6 +171,7 @@ reader urword
 optional true
 longname activate interface model on exchange
 description activates the interface model mechanism for calculating the coefficients at (and possibly near) the exchange. This keyword should only be used for development purposes.
+mf6internal dev_ifmod_on
 
 # --------------------- exg gwtgwt dimensions ---------------------
 
@@ -185,6 +189,7 @@ description keyword and integer value specifying the number of GWT-GWT exchanges
 block exchangedata
 name exchangedata
 type recarray cellidm1 cellidm2 ihc cl1 cl2 hwva aux boundname
+shape (nexg)
 reader urword
 optional false
 longname exchange data
diff --git a/doc/mf6io/mf6ivar/dfn/gwf-chd.dfn b/doc/mf6io/mf6ivar/dfn/gwf-chd.dfn
index 543433c1b3c..56e3ca306a9 100644
--- a/doc/mf6io/mf6ivar/dfn/gwf-chd.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwf-chd.dfn
@@ -1,5 +1,6 @@
 # --------------------- gwf chd options ---------------------
 # flopy multi-package
+# package-type stress-package
 
 block options
 name auxiliary
@@ -35,6 +36,7 @@ reader urword
 optional true
 longname print input to listing file
 description REPLACE print_input {'{#1}': 'constant-head'}
+mf6internal iprpak
 
 block options
 name print_flows
@@ -43,6 +45,7 @@ reader urword
 optional true
 longname print CHD flows to listing file
 description REPLACE print_flows {'{#1}': 'constant-head'}
+mf6internal iprflow
 
 block options
 name save_flows
@@ -51,6 +54,7 @@ reader urword
 optional true
 longname save CHD flows to budget file
 description REPLACE save_flows {'{#1}': 'constant-head'}
+mf6internal ipakcb
 
 block options
 name ts_filerecord
@@ -127,6 +131,15 @@ optional false
 longname obs6 input filename
 description REPLACE obs6_filename {'{#1}': 'constant-head'}
 
+# dev options
+block options
+name dev_no_newton
+type keyword
+reader urword
+optional true
+longname turn off Newton for unconfined cells
+description turn off Newton for unconfined cells
+mf6internal inewton
 
 # --------------------- gwf chd dimensions ---------------------
 
@@ -161,6 +174,7 @@ shape (maxbound)
 reader urword
 longname
 description
+mf6internal spd
 
 block period
 name cellid
@@ -194,6 +208,7 @@ optional true
 time_series true
 longname auxiliary variables
 description REPLACE aux {'{#1}': 'constant head'}
+mf6internal auxvar
 
 block period
 name boundname
diff --git a/doc/mf6io/mf6ivar/dfn/gwf-disu.dfn b/doc/mf6io/mf6ivar/dfn/gwf-disu.dfn
index 8c131363e2f..48e18477c1c 100644
--- a/doc/mf6io/mf6ivar/dfn/gwf-disu.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwf-disu.dfn
@@ -176,7 +176,7 @@ name vertices
 type recarray iv xv yv
 shape (nvert)
 reader urword
-optional false
+optional true
 longname vertices data
 description
 
@@ -219,7 +219,7 @@ name cell2d
 type recarray icell2d xc yc ncvert icvert
 shape (nodes)
 reader urword
-optional false
+optional true
 longname cell2d data
 description
 
diff --git a/doc/mf6io/mf6ivar/dfn/gwf-drn.dfn b/doc/mf6io/mf6ivar/dfn/gwf-drn.dfn
index c03a1078000..e88cc6f43c9 100644
--- a/doc/mf6io/mf6ivar/dfn/gwf-drn.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwf-drn.dfn
@@ -1,5 +1,6 @@
 # --------------------- gwf drn options ---------------------
 # flopy multi-package
+# package-type stress-package
 
 block options
 name auxiliary
@@ -44,6 +45,7 @@ reader urword
 optional true
 longname print input to listing file
 description REPLACE print_input {'{#1}': 'drain'}
+mf6internal iprpak
 
 block options
 name print_flows
@@ -52,6 +54,7 @@ reader urword
 optional true
 longname print calculated flows to listing file
 description REPLACE print_flows {'{#1}': 'drain'}
+mf6internal iprflow
 
 block options
 name save_flows
@@ -60,6 +63,7 @@ reader urword
 optional true
 longname save CHD flows to budget file
 description REPLACE save_flows {'{#1}': 'drain'}
+mf6internal ipakcb
 
 block options
 name ts_filerecord
@@ -145,6 +149,16 @@ optional true
 longname
 description REPLACE mover {'{#1}': 'Drain'}
 
+# dev options
+block options
+name dev_cubic_scaling
+type keyword
+reader urword
+optional true
+longname cubic-scaling
+description cubic-scaling is used to scale the drain conductance
+mf6internal icubicsfac
+
 # --------------------- gwf drn dimensions ---------------------
 
 block dimensions
@@ -178,6 +192,7 @@ shape (maxbound)
 reader urword
 longname
 description
+mf6internal spd
 
 block period
 name cellid
@@ -222,6 +237,7 @@ optional true
 time_series true
 longname auxiliary variables
 description REPLACE aux {'{#1}': 'drain'}
+mf6internal auxvar
 
 block period
 name boundname
diff --git a/doc/mf6io/mf6ivar/dfn/gwf-evt.dfn b/doc/mf6io/mf6ivar/dfn/gwf-evt.dfn
index b66f62301c8..33f5a971611 100644
--- a/doc/mf6io/mf6ivar/dfn/gwf-evt.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwf-evt.dfn
@@ -1,5 +1,6 @@
 # --------------------- gwf evt options ---------------------
 # flopy multi-package
+# package-type stress-package
 
 block options
 name fixed_cell
@@ -44,6 +45,7 @@ reader urword
 optional true
 longname print input to listing file
 description REPLACE print_input {'{#1}': 'evapotranspiration'}
+mf6internal iprpak
 
 block options
 name print_flows
@@ -52,6 +54,7 @@ reader urword
 optional true
 longname print evapotranspiration rates to listing file
 description REPLACE print_flows {'{#1}': 'evapotranspiration'}
+mf6internal iprflow
 
 block options
 name save_flows
@@ -60,6 +63,7 @@ reader urword
 optional true
 longname save evapotranspiration rates to budget file
 description REPLACE save_flows {'{#1}': 'evapotranspiration'}
+mf6internal ipakcb
 
 block options
 name ts_filerecord
@@ -143,6 +147,7 @@ reader urword
 optional true
 longname specify proportion of evapotranspiration rate at ET surface
 description indicates that the proportion of the evapotranspiration rate at the ET surface will be specified as PETM0 in list input.
+mf6internal surfratespec
 
 # --------------------- gwf evt dimensions ---------------------
 
@@ -184,6 +189,7 @@ shape (maxbound)
 reader urword
 longname
 description
+mf6internal spd
 
 block period
 name cellid
@@ -235,6 +241,7 @@ shape (nseg-1)
 tagged false
 in_record true
 reader urword
+optional true
 time_series true
 longname proportion of ET extinction depth
 description is the proportion of the ET extinction depth at the bottom of a segment (dimensionless). pxdp is an array of size (nseg - 1).  Values in pxdp must be greater than 0.0 and less than 1.0.  pxdp values for a cell must increase monotonically.  If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value.
@@ -246,6 +253,7 @@ shape (nseg-1)
 tagged false
 in_record true
 reader urword
+optional true
 time_series true
 longname proportion of maximum ET rate
 description is the proportion of the maximum ET flux rate at the bottom of a segment (dimensionless). petm is an array of size (nseg - 1).  If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value.
@@ -273,6 +281,7 @@ optional true
 time_series true
 longname auxiliary variables
 description REPLACE aux {'{#1}': 'evapotranspiration'}
+mf6internal auxvar
 
 block period
 name boundname
diff --git a/doc/mf6io/mf6ivar/dfn/gwf-evta.dfn b/doc/mf6io/mf6ivar/dfn/gwf-evta.dfn
index 19ca3cec45a..2dc966cb436 100644
--- a/doc/mf6io/mf6ivar/dfn/gwf-evta.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwf-evta.dfn
@@ -1,5 +1,6 @@
 # --------------------- gwf evta options ---------------------
 # flopy multi-package
+# package-type stress-package
 
 block options
 name readasarrays
@@ -45,6 +46,7 @@ reader urword
 optional true
 longname print input to listing file
 description REPLACE print_input {'{#1}': 'evapotranspiration'}
+mf6internal iprpak
 
 block options
 name print_flows
@@ -53,6 +55,7 @@ reader urword
 optional true
 longname print evapotranspiration rates to listing file
 description REPLACE print_flows {'{#1}': 'evapotranspiration'}
+mf6internal iprflow
 
 block options
 name save_flows
@@ -61,6 +64,7 @@ reader urword
 optional true
 longname save CHD flows to budget file
 description REPLACE save_flows {'{#1}': 'evapotranspiration'}
+mf6internal ipakcb
 
 block options
 name tas_filerecord
@@ -177,6 +181,7 @@ name rate
 type double precision
 shape (ncol*nrow; ncpl)
 reader readarray
+time_series true
 longname evapotranspiration surface
 description is the maximum ET flux rate ($LT^{-1}$).
 default_value 1.e-3
@@ -191,9 +196,11 @@ description is the ET extinction depth ($L$).
 default_value 1.0
 
 block period
-name aux(iaux)
+name aux
 type double precision
 shape (ncol*nrow; ncpl)
 reader readarray
+time_series true
 longname auxiliary variable iaux
 description is an array of values for auxiliary variable AUX(IAUX), where iaux is a value from 1 to NAUX, and AUX(IAUX) must be listed as part of the auxiliary variables.  A separate array can be specified for each auxiliary variable.  If an array is not specified for an auxiliary variable, then a value of zero is assigned.  If the value specified here for the auxiliary variable is the same as auxmultname, then the evapotranspiration rate will be multiplied by this array.
+mf6internal auxvar
diff --git a/doc/mf6io/mf6ivar/dfn/gwf-ghb.dfn b/doc/mf6io/mf6ivar/dfn/gwf-ghb.dfn
index f84a3708692..c97c78804b3 100644
--- a/doc/mf6io/mf6ivar/dfn/gwf-ghb.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwf-ghb.dfn
@@ -1,5 +1,6 @@
 # --------------------- gwf ghb options ---------------------
 # flopy multi-package
+# package-type stress-package
 
 block options
 name auxiliary
@@ -35,6 +36,7 @@ reader urword
 optional true
 longname print input to listing file
 description REPLACE print_input {'{#1}': 'general-head boundary'}
+mf6internal iprpak
 
 block options
 name print_flows
@@ -43,6 +45,7 @@ reader urword
 optional true
 longname print calculated flows to listing file
 description REPLACE print_flows {'{#1}': 'general-head boundary'}
+mf6internal iprflow
 
 block options
 name save_flows
@@ -51,6 +54,7 @@ reader urword
 optional true
 longname save CHD flows to budget file
 description REPLACE save_flows {'{#1}': 'general-head boundary'}
+mf6internal ipakcb
 
 block options
 name ts_filerecord
@@ -169,6 +173,7 @@ shape (maxbound)
 reader urword
 longname
 description
+mf6internal spd
 
 block period
 name cellid
@@ -213,6 +218,7 @@ optional true
 time_series true
 longname auxiliary variables
 description REPLACE aux {'{#1}': 'general-head boundary'}
+mf6internal auxvar
 
 block period
 name boundname
diff --git a/doc/mf6io/mf6ivar/dfn/gwf-lak.dfn b/doc/mf6io/mf6ivar/dfn/gwf-lak.dfn
index 36a67c16dca..3dc9e940c0b 100644
--- a/doc/mf6io/mf6ivar/dfn/gwf-lak.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwf-lak.dfn
@@ -1,5 +1,6 @@
 # --------------------- gwf lak options ---------------------
 # flopy multi-package
+# package-type advanced-stress-package
 
 block options
 name auxiliary
@@ -349,21 +350,21 @@ description value specifying the number of lakes tables that will be used to def
 
 block packagedata
 name packagedata
-type recarray lakeno strt nlakeconn aux boundname
+type recarray ifno strt nlakeconn aux boundname
 shape (maxbound)
 reader urword
 longname
 description
 
 block packagedata
-name lakeno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname lake number for this entry
-description integer value that defines the lake number associated with the specified PACKAGEDATA data on the line. LAKENO must be greater than zero and less than or equal to NLAKES. Lake information must be specified for every lake or the program will terminate with an error.  The program will also terminate with an error if information for a lake is specified more than once.
+description integer value that defines the feature (lake) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NLAKES. Lake information must be specified for every lake or the program will terminate with an error.  The program will also terminate with an error if information for a lake is specified more than once.
 numeric_index true
 
 block packagedata
@@ -384,7 +385,7 @@ tagged false
 in_record true
 reader urword
 longname number of lake connections
-description integer value that defines the number of GWF cells connected to this (LAKENO) lake. There can only be one vertical lake connection to each GWF cell. NLAKECONN must be greater than zero.
+description integer value that defines the number of GWF cells connected to this (IFNO) lake. There can only be one vertical lake connection to each GWF cell. NLAKECONN must be greater than zero.
 
 block packagedata
 name aux
@@ -414,21 +415,21 @@ description REPLACE boundname {'{#1}': 'lake'}
 
 block connectiondata
 name connectiondata
-type recarray lakeno iconn cellid claktype bedleak belev telev connlen connwidth
+type recarray ifno iconn cellid claktype bedleak belev telev connlen connwidth
 shape (sum(nlakeconn))
 reader urword
 longname
 description
 
 block connectiondata
-name lakeno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname lake number for this entry
-description integer value that defines the lake number associated with the specified CONNECTIONDATA data on the line. LAKENO must be greater than zero and less than or equal to NLAKES. Lake connection information must be specified for every lake connection to the GWF model (NLAKECONN) or the program will terminate with an error.  The program will also terminate with an error if connection information for a lake connection to the GWF model is specified more than once.
+description integer value that defines the feature (lake) number associated with the specified CONNECTIONDATA data on the line. IFNO must be greater than zero and less than or equal to NLAKES. Lake connection information must be specified for every lake connection to the GWF model (NLAKECONN) or the program will terminate with an error.  The program will also terminate with an error if connection information for a lake connection to the GWF model is specified more than once.
 numeric_index true
 
 block connectiondata
@@ -439,7 +440,7 @@ tagged false
 in_record true
 reader urword
 longname connection number for this entry
-description integer value that defines the GWF connection number for this lake connection entry. ICONN must be greater than zero and less than or equal to NLAKECONN for lake LAKENO.
+description integer value that defines the GWF connection number for this lake connection entry. ICONN must be greater than zero and less than or equal to NLAKECONN for lake IFNO.
 numeric_index true
 
 block connectiondata
@@ -470,7 +471,7 @@ tagged false
 in_record true
 reader urword
 longname bed leakance
-description character string or real value that defines the bed leakance for the lake-GWF connection. BEDLEAK must be greater than or equal to zero or specified to be NONE. If BEDLEAK is specified to be NONE, the lake-GWF connection conductance is solely a function of aquifer properties in the connected GWF cell and lakebed sediments are assumed to be absent.
+description real value or character string that defines the bed leakance for the lake-GWF connection. BEDLEAK must be greater than or equal to zero, equal to the DNODATA value (3.0E+30), or specified to be NONE. If DNODATA or NONE is specified for BEDLEAK, the lake-GWF connection conductance is solely a function of aquifer properties in the connected GWF cell and lakebed sediments are assumed to be absent. Warning messages will be issued if NONE is specified. Eventually the ability to specify NONE will be deprecated and cause MODFLOW 6 to terminate with an error.
 
 block connectiondata
 name belev
@@ -517,21 +518,21 @@ description real value that defines the connection face width for a HORIZONTAL l
 
 block tables
 name tables
-type recarray lakeno tab6 filein tab6_filename
+type recarray ifno tab6 filein tab6_filename
 shape (ntables)
 reader urword
 longname
 description
 
 block tables
-name lakeno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname lake number for this entry
-description integer value that defines the lake number associated with the specified TABLES data on the line. LAKENO must be greater than zero and less than or equal to NLAKES. The program will terminate with an error if table information for a lake is specified more than once or the number of specified tables is less than NTABLES.
+description integer value that defines the feature (lake) number associated with the specified TABLES data on the line. IFNO must be greater than zero and less than or equal to NLAKES. The program will terminate with an error if table information for a lake is specified more than once or the number of specified tables is less than NTABLES.
 numeric_index true
 
 block tables
@@ -796,7 +797,7 @@ in_record true
 reader urword
 time_series true
 longname extraction rate
-description real or character value that defines the extraction rate for the lake outflow. A positive value indicates inflow and a negative value indicates outflow from the lake. RATE only applies to active (IBOUND $>$ 0) lakes. A specified RATE is only applied if COUTTYPE for the OUTLETNO is SPECIFIED. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. By default, the RATE for each SPECIFIED lake outlet is zero.
+description real or character value that defines the extraction rate for the lake outflow. A positive value indicates inflow and a negative value indicates outflow from the lake. RATE only applies to outlets associated with active lakes (STATUS is ACTIVE). A specified RATE is only applied if COUTTYPE for the OUTLETNO is SPECIFIED. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. By default, the RATE for each SPECIFIED lake outlet is zero.
 
 block period
 name invert
diff --git a/doc/mf6io/mf6ivar/dfn/gwf-maw.dfn b/doc/mf6io/mf6ivar/dfn/gwf-maw.dfn
index bf64974c4a0..2e957ec2c82 100644
--- a/doc/mf6io/mf6ivar/dfn/gwf-maw.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwf-maw.dfn
@@ -1,5 +1,6 @@
 # --------------------- gwf maw options ---------------------
 # flopy multi-package
+# package-type advanced-stress-package
 
 block options
 name auxiliary
@@ -334,21 +335,21 @@ description integer value specifying the number of multi-aquifer wells that will
 
 block packagedata
 name packagedata
-type recarray wellno radius bottom strt condeqn ngwfnodes aux boundname
+type recarray ifno radius bottom strt condeqn ngwfnodes aux boundname
 shape (nmawwells)
 reader urword
 longname
 description
 
 block packagedata
-name wellno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname well number for this entry
-description integer value that defines the well number associated with the specified PACKAGEDATA data on the line. WELLNO must be greater than zero and less than or equal to NMAWWELLS. Multi-aquifer well information must be specified for every multi-aquifer well or the program will terminate with an error.  The program will also terminate with an error if information for a multi-aquifer well is specified more than once.
+description integer value that defines the feature (well) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NMAWWELLS. Multi-aquifer well information must be specified for every multi-aquifer well or the program will terminate with an error.  The program will also terminate with an error if information for a multi-aquifer well is specified more than once.
 numeric_index true
 
 block packagedata
@@ -399,7 +400,7 @@ tagged false
 in_record true
 reader urword
 longname number of connected GWF cells
-description integer value that defines the number of GWF nodes connected to this (WELLNO) multi-aquifer well. NGWFNODES must be greater than zero.
+description integer value that defines the number of GWF nodes connected to this (IFNO) multi-aquifer well. NGWFNODES must be greater than zero.
 
 block packagedata
 name aux
@@ -429,20 +430,20 @@ description REPLACE boundname {'{#1}': 'multi-aquifer well'}
 
 block connectiondata
 name connectiondata
-type recarray wellno icon cellid scrn_top scrn_bot hk_skin radius_skin
+type recarray ifno icon cellid scrn_top scrn_bot hk_skin radius_skin
 reader urword
 longname
 description
 
 block connectiondata
-name wellno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname well number for this entry
-description integer value that defines the well number associated with the specified CONNECTIONDATA data on the line. WELLNO must be greater than zero and less than or equal to NMAWWELLS. Multi-aquifer well connection information must be specified for every multi-aquifer well connection to the GWF model (NGWFNODES) or the program will terminate with an error.  The program will also terminate with an error if connection information for a multi-aquifer well connection to the GWF model is specified more than once.
+description integer value that defines the feature (well) number associated with the specified CONNECTIONDATA data on the line. IFNO must be greater than zero and less than or equal to NMAWWELLS. Multi-aquifer well connection information must be specified for every multi-aquifer well connection to the GWF model (NGWFNODES) or the program will terminate with an error.  The program will also terminate with an error if connection information for a multi-aquifer well connection to the GWF model is specified more than once.
 numeric_index true
 
 block connectiondata
@@ -453,7 +454,7 @@ tagged false
 in_record true
 reader urword
 longname connection number
-description integer value that defines the GWF connection number for this multi-aquifer well connection entry. ICONN must be greater than zero and less than or equal to NGWFNODES for multi-aquifer well WELLNO.
+description integer value that defines the GWF connection number for this multi-aquifer well connection entry. ICONN must be greater than zero and less than or equal to NGWFNODES for multi-aquifer well IFNO.
 numeric_index true
 
 block connectiondata
@@ -484,7 +485,7 @@ tagged false
 in_record true
 reader urword
 longname screen bottom
-description value that defines the bottom elevation of the screen for the multi-aquifer well connection. If CONDEQN is SPECIFIED, THIEM, SKIN, or COMPOSITE, SCRN\_BOT can be any value is set to the bottom of the cell. If CONDEQN is MEAN, SCRN\_BOT is set to the multi-aquifer well connection cell bottom if the specified value is less than the cell bottom. The program will terminate with an error if the screen bottom is greater than the screen top.
+description value that defines the bottom elevation of the screen for the multi-aquifer well connection. If CONDEQN is SPECIFIED, THIEM, SKIN, or COMPOSITE, SCRN\_BOT can be any value and is set to the bottom of the cell. If CONDEQN is MEAN, SCRN\_BOT is set to the multi-aquifer well connection cell bottom if the specified value is less than the cell bottom. The program will terminate with an error if the screen bottom is greater than the screen top.
 
 block connectiondata
 name hk_skin
@@ -524,21 +525,21 @@ description REPLACE iper {}
 
 block period
 name perioddata
-type recarray wellno mawsetting
+type recarray ifno mawsetting
 shape
 reader urword
 longname
 description
 
 block period
-name wellno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname well number for this entry
-description integer value that defines the well number associated with the specified PERIOD data on the line. WELLNO must be greater than zero and less than or equal to NMAWWELLS.
+description integer value that defines the well number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NMAWWELLS.
 numeric_index true
 
 block period
@@ -619,7 +620,7 @@ in_record true
 reader urword
 time_series true
 longname well pumping rate
-description is the volumetric pumping rate for the multi-aquifer well. A positive value indicates recharge and a negative value indicates discharge (pumping). RATE only applies to active (IBOUND $>$ 0) multi-aquifer wells. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. By default, the RATE for each multi-aquifer well is zero.
+description is the volumetric pumping rate for the multi-aquifer well. A positive value indicates recharge and a negative value indicates discharge (pumping). RATE only applies to active (STATUS is ACTIVE) multi-aquifer wells. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. By default, the RATE for each multi-aquifer well is zero.
 
 block period
 name well_head
diff --git a/doc/mf6io/mf6ivar/dfn/gwf-rch.dfn b/doc/mf6io/mf6ivar/dfn/gwf-rch.dfn
index 0a36ae078be..da53c849863 100644
--- a/doc/mf6io/mf6ivar/dfn/gwf-rch.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwf-rch.dfn
@@ -1,5 +1,6 @@
 # --------------------- gwf rch options ---------------------
 # flopy multi-package
+# package-type stress-package
 
 block options
 name fixed_cell
@@ -44,6 +45,7 @@ reader urword
 optional true
 longname print input to listing file
 description REPLACE print_input {'{#1}': 'recharge'}
+mf6internal iprpak
 
 block options
 name print_flows
@@ -52,6 +54,7 @@ reader urword
 optional true
 longname print recharge rates to listing file
 description REPLACE print_flows {'{#1}': 'recharge'}
+mf6internal iprflow
 
 block options
 name save_flows
@@ -60,6 +63,7 @@ reader urword
 optional true
 longname save recharge to budget file
 description REPLACE save_flows {'{#1}': 'recharge'}
+mf6internal ipakcb
 
 block options
 name ts_filerecord
@@ -169,6 +173,7 @@ shape (maxbound)
 reader urword
 longname
 description
+mf6internal spd
 
 block period
 name cellid
@@ -202,6 +207,7 @@ optional true
 time_series true
 longname auxiliary variables
 description REPLACE aux {'{#1}': 'recharge'}
+mf6internal auxvar
 
 block period
 name boundname
diff --git a/doc/mf6io/mf6ivar/dfn/gwf-rcha.dfn b/doc/mf6io/mf6ivar/dfn/gwf-rcha.dfn
index bc5874ef599..a0fb9ec0f60 100644
--- a/doc/mf6io/mf6ivar/dfn/gwf-rcha.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwf-rcha.dfn
@@ -1,5 +1,6 @@
 # --------------------- gwf rcha options ---------------------
 # flopy multi-package
+# package-type stress-package
 
 block options
 name readasarrays
@@ -45,6 +46,7 @@ reader urword
 optional true
 longname print input to listing file
 description REPLACE print_input {'{#1}': 'recharge'}
+mf6internal iprpak
 
 block options
 name print_flows
@@ -53,6 +55,7 @@ reader urword
 optional true
 longname print recharge rates to listing file
 description REPLACE print_flows {'{#1}': 'recharge'}
+mf6internal iprflow
 
 block options
 name save_flows
@@ -61,6 +64,7 @@ reader urword
 optional true
 longname save CHD flows to budget file
 description REPLACE save_flows {'{#1}': 'recharge'}
+mf6internal ipakcb
 
 block options
 name tas_filerecord
@@ -103,7 +107,7 @@ reader urword
 optional false
 tagged false
 longname file name of time series information
-description defines a time-array-series file defining a time-array series that can be used to assign time-varying values. See the Time-Variable Input section for instructions on using the time-array series capability.
+description defines a time-array-series file defining a time-array series that can be used to assign time-varying values. See the ``Time-Variable Input'' section for instructions on using the time-array series capability.
 
 block options
 name obs_filerecord
@@ -168,6 +172,7 @@ name recharge
 type double precision
 shape (ncol*nrow; ncpl)
 reader readarray
+time_series true
 longname recharge rate
 description is the recharge flux rate ($LT^{-1}$).  This rate is multiplied inside the program by the surface area of the cell to calculate the volumetric recharge rate. The recharge array may be defined by a time-array series (see the "Using Time-Array Series in a Package" section).
 default_value 1.e-3
@@ -177,6 +182,8 @@ name aux
 type double precision
 shape (ncol*nrow; ncpl)
 reader readarray
+time_series true
 optional true
 longname auxiliary variable iaux
 description is an array of values for auxiliary variable aux(iaux), where iaux is a value from 1 to naux, and aux(iaux) must be listed as part of the auxiliary variables.  A separate array can be specified for each auxiliary variable.  If an array is not specified for an auxiliary variable, then a value of zero is assigned.  If the value specified here for the auxiliary variable is the same as auxmultname, then the recharge array will be multiplied by this array.
+mf6internal auxvar
diff --git a/doc/mf6io/mf6ivar/dfn/gwf-riv.dfn b/doc/mf6io/mf6ivar/dfn/gwf-riv.dfn
index a57b653cc0c..fca586f17eb 100644
--- a/doc/mf6io/mf6ivar/dfn/gwf-riv.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwf-riv.dfn
@@ -1,5 +1,6 @@
 # --------------------- gwf riv options ---------------------
 # flopy multi-package
+# package-type stress-package
 
 block options
 name auxiliary
@@ -35,6 +36,7 @@ reader urword
 optional true
 longname print input to listing file
 description REPLACE print_input {'{#1}': 'river'}
+mf6internal iprpak
 
 block options
 name print_flows
@@ -43,6 +45,7 @@ reader urword
 optional true
 longname print calculated flows to listing file
 description REPLACE print_flows {'{#1}': 'river'}
+mf6internal iprflow
 
 block options
 name save_flows
@@ -51,6 +54,7 @@ reader urword
 optional true
 longname save CHD flows to budget file
 description REPLACE save_flows {'{#1}': 'river'}
+mf6internal ipakcb
 
 block options
 name ts_filerecord
@@ -169,6 +173,7 @@ shape (maxbound)
 reader urword
 longname
 description
+mf6internal spd
 
 block period
 name cellid
@@ -224,6 +229,7 @@ optional true
 time_series true
 longname auxiliary variables
 description REPLACE aux {'{#1}': 'river'}
+mf6internal auxvar
 
 block period
 name boundname
diff --git a/doc/mf6io/mf6ivar/dfn/gwf-sfr.dfn b/doc/mf6io/mf6ivar/dfn/gwf-sfr.dfn
index 5a23b919e45..24da890760e 100644
--- a/doc/mf6io/mf6ivar/dfn/gwf-sfr.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwf-sfr.dfn
@@ -1,5 +1,6 @@
 # --------------------- gwf sfr options ---------------------
 # flopy multi-package
+# package-type advanced-stress-package
 
 block options
 name auxiliary
@@ -342,21 +343,21 @@ description integer value specifying the number of stream reaches.  There must b
 
 block packagedata
 name packagedata
-type recarray rno cellid rlen rwid rgrd rtp rbth rhk man ncon ustrf ndv aux boundname
+type recarray ifno cellid rlen rwid rgrd rtp rbth rhk man ncon ustrf ndv aux boundname
 shape (maxbound)
 reader urword
 longname
 description
 
 block packagedata
-name rno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname reach number for this entry
-description integer value that defines the reach number associated with the specified PACKAGEDATA data on the line. RNO must be greater than zero and less than or equal to NREACHES. Reach information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if information for a reach is specified more than once.
+description integer value that defines the feature (reach) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NREACHES. Reach information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if information for a reach is specified more than once.
 numeric_index true
 
 block packagedata
@@ -367,7 +368,7 @@ tagged false
 in_record true
 reader urword
 longname cell identifier
-description The keyword `NONE' must be specified for reaches that are not connected to an underlying GWF cell. The keyword `NONE' is used for reaches that are in cells that have IDOMAIN values less than one or are in areas not covered by the GWF model grid. Reach-aquifer flow is not calculated if the keyword `NONE' is specified.
+description is the cell identifier, and depends on the type of grid that is used for the simulation. For a structured grid that uses the DIS input file, CELLID is the layer, row, and column. For a grid that uses the DISV input file, CELLID is the layer and CELL2D number. If the model uses the unstructured discretization (DISU) input file, CELLID is the node number for the cell. For reaches that are not connected to an underlying GWF cell, a zero should be specified for each grid dimension. For example, for a DIS grid a CELLID of 0 0 0 should be specified. Reach-aquifer flow is not calculated for unconnected reaches. The keyword NONE can be still be specified to identify unconnected reaches for backward compatibility with previous versions of MODFLOW 6 but eventually NONE will be deprecated and will cause MODFLOW 6 to terminate with an error. 
 
 block packagedata
 name rlen
@@ -417,7 +418,7 @@ tagged false
 in_record true
 reader urword
 longname streambed thickness
-description real value that defines the thickness of the reach streambed. RBTH can be any value if CELLID is `NONE'. Otherwise, RBTH must be greater than zero.
+description real value that defines the thickness of the reach streambed. RBTH can be any value if the reach is not connected to an underlying GWF cell. Otherwise, RBTH must be greater than zero.
 
 block packagedata
 name rhk
@@ -427,7 +428,7 @@ tagged false
 in_record true
 reader urword
 longname
-description real value that defines the hydraulic conductivity of the reach streambed. RHK can be any positive value if CELLID is `NONE'. Otherwise, RHK must be greater than zero.
+description real value that defines the hydraulic conductivity of the reach streambed. RHK can be any positive value if the reach is not connected to an underlying GWF cell. Otherwise, RHK must be greater than zero.
 
 block packagedata
 name man
@@ -448,7 +449,7 @@ tagged false
 in_record true
 reader urword
 longname number of connected reaches
-description integer value that defines the number of reaches connected to the reach.  If a value of zero is specified for NCON an entry for RNO is still required in the subsequent CONNECTIONDATA block.
+description integer value that defines the number of reaches connected to the reach.  If a value of zero is specified for NCON an entry for IFNO is still required in the subsequent CONNECTIONDATA block.
 
 block packagedata
 name ustrf
@@ -498,7 +499,7 @@ description REPLACE boundname {'{#1}': 'stream reach'}
 
 block crosssections
 name crosssections
-type recarray rno tab6 filein tab6_filename
+type recarray ifno tab6 filein tab6_filename
 shape
 valid
 optional false
@@ -507,14 +508,14 @@ longname
 description
 
 block crosssections
-name rno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname reach number for this entry
-description integer value that defines the reach number associated with the specified cross-section table file on the line. RNO must be greater than zero and less than or equal to NREACHES. The program will also terminate with an error if table information for a reach is specified more than once.
+description integer value that defines the feature (reach) number associated with the specified cross-section table file on the line. IFNO must be greater than zero and less than or equal to NREACHES. The program will also terminate with an error if table information for a reach is specified more than once.
 numeric_index true
 
 block crosssections
@@ -554,27 +555,27 @@ description character string that defines the path and filename for the file con
 
 block connectiondata
 name connectiondata
-type recarray rno ic
+type recarray ifno ic
 shape (maxbound)
 reader urword
 longname
 description
 
 block connectiondata
-name rno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname reach number for this entry
-description integer value that defines the reach number associated with the specified CONNECTIONDATA data on the line. RNO must be greater than zero and less than or equal to NREACHES. Reach connection information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if connection information for a reach is specified more than once.
+description integer value that defines the feature (reach) number associated with the specified CONNECTIONDATA data on the line. IFNO must be greater than zero and less than or equal to NREACHES. Reach connection information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if connection information for a reach is specified more than once.
 numeric_index true
 
 block connectiondata
 name ic
 type integer
-shape (ncon(rno))
+shape (ncon(ifno))
 tagged false
 in_record true
 reader urword
@@ -590,21 +591,21 @@ support_negative_index true
 
 block diversions
 name diversions
-type recarray rno idv iconr cprior
+type recarray ifno idv iconr cprior
 shape (maxbound)
 reader urword
 longname
 description
 
 block diversions
-name rno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname reach number for this entry
-description integer value that defines the reach number associated with the specified DIVERSIONS data on the line. RNO must be greater than zero and less than or equal to NREACHES.  Reach diversion information must be specified for every reach with a NDV value greater than 0 or the program will terminate with an error.  The program will also terminate with an error if diversion information for a given reach diversion is specified more than once.
+description integer value that defines the feature (reach) number associated with the specified DIVERSIONS data on the line. IFNO must be greater than zero and less than or equal to NREACHES.  Reach diversion information must be specified for every reach with a NDV value greater than 0 or the program will terminate with an error.  The program will also terminate with an error if diversion information for a given reach diversion is specified more than once.
 numeric_index true
 
 block diversions
@@ -615,7 +616,7 @@ tagged false
 in_record true
 reader urword
 longname downstream diversion number
-description integer value that defines the downstream diversion number for the diversion for reach RNO. IDV must be greater than zero and less than or equal to NDV for reach RNO.
+description integer value that defines the downstream diversion number for the diversion for reach IFNO. IDV must be greater than zero and less than or equal to NDV for reach IFNO.
 numeric_index true
 
 block diversions
@@ -626,7 +627,7 @@ tagged false
 in_record true
 reader urword
 longname downstream reach number for diversion
-description integer value that defines the downstream reach that will receive the diverted water. IDV must be greater than zero and less than or equal to NREACHES. Furthermore, reach  ICONR must be a downstream connection for reach RNO.
+description integer value that defines the downstream reach that will receive the diverted water. IDV must be greater than zero and less than or equal to NREACHES. Furthermore, reach  ICONR must be a downstream connection for reach IFNO.
 numeric_index true
 
 block diversions
@@ -637,7 +638,7 @@ tagged false
 in_record true
 reader urword
 longname iprior code
-description character string value that defines the the prioritization system for the diversion, such as when insufficient water is available to meet all diversion stipulations, and is used in conjunction with the value of FLOW value specified in the STRESS\_PERIOD\_DATA section. Available diversion options include:  (1) CPRIOR = `FRACTION', then the amount of the diversion is computed as a fraction of the streamflow leaving reach RNO ($Q_{DS}$); in this case, 0.0 $\le$ DIVFLOW $\le$ 1.0.  (2) CPRIOR = `EXCESS', a diversion is made only if $Q_{DS}$ for reach RNO exceeds the value of DIVFLOW. If this occurs, then the quantity of water diverted is the excess flow ($Q_{DS} -$ DIVFLOW) and $Q_{DS}$ from reach RNO is set equal to DIVFLOW. This represents a flood-control type of diversion, as described by Danskin and Hanson (2002). (3) CPRIOR = `THRESHOLD', then if $Q_{DS}$ in reach RNO is less than the specified diversion flow DIVFLOW, no water is diverted from reach RNO. If $Q_{DS}$ in reach RNO is greater than or equal to DIVFLOW, DIVFLOW is diverted and $Q_{DS}$ is set to the remainder ($Q_{DS} -$ DIVFLOW)). This approach assumes that once flow in the stream is sufficiently low, diversions from the stream cease, and is the `priority' algorithm that originally was programmed into the STR1 Package (Prudic, 1989).  (4) CPRIOR = `UPTO' -- if $Q_{DS}$ in reach RNO is greater than or equal to the specified diversion flow DIVFLOW, $Q_{DS}$ is reduced by DIVFLOW. If $Q_{DS}$ in reach RNO is less than DIVFLOW, DIVFLOW is set to $Q_{DS}$ and there will be no flow available for reaches connected to downstream end of reach RNO.
+description character string value that defines the the prioritization system for the diversion, such as when insufficient water is available to meet all diversion stipulations, and is used in conjunction with the value of FLOW value specified in the STRESS\_PERIOD\_DATA section. Available diversion options include:  (1) CPRIOR = `FRACTION', then the amount of the diversion is computed as a fraction of the streamflow leaving reach IFNO ($Q_{DS}$); in this case, 0.0 $\le$ DIVFLOW $\le$ 1.0.  (2) CPRIOR = `EXCESS', a diversion is made only if $Q_{DS}$ for reach IFNO exceeds the value of DIVFLOW. If this occurs, then the quantity of water diverted is the excess flow ($Q_{DS} -$ DIVFLOW) and $Q_{DS}$ from reach IFNO is set equal to DIVFLOW. This represents a flood-control type of diversion, as described by Danskin and Hanson (2002). (3) CPRIOR = `THRESHOLD', then if $Q_{DS}$ in reach IFNO is less than the specified diversion flow DIVFLOW, no water is diverted from reach IFNO. If $Q_{DS}$ in reach IFNO is greater than or equal to DIVFLOW, DIVFLOW is diverted and $Q_{DS}$ is set to the remainder ($Q_{DS} -$ DIVFLOW)). This approach assumes that once flow in the stream is sufficiently low, diversions from the stream cease, and is the `priority' algorithm that originally was programmed into the STR1 Package (Prudic, 1989).  (4) CPRIOR = `UPTO' -- if $Q_{DS}$ in reach IFNO is greater than or equal to the specified diversion flow DIVFLOW, $Q_{DS}$ is reduced by DIVFLOW. If $Q_{DS}$ in reach IFNO is less than DIVFLOW, DIVFLOW is set to $Q_{DS}$ and there will be no flow available for reaches connected to downstream end of reach IFNO.
 
 
 # --------------------- gwf sfr period ---------------------
@@ -657,21 +658,21 @@ description REPLACE iper {}
 
 block period
 name perioddata
-type recarray rno sfrsetting
+type recarray ifno sfrsetting
 shape
 reader urword
 longname
 description
 
 block period
-name rno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname reach number for this entry
-description integer value that defines the reach number associated with the specified PERIOD data on the line. RNO must be greater than zero and less than or equal to NREACHES.
+description integer value that defines the feature (reach) number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NREACHES.
 numeric_index true
 
 block period
@@ -787,7 +788,7 @@ tagged false
 in_record true
 reader urword
 longname diversion number
-description an integer value specifying which diversion of reach RNO that DIVFLOW is being specified for.  Must be less or equal to ndv for the current reach (RNO).
+description an integer value specifying which diversion of reach IFNO that DIVFLOW is being specified for.  Must be less or equal to ndv for the current reach (IFNO).
 numeric_index true
 
 block period
diff --git a/doc/mf6io/mf6ivar/dfn/gwf-uzf.dfn b/doc/mf6io/mf6ivar/dfn/gwf-uzf.dfn
index 02833c08967..fdf5078eba5 100644
--- a/doc/mf6io/mf6ivar/dfn/gwf-uzf.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwf-uzf.dfn
@@ -1,5 +1,6 @@
 # --------------------- gwf uzf options ---------------------
 # flopy multi-package
+# package-type advanced-stress-package
 
 block options
 name auxiliary
@@ -365,21 +366,21 @@ default_value 40
 
 block packagedata
 name packagedata
-type recarray iuzno cellid landflag ivertcon surfdep vks thtr thts thti eps boundname
+type recarray ifno cellid landflag ivertcon surfdep vks thtr thts thti eps boundname
 shape (nuzfcells)
 reader urword
 longname
 description
 
 block packagedata
-name iuzno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname uzf id number for this entry
-description integer value that defines the UZF cell number associated with the specified PACKAGEDATA data on the line. IUZNO must be greater than zero and less than or equal to NUZFCELLS.  UZF information must be specified for every UZF cell or the program will terminate with an error.  The program will also terminate with an error if information for a UZF cell is specified more than once.
+description integer value that defines the feature (UZF object) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NUZFCELLS.  UZF information must be specified for every UZF cell or the program will terminate with an error.  The program will also terminate with an error if information for a UZF cell is specified more than once.
 numeric_index true
 
 block packagedata
@@ -502,21 +503,21 @@ description REPLACE iper {}
 
 block period
 name perioddata
-type recarray iuzno finf pet extdp extwc ha hroot rootact aux
+type recarray ifno finf pet extdp extwc ha hroot rootact aux
 shape
 reader urword
 longname
 description
 
 block period
-name iuzno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname UZF id number
-description integer value that defines the UZF cell number associated with the specified PERIOD data on the line.
+description integer value that defines the feature (UZF object) number associated with the specified PERIOD data on the line.
 numeric_index true
 
 block period
diff --git a/doc/mf6io/mf6ivar/dfn/gwf-wel.dfn b/doc/mf6io/mf6ivar/dfn/gwf-wel.dfn
index 4f7710ac5dd..c7de3e7e96f 100644
--- a/doc/mf6io/mf6ivar/dfn/gwf-wel.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwf-wel.dfn
@@ -1,5 +1,6 @@
 # --------------------- gwf wel options ---------------------
 # flopy multi-package
+# package-type stress-package
 
 block options
 name auxiliary
@@ -35,6 +36,7 @@ reader urword
 optional true
 longname print input to listing file
 description REPLACE print_input {'{#1}': 'well'}
+mf6internal iprpak
 
 block options
 name print_flows
@@ -43,6 +45,7 @@ reader urword
 optional true
 longname print calculated flows to listing file
 description REPLACE print_flows {'{#1}': 'well'}
+mf6internal iprflow
 
 block options
 name save_flows
@@ -51,6 +54,7 @@ reader urword
 optional true
 longname save well flows to budget file
 description REPLACE save_flows {'{#1}': 'well'}
+mf6internal ipakcb
 
 block options
 name auto_flow_reduce
@@ -59,6 +63,7 @@ reader urword
 optional true
 longname cell fractional thickness for reduced pumping
 description keyword and real value that defines the fraction of the cell thickness used as an interval for smoothly adjusting negative pumping rates to 0 in cells with head values less than or equal to the bottom of the cell. Negative pumping rates are adjusted to 0 or a smaller negative value when the head in the cell is equal to or less than the calculated interval above the cell bottom. AUTO\_FLOW\_REDUCE is set to 0.1 if the specified value is less than or equal to zero. By default, negative pumping rates are not reduced during a simulation.
+mf6internal flowred
 
 block options
 name afrcsv_filerecord
@@ -69,6 +74,7 @@ tagged true
 optional true
 longname
 description
+mf6internal afrcsv_rec
 
 block options
 name auto_flow_reduce_csv
@@ -80,6 +86,7 @@ tagged true
 optional false
 longname budget keyword
 description keyword to specify that record corresponds to the AUTO\_FLOW\_REDUCE output option in which a new record is written for each well and for each time step in which the user-requested extraction rate is reduced by the program.
+mf6internal afrcsv
 
 block options
 name fileout
@@ -221,6 +228,7 @@ shape (maxbound)
 reader urword
 longname
 description
+mf6internal spd
 
 block period
 name cellid
@@ -254,6 +262,7 @@ optional true
 time_series true
 longname auxiliary variables
 description REPLACE aux {'{#1}': 'well'}
+mf6internal auxvar
 
 block period
 name boundname
diff --git a/doc/mf6io/mf6ivar/dfn/gwt-cnc.dfn b/doc/mf6io/mf6ivar/dfn/gwt-cnc.dfn
index e3ef02bce6c..3a75ccb4cf7 100644
--- a/doc/mf6io/mf6ivar/dfn/gwt-cnc.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwt-cnc.dfn
@@ -1,4 +1,5 @@
 # --------------------- gwt cnc options ---------------------
+# flopy multi-package
 
 block options
 name auxiliary
@@ -34,6 +35,7 @@ reader urword
 optional true
 longname print input to listing file
 description REPLACE print_input {'{#1}': 'constant concentration'}
+mf6internal iprflow
 
 block options
 name print_flows
@@ -42,6 +44,7 @@ reader urword
 optional true
 longname print calculated flows to listing file
 description REPLACE print_flows {'{#1}': 'constant concentration'}
+mf6internal ipakcb
 
 block options
 name save_flows
@@ -50,6 +53,7 @@ reader urword
 optional true
 longname save constant concentration flows to budget file
 description REPLACE save_flows {'{#1}': 'constant concentration'}
+mf6internal iprpak
 
 block options
 name ts_filerecord
@@ -160,6 +164,7 @@ shape (maxbound)
 reader urword
 longname
 description
+mf6internal spd
 
 block period
 name cellid
@@ -181,6 +186,7 @@ reader urword
 time_series true
 longname constant concentration value
 description is the constant concentration value. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value.
+mf6internal tspvar
 
 block period
 name aux
@@ -193,6 +199,7 @@ optional true
 time_series true
 longname auxiliary variables
 description REPLACE aux {'{#1}': 'constant concentration'}
+mf6internal auxvar
 
 block period
 name boundname
diff --git a/doc/mf6io/mf6ivar/dfn/gwt-disu.dfn b/doc/mf6io/mf6ivar/dfn/gwt-disu.dfn
index 09043e92ca5..00ffe21ad09 100644
--- a/doc/mf6io/mf6ivar/dfn/gwt-disu.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwt-disu.dfn
@@ -176,7 +176,7 @@ name vertices
 type recarray iv xv yv
 shape (nvert)
 reader urword
-optional false
+optional true
 longname vertices data
 description
 
@@ -219,7 +219,7 @@ name cell2d
 type recarray icell2d xc yc ncvert icvert
 shape (nodes)
 reader urword
-optional false
+optional true
 longname cell2d data
 description
 
diff --git a/doc/mf6io/mf6ivar/dfn/gwt-lkt.dfn b/doc/mf6io/mf6ivar/dfn/gwt-lkt.dfn
index 44fb4422ca6..6dbca6ffb12 100644
--- a/doc/mf6io/mf6ivar/dfn/gwt-lkt.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwt-lkt.dfn
@@ -259,21 +259,21 @@ description REPLACE obs6_filename {'{#1}': 'LKT'}
 
 block packagedata
 name packagedata
-type recarray lakeno strt aux boundname
+type recarray ifno strt aux boundname
 shape (maxbound)
 reader urword
 longname
 description
 
 block packagedata
-name lakeno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname lake number for this entry
-description integer value that defines the lake number associated with the specified PACKAGEDATA data on the line. LAKENO must be greater than zero and less than or equal to NLAKES. Lake information must be specified for every lake or the program will terminate with an error.  The program will also terminate with an error if information for a lake is specified more than once.
+description integer value that defines the feature (lake) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NLAKES. Lake information must be specified for every lake or the program will terminate with an error.  The program will also terminate with an error if information for a lake is specified more than once.
 numeric_index true
 
 block packagedata
@@ -327,21 +327,21 @@ description REPLACE iper {}
 
 block period
 name lakeperioddata
-type recarray lakeno laksetting
+type recarray ifno laksetting
 shape
 reader urword
 longname
 description
 
 block period
-name lakeno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname lake number for this entry
-description integer value that defines the lake number associated with the specified PERIOD data on the line. LAKENO must be greater than zero and less than or equal to NLAKES.
+description integer value that defines the feature (lake) number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NLAKES.
 numeric_index true
 
 block period
@@ -352,7 +352,7 @@ tagged false
 in_record true
 reader urword
 longname
-description line of information that is parsed into a keyword and values.  Keyword values that can be used to start the LAKSETTING string include: STATUS, CONCENTRATION, RAINFALL, EVAPORATION, RUNOFF, and AUXILIARY.  These settings are used to assign the concentration of associated with the corresponding flow terms.  Concentrations cannot be specified for all flow terms.  For example, the Lake Package supports a ``WITHDRAWAL'' flow term.  If this withdrawal term is active, then water will be withdrawn from the lake at the calculated concentration of the lake.
+description line of information that is parsed into a keyword and values.  Keyword values that can be used to start the LAKSETTING string include: STATUS, CONCENTRATION, RAINFALL, EVAPORATION, RUNOFF, EXT-INFLOW, and AUXILIARY.  These settings are used to assign the concentration of associated with the corresponding flow terms.  Concentrations cannot be specified for all flow terms.  For example, the Lake Package supports a ``WITHDRAWAL'' flow term.  If this withdrawal term is active, then water will be withdrawn from the lake at the calculated concentration of the lake.
 
 block period
 name status
diff --git a/doc/mf6io/mf6ivar/dfn/gwt-mwt.dfn b/doc/mf6io/mf6ivar/dfn/gwt-mwt.dfn
index 67529c4b8a9..b2b43467858 100644
--- a/doc/mf6io/mf6ivar/dfn/gwt-mwt.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwt-mwt.dfn
@@ -259,21 +259,21 @@ description REPLACE obs6_filename {'{#1}': 'MWT'}
 
 block packagedata
 name packagedata
-type recarray mawno strt aux boundname
+type recarray ifno strt aux boundname
 shape (maxbound)
 reader urword
 longname
 description
 
 block packagedata
-name mawno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname well number for this entry
-description integer value that defines the well number associated with the specified PACKAGEDATA data on the line. MAWNO must be greater than zero and less than or equal to NMAWWELLS. Well information must be specified for every well or the program will terminate with an error.  The program will also terminate with an error if information for a well is specified more than once.
+description integer value that defines the feature (well) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NMAWWELLS. Well information must be specified for every well or the program will terminate with an error.  The program will also terminate with an error if information for a well is specified more than once.
 numeric_index true
 
 block packagedata
@@ -327,21 +327,21 @@ description REPLACE iper {}
 
 block period
 name mwtperioddata
-type recarray mawno mwtsetting
+type recarray ifno mwtsetting
 shape
 reader urword
 longname
 description
 
 block period
-name mawno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname well number for this entry
-description integer value that defines the well number associated with the specified PERIOD data on the line. MAWNO must be greater than zero and less than or equal to NMAWWELLS.
+description integer value that defines the feature (well) number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NMAWWELLS.
 numeric_index true
 
 block period
@@ -352,7 +352,7 @@ tagged false
 in_record true
 reader urword
 longname
-description line of information that is parsed into a keyword and values.  Keyword values that can be used to start the MWTSETTING string include: STATUS, CONCENTRATION, RAINFALL, EVAPORATION, RUNOFF, and AUXILIARY.  These settings are used to assign the concentration associated with the corresponding flow terms.  Concentrations cannot be specified for all flow terms.  For example, the Multi-Aquifer Well Package supports a ``WITHDRAWAL'' flow term.  If this withdrawal term is active, then water will be withdrawn from the well at the calculated concentration of the well.
+description line of information that is parsed into a keyword and values.  Keyword values that can be used to start the MWTSETTING string include: STATUS, CONCENTRATION, RATE, and AUXILIARY.  These settings are used to assign the concentration associated with the corresponding flow terms.  Concentrations cannot be specified for all flow terms.  For example, the Multi-Aquifer Well Package supports a ``WITHDRAWAL'' flow term.  If this withdrawal term is active, then water will be withdrawn from the well at the calculated concentration of the well.
 
 block period
 name status
diff --git a/doc/mf6io/mf6ivar/dfn/gwt-sft.dfn b/doc/mf6io/mf6ivar/dfn/gwt-sft.dfn
index dc98b6a2bed..5323f4c7c5e 100644
--- a/doc/mf6io/mf6ivar/dfn/gwt-sft.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwt-sft.dfn
@@ -259,21 +259,21 @@ description REPLACE obs6_filename {'{#1}': 'SFT'}
 
 block packagedata
 name packagedata
-type recarray rno strt aux boundname
+type recarray ifno strt aux boundname
 shape (maxbound)
 reader urword
 longname
 description
 
 block packagedata
-name rno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname reach number for this entry
-description integer value that defines the reach number associated with the specified PACKAGEDATA data on the line. RNO must be greater than zero and less than or equal to NREACHES. Reach information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if information for a reach is specified more than once.
+description integer value that defines the feature (reach) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NREACHES. Reach information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if information for a reach is specified more than once.
 numeric_index true
 
 block packagedata
@@ -327,21 +327,21 @@ description REPLACE iper {}
 
 block period
 name reachperioddata
-type recarray rno reachsetting
+type recarray ifno reachsetting
 shape
 reader urword
 longname
 description
 
 block period
-name rno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname reach number for this entry
-description integer value that defines the reach number associated with the specified PERIOD data on the line. RNO must be greater than zero and less than or equal to NREACHES.
+description integer value that defines the feature (reach) number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NREACHES.
 numeric_index true
 
 block period
diff --git a/doc/mf6io/mf6ivar/dfn/gwt-uzt.dfn b/doc/mf6io/mf6ivar/dfn/gwt-uzt.dfn
index d95baabe6e4..00524848bdd 100644
--- a/doc/mf6io/mf6ivar/dfn/gwt-uzt.dfn
+++ b/doc/mf6io/mf6ivar/dfn/gwt-uzt.dfn
@@ -259,21 +259,21 @@ description REPLACE obs6_filename {'{#1}': 'UZT'}
 
 block packagedata
 name packagedata
-type recarray uzfno strt aux boundname
+type recarray ifno strt aux boundname
 shape (maxbound)
 reader urword
 longname
 description
 
 block packagedata
-name uzfno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname UZF cell number for this entry
-description integer value that defines the UZF cell number associated with the specified PACKAGEDATA data on the line. UZFNO must be greater than zero and less than or equal to NUZFCELLS. Unsaturated zone flow information must be specified for every UZF cell or the program will terminate with an error.  The program will also terminate with an error if information for a UZF cell is specified more than once.
+description integer value that defines the feature (UZF object) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NUZFCELLS. Unsaturated zone flow information must be specified for every UZF cell or the program will terminate with an error.  The program will also terminate with an error if information for a UZF cell is specified more than once.
 numeric_index true
 
 block packagedata
@@ -327,21 +327,21 @@ description REPLACE iper {}
 
 block period
 name uztperioddata
-type recarray uzfno uztsetting
+type recarray ifno uztsetting
 shape
 reader urword
 longname
 description
 
 block period
-name uzfno
+name ifno
 type integer
 shape
 tagged false
 in_record true
 reader urword
 longname unsaturated zone flow cell number for this entry
-description integer value that defines the UZF cell number associated with the specified PERIOD data on the line. UZFNO must be greater than zero and less than or equal to NUZFCELLS.
+description integer value that defines the feature (UZF object) number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NUZFCELLS.
 numeric_index true
 
 block period
diff --git a/doc/mf6io/mf6ivar/dfn/utl-spc.dfn b/doc/mf6io/mf6ivar/dfn/utl-spc.dfn
index 5ca5bd0ae00..6fabd0c0f6a 100644
--- a/doc/mf6io/mf6ivar/dfn/utl-spc.dfn
+++ b/doc/mf6io/mf6ivar/dfn/utl-spc.dfn
@@ -104,7 +104,7 @@ tagged false
 in_record true
 reader urword
 longname
-description line of information that is parsed into a keyword and values.  Keyword values that can be used to start the MAWSETTING string include: CONCENTRATION.
+description line of information that is parsed into a keyword and values.  Keyword values that can be used to start the SPCSETTING string include: CONCENTRATION.
 
 block period
 name concentration
diff --git a/doc/mf6io/mf6ivar/examples/gwf-lak-example.dat b/doc/mf6io/mf6ivar/examples/gwf-lak-example.dat
index 9e3250aa2c2..b422457ba66 100644
--- a/doc/mf6io/mf6ivar/examples/gwf-lak-example.dat
+++ b/doc/mf6io/mf6ivar/examples/gwf-lak-example.dat
@@ -13,69 +13,69 @@ BEGIN DIMENSIONS
 END DIMENSIONS
 
 BEGIN PACKAGEDATA
-# lakeno    strt lakeconn  boundname
-       1  110.00       57  LAKE_1
+# ifno    strt lakeconn  boundname
+     1  110.00       57  LAKE_1
 END PACKAGEDATA
 
 BEGIN CONNECTIONDATA
-# lakeno iconn layer row column       ctype bedleak belev telev  dx width
-       1     1     1   7      6  HORIZONTAL     0.1     0     0 500   500
-       1     2     1   8      6  HORIZONTAL     0.1     0     0 500   500
-       1     3     1   9      6  HORIZONTAL     0.1     0     0 500   500
-       1     4     1  10      6  HORIZONTAL     0.1     0     0 500   500
-       1     5     1  11      6  HORIZONTAL     0.1     0     0 500   500
-       1     6     1   6      7  HORIZONTAL     0.1     0     0 500   500
-       1     7     2   7      7    VERTICAL     0.1     0     0   0     0
-       1     8     2   8      7    VERTICAL     0.1     0     0   0     0
-       1     9     2   8      7  HORIZONTAL     0.1     0     0 250   500
-       1    10     2   9      7    VERTICAL     0.1     0     0   0     0
-       1    11     2   9      7  HORIZONTAL     0.1     0     0 250   500
-       1    12     2  10      7    VERTICAL     0.1     0     0   0     0
-       1    13     2  10      7  HORIZONTAL     0.1     0     0 250   500
-       1    14     2  11      7    VERTICAL     0.1     0     0   0     0
-       1    15     1  12      7  HORIZONTAL     0.1     0     0 500   500
-       1    16     1   6      8  HORIZONTAL     0.1     0     0 500   500
-       1    17     2   7      8    VERTICAL     0.1     0     0   0     0
-       1    18     2   7      8  HORIZONTAL     0.1     0     0 250   500
-       1    19     3   8      8    VERTICAL     0.1     0     0   0     0
-       1    20     3   9      8    VERTICAL     0.1     0     0   0     0
-       1    21     3  10      8    VERTICAL     0.1     0     0   0     0
-       1    22     2  11      8    VERTICAL     0.1     0     0   0     0
-       1    23     2  11      8  HORIZONTAL     0.1     0     0 250   500
-       1    24     1  12      8  HORIZONTAL     0.1     0     0 500   500
-       1    25     1   6      9  HORIZONTAL     0.1     0     0 500   500
-       1    26     2   7      9    VERTICAL     0.1     0     0   0     0
-       1    27     2   7      9  HORIZONTAL     0.1     0     0 250   500
-       1    28     3   8      9    VERTICAL     0.1     0     0   0     0
-       1    29     3   9      9    VERTICAL     0.1     0     0   0     0
-       1    30     3  10      9    VERTICAL     0.1     0     0   0     0
-       1    31     2  11      9    VERTICAL     0.1     0     0   0     0
-       1    32     2  11      9  HORIZONTAL     0.1     0     0 250   500
-       1    33     1  12      9  HORIZONTAL     0.1     0     0 500   500
-       1    34     1   6     10  HORIZONTAL     0.1     0     0 500   500
-       1    35     2   7     10    VERTICAL     0.1     0     0   0     0
-       1    36     2   7     10  HORIZONTAL     0.1     0     0 250   500
-       1    37     3   8     10    VERTICAL     0.1     0     0   0     0
-       1    38     3   9     10    VERTICAL     0.1     0     0   0     0
-       1    39     3  10     10    VERTICAL     0.1     0     0   0     0
-       1    40     2  11     10    VERTICAL     0.1     0     0   0     0
-       1    41     2  11     10  HORIZONTAL     0.1     0     0 250   500
-       1    42     1  12     10  HORIZONTAL     0.1     0     0 500   500
-       1    43     1   6     11  HORIZONTAL     0.1     0     0 500   500
-       1    44     2   7     11    VERTICAL     0.1     0     0   0     0
-       1    45     2   8     11    VERTICAL     0.1     0     0   0     0
-       1    46     2   8     11  HORIZONTAL     0.1     0     0 250   500
-       1    47     2   9     11    VERTICAL     0.1     0     0   0     0
-       1    48     2   9     11  HORIZONTAL     0.1     0     0 250   500
-       1    49     2  10     11    VERTICAL     0.1     0     0   0     0
-       1    50     2  10     11  HORIZONTAL     0.1     0     0 250   500
-       1    51     2  11     11    VERTICAL     0.1     0     0   0     0
-       1    52     1  12     11  HORIZONTAL     0.1     0     0 500   500
-       1    53     1   7     12  HORIZONTAL     0.1     0     0 500   500
-       1    54     1   8     12  HORIZONTAL     0.1     0     0 500   500
-       1    55     1   9     12  HORIZONTAL     0.1     0     0 500   500
-       1    56     1  10     12  HORIZONTAL     0.1     0     0 500   500
-       1    57     1  11     12  HORIZONTAL     0.1     0     0 500   500
+# ifno iconn layer row column       ctype bedleak belev telev  dx width
+     1     1     1   7      6  HORIZONTAL     0.1     0     0 500   500
+     1     2     1   8      6  HORIZONTAL     0.1     0     0 500   500
+     1     3     1   9      6  HORIZONTAL     0.1     0     0 500   500
+     1     4     1  10      6  HORIZONTAL     0.1     0     0 500   500
+     1     5     1  11      6  HORIZONTAL     0.1     0     0 500   500
+     1     6     1   6      7  HORIZONTAL     0.1     0     0 500   500
+     1     7     2   7      7    VERTICAL     0.1     0     0   0     0
+     1     8     2   8      7    VERTICAL     0.1     0     0   0     0
+     1     9     2   8      7  HORIZONTAL     0.1     0     0 250   500
+     1    10     2   9      7    VERTICAL     0.1     0     0   0     0
+     1    11     2   9      7  HORIZONTAL     0.1     0     0 250   500
+     1    12     2  10      7    VERTICAL     0.1     0     0   0     0
+     1    13     2  10      7  HORIZONTAL     0.1     0     0 250   500
+     1    14     2  11      7    VERTICAL     0.1     0     0   0     0
+     1    15     1  12      7  HORIZONTAL     0.1     0     0 500   500
+     1    16     1   6      8  HORIZONTAL     0.1     0     0 500   500
+     1    17     2   7      8    VERTICAL     0.1     0     0   0     0
+     1    18     2   7      8  HORIZONTAL     0.1     0     0 250   500
+     1    19     3   8      8    VERTICAL     0.1     0     0   0     0
+     1    20     3   9      8    VERTICAL     0.1     0     0   0     0
+     1    21     3  10      8    VERTICAL     0.1     0     0   0     0
+     1    22     2  11      8    VERTICAL     0.1     0     0   0     0
+     1    23     2  11      8  HORIZONTAL     0.1     0     0 250   500
+     1    24     1  12      8  HORIZONTAL     0.1     0     0 500   500
+     1    25     1   6      9  HORIZONTAL     0.1     0     0 500   500
+     1    26     2   7      9    VERTICAL     0.1     0     0   0     0
+     1    27     2   7      9  HORIZONTAL     0.1     0     0 250   500
+     1    28     3   8      9    VERTICAL     0.1     0     0   0     0
+     1    29     3   9      9    VERTICAL     0.1     0     0   0     0
+     1    30     3  10      9    VERTICAL     0.1     0     0   0     0
+     1    31     2  11      9    VERTICAL     0.1     0     0   0     0
+     1    32     2  11      9  HORIZONTAL     0.1     0     0 250   500
+     1    33     1  12      9  HORIZONTAL     0.1     0     0 500   500
+     1    34     1   6     10  HORIZONTAL     0.1     0     0 500   500
+     1    35     2   7     10    VERTICAL     0.1     0     0   0     0
+     1    36     2   7     10  HORIZONTAL     0.1     0     0 250   500
+     1    37     3   8     10    VERTICAL     0.1     0     0   0     0
+     1    38     3   9     10    VERTICAL     0.1     0     0   0     0
+     1    39     3  10     10    VERTICAL     0.1     0     0   0     0
+     1    40     2  11     10    VERTICAL     0.1     0     0   0     0
+     1    41     2  11     10  HORIZONTAL     0.1     0     0 250   500
+     1    42     1  12     10  HORIZONTAL     0.1     0     0 500   500
+     1    43     1   6     11  HORIZONTAL     0.1     0     0 500   500
+     1    44     2   7     11    VERTICAL     0.1     0     0   0     0
+     1    45     2   8     11    VERTICAL     0.1     0     0   0     0
+     1    46     2   8     11  HORIZONTAL     0.1     0     0 250   500
+     1    47     2   9     11    VERTICAL     0.1     0     0   0     0
+     1    48     2   9     11  HORIZONTAL     0.1     0     0 250   500
+     1    49     2  10     11    VERTICAL     0.1     0     0   0     0
+     1    50     2  10     11  HORIZONTAL     0.1     0     0 250   500
+     1    51     2  11     11    VERTICAL     0.1     0     0   0     0
+     1    52     1  12     11  HORIZONTAL     0.1     0     0 500   500
+     1    53     1   7     12  HORIZONTAL     0.1     0     0 500   500
+     1    54     1   8     12  HORIZONTAL     0.1     0     0 500   500
+     1    55     1   9     12  HORIZONTAL     0.1     0     0 500   500
+     1    56     1  10     12  HORIZONTAL     0.1     0     0 500   500
+     1    57     1  11     12  HORIZONTAL     0.1     0     0 500   500
 END CONNECTIONDATA
 
 BEGIN OUTLETS
diff --git a/doc/mf6io/mf6ivar/examples/gwf-maw-example1.dat b/doc/mf6io/mf6ivar/examples/gwf-maw-example1.dat
index d0cd90b41ae..416a69593f0 100644
--- a/doc/mf6io/mf6ivar/examples/gwf-maw-example1.dat
+++ b/doc/mf6io/mf6ivar/examples/gwf-maw-example1.dat
@@ -12,16 +12,16 @@ begin dimensions
 end dimensions
 
 begin packagedata
-#  wellno radius bottom strt condeqn ngwnodes name          
-        1   0.15 -100.0 9.14   thiem        2 pwell
-        2   0.25 -100.0 9.14   thiem        1 iwell
+# ifno radius bottom strt condeqn ngwnodes name          
+     1   0.15 -100.0 9.14   thiem        2 pwell
+     2   0.25 -100.0 9.14   thiem        1 iwell
 end packagedata
 
 begin connectiondata
-# wellno conn l  r  c  stop sbot  k  rskin
-       1    1 1 51 51     0    0  0      0
-       1    2 2 51 51     0    0  0      0
-       2    1 2  2  2     0    0  0      0
+# ifno conn l  r  c  stop sbot  k  rskin
+     1    1 1 51 51     0    0  0      0
+     1    2 2 51 51     0    0  0      0
+     2    1 2  2  2     0    0  0      0
 end connectiondata
 
 begin period 1
diff --git a/doc/mf6io/mf6ivar/examples/gwf-maw-example2.dat b/doc/mf6io/mf6ivar/examples/gwf-maw-example2.dat
index fc9f856fe94..fe50eb04554 100644
--- a/doc/mf6io/mf6ivar/examples/gwf-maw-example2.dat
+++ b/doc/mf6io/mf6ivar/examples/gwf-maw-example2.dat
@@ -10,16 +10,16 @@ begin dimensions
 end dimensions
 
 begin packagedata
-#  wellno radius bottom strt   condeqn ngwnodes name
-        1   0.15 -100.0 9.14      mean        2 pwell
-        2   0.25 -100.0 9.14      mean        1 iwell
+#  ifno radius bottom strt   condeqn ngwnodes name
+      1   0.15 -100.0 9.14      mean        2 pwell
+      2   0.25 -100.0 9.14      mean        1 iwell
 end packagedata
 
 begin connectiondata
-# wellno conn l  r  c  stop  sbot  k  rskin
-       1    1 1 51 51    0. -100. 361.  .25
-       1    2 2 51 51    0. -100. 361.  .25
-       2    1 2  2  2  -50. -100. 361   .50
+# ifno conn l  r  c  stop  sbot  k  rskin
+     1    1 1 51 51    0. -100. 361.  .25
+     1    2 2 51 51    0. -100. 361.  .25
+     2    1 2  2  2  -50. -100. 361   .50
 end connectiondata
 
 begin period 1
diff --git a/doc/mf6io/mf6ivar/examples/gwf-maw-example3.dat b/doc/mf6io/mf6ivar/examples/gwf-maw-example3.dat
index a8742eba367..f0477598e97 100644
--- a/doc/mf6io/mf6ivar/examples/gwf-maw-example3.dat
+++ b/doc/mf6io/mf6ivar/examples/gwf-maw-example3.dat
@@ -11,14 +11,14 @@ begin dimensions
 end dimensions
 
 begin packagedata
-#  wellno radius bottom strt   condeqn ngwnodes name
-        1   0.15 -514.9 9.14 specified        2 ntwell
+# ifno radius bottom strt   condeqn ngwnodes name
+     1   0.15 -514.9 9.14 specified        2 ntwell
 end packagedata
 
 begin connectiondata
-# wellno conn l  r  c  stop   sbot         k  rskin
-       1    1 1 51 51   -50 -514.9  111.3763      0
-       1    2 2 51 51   -50 -514.9  445.9849      0
+# ifno conn l  r  c  stop   sbot         k  rskin
+     1    1 1 51 51   -50 -514.9  111.3763      0
+     1    2 2 51 51   -50 -514.9  445.9849      0
 end connectiondata
 
 begin period 1
diff --git a/doc/mf6io/mf6ivar/examples/gwf-rch-example.dat b/doc/mf6io/mf6ivar/examples/gwf-rch-example.dat
index 21086eb5ff0..c37205b5ee7 100644
--- a/doc/mf6io/mf6ivar/examples/gwf-rch-example.dat
+++ b/doc/mf6io/mf6ivar/examples/gwf-rch-example.dat
@@ -14,7 +14,6 @@ BEGIN DIMENSIONS
 END DIMENSIONS
 
 BEGIN PERIOD 1
-  RECHARGE
   # Lay  Row  Col  Rate   Var1  Var2   mult  BoundName
      1    1    1   rch_1   1.0   2.0     1.0       Rch-1-1
      1    1    2   rch_1   1.1   2.1     1.0       Rch-1-2
diff --git a/doc/mf6io/mf6ivar/examples/gwf-sfr-example.dat b/doc/mf6io/mf6ivar/examples/gwf-sfr-example.dat
index 18d885dfd4c..e91f90ee487 100644
--- a/doc/mf6io/mf6ivar/examples/gwf-sfr-example.dat
+++ b/doc/mf6io/mf6ivar/examples/gwf-sfr-example.dat
@@ -13,94 +13,94 @@ BEGIN DIMENSIONS
 END DIMENSIONS
 
 BEGIN PACKAGEDATA
-#rno k  i j rlen rwid        rgrd      rtp   rbth     rhk   man  ncon ustrf  ndv  boundname
-   1 1  1 1 4500.  12    8.67E-04 1093.048    3.0 0.00003  0.03     1   1.0    0    reach1
-   2 1  2 2 7000.  12    8.67E-04 1088.059    3.0 0.00003  0.03     2   1.0    0    reach2
-   3 1  3 3 6000.  12    8.67E-04 1082.419    3.0 0.00003  0.03     2   1.0    0    reach3
-   4 1  3 4 5550.  12    8.67E-04 1077.408    3.0 0.00003  0.03     3   1.0    1    reach4
-   5 1  4 5 6500.  12    9.43E-04 1071.934    3.0 0.00003  0.03     2   1.0    0
-   6 1  5 6 5000.  12    9.43E-04 1066.509    3.0 0.00003  0.03     2   1.0    0
-   7 1  6 6 5000.  12    9.43E-04 1061.792    3.0 0.00003  0.03     2   1.0    0
-   8 1  7 6 5000.  12    9.43E-04 1057.075    3.0 0.00003  0.03     2   1.0    0
-   9 1  8 6 5000.  12    9.43E-04 1052.359    3.0 0.00003  0.03     2   1.0    0
-  10 1  3 5 5000.  10    5.45E-04 1073.636    2.0 0.00003  0.03     2   0.0    0    canal
-  11 1  3 6 5000.  10    5.45E-04 1070.909    2.0 0.00003  0.03     2   1.0    0    canal
-  12 1  3 7 4500.  10    5.45E-04 1068.318    2.0 0.00003  0.03     2   1.0    0    canal
-  13 1  4 8 6000.  10    5.45E-04 1065.455    2.0 0.00003  0.03     2   1.0    0    canal
-  14 1  5 8 5000.  10    5.45E-04 1062.455    2.0 0.00003  0.03     2   1.0    0    canal
-  15 1  6 8 2000.  10    5.45E-04 1060.545    2.0 0.00003  0.03     2   1.0    0    canal
-  16 1  510 2500.  10    1.81E-03 1077.727    3.0 0.00003  0.03     1   1.0    0
-  17 1  5 9 5000.  10    1.81E-03 1070.909    3.0 0.00003  0.03     2   1.0    0
-  18 1  6 8 3500.  10    1.81E-03 1063.182    3.0 0.00003  0.03     2   1.0    0
-  19 1  6 8 4000.  15    1.00E-03 1058.000    3.0 0.00003  0.03     3   1.0    0
-  20 1  7 7 5000.  15    1.00E-03 1053.500    3.0 0.00003  0.03     2   1.0    0
-  21 1  8 7 3500.  15    1.00E-03 1049.250    3.0 0.00003  0.03     2   1.0    0
-  22 1  8 6 2500.  15    1.00E-03 1046.250    3.0 0.00003  0.03     2   1.0    0
-  23 1  9 6 5000.  12    9.09E-04 1042.727    3.0 0.00003  0.03     3   1.0    0
-  24 1 10 7 5000.  12    9.09E-04 1038.182    3.0 0.00003  0.03     2   1.0    0
-  25 1 11 7 5000.  12    9.09E-04 1033.636    3.0 0.00003  0.03     2   1.0    0
-  26 1 12 7 5000.  12    9.09E-04 1029.091    3.0 0.00003  0.03     2   1.0    0
-  27 1 13 7 2000.  12    9.09E-04 1025.909    3.0 0.00003  0.03     2   1.0    0
-  28 1 14 9 5000.  55    9.67E-04 1037.581    3.0 0.00006  0.025    1   1.0    0
-  29 1 13 8 5500.  55    9.67E-04 1032.500    3.0 0.00006  0.025    2   1.0    0
-  30 1 13 7 5000.  55    9.67E-04 1027.419    3.0 0.00006  0.025    2   1.0    0
-  31 1 13 6 5000.  40    1.25E-03 1021.875    3.0 0.00006  0.025    3   1.0    0
-  32 1 13 5 5000.  40    1.25E-03 1015.625    3.0 0.00006  0.025    2   1.0    0
-  33 1 13 4 5000.  40    1.25E-03 1009.375    3.0 0.00006  0.025    2   1.0    0
-  34 1 13 3 5000.  40    1.25E-03 1003.125    3.0 0.00006  0.025    2   1.0    0
-  35 1 13 2 5000.  40    1.25E-03 996.8750    3.0 0.00006  0.025    2   1.0    0
-  36 1 13 1 3000.  40    1.25E-03 991.8750    3.0 0.00006  0.025    2   1.0    0
-  37 none   5000.  40    1.25E-03 985.6250    3.0 0.00006  0.025    1   1.0    0
+#ifno k  i  j rlen rwid        rgrd      rtp   rbth     rhk   man  ncon ustrf  ndv  boundname
+    1 1  1  1 4500.  12    8.67E-04 1093.048    3.0 0.00003  0.03     1   1.0    0    reach1
+    2 1  2  2 7000.  12    8.67E-04 1088.059    3.0 0.00003  0.03     2   1.0    0    reach2
+    3 1  3  3 6000.  12    8.67E-04 1082.419    3.0 0.00003  0.03     2   1.0    0    reach3
+    4 1  3  4 5550.  12    8.67E-04 1077.408    3.0 0.00003  0.03     3   1.0    1    reach4
+    5 1  4  5 6500.  12    9.43E-04 1071.934    3.0 0.00003  0.03     2   1.0    0
+    6 1  5  6 5000.  12    9.43E-04 1066.509    3.0 0.00003  0.03     2   1.0    0
+    7 1  6  6 5000.  12    9.43E-04 1061.792    3.0 0.00003  0.03     2   1.0    0
+    8 1  7  6 5000.  12    9.43E-04 1057.075    3.0 0.00003  0.03     2   1.0    0
+    9 1  8  6 5000.  12    9.43E-04 1052.359    3.0 0.00003  0.03     2   1.0    0
+   10 1  3  5 5000.  10    5.45E-04 1073.636    2.0 0.00003  0.03     2   0.0    0    canal
+   11 1  3  6 5000.  10    5.45E-04 1070.909    2.0 0.00003  0.03     2   1.0    0    canal
+   12 1  3  7 4500.  10    5.45E-04 1068.318    2.0 0.00003  0.03     2   1.0    0    canal
+   13 1  4  8 6000.  10    5.45E-04 1065.455    2.0 0.00003  0.03     2   1.0    0    canal
+   14 1  5  8 5000.  10    5.45E-04 1062.455    2.0 0.00003  0.03     2   1.0    0    canal
+   15 1  6  8 2000.  10    5.45E-04 1060.545    2.0 0.00003  0.03     2   1.0    0    canal
+   16 1  5 10 2500.  10    1.81E-03 1077.727    3.0 0.00003  0.03     1   1.0    0
+   17 1  5  9 5000.  10    1.81E-03 1070.909    3.0 0.00003  0.03     2   1.0    0
+   18 1  6  8 3500.  10    1.81E-03 1063.182    3.0 0.00003  0.03     2   1.0    0
+   19 1  6  8 4000.  15    1.00E-03 1058.000    3.0 0.00003  0.03     3   1.0    0
+   20 1  7  7 5000.  15    1.00E-03 1053.500    3.0 0.00003  0.03     2   1.0    0
+   21 1  8  7 3500.  15    1.00E-03 1049.250    3.0 0.00003  0.03     2   1.0    0
+   22 1  8  6 2500.  15    1.00E-03 1046.250    3.0 0.00003  0.03     2   1.0    0
+   23 1  9  6 5000.  12    9.09E-04 1042.727    3.0 0.00003  0.03     3   1.0    0
+   24 1 10  7 5000.  12    9.09E-04 1038.182    3.0 0.00003  0.03     2   1.0    0
+   25 1 11  7 5000.  12    9.09E-04 1033.636    3.0 0.00003  0.03     2   1.0    0
+   26 1 12  7 5000.  12    9.09E-04 1029.091    3.0 0.00003  0.03     2   1.0    0
+   27 1 13  7 2000.  12    9.09E-04 1025.909    3.0 0.00003  0.03     2   1.0    0
+   28 1 14  9 5000.  55    9.67E-04 1037.581    3.0 0.00006  0.025    1   1.0    0
+   29 1 13  8 5500.  55    9.67E-04 1032.500    3.0 0.00006  0.025    2   1.0    0
+   30 1 13  7 5000.  55    9.67E-04 1027.419    3.0 0.00006  0.025    2   1.0    0
+   31 1 13  6 5000.  40    1.25E-03 1021.875    3.0 0.00006  0.025    3   1.0    0
+   32 1 13  5 5000.  40    1.25E-03 1015.625    3.0 0.00006  0.025    2   1.0    0
+   33 1 13  4 5000.  40    1.25E-03 1009.375    3.0 0.00006  0.025    2   1.0    0
+   34 1 13  3 5000.  40    1.25E-03 1003.125    3.0 0.00006  0.025    2   1.0    0
+   35 1 13  2 5000.  40    1.25E-03 996.8750    3.0 0.00006  0.025    2   1.0    0
+   36 1 13  1 3000.  40    1.25E-03 991.8750    3.0 0.00006  0.025    2   1.0    0
+   37 0  0  0 5000.  40    1.25E-03 985.6250    3.0 0.00006  0.025    1   1.0    0
 END PACKAGEDATA
 
 BEGIN CONNECTIONDATA
-#rno ic1 ic2 ic3
-   1  -2
-   2   1  -3
-   3   2  -4
-   4   3  -5 -10
-   5   4  -6
-   6   5  -7
-   7   6  -8
-   8   7  -9
-   9   8 -23
-  10   4 -11
-  11  10 -12
-  12  11 -13
-  13  12 -14
-  14  13 -15
-  15  14 -19
-  16 -17
-  17  16 -18
-  18  17 -19
-  19  15  18 -20
-  20  19 -21
-  21  20 -22
-  22  21 -23
-  23   9  22 -24
-  24  23 -25
-  25  24 -26
-  26  25 -27
-  27  26 -31
-  28 -29
-  29  28 -30
-  30  29 -31
-  31  27  30 -32
-  32  31 -33
-  33  32 -34
-  34  33 -35
-  35  34 -36
-  36  35 -37
-  37  36
+#ifno ic1 ic2 ic3
+    1  -2
+    2   1  -3
+    3   2  -4
+    4   3  -5 -10
+    5   4  -6
+    6   5  -7
+    7   6  -8
+    8   7  -9
+    9   8 -23
+   10   4 -11
+   11  10 -12
+   12  11 -13
+   13  12 -14
+   14  13 -15
+   15  14 -19
+   16 -17
+   17  16 -18
+   18  17 -19
+   19  15  18 -20
+   20  19 -21
+   21  20 -22
+   22  21 -23
+   23   9  22 -24
+   24  23 -25
+   25  24 -26
+   26  25 -27
+   27  26 -31
+   28 -29
+   29  28 -30
+   30  29 -31
+   31  27  30 -32
+   32  31 -33
+   33  32 -34
+   34  33 -35
+   35  34 -36
+   36  35 -37
+   37  36
 END CONNECTIONDATA
 
 BEGIN DIVERSIONS
-#  rno idv iconr cprior
+# ifno idv iconr cprior
      4   1    10 UPTO
 END DIVERSIONS
 
 BEGIN PERIOD 1
-# rno sfrsetting
+#ifno sfrsetting
     1 inflow 25.
    16 inflow 10.
    28 inflow 150.
diff --git a/doc/mf6io/mf6ivar/examples/gwf-sfr-example2.dat b/doc/mf6io/mf6ivar/examples/gwf-sfr-example2.dat
index a5b1e0f08f7..70121651009 100644
--- a/doc/mf6io/mf6ivar/examples/gwf-sfr-example2.dat
+++ b/doc/mf6io/mf6ivar/examples/gwf-sfr-example2.dat
@@ -13,17 +13,17 @@ BEGIN DIMENSIONS
 END DIMENSIONS
 
 BEGIN PACKAGEDATA
-#rno k  i j rlen rwid        rgrd      rtp   rbth     rhk   man  ncon ustrf  ndv  boundname
-   1 1  1 1 1000.  10    8.67E-04 1093.048    3.0 0.00003  0.03     1   1.0    0    trapezoidal
-   2 1  2 2 2000.  11    8.67E-04 1088.059    3.0 0.00003  0.03     2   1.0    0    trapezoidal
-   3 1  3 3 3000.  12    8.67E-04 1082.419    3.0 0.00003  0.03     2   1.0    0    trapezoidal
-   4 1  3 4 4000.  13    8.67E-04 1077.408    3.0 0.00003  0.03     2   1.0    0    trapezoidal
-   5 1  4 5 5000.  14    9.43E-04 1071.934    3.0 0.00003  0.03     2   1.0    0    rect
-   6 1  5 6 5000.  15    9.43E-04 1066.509    3.0 0.00003  0.03     2   1.0    0    rect
-   7 1  6 6 5000.  16    9.43E-04 1061.792    3.0 0.00003  0.03     2   1.0    0    rect
-   8 1  7 6 5000.  17    9.43E-04 1057.075    3.0 0.00003  0.03     2   1.0    0    rect
-   9 1  8 6 5000.  18    9.43E-04 1052.359    3.0 0.00003  0.03     2   1.0    0    rect
-  10 1  3 5 5000.  19    5.45E-04 1073.636    2.0 0.00003  0.03     1   0.0    0    rect
+#ifno k  i j rlen rwid        rgrd      rtp   rbth     rhk   man  ncon ustrf  ndv  boundname
+    1 1  1 1 1000.  10    8.67E-04 1093.048    3.0 0.00003  0.03     1   1.0    0    trapezoidal
+    2 1  2 2 2000.  11    8.67E-04 1088.059    3.0 0.00003  0.03     2   1.0    0    trapezoidal
+    3 1  3 3 3000.  12    8.67E-04 1082.419    3.0 0.00003  0.03     2   1.0    0    trapezoidal
+    4 1  3 4 4000.  13    8.67E-04 1077.408    3.0 0.00003  0.03     2   1.0    0    trapezoidal
+    5 1  4 5 5000.  14    9.43E-04 1071.934    3.0 0.00003  0.03     2   1.0    0    rect
+    6 1  5 6 5000.  15    9.43E-04 1066.509    3.0 0.00003  0.03     2   1.0    0    rect
+    7 1  6 6 5000.  16    9.43E-04 1061.792    3.0 0.00003  0.03     2   1.0    0    rect
+    8 1  7 6 5000.  17    9.43E-04 1057.075    3.0 0.00003  0.03     2   1.0    0    rect
+    9 1  8 6 5000.  18    9.43E-04 1052.359    3.0 0.00003  0.03     2   1.0    0    rect
+   10 1  3 5 5000.  19    5.45E-04 1073.636    2.0 0.00003  0.03     1   0.0    0    rect
 END PACKAGEDATA
 
 # CROSSSECTIONS BLOCK is optional
@@ -34,21 +34,21 @@ BEGIN CROSSSECTIONS
 END CROSSSECTIONS
 
 BEGIN CONNECTIONDATA
-#rno ic1 ic2 ic3
-   1  -2
-   2   1  -3
-   3   2  -4
-   4   3  -5
-   5   4  -6
-   6   5  -7
-   7   6  -8
-   8   7  -9
-   9   8 -10
-  10   9
+# ifno ic1 ic2 ic3
+     1  -2
+     2   1  -3
+     3   2  -4
+     4   3  -5
+     5   4  -6
+     6   5  -7
+     7   6  -8
+     8   7  -9
+     9   8 -10
+    10   9
 END CONNECTIONDATA
 
 BEGIN PERIOD 1
-# rno sfrsetting
-    1 inflow 25.
-    4 crosssection TAB6 FILEIN trapezoidal.tab
+# ifno sfrsetting
+     1 inflow 25.
+     4 crosssection TAB6 FILEIN trapezoidal.tab
 END PERIOD
diff --git a/doc/mf6io/mf6ivar/examples/gwt-lkt-example-obs.dat b/doc/mf6io/mf6ivar/examples/gwt-lkt-example-obs.dat
index 219b663b6f5..b099bbb1b3f 100644
--- a/doc/mf6io/mf6ivar/examples/gwt-lkt-example-obs.dat
+++ b/doc/mf6io/mf6ivar/examples/gwt-lkt-example-obs.dat
@@ -4,23 +4,24 @@ BEGIN options
 END options
 
 BEGIN continuous  FILEOUT  gwt_lkt02.lkt.obs.csv
-  lkt-1-conc  CONCENTRATION  1
-  lkt-1-extinflow  EXT-INFLOW  1
-  lkt-1-rain  RAINFALL  1
-  lkt-1-roff  RUNOFF  1
-  lkt-1-evap  EVAPORATION  1
-  lkt-1-wdrl  WITHDRAWAL  1
-  lkt-1-stor  STORAGE  1
-  lkt-1-const  CONSTANT  1
-  lkt-1-gwt1  LKT  1  1
-  lkt-1-gwt2  LKT  1  2
-  lkt-2-gwt1  LKT  2  1
-  lkt-1-mylake1  LKT  MYLAKE1
-  lkt-1-fjf  FLOW-JA-FACE  1  2
-  lkt-2-fjf  FLOW-JA-FACE  2  1
-  lkt-3-fjf  FLOW-JA-FACE  2  3
-  lkt-4-fjf  FLOW-JA-FACE  3  2
-  lkt-5-fjf  FLOW-JA-FACE  MYLAKE1
-  lkt-6-fjf  FLOW-JA-FACE  MYLAKE2
-  lkt-7-fjf  FLOW-JA-FACE  MYLAKE3
+# obs_name              obs_type  ID       ID2
+  lkt-1-conc       CONCENTRATION   1
+  lkt-1-extinflow  EXT-INFLOW      1
+  lkt-1-rain       RAINFALL        1
+  lkt-1-roff       RUNOFF          1
+  lkt-1-evap       EVAPORATION     1
+  lkt-1-wdrl       WITHDRAWAL      1
+  lkt-1-stor       STORAGE         1
+  lkt-1-const      CONSTANT        1
+  lkt-1-gwt1       LKT             1         1
+  lkt-1-gwt2       LKT             1         2
+  lkt-2-gwt1       LKT             2         1
+  lkt-1-mylake1    LKT             MYLAKE1   
+  lkt-1-fjf        FLOW-JA-FACE    1         2
+  lkt-2-fjf        FLOW-JA-FACE    2         1
+  lkt-3-fjf        FLOW-JA-FACE    2         3
+  lkt-4-fjf        FLOW-JA-FACE    3         2
+  lkt-5-fjf        FLOW-JA-FACE    MYLAKE1
+  lkt-6-fjf        FLOW-JA-FACE    MYLAKE2
+  lkt-7-fjf        FLOW-JA-FACE    MYLAKE3
 END continuous
diff --git a/doc/mf6io/mf6ivar/examples/gwt-lkt-example.dat b/doc/mf6io/mf6ivar/examples/gwt-lkt-example.dat
index 5e3706eb239..76e1f6986ee 100644
--- a/doc/mf6io/mf6ivar/examples/gwt-lkt-example.dat
+++ b/doc/mf6io/mf6ivar/examples/gwt-lkt-example.dat
@@ -11,10 +11,10 @@ BEGIN OPTIONS
 END OPTIONS
 
 BEGIN PACKAGEDATA
-# L             STRT             aux1             aux2    bname
-  1       0.00000000      99.00000000     999.00000000  MYLAKE1
-  2       0.00000000      99.00000000     999.00000000  MYLAKE2
-  3       0.00000000      99.00000000     999.00000000  MYLAKE3
+# ifno          STRT             aux1             aux2    bname
+     1    0.00000000      99.00000000     999.00000000  MYLAKE1
+     2    0.00000000      99.00000000     999.00000000  MYLAKE2
+     3    0.00000000      99.00000000     999.00000000  MYLAKE3
 END PACKAGEDATA
 
 BEGIN PERIOD  1
diff --git a/doc/mf6io/mf6ivar/examples/gwt-mwt-example-obs.dat b/doc/mf6io/mf6ivar/examples/gwt-mwt-example-obs.dat
index f5d2c250348..a968355aaf5 100644
--- a/doc/mf6io/mf6ivar/examples/gwt-mwt-example-obs.dat
+++ b/doc/mf6io/mf6ivar/examples/gwt-mwt-example-obs.dat
@@ -4,40 +4,41 @@ BEGIN options
 END options
 
 BEGIN continuous  FILEOUT  gwt_mwt_02.mwt.obs.csv
-  mwt1mwt  MWT  1  1
-  mwt2mwt  MWT  2  1
-  mwt3mwt  MWT  3  1
-  mwt4mwt  MWT  4  1
-  mwt1conc  CONCENTRATION  1
-  mwt2conc  CONCENTRATION  2
-  mwt3conc  CONCENTRATION  3
-  mwt4conc  CONCENTRATION  4
-  mwt1stor  STORAGE  1
-  mwt2stor  STORAGE  2
-  mwt3stor  STORAGE  3
-  mwt4stor  STORAGE  4
-  mwt1cnst  CONSTANT  1
-  mwt2cnst  CONSTANT  2
-  mwt3cnst  CONSTANT  3
-  mwt4cnst  CONSTANT  4
-  mwt1fmvr  FROM-MVR  1
-  mwt2fmvr  FROM-MVR  2
-  mwt3fmvr  FROM-MVR  3
-  mwt4fmvr  FROM-MVR  4
-  mwt1rate  RATE  1
-  mwt2rate  RATE  2
-  mwt3rate  RATE  3
-  mwt4rate  RATE  4
-  mwt1rtmv  RATE-TO-MVR  1
-  mwt2rtmv  RATE-TO-MVR  2
-  mwt3rtmv  RATE-TO-MVR  3
-  mwt4rtmv  RATE-TO-MVR  4
-  mwt1fwrt  FW-RATE  1
-  mwt2fwrt  FW-RATE  2
-  mwt3fwrt  FW-RATE  3
-  mwt4fwrt  FW-RATE  4
-  mwt1frtm  FW-RATE-TO-MVR  1
-  mwt2frtm  FW-RATE-TO-MVR  2
-  mwt3frtm  FW-RATE-TO-MVR  3
-  mwt4frtm  FW-RATE-TO-MVR  4
+# obs_name    obs_type         ID   ID2
+  mwt1mwt     MWT               1     1
+  mwt2mwt     MWT               2     1
+  mwt3mwt     MWT               3     1
+  mwt4mwt     MWT               4     1
+  mwt1conc    CONCENTRATION     1
+  mwt2conc    CONCENTRATION     2
+  mwt3conc    CONCENTRATION     3
+  mwt4conc    CONCENTRATION     4
+  mwt1stor    STORAGE           1
+  mwt2stor    STORAGE           2
+  mwt3stor    STORAGE           3
+  mwt4stor    STORAGE           4
+  mwt1cnst    CONSTANT          1
+  mwt2cnst    CONSTANT          2
+  mwt3cnst    CONSTANT          3
+  mwt4cnst    CONSTANT          4
+  mwt1fmvr    FROM-MVR          1
+  mwt2fmvr    FROM-MVR          2
+  mwt3fmvr    FROM-MVR          3
+  mwt4fmvr    FROM-MVR          4
+  mwt1rate    RATE              1
+  mwt2rate    RATE              2
+  mwt3rate    RATE              3
+  mwt4rate    RATE              4
+  mwt1rtmv    RATE-TO-MVR       1
+  mwt2rtmv    RATE-TO-MVR       2
+  mwt3rtmv    RATE-TO-MVR       3
+  mwt4rtmv    RATE-TO-MVR       4
+  mwt1fwrt    FW-RATE           1
+  mwt2fwrt    FW-RATE           2
+  mwt3fwrt    FW-RATE           3
+  mwt4fwrt    FW-RATE           4
+  mwt1frtm    FW-RATE-TO-MVR    1
+  mwt2frtm    FW-RATE-TO-MVR    2
+  mwt3frtm    FW-RATE-TO-MVR    3
+  mwt4frtm    FW-RATE-TO-MVR    4
 END continuous  FILEOUT  gwt_mwt_02.mwt.obs.csv
\ No newline at end of file
diff --git a/doc/mf6io/mf6ivar/examples/gwt-mwt-example.dat b/doc/mf6io/mf6ivar/examples/gwt-mwt-example.dat
index 111a30b3d37..c3157ad0dd5 100644
--- a/doc/mf6io/mf6ivar/examples/gwt-mwt-example.dat
+++ b/doc/mf6io/mf6ivar/examples/gwt-mwt-example.dat
@@ -11,10 +11,10 @@ BEGIN OPTIONS
 END OPTIONS
 
 BEGIN PACKAGEDATA
-# L             STRT             aux1             aux2    bname
-  1       0.00000000      99.00000000     999.00000000  MYWELL1
-  2       0.00000000      99.00000000     999.00000000  MYWELL2
-  3       0.00000000      99.00000000     999.00000000  MYWELL3
+# ifno          STRT             aux1             aux2    bname
+     1    0.00000000      99.00000000     999.00000000  MYWELL1
+     2    0.00000000      99.00000000     999.00000000  MYWELL2
+     3    0.00000000      99.00000000     999.00000000  MYWELL3
 END PACKAGEDATA
 
 BEGIN PERIOD  1
diff --git a/doc/mf6io/mf6ivar/examples/gwt-uzt-example-obs.dat b/doc/mf6io/mf6ivar/examples/gwt-uzt-example-obs.dat
index 8d52cf11160..5a9feb5dd1d 100644
--- a/doc/mf6io/mf6ivar/examples/gwt-uzt-example-obs.dat
+++ b/doc/mf6io/mf6ivar/examples/gwt-uzt-example-obs.dat
@@ -4,9 +4,10 @@ BEGIN options
 END options
 
 BEGIN continuous  FILEOUT  gwt_02.uzt.obs.csv
-  mwt-1-conc  CONCENTRATION  1
-  mwt-1-stor  STORAGE  1
-  mwt-1-gwt1  UZT  1
-  mwt-1-gwt2  UZT  2
-  mwt-2-gwt1  UZT  3
+# obs_name      obs_type         ID
+  mwt-1-conc    CONCENTRATION     1
+  mwt-1-stor    STORAGE           1
+  mwt-1-gwt1    UZT               1
+  mwt-1-gwt2    UZT               2
+  mwt-2-gwt1    UZT               3
 END continuous
diff --git a/doc/mf6io/mf6ivar/examples/gwt-uzt-example.dat b/doc/mf6io/mf6ivar/examples/gwt-uzt-example.dat
index 5a525d35959..5896535f8d7 100644
--- a/doc/mf6io/mf6ivar/examples/gwt-uzt-example.dat
+++ b/doc/mf6io/mf6ivar/examples/gwt-uzt-example.dat
@@ -11,10 +11,10 @@ BEGIN OPTIONS
 END OPTIONS
 
 BEGIN PACKAGEDATA
-# L             STRT             aux1             aux2    bname
-  1       0.00000000      99.00000000     999.00000000  MYUZFCELL1
-  2       0.00000000      99.00000000     999.00000000  MYUZFCELL2
-  3       0.00000000      99.00000000     999.00000000  MYUZFCELL3
+# ifno         STRT             aux1             aux2       bname
+     1   0.00000000      99.00000000     999.00000000  MYUZFCELL1
+     2   0.00000000      99.00000000     999.00000000  MYUZFCELL2
+     3   0.00000000      99.00000000     999.00000000  MYUZFCELL3
 END PACKAGEDATA
 
 BEGIN PERIOD  1
diff --git a/doc/mf6io/mf6ivar/md/deprecations.md b/doc/mf6io/mf6ivar/md/deprecations.md
new file mode 100644
index 00000000000..5c3429bcc9f
--- /dev/null
+++ b/doc/mf6io/mf6ivar/md/deprecations.md
@@ -0,0 +1,14 @@
+#### Deprecations
+
+The following table lists deprecated options and the versions in which they were deprecated and (optionally) removed.
+
+| Model-Package | Option | Deprecated | Removed |
+|:--------------|:-------|:-----------|:--------|
+| gwf-sfr | unit_conversion | 6.4.2 |  |
+| sln-ims | csv_output_filerecord | 6.1.1 |  |
+| sln-ims | csv_output | 6.1.1 |  |
+| sln-ims | csvfile | 6.1.1 |  |
+| sln-ims | outer_hclose | 6.1.1 |  |
+| sln-ims | outer_rclosebnd | 6.1.1 |  |
+| sln-ims | inner_hclose | 6.1.1 |  |
+
diff --git a/doc/mf6io/mf6ivar/md/mf6ivar.md b/doc/mf6io/mf6ivar/md/mf6ivar.md
index 796bc5bcfeb..a1a6b95f5ac 100644
--- a/doc/mf6io/mf6ivar/md/mf6ivar.md
+++ b/doc/mf6io/mf6ivar/md/mf6ivar.md
@@ -321,6 +321,7 @@
 | GWF | CHD | OPTIONS | TS6_FILENAME | STRING | defines a time-series file defining time series that can be used to assign time-varying values. See the ``Time-Variable Input'' section for instructions on using the time-series capability. |
 | GWF | CHD | OPTIONS | OBS6 | KEYWORD | keyword to specify that record corresponds to an observations file. |
 | GWF | CHD | OPTIONS | OBS6_FILENAME | STRING | name of input file to define observations for the constant-head package. See the ``Observation utility'' section for instructions for preparing observation input files. Tables \ref{table:gwf-obstypetable} and \ref{table:gwt-obstypetable} lists observation type(s) supported by the constant-head package. |
+| GWF | CHD | OPTIONS | DEV_NO_NEWTON | KEYWORD | turn off Newton for unconfined cells |
 | GWF | CHD | DIMENSIONS | MAXBOUND | INTEGER | integer value specifying the maximum number of constant-head cells that will be specified for use during any stress period. |
 | GWF | CHD | PERIOD | IPER | INTEGER | integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block. |
 | GWF | CHD | PERIOD | CELLID | INTEGER (NCELLDIM) | is the cell identifier, and depends on the type of grid that is used for the simulation.  For a structured grid that uses the DIS input file, CELLID is the layer, row, and column.   For a grid that uses the DISV input file, CELLID is the layer and CELL2D number.  If the model uses the unstructured discretization (DISU) input file, CELLID is the node number for the cell. |
@@ -362,6 +363,7 @@
 | GWF | DRN | OPTIONS | OBS6 | KEYWORD | keyword to specify that record corresponds to an observations file. |
 | GWF | DRN | OPTIONS | OBS6_FILENAME | STRING | name of input file to define observations for the Drain package. See the ``Observation utility'' section for instructions for preparing observation input files. Tables \ref{table:gwf-obstypetable} and \ref{table:gwt-obstypetable} lists observation type(s) supported by the Drain package. |
 | GWF | DRN | OPTIONS | MOVER | KEYWORD | keyword to indicate that this instance of the Drain Package can be used with the Water Mover (MVR) Package.  When the MOVER option is specified, additional memory is allocated within the package to store the available, provided, and received water. |
+| GWF | DRN | OPTIONS | DEV_CUBIC_SCALING | KEYWORD | cubic-scaling is used to scale the drain conductance |
 | GWF | DRN | DIMENSIONS | MAXBOUND | INTEGER | integer value specifying the maximum number of drains cells that will be specified for use during any stress period. |
 | GWF | DRN | PERIOD | IPER | INTEGER | integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block. |
 | GWF | DRN | PERIOD | CELLID | INTEGER (NCELLDIM) | is the cell identifier, and depends on the type of grid that is used for the simulation.  For a structured grid that uses the DIS input file, CELLID is the layer, row, and column.   For a grid that uses the DISV input file, CELLID is the layer and CELL2D number.  If the model uses the unstructured discretization (DISU) input file, CELLID is the node number for the cell. |
@@ -435,7 +437,7 @@
 | GWF | RCHA | OPTIONS | SAVE_FLOWS | KEYWORD | keyword to indicate that recharge flow terms will be written to the file specified with ``BUDGET FILEOUT'' in Output Control. |
 | GWF | RCHA | OPTIONS | TAS6 | KEYWORD | keyword to specify that record corresponds to a time-array-series file. |
 | GWF | RCHA | OPTIONS | FILEIN | KEYWORD | keyword to specify that an input filename is expected next. |
-| GWF | RCHA | OPTIONS | TAS6_FILENAME | STRING | defines a time-array-series file defining a time-array series that can be used to assign time-varying values. See the Time-Variable Input section for instructions on using the time-array series capability. |
+| GWF | RCHA | OPTIONS | TAS6_FILENAME | STRING | defines a time-array-series file defining a time-array series that can be used to assign time-varying values. See the ``Time-Variable Input'' section for instructions on using the time-array series capability. |
 | GWF | RCHA | OPTIONS | OBS6 | KEYWORD | keyword to specify that record corresponds to an observations file. |
 | GWF | RCHA | OPTIONS | OBS6_FILENAME | STRING | name of input file to define observations for the Recharge package. See the ``Observation utility'' section for instructions for preparing observation input files. Tables \ref{table:gwf-obstypetable} and \ref{table:gwt-obstypetable} lists observation type(s) supported by the Recharge package. |
 | GWF | RCHA | PERIOD | IPER | INTEGER | integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block. |
@@ -484,7 +486,7 @@
 | GWF | EVTA | PERIOD | SURFACE | DOUBLE PRECISION (NCOL*NROW; NCPL) | is the elevation of the ET surface ($L$). |
 | GWF | EVTA | PERIOD | RATE | DOUBLE PRECISION (NCOL*NROW; NCPL) | is the maximum ET flux rate ($LT^{-1}$). |
 | GWF | EVTA | PERIOD | DEPTH | DOUBLE PRECISION (NCOL*NROW; NCPL) | is the ET extinction depth ($L$). |
-| GWF | EVTA | PERIOD | AUX(IAUX) | DOUBLE PRECISION (NCOL*NROW; NCPL) | is an array of values for auxiliary variable AUX(IAUX), where iaux is a value from 1 to NAUX, and AUX(IAUX) must be listed as part of the auxiliary variables.  A separate array can be specified for each auxiliary variable.  If an array is not specified for an auxiliary variable, then a value of zero is assigned.  If the value specified here for the auxiliary variable is the same as auxmultname, then the evapotranspiration rate will be multiplied by this array. |
+| GWF | EVTA | PERIOD | AUX | DOUBLE PRECISION (NCOL*NROW; NCPL) | is an array of values for auxiliary variable AUX(IAUX), where iaux is a value from 1 to NAUX, and AUX(IAUX) must be listed as part of the auxiliary variables.  A separate array can be specified for each auxiliary variable.  If an array is not specified for an auxiliary variable, then a value of zero is assigned.  If the value specified here for the auxiliary variable is the same as auxmultname, then the evapotranspiration rate will be multiplied by this array. |
 | GWF | MAW | OPTIONS | AUXILIARY | STRING (NAUX) | defines an array of one or more auxiliary variable names.  There is no limit on the number of auxiliary variables that can be provided on this line; however, lists of information provided in subsequent blocks must have a column of data for each auxiliary variable name defined here.   The number of auxiliary variables detected on this line determines the value for naux.  Comments cannot be provided anywhere on this line as they will be interpreted as auxiliary variable names.  Auxiliary variables may not be used by the package, but they will be available for use by other parts of the program.  The program will terminate with an error if auxiliary variables are specified on more than one line in the options block. |
 | GWF | MAW | OPTIONS | BOUNDNAMES | KEYWORD | keyword to indicate that boundary names may be provided with the list of multi-aquifer well cells. |
 | GWF | MAW | OPTIONS | PRINT_INPUT | KEYWORD | keyword to indicate that the list of multi-aquifer well information will be written to the listing file immediately after it is read. |
@@ -512,30 +514,30 @@
 | GWF | MAW | OPTIONS | OBS6_FILENAME | STRING | name of input file to define observations for the MAW package. See the ``Observation utility'' section for instructions for preparing observation input files. Tables \ref{table:gwf-obstypetable} and \ref{table:gwt-obstypetable} lists observation type(s) supported by the MAW package. |
 | GWF | MAW | OPTIONS | MOVER | KEYWORD | keyword to indicate that this instance of the MAW Package can be used with the Water Mover (MVR) Package.  When the MOVER option is specified, additional memory is allocated within the package to store the available, provided, and received water. |
 | GWF | MAW | DIMENSIONS | NMAWWELLS | INTEGER | integer value specifying the number of multi-aquifer wells that will be simulated for all stress periods. |
-| GWF | MAW | PACKAGEDATA | WELLNO | INTEGER | integer value that defines the well number associated with the specified PACKAGEDATA data on the line. WELLNO must be greater than zero and less than or equal to NMAWWELLS. Multi-aquifer well information must be specified for every multi-aquifer well or the program will terminate with an error.  The program will also terminate with an error if information for a multi-aquifer well is specified more than once. |
+| GWF | MAW | PACKAGEDATA | IFNO | INTEGER | integer value that defines the feature (well) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NMAWWELLS. Multi-aquifer well information must be specified for every multi-aquifer well or the program will terminate with an error.  The program will also terminate with an error if information for a multi-aquifer well is specified more than once. |
 | GWF | MAW | PACKAGEDATA | RADIUS | DOUBLE PRECISION | radius for the multi-aquifer well. The program will terminate with an error if the radius is less than or equal to zero. |
 | GWF | MAW | PACKAGEDATA | BOTTOM | DOUBLE PRECISION | bottom elevation of the multi-aquifer well. If CONDEQN is SPECIFIED, THIEM, SKIN, or COMPOSITE, BOTTOM is set to the cell bottom in the lowermost GWF cell connection in cases where the specified well bottom is above the bottom of this GWF cell. If CONDEQN is MEAN, BOTTOM is set to the lowermost GWF cell connection screen bottom in cases where the specified well bottom is above this value. The bottom elevation defines the lowest well head that will be simulated when the NEWTON UNDER\_RELAXATION option is specified in the GWF model name file. The bottom elevation is also used to calculate volumetric storage in the well. |
 | GWF | MAW | PACKAGEDATA | STRT | DOUBLE PRECISION | starting head for the multi-aquifer well. The program will terminate with an error if the starting head is less than the specified well bottom. |
 | GWF | MAW | PACKAGEDATA | CONDEQN | STRING | character string that defines the conductance equation that is used to calculate the saturated conductance for the multi-aquifer well. Possible multi-aquifer well CONDEQN strings include: SPECIFIED--character keyword to indicate the multi-aquifer well saturated conductance will be specified.  THIEM--character keyword to indicate the multi-aquifer well saturated conductance will be calculated using the Thiem equation, which considers the cell top and bottom, aquifer hydraulic conductivity, and effective cell and well radius.  SKIN--character keyword to indicate that the multi-aquifer well saturated conductance will be calculated using the cell top and bottom, aquifer and screen hydraulic conductivity, and well and skin radius.  CUMULATIVE--character keyword to indicate that the multi-aquifer well saturated conductance will be calculated using a combination of the Thiem and SKIN equations.  MEAN--character keyword to indicate the multi-aquifer well saturated conductance will be calculated using the aquifer and screen top and bottom, aquifer and screen hydraulic conductivity, and well and skin radius. The CUMULATIVE conductance equation is identical to the SKIN LOSSTYPE in the Multi-Node Well (MNW2) package for MODFLOW-2005. The program will terminate with an error condition if CONDEQN is SKIN or CUMULATIVE and the calculated saturated conductance is less than zero; if an error condition occurs, it is suggested that the THEIM or MEAN conductance equations be used for these multi-aquifer wells. |
-| GWF | MAW | PACKAGEDATA | NGWFNODES | INTEGER | integer value that defines the number of GWF nodes connected to this (WELLNO) multi-aquifer well. NGWFNODES must be greater than zero. |
+| GWF | MAW | PACKAGEDATA | NGWFNODES | INTEGER | integer value that defines the number of GWF nodes connected to this (IFNO) multi-aquifer well. NGWFNODES must be greater than zero. |
 | GWF | MAW | PACKAGEDATA | AUX | DOUBLE PRECISION (NAUX) | represents the values of the auxiliary variables for each multi-aquifer well. The values of auxiliary variables must be present for each multi-aquifer well. The values must be specified in the order of the auxiliary variables specified in the OPTIONS block.  If the package supports time series and the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
 | GWF | MAW | PACKAGEDATA | BOUNDNAME | STRING | name of the multi-aquifer well cell.  BOUNDNAME is an ASCII character variable that can contain as many as 40 characters.  If BOUNDNAME contains spaces in it, then the entire name must be enclosed within single quotes. |
-| GWF | MAW | CONNECTIONDATA | WELLNO | INTEGER | integer value that defines the well number associated with the specified CONNECTIONDATA data on the line. WELLNO must be greater than zero and less than or equal to NMAWWELLS. Multi-aquifer well connection information must be specified for every multi-aquifer well connection to the GWF model (NGWFNODES) or the program will terminate with an error.  The program will also terminate with an error if connection information for a multi-aquifer well connection to the GWF model is specified more than once. |
-| GWF | MAW | CONNECTIONDATA | ICON | INTEGER | integer value that defines the GWF connection number for this multi-aquifer well connection entry. ICONN must be greater than zero and less than or equal to NGWFNODES for multi-aquifer well WELLNO. |
+| GWF | MAW | CONNECTIONDATA | IFNO | INTEGER | integer value that defines the feature (well) number associated with the specified CONNECTIONDATA data on the line. IFNO must be greater than zero and less than or equal to NMAWWELLS. Multi-aquifer well connection information must be specified for every multi-aquifer well connection to the GWF model (NGWFNODES) or the program will terminate with an error.  The program will also terminate with an error if connection information for a multi-aquifer well connection to the GWF model is specified more than once. |
+| GWF | MAW | CONNECTIONDATA | ICON | INTEGER | integer value that defines the GWF connection number for this multi-aquifer well connection entry. ICONN must be greater than zero and less than or equal to NGWFNODES for multi-aquifer well IFNO. |
 | GWF | MAW | CONNECTIONDATA | CELLID | INTEGER (NCELLDIM) | is the cell identifier, and depends on the type of grid that is used for the simulation.  For a structured grid that uses the DIS input file, CELLID is the layer, row, and column.   For a grid that uses the DISV input file, CELLID is the layer and CELL2D number.  If the model uses the unstructured discretization (DISU) input file, CELLID is the node number for the cell. One or more screened intervals can be connected to the same CELLID if CONDEQN for a well is MEAN. The program will terminate with an error if MAW wells using SPECIFIED, THIEM, SKIN, or CUMULATIVE conductance equations have more than one connection to the same CELLID. |
 | GWF | MAW | CONNECTIONDATA | SCRN_TOP | DOUBLE PRECISION | value that defines the top elevation of the screen for the multi-aquifer well connection. If CONDEQN is SPECIFIED, THIEM, SKIN, or COMPOSITE, SCRN\_TOP can be any value and is set to the top of the cell. If CONDEQN is MEAN, SCRN\_TOP is set to the multi-aquifer well connection cell top if the specified value is greater than the cell top. The program will terminate with an error if the screen top is less than the screen bottom. |
-| GWF | MAW | CONNECTIONDATA | SCRN_BOT | DOUBLE PRECISION | value that defines the bottom elevation of the screen for the multi-aquifer well connection. If CONDEQN is SPECIFIED, THIEM, SKIN, or COMPOSITE, SCRN\_BOT can be any value is set to the bottom of the cell. If CONDEQN is MEAN, SCRN\_BOT is set to the multi-aquifer well connection cell bottom if the specified value is less than the cell bottom. The program will terminate with an error if the screen bottom is greater than the screen top. |
+| GWF | MAW | CONNECTIONDATA | SCRN_BOT | DOUBLE PRECISION | value that defines the bottom elevation of the screen for the multi-aquifer well connection. If CONDEQN is SPECIFIED, THIEM, SKIN, or COMPOSITE, SCRN\_BOT can be any value and is set to the bottom of the cell. If CONDEQN is MEAN, SCRN\_BOT is set to the multi-aquifer well connection cell bottom if the specified value is less than the cell bottom. The program will terminate with an error if the screen bottom is greater than the screen top. |
 | GWF | MAW | CONNECTIONDATA | HK_SKIN | DOUBLE PRECISION | value that defines the skin (filter pack) hydraulic conductivity (if CONDEQN for the multi-aquifer well is SKIN, CUMULATIVE, or MEAN) or conductance (if CONDEQN for the multi-aquifer well is SPECIFIED) for each GWF node connected to the multi-aquifer well (NGWFNODES). If CONDEQN is SPECIFIED, HK\_SKIN must be greater than or equal to zero.  HK\_SKIN can be any value if CONDEQN is THIEM. Otherwise, HK\_SKIN must be greater than zero. If CONDEQN is SKIN, the contrast between the cell transmissivity (the product of geometric mean horizontal hydraulic conductivity and the cell thickness) and the well transmissivity (the product of HK\_SKIN and the screen thicknesses) must be greater than one in node CELLID or the program will terminate with an error condition; if an error condition occurs, it is suggested that the HK\_SKIN be reduced to a value less than K11 and K22 in node CELLID or the THEIM or MEAN conductance equations be used for these multi-aquifer wells. |
 | GWF | MAW | CONNECTIONDATA | RADIUS_SKIN | DOUBLE PRECISION | real value that defines the skin radius (filter pack radius) for the multi-aquifer well. RADIUS\_SKIN can be any value if CONDEQN is SPECIFIED or THIEM. If CONDEQN is SKIN, CUMULATIVE, or MEAN, the program will terminate with an error if  RADIUS\_SKIN is less than or equal to the RADIUS for the multi-aquifer well. |
 | GWF | MAW | PERIOD | IPER | INTEGER | integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block. |
-| GWF | MAW | PERIOD | WELLNO | INTEGER | integer value that defines the well number associated with the specified PERIOD data on the line. WELLNO must be greater than zero and less than or equal to NMAWWELLS. |
+| GWF | MAW | PERIOD | IFNO | INTEGER | integer value that defines the well number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NMAWWELLS. |
 | GWF | MAW | PERIOD | MAWSETTING | KEYSTRING | line of information that is parsed into a keyword and values.  Keyword values that can be used to start the MAWSETTING string include: STATUS, FLOWING\_WELL, RATE, WELL\_HEAD, HEAD\_LIMIT, SHUT\_OFF, RATE\_SCALING, and AUXILIARY. |
 | GWF | MAW | PERIOD | STATUS | STRING | keyword option to define well status.  STATUS can be ACTIVE, INACTIVE, or CONSTANT. By default, STATUS is ACTIVE. |
 | GWF | MAW | PERIOD | FLOWING_WELL | KEYWORD | keyword to indicate the well is a flowing well.  The FLOWING\_WELL option can be used to simulate flowing wells when the simulated well head exceeds the specified drainage elevation. |
 | GWF | MAW | PERIOD | FWELEV | DOUBLE PRECISION | elevation used to determine whether or not the well is flowing. |
 | GWF | MAW | PERIOD | FWCOND | DOUBLE PRECISION | conductance used to calculate the discharge of a free flowing well.  Flow occurs when the head in the well is above the well top elevation (FWELEV). |
 | GWF | MAW | PERIOD | FWRLEN | DOUBLE PRECISION | length used to reduce the conductance of the flowing well.  When the head in the well drops below the well top plus the reduction length, then the conductance is reduced.  This reduction length can be used to improve the stability of simulations with flowing wells so that there is not an abrupt change in flowing well rates. |
-| GWF | MAW | PERIOD | RATE | DOUBLE PRECISION | is the volumetric pumping rate for the multi-aquifer well. A positive value indicates recharge and a negative value indicates discharge (pumping). RATE only applies to active (IBOUND $>$ 0) multi-aquifer wells. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. By default, the RATE for each multi-aquifer well is zero. |
+| GWF | MAW | PERIOD | RATE | DOUBLE PRECISION | is the volumetric pumping rate for the multi-aquifer well. A positive value indicates recharge and a negative value indicates discharge (pumping). RATE only applies to active (STATUS is ACTIVE) multi-aquifer wells. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. By default, the RATE for each multi-aquifer well is zero. |
 | GWF | MAW | PERIOD | WELL_HEAD | DOUBLE PRECISION | is the head in the multi-aquifer well. WELL\_HEAD is only applied to constant head (STATUS is CONSTANT) and inactive (STATUS is INACTIVE) multi-aquifer wells. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. The program will terminate with an error if WELL\_HEAD is less than the bottom of the well. |
 | GWF | MAW | PERIOD | HEAD_LIMIT | STRING | is the limiting water level (head) in the well, which is the minimum of the well RATE or the well inflow rate from the aquifer. HEAD\_LIMIT can be applied to extraction wells (RATE $<$ 0) or injection wells (RATE $>$ 0). HEAD\_LIMIT can be deactivated by specifying the text string `OFF'. The HEAD\_LIMIT option is based on the HEAD\_LIMIT functionality available in the MNW2~\citep{konikow2009} package for MODFLOW-2005. The HEAD\_LIMIT option has been included to facilitate backward compatibility with previous versions of MODFLOW but use of the RATE\_SCALING option instead of the HEAD\_LIMIT option is recommended. By default, HEAD\_LIMIT is `OFF'. |
 | GWF | MAW | PERIOD | SHUT_OFF | KEYWORD | keyword for activating well shut off capability.  Subsequent values define the minimum and maximum pumping rate that a well must exceed to shutoff or reactivate a well, respectively, during a stress period. SHUT\_OFF is only applied to injection wells (RATE$<0$) and if HEAD\_LIMIT is specified (not set to `OFF').  If HEAD\_LIMIT is specified, SHUT\_OFF can be deactivated by specifying a minimum value equal to zero. The SHUT\_OFF option is based on the SHUT\_OFF functionality available in the MNW2~\citep{konikow2009} package for MODFLOW-2005. The SHUT\_OFF option has been included to facilitate backward compatibility with previous versions of MODFLOW but use of the RATE\_SCALING option instead of the SHUT\_OFF option is recommended. By default, SHUT\_OFF is not used. |
@@ -575,32 +577,32 @@
 | GWF | SFR | OPTIONS | LENGTH_CONVERSION | DOUBLE PRECISION | real value that is used to convert user-specified Manning's roughness coefficients from meters to model length units. LENGTH\_CONVERSION should be set to 3.28081, 1.0, and 100.0 when using length units (LENGTH\_UNITS) of feet, meters, or centimeters in the simulation, respectively. LENGTH\_CONVERSION does not need to be specified if LENGTH\_UNITS are meters. |
 | GWF | SFR | OPTIONS | TIME_CONVERSION | DOUBLE PRECISION | real value that is used to convert user-specified Manning's roughness coefficients from seconds to model time units. TIME\_CONVERSION should be set to 1.0, 60.0, 3,600.0, 86,400.0, and 31,557,600.0 when using time units (TIME\_UNITS) of seconds, minutes, hours, days, or years in the simulation, respectively. TIME\_CONVERSION does not need to be specified if TIME\_UNITS are seconds. |
 | GWF | SFR | DIMENSIONS | NREACHES | INTEGER | integer value specifying the number of stream reaches.  There must be NREACHES entries in the PACKAGEDATA block. |
-| GWF | SFR | PACKAGEDATA | RNO | INTEGER | integer value that defines the reach number associated with the specified PACKAGEDATA data on the line. RNO must be greater than zero and less than or equal to NREACHES. Reach information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if information for a reach is specified more than once. |
-| GWF | SFR | PACKAGEDATA | CELLID | INTEGER (NCELLDIM) | The keyword `NONE' must be specified for reaches that are not connected to an underlying GWF cell. The keyword `NONE' is used for reaches that are in cells that have IDOMAIN values less than one or are in areas not covered by the GWF model grid. Reach-aquifer flow is not calculated if the keyword `NONE' is specified. |
+| GWF | SFR | PACKAGEDATA | IFNO | INTEGER | integer value that defines the feature (reach) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NREACHES. Reach information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if information for a reach is specified more than once. |
+| GWF | SFR | PACKAGEDATA | CELLID | INTEGER (NCELLDIM) | is the cell identifier, and depends on the type of grid that is used for the simulation. For a structured grid that uses the DIS input file, CELLID is the layer, row, and column. For a grid that uses the DISV input file, CELLID is the layer and CELL2D number. If the model uses the unstructured discretization (DISU) input file, CELLID is the node number for the cell. For reaches that are not connected to an underlying GWF cell, a zero should be specified for each grid dimension. For example, for a DIS grid a CELLID of 0 0 0 should be specified. Reach-aquifer flow is not calculated for unconnected reaches. The keyword NONE can be still be specified to identify unconnected reaches for backward compatibility with previous versions of MODFLOW 6 but eventually NONE will be deprecated and will cause MODFLOW 6 to terminate with an error. |
 | GWF | SFR | PACKAGEDATA | RLEN | DOUBLE PRECISION | real value that defines the reach length. RLEN must be greater than zero. |
 | GWF | SFR | PACKAGEDATA | RWID | DOUBLE PRECISION | real value that defines the reach width. RWID must be greater than zero. |
 | GWF | SFR | PACKAGEDATA | RGRD | DOUBLE PRECISION | real value that defines the stream gradient (slope) across the reach. RGRD must be greater than zero. |
 | GWF | SFR | PACKAGEDATA | RTP | DOUBLE PRECISION | real value that defines the bottom elevation of the reach. |
-| GWF | SFR | PACKAGEDATA | RBTH | DOUBLE PRECISION | real value that defines the thickness of the reach streambed. RBTH can be any value if CELLID is `NONE'. Otherwise, RBTH must be greater than zero. |
-| GWF | SFR | PACKAGEDATA | RHK | DOUBLE PRECISION | real value that defines the hydraulic conductivity of the reach streambed. RHK can be any positive value if CELLID is `NONE'. Otherwise, RHK must be greater than zero. |
+| GWF | SFR | PACKAGEDATA | RBTH | DOUBLE PRECISION | real value that defines the thickness of the reach streambed. RBTH can be any value if the reach is not connected to an underlying GWF cell. Otherwise, RBTH must be greater than zero. |
+| GWF | SFR | PACKAGEDATA | RHK | DOUBLE PRECISION | real value that defines the hydraulic conductivity of the reach streambed. RHK can be any positive value if the reach is not connected to an underlying GWF cell. Otherwise, RHK must be greater than zero. |
 | GWF | SFR | PACKAGEDATA | MAN | STRING | real or character value that defines the Manning's roughness coefficient for the reach. MAN must be greater than zero.  If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
-| GWF | SFR | PACKAGEDATA | NCON | INTEGER | integer value that defines the number of reaches connected to the reach.  If a value of zero is specified for NCON an entry for RNO is still required in the subsequent CONNECTIONDATA block. |
+| GWF | SFR | PACKAGEDATA | NCON | INTEGER | integer value that defines the number of reaches connected to the reach.  If a value of zero is specified for NCON an entry for IFNO is still required in the subsequent CONNECTIONDATA block. |
 | GWF | SFR | PACKAGEDATA | USTRF | DOUBLE PRECISION | real value that defines the fraction of upstream flow from each upstream reach that is applied as upstream inflow to the reach. The sum of all USTRF values for all reaches connected to the same upstream reach must be equal to one and USTRF must be greater than or equal to zero. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
 | GWF | SFR | PACKAGEDATA | NDV | INTEGER | integer value that defines the number of downstream diversions for the reach. |
 | GWF | SFR | PACKAGEDATA | AUX | DOUBLE PRECISION (NAUX) | represents the values of the auxiliary variables for each stream reach. The values of auxiliary variables must be present for each stream reach. The values must be specified in the order of the auxiliary variables specified in the OPTIONS block.  If the package supports time series and the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
 | GWF | SFR | PACKAGEDATA | BOUNDNAME | STRING | name of the stream reach cell.  BOUNDNAME is an ASCII character variable that can contain as many as 40 characters.  If BOUNDNAME contains spaces in it, then the entire name must be enclosed within single quotes. |
-| GWF | SFR | CROSSSECTIONS | RNO | INTEGER | integer value that defines the reach number associated with the specified cross-section table file on the line. RNO must be greater than zero and less than or equal to NREACHES. The program will also terminate with an error if table information for a reach is specified more than once. |
+| GWF | SFR | CROSSSECTIONS | IFNO | INTEGER | integer value that defines the feature (reach) number associated with the specified cross-section table file on the line. IFNO must be greater than zero and less than or equal to NREACHES. The program will also terminate with an error if table information for a reach is specified more than once. |
 | GWF | SFR | CROSSSECTIONS | TAB6 | KEYWORD | keyword to specify that record corresponds to a cross-section table file. |
 | GWF | SFR | CROSSSECTIONS | FILEIN | KEYWORD | keyword to specify that an input filename is expected next. |
 | GWF | SFR | CROSSSECTIONS | TAB6_FILENAME | STRING | character string that defines the path and filename for the file containing cross-section table data for the reach. The TAB6\_FILENAME file includes the number of entries in the file and the station elevation data in terms of the fractional width and the reach depth. Instructions for creating the TAB6\_FILENAME input file are provided in SFR Reach Cross-Section Table Input File section. |
-| GWF | SFR | CONNECTIONDATA | RNO | INTEGER | integer value that defines the reach number associated with the specified CONNECTIONDATA data on the line. RNO must be greater than zero and less than or equal to NREACHES. Reach connection information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if connection information for a reach is specified more than once. |
-| GWF | SFR | CONNECTIONDATA | IC | INTEGER (NCON(RNO)) | integer value that defines the reach number of the reach connected to the current reach and whether it is connected to the upstream or downstream end of the reach. Negative IC numbers indicate connected reaches are connected to the downstream end of the current reach. Positive IC numbers indicate connected reaches are connected to the upstream end of the current reach. The absolute value of IC must be greater than zero and less than or equal to NREACHES. IC should not be specified when NCON is zero but must be specified otherwise. |
-| GWF | SFR | DIVERSIONS | RNO | INTEGER | integer value that defines the reach number associated with the specified DIVERSIONS data on the line. RNO must be greater than zero and less than or equal to NREACHES.  Reach diversion information must be specified for every reach with a NDV value greater than 0 or the program will terminate with an error.  The program will also terminate with an error if diversion information for a given reach diversion is specified more than once. |
-| GWF | SFR | DIVERSIONS | IDV | INTEGER | integer value that defines the downstream diversion number for the diversion for reach RNO. IDV must be greater than zero and less than or equal to NDV for reach RNO. |
-| GWF | SFR | DIVERSIONS | ICONR | INTEGER | integer value that defines the downstream reach that will receive the diverted water. IDV must be greater than zero and less than or equal to NREACHES. Furthermore, reach  ICONR must be a downstream connection for reach RNO. |
-| GWF | SFR | DIVERSIONS | CPRIOR | STRING | character string value that defines the the prioritization system for the diversion, such as when insufficient water is available to meet all diversion stipulations, and is used in conjunction with the value of FLOW value specified in the STRESS\_PERIOD\_DATA section. Available diversion options include:  (1) CPRIOR = `FRACTION', then the amount of the diversion is computed as a fraction of the streamflow leaving reach RNO ($Q_{DS}$); in this case, 0.0 $\le$ DIVFLOW $\le$ 1.0.  (2) CPRIOR = `EXCESS', a diversion is made only if $Q_{DS}$ for reach RNO exceeds the value of DIVFLOW. If this occurs, then the quantity of water diverted is the excess flow ($Q_{DS} -$ DIVFLOW) and $Q_{DS}$ from reach RNO is set equal to DIVFLOW. This represents a flood-control type of diversion, as described by Danskin and Hanson (2002). (3) CPRIOR = `THRESHOLD', then if $Q_{DS}$ in reach RNO is less than the specified diversion flow DIVFLOW, no water is diverted from reach RNO. If $Q_{DS}$ in reach RNO is greater than or equal to DIVFLOW, DIVFLOW is diverted and $Q_{DS}$ is set to the remainder ($Q_{DS} -$ DIVFLOW)). This approach assumes that once flow in the stream is sufficiently low, diversions from the stream cease, and is the `priority' algorithm that originally was programmed into the STR1 Package (Prudic, 1989).  (4) CPRIOR = `UPTO' -- if $Q_{DS}$ in reach RNO is greater than or equal to the specified diversion flow DIVFLOW, $Q_{DS}$ is reduced by DIVFLOW. If $Q_{DS}$ in reach RNO is less than DIVFLOW, DIVFLOW is set to $Q_{DS}$ and there will be no flow available for reaches connected to downstream end of reach RNO. |
+| GWF | SFR | CONNECTIONDATA | IFNO | INTEGER | integer value that defines the feature (reach) number associated with the specified CONNECTIONDATA data on the line. IFNO must be greater than zero and less than or equal to NREACHES. Reach connection information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if connection information for a reach is specified more than once. |
+| GWF | SFR | CONNECTIONDATA | IC | INTEGER (NCON(IFNO)) | integer value that defines the reach number of the reach connected to the current reach and whether it is connected to the upstream or downstream end of the reach. Negative IC numbers indicate connected reaches are connected to the downstream end of the current reach. Positive IC numbers indicate connected reaches are connected to the upstream end of the current reach. The absolute value of IC must be greater than zero and less than or equal to NREACHES. IC should not be specified when NCON is zero but must be specified otherwise. |
+| GWF | SFR | DIVERSIONS | IFNO | INTEGER | integer value that defines the feature (reach) number associated with the specified DIVERSIONS data on the line. IFNO must be greater than zero and less than or equal to NREACHES.  Reach diversion information must be specified for every reach with a NDV value greater than 0 or the program will terminate with an error.  The program will also terminate with an error if diversion information for a given reach diversion is specified more than once. |
+| GWF | SFR | DIVERSIONS | IDV | INTEGER | integer value that defines the downstream diversion number for the diversion for reach IFNO. IDV must be greater than zero and less than or equal to NDV for reach IFNO. |
+| GWF | SFR | DIVERSIONS | ICONR | INTEGER | integer value that defines the downstream reach that will receive the diverted water. IDV must be greater than zero and less than or equal to NREACHES. Furthermore, reach  ICONR must be a downstream connection for reach IFNO. |
+| GWF | SFR | DIVERSIONS | CPRIOR | STRING | character string value that defines the the prioritization system for the diversion, such as when insufficient water is available to meet all diversion stipulations, and is used in conjunction with the value of FLOW value specified in the STRESS\_PERIOD\_DATA section. Available diversion options include:  (1) CPRIOR = `FRACTION', then the amount of the diversion is computed as a fraction of the streamflow leaving reach IFNO ($Q_{DS}$); in this case, 0.0 $\le$ DIVFLOW $\le$ 1.0.  (2) CPRIOR = `EXCESS', a diversion is made only if $Q_{DS}$ for reach IFNO exceeds the value of DIVFLOW. If this occurs, then the quantity of water diverted is the excess flow ($Q_{DS} -$ DIVFLOW) and $Q_{DS}$ from reach IFNO is set equal to DIVFLOW. This represents a flood-control type of diversion, as described by Danskin and Hanson (2002). (3) CPRIOR = `THRESHOLD', then if $Q_{DS}$ in reach IFNO is less than the specified diversion flow DIVFLOW, no water is diverted from reach IFNO. If $Q_{DS}$ in reach IFNO is greater than or equal to DIVFLOW, DIVFLOW is diverted and $Q_{DS}$ is set to the remainder ($Q_{DS} -$ DIVFLOW)). This approach assumes that once flow in the stream is sufficiently low, diversions from the stream cease, and is the `priority' algorithm that originally was programmed into the STR1 Package (Prudic, 1989).  (4) CPRIOR = `UPTO' -- if $Q_{DS}$ in reach IFNO is greater than or equal to the specified diversion flow DIVFLOW, $Q_{DS}$ is reduced by DIVFLOW. If $Q_{DS}$ in reach IFNO is less than DIVFLOW, DIVFLOW is set to $Q_{DS}$ and there will be no flow available for reaches connected to downstream end of reach IFNO. |
 | GWF | SFR | PERIOD | IPER | INTEGER | integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block. |
-| GWF | SFR | PERIOD | RNO | INTEGER | integer value that defines the reach number associated with the specified PERIOD data on the line. RNO must be greater than zero and less than or equal to NREACHES. |
+| GWF | SFR | PERIOD | IFNO | INTEGER | integer value that defines the feature (reach) number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NREACHES. |
 | GWF | SFR | PERIOD | SFRSETTING | KEYSTRING | line of information that is parsed into a keyword and values.  Keyword values that can be used to start the SFRSETTING string include: STATUS, MANNING, STAGE, INFLOW, RAINFALL, EVAPORATION, RUNOFF, DIVERSION, UPSTREAM\_FRACTION, and AUXILIARY. |
 | GWF | SFR | PERIOD | STATUS | STRING | keyword option to define stream reach status.  STATUS can be ACTIVE, INACTIVE, or SIMPLE. The SIMPLE STATUS option simulates streamflow using a user-specified stage for a reach or a stage set to the top of the reach (depth = 0). In cases where the simulated leakage calculated using the specified stage exceeds the sum of inflows to the reach, the stage is set to the top of the reach and leakage is set equal to the sum of inflows. Upstream fractions should be changed using the UPSTREAM\_FRACTION SFRSETTING if the status for one or more reaches is changed to ACTIVE or INACTIVE. For example, if one of two downstream connections for a reach is inactivated, the upstream fraction for the active and inactive downstream reach should be changed to 1.0 and 0.0, respectively, to ensure that the active reach receives all of the downstream outflow from the upstream reach. By default, STATUS is ACTIVE. |
 | GWF | SFR | PERIOD | MANNING | STRING | real or character value that defines the Manning's roughness coefficient for the reach. MANNING must be greater than zero.  If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
@@ -610,7 +612,7 @@
 | GWF | SFR | PERIOD | EVAPORATION | STRING | real or character value that defines the volumetric rate per unit area of water subtracted by evaporation from the streamflow routing reach. A positive evaporation rate should be provided. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. If the volumetric evaporation rate for a reach exceeds the sources of water to the reach (upstream and specified inflows, rainfall, and runoff but excluding groundwater leakage into the reach) the volumetric evaporation rate is limited to the sources of water to the reach. By default, evaporation rates are zero for each reach. |
 | GWF | SFR | PERIOD | RUNOFF | STRING | real or character value that defines the volumetric rate of diffuse overland runoff that enters the streamflow routing reach. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. If the volumetric runoff rate for a reach is negative and exceeds inflows to the reach (upstream and specified inflows, and rainfall but excluding groundwater leakage into the reach) the volumetric runoff rate is limited to inflows to the reach and the volumetric evaporation rate for the reach is set to zero. By default, runoff rates are zero for each reach. |
 | GWF | SFR | PERIOD | DIVERSION | KEYWORD | keyword to indicate diversion record. |
-| GWF | SFR | PERIOD | IDV | INTEGER | an integer value specifying which diversion of reach RNO that DIVFLOW is being specified for.  Must be less or equal to ndv for the current reach (RNO). |
+| GWF | SFR | PERIOD | IDV | INTEGER | an integer value specifying which diversion of reach IFNO that DIVFLOW is being specified for.  Must be less or equal to ndv for the current reach (IFNO). |
 | GWF | SFR | PERIOD | DIVFLOW | DOUBLE PRECISION | real or character value that defines the volumetric diversion (DIVFLOW) rate for the streamflow routing reach. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
 | GWF | SFR | PERIOD | UPSTREAM_FRACTION | DOUBLE PRECISION | real value that defines the fraction of upstream flow (USTRF) from each upstream reach that is applied as upstream inflow to the reach. The sum of all USTRF values for all reaches connected to the same upstream reach must be equal to one. |
 | GWF | SFR | PERIOD | CROSS_SECTION | KEYWORD | keyword to specify that record corresponds to a reach cross-section. |
@@ -649,21 +651,21 @@
 | GWF | LAK | DIMENSIONS | NLAKES | INTEGER | value specifying the number of lakes that will be simulated for all stress periods. |
 | GWF | LAK | DIMENSIONS | NOUTLETS | INTEGER | value specifying the number of outlets that will be simulated for all stress periods. If NOUTLETS is not specified, a default value of zero is used. |
 | GWF | LAK | DIMENSIONS | NTABLES | INTEGER | value specifying the number of lakes tables that will be used to define the lake stage, volume relation, and surface area. If NTABLES is not specified, a default value of zero is used. |
-| GWF | LAK | PACKAGEDATA | LAKENO | INTEGER | integer value that defines the lake number associated with the specified PACKAGEDATA data on the line. LAKENO must be greater than zero and less than or equal to NLAKES. Lake information must be specified for every lake or the program will terminate with an error.  The program will also terminate with an error if information for a lake is specified more than once. |
+| GWF | LAK | PACKAGEDATA | IFNO | INTEGER | integer value that defines the feature (lake) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NLAKES. Lake information must be specified for every lake or the program will terminate with an error.  The program will also terminate with an error if information for a lake is specified more than once. |
 | GWF | LAK | PACKAGEDATA | STRT | DOUBLE PRECISION | real value that defines the starting stage for the lake. |
-| GWF | LAK | PACKAGEDATA | NLAKECONN | INTEGER | integer value that defines the number of GWF cells connected to this (LAKENO) lake. There can only be one vertical lake connection to each GWF cell. NLAKECONN must be greater than zero. |
+| GWF | LAK | PACKAGEDATA | NLAKECONN | INTEGER | integer value that defines the number of GWF cells connected to this (IFNO) lake. There can only be one vertical lake connection to each GWF cell. NLAKECONN must be greater than zero. |
 | GWF | LAK | PACKAGEDATA | AUX | DOUBLE PRECISION (NAUX) | represents the values of the auxiliary variables for each lake. The values of auxiliary variables must be present for each lake. The values must be specified in the order of the auxiliary variables specified in the OPTIONS block.  If the package supports time series and the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
 | GWF | LAK | PACKAGEDATA | BOUNDNAME | STRING | name of the lake cell.  BOUNDNAME is an ASCII character variable that can contain as many as 40 characters.  If BOUNDNAME contains spaces in it, then the entire name must be enclosed within single quotes. |
-| GWF | LAK | CONNECTIONDATA | LAKENO | INTEGER | integer value that defines the lake number associated with the specified CONNECTIONDATA data on the line. LAKENO must be greater than zero and less than or equal to NLAKES. Lake connection information must be specified for every lake connection to the GWF model (NLAKECONN) or the program will terminate with an error.  The program will also terminate with an error if connection information for a lake connection to the GWF model is specified more than once. |
-| GWF | LAK | CONNECTIONDATA | ICONN | INTEGER | integer value that defines the GWF connection number for this lake connection entry. ICONN must be greater than zero and less than or equal to NLAKECONN for lake LAKENO. |
+| GWF | LAK | CONNECTIONDATA | IFNO | INTEGER | integer value that defines the feature (lake) number associated with the specified CONNECTIONDATA data on the line. IFNO must be greater than zero and less than or equal to NLAKES. Lake connection information must be specified for every lake connection to the GWF model (NLAKECONN) or the program will terminate with an error.  The program will also terminate with an error if connection information for a lake connection to the GWF model is specified more than once. |
+| GWF | LAK | CONNECTIONDATA | ICONN | INTEGER | integer value that defines the GWF connection number for this lake connection entry. ICONN must be greater than zero and less than or equal to NLAKECONN for lake IFNO. |
 | GWF | LAK | CONNECTIONDATA | CELLID | INTEGER (NCELLDIM) | is the cell identifier, and depends on the type of grid that is used for the simulation.  For a structured grid that uses the DIS input file, CELLID is the layer, row, and column.   For a grid that uses the DISV input file, CELLID is the layer and CELL2D number.  If the model uses the unstructured discretization (DISU) input file, CELLID is the node number for the cell. |
 | GWF | LAK | CONNECTIONDATA | CLAKTYPE | STRING | character string that defines the lake-GWF connection type for the lake connection. Possible lake-GWF connection type strings include:  VERTICAL--character keyword to indicate the lake-GWF connection is vertical  and connection conductance calculations use the hydraulic conductivity corresponding to the $K_{33}$ tensor component defined for CELLID in the NPF package. HORIZONTAL--character keyword to indicate the lake-GWF connection is horizontal and connection conductance calculations use the hydraulic conductivity corresponding to the $K_{11}$ tensor component defined for CELLID in the NPF package. EMBEDDEDH--character keyword to indicate the lake-GWF connection is embedded in a single cell and connection conductance calculations use the hydraulic conductivity corresponding to the $K_{11}$ tensor component defined for CELLID in the NPF package. EMBEDDEDV--character keyword to indicate the lake-GWF connection is embedded in a single cell and connection conductance calculations use the hydraulic conductivity corresponding to the $K_{33}$ tensor component defined for CELLID in the NPF package. Embedded lakes can only be connected to a single cell (NLAKECONN = 1) and there must be a lake table associated with each embedded lake. |
-| GWF | LAK | CONNECTIONDATA | BEDLEAK | STRING | character string or real value that defines the bed leakance for the lake-GWF connection. BEDLEAK must be greater than or equal to zero or specified to be NONE. If BEDLEAK is specified to be NONE, the lake-GWF connection conductance is solely a function of aquifer properties in the connected GWF cell and lakebed sediments are assumed to be absent. |
+| GWF | LAK | CONNECTIONDATA | BEDLEAK | STRING | real value or character string that defines the bed leakance for the lake-GWF connection. BEDLEAK must be greater than or equal to zero, equal to the DNODATA value (3.0E+30), or specified to be NONE. If DNODATA or NONE is specified for BEDLEAK, the lake-GWF connection conductance is solely a function of aquifer properties in the connected GWF cell and lakebed sediments are assumed to be absent. Warning messages will be issued if NONE is specified. Eventually the ability to specify NONE will be deprecated and cause MODFLOW 6 to terminate with an error. |
 | GWF | LAK | CONNECTIONDATA | BELEV | DOUBLE PRECISION | real value that defines the bottom elevation for a HORIZONTAL lake-GWF connection. Any value can be specified if CLAKTYPE is VERTICAL, EMBEDDEDH, or EMBEDDEDV. If CLAKTYPE is HORIZONTAL and BELEV is not equal to TELEV, BELEV must be greater than or equal to the bottom of the GWF cell CELLID. If BELEV is equal to TELEV, BELEV is reset to the bottom of the GWF cell CELLID. |
 | GWF | LAK | CONNECTIONDATA | TELEV | DOUBLE PRECISION | real value that defines the top elevation for a HORIZONTAL lake-GWF connection. Any value can be specified if CLAKTYPE is VERTICAL, EMBEDDEDH, or EMBEDDEDV. If CLAKTYPE is HORIZONTAL and TELEV is not equal to BELEV, TELEV must be less than or equal to the top of the GWF cell CELLID. If TELEV is equal to BELEV, TELEV is reset to the top of the GWF cell CELLID. |
 | GWF | LAK | CONNECTIONDATA | CONNLEN | DOUBLE PRECISION | real value that defines the distance between the connected GWF CELLID node and the lake for a HORIZONTAL, EMBEDDEDH, or EMBEDDEDV lake-GWF connection. CONLENN must be greater than zero for a HORIZONTAL, EMBEDDEDH, or EMBEDDEDV lake-GWF connection. Any value can be specified if CLAKTYPE is VERTICAL. |
 | GWF | LAK | CONNECTIONDATA | CONNWIDTH | DOUBLE PRECISION | real value that defines the connection face width for a HORIZONTAL lake-GWF connection. CONNWIDTH must be greater than zero for a HORIZONTAL lake-GWF connection. Any value can be specified if CLAKTYPE is VERTICAL, EMBEDDEDH, or EMBEDDEDV. |
-| GWF | LAK | TABLES | LAKENO | INTEGER | integer value that defines the lake number associated with the specified TABLES data on the line. LAKENO must be greater than zero and less than or equal to NLAKES. The program will terminate with an error if table information for a lake is specified more than once or the number of specified tables is less than NTABLES. |
+| GWF | LAK | TABLES | IFNO | INTEGER | integer value that defines the feature (lake) number associated with the specified TABLES data on the line. IFNO must be greater than zero and less than or equal to NLAKES. The program will terminate with an error if table information for a lake is specified more than once or the number of specified tables is less than NTABLES. |
 | GWF | LAK | TABLES | TAB6 | KEYWORD | keyword to specify that record corresponds to a table file. |
 | GWF | LAK | TABLES | FILEIN | KEYWORD | keyword to specify that an input filename is expected next. |
 | GWF | LAK | TABLES | TAB6_FILENAME | STRING | character string that defines the path and filename for the file containing lake table data for the lake connection. The TAB6\_FILENAME file includes the number of entries in the file and the relation between stage, volume, and surface area for each entry in the file. Lake table files for EMBEDDEDH and EMBEDDEDV lake-GWF connections also include lake-GWF exchange area data for each entry in the file. Instructions for creating the TAB6\_FILENAME input file are provided in Lake Table Input File section. |
@@ -685,7 +687,7 @@
 | GWF | LAK | PERIOD | RUNOFF | STRING | real or character value that defines the runoff rate $(L^3 T^{-1})$ for the lake. Value must be greater than or equal to zero. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
 | GWF | LAK | PERIOD | INFLOW | STRING | real or character value that defines the volumetric inflow rate $(L^3 T^{-1})$ for the lake. Value must be greater than or equal to zero. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. By default, inflow rates are zero for each lake. |
 | GWF | LAK | PERIOD | WITHDRAWAL | STRING | real or character value that defines the maximum withdrawal rate $(L^3 T^{-1})$ for the lake. Value must be greater than or equal to zero. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
-| GWF | LAK | PERIOD | RATE | STRING | real or character value that defines the extraction rate for the lake outflow. A positive value indicates inflow and a negative value indicates outflow from the lake. RATE only applies to active (IBOUND $>$ 0) lakes. A specified RATE is only applied if COUTTYPE for the OUTLETNO is SPECIFIED. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. By default, the RATE for each SPECIFIED lake outlet is zero. |
+| GWF | LAK | PERIOD | RATE | STRING | real or character value that defines the extraction rate for the lake outflow. A positive value indicates inflow and a negative value indicates outflow from the lake. RATE only applies to outlets associated with active lakes (STATUS is ACTIVE). A specified RATE is only applied if COUTTYPE for the OUTLETNO is SPECIFIED. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. By default, the RATE for each SPECIFIED lake outlet is zero. |
 | GWF | LAK | PERIOD | INVERT | STRING | real or character value that defines the invert elevation for the lake outlet. A specified INVERT value is only used for active lakes if COUTTYPE for lake outlet OUTLETNO is not SPECIFIED. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
 | GWF | LAK | PERIOD | ROUGH | STRING | real value that defines the roughness coefficient for the lake outlet. Any value can be specified if COUTTYPE is not MANNING. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
 | GWF | LAK | PERIOD | WIDTH | STRING | real or character value that defines the width of the lake outlet. A specified WIDTH value is only used for active lakes if COUTTYPE for lake outlet OUTLETNO is not SPECIFIED. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
@@ -723,7 +725,7 @@
 | GWF | UZF | DIMENSIONS | NUZFCELLS | INTEGER | is the number of UZF cells.  More than one UZF cell can be assigned to a GWF cell; however, only one GWF cell can be assigned to a single UZF cell. If more than one UZF cell is assigned to a GWF cell, then an auxiliary variable should be used to reduce the surface area of the UZF cell with the AUXMULTNAME option. |
 | GWF | UZF | DIMENSIONS | NTRAILWAVES | INTEGER | is the number of trailing waves.  A recommended value of 7 can be used for NTRAILWAVES.  This value can be increased to lower mass balance error in the unsaturated zone. |
 | GWF | UZF | DIMENSIONS | NWAVESETS | INTEGER | is the number of wave sets.  A recommended value of 40 can be used for NWAVESETS.  This value can be increased if more waves are required to resolve variations in water content within the unsaturated zone. |
-| GWF | UZF | PACKAGEDATA | IUZNO | INTEGER | integer value that defines the UZF cell number associated with the specified PACKAGEDATA data on the line. IUZNO must be greater than zero and less than or equal to NUZFCELLS.  UZF information must be specified for every UZF cell or the program will terminate with an error.  The program will also terminate with an error if information for a UZF cell is specified more than once. |
+| GWF | UZF | PACKAGEDATA | IFNO | INTEGER | integer value that defines the feature (UZF object) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NUZFCELLS.  UZF information must be specified for every UZF cell or the program will terminate with an error.  The program will also terminate with an error if information for a UZF cell is specified more than once. |
 | GWF | UZF | PACKAGEDATA | CELLID | INTEGER (NCELLDIM) | is the cell identifier, and depends on the type of grid that is used for the simulation.  For a structured grid that uses the DIS input file, CELLID is the layer, row, and column.   For a grid that uses the DISV input file, CELLID is the layer and CELL2D number.  If the model uses the unstructured discretization (DISU) input file, CELLID is the node number for the cell. |
 | GWF | UZF | PACKAGEDATA | LANDFLAG | INTEGER | integer value set to one for land surface cells indicating that boundary conditions can be applied and data can be specified in the PERIOD block. A value of 0 specifies a non-land surface cell. |
 | GWF | UZF | PACKAGEDATA | IVERTCON | INTEGER | integer value set to specify underlying UZF cell that receives water flowing to bottom of cell. If unsaturated zone flow reaches the water table before the cell bottom, then water is added to the GWF cell instead of flowing to the underlying UZF cell. A value of 0 indicates the UZF cell is not connected to an underlying UZF cell. |
@@ -735,7 +737,7 @@
 | GWF | UZF | PACKAGEDATA | EPS | DOUBLE PRECISION | is the exponent used in the Brooks-Corey function.  The Brooks-Corey function is used by UZF to calculated hydraulic conductivity under partially saturated conditions as a function of water content and the user-specified saturated hydraulic conductivity. |
 | GWF | UZF | PACKAGEDATA | BOUNDNAME | STRING | name of the UZF cell cell.  BOUNDNAME is an ASCII character variable that can contain as many as 40 characters.  If BOUNDNAME contains spaces in it, then the entire name must be enclosed within single quotes. |
 | GWF | UZF | PERIOD | IPER | INTEGER | integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block. |
-| GWF | UZF | PERIOD | IUZNO | INTEGER | integer value that defines the UZF cell number associated with the specified PERIOD data on the line. |
+| GWF | UZF | PERIOD | IFNO | INTEGER | integer value that defines the feature (UZF object) number associated with the specified PERIOD data on the line. |
 | GWF | UZF | PERIOD | FINF | STRING | real or character value that defines the applied infiltration rate of the UZF cell ($LT^{-1}$). If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
 | GWF | UZF | PERIOD | PET | STRING | real or character value that defines the potential evapotranspiration rate of the UZF cell and specified GWF cell. Evapotranspiration is first removed from the unsaturated zone and any remaining potential evapotranspiration is applied to the saturated zone. If IVERTCON is greater than zero then residual potential evapotranspiration not satisfied in the UZF cell is applied to the underlying UZF and GWF cells. PET is always specified, but is only used if SIMULATE\_ET is specified in the OPTIONS block. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
 | GWF | UZF | PERIOD | EXTDP | STRING | real or character value that defines the evapotranspiration extinction depth of the UZF cell. If IVERTCON is greater than zero and EXTDP extends below the GWF cell bottom then remaining potential evapotranspiration is applied to the underlying UZF and GWF cells. EXTDP is always specified, but is only used if SIMULATE\_ET is specified in the OPTIONS block. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
@@ -938,7 +940,7 @@
 | GWT | SSM | OPTIONS | PRINT_FLOWS | KEYWORD | keyword to indicate that the list of SSM flow rates will be printed to the listing file for every stress period time step in which ``BUDGET PRINT'' is specified in Output Control.  If there is no Output Control option and ``PRINT\_FLOWS'' is specified, then flow rates are printed for the last time step of each stress period. |
 | GWT | SSM | OPTIONS | SAVE_FLOWS | KEYWORD | keyword to indicate that SSM flow terms will be written to the file specified with ``BUDGET FILEOUT'' in Output Control. |
 | GWT | SSM | SOURCES | PNAME | STRING | name of the flow package for which an auxiliary variable contains a source concentration.  If this flow package is represented using an advanced transport package (SFT, LKT, MWT, or UZT), then the advanced transport package will override SSM terms specified here. |
-| GWT | SSM | SOURCES | SRCTYPE | STRING | keyword indicating how concentration will be assigned for sources and sinks.  Keyword must be specified as either AUX or AUXMIXED.  For both options the user must provide an auxiliary variable in the corresponding flow package.  The auxiliary variable must have the same name as the AUXNAME value that follows.  If the AUX keyword is specified, then the auxiliary variable specified by the user will be assigned as the concenration value for groundwater sources (flows with a positive sign).  For negative flow rates (sinks), groundwater will be withdrawn from the cell at the simulated concentration of the cell.  The AUXMIXED option provides an alternative method for how to determine the concentration of sinks.  If the cell concentration is larger than the user-specified auxiliary concentration, then the concentration of groundwater withdrawn from the cell will be assigned as the user-specified concentration.  Alternatively, if the user-specified auxiliary concentration is larger than the cell concentration, then groundwater will be withdrawn at the cell concentration.  Thus, the AUXMIXED option is designed to work with the Evapotranspiration (EVT) and Recharge (RCH) Packages where water may be withdrawn at a concentration that is less than the cell concentration. |
+| GWT | SSM | SOURCES | SRCTYPE | STRING | keyword indicating how concentration will be assigned for sources and sinks.  Keyword must be specified as either AUX or AUXMIXED.  For both options the user must provide an auxiliary variable in the corresponding flow package.  The auxiliary variable must have the same name as the AUXNAME value that follows.  If the AUX keyword is specified, then the auxiliary variable specified by the user will be assigned as the concentration value for groundwater sources (flows with a positive sign).  For negative flow rates (sinks), groundwater will be withdrawn from the cell at the simulated concentration of the cell.  The AUXMIXED option provides an alternative method for how to determine the concentration of sinks.  If the cell concentration is larger than the user-specified auxiliary concentration, then the concentration of groundwater withdrawn from the cell will be assigned as the user-specified concentration.  Alternatively, if the user-specified auxiliary concentration is larger than the cell concentration, then groundwater will be withdrawn at the cell concentration.  Thus, the AUXMIXED option is designed to work with the Evapotranspiration (EVT) and Recharge (RCH) Packages where water may be withdrawn at a concentration that is less than the cell concentration. |
 | GWT | SSM | SOURCES | AUXNAME | STRING | name of the auxiliary variable in the package PNAME.  This auxiliary variable must exist and be specified by the user in that package.  The values in this auxiliary variable will be used to set the concentration associated with the flows for that boundary package. |
 | GWT | SSM | FILEINPUT | PNAME | STRING | name of the flow package for which an SPC6 input file contains a source concentration.  If this flow package is represented using an advanced transport package (SFT, LKT, MWT, or UZT), then the advanced transport package will override SSM terms specified here. |
 | GWT | SSM | FILEINPUT | SPC6 | KEYWORD | keyword to specify that record corresponds to a source sink mixing input file. |
@@ -1016,12 +1018,12 @@
 | GWT | SFT | OPTIONS | TS6_FILENAME | STRING | defines a time-series file defining time series that can be used to assign time-varying values. See the ``Time-Variable Input'' section for instructions on using the time-series capability. |
 | GWT | SFT | OPTIONS | OBS6 | KEYWORD | keyword to specify that record corresponds to an observations file. |
 | GWT | SFT | OPTIONS | OBS6_FILENAME | STRING | name of input file to define observations for the SFT package. See the ``Observation utility'' section for instructions for preparing observation input files. Tables \ref{table:gwf-obstypetable} and \ref{table:gwt-obstypetable} lists observation type(s) supported by the SFT package. |
-| GWT | SFT | PACKAGEDATA | RNO | INTEGER | integer value that defines the reach number associated with the specified PACKAGEDATA data on the line. RNO must be greater than zero and less than or equal to NREACHES. Reach information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if information for a reach is specified more than once. |
+| GWT | SFT | PACKAGEDATA | IFNO | INTEGER | integer value that defines the feature (reach) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NREACHES. Reach information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if information for a reach is specified more than once. |
 | GWT | SFT | PACKAGEDATA | STRT | DOUBLE PRECISION | real value that defines the starting concentration for the reach. |
 | GWT | SFT | PACKAGEDATA | AUX | DOUBLE PRECISION (NAUX) | represents the values of the auxiliary variables for each reach. The values of auxiliary variables must be present for each reach. The values must be specified in the order of the auxiliary variables specified in the OPTIONS block.  If the package supports time series and the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
 | GWT | SFT | PACKAGEDATA | BOUNDNAME | STRING | name of the reach cell.  BOUNDNAME is an ASCII character variable that can contain as many as 40 characters.  If BOUNDNAME contains spaces in it, then the entire name must be enclosed within single quotes. |
 | GWT | SFT | PERIOD | IPER | INTEGER | integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block. |
-| GWT | SFT | PERIOD | RNO | INTEGER | integer value that defines the reach number associated with the specified PERIOD data on the line. RNO must be greater than zero and less than or equal to NREACHES. |
+| GWT | SFT | PERIOD | IFNO | INTEGER | integer value that defines the feature (reach) number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NREACHES. |
 | GWT | SFT | PERIOD | REACHSETTING | KEYSTRING | line of information that is parsed into a keyword and values.  Keyword values that can be used to start the REACHSETTING string include: STATUS, CONCENTRATION, RAINFALL, EVAPORATION, RUNOFF, and AUXILIARY.  These settings are used to assign the concentration of associated with the corresponding flow terms.  Concentrations cannot be specified for all flow terms.  For example, the Streamflow Package supports a ``DIVERSION'' flow term.  Diversion water will be routed using the calculated concentration of the reach. |
 | GWT | SFT | PERIOD | STATUS | STRING | keyword option to define reach status.  STATUS can be ACTIVE, INACTIVE, or CONSTANT. By default, STATUS is ACTIVE, which means that concentration will be calculated for the reach.  If a reach is inactive, then there will be no solute mass fluxes into or out of the reach and the inactive value will be written for the reach concentration.  If a reach is constant, then the concentration for the reach will be fixed at the user specified value. |
 | GWT | SFT | PERIOD | CONCENTRATION | STRING | real or character value that defines the concentration for the reach. The specified CONCENTRATION is only applied if the reach is a constant concentration reach. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
@@ -1052,13 +1054,13 @@
 | GWT | LKT | OPTIONS | TS6_FILENAME | STRING | defines a time-series file defining time series that can be used to assign time-varying values. See the ``Time-Variable Input'' section for instructions on using the time-series capability. |
 | GWT | LKT | OPTIONS | OBS6 | KEYWORD | keyword to specify that record corresponds to an observations file. |
 | GWT | LKT | OPTIONS | OBS6_FILENAME | STRING | name of input file to define observations for the LKT package. See the ``Observation utility'' section for instructions for preparing observation input files. Tables \ref{table:gwf-obstypetable} and \ref{table:gwt-obstypetable} lists observation type(s) supported by the LKT package. |
-| GWT | LKT | PACKAGEDATA | LAKENO | INTEGER | integer value that defines the lake number associated with the specified PACKAGEDATA data on the line. LAKENO must be greater than zero and less than or equal to NLAKES. Lake information must be specified for every lake or the program will terminate with an error.  The program will also terminate with an error if information for a lake is specified more than once. |
+| GWT | LKT | PACKAGEDATA | IFNO | INTEGER | integer value that defines the feature (lake) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NLAKES. Lake information must be specified for every lake or the program will terminate with an error.  The program will also terminate with an error if information for a lake is specified more than once. |
 | GWT | LKT | PACKAGEDATA | STRT | DOUBLE PRECISION | real value that defines the starting concentration for the lake. |
 | GWT | LKT | PACKAGEDATA | AUX | DOUBLE PRECISION (NAUX) | represents the values of the auxiliary variables for each lake. The values of auxiliary variables must be present for each lake. The values must be specified in the order of the auxiliary variables specified in the OPTIONS block.  If the package supports time series and the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
 | GWT | LKT | PACKAGEDATA | BOUNDNAME | STRING | name of the lake cell.  BOUNDNAME is an ASCII character variable that can contain as many as 40 characters.  If BOUNDNAME contains spaces in it, then the entire name must be enclosed within single quotes. |
 | GWT | LKT | PERIOD | IPER | INTEGER | integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block. |
-| GWT | LKT | PERIOD | LAKENO | INTEGER | integer value that defines the lake number associated with the specified PERIOD data on the line. LAKENO must be greater than zero and less than or equal to NLAKES. |
-| GWT | LKT | PERIOD | LAKSETTING | KEYSTRING | line of information that is parsed into a keyword and values.  Keyword values that can be used to start the LAKSETTING string include: STATUS, CONCENTRATION, RAINFALL, EVAPORATION, RUNOFF, and AUXILIARY.  These settings are used to assign the concentration of associated with the corresponding flow terms.  Concentrations cannot be specified for all flow terms.  For example, the Lake Package supports a ``WITHDRAWAL'' flow term.  If this withdrawal term is active, then water will be withdrawn from the lake at the calculated concentration of the lake. |
+| GWT | LKT | PERIOD | IFNO | INTEGER | integer value that defines the feature (lake) number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NLAKES. |
+| GWT | LKT | PERIOD | LAKSETTING | KEYSTRING | line of information that is parsed into a keyword and values.  Keyword values that can be used to start the LAKSETTING string include: STATUS, CONCENTRATION, RAINFALL, EVAPORATION, RUNOFF, EXT-INFLOW, and AUXILIARY.  These settings are used to assign the concentration of associated with the corresponding flow terms.  Concentrations cannot be specified for all flow terms.  For example, the Lake Package supports a ``WITHDRAWAL'' flow term.  If this withdrawal term is active, then water will be withdrawn from the lake at the calculated concentration of the lake. |
 | GWT | LKT | PERIOD | STATUS | STRING | keyword option to define lake status.  STATUS can be ACTIVE, INACTIVE, or CONSTANT. By default, STATUS is ACTIVE, which means that concentration will be calculated for the lake.  If a lake is inactive, then there will be no solute mass fluxes into or out of the lake and the inactive value will be written for the lake concentration.  If a lake is constant, then the concentration for the lake will be fixed at the user specified value. |
 | GWT | LKT | PERIOD | CONCENTRATION | STRING | real or character value that defines the concentration for the lake. The specified CONCENTRATION is only applied if the lake is a constant concentration lake. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
 | GWT | LKT | PERIOD | RAINFALL | STRING | real or character value that defines the rainfall solute concentration $(ML^{-3})$ for the lake. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
@@ -1088,13 +1090,13 @@
 | GWT | MWT | OPTIONS | TS6_FILENAME | STRING | defines a time-series file defining time series that can be used to assign time-varying values. See the ``Time-Variable Input'' section for instructions on using the time-series capability. |
 | GWT | MWT | OPTIONS | OBS6 | KEYWORD | keyword to specify that record corresponds to an observations file. |
 | GWT | MWT | OPTIONS | OBS6_FILENAME | STRING | name of input file to define observations for the MWT package. See the ``Observation utility'' section for instructions for preparing observation input files. Tables \ref{table:gwf-obstypetable} and \ref{table:gwt-obstypetable} lists observation type(s) supported by the MWT package. |
-| GWT | MWT | PACKAGEDATA | MAWNO | INTEGER | integer value that defines the well number associated with the specified PACKAGEDATA data on the line. MAWNO must be greater than zero and less than or equal to NMAWWELLS. Well information must be specified for every well or the program will terminate with an error.  The program will also terminate with an error if information for a well is specified more than once. |
+| GWT | MWT | PACKAGEDATA | IFNO | INTEGER | integer value that defines the feature (well) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NMAWWELLS. Well information must be specified for every well or the program will terminate with an error.  The program will also terminate with an error if information for a well is specified more than once. |
 | GWT | MWT | PACKAGEDATA | STRT | DOUBLE PRECISION | real value that defines the starting concentration for the well. |
 | GWT | MWT | PACKAGEDATA | AUX | DOUBLE PRECISION (NAUX) | represents the values of the auxiliary variables for each well. The values of auxiliary variables must be present for each well. The values must be specified in the order of the auxiliary variables specified in the OPTIONS block.  If the package supports time series and the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
 | GWT | MWT | PACKAGEDATA | BOUNDNAME | STRING | name of the well cell.  BOUNDNAME is an ASCII character variable that can contain as many as 40 characters.  If BOUNDNAME contains spaces in it, then the entire name must be enclosed within single quotes. |
 | GWT | MWT | PERIOD | IPER | INTEGER | integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block. |
-| GWT | MWT | PERIOD | MAWNO | INTEGER | integer value that defines the well number associated with the specified PERIOD data on the line. MAWNO must be greater than zero and less than or equal to NMAWWELLS. |
-| GWT | MWT | PERIOD | MWTSETTING | KEYSTRING | line of information that is parsed into a keyword and values.  Keyword values that can be used to start the MWTSETTING string include: STATUS, CONCENTRATION, RAINFALL, EVAPORATION, RUNOFF, and AUXILIARY.  These settings are used to assign the concentration of associated with the corresponding flow terms.  Concentrations cannot be specified for all flow terms.  For example, the Multi-Aquifer Well Package supports a ``WITHDRAWAL'' flow term.  If this withdrawal term is active, then water will be withdrawn from the well at the calculated concentration of the well. |
+| GWT | MWT | PERIOD | IFNO | INTEGER | integer value that defines the feature (well) number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NMAWWELLS. |
+| GWT | MWT | PERIOD | MWTSETTING | KEYSTRING | line of information that is parsed into a keyword and values.  Keyword values that can be used to start the MWTSETTING string include: STATUS, CONCENTRATION, RATE, and AUXILIARY.  These settings are used to assign the concentration associated with the corresponding flow terms.  Concentrations cannot be specified for all flow terms.  For example, the Multi-Aquifer Well Package supports a ``WITHDRAWAL'' flow term.  If this withdrawal term is active, then water will be withdrawn from the well at the calculated concentration of the well. |
 | GWT | MWT | PERIOD | STATUS | STRING | keyword option to define well status.  STATUS can be ACTIVE, INACTIVE, or CONSTANT. By default, STATUS is ACTIVE, which means that concentration will be calculated for the well.  If a well is inactive, then there will be no solute mass fluxes into or out of the well and the inactive value will be written for the well concentration.  If a well is constant, then the concentration for the well will be fixed at the user specified value. |
 | GWT | MWT | PERIOD | CONCENTRATION | STRING | real or character value that defines the concentration for the well. The specified CONCENTRATION is only applied if the well is a constant concentration well. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
 | GWT | MWT | PERIOD | RATE | STRING | real or character value that defines the injection solute concentration $(ML^{-3})$ for the well. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
@@ -1121,12 +1123,12 @@
 | GWT | UZT | OPTIONS | TS6_FILENAME | STRING | defines a time-series file defining time series that can be used to assign time-varying values. See the ``Time-Variable Input'' section for instructions on using the time-series capability. |
 | GWT | UZT | OPTIONS | OBS6 | KEYWORD | keyword to specify that record corresponds to an observations file. |
 | GWT | UZT | OPTIONS | OBS6_FILENAME | STRING | name of input file to define observations for the UZT package. See the ``Observation utility'' section for instructions for preparing observation input files. Tables \ref{table:gwf-obstypetable} and \ref{table:gwt-obstypetable} lists observation type(s) supported by the UZT package. |
-| GWT | UZT | PACKAGEDATA | UZFNO | INTEGER | integer value that defines the UZF cell number associated with the specified PACKAGEDATA data on the line. UZFNO must be greater than zero and less than or equal to NUZFCELLS. Unsaturated zone flow information must be specified for every UZF cell or the program will terminate with an error.  The program will also terminate with an error if information for a UZF cell is specified more than once. |
+| GWT | UZT | PACKAGEDATA | IFNO | INTEGER | integer value that defines the feature (UZF object) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NUZFCELLS. Unsaturated zone flow information must be specified for every UZF cell or the program will terminate with an error.  The program will also terminate with an error if information for a UZF cell is specified more than once. |
 | GWT | UZT | PACKAGEDATA | STRT | DOUBLE PRECISION | real value that defines the starting concentration for the unsaturated zone flow cell. |
 | GWT | UZT | PACKAGEDATA | AUX | DOUBLE PRECISION (NAUX) | represents the values of the auxiliary variables for each unsaturated zone flow. The values of auxiliary variables must be present for each unsaturated zone flow. The values must be specified in the order of the auxiliary variables specified in the OPTIONS block.  If the package supports time series and the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
 | GWT | UZT | PACKAGEDATA | BOUNDNAME | STRING | name of the unsaturated zone flow cell.  BOUNDNAME is an ASCII character variable that can contain as many as 40 characters.  If BOUNDNAME contains spaces in it, then the entire name must be enclosed within single quotes. |
 | GWT | UZT | PERIOD | IPER | INTEGER | integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block. |
-| GWT | UZT | PERIOD | UZFNO | INTEGER | integer value that defines the UZF cell number associated with the specified PERIOD data on the line. UZFNO must be greater than zero and less than or equal to NUZFCELLS. |
+| GWT | UZT | PERIOD | IFNO | INTEGER | integer value that defines the feature (UZF object) number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NUZFCELLS. |
 | GWT | UZT | PERIOD | UZTSETTING | KEYSTRING | line of information that is parsed into a keyword and values.  Keyword values that can be used to start the UZTSETTING string include: STATUS, CONCENTRATION, INFILTRATION, UZET, and AUXILIARY.  These settings are used to assign the concentration of associated with the corresponding flow terms.  Concentrations cannot be specified for all flow terms. |
 | GWT | UZT | PERIOD | STATUS | STRING | keyword option to define UZF cell status.  STATUS can be ACTIVE, INACTIVE, or CONSTANT. By default, STATUS is ACTIVE, which means that concentration will be calculated for the UZF cell.  If a UZF cell is inactive, then there will be no solute mass fluxes into or out of the UZF cell and the inactive value will be written for the UZF cell concentration.  If a UZF cell is constant, then the concentration for the UZF cell will be fixed at the user specified value. |
 | GWT | UZT | PERIOD | CONCENTRATION | STRING | real or character value that defines the concentration for the unsaturated zone flow cell. The specified CONCENTRATION is only applied if the unsaturated zone flow cell is a constant concentration cell. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. |
@@ -1164,7 +1166,7 @@
 | UTL | SPC | DIMENSIONS | MAXBOUND | INTEGER | integer value specifying the maximum number of spc cells that will be specified for use during any stress period. |
 | UTL | SPC | PERIOD | IPER | INTEGER | integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block. |
 | UTL | SPC | PERIOD | BNDNO | INTEGER | integer value that defines the boundary package feature number associated with the specified PERIOD data on the line. BNDNO must be greater than zero and less than or equal to MAXBOUND. |
-| UTL | SPC | PERIOD | SPCSETTING | KEYSTRING | line of information that is parsed into a keyword and values.  Keyword values that can be used to start the MAWSETTING string include: CONCENTRATION. |
+| UTL | SPC | PERIOD | SPCSETTING | KEYSTRING | line of information that is parsed into a keyword and values.  Keyword values that can be used to start the SPCSETTING string include: CONCENTRATION. |
 | UTL | SPC | PERIOD | CONCENTRATION | DOUBLE PRECISION | is the boundary concentration. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. By default, the CONCENTRATION for each boundary feature is zero. |
 | UTL | SPCA | OPTIONS | READASARRAYS | KEYWORD | indicates that array-based input will be used for the SPC Package.  This keyword must be specified to use array-based input. |
 | UTL | SPCA | OPTIONS | PRINT_INPUT | KEYWORD | keyword to indicate that the list of spc information will be written to the listing file immediately after it is read. |
diff --git a/doc/mf6io/mf6ivar/mf6ivar.py b/doc/mf6io/mf6ivar/mf6ivar.py
index 4d81cdd52f0..27684de1ada 100644
--- a/doc/mf6io/mf6ivar/mf6ivar.py
+++ b/doc/mf6io/mf6ivar/mf6ivar.py
@@ -129,10 +129,14 @@
 
 
 import os
+from pathlib import Path
 import sys
 from collections import OrderedDict
 import re
 import shutil
+from tempfile import TemporaryDirectory
+from typing import Dict, List, Optional, Tuple
+from packaging.version import Version
 
 VERBOSE = False
 for arg in sys.argv:
@@ -360,6 +364,9 @@ def write_desc(vardict, block, blk_var_list, varexcludeprefix=None):
             if 'deprecated' in v:
                 if v['deprecated'] != '':
                     addv = False
+            if 'removed' in v:
+                if v['removed'] != '':
+                    addv = False
             if addv:
                 if v['type'] == 'keyword':
                     n = name.upper()
@@ -419,6 +426,9 @@ def write_desc_md(vardict, block, blk_var_list, varexcludeprefix=None):
             if 'deprecated' in v:
                 if v['deprecated'] != '':
                     addv = False
+            if 'removed' in v:
+                if v['removed'] != '':
+                    addv = False
             if addv:
                 if v['type'] == 'keyword':
                     n = name.upper()
@@ -603,54 +613,48 @@ def write_md(f, vardict, component, package):
 
 def write_appendix(texdir, allblocks):
     fname = os.path.join(texdir, 'appendixA.tex')
-    f = open(fname, 'w')
-    f.write('\\small\n\\begin{longtable}{p{1.5cm} p{1.5cm} p{3cm} c}\n')
-    f.write(
-        '\\caption{List of block names organized by component and input file '
-        'type.  OPEN/CLOSE indicates whether or not the block information '
-        'can be contained in separate file} \\tabularnewline \n\n')
-    # f.write(
-    #    '\\caption{List of all possible blocks} \\tabularnewline \n\\endfirsthead \n\n')
-    # f.write(
-    #    '\\caption*{List of all possible blocks} \\tabularnewline\n\n')
-    f.write('\\hline\n\\hline\n')
-    f.write(
-        '\\textbf{Component} & \\textbf{FTYPE} & \\textbf{Blockname} & \\textbf{OPEN/CLOSE} \\\\\n')
-    f.write('\\hline\n\\endfirsthead\n\n\n')
-
-    f.write('\captionsetup{textformat=simple}\n')
-    f.write('\caption*{\\textbf{Table A--\\arabic{table}.}{\quad}List of block'
-            ' names organized by component and input file type.  OPEN/CLOSE '
-            'indicates whether or not the block information can be contained '
-            'in separate file.---Continued} \\tabularnewline\n')
-
-    f.write('\n\\hline\n\\hline\n')
-    f.write(
-        '\\textbf{Component} & \\textbf{FTYPE} & \\textbf{Blockname} & \\textbf{OPEN/CLOSE} \\\\\n')
-    f.write('\\hline\n\\endhead\n\n\\hline\n\\endfoot\n\n\n')
-
-    lastftype = ''
-    for b in allblocks:
-        l = b.strip().split('-')
-        component, ftype, blockname = l
-        if lastftype != ftype:
-            f.write('\\hline\n')
-        oc = 'yes'
-        if 'griddata' in blockname.lower():
-            oc = 'no'
-        if 'utl' in component.lower() and \
-                'tas' in ftype.lower() and 'time' in blockname.lower():
-            oc = 'no'
-        s = '{} & {} & {} & {} \\\\ \n'.format(component.upper(),
-                                               ftype.upper(),
-                                               blockname.upper(), oc)
-        f.write(s)
-        lastftype = ftype
+    with open(fname, 'w') as f:
+        f.write('\\small\n\\begin{longtable}{p{1.5cm} p{1.5cm} p{3cm} c}\n')
+        f.write(
+            '\\caption{List of block names organized by component and input file '
+            'type.  OPEN/CLOSE indicates whether or not the block information '
+            'can be contained in separate file} \\tabularnewline \n\n')
+        f.write('\\hline\n\\hline\n')
+        f.write(
+            '\\textbf{Component} & \\textbf{FTYPE} & \\textbf{Blockname} & \\textbf{OPEN/CLOSE} \\\\\n')
+        f.write('\\hline\n\\endfirsthead\n\n\n')
+
+        f.write('\captionsetup{textformat=simple}\n')
+        f.write('\caption*{\\textbf{Table A--\\arabic{table}.}{\quad}List of block'
+                ' names organized by component and input file type.  OPEN/CLOSE '
+                'indicates whether or not the block information can be contained '
+                'in separate file.---Continued} \\tabularnewline\n')
+
+        f.write('\n\\hline\n\\hline\n')
+        f.write(
+            '\\textbf{Component} & \\textbf{FTYPE} & \\textbf{Blockname} & \\textbf{OPEN/CLOSE} \\\\\n')
+        f.write('\\hline\n\\endhead\n\n\\hline\n\\endfoot\n\n\n')
+
+        lastftype = ''
+        for b in allblocks:
+            l = b.strip().split('-')
+            component, ftype, blockname = l
+            if lastftype != ftype:
+                f.write('\\hline\n')
+            oc = 'yes'
+            if 'griddata' in blockname.lower():
+                oc = 'no'
+            if 'utl' in component.lower() and \
+                    'tas' in ftype.lower() and 'time' in blockname.lower():
+                oc = 'no'
+            s = '{} & {} & {} & {} \\\\ \n'.format(component.upper(),
+                                                ftype.upper(),
+                                                blockname.upper(), oc)
+            f.write(s)
+            lastftype = ftype
 
-    f.write(
-        '\n\n\\hline\n\\end{longtable}\n\\label{table:blocks}\n\\normalsize\n')
-    f.close()
-    return
+        f.write(
+            '\n\n\\hline\n\\end{longtable}\n\\label{table:blocks}\n\\normalsize\n')
 
 
 if __name__ == '__main__':
@@ -737,142 +741,141 @@ def write_appendix(texdir, allblocks):
 
     # setup a markdown file
     fname = os.path.join(mddir, 'mf6ivar.md')
-    fmd = open(fname, 'w')
-    write_md_header(fmd)
+    with open(fname, 'w') as fmd:
+        write_md_header(fmd)
+
+        # construct list of dfn files to process in the order of file_order
+        files = os.listdir(dfndir)
+        for f in files:
+            if 'common' in f:
+                continue
+            if '.DS_Store' in f:
+                continue
+            if os.path.splitext(f)[0] not in file_order:
+                raise Exception('File not in file_order: ', f)
+        files = [fname + '.dfn' for fname in file_order if fname + '.dfn' in files]
+        # files = ['gwf-obs.dfn']
+
+        # # create rst file for markdown
+        # fpth = os.path.join(docdir, "mf6io.rst")
+        # frst = open(fpth, "w")
+        # s =  ".. toctree::\n"
+        # s += "   :maxdepth: 4\n"
+        # s += "   :name: mf6-io\n\n"
+        # frst.write(s)
 
-    # construct list of dfn files to process in the order of file_order
-    files = os.listdir(dfndir)
-    for f in files:
-        if 'common' in f:
-            continue
-        if '.DS_Store' in f:
-            continue
-        if os.path.splitext(f)[0] not in file_order:
-            raise Exception('File not in file_order: ', f)
-    files = [fname + '.dfn' for fname in file_order if fname + '.dfn' in files]
-    # files = ['gwf-obs.dfn']
-
-    # # create rst file for markdown
-    # fpth = os.path.join(docdir, "mf6io.rst")
-    # frst = open(fpth, "w")
-    # s =  ".. toctree::\n"
-    # s += "   :maxdepth: 4\n"
-    # s += "   :name: mf6-io\n\n"
-    # frst.write(s)
-
-    for txtname in files:
-        component, package = os.path.splitext(txtname)[0].split('-')[0:2]
-        vardict = parse_mf6var_file(os.path.join(dfndir, txtname))
-
-        # make list of unique block names
-        blocks = []
-        for k in vardict:
-            v = vardict[k]
-            b = v['block']
-            if b not in blocks:
-                blocks.append(b)
-
-        # add a full block name to allblocks
-        for block in blocks:
-            b = '{}-{}-{}'.format(component, package, block)
-            allblocks.append(b)
-
-        # go through each block and write information
-        desc = '% DO NOT MODIFY THIS FILE DIRECTLY.  IT IS CREATED BY mf6ivar.py \n\n'
-        for b in blocks:
-            blk_var_list = []
-
-            # Write the name of the block to the latex file
-            desc += '\item \\textbf{}\n\n'.format('{Block: ' + b.upper() + '}')
-
-            desc += '\\begin{description}\n'
-            desc += write_desc(vardict, b, blk_var_list,
-                               varexcludeprefix='dev_')
-            desc += '\\end{description}\n'
-
-            fname = os.path.join(texdir, os.path.splitext(txtname)[
-                0] + '-' + b + '.dat')
+        for txtname in files:
+            component, package = os.path.splitext(txtname)[0].split('-')[0:2]
+            vardict = parse_mf6var_file(os.path.join(dfndir, txtname))
+
+            # make list of unique block names
+            blocks = []
+            for k in vardict:
+                v = vardict[k]
+                b = v['block']
+                if b not in blocks:
+                    blocks.append(b)
+
+            # add a full block name to allblocks
+            for block in blocks:
+                b = '{}-{}-{}'.format(component, package, block)
+                allblocks.append(b)
+
+            # go through each block and write information
+            desc = '% DO NOT MODIFY THIS FILE DIRECTLY.  IT IS CREATED BY mf6ivar.py \n\n'
+            for b in blocks:
+                blk_var_list = []
+
+                # Write the name of the block to the latex file
+                desc += '\item \\textbf{}\n\n'.format('{Block: ' + b.upper() + '}')
+
+                desc += '\\begin{description}\n'
+                desc += write_desc(vardict, b, blk_var_list,
+                                varexcludeprefix='dev_')
+                desc += '\\end{description}\n'
+
+                fname = os.path.join(texdir, os.path.splitext(txtname)[
+                    0] + '-' + b + '.dat')
+                f = open(fname, 'w')
+                s = write_block(vardict, b, blk_var_list,
+                                varexcludeprefix='dev_') + '\n'
+                f.write(s)
+                if VERBOSE:
+                    print(s)
+                f.close()
+            fname = os.path.join(texdir,
+                                os.path.splitext(txtname)[0] + '-desc' + '.tex')
             f = open(fname, 'w')
-            s = write_block(vardict, b, blk_var_list,
-                            varexcludeprefix='dev_') + '\n'
+            s = desc + '\n'
             f.write(s)
             if VERBOSE:
                 print(s)
             f.close()
-        fname = os.path.join(texdir,
-                             os.path.splitext(txtname)[0] + '-desc' + '.tex')
-        f = open(fname, 'w')
-        s = desc + '\n'
-        f.write(s)
-        if VERBOSE:
-            print(s)
-        f.close()
-
-        # write markdown description
-        mdname = os.path.splitext(txtname)[0]
-        fname = os.path.join(docdir, mdname + '.md')
-        f = open(fname, 'w')
-        f.write("### {}\n\n".format(mdname.upper()))
-        f.write("#### Structure of Blocks\n\n")
-        f.write("_FOR EACH SIMULATION_\n\n")
-        desc = ""
-        for b in blocks:
-            blk_var_list = []
-
-            # Write the name of the block to the latex file
-            desc += '##### Block: {}\n\n'.format(b.upper())
-
-            desc += write_desc_md(vardict, b, blk_var_list,
-                                  varexcludeprefix='dev_')
-
-            if "period" in b.lower():
-                f.write("\n_FOR ANY STRESS PERIOD_\n\n")
-            f.write("```\n")
-            s = md_replace(write_block(vardict, b, blk_var_list,
-                                       varexcludeprefix='dev_',
-                                       indent=4)) + "\n"
-            # s = s.replace("@", "") + "\n"
-            f.write(s)
-            f.write("```\n")
-            if VERBOSE:
-                print(s)
-
-        f.write("\n#### Explanation of Variables\n\n")
-        f.write(desc)
-
-        # add examples
-        s = get_examples(mdname)
-        if len(s) > 0:
-            f.write(s)
 
-        # add observation table
-        s = get_obs_table(mdname)
-        if len(s) > 0:
-            f.write(s)
-
-        # add observation examples
-        s = get_obs_examples(mdname)
-        if len(s) > 0:
-            f.write(s)
-
-        # close the markdown file
-        f.close()
+            # write markdown description
+            mdname = os.path.splitext(txtname)[0]
+            fname = os.path.join(docdir, mdname + '.md')
+            f = open(fname, 'w')
+            f.write("### {}\n\n".format(mdname.upper()))
+            f.write("#### Structure of Blocks\n\n")
+            f.write("_FOR EACH SIMULATION_\n\n")
+            desc = ""
+            for b in blocks:
+                blk_var_list = []
+
+                # Write the name of the block to the latex file
+                desc += '##### Block: {}\n\n'.format(b.upper())
+
+                desc += write_desc_md(vardict, b, blk_var_list,
+                                    varexcludeprefix='dev_')
+
+                if "period" in b.lower():
+                    f.write("\n_FOR ANY STRESS PERIOD_\n\n")
+                f.write("```\n")
+                s = md_replace(write_block(vardict, b, blk_var_list,
+                                        varexcludeprefix='dev_',
+                                        indent=4)) + "\n"
+                # s = s.replace("@", "") + "\n"
+                f.write(s)
+                f.write("```\n")
+                if VERBOSE:
+                    print(s)
+
+            f.write("\n#### Explanation of Variables\n\n")
+            f.write(desc)
+
+            # add examples
+            s = get_examples(mdname)
+            if len(s) > 0:
+                f.write(s)
+
+            # add observation table
+            s = get_obs_table(mdname)
+            if len(s) > 0:
+                f.write(s)
+
+            # add observation examples
+            s = get_obs_examples(mdname)
+            if len(s) > 0:
+                f.write(s)
+
+            # close the markdown file
+            f.close()
 
-        # # add to rst catalog
-        # s = "   {}\n".format(os.path.basename(fname))
-        # frst.write(s)
+            # # add to rst catalog
+            # s = "   {}\n".format(os.path.basename(fname))
+            # frst.write(s)
 
-        # write markdown
-        write_md(fmd, vardict, component, package)
+            # write markdown
+            write_md(fmd, vardict, component, package)
 
-    # # close restart catalog
-    # frst.write("\n\n")
-    # frst.close()
+        # # close restart catalog
+        # frst.write("\n\n")
+        # frst.close()
 
-    if VERBOSE:
-        for b in allblocks:
-            print(b)
-    write_appendix(texdir, allblocks)
+        if VERBOSE:
+            for b in allblocks:
+                print(b)
+        write_appendix(texdir, allblocks)
 
-    # markdown close
-    fmd.close()
+    
diff --git a/doc/mf6io/mf6ivar/readme.md b/doc/mf6io/mf6ivar/readme.md
index 3a78c3273fa..f373fffc9dc 100644
--- a/doc/mf6io/mf6ivar/readme.md
+++ b/doc/mf6io/mf6ivar/readme.md
@@ -693,3 +693,5 @@ In the description attribute, the capital REPLACE instructs the processor to rep
 The Python script [mf6ivar.py](mf6ivar.py) will process all of the definition files and create a markdown file, latex files of the variable descriptions, and text files containing the blocks.
 
 
+# Deprecations
+The Python script [deprecations.py](deprecations.py) will search definition files for `deprecated` or `removed` options and create a markdown file containing a table of deprecations and removals.
\ No newline at end of file
diff --git a/doc/mf6io/mf6ivar/tex/gwf-disu-cell2d.dat b/doc/mf6io/mf6ivar/tex/gwf-disu-cell2d.dat
index 27900d67235..f6d08961367 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-disu-cell2d.dat
+++ b/doc/mf6io/mf6ivar/tex/gwf-disu-cell2d.dat
@@ -1,5 +1,5 @@
 BEGIN CELL2D
+  [<icell2d> <xc> <yc> <ncvert> <icvert(ncvert)>
   <icell2d> <xc> <yc> <ncvert> <icvert(ncvert)>
-  <icell2d> <xc> <yc> <ncvert> <icvert(ncvert)>
-  ...
+  ...]
 END CELL2D
diff --git a/doc/mf6io/mf6ivar/tex/gwf-disu-vertices.dat b/doc/mf6io/mf6ivar/tex/gwf-disu-vertices.dat
index 6831f23b5ff..a4bc80c5453 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-disu-vertices.dat
+++ b/doc/mf6io/mf6ivar/tex/gwf-disu-vertices.dat
@@ -1,5 +1,5 @@
 BEGIN VERTICES
+  [<iv> <xv> <yv>
   <iv> <xv> <yv>
-  <iv> <xv> <yv>
-  ...
+  ...]
 END VERTICES
diff --git a/doc/mf6io/mf6ivar/tex/gwf-evt-period.dat b/doc/mf6io/mf6ivar/tex/gwf-evt-period.dat
index 380761217d9..8b5288455ce 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-evt-period.dat
+++ b/doc/mf6io/mf6ivar/tex/gwf-evt-period.dat
@@ -1,5 +1,5 @@
 BEGIN PERIOD <iper>
-  <cellid(ncelldim)> <@surface@> <@rate@> <@depth@> <@pxdp(nseg-1)@> <@petm(nseg-1)@> [<@petm0@>] [<@aux(naux)@>] [<boundname>]
-  <cellid(ncelldim)> <@surface@> <@rate@> <@depth@> <@pxdp(nseg-1)@> <@petm(nseg-1)@> [<@petm0@>] [<@aux(naux)@>] [<boundname>]
+  <cellid(ncelldim)> <@surface@> <@rate@> <@depth@> [<@pxdp(nseg-1)@>] [<@petm(nseg-1)@>] [<@petm0@>] [<@aux(naux)@>] [<boundname>]
+  <cellid(ncelldim)> <@surface@> <@rate@> <@depth@> [<@pxdp(nseg-1)@>] [<@petm(nseg-1)@>] [<@petm0@>] [<@aux(naux)@>] [<boundname>]
   ...
 END PERIOD
diff --git a/doc/mf6io/mf6ivar/tex/gwf-evta-desc.tex b/doc/mf6io/mf6ivar/tex/gwf-evta-desc.tex
index 3dbded6c6c1..987b185558b 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-evta-desc.tex
+++ b/doc/mf6io/mf6ivar/tex/gwf-evta-desc.tex
@@ -37,11 +37,11 @@
 
 \item \texttt{surface}---is the elevation of the ET surface ($L$).
 
-\item \texttt{rate}---is the maximum ET flux rate ($LT^{-1}$).
+\item \textcolor{blue}{\texttt{rate}---is the maximum ET flux rate ($LT^{-1}$).}
 
 \item \texttt{depth}---is the ET extinction depth ($L$).
 
-\item \texttt{aux(iaux)}---is an array of values for auxiliary variable AUX(IAUX), where iaux is a value from 1 to NAUX, and AUX(IAUX) must be listed as part of the auxiliary variables.  A separate array can be specified for each auxiliary variable.  If an array is not specified for an auxiliary variable, then a value of zero is assigned.  If the value specified here for the auxiliary variable is the same as auxmultname, then the evapotranspiration rate will be multiplied by this array.
+\item \textcolor{blue}{\texttt{aux}---is an array of values for auxiliary variable AUX(IAUX), where iaux is a value from 1 to NAUX, and AUX(IAUX) must be listed as part of the auxiliary variables.  A separate array can be specified for each auxiliary variable.  If an array is not specified for an auxiliary variable, then a value of zero is assigned.  If the value specified here for the auxiliary variable is the same as auxmultname, then the evapotranspiration rate will be multiplied by this array.}
 
 \end{description}
 
diff --git a/doc/mf6io/mf6ivar/tex/gwf-evta-period.dat b/doc/mf6io/mf6ivar/tex/gwf-evta-period.dat
index 2fe138e798b..185b433f84e 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-evta-period.dat
+++ b/doc/mf6io/mf6ivar/tex/gwf-evta-period.dat
@@ -7,6 +7,6 @@ BEGIN PERIOD <iper>
     <rate(ncol*nrow; ncpl)> -- READARRAY
   DEPTH
     <depth(ncol*nrow; ncpl)> -- READARRAY
-  AUX(IAUX)
-    <aux(iaux)(ncol*nrow; ncpl)> -- READARRAY
+  AUX
+    <aux(ncol*nrow; ncpl)> -- READARRAY
 END PERIOD
diff --git a/doc/mf6io/mf6ivar/tex/gwf-lak-connectiondata.dat b/doc/mf6io/mf6ivar/tex/gwf-lak-connectiondata.dat
index 4a5c586a689..aaab3cb1544 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-lak-connectiondata.dat
+++ b/doc/mf6io/mf6ivar/tex/gwf-lak-connectiondata.dat
@@ -1,5 +1,5 @@
 BEGIN CONNECTIONDATA
-  <lakeno> <iconn> <cellid(ncelldim)> <claktype> <bedleak> <belev> <telev> <connlen> <connwidth>
-  <lakeno> <iconn> <cellid(ncelldim)> <claktype> <bedleak> <belev> <telev> <connlen> <connwidth>
+  <ifno> <iconn> <cellid(ncelldim)> <claktype> <bedleak> <belev> <telev> <connlen> <connwidth>
+  <ifno> <iconn> <cellid(ncelldim)> <claktype> <bedleak> <belev> <telev> <connlen> <connwidth>
   ...
 END CONNECTIONDATA
diff --git a/doc/mf6io/mf6ivar/tex/gwf-lak-desc.tex b/doc/mf6io/mf6ivar/tex/gwf-lak-desc.tex
index ad5ac4b7d71..5db6336bb82 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-lak-desc.tex
+++ b/doc/mf6io/mf6ivar/tex/gwf-lak-desc.tex
@@ -69,11 +69,11 @@
 \item \textbf{Block: PACKAGEDATA}
 
 \begin{description}
-\item \texttt{lakeno}---integer value that defines the lake number associated with the specified PACKAGEDATA data on the line. LAKENO must be greater than zero and less than or equal to NLAKES. Lake information must be specified for every lake or the program will terminate with an error.  The program will also terminate with an error if information for a lake is specified more than once.
+\item \texttt{ifno}---integer value that defines the feature (lake) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NLAKES. Lake information must be specified for every lake or the program will terminate with an error.  The program will also terminate with an error if information for a lake is specified more than once.
 
 \item \texttt{strt}---real value that defines the starting stage for the lake.
 
-\item \texttt{nlakeconn}---integer value that defines the number of GWF cells connected to this (LAKENO) lake. There can only be one vertical lake connection to each GWF cell. NLAKECONN must be greater than zero.
+\item \texttt{nlakeconn}---integer value that defines the number of GWF cells connected to this (IFNO) lake. There can only be one vertical lake connection to each GWF cell. NLAKECONN must be greater than zero.
 
 \item \textcolor{blue}{\texttt{aux}---represents the values of the auxiliary variables for each lake. The values of auxiliary variables must be present for each lake. The values must be specified in the order of the auxiliary variables specified in the OPTIONS block.  If the package supports time series and the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value.}
 
@@ -83,15 +83,15 @@
 \item \textbf{Block: CONNECTIONDATA}
 
 \begin{description}
-\item \texttt{lakeno}---integer value that defines the lake number associated with the specified CONNECTIONDATA data on the line. LAKENO must be greater than zero and less than or equal to NLAKES. Lake connection information must be specified for every lake connection to the GWF model (NLAKECONN) or the program will terminate with an error.  The program will also terminate with an error if connection information for a lake connection to the GWF model is specified more than once.
+\item \texttt{ifno}---integer value that defines the feature (lake) number associated with the specified CONNECTIONDATA data on the line. IFNO must be greater than zero and less than or equal to NLAKES. Lake connection information must be specified for every lake connection to the GWF model (NLAKECONN) or the program will terminate with an error.  The program will also terminate with an error if connection information for a lake connection to the GWF model is specified more than once.
 
-\item \texttt{iconn}---integer value that defines the GWF connection number for this lake connection entry. ICONN must be greater than zero and less than or equal to NLAKECONN for lake LAKENO.
+\item \texttt{iconn}---integer value that defines the GWF connection number for this lake connection entry. ICONN must be greater than zero and less than or equal to NLAKECONN for lake IFNO.
 
 \item \texttt{cellid}---is the cell identifier, and depends on the type of grid that is used for the simulation.  For a structured grid that uses the DIS input file, CELLID is the layer, row, and column.   For a grid that uses the DISV input file, CELLID is the layer and CELL2D number.  If the model uses the unstructured discretization (DISU) input file, CELLID is the node number for the cell.
 
 \item \texttt{claktype}---character string that defines the lake-GWF connection type for the lake connection. Possible lake-GWF connection type strings include:  VERTICAL--character keyword to indicate the lake-GWF connection is vertical  and connection conductance calculations use the hydraulic conductivity corresponding to the $K_{33}$ tensor component defined for CELLID in the NPF package. HORIZONTAL--character keyword to indicate the lake-GWF connection is horizontal and connection conductance calculations use the hydraulic conductivity corresponding to the $K_{11}$ tensor component defined for CELLID in the NPF package. EMBEDDEDH--character keyword to indicate the lake-GWF connection is embedded in a single cell and connection conductance calculations use the hydraulic conductivity corresponding to the $K_{11}$ tensor component defined for CELLID in the NPF package. EMBEDDEDV--character keyword to indicate the lake-GWF connection is embedded in a single cell and connection conductance calculations use the hydraulic conductivity corresponding to the $K_{33}$ tensor component defined for CELLID in the NPF package. Embedded lakes can only be connected to a single cell (NLAKECONN = 1) and there must be a lake table associated with each embedded lake.
 
-\item \texttt{bedleak}---character string or real value that defines the bed leakance for the lake-GWF connection. BEDLEAK must be greater than or equal to zero or specified to be NONE. If BEDLEAK is specified to be NONE, the lake-GWF connection conductance is solely a function of aquifer properties in the connected GWF cell and lakebed sediments are assumed to be absent.
+\item \texttt{bedleak}---real value or character string that defines the bed leakance for the lake-GWF connection. BEDLEAK must be greater than or equal to zero, equal to the DNODATA value (3.0E+30), or specified to be NONE. If DNODATA or NONE is specified for BEDLEAK, the lake-GWF connection conductance is solely a function of aquifer properties in the connected GWF cell and lakebed sediments are assumed to be absent. Warning messages will be issued if NONE is specified. Eventually the ability to specify NONE will be deprecated and cause MODFLOW 6 to terminate with an error.
 
 \item \texttt{belev}---real value that defines the bottom elevation for a HORIZONTAL lake-GWF connection. Any value can be specified if CLAKTYPE is VERTICAL, EMBEDDEDH, or EMBEDDEDV. If CLAKTYPE is HORIZONTAL and BELEV is not equal to TELEV, BELEV must be greater than or equal to the bottom of the GWF cell CELLID. If BELEV is equal to TELEV, BELEV is reset to the bottom of the GWF cell CELLID.
 
@@ -105,7 +105,7 @@
 \item \textbf{Block: TABLES}
 
 \begin{description}
-\item \texttt{lakeno}---integer value that defines the lake number associated with the specified TABLES data on the line. LAKENO must be greater than zero and less than or equal to NLAKES. The program will terminate with an error if table information for a lake is specified more than once or the number of specified tables is less than NTABLES.
+\item \texttt{ifno}---integer value that defines the feature (lake) number associated with the specified TABLES data on the line. IFNO must be greater than zero and less than or equal to NLAKES. The program will terminate with an error if table information for a lake is specified more than once or the number of specified tables is less than NTABLES.
 
 \item \texttt{TAB6}---keyword to specify that record corresponds to a table file.
 
@@ -173,7 +173,7 @@
 
 \item \textcolor{blue}{\texttt{withdrawal}---real or character value that defines the maximum withdrawal rate $(L^3 T^{-1})$ for the lake. Value must be greater than or equal to zero. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value.}
 
-\item \textcolor{blue}{\texttt{rate}---real or character value that defines the extraction rate for the lake outflow. A positive value indicates inflow and a negative value indicates outflow from the lake. RATE only applies to active (IBOUND $>$ 0) lakes. A specified RATE is only applied if COUTTYPE for the OUTLETNO is SPECIFIED. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. By default, the RATE for each SPECIFIED lake outlet is zero.}
+\item \textcolor{blue}{\texttt{rate}---real or character value that defines the extraction rate for the lake outflow. A positive value indicates inflow and a negative value indicates outflow from the lake. RATE only applies to outlets associated with active lakes (STATUS is ACTIVE). A specified RATE is only applied if COUTTYPE for the OUTLETNO is SPECIFIED. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. By default, the RATE for each SPECIFIED lake outlet is zero.}
 
 \item \textcolor{blue}{\texttt{invert}---real or character value that defines the invert elevation for the lake outlet. A specified INVERT value is only used for active lakes if COUTTYPE for lake outlet OUTLETNO is not SPECIFIED. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value.}
 
diff --git a/doc/mf6io/mf6ivar/tex/gwf-lak-packagedata.dat b/doc/mf6io/mf6ivar/tex/gwf-lak-packagedata.dat
index 7ef345a403f..11adb3c02eb 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-lak-packagedata.dat
+++ b/doc/mf6io/mf6ivar/tex/gwf-lak-packagedata.dat
@@ -1,5 +1,5 @@
 BEGIN PACKAGEDATA
-  <lakeno> <strt> <nlakeconn> [<@aux(naux)@>] [<boundname>]
-  <lakeno> <strt> <nlakeconn> [<@aux(naux)@>] [<boundname>]
+  <ifno> <strt> <nlakeconn> [<@aux(naux)@>] [<boundname>]
+  <ifno> <strt> <nlakeconn> [<@aux(naux)@>] [<boundname>]
   ...
 END PACKAGEDATA
diff --git a/doc/mf6io/mf6ivar/tex/gwf-lak-tables.dat b/doc/mf6io/mf6ivar/tex/gwf-lak-tables.dat
index b009e0b0d41..e81e4988592 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-lak-tables.dat
+++ b/doc/mf6io/mf6ivar/tex/gwf-lak-tables.dat
@@ -1,5 +1,5 @@
 BEGIN TABLES
-  <lakeno> TAB6 FILEIN <tab6_filename>
-  <lakeno> TAB6 FILEIN <tab6_filename>
+  <ifno> TAB6 FILEIN <tab6_filename>
+  <ifno> TAB6 FILEIN <tab6_filename>
   ...
 END TABLES
diff --git a/doc/mf6io/mf6ivar/tex/gwf-maw-connectiondata.dat b/doc/mf6io/mf6ivar/tex/gwf-maw-connectiondata.dat
index 2ca671003dc..9f20aa841b5 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-maw-connectiondata.dat
+++ b/doc/mf6io/mf6ivar/tex/gwf-maw-connectiondata.dat
@@ -1,5 +1,5 @@
 BEGIN CONNECTIONDATA
-  <wellno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
-  <wellno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
+  <ifno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
+  <ifno> <icon> <cellid(ncelldim)> <scrn_top> <scrn_bot> <hk_skin> <radius_skin>
   ...
 END CONNECTIONDATA
diff --git a/doc/mf6io/mf6ivar/tex/gwf-maw-desc.tex b/doc/mf6io/mf6ivar/tex/gwf-maw-desc.tex
index abb1023e655..d3648dc02e9 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-maw-desc.tex
+++ b/doc/mf6io/mf6ivar/tex/gwf-maw-desc.tex
@@ -65,7 +65,7 @@
 \item \textbf{Block: PACKAGEDATA}
 
 \begin{description}
-\item \texttt{wellno}---integer value that defines the well number associated with the specified PACKAGEDATA data on the line. WELLNO must be greater than zero and less than or equal to NMAWWELLS. Multi-aquifer well information must be specified for every multi-aquifer well or the program will terminate with an error.  The program will also terminate with an error if information for a multi-aquifer well is specified more than once.
+\item \texttt{ifno}---integer value that defines the feature (well) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NMAWWELLS. Multi-aquifer well information must be specified for every multi-aquifer well or the program will terminate with an error.  The program will also terminate with an error if information for a multi-aquifer well is specified more than once.
 
 \item \texttt{radius}---radius for the multi-aquifer well. The program will terminate with an error if the radius is less than or equal to zero.
 
@@ -75,7 +75,7 @@
 
 \item \texttt{condeqn}---character string that defines the conductance equation that is used to calculate the saturated conductance for the multi-aquifer well. Possible multi-aquifer well CONDEQN strings include: SPECIFIED--character keyword to indicate the multi-aquifer well saturated conductance will be specified.  THIEM--character keyword to indicate the multi-aquifer well saturated conductance will be calculated using the Thiem equation, which considers the cell top and bottom, aquifer hydraulic conductivity, and effective cell and well radius.  SKIN--character keyword to indicate that the multi-aquifer well saturated conductance will be calculated using the cell top and bottom, aquifer and screen hydraulic conductivity, and well and skin radius.  CUMULATIVE--character keyword to indicate that the multi-aquifer well saturated conductance will be calculated using a combination of the Thiem and SKIN equations.  MEAN--character keyword to indicate the multi-aquifer well saturated conductance will be calculated using the aquifer and screen top and bottom, aquifer and screen hydraulic conductivity, and well and skin radius. The CUMULATIVE conductance equation is identical to the SKIN LOSSTYPE in the Multi-Node Well (MNW2) package for MODFLOW-2005. The program will terminate with an error condition if CONDEQN is SKIN or CUMULATIVE and the calculated saturated conductance is less than zero; if an error condition occurs, it is suggested that the THEIM or MEAN conductance equations be used for these multi-aquifer wells.
 
-\item \texttt{ngwfnodes}---integer value that defines the number of GWF nodes connected to this (WELLNO) multi-aquifer well. NGWFNODES must be greater than zero.
+\item \texttt{ngwfnodes}---integer value that defines the number of GWF nodes connected to this (IFNO) multi-aquifer well. NGWFNODES must be greater than zero.
 
 \item \textcolor{blue}{\texttt{aux}---represents the values of the auxiliary variables for each multi-aquifer well. The values of auxiliary variables must be present for each multi-aquifer well. The values must be specified in the order of the auxiliary variables specified in the OPTIONS block.  If the package supports time series and the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value.}
 
@@ -85,15 +85,15 @@
 \item \textbf{Block: CONNECTIONDATA}
 
 \begin{description}
-\item \texttt{wellno}---integer value that defines the well number associated with the specified CONNECTIONDATA data on the line. WELLNO must be greater than zero and less than or equal to NMAWWELLS. Multi-aquifer well connection information must be specified for every multi-aquifer well connection to the GWF model (NGWFNODES) or the program will terminate with an error.  The program will also terminate with an error if connection information for a multi-aquifer well connection to the GWF model is specified more than once.
+\item \texttt{ifno}---integer value that defines the feature (well) number associated with the specified CONNECTIONDATA data on the line. IFNO must be greater than zero and less than or equal to NMAWWELLS. Multi-aquifer well connection information must be specified for every multi-aquifer well connection to the GWF model (NGWFNODES) or the program will terminate with an error.  The program will also terminate with an error if connection information for a multi-aquifer well connection to the GWF model is specified more than once.
 
-\item \texttt{icon}---integer value that defines the GWF connection number for this multi-aquifer well connection entry. ICONN must be greater than zero and less than or equal to NGWFNODES for multi-aquifer well WELLNO.
+\item \texttt{icon}---integer value that defines the GWF connection number for this multi-aquifer well connection entry. ICONN must be greater than zero and less than or equal to NGWFNODES for multi-aquifer well IFNO.
 
 \item \texttt{cellid}---is the cell identifier, and depends on the type of grid that is used for the simulation.  For a structured grid that uses the DIS input file, CELLID is the layer, row, and column.   For a grid that uses the DISV input file, CELLID is the layer and CELL2D number.  If the model uses the unstructured discretization (DISU) input file, CELLID is the node number for the cell. One or more screened intervals can be connected to the same CELLID if CONDEQN for a well is MEAN. The program will terminate with an error if MAW wells using SPECIFIED, THIEM, SKIN, or CUMULATIVE conductance equations have more than one connection to the same CELLID.
 
 \item \texttt{scrn\_top}---value that defines the top elevation of the screen for the multi-aquifer well connection. If CONDEQN is SPECIFIED, THIEM, SKIN, or COMPOSITE, SCRN\_TOP can be any value and is set to the top of the cell. If CONDEQN is MEAN, SCRN\_TOP is set to the multi-aquifer well connection cell top if the specified value is greater than the cell top. The program will terminate with an error if the screen top is less than the screen bottom.
 
-\item \texttt{scrn\_bot}---value that defines the bottom elevation of the screen for the multi-aquifer well connection. If CONDEQN is SPECIFIED, THIEM, SKIN, or COMPOSITE, SCRN\_BOT can be any value is set to the bottom of the cell. If CONDEQN is MEAN, SCRN\_BOT is set to the multi-aquifer well connection cell bottom if the specified value is less than the cell bottom. The program will terminate with an error if the screen bottom is greater than the screen top.
+\item \texttt{scrn\_bot}---value that defines the bottom elevation of the screen for the multi-aquifer well connection. If CONDEQN is SPECIFIED, THIEM, SKIN, or COMPOSITE, SCRN\_BOT can be any value and is set to the bottom of the cell. If CONDEQN is MEAN, SCRN\_BOT is set to the multi-aquifer well connection cell bottom if the specified value is less than the cell bottom. The program will terminate with an error if the screen bottom is greater than the screen top.
 
 \item \texttt{hk\_skin}---value that defines the skin (filter pack) hydraulic conductivity (if CONDEQN for the multi-aquifer well is SKIN, CUMULATIVE, or MEAN) or conductance (if CONDEQN for the multi-aquifer well is SPECIFIED) for each GWF node connected to the multi-aquifer well (NGWFNODES). If CONDEQN is SPECIFIED, HK\_SKIN must be greater than or equal to zero.  HK\_SKIN can be any value if CONDEQN is THIEM. Otherwise, HK\_SKIN must be greater than zero. If CONDEQN is SKIN, the contrast between the cell transmissivity (the product of geometric mean horizontal hydraulic conductivity and the cell thickness) and the well transmissivity (the product of HK\_SKIN and the screen thicknesses) must be greater than one in node CELLID or the program will terminate with an error condition; if an error condition occurs, it is suggested that the HK\_SKIN be reduced to a value less than K11 and K22 in node CELLID or the THEIM or MEAN conductance equations be used for these multi-aquifer wells.
 
@@ -105,7 +105,7 @@
 \begin{description}
 \item \texttt{iper}---integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block.
 
-\item \texttt{wellno}---integer value that defines the well number associated with the specified PERIOD data on the line. WELLNO must be greater than zero and less than or equal to NMAWWELLS.
+\item \texttt{ifno}---integer value that defines the well number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NMAWWELLS.
 
 \item \texttt{mawsetting}---line of information that is parsed into a keyword and values.  Keyword values that can be used to start the MAWSETTING string include: STATUS, FLOWING\_WELL, RATE, WELL\_HEAD, HEAD\_LIMIT, SHUT\_OFF, RATE\_SCALING, and AUXILIARY.
 
@@ -130,7 +130,7 @@
 
 \item \texttt{fwrlen}---length used to reduce the conductance of the flowing well.  When the head in the well drops below the well top plus the reduction length, then the conductance is reduced.  This reduction length can be used to improve the stability of simulations with flowing wells so that there is not an abrupt change in flowing well rates.
 
-\item \textcolor{blue}{\texttt{rate}---is the volumetric pumping rate for the multi-aquifer well. A positive value indicates recharge and a negative value indicates discharge (pumping). RATE only applies to active (IBOUND $>$ 0) multi-aquifer wells. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. By default, the RATE for each multi-aquifer well is zero.}
+\item \textcolor{blue}{\texttt{rate}---is the volumetric pumping rate for the multi-aquifer well. A positive value indicates recharge and a negative value indicates discharge (pumping). RATE only applies to active (STATUS is ACTIVE) multi-aquifer wells. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. By default, the RATE for each multi-aquifer well is zero.}
 
 \item \textcolor{blue}{\texttt{well\_head}---is the head in the multi-aquifer well. WELL\_HEAD is only applied to constant head (STATUS is CONSTANT) and inactive (STATUS is INACTIVE) multi-aquifer wells. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value. The program will terminate with an error if WELL\_HEAD is less than the bottom of the well.}
 
diff --git a/doc/mf6io/mf6ivar/tex/gwf-maw-packagedata.dat b/doc/mf6io/mf6ivar/tex/gwf-maw-packagedata.dat
index 087d9728c06..da714ff562a 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-maw-packagedata.dat
+++ b/doc/mf6io/mf6ivar/tex/gwf-maw-packagedata.dat
@@ -1,5 +1,5 @@
 BEGIN PACKAGEDATA
-  <wellno> <radius> <bottom> <strt> <condeqn> <ngwfnodes> [<@aux(naux)@>] [<boundname>]
-  <wellno> <radius> <bottom> <strt> <condeqn> <ngwfnodes> [<@aux(naux)@>] [<boundname>]
+  <ifno> <radius> <bottom> <strt> <condeqn> <ngwfnodes> [<@aux(naux)@>] [<boundname>]
+  <ifno> <radius> <bottom> <strt> <condeqn> <ngwfnodes> [<@aux(naux)@>] [<boundname>]
   ...
 END PACKAGEDATA
diff --git a/doc/mf6io/mf6ivar/tex/gwf-maw-period.dat b/doc/mf6io/mf6ivar/tex/gwf-maw-period.dat
index 767f7419bee..9b67c1b650f 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-maw-period.dat
+++ b/doc/mf6io/mf6ivar/tex/gwf-maw-period.dat
@@ -1,5 +1,5 @@
 BEGIN PERIOD <iper>
-  <wellno> <mawsetting>
-  <wellno> <mawsetting>
+  <ifno> <mawsetting>
+  <ifno> <mawsetting>
   ...
 END PERIOD
diff --git a/doc/mf6io/mf6ivar/tex/gwf-rcha-desc.tex b/doc/mf6io/mf6ivar/tex/gwf-rcha-desc.tex
index c8ed6e6cda9..a3230eee906 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-rcha-desc.tex
+++ b/doc/mf6io/mf6ivar/tex/gwf-rcha-desc.tex
@@ -21,7 +21,7 @@
 
 \item \texttt{FILEIN}---keyword to specify that an input filename is expected next.
 
-\item \texttt{tas6\_filename}---defines a time-array-series file defining a time-array series that can be used to assign time-varying values. See the Time-Variable Input section for instructions on using the time-array series capability.
+\item \texttt{tas6\_filename}---defines a time-array-series file defining a time-array series that can be used to assign time-varying values. See the ``Time-Variable Input'' section for instructions on using the time-array series capability.
 
 \item \texttt{OBS6}---keyword to specify that record corresponds to an observations file.
 
@@ -35,9 +35,9 @@
 
 \item \texttt{irch}---IRCH is the layer number that defines the layer in each vertical column where recharge is applied. If IRCH is omitted, recharge by default is applied to cells in layer 1.  IRCH can only be used if READASARRAYS is specified in the OPTIONS block.  If IRCH is specified, it must be specified as the first variable in the PERIOD block or MODFLOW will terminate with an error.
 
-\item \texttt{recharge}---is the recharge flux rate ($LT^{-1}$).  This rate is multiplied inside the program by the surface area of the cell to calculate the volumetric recharge rate. The recharge array may be defined by a time-array series (see the "Using Time-Array Series in a Package" section).
+\item \textcolor{blue}{\texttt{recharge}---is the recharge flux rate ($LT^{-1}$).  This rate is multiplied inside the program by the surface area of the cell to calculate the volumetric recharge rate. The recharge array may be defined by a time-array series (see the "Using Time-Array Series in a Package" section).}
 
-\item \texttt{aux}---is an array of values for auxiliary variable aux(iaux), where iaux is a value from 1 to naux, and aux(iaux) must be listed as part of the auxiliary variables.  A separate array can be specified for each auxiliary variable.  If an array is not specified for an auxiliary variable, then a value of zero is assigned.  If the value specified here for the auxiliary variable is the same as auxmultname, then the recharge array will be multiplied by this array.
+\item \textcolor{blue}{\texttt{aux}---is an array of values for auxiliary variable aux(iaux), where iaux is a value from 1 to naux, and aux(iaux) must be listed as part of the auxiliary variables.  A separate array can be specified for each auxiliary variable.  If an array is not specified for an auxiliary variable, then a value of zero is assigned.  If the value specified here for the auxiliary variable is the same as auxmultname, then the recharge array will be multiplied by this array.}
 
 \end{description}
 
diff --git a/doc/mf6io/mf6ivar/tex/gwf-sfr-connectiondata.dat b/doc/mf6io/mf6ivar/tex/gwf-sfr-connectiondata.dat
index 142b8e1035d..0b5fa83dad4 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-sfr-connectiondata.dat
+++ b/doc/mf6io/mf6ivar/tex/gwf-sfr-connectiondata.dat
@@ -1,5 +1,5 @@
 BEGIN CONNECTIONDATA
-  <rno> [<ic(ncon(rno))>]
-  <rno> [<ic(ncon(rno))>]
+  <ifno> [<ic(ncon(ifno))>]
+  <ifno> [<ic(ncon(ifno))>]
   ...
 END CONNECTIONDATA
diff --git a/doc/mf6io/mf6ivar/tex/gwf-sfr-crosssections.dat b/doc/mf6io/mf6ivar/tex/gwf-sfr-crosssections.dat
index 83c6790a27c..8b38fa33781 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-sfr-crosssections.dat
+++ b/doc/mf6io/mf6ivar/tex/gwf-sfr-crosssections.dat
@@ -1,5 +1,5 @@
 BEGIN CROSSSECTIONS
-  <rno> TAB6 FILEIN <tab6_filename>
-  <rno> TAB6 FILEIN <tab6_filename>
+  <ifno> TAB6 FILEIN <tab6_filename>
+  <ifno> TAB6 FILEIN <tab6_filename>
   ...
 END CROSSSECTIONS
diff --git a/doc/mf6io/mf6ivar/tex/gwf-sfr-desc.tex b/doc/mf6io/mf6ivar/tex/gwf-sfr-desc.tex
index b0664a7f91f..2f72a3458a2 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-sfr-desc.tex
+++ b/doc/mf6io/mf6ivar/tex/gwf-sfr-desc.tex
@@ -65,9 +65,9 @@
 \item \textbf{Block: PACKAGEDATA}
 
 \begin{description}
-\item \texttt{rno}---integer value that defines the reach number associated with the specified PACKAGEDATA data on the line. RNO must be greater than zero and less than or equal to NREACHES. Reach information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if information for a reach is specified more than once.
+\item \texttt{ifno}---integer value that defines the feature (reach) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NREACHES. Reach information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if information for a reach is specified more than once.
 
-\item \texttt{cellid}---The keyword `NONE' must be specified for reaches that are not connected to an underlying GWF cell. The keyword `NONE' is used for reaches that are in cells that have IDOMAIN values less than one or are in areas not covered by the GWF model grid. Reach-aquifer flow is not calculated if the keyword `NONE' is specified.
+\item \texttt{cellid}---is the cell identifier, and depends on the type of grid that is used for the simulation. For a structured grid that uses the DIS input file, CELLID is the layer, row, and column. For a grid that uses the DISV input file, CELLID is the layer and CELL2D number. If the model uses the unstructured discretization (DISU) input file, CELLID is the node number for the cell. For reaches that are not connected to an underlying GWF cell, a zero should be specified for each grid dimension. For example, for a DIS grid a CELLID of 0 0 0 should be specified. Reach-aquifer flow is not calculated for unconnected reaches. The keyword NONE can be still be specified to identify unconnected reaches for backward compatibility with previous versions of MODFLOW 6 but eventually NONE will be deprecated and will cause MODFLOW 6 to terminate with an error.
 
 \item \texttt{rlen}---real value that defines the reach length. RLEN must be greater than zero.
 
@@ -77,13 +77,13 @@
 
 \item \texttt{rtp}---real value that defines the bottom elevation of the reach.
 
-\item \texttt{rbth}---real value that defines the thickness of the reach streambed. RBTH can be any value if CELLID is `NONE'. Otherwise, RBTH must be greater than zero.
+\item \texttt{rbth}---real value that defines the thickness of the reach streambed. RBTH can be any value if the reach is not connected to an underlying GWF cell. Otherwise, RBTH must be greater than zero.
 
-\item \texttt{rhk}---real value that defines the hydraulic conductivity of the reach streambed. RHK can be any positive value if CELLID is `NONE'. Otherwise, RHK must be greater than zero.
+\item \texttt{rhk}---real value that defines the hydraulic conductivity of the reach streambed. RHK can be any positive value if the reach is not connected to an underlying GWF cell. Otherwise, RHK must be greater than zero.
 
 \item \textcolor{blue}{\texttt{man}---real or character value that defines the Manning's roughness coefficient for the reach. MAN must be greater than zero.  If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value.}
 
-\item \texttt{ncon}---integer value that defines the number of reaches connected to the reach.  If a value of zero is specified for NCON an entry for RNO is still required in the subsequent CONNECTIONDATA block.
+\item \texttt{ncon}---integer value that defines the number of reaches connected to the reach.  If a value of zero is specified for NCON an entry for IFNO is still required in the subsequent CONNECTIONDATA block.
 
 \item \textcolor{blue}{\texttt{ustrf}---real value that defines the fraction of upstream flow from each upstream reach that is applied as upstream inflow to the reach. The sum of all USTRF values for all reaches connected to the same upstream reach must be equal to one and USTRF must be greater than or equal to zero. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value.}
 
@@ -97,7 +97,7 @@
 \item \textbf{Block: CROSSSECTIONS}
 
 \begin{description}
-\item \texttt{rno}---integer value that defines the reach number associated with the specified cross-section table file on the line. RNO must be greater than zero and less than or equal to NREACHES. The program will also terminate with an error if table information for a reach is specified more than once.
+\item \texttt{ifno}---integer value that defines the feature (reach) number associated with the specified cross-section table file on the line. IFNO must be greater than zero and less than or equal to NREACHES. The program will also terminate with an error if table information for a reach is specified more than once.
 
 \item \texttt{TAB6}---keyword to specify that record corresponds to a cross-section table file.
 
@@ -109,7 +109,7 @@
 \item \textbf{Block: CONNECTIONDATA}
 
 \begin{description}
-\item \texttt{rno}---integer value that defines the reach number associated with the specified CONNECTIONDATA data on the line. RNO must be greater than zero and less than or equal to NREACHES. Reach connection information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if connection information for a reach is specified more than once.
+\item \texttt{ifno}---integer value that defines the feature (reach) number associated with the specified CONNECTIONDATA data on the line. IFNO must be greater than zero and less than or equal to NREACHES. Reach connection information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if connection information for a reach is specified more than once.
 
 \item \texttt{ic}---integer value that defines the reach number of the reach connected to the current reach and whether it is connected to the upstream or downstream end of the reach. Negative IC numbers indicate connected reaches are connected to the downstream end of the current reach. Positive IC numbers indicate connected reaches are connected to the upstream end of the current reach. The absolute value of IC must be greater than zero and less than or equal to NREACHES. IC should not be specified when NCON is zero but must be specified otherwise.
 
@@ -117,13 +117,13 @@
 \item \textbf{Block: DIVERSIONS}
 
 \begin{description}
-\item \texttt{rno}---integer value that defines the reach number associated with the specified DIVERSIONS data on the line. RNO must be greater than zero and less than or equal to NREACHES.  Reach diversion information must be specified for every reach with a NDV value greater than 0 or the program will terminate with an error.  The program will also terminate with an error if diversion information for a given reach diversion is specified more than once.
+\item \texttt{ifno}---integer value that defines the feature (reach) number associated with the specified DIVERSIONS data on the line. IFNO must be greater than zero and less than or equal to NREACHES.  Reach diversion information must be specified for every reach with a NDV value greater than 0 or the program will terminate with an error.  The program will also terminate with an error if diversion information for a given reach diversion is specified more than once.
 
-\item \texttt{idv}---integer value that defines the downstream diversion number for the diversion for reach RNO. IDV must be greater than zero and less than or equal to NDV for reach RNO.
+\item \texttt{idv}---integer value that defines the downstream diversion number for the diversion for reach IFNO. IDV must be greater than zero and less than or equal to NDV for reach IFNO.
 
-\item \texttt{iconr}---integer value that defines the downstream reach that will receive the diverted water. IDV must be greater than zero and less than or equal to NREACHES. Furthermore, reach  ICONR must be a downstream connection for reach RNO.
+\item \texttt{iconr}---integer value that defines the downstream reach that will receive the diverted water. IDV must be greater than zero and less than or equal to NREACHES. Furthermore, reach  ICONR must be a downstream connection for reach IFNO.
 
-\item \texttt{cprior}---character string value that defines the the prioritization system for the diversion, such as when insufficient water is available to meet all diversion stipulations, and is used in conjunction with the value of FLOW value specified in the STRESS\_PERIOD\_DATA section. Available diversion options include:  (1) CPRIOR = `FRACTION', then the amount of the diversion is computed as a fraction of the streamflow leaving reach RNO ($Q_{DS}$); in this case, 0.0 $\le$ DIVFLOW $\le$ 1.0.  (2) CPRIOR = `EXCESS', a diversion is made only if $Q_{DS}$ for reach RNO exceeds the value of DIVFLOW. If this occurs, then the quantity of water diverted is the excess flow ($Q_{DS} -$ DIVFLOW) and $Q_{DS}$ from reach RNO is set equal to DIVFLOW. This represents a flood-control type of diversion, as described by Danskin and Hanson (2002). (3) CPRIOR = `THRESHOLD', then if $Q_{DS}$ in reach RNO is less than the specified diversion flow DIVFLOW, no water is diverted from reach RNO. If $Q_{DS}$ in reach RNO is greater than or equal to DIVFLOW, DIVFLOW is diverted and $Q_{DS}$ is set to the remainder ($Q_{DS} -$ DIVFLOW)). This approach assumes that once flow in the stream is sufficiently low, diversions from the stream cease, and is the `priority' algorithm that originally was programmed into the STR1 Package (Prudic, 1989).  (4) CPRIOR = `UPTO' -- if $Q_{DS}$ in reach RNO is greater than or equal to the specified diversion flow DIVFLOW, $Q_{DS}$ is reduced by DIVFLOW. If $Q_{DS}$ in reach RNO is less than DIVFLOW, DIVFLOW is set to $Q_{DS}$ and there will be no flow available for reaches connected to downstream end of reach RNO.
+\item \texttt{cprior}---character string value that defines the the prioritization system for the diversion, such as when insufficient water is available to meet all diversion stipulations, and is used in conjunction with the value of FLOW value specified in the STRESS\_PERIOD\_DATA section. Available diversion options include:  (1) CPRIOR = `FRACTION', then the amount of the diversion is computed as a fraction of the streamflow leaving reach IFNO ($Q_{DS}$); in this case, 0.0 $\le$ DIVFLOW $\le$ 1.0.  (2) CPRIOR = `EXCESS', a diversion is made only if $Q_{DS}$ for reach IFNO exceeds the value of DIVFLOW. If this occurs, then the quantity of water diverted is the excess flow ($Q_{DS} -$ DIVFLOW) and $Q_{DS}$ from reach IFNO is set equal to DIVFLOW. This represents a flood-control type of diversion, as described by Danskin and Hanson (2002). (3) CPRIOR = `THRESHOLD', then if $Q_{DS}$ in reach IFNO is less than the specified diversion flow DIVFLOW, no water is diverted from reach IFNO. If $Q_{DS}$ in reach IFNO is greater than or equal to DIVFLOW, DIVFLOW is diverted and $Q_{DS}$ is set to the remainder ($Q_{DS} -$ DIVFLOW)). This approach assumes that once flow in the stream is sufficiently low, diversions from the stream cease, and is the `priority' algorithm that originally was programmed into the STR1 Package (Prudic, 1989).  (4) CPRIOR = `UPTO' -- if $Q_{DS}$ in reach IFNO is greater than or equal to the specified diversion flow DIVFLOW, $Q_{DS}$ is reduced by DIVFLOW. If $Q_{DS}$ in reach IFNO is less than DIVFLOW, DIVFLOW is set to $Q_{DS}$ and there will be no flow available for reaches connected to downstream end of reach IFNO.
 
 \end{description}
 \item \textbf{Block: PERIOD}
@@ -131,7 +131,7 @@
 \begin{description}
 \item \texttt{iper}---integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block.
 
-\item \texttt{rno}---integer value that defines the reach number associated with the specified PERIOD data on the line. RNO must be greater than zero and less than or equal to NREACHES.
+\item \texttt{ifno}---integer value that defines the feature (reach) number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NREACHES.
 
 \item \texttt{sfrsetting}---line of information that is parsed into a keyword and values.  Keyword values that can be used to start the SFRSETTING string include: STATUS, MANNING, STAGE, INFLOW, RAINFALL, EVAPORATION, RUNOFF, DIVERSION, UPSTREAM\_FRACTION, and AUXILIARY.
 
@@ -165,7 +165,7 @@
 
 \item \texttt{DIVERSION}---keyword to indicate diversion record.
 
-\item \texttt{idv}---an integer value specifying which diversion of reach RNO that DIVFLOW is being specified for.  Must be less or equal to ndv for the current reach (RNO).
+\item \texttt{idv}---an integer value specifying which diversion of reach IFNO that DIVFLOW is being specified for.  Must be less or equal to ndv for the current reach (IFNO).
 
 \item \textcolor{blue}{\texttt{divflow}---real or character value that defines the volumetric diversion (DIVFLOW) rate for the streamflow routing reach. If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value.}
 
diff --git a/doc/mf6io/mf6ivar/tex/gwf-sfr-diversions.dat b/doc/mf6io/mf6ivar/tex/gwf-sfr-diversions.dat
index b1cb9c378b1..ba6932e2933 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-sfr-diversions.dat
+++ b/doc/mf6io/mf6ivar/tex/gwf-sfr-diversions.dat
@@ -1,5 +1,5 @@
 BEGIN DIVERSIONS
-  <rno> <idv> <iconr> <cprior>
-  <rno> <idv> <iconr> <cprior>
+  <ifno> <idv> <iconr> <cprior>
+  <ifno> <idv> <iconr> <cprior>
   ...
 END DIVERSIONS
diff --git a/doc/mf6io/mf6ivar/tex/gwf-sfr-packagedata.dat b/doc/mf6io/mf6ivar/tex/gwf-sfr-packagedata.dat
index c5d4a45c403..dd18612d650 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-sfr-packagedata.dat
+++ b/doc/mf6io/mf6ivar/tex/gwf-sfr-packagedata.dat
@@ -1,5 +1,5 @@
 BEGIN PACKAGEDATA
-  <rno> <cellid(ncelldim)> <rlen> <rwid> <rgrd> <rtp> <rbth> <rhk> <@man@> <ncon> <@ustrf@> <ndv> [<@aux(naux)@>] [<boundname>]
-  <rno> <cellid(ncelldim)> <rlen> <rwid> <rgrd> <rtp> <rbth> <rhk> <@man@> <ncon> <@ustrf@> <ndv> [<@aux(naux)@>] [<boundname>]
+  <ifno> <cellid(ncelldim)> <rlen> <rwid> <rgrd> <rtp> <rbth> <rhk> <@man@> <ncon> <@ustrf@> <ndv> [<@aux(naux)@>] [<boundname>]
+  <ifno> <cellid(ncelldim)> <rlen> <rwid> <rgrd> <rtp> <rbth> <rhk> <@man@> <ncon> <@ustrf@> <ndv> [<@aux(naux)@>] [<boundname>]
   ...
 END PACKAGEDATA
diff --git a/doc/mf6io/mf6ivar/tex/gwf-sfr-period.dat b/doc/mf6io/mf6ivar/tex/gwf-sfr-period.dat
index 40fc6597787..77f03fe4ad1 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-sfr-period.dat
+++ b/doc/mf6io/mf6ivar/tex/gwf-sfr-period.dat
@@ -1,5 +1,5 @@
 BEGIN PERIOD <iper>
-  <rno> <sfrsetting>
-  <rno> <sfrsetting>
+  <ifno> <sfrsetting>
+  <ifno> <sfrsetting>
   ...
 END PERIOD
diff --git a/doc/mf6io/mf6ivar/tex/gwf-uzf-desc.tex b/doc/mf6io/mf6ivar/tex/gwf-uzf-desc.tex
index 88f4401eddc..1944e303cee 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-uzf-desc.tex
+++ b/doc/mf6io/mf6ivar/tex/gwf-uzf-desc.tex
@@ -71,7 +71,7 @@
 \item \textbf{Block: PACKAGEDATA}
 
 \begin{description}
-\item \texttt{iuzno}---integer value that defines the UZF cell number associated with the specified PACKAGEDATA data on the line. IUZNO must be greater than zero and less than or equal to NUZFCELLS.  UZF information must be specified for every UZF cell or the program will terminate with an error.  The program will also terminate with an error if information for a UZF cell is specified more than once.
+\item \texttt{ifno}---integer value that defines the feature (UZF object) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NUZFCELLS.  UZF information must be specified for every UZF cell or the program will terminate with an error.  The program will also terminate with an error if information for a UZF cell is specified more than once.
 
 \item \texttt{cellid}---is the cell identifier, and depends on the type of grid that is used for the simulation.  For a structured grid that uses the DIS input file, CELLID is the layer, row, and column.   For a grid that uses the DISV input file, CELLID is the layer and CELL2D number.  If the model uses the unstructured discretization (DISU) input file, CELLID is the node number for the cell.
 
@@ -99,7 +99,7 @@
 \begin{description}
 \item \texttt{iper}---integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block.
 
-\item \texttt{iuzno}---integer value that defines the UZF cell number associated with the specified PERIOD data on the line.
+\item \texttt{ifno}---integer value that defines the feature (UZF object) number associated with the specified PERIOD data on the line.
 
 \item \textcolor{blue}{\texttt{finf}---real or character value that defines the applied infiltration rate of the UZF cell ($LT^{-1}$). If the Options block includes a TIMESERIESFILE entry (see the ``Time-Variable Input'' section), values can be obtained from a time series by entering the time-series name in place of a numeric value.}
 
diff --git a/doc/mf6io/mf6ivar/tex/gwf-uzf-packagedata.dat b/doc/mf6io/mf6ivar/tex/gwf-uzf-packagedata.dat
index f035038f5dc..773eb0d8c1e 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-uzf-packagedata.dat
+++ b/doc/mf6io/mf6ivar/tex/gwf-uzf-packagedata.dat
@@ -1,5 +1,5 @@
 BEGIN PACKAGEDATA
-  <iuzno> <cellid(ncelldim)> <landflag> <ivertcon> <surfdep> <vks> <thtr> <thts> <thti> <eps> [<boundname>]
-  <iuzno> <cellid(ncelldim)> <landflag> <ivertcon> <surfdep> <vks> <thtr> <thts> <thti> <eps> [<boundname>]
+  <ifno> <cellid(ncelldim)> <landflag> <ivertcon> <surfdep> <vks> <thtr> <thts> <thti> <eps> [<boundname>]
+  <ifno> <cellid(ncelldim)> <landflag> <ivertcon> <surfdep> <vks> <thtr> <thts> <thti> <eps> [<boundname>]
   ...
 END PACKAGEDATA
diff --git a/doc/mf6io/mf6ivar/tex/gwf-uzf-period.dat b/doc/mf6io/mf6ivar/tex/gwf-uzf-period.dat
index 05bb378fcbc..38ce0a956ae 100644
--- a/doc/mf6io/mf6ivar/tex/gwf-uzf-period.dat
+++ b/doc/mf6io/mf6ivar/tex/gwf-uzf-period.dat
@@ -1,5 +1,5 @@
 BEGIN PERIOD <iper>
-  <iuzno> <@finf@> <@pet@> <@extdp@> <@extwc@> <@ha@> <@hroot@> <@rootact@> [<@aux(naux)@>]
-  <iuzno> <@finf@> <@pet@> <@extdp@> <@extwc@> <@ha@> <@hroot@> <@rootact@> [<@aux(naux)@>]
+  <ifno> <@finf@> <@pet@> <@extdp@> <@extwc@> <@ha@> <@hroot@> <@rootact@> [<@aux(naux)@>]
+  <ifno> <@finf@> <@pet@> <@extdp@> <@extwc@> <@ha@> <@hroot@> <@rootact@> [<@aux(naux)@>]
   ...
 END PERIOD
diff --git a/doc/mf6io/mf6ivar/tex/gwt-disu-cell2d.dat b/doc/mf6io/mf6ivar/tex/gwt-disu-cell2d.dat
index 27900d67235..f6d08961367 100644
--- a/doc/mf6io/mf6ivar/tex/gwt-disu-cell2d.dat
+++ b/doc/mf6io/mf6ivar/tex/gwt-disu-cell2d.dat
@@ -1,5 +1,5 @@
 BEGIN CELL2D
+  [<icell2d> <xc> <yc> <ncvert> <icvert(ncvert)>
   <icell2d> <xc> <yc> <ncvert> <icvert(ncvert)>
-  <icell2d> <xc> <yc> <ncvert> <icvert(ncvert)>
-  ...
+  ...]
 END CELL2D
diff --git a/doc/mf6io/mf6ivar/tex/gwt-disu-vertices.dat b/doc/mf6io/mf6ivar/tex/gwt-disu-vertices.dat
index 6831f23b5ff..a4bc80c5453 100644
--- a/doc/mf6io/mf6ivar/tex/gwt-disu-vertices.dat
+++ b/doc/mf6io/mf6ivar/tex/gwt-disu-vertices.dat
@@ -1,5 +1,5 @@
 BEGIN VERTICES
+  [<iv> <xv> <yv>
   <iv> <xv> <yv>
-  <iv> <xv> <yv>
-  ...
+  ...]
 END VERTICES
diff --git a/doc/mf6io/mf6ivar/tex/gwt-lkt-desc.tex b/doc/mf6io/mf6ivar/tex/gwt-lkt-desc.tex
index 29e18ed0fef..052725643c4 100644
--- a/doc/mf6io/mf6ivar/tex/gwt-lkt-desc.tex
+++ b/doc/mf6io/mf6ivar/tex/gwt-lkt-desc.tex
@@ -47,7 +47,7 @@
 \item \textbf{Block: PACKAGEDATA}
 
 \begin{description}
-\item \texttt{lakeno}---integer value that defines the lake number associated with the specified PACKAGEDATA data on the line. LAKENO must be greater than zero and less than or equal to NLAKES. Lake information must be specified for every lake or the program will terminate with an error.  The program will also terminate with an error if information for a lake is specified more than once.
+\item \texttt{ifno}---integer value that defines the feature (lake) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NLAKES. Lake information must be specified for every lake or the program will terminate with an error.  The program will also terminate with an error if information for a lake is specified more than once.
 
 \item \texttt{strt}---real value that defines the starting concentration for the lake.
 
@@ -61,9 +61,9 @@
 \begin{description}
 \item \texttt{iper}---integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block.
 
-\item \texttt{lakeno}---integer value that defines the lake number associated with the specified PERIOD data on the line. LAKENO must be greater than zero and less than or equal to NLAKES.
+\item \texttt{ifno}---integer value that defines the feature (lake) number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NLAKES.
 
-\item \texttt{laksetting}---line of information that is parsed into a keyword and values.  Keyword values that can be used to start the LAKSETTING string include: STATUS, CONCENTRATION, RAINFALL, EVAPORATION, RUNOFF, and AUXILIARY.  These settings are used to assign the concentration of associated with the corresponding flow terms.  Concentrations cannot be specified for all flow terms.  For example, the Lake Package supports a ``WITHDRAWAL'' flow term.  If this withdrawal term is active, then water will be withdrawn from the lake at the calculated concentration of the lake.
+\item \texttt{laksetting}---line of information that is parsed into a keyword and values.  Keyword values that can be used to start the LAKSETTING string include: STATUS, CONCENTRATION, RAINFALL, EVAPORATION, RUNOFF, EXT-INFLOW, and AUXILIARY.  These settings are used to assign the concentration of associated with the corresponding flow terms.  Concentrations cannot be specified for all flow terms.  For example, the Lake Package supports a ``WITHDRAWAL'' flow term.  If this withdrawal term is active, then water will be withdrawn from the lake at the calculated concentration of the lake.
 
 \begin{lstlisting}[style=blockdefinition]
 STATUS <status>
diff --git a/doc/mf6io/mf6ivar/tex/gwt-lkt-packagedata.dat b/doc/mf6io/mf6ivar/tex/gwt-lkt-packagedata.dat
index c3a9aeec732..c293a94d109 100644
--- a/doc/mf6io/mf6ivar/tex/gwt-lkt-packagedata.dat
+++ b/doc/mf6io/mf6ivar/tex/gwt-lkt-packagedata.dat
@@ -1,5 +1,5 @@
 BEGIN PACKAGEDATA
-  <lakeno> <strt> [<@aux(naux)@>] [<boundname>]
-  <lakeno> <strt> [<@aux(naux)@>] [<boundname>]
+  <ifno> <strt> [<@aux(naux)@>] [<boundname>]
+  <ifno> <strt> [<@aux(naux)@>] [<boundname>]
   ...
 END PACKAGEDATA
diff --git a/doc/mf6io/mf6ivar/tex/gwt-lkt-period.dat b/doc/mf6io/mf6ivar/tex/gwt-lkt-period.dat
index dfe899b47ef..da60631beac 100644
--- a/doc/mf6io/mf6ivar/tex/gwt-lkt-period.dat
+++ b/doc/mf6io/mf6ivar/tex/gwt-lkt-period.dat
@@ -1,5 +1,5 @@
 BEGIN PERIOD <iper>
-  <lakeno> <laksetting>
-  <lakeno> <laksetting>
+  <ifno> <laksetting>
+  <ifno> <laksetting>
   ...
 END PERIOD
diff --git a/doc/mf6io/mf6ivar/tex/gwt-mwt-desc.tex b/doc/mf6io/mf6ivar/tex/gwt-mwt-desc.tex
index b3bbbc87356..76beee6ffa4 100644
--- a/doc/mf6io/mf6ivar/tex/gwt-mwt-desc.tex
+++ b/doc/mf6io/mf6ivar/tex/gwt-mwt-desc.tex
@@ -47,7 +47,7 @@
 \item \textbf{Block: PACKAGEDATA}
 
 \begin{description}
-\item \texttt{mawno}---integer value that defines the well number associated with the specified PACKAGEDATA data on the line. MAWNO must be greater than zero and less than or equal to NMAWWELLS. Well information must be specified for every well or the program will terminate with an error.  The program will also terminate with an error if information for a well is specified more than once.
+\item \texttt{ifno}---integer value that defines the feature (well) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NMAWWELLS. Well information must be specified for every well or the program will terminate with an error.  The program will also terminate with an error if information for a well is specified more than once.
 
 \item \texttt{strt}---real value that defines the starting concentration for the well.
 
@@ -61,9 +61,9 @@
 \begin{description}
 \item \texttt{iper}---integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block.
 
-\item \texttt{mawno}---integer value that defines the well number associated with the specified PERIOD data on the line. MAWNO must be greater than zero and less than or equal to NMAWWELLS.
+\item \texttt{ifno}---integer value that defines the feature (well) number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NMAWWELLS.
 
-\item \texttt{mwtsetting}---line of information that is parsed into a keyword and values.  Keyword values that can be used to start the MWTSETTING string include: STATUS, CONCENTRATION, RAINFALL, EVAPORATION, RUNOFF, and AUXILIARY.  These settings are used to assign the concentration of associated with the corresponding flow terms.  Concentrations cannot be specified for all flow terms.  For example, the Multi-Aquifer Well Package supports a ``WITHDRAWAL'' flow term.  If this withdrawal term is active, then water will be withdrawn from the well at the calculated concentration of the well.
+\item \texttt{mwtsetting}---line of information that is parsed into a keyword and values.  Keyword values that can be used to start the MWTSETTING string include: STATUS, CONCENTRATION, RATE, and AUXILIARY.  These settings are used to assign the concentration associated with the corresponding flow terms.  Concentrations cannot be specified for all flow terms.  For example, the Multi-Aquifer Well Package supports a ``WITHDRAWAL'' flow term.  If this withdrawal term is active, then water will be withdrawn from the well at the calculated concentration of the well.
 
 \begin{lstlisting}[style=blockdefinition]
 STATUS <status>
diff --git a/doc/mf6io/mf6ivar/tex/gwt-mwt-packagedata.dat b/doc/mf6io/mf6ivar/tex/gwt-mwt-packagedata.dat
index 1e2b52667c3..c293a94d109 100644
--- a/doc/mf6io/mf6ivar/tex/gwt-mwt-packagedata.dat
+++ b/doc/mf6io/mf6ivar/tex/gwt-mwt-packagedata.dat
@@ -1,5 +1,5 @@
 BEGIN PACKAGEDATA
-  <mawno> <strt> [<@aux(naux)@>] [<boundname>]
-  <mawno> <strt> [<@aux(naux)@>] [<boundname>]
+  <ifno> <strt> [<@aux(naux)@>] [<boundname>]
+  <ifno> <strt> [<@aux(naux)@>] [<boundname>]
   ...
 END PACKAGEDATA
diff --git a/doc/mf6io/mf6ivar/tex/gwt-mwt-period.dat b/doc/mf6io/mf6ivar/tex/gwt-mwt-period.dat
index 6c43c850d50..35f8338041f 100644
--- a/doc/mf6io/mf6ivar/tex/gwt-mwt-period.dat
+++ b/doc/mf6io/mf6ivar/tex/gwt-mwt-period.dat
@@ -1,5 +1,5 @@
 BEGIN PERIOD <iper>
-  <mawno> <mwtsetting>
-  <mawno> <mwtsetting>
+  <ifno> <mwtsetting>
+  <ifno> <mwtsetting>
   ...
 END PERIOD
diff --git a/doc/mf6io/mf6ivar/tex/gwt-sft-desc.tex b/doc/mf6io/mf6ivar/tex/gwt-sft-desc.tex
index bed98a05116..7bd5b296985 100644
--- a/doc/mf6io/mf6ivar/tex/gwt-sft-desc.tex
+++ b/doc/mf6io/mf6ivar/tex/gwt-sft-desc.tex
@@ -47,7 +47,7 @@
 \item \textbf{Block: PACKAGEDATA}
 
 \begin{description}
-\item \texttt{rno}---integer value that defines the reach number associated with the specified PACKAGEDATA data on the line. RNO must be greater than zero and less than or equal to NREACHES. Reach information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if information for a reach is specified more than once.
+\item \texttt{ifno}---integer value that defines the feature (reach) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NREACHES. Reach information must be specified for every reach or the program will terminate with an error.  The program will also terminate with an error if information for a reach is specified more than once.
 
 \item \texttt{strt}---real value that defines the starting concentration for the reach.
 
@@ -61,7 +61,7 @@
 \begin{description}
 \item \texttt{iper}---integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block.
 
-\item \texttt{rno}---integer value that defines the reach number associated with the specified PERIOD data on the line. RNO must be greater than zero and less than or equal to NREACHES.
+\item \texttt{ifno}---integer value that defines the feature (reach) number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NREACHES.
 
 \item \texttt{reachsetting}---line of information that is parsed into a keyword and values.  Keyword values that can be used to start the REACHSETTING string include: STATUS, CONCENTRATION, RAINFALL, EVAPORATION, RUNOFF, and AUXILIARY.  These settings are used to assign the concentration of associated with the corresponding flow terms.  Concentrations cannot be specified for all flow terms.  For example, the Streamflow Package supports a ``DIVERSION'' flow term.  Diversion water will be routed using the calculated concentration of the reach.
 
diff --git a/doc/mf6io/mf6ivar/tex/gwt-sft-packagedata.dat b/doc/mf6io/mf6ivar/tex/gwt-sft-packagedata.dat
index 5176b996a98..c293a94d109 100644
--- a/doc/mf6io/mf6ivar/tex/gwt-sft-packagedata.dat
+++ b/doc/mf6io/mf6ivar/tex/gwt-sft-packagedata.dat
@@ -1,5 +1,5 @@
 BEGIN PACKAGEDATA
-  <rno> <strt> [<@aux(naux)@>] [<boundname>]
-  <rno> <strt> [<@aux(naux)@>] [<boundname>]
+  <ifno> <strt> [<@aux(naux)@>] [<boundname>]
+  <ifno> <strt> [<@aux(naux)@>] [<boundname>]
   ...
 END PACKAGEDATA
diff --git a/doc/mf6io/mf6ivar/tex/gwt-sft-period.dat b/doc/mf6io/mf6ivar/tex/gwt-sft-period.dat
index 1b56b2824e2..98ef19da015 100644
--- a/doc/mf6io/mf6ivar/tex/gwt-sft-period.dat
+++ b/doc/mf6io/mf6ivar/tex/gwt-sft-period.dat
@@ -1,5 +1,5 @@
 BEGIN PERIOD <iper>
-  <rno> <reachsetting>
-  <rno> <reachsetting>
+  <ifno> <reachsetting>
+  <ifno> <reachsetting>
   ...
 END PERIOD
diff --git a/doc/mf6io/mf6ivar/tex/gwt-ssm-desc.tex b/doc/mf6io/mf6ivar/tex/gwt-ssm-desc.tex
index 0d450f542f4..d75c8508def 100644
--- a/doc/mf6io/mf6ivar/tex/gwt-ssm-desc.tex
+++ b/doc/mf6io/mf6ivar/tex/gwt-ssm-desc.tex
@@ -13,7 +13,7 @@
 \begin{description}
 \item \texttt{pname}---name of the flow package for which an auxiliary variable contains a source concentration.  If this flow package is represented using an advanced transport package (SFT, LKT, MWT, or UZT), then the advanced transport package will override SSM terms specified here.
 
-\item \texttt{srctype}---keyword indicating how concentration will be assigned for sources and sinks.  Keyword must be specified as either AUX or AUXMIXED.  For both options the user must provide an auxiliary variable in the corresponding flow package.  The auxiliary variable must have the same name as the AUXNAME value that follows.  If the AUX keyword is specified, then the auxiliary variable specified by the user will be assigned as the concenration value for groundwater sources (flows with a positive sign).  For negative flow rates (sinks), groundwater will be withdrawn from the cell at the simulated concentration of the cell.  The AUXMIXED option provides an alternative method for how to determine the concentration of sinks.  If the cell concentration is larger than the user-specified auxiliary concentration, then the concentration of groundwater withdrawn from the cell will be assigned as the user-specified concentration.  Alternatively, if the user-specified auxiliary concentration is larger than the cell concentration, then groundwater will be withdrawn at the cell concentration.  Thus, the AUXMIXED option is designed to work with the Evapotranspiration (EVT) and Recharge (RCH) Packages where water may be withdrawn at a concentration that is less than the cell concentration.
+\item \texttt{srctype}---keyword indicating how concentration will be assigned for sources and sinks.  Keyword must be specified as either AUX or AUXMIXED.  For both options the user must provide an auxiliary variable in the corresponding flow package.  The auxiliary variable must have the same name as the AUXNAME value that follows.  If the AUX keyword is specified, then the auxiliary variable specified by the user will be assigned as the concentration value for groundwater sources (flows with a positive sign).  For negative flow rates (sinks), groundwater will be withdrawn from the cell at the simulated concentration of the cell.  The AUXMIXED option provides an alternative method for how to determine the concentration of sinks.  If the cell concentration is larger than the user-specified auxiliary concentration, then the concentration of groundwater withdrawn from the cell will be assigned as the user-specified concentration.  Alternatively, if the user-specified auxiliary concentration is larger than the cell concentration, then groundwater will be withdrawn at the cell concentration.  Thus, the AUXMIXED option is designed to work with the Evapotranspiration (EVT) and Recharge (RCH) Packages where water may be withdrawn at a concentration that is less than the cell concentration.
 
 \item \texttt{auxname}---name of the auxiliary variable in the package PNAME.  This auxiliary variable must exist and be specified by the user in that package.  The values in this auxiliary variable will be used to set the concentration associated with the flows for that boundary package.
 
diff --git a/doc/mf6io/mf6ivar/tex/gwt-uzt-desc.tex b/doc/mf6io/mf6ivar/tex/gwt-uzt-desc.tex
index aab78138481..bd53d44a933 100644
--- a/doc/mf6io/mf6ivar/tex/gwt-uzt-desc.tex
+++ b/doc/mf6io/mf6ivar/tex/gwt-uzt-desc.tex
@@ -47,7 +47,7 @@
 \item \textbf{Block: PACKAGEDATA}
 
 \begin{description}
-\item \texttt{uzfno}---integer value that defines the UZF cell number associated with the specified PACKAGEDATA data on the line. UZFNO must be greater than zero and less than or equal to NUZFCELLS. Unsaturated zone flow information must be specified for every UZF cell or the program will terminate with an error.  The program will also terminate with an error if information for a UZF cell is specified more than once.
+\item \texttt{ifno}---integer value that defines the feature (UZF object) number associated with the specified PACKAGEDATA data on the line. IFNO must be greater than zero and less than or equal to NUZFCELLS. Unsaturated zone flow information must be specified for every UZF cell or the program will terminate with an error.  The program will also terminate with an error if information for a UZF cell is specified more than once.
 
 \item \texttt{strt}---real value that defines the starting concentration for the unsaturated zone flow cell.
 
@@ -61,7 +61,7 @@
 \begin{description}
 \item \texttt{iper}---integer value specifying the starting stress period number for which the data specified in the PERIOD block apply.  IPER must be less than or equal to NPER in the TDIS Package and greater than zero.  The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block.  The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block.
 
-\item \texttt{uzfno}---integer value that defines the UZF cell number associated with the specified PERIOD data on the line. UZFNO must be greater than zero and less than or equal to NUZFCELLS.
+\item \texttt{ifno}---integer value that defines the feature (UZF object) number associated with the specified PERIOD data on the line. IFNO must be greater than zero and less than or equal to NUZFCELLS.
 
 \item \texttt{uztsetting}---line of information that is parsed into a keyword and values.  Keyword values that can be used to start the UZTSETTING string include: STATUS, CONCENTRATION, INFILTRATION, UZET, and AUXILIARY.  These settings are used to assign the concentration of associated with the corresponding flow terms.  Concentrations cannot be specified for all flow terms.
 
diff --git a/doc/mf6io/mf6ivar/tex/gwt-uzt-packagedata.dat b/doc/mf6io/mf6ivar/tex/gwt-uzt-packagedata.dat
index b6b04c298fe..c293a94d109 100644
--- a/doc/mf6io/mf6ivar/tex/gwt-uzt-packagedata.dat
+++ b/doc/mf6io/mf6ivar/tex/gwt-uzt-packagedata.dat
@@ -1,5 +1,5 @@
 BEGIN PACKAGEDATA
-  <uzfno> <strt> [<@aux(naux)@>] [<boundname>]
-  <uzfno> <strt> [<@aux(naux)@>] [<boundname>]
+  <ifno> <strt> [<@aux(naux)@>] [<boundname>]
+  <ifno> <strt> [<@aux(naux)@>] [<boundname>]
   ...
 END PACKAGEDATA
diff --git a/doc/mf6io/mf6ivar/tex/gwt-uzt-period.dat b/doc/mf6io/mf6ivar/tex/gwt-uzt-period.dat
index 8bd28bd48b9..5e1d29136c6 100644
--- a/doc/mf6io/mf6ivar/tex/gwt-uzt-period.dat
+++ b/doc/mf6io/mf6ivar/tex/gwt-uzt-period.dat
@@ -1,5 +1,5 @@
 BEGIN PERIOD <iper>
-  <uzfno> <uztsetting>
-  <uzfno> <uztsetting>
+  <ifno> <uztsetting>
+  <ifno> <uztsetting>
   ...
 END PERIOD
diff --git a/doc/mf6io/mf6ivar/tex/utl-spc-desc.tex b/doc/mf6io/mf6ivar/tex/utl-spc-desc.tex
index bba10d98e87..3e5c0ccf826 100644
--- a/doc/mf6io/mf6ivar/tex/utl-spc-desc.tex
+++ b/doc/mf6io/mf6ivar/tex/utl-spc-desc.tex
@@ -25,7 +25,7 @@
 
 \item \texttt{bndno}---integer value that defines the boundary package feature number associated with the specified PERIOD data on the line. BNDNO must be greater than zero and less than or equal to MAXBOUND.
 
-\item \texttt{spcsetting}---line of information that is parsed into a keyword and values.  Keyword values that can be used to start the MAWSETTING string include: CONCENTRATION.
+\item \texttt{spcsetting}---line of information that is parsed into a keyword and values.  Keyword values that can be used to start the SPCSETTING string include: CONCENTRATION.
 
 \begin{lstlisting}[style=blockdefinition]
 CONCENTRATION <@concentration@>
diff --git a/doc/mf6io/mf6noname.tex b/doc/mf6io/mf6noname.tex
index 2a1d08622d2..6671ddbe223 100644
--- a/doc/mf6io/mf6noname.tex
+++ b/doc/mf6io/mf6noname.tex
@@ -3,8 +3,6 @@
 
 ERROR REPORT:
 
-  1. mf6.exe: mfsim.nam is not present in working directory.
-
-
+  1. mf6: mfsim.nam is not present in working directory.
 \end{lstlisting}
 }
diff --git a/doc/mf6io/mf6output.tex b/doc/mf6io/mf6output.tex
index 6c982d2f831..a62c97b6d73 100644
--- a/doc/mf6io/mf6output.tex
+++ b/doc/mf6io/mf6output.tex
@@ -2,37 +2,33 @@
 \begin{lstlisting}[style=modeloutput]
                                    MODFLOW 6
                 U.S. GEOLOGICAL SURVEY MODULAR HYDROLOGIC MODEL
-                            VERSION 6.3.0 03/04/2022
+                  VERSION 6.5.0.dev0 (preliminary) 07/13/2023
+                               ***DEVELOP MODE***
 
-   MODFLOW 6 compiled Mar 02 2022 15:29:04 with Intel(R) Fortran Intel(R) 64
-   Compiler Classic for applications running on Intel(R) 64, Version 2021.5.0
-                             Build 20211109_000000
+        MODFLOW 6 compiled Jan 24 2024 12:12:59 with GCC version 13.2.0
 
-This software has been approved for release by the U.S. Geological
-Survey (USGS). Although the software has been subjected to rigorous
-review, the USGS reserves the right to update the software as needed
-pursuant to further analysis and review. No warranty, expressed or
-implied, is made by the USGS or the U.S. Government as to the
-functionality of the software and related material nor shall the
-fact of release constitute any such warranty. Furthermore, the
-software is released on condition that neither the USGS nor the U.S.
-Government shall be held liable for any damages resulting from its
-authorized or unauthorized use. Also refer to the USGS Water
-Resources Software User Rights Notice for complete use, copyright,
-and distribution information.
+This software is preliminary or provisional and is subject to 
+revision. It is being provided to meet the need for timely best 
+science. The software has not received final approval by the U.S. 
+Geological Survey (USGS). No warranty, expressed or implied, is made 
+by the USGS or the U.S. Government as to the functionality of the 
+software and related material nor shall the fact of release 
+constitute any such warranty. The software is provided on the 
+condition that neither the USGS nor the U.S. Government shall be held 
+liable for any damages resulting from the authorized or unauthorized 
+use of the software.
 
 
- Run start date and time (yyyy/mm/dd hh:mm:ss): 2022/03/04 12:00:35
+ Run start date and time (yyyy/mm/dd hh:mm:ss): 2024/01/24 12:13:22
 
  Writing simulation list file: mfsim.lst
  Using Simulation name file: mfsim.nam
 
     Solving:  Stress period:     1    Time step:     1
 
- Run end date and time (yyyy/mm/dd hh:mm:ss): 2022/03/04 12:00:36
- Elapsed run time:  0.156 Seconds
+ Run end date and time (yyyy/mm/dd hh:mm:ss): 2024/01/24 12:13:22
+ Elapsed run time:  0.034 Seconds
 
  Normal termination of simulation.
-
 \end{lstlisting}
 }
diff --git a/doc/mf6io/mf6switches.tex b/doc/mf6io/mf6switches.tex
index 280a969fdd6..bd204027dce 100644
--- a/doc/mf6io/mf6switches.tex
+++ b/doc/mf6io/mf6switches.tex
@@ -1,14 +1,15 @@
 {\small
 \begin{lstlisting}[style=modeloutput]
-mf6.exe - MODFLOW 6.3.0 03/04/2022 (compiled Mar 02 2022 15:29:04)
-usage: mf6.exe               run MODFLOW 6 using "mfsim.nam"
-   or: mf6.exe [options]     retrieve program information
+mf6 - MODFLOW 6.5.0.dev0 (preliminary) 07/13/2023 (compiled Jan 24 2024 12:12:59)
+usage: mf6               run MODFLOW 6 using "mfsim.nam"
+   or: mf6 [options]     retrieve program information
 
-Options   GNU long option   Meaning
+Options   GNU long option   Meaning 
  -h, -?    --help           Show this message
  -v        --version        Display program version information.
  -dev      --develop        Display program develop option mode.
  -d        --disclaimer     Display program disclaimer.
+ -p        --parallel       Run program in parallel mode.
  -lic      --license        Display program license information.
  -c        --compiler       Display compiler information.
  -co       --compiler-opt   Display compiler options.
@@ -18,19 +19,17 @@
                             <str>=debug   Enhanced output to STDOUT.
  -m <str>  --mode <str>     MODFLOW 6 simulation mode based on <str>.
                             <str>=validate Check model input for
-                                           errors but do not
-                                           assemble or solve matrix
-                                           equations or write
+                                           errors but do not 
+                                           assemble or solve matrix 
+                                           equations or write 
                                            solution output.
-
-Bug reporting and contributions are welcome from the community.
+                                                                    
+Bug reporting and contributions are welcome from the community. 
 Questions can be asked on the issues page[1]. Before creating a new
 issue, please take a moment to search and make sure a similar issue
 does not already exist. If one does exist, you can comment (most
 simply even with just :+1:) to show your support for that issue.
-
+                                                                    
 [1] https://github.com/MODFLOW-USGS/modflow6/issues
-
-
 \end{lstlisting}
 }
diff --git a/doc/version.py b/doc/version.py
index b063daa0c02..5456e79843b 100644
--- a/doc/version.py
+++ b/doc/version.py
@@ -1,10 +1,3 @@
 # MODFLOW 6 version file automatically created using...update_version.py
-# created on...June 28, 2023 19:45:12
-
-major = 6
-minor = 4
-micro = 2
-label = ''
-__version__ = '{:d}.{:d}.{:d}'.format(major, minor, micro)
-if label:
-	__version__ += '{}{}'.format(__version__, label)
\ No newline at end of file
+# created on...February 07, 2024 21:53:23
+__version__ = "6.4.3"
diff --git a/doc/version.tex b/doc/version.tex
index 6beb425516a..88c37fbb614 100644
--- a/doc/version.tex
+++ b/doc/version.tex
@@ -1,3 +1,3 @@
-\newcommand{\modflowversion}{mf6.4.2}
-\newcommand{\modflowdate}{June 28, 2023}
+\newcommand{\modflowversion}{mf6.4.3}
+\newcommand{\modflowdate}{February 07, 2024}
 \newcommand{\currentmodflowversion}{Version \modflowversion---\modflowdate}
diff --git a/environment.yml b/environment.yml
index c989e3bc197..118a816e753 100644
--- a/environment.yml
+++ b/environment.yml
@@ -5,23 +5,26 @@ channels:
   - defaults
 
 dependencies:
+  - python
   - appdirs
   - filelock
   - fprettify
+  - fortran-language-server
   - jupytext
   - matplotlib
-  - meson>=1.1.0
+  - meson=1.3.0
   - ninja
   - numpy
+  - pyshp
+  - shapely
   - pip
   - pip:
       - git+https://github.com/modflowpy/flopy.git
       - git+https://github.com/modflowpy/pymake.git
       - git+https://github.com/Deltares/xmipy.git
       - git+https://github.com/MODFLOW-USGS/modflowapi.git
-      - modflow-devtools
+      - git+https://github.com/MODFLOW-USGS/modflow-devtools.git
   - pytest
-  - pytest-cases
   - pytest-dotenv
   - pytest-order
   - pytest-xdist
diff --git a/make/makedefaults b/make/makedefaults
index 7bbd4dd3293..88e1790887a 100644
--- a/make/makedefaults
+++ b/make/makedefaults
@@ -1,4 +1,4 @@
-# makedefaults created by pymake (version 1.2.7) for the 'mf6' executable.
+# makedefaults created by pymake (version 1.2.9.dev0) for the 'mf6' executable.
 
 # determine OS
 ifeq ($(OS), Windows_NT)
@@ -57,19 +57,16 @@ OPTLEVEL ?= -O2
 # set the fortran flags
 ifeq ($(detected_OS), Windows)
 	ifeq ($(FC), gfortran)
-		FFLAGS ?= -static -fbacktrace -ffpe-summary=overflow -ffpe-trap=overflow,zero,invalid $(OS_macro) -fall-intrinsics -Wtabs -Wline-truncation -Wunused-label -Wunused-variable -pedantic -std=f2008 -Wcharacter-truncation -cpp
+		FFLAGS ?= -static -fbacktrace -ffpe-summary=overflow -ffpe-trap=overflow,zero,invalid -fall-intrinsics -pedantic -Wcharacter-truncation $(OS_macro) -Wtabs -Wline-truncation -Wunused-label -Wunused-variable -std=f2008 -cpp
 	endif
 else
 	ifeq ($(FC), gfortran)
-		FFLAGS ?= -fbacktrace -ffpe-summary=overflow -ffpe-trap=overflow,zero,invalid $(OS_macro) -fall-intrinsics -Wtabs -Wline-truncation -Wunused-label -Wunused-variable -pedantic -std=f2008 -Wcharacter-truncation -cpp
+		FFLAGS ?= -fbacktrace -ffpe-summary=overflow -ffpe-trap=overflow,zero,invalid -fall-intrinsics -pedantic -Wcharacter-truncation $(OS_macro) -Wtabs -Wline-truncation -Wunused-label -Wunused-variable -std=f2008 -cpp
 	endif
 	ifeq ($(FC), $(filter $(FC), ifort mpiifort))
-		FFLAGS ?= -no-heap-arrays -fpe0 -traceback -fpp
+		FFLAGS ?= -no-heap-arrays -fpe0 -traceback -Qdiag-disable:7416 -Qdiag-disable:7025 -Qdiag-disable:5268 -fpp
 		MODSWITCH = -module $(MODDIR)
 	endif
-	ifeq ($(FC), $(filter $(FC), ftn))
-		FFLAGS ?= -h noheap_allocate
-	endif
 endif
 
 # set the ldflgs
@@ -84,9 +81,6 @@ else
 	ifeq ($(FC), $(filter $(FC), ifort mpiifort))
 		LDFLAGS ?= -lc
 	endif
-	ifeq ($(FC), $(filter $(FC), ftn))
-		LDFLAGS ?= -lc
-	endif
 endif
 
 # check for Windows error condition
diff --git a/make/makefile b/make/makefile
index 552d7c70a1d..885d0663ab9 100644
--- a/make/makefile
+++ b/make/makefile
@@ -1,4 +1,4 @@
-# makefile created by pymake (version 1.2.7) for the 'mf6' executable.
+# makefile created by pymake (version 1.2.9.dev0) for the 'mf6' executable.
 
 
 include ./makedefaults
@@ -6,34 +6,35 @@ include ./makedefaults
 # Define the source file directories
 SOURCEDIR1=../src
 SOURCEDIR2=../src/Exchange
-SOURCEDIR3=../src/Distributed
-SOURCEDIR4=../src/Solution
-SOURCEDIR5=../src/Solution/LinearMethods
-SOURCEDIR6=../src/Solution/PETSc
-SOURCEDIR7=../src/Timing
-SOURCEDIR8=../src/Utilities
-SOURCEDIR9=../src/Utilities/Idm
-SOURCEDIR10=../src/Utilities/Idm/selector
-SOURCEDIR11=../src/Utilities/Idm/mf6blockfile
-SOURCEDIR12=../src/Utilities/TimeSeries
-SOURCEDIR13=../src/Utilities/Memory
-SOURCEDIR14=../src/Utilities/OutputControl
-SOURCEDIR15=../src/Utilities/ArrayRead
-SOURCEDIR16=../src/Utilities/Libraries
-SOURCEDIR17=../src/Utilities/Libraries/rcm
-SOURCEDIR18=../src/Utilities/Libraries/blas
-SOURCEDIR19=../src/Utilities/Libraries/sparskit2
-SOURCEDIR20=../src/Utilities/Libraries/daglib
-SOURCEDIR21=../src/Utilities/Libraries/sparsekit
-SOURCEDIR22=../src/Utilities/Vector
-SOURCEDIR23=../src/Utilities/Matrix
-SOURCEDIR24=../src/Utilities/Observation
-SOURCEDIR25=../src/Model
-SOURCEDIR26=../src/Model/Connection
-SOURCEDIR27=../src/Model/GroundWaterTransport
-SOURCEDIR28=../src/Model/ModelUtilities
-SOURCEDIR29=../src/Model/GroundWaterFlow
-SOURCEDIR30=../src/Model/Geometry
+SOURCEDIR3=../src/Model
+SOURCEDIR4=../src/Model/Geometry
+SOURCEDIR5=../src/Model/TransportModel
+SOURCEDIR6=../src/Model/ModelUtilities
+SOURCEDIR7=../src/Model/Connection
+SOURCEDIR8=../src/Model/GroundWaterTransport
+SOURCEDIR9=../src/Model/GroundWaterFlow
+SOURCEDIR10=../src/Distributed
+SOURCEDIR11=../src/Solution
+SOURCEDIR12=../src/Solution/PETSc
+SOURCEDIR13=../src/Solution/LinearMethods
+SOURCEDIR14=../src/Timing
+SOURCEDIR15=../src/Utilities
+SOURCEDIR16=../src/Utilities/TimeSeries
+SOURCEDIR17=../src/Utilities/Libraries
+SOURCEDIR18=../src/Utilities/Libraries/rcm
+SOURCEDIR19=../src/Utilities/Libraries/sparsekit
+SOURCEDIR20=../src/Utilities/Libraries/sparskit2
+SOURCEDIR21=../src/Utilities/Libraries/blas
+SOURCEDIR22=../src/Utilities/Libraries/daglib
+SOURCEDIR23=../src/Utilities/Idm
+SOURCEDIR24=../src/Utilities/Idm/selector
+SOURCEDIR25=../src/Utilities/Idm/mf6blockfile
+SOURCEDIR26=../src/Utilities/Matrix
+SOURCEDIR27=../src/Utilities/Vector
+SOURCEDIR28=../src/Utilities/Observation
+SOURCEDIR29=../src/Utilities/OutputControl
+SOURCEDIR30=../src/Utilities/Memory
+SOURCEDIR31=../src/Utilities/ArrayRead
 
 VPATH = \
 ${SOURCEDIR1} \
@@ -65,20 +66,21 @@ ${SOURCEDIR26} \
 ${SOURCEDIR27} \
 ${SOURCEDIR28} \
 ${SOURCEDIR29} \
-${SOURCEDIR30} 
+${SOURCEDIR30} \
+${SOURCEDIR31} 
 
 .SUFFIXES: .f90 .F90 .o
 
 OBJECTS = \
 $(OBJDIR)/kind.o \
 $(OBJDIR)/Constants.o \
+$(OBJDIR)/ErrorUtil.o \
 $(OBJDIR)/SimVariables.o \
-$(OBJDIR)/genericutils.o \
+$(OBJDIR)/ArrayHandlers.o \
+$(OBJDIR)/Message.o \
 $(OBJDIR)/defmacro.o \
 $(OBJDIR)/compilerversion.o \
-$(OBJDIR)/ArrayHandlers.o \
 $(OBJDIR)/version.o \
-$(OBJDIR)/Message.o \
 $(OBJDIR)/Sim.o \
 $(OBJDIR)/OpenSpec.o \
 $(OBJDIR)/InputOutput.o \
@@ -88,12 +90,16 @@ $(OBJDIR)/MemoryHelper.o \
 $(OBJDIR)/CharString.o \
 $(OBJDIR)/Memory.o \
 $(OBJDIR)/List.o \
+$(OBJDIR)/LongLineReader.o \
+$(OBJDIR)/DevFeature.o \
 $(OBJDIR)/MemoryList.o \
 $(OBJDIR)/TimeSeriesRecord.o \
+$(OBJDIR)/MathUtil.o \
 $(OBJDIR)/BlockParser.o \
 $(OBJDIR)/MemoryManager.o \
 $(OBJDIR)/TimeSeries.o \
 $(OBJDIR)/ats.o \
+$(OBJDIR)/GeomUtil.o \
 $(OBJDIR)/TimeSeriesLink.o \
 $(OBJDIR)/TimeSeriesFileList.o \
 $(OBJDIR)/tdis.o \
@@ -104,60 +110,79 @@ $(OBJDIR)/DisvGeom.o \
 $(OBJDIR)/ArrayReaders.o \
 $(OBJDIR)/TimeSeriesManager.o \
 $(OBJDIR)/SmoothingFunctions.o \
+$(OBJDIR)/MemoryManagerExt.o \
 $(OBJDIR)/MatrixBase.o \
 $(OBJDIR)/ListReader.o \
 $(OBJDIR)/Connections.o \
-$(OBJDIR)/DiscretizationBase.o \
+$(OBJDIR)/InputDefinition.o \
 $(OBJDIR)/TimeArray.o \
 $(OBJDIR)/ObsOutput.o \
+$(OBJDIR)/DiscretizationBase.o \
+$(OBJDIR)/simnamidm.o \
+$(OBJDIR)/gwt1idm.o \
+$(OBJDIR)/gwt1ic1idm.o \
+$(OBJDIR)/gwt1dsp1idm.o \
+$(OBJDIR)/gwt1disv1idm.o \
+$(OBJDIR)/gwt1disu1idm.o \
+$(OBJDIR)/gwt1dis1idm.o \
+$(OBJDIR)/gwt1cnc1idm.o \
+$(OBJDIR)/gwf3wel8idm.o \
+$(OBJDIR)/gwf3riv8idm.o \
+$(OBJDIR)/gwf3rch8idm.o \
+$(OBJDIR)/gwf3rcha8idm.o \
+$(OBJDIR)/gwf3npf8idm.o \
+$(OBJDIR)/gwf3idm.o \
+$(OBJDIR)/gwf3ic8idm.o \
+$(OBJDIR)/gwf3ghb8idm.o \
+$(OBJDIR)/gwf3evt8idm.o \
+$(OBJDIR)/gwf3evta8idm.o \
+$(OBJDIR)/gwf3drn8idm.o \
+$(OBJDIR)/gwf3disv8idm.o \
+$(OBJDIR)/gwf3disu8idm.o \
+$(OBJDIR)/gwf3dis8idm.o \
+$(OBJDIR)/gwf3chd8idm.o \
+$(OBJDIR)/gwtgwtidm.o \
+$(OBJDIR)/gwfgwtidm.o \
+$(OBJDIR)/gwfgwfidm.o \
 $(OBJDIR)/TimeArraySeries.o \
 $(OBJDIR)/ObsOutputList.o \
 $(OBJDIR)/Observe.o \
+$(OBJDIR)/IdmSimDfnSelector.o \
+$(OBJDIR)/IdmGwtDfnSelector.o \
+$(OBJDIR)/IdmGwfDfnSelector.o \
+$(OBJDIR)/IdmExgDfnSelector.o \
 $(OBJDIR)/TimeArraySeriesLink.o \
 $(OBJDIR)/ObsUtility.o \
 $(OBJDIR)/ObsContainer.o \
 $(OBJDIR)/BudgetFileReader.o \
+$(OBJDIR)/IdmDfnSelector.o \
 $(OBJDIR)/TimeArraySeriesManager.o \
 $(OBJDIR)/PackageMover.o \
 $(OBJDIR)/Obs3.o \
 $(OBJDIR)/NumericalPackage.o \
 $(OBJDIR)/Budget.o \
-$(OBJDIR)/SeqVector.o \
+$(OBJDIR)/BudgetTerm.o \
 $(OBJDIR)/sort.o \
 $(OBJDIR)/SfrCrossSectionUtils.o \
-$(OBJDIR)/BudgetTerm.o \
+$(OBJDIR)/SourceCommon.o \
 $(OBJDIR)/BoundaryPackage.o \
-$(OBJDIR)/BaseModel.o \
-$(OBJDIR)/SparseMatrix.o \
-$(OBJDIR)/LinearSolverBase.o \
-$(OBJDIR)/ims8reordering.o \
 $(OBJDIR)/VirtualBase.o \
 $(OBJDIR)/STLVecInt.o \
-$(OBJDIR)/InputDefinition.o \
+$(OBJDIR)/BaseModel.o \
+$(OBJDIR)/PackageBudget.o \
+$(OBJDIR)/HeadFileReader.o \
+$(OBJDIR)/BudgetObject.o \
+$(OBJDIR)/PrintSaveManager.o \
 $(OBJDIR)/SfrCrossSectionManager.o \
 $(OBJDIR)/dag_module.o \
-$(OBJDIR)/BudgetObject.o \
-$(OBJDIR)/NumericalModel.o \
-$(OBJDIR)/BaseExchange.o \
-$(OBJDIR)/ImsLinearSolver.o \
-$(OBJDIR)/ims8base.o \
+$(OBJDIR)/BoundaryPackageExt.o \
 $(OBJDIR)/VirtualDataLists.o \
 $(OBJDIR)/VirtualDataContainer.o \
 $(OBJDIR)/SimStages.o \
-$(OBJDIR)/simnamidm.o \
-$(OBJDIR)/gwt1idm.o \
-$(OBJDIR)/gwt1dsp1idm.o \
-$(OBJDIR)/gwt1disv1idm.o \
-$(OBJDIR)/gwt1disu1idm.o \
-$(OBJDIR)/gwt1dis1idm.o \
-$(OBJDIR)/gwf3npf8idm.o \
-$(OBJDIR)/gwf3idm.o \
-$(OBJDIR)/gwf3disv8idm.o \
-$(OBJDIR)/gwf3disu8idm.o \
-$(OBJDIR)/gwf3dis8idm.o \
-$(OBJDIR)/PackageBudget.o \
-$(OBJDIR)/HeadFileReader.o \
-$(OBJDIR)/PrintSaveManager.o \
+$(OBJDIR)/NumericalModel.o \
+$(OBJDIR)/FlowModelInterface.o \
+$(OBJDIR)/OutputControlData.o \
+$(OBJDIR)/gwf3ic8.o \
 $(OBJDIR)/Xt3dAlgorithm.o \
 $(OBJDIR)/gwf3tvbase8.o \
 $(OBJDIR)/gwf3sfr8.o \
@@ -168,38 +193,39 @@ $(OBJDIR)/gwf3lak8.o \
 $(OBJDIR)/GwfVscInputData.o \
 $(OBJDIR)/gwf3ghb8.o \
 $(OBJDIR)/gwf3drn8.o \
-$(OBJDIR)/Timer.o \
-$(OBJDIR)/NumericalExchange.o \
-$(OBJDIR)/LinearSolverFactory.o \
-$(OBJDIR)/ims8linear.o \
-$(OBJDIR)/BaseSolution.o \
 $(OBJDIR)/IndexMap.o \
 $(OBJDIR)/VirtualModel.o \
-$(OBJDIR)/IdmSimDfnSelector.o \
-$(OBJDIR)/IdmGwtDfnSelector.o \
-$(OBJDIR)/IdmGwfDfnSelector.o \
+$(OBJDIR)/BaseExchange.o \
+$(OBJDIR)/tsp1fmi1.o \
+$(OBJDIR)/GwtSpc.o \
+$(OBJDIR)/OutputControl.o \
+$(OBJDIR)/tsp1ic1.o \
+$(OBJDIR)/TspAdvOptions.o \
 $(OBJDIR)/UzfCellGroup.o \
-$(OBJDIR)/gwt1fmi1.o \
-$(OBJDIR)/OutputControlData.o \
-$(OBJDIR)/gwf3ic8.o \
 $(OBJDIR)/Xt3dInterface.o \
 $(OBJDIR)/gwf3tvk8.o \
-$(OBJDIR)/MemoryManagerExt.o \
 $(OBJDIR)/gwf3vsc8.o \
 $(OBJDIR)/GwfNpfOptions.o \
-$(OBJDIR)/NumericalSolution.o \
 $(OBJDIR)/InterfaceMap.o \
+$(OBJDIR)/SeqVector.o \
+$(OBJDIR)/ImsLinearSettings.o \
+$(OBJDIR)/ConvergenceSummary.o \
+$(OBJDIR)/ArrayReaderBase.o \
 $(OBJDIR)/CellWithNbrs.o \
-$(OBJDIR)/IdmDfnSelector.o \
+$(OBJDIR)/NumericalExchange.o \
+$(OBJDIR)/tsp1ssm1.o \
+$(OBJDIR)/tsp1oc1.o \
+$(OBJDIR)/tsp1obs1.o \
+$(OBJDIR)/tsp1mvt1.o \
+$(OBJDIR)/tsp1adv1.o \
+$(OBJDIR)/gwf3disv8.o \
+$(OBJDIR)/gwf3disu8.o \
+$(OBJDIR)/gwf3dis8.o \
 $(OBJDIR)/gwf3uzf8.o \
-$(OBJDIR)/gwt1apt1.o \
-$(OBJDIR)/GwtSpc.o \
-$(OBJDIR)/OutputControl.o \
-$(OBJDIR)/gwt1ic1.o \
+$(OBJDIR)/tsp1apt1.o \
 $(OBJDIR)/gwt1mst1.o \
 $(OBJDIR)/GwtDspOptions.o \
 $(OBJDIR)/gwf3npf8.o \
-$(OBJDIR)/GwtAdvOptions.o \
 $(OBJDIR)/gwf3tvs8.o \
 $(OBJDIR)/GwfStorageUtils.o \
 $(OBJDIR)/Mover.o \
@@ -207,29 +233,24 @@ $(OBJDIR)/GwfMvrPeriodData.o \
 $(OBJDIR)/ims8misc.o \
 $(OBJDIR)/GwfBuyInputData.o \
 $(OBJDIR)/VirtualSolution.o \
-$(OBJDIR)/ArrayReaderBase.o \
+$(OBJDIR)/SparseMatrix.o \
+$(OBJDIR)/LinearSolverBase.o \
+$(OBJDIR)/ims8reordering.o \
+$(OBJDIR)/ModflowInput.o \
+$(OBJDIR)/Integer2dReader.o \
 $(OBJDIR)/VirtualExchange.o \
-$(OBJDIR)/gwf3disu8.o \
 $(OBJDIR)/GridSorting.o \
 $(OBJDIR)/DisConnExchange.o \
 $(OBJDIR)/CsrUtils.o \
-$(OBJDIR)/TransportModel.o \
-$(OBJDIR)/ModelPackageInputs.o \
+$(OBJDIR)/tsp1.o \
 $(OBJDIR)/gwt1uzt1.o \
-$(OBJDIR)/gwt1ssm1.o \
 $(OBJDIR)/gwt1src1.o \
 $(OBJDIR)/gwt1sft1.o \
-$(OBJDIR)/gwt1oc1.o \
-$(OBJDIR)/gwt1obs1.o \
 $(OBJDIR)/gwt1mwt1.o \
-$(OBJDIR)/gwt1mvt1.o \
 $(OBJDIR)/gwt1lkt1.o \
 $(OBJDIR)/gwt1ist1.o \
 $(OBJDIR)/gwt1dsp1.o \
 $(OBJDIR)/gwt1cnc1.o \
-$(OBJDIR)/gwt1adv1.o \
-$(OBJDIR)/gwf3disv8.o \
-$(OBJDIR)/gwf3dis8.o \
 $(OBJDIR)/gwf3api8.o \
 $(OBJDIR)/gwf3wel8.o \
 $(OBJDIR)/gwf3rch8.o \
@@ -244,17 +265,29 @@ $(OBJDIR)/GhostNode.o \
 $(OBJDIR)/gwf3evt8.o \
 $(OBJDIR)/gwf3chd8.o \
 $(OBJDIR)/RouterBase.o \
-$(OBJDIR)/Integer2dReader.o \
-$(OBJDIR)/GridConnection.o \
-$(OBJDIR)/DistributedVariable.o \
-$(OBJDIR)/gwt1.o \
-$(OBJDIR)/gwf3.o \
-$(OBJDIR)/SerialRouter.o \
+$(OBJDIR)/ImsLinearSolver.o \
+$(OBJDIR)/ims8base.o \
 $(OBJDIR)/StructVector.o \
 $(OBJDIR)/IdmLogger.o \
+$(OBJDIR)/DefinitionSelect.o \
+$(OBJDIR)/InputLoadType.o \
 $(OBJDIR)/Integer1dReader.o \
 $(OBJDIR)/Double2dReader.o \
 $(OBJDIR)/Double1dReader.o \
+$(OBJDIR)/GridConnection.o \
+$(OBJDIR)/DistributedVariable.o \
+$(OBJDIR)/gwt1.o \
+$(OBJDIR)/gwf3.o \
+$(OBJDIR)/GwfExchangeMover.o \
+$(OBJDIR)/SerialRouter.o \
+$(OBJDIR)/Timer.o \
+$(OBJDIR)/LinearSolverFactory.o \
+$(OBJDIR)/ims8linear.o \
+$(OBJDIR)/BaseSolution.o \
+$(OBJDIR)/StructArray.o \
+$(OBJDIR)/BoundInputContext.o \
+$(OBJDIR)/AsciiInputLoadType.o \
+$(OBJDIR)/LayeredArrayReader.o \
 $(OBJDIR)/ExplicitModel.o \
 $(OBJDIR)/SpatialModelConnection.o \
 $(OBJDIR)/GwtInterfaceModel.o \
@@ -262,17 +295,18 @@ $(OBJDIR)/GwtGwtExchange.o \
 $(OBJDIR)/GwfInterfaceModel.o \
 $(OBJDIR)/GwfGwfExchange.o \
 $(OBJDIR)/RouterFactory.o \
+$(OBJDIR)/NumericalSolution.o \
 $(OBJDIR)/MappedMemory.o \
-$(OBJDIR)/StructArray.o \
-$(OBJDIR)/ModflowInput.o \
-$(OBJDIR)/LayeredArrayReader.o \
-$(OBJDIR)/DefinitionSelect.o \
+$(OBJDIR)/StressListInput.o \
+$(OBJDIR)/StressGridInput.o \
+$(OBJDIR)/LoadMf6File.o \
 $(OBJDIR)/ExplicitSolution.o \
 $(OBJDIR)/GwtGwtConnection.o \
 $(OBJDIR)/GwfGwfConnection.o \
 $(OBJDIR)/VirtualDataManager.o \
 $(OBJDIR)/Mapper.o \
-$(OBJDIR)/LoadMf6File.o \
+$(OBJDIR)/IdmMf6File.o \
+$(OBJDIR)/ModelPackageInput.o \
 $(OBJDIR)/VirtualGwtModel.o \
 $(OBJDIR)/VirtualGwtExchange.o \
 $(OBJDIR)/VirtualGwfModel.o \
@@ -281,10 +315,11 @@ $(OBJDIR)/SolutionGroup.o \
 $(OBJDIR)/SolutionFactory.o \
 $(OBJDIR)/GwfGwtExchange.o \
 $(OBJDIR)/RunControl.o \
-$(OBJDIR)/IdmMf6File.o \
+$(OBJDIR)/SourceLoad.o \
+$(OBJDIR)/ModelPackageInputs.o \
 $(OBJDIR)/SimulationCreate.o \
 $(OBJDIR)/RunControlFactory.o \
-$(OBJDIR)/IdmSimulation.o \
+$(OBJDIR)/IdmLoad.o \
 $(OBJDIR)/ConnectionBuilder.o \
 $(OBJDIR)/comarg.o \
 $(OBJDIR)/mf6core.o \
diff --git a/meson.build b/meson.build
index faf8bd2185e..f1bca2b04f0 100644
--- a/meson.build
+++ b/meson.build
@@ -1,7 +1,7 @@
 project(
   'MODFLOW 6',
   'fortran',
-  version: '6.4.2',
+  version: '6.4.3',
   license: 'CC0',
   meson_version: '>= 1.1.0',
   default_options : [
@@ -25,6 +25,7 @@ message('The used profile is:', profile)
 # parse compiler options
 fc = meson.get_compiler('fortran')
 fc_id = fc.get_id()
+message('The fc_id is:', fc_id)
 compile_args = []
 link_args = []
 
@@ -41,7 +42,7 @@ if fc_id == 'gcc'
                    '-Wno-maybe-uninitialized',   # "Uninitialized" flags produce false positives with allocatables
                    '-Wno-uninitialized',
                    ]
-
+  
   # Options specific to profile
   if profile == 'release'
     compile_args += ['-ffpe-summary=overflow', '-ffpe-trap=overflow,zero,invalid']
@@ -85,18 +86,36 @@ elif fc_id == 'intel'
                    '-diag-disable:5268',  # Line too long
                   ]
   link_args += '-static-intel'
-endif
+  
+# Command line options for ifx
+elif fc_id == 'intel-llvm-cl'
+  # windows
+  compile_args += ['/fpe:0',              # Activate all floating point exceptions
+                   '/heap-arrays:0',
+                   '/traceback',
+                   '/fpp',                # Activate preprocessing
+                   '/Qdiag-disable:7416', # f2008 warning
+                   '/Qdiag-disable:7025', # f2008 warning
+                   '/Qdiag-disable:5268', # Line too long
+                  ]
+  link_args += ['/ignore:4217', # access through ddlimport might be inefficient
+                '/ignore:4286'  # same as 4217, but more general
+               ]
 
+endif
 
 # parallel build options
-is_parallel_build = get_option('parallel')
+is_extended_build = get_option('extended')
 is_cray = get_option('cray')
 is_mpich = get_option('mpich')
 if is_cray and build_machine.system() != 'linux'
   error('cray=true only supported on linux systems')
 endif
-if is_cray and not is_parallel_build
-  is_parallel_build = true
+if not is_extended_build
+ is_extended_build = get_option('parallel')
+endif
+if is_cray and not is_extended_build
+  is_extended_build = true
   is_mpich = true
 endif
 if is_mpich
@@ -106,14 +125,14 @@ if is_mpich
     mpifort_name = 'mpichfort'
   endif
 endif
-message('Parallel build:', is_parallel_build)
+message('Extended build:', is_extended_build)
 
 # windows options for petsc
 petsc_dir = meson.project_source_root() / '..' /'petsc-3.18.5'
 petsc_arch = 'arch-ci-mswin-intel-modflow6'
 
 # on windows only with intel
-if build_machine.system() == 'windows' and is_parallel_build
+if build_machine.system() == 'windows' and is_extended_build
   if fc_id != 'intel-cl'
     error('Parallel build on Windows only with intel compiler. Terminating...')
   endif
@@ -123,8 +142,8 @@ endif
 dependencies = [ ]
 extra_cmp_args = [ ]
 
-# load petsc and mpi dependencies/libraries
-if is_parallel_build
+# load petsc, mpi, and netcdf dependencies/libraries
+if is_extended_build
   # find petsc
   if build_machine.system() != 'windows'
     petsc = dependency('PETSc', required : true)
@@ -139,16 +158,31 @@ if is_parallel_build
 
   # find mpi
   if is_mpich
-    mpi = dependency('mpich', required : true)
-    mpifort = dependency(mpifort_name, required : mpi.found())
-    dependencies += [ mpi, mpifort ]
+    mpifort = dependency(mpifort_name, required : true)
+    dependencies += mpifort
   else
     mpi = dependency('mpi', language : 'fortran', required : true)
     dependencies += mpi
   endif
   extra_cmp_args += [ '-D__WITH_MPI__']
   with_mpi = true
+
+  # find netcdf
+  if build_machine.system() != 'windows'
+    netcdf = dependency('netcdf', language : 'fortran', required : false)
+  else
+    # For CI testing only; Windows not yet supported
+    nc_dir = meson.project_source_root() / '..' / 'ncf' / 'netcdf-fortran-4.6.1' / 'fortran'
+    netcdf = fc.find_library('netcdff', dirs: [ nc_dir ], required : false, static : false)
+    #nc_incdir = include_directories([ nc_dir ])
+  endif
+  if netcdf.found()
+    with_netcdf = true
+    extra_cmp_args += [ '-D__WITH_NETCDF__' ]
+    dependencies += [ netcdf ]    
+  endif
 else
+  with_netcdf = false
   with_petsc = false
   with_mpi = false
 endif
@@ -158,7 +192,7 @@ compile_args += extra_cmp_args
 add_project_arguments(fc.get_supported_arguments(compile_args), language: 'fortran')
 add_project_link_arguments(fc.get_supported_arguments(link_args), language: 'fortran')
 
-if is_parallel_build and build_machine.system() == 'windows'
+if is_extended_build and build_machine.system() == 'windows'
   message('Compiling PETSc Fortran modules')
   petsc_incdir = include_directories([petsc_dir / 'include', petsc_compiled / 'include'])
   petsc_src = petsc_dir / 'src'
@@ -190,8 +224,11 @@ subdir('srcbmi')
 # build zbud6 and mf5to6 utility programs
 subdir('utils')
 
-# add unit test directory
-# subdir('unittests')
+# add autotest directory
+fs = import('fs')
+if fs.is_dir('autotest')
+  subdir('autotest')
+endif
 
 # meson tests to evaluate installation success
 testdir = meson.project_source_root() / '.mf6minsim'
diff --git a/meson.options b/meson.options
index 1ac66580078..72fba261951 100644
--- a/meson.options
+++ b/meson.options
@@ -1,4 +1,5 @@
-option('parallel', type : 'boolean', value : false, description : 'Parallel build')
+option('extended', type : 'boolean', value : false, description : 'Extended build with external libraries')
+option('parallel', type : 'boolean', value : false, description : 'Extended parallel build')
 option('mpich', type : 'boolean', value : false, description : 'Use MPICH version of MPI')
-option('cray', type : 'boolean', value : false, description : 'Parallel build on CRAY with MPICH')
+option('cray', type : 'boolean', value : false, description : 'Extended build on CRAY with MPICH')
 option('buildname', type : 'string', value : 'mf6', description : 'Optional build name')
diff --git a/msvs/mf6core.vfproj b/msvs/mf6core.vfproj
index e2be9f2e7b6..04ba48ba0dd 100644
--- a/msvs/mf6core.vfproj
+++ b/msvs/mf6core.vfproj
@@ -95,9 +95,13 @@
 		<File RelativePath="..\src\Exchange\BaseExchange.f90"/>
 		<File RelativePath="..\src\Exchange\DisConnExchange.f90"/>
 		<File RelativePath="..\src\Exchange\GhostNode.f90"/>
+		<File RelativePath="..\src\Exchange\GwfExchangeMover.f90"/>
 		<File RelativePath="..\src\Exchange\GwfGwfExchange.f90"/>
+		<File RelativePath="..\src\Exchange\gwfgwfidm.f90"/>
 		<File RelativePath="..\src\Exchange\GwfGwtExchange.f90"/>
+		<File RelativePath="..\src\Exchange\gwfgwtidm.f90"/>
 		<File RelativePath="..\src\Exchange\GwtGwtExchange.f90"/>
+		<File RelativePath="..\src\Exchange\gwtgwtidm.f90"/>
 		<File RelativePath="..\src\Exchange\NumericalExchange.f90"/></Filter>
 		<Filter Name="Model">
 		<Filter Name="Connection">
@@ -122,6 +126,7 @@
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3api8.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3buy8.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3chd8.f90"/>
+		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3chd8idm.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3csub8.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3dis8.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3dis8idm.f90"/>
@@ -130,10 +135,15 @@
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3disv8.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3disv8idm.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3drn8.f90"/>
+		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3drn8idm.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3evt8.f90"/>
+		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3evt8idm.f90"/>
+		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3evta8idm.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3ghb8.f90"/>
+		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3ghb8idm.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3hfb8.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3ic8.f90"/>
+		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3ic8idm.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3idm.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3lak8.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3maw8.f90"/>
@@ -143,7 +153,10 @@
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3obs8.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3oc8.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3rch8.f90"/>
+		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3rch8idm.f90"/>
+		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3rcha8idm.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3riv8.f90"/>
+		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3riv8idm.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3sfr8.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3sto8.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3tvbase8.f90"/>
@@ -151,62 +164,70 @@
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3tvs8.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3uzf8.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3vsc8.f90"/>
-		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3wel8.f90"/></Filter>
+		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3wel8.f90"/>
+		<File RelativePath="..\src\Model\GroundWaterFlow\gwf3wel8idm.f90"/></Filter>
 		<Filter Name="GroundWaterTransport">
 		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1.f90"/>
-		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1adv1.f90"/>
-		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1apt1.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1cnc1.f90"/>
+		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1cnc1idm.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1dis1idm.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1disu1idm.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1disv1idm.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1dsp1.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1dsp1idm.f90"/>
-		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1fmi1.f90"/>
-		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1ic1.f90"/>
+		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1ic1idm.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1idm.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1ist1.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1lkt1.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1mst1.f90"/>
-		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1mvt1.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1mwt1.f90"/>
-		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1obs1.f90"/>
-		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1oc1.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1sft1.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1src1.f90"/>
-		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1ssm1.f90"/>
 		<File RelativePath="..\src\Model\GroundWaterTransport\gwt1uzt1.f90"/></Filter>
 		<Filter Name="ModelUtilities">
 		<File RelativePath="..\src\Model\ModelUtilities\BoundaryPackage.f90"/>
+		<File RelativePath="..\src\Model\ModelUtilities\BoundaryPackageExt.f90"/>
 		<File RelativePath="..\src\Model\ModelUtilities\Connections.f90"/>
 		<File RelativePath="..\src\Model\ModelUtilities\DiscretizationBase.f90"/>
 		<File RelativePath="..\src\Model\ModelUtilities\DisvGeom.f90"/>
+		<File RelativePath="..\src\Model\ModelUtilities\FlowModelInterface.f90"/>
 		<File RelativePath="..\src\Model\ModelUtilities\GwfBuyInputData.f90"/>
 		<File RelativePath="..\src\Model\ModelUtilities\GwfMvrPeriodData.f90"/>
 		<File RelativePath="..\src\Model\ModelUtilities\GwfNpfOptions.f90"/>
 		<File RelativePath="..\src\Model\ModelUtilities\GwfStorageUtils.f90"/>
 		<File RelativePath="..\src\Model\ModelUtilities\GwfVscInputData.f90"/>
-		<File RelativePath="..\src\Model\ModelUtilities\GwtAdvOptions.f90"/>
 		<File RelativePath="..\src\Model\ModelUtilities\GwtDspOptions.f90"/>
 		<File RelativePath="..\src\Model\ModelUtilities\GwtSpc.f90"/>
+		<File RelativePath="..\src\Model\ModelUtilities\ModelPackageInput.f90"/>
 		<File RelativePath="..\src\Model\ModelUtilities\Mover.f90"/>
 		<File RelativePath="..\src\Model\ModelUtilities\PackageMover.f90"/>
 		<File RelativePath="..\src\Model\ModelUtilities\SfrCrossSectionManager.f90"/>
 		<File RelativePath="..\src\Model\ModelUtilities\SfrCrossSectionUtils.f90"/>
+		<File RelativePath="..\src\Model\ModelUtilities\TspAdvOptions.f90"/>
 		<File RelativePath="..\src\Model\ModelUtilities\UzfCellGroup.f90"/>
 		<File RelativePath="..\src\Model\ModelUtilities\Xt3dAlgorithm.f90"/>
 		<File RelativePath="..\src\Model\ModelUtilities\Xt3dInterface.f90"/></Filter>
+		<Filter Name="TransportModel">
+		<File RelativePath="..\src\Model\TransportModel\tsp1.f90"/>
+		<File RelativePath="..\src\Model\TransportModel\tsp1adv1.f90"/>
+		<File RelativePath="..\src\Model\TransportModel\tsp1apt1.f90"/>
+		<File RelativePath="..\src\Model\TransportModel\tsp1fmi1.f90"/>
+		<File RelativePath="..\src\Model\TransportModel\tsp1ic1.f90"/>
+		<File RelativePath="..\src\Model\TransportModel\tsp1mvt1.f90"/>
+		<File RelativePath="..\src\Model\TransportModel\tsp1obs1.f90"/>
+		<File RelativePath="..\src\Model\TransportModel\tsp1oc1.f90"/>
+		<File RelativePath="..\src\Model\TransportModel\tsp1ssm1.f90"/></Filter>
 		<File RelativePath="..\src\Model\BaseModel.f90"/>
 		<File RelativePath="..\src\Model\ExplicitModel.f90"/>
 		<File RelativePath="..\src\Model\NumericalModel.f90"/>
-		<File RelativePath="..\src\Model\NumericalPackage.f90"/>
-		<File RelativePath="..\src\Model\TransportModel.f90"/></Filter>
+		<File RelativePath="..\src\Model\NumericalPackage.f90"/></Filter>
 		<Filter Name="Solution">
 		<Filter Name="LinearMethods">
 		<File RelativePath="..\src\Solution\LinearMethods\ims8base.f90"/>
 		<File RelativePath="..\src\Solution\LinearMethods\ims8linear.f90"/>
 		<File RelativePath="..\src\Solution\LinearMethods\ims8misc.f90"/>
 		<File RelativePath="..\src\Solution\LinearMethods\ims8reordering.f90"/>
+		<File RelativePath="..\src\Solution\LinearMethods\ImsLinearSettings.f90"/>
 		<File RelativePath="..\src\Solution\LinearMethods\ImsLinearSolver.f90"/></Filter>
 		<Filter Name="PETSc">
 		<File RelativePath="..\src\Solution\PETSc\PetscConvergence.F90">
@@ -214,12 +235,18 @@
 			<FileConfiguration Name="Release|x64" ExcludedFromBuild="true"/>
 			<FileConfiguration Name="Debug|x64" ExcludedFromBuild="true"/>
 			<FileConfiguration Name="Release|Win32" ExcludedFromBuild="true"/></File>
+		<File RelativePath="..\src\Solution\PETSc\PetscImsPreconditioner.F90">
+			<FileConfiguration Name="Debug|Win32" ExcludedFromBuild="true"/>
+			<FileConfiguration Name="Release|x64" ExcludedFromBuild="true"/>
+			<FileConfiguration Name="Debug|x64" ExcludedFromBuild="true"/>
+			<FileConfiguration Name="Release|Win32" ExcludedFromBuild="true"/></File>
 		<File RelativePath="..\src\Solution\PETSc\PetscSolver.F90">
 			<FileConfiguration Name="Debug|Win32" ExcludedFromBuild="true"/>
 			<FileConfiguration Name="Release|x64" ExcludedFromBuild="true"/>
 			<FileConfiguration Name="Debug|x64" ExcludedFromBuild="true"/>
 			<FileConfiguration Name="Release|Win32" ExcludedFromBuild="true"/></File></Filter>
 		<File RelativePath="..\src\Solution\BaseSolution.f90"/>
+		<File RelativePath="..\src\Solution\ConvergenceSummary.f90"/>
 		<File RelativePath="..\src\Solution\ExplicitSolution.f90"/>
 		<File RelativePath="..\src\Solution\LinearSolverBase.f90"/>
 		<File RelativePath="..\src\Solution\LinearSolverFactory.F90">
@@ -260,21 +287,29 @@
 		<File RelativePath="..\src\Utilities\ArrayRead\LayeredArrayReader.f90"/></Filter>
 		<Filter Name="Idm">
 		<Filter Name="mf6blockfile">
+		<File RelativePath="..\src\Utilities\Idm\mf6blockfile\AsciiInputLoadType.f90"/>
 		<File RelativePath="..\src\Utilities\Idm\mf6blockfile\IdmMf6File.f90"/>
 		<File RelativePath="..\src\Utilities\Idm\mf6blockfile\LoadMf6File.f90"/>
+		<File RelativePath="..\src\Utilities\Idm\mf6blockfile\StressGridInput.f90"/>
+		<File RelativePath="..\src\Utilities\Idm\mf6blockfile\StressListInput.f90"/>
 		<File RelativePath="..\src\Utilities\Idm\mf6blockfile\StructArray.f90"/>
 		<File RelativePath="..\src\Utilities\Idm\mf6blockfile\StructVector.f90"/></Filter>
 		<Filter Name="selector">
 		<File RelativePath="..\src\Utilities\Idm\selector\IdmDfnSelector.f90"/>
+		<File RelativePath="..\src\Utilities\Idm\selector\IdmExgDfnSelector.f90"/>
 		<File RelativePath="..\src\Utilities\Idm\selector\IdmGwfDfnSelector.f90"/>
 		<File RelativePath="..\src\Utilities\Idm\selector\IdmGwtDfnSelector.f90"/>
 		<File RelativePath="..\src\Utilities\Idm\selector\IdmSimDfnSelector.f90"/></Filter>
+		<File RelativePath="..\src\Utilities\Idm\BoundInputContext.f90"/>
 		<File RelativePath="..\src\Utilities\Idm\DefinitionSelect.f90"/>
+		<File RelativePath="..\src\Utilities\Idm\IdmLoad.f90"/>
 		<File RelativePath="..\src\Utilities\Idm\IdmLogger.f90"/>
-		<File RelativePath="..\src\Utilities\Idm\IdmSimulation.f90"/>
 		<File RelativePath="..\src\Utilities\Idm\InputDefinition.f90"/>
+		<File RelativePath="..\src\Utilities\Idm\InputLoadType.f90"/>
 		<File RelativePath="..\src\Utilities\Idm\ModelPackageInputs.f90"/>
-		<File RelativePath="..\src\Utilities\Idm\ModflowInput.f90"/></Filter>
+		<File RelativePath="..\src\Utilities\Idm\ModflowInput.f90"/>
+		<File RelativePath="..\src\Utilities\Idm\SourceCommon.f90"/>
+		<File RelativePath="..\src\Utilities\Idm\SourceLoad.F90"/></Filter>
 		<Filter Name="Libraries">
 		<File RelativePath="..\src\Utilities\Libraries\blas\blas1_d.f90"/>
 		<File RelativePath="..\src\Utilities\Libraries\daglib\dag_module.f90"/>
@@ -353,7 +388,9 @@
 				<Tool Name="VFFortranCompilerTool" Preprocess="preprocessYes"/></FileConfiguration>
 			<FileConfiguration Name="Release|Win32">
 				<Tool Name="VFFortranCompilerTool" Preprocess="preprocessYes"/></FileConfiguration></File>
-		<File RelativePath="..\src\Utilities\genericutils.f90"/>
+		<File RelativePath="..\src\Utilities\DevFeature.f90"/>
+		<File RelativePath="..\src\Utilities\ErrorUtil.f90"/>
+		<File RelativePath="..\src\Utilities\GeomUtil.f90"/>
 		<File RelativePath="..\src\Utilities\HashTable.f90"/>
 		<File RelativePath="..\src\Utilities\HeadFileReader.f90"/>
 		<File RelativePath="..\src\Utilities\InputOutput.f90"/>
@@ -361,6 +398,8 @@
 		<File RelativePath="..\src\Utilities\kind.f90"/>
 		<File RelativePath="..\src\Utilities\List.f90"/>
 		<File RelativePath="..\src\Utilities\ListReader.f90"/>
+		<File RelativePath="..\src\Utilities\LongLineReader.f90"/>
+		<File RelativePath="..\src\Utilities\MathUtil.f90"/>
 		<File RelativePath="..\src\Utilities\Message.f90"/>
 		<File RelativePath="..\src\Utilities\OpenSpec.f90"/>
 		<File RelativePath="..\src\Utilities\PackageBudget.f90"/>
diff --git a/msvs/mf6lib.vfproj b/msvs/mf6lib.vfproj
index e89b383dde7..dee2f209199 100644
--- a/msvs/mf6lib.vfproj
+++ b/msvs/mf6lib.vfproj
@@ -143,13 +143,15 @@
 		<File RelativePath="..\src\Utilities\comarg.f90"/>
 		<File RelativePath="..\src\Utilities\compilerversion.fpp"/>
 		<File RelativePath="..\src\Utilities\Constants.f90"/>
-		<File RelativePath="..\src\Utilities\genericutils.f90"/>
+		<File RelativePath="..\src\Utilities\ErrorUtil.f90"/>
+		<File RelativePath="..\src\Utilities\GeomUtil.f90"/>
 		<File RelativePath="..\src\Utilities\HashTable.f90"/>
 		<File RelativePath="..\src\Utilities\InputOutput.f90"/>
 		<File RelativePath="..\src\Utilities\Iunit.f90"/>
 		<File RelativePath="..\src\Utilities\kind.f90"/>
 		<File RelativePath="..\src\Utilities\List.f90"/>
 		<File RelativePath="..\src\Utilities\ListReader.f90"/>
+		<File RelativePath="..\src\Utilities\LongLineReader.f90"/>
 		<File RelativePath="..\src\Utilities\OpenSpec.f90"/>
 		<File RelativePath="..\src\Utilities\Sim.f90"/>
 		<File RelativePath="..\src\Utilities\SimVariables.f90"/>
diff --git a/pymake/excludefiles.txt b/pymake/excludefiles.txt
index cc4f52a2306..33694f4ea5d 100644
--- a/pymake/excludefiles.txt
+++ b/pymake/excludefiles.txt
@@ -1,5 +1,6 @@
-../src/Solution/PETSc/PetscSolver.F90
 ../src/Solution/PETSc/PetscConvergence.F90
+../src/Solution/PETSc/PetscImsPreconditioner.F90
+../src/Solution/PETSc/PetscSolver.F90
 ../src/Solution/ParallelSolution.f90
 ../src/Utilities/Matrix/PetscMatrix.F90
 ../src/Utilities/Vector/PetscVector.F90
diff --git a/pymake/makefile b/pymake/makefile
index 484e7798cf0..8e7065a0d6d 100644
--- a/pymake/makefile
+++ b/pymake/makefile
@@ -114,7 +114,6 @@ $(OBJDIR)/GwfNpfOptions.o \
 $(OBJDIR)/GwfBuyInputData.o \
 $(OBJDIR)/ims8misc.o \
 $(OBJDIR)/LinearSolverBase.o \
-$(OBJDIR)/genericutils.o \
 $(OBJDIR)/ArrayHandlers.o \
 $(OBJDIR)/IndexMap.o \
 $(OBJDIR)/version.o \
diff --git a/src/Distributed/InterfaceMap.f90 b/src/Distributed/InterfaceMap.f90
index d373f014b3d..ef04bba288a 100644
--- a/src/Distributed/InterfaceMap.f90
+++ b/src/Distributed/InterfaceMap.f90
@@ -1,7 +1,7 @@
 module InterfaceMapModule
   use KindModule, only: I4B
   use ConstantsModule, only: LENMODELNAME, LENEXCHANGENAME
-  use ArrayHandlersModule, only: ExtendPtrArray, ifind
+  use ArrayHandlersModule, only: ifind
   use IndexMapModule
 
   implicit none
diff --git a/src/Distributed/Mapper.f90 b/src/Distributed/Mapper.f90
index d9713d82905..16e76985762 100644
--- a/src/Distributed/Mapper.f90
+++ b/src/Distributed/Mapper.f90
@@ -51,7 +51,7 @@ subroutine add_exchange_vars(this)
     integer(I4B) :: iconn
     class(SpatialModelConnectionType), pointer :: conn
     class(VirtualExchangeType), pointer :: virt_exg
-    character(len=LENMEMPATH) :: virt_mem_path
+    character(len=LENMEMPATH) :: virt_mem_path, local_mem_path
 
     do iconn = 1, baseconnectionlist%Count()
       conn => get_smc_from_list(baseconnectionlist, iconn)
@@ -60,11 +60,45 @@ subroutine add_exchange_vars(this)
         virt_mem_path = virt_exg%get_vrt_mem_path('NODEM1', '')
         call this%map_data_full(0, 'NODEM1', conn%prim_exchange%memoryPath, &
                                 'NODEM1', virt_mem_path, (/STG_BFR_CON_DF/))
+
+        ! these are only present when there is a mover:
+        if (virt_exg%has_mover()) then
+          local_mem_path = create_mem_path(virt_exg%name, 'MVR')
+          virt_mem_path = virt_exg%get_vrt_mem_path('QPACTUAL_M1', 'MVR')
+          call this%map_data_full(conn%owner%idsoln, 'QPACTUAL_M1', &
+                                  local_mem_path, 'QPACTUAL_M1', &
+                                  virt_mem_path, (/STG_BFR_EXG_FC/))
+          virt_mem_path = virt_exg%get_vrt_mem_path('QAVAILABLE_M1', 'MVR')
+          call this%map_data_full(conn%owner%idsoln, 'QAVAILABLE_M1', &
+                                  local_mem_path, 'QAVAILABLE_M1', &
+                                  virt_mem_path, (/STG_BFR_EXG_FC/))
+          virt_mem_path = virt_exg%get_vrt_mem_path('ID_MAPPED_M1', 'MVR')
+          call this%map_data_full(conn%owner%idsoln, 'ID_MAPPED_M1', &
+                                  local_mem_path, 'ID_MAPPED_M1', &
+                                  virt_mem_path, (/STG_AFT_CON_RP/))
+        end if
       end if
       if (.not. virt_exg%v_model2%is_local) then
         virt_mem_path = virt_exg%get_vrt_mem_path('NODEM2', '')
         call this%map_data_full(0, 'NODEM2', conn%prim_exchange%memoryPath, &
                                 'NODEM2', virt_mem_path, (/STG_BFR_CON_DF/))
+
+        ! these are only present when there is a mover:
+        if (virt_exg%has_mover()) then
+          local_mem_path = create_mem_path(virt_exg%name, 'MVR')
+          virt_mem_path = virt_exg%get_vrt_mem_path('QPACTUAL_M2', 'MVR')
+          call this%map_data_full(conn%owner%idsoln, 'QPACTUAL_M2', &
+                                  local_mem_path, 'QPACTUAL_M2', &
+                                  virt_mem_path, (/STG_BFR_EXG_FC/))
+          virt_mem_path = virt_exg%get_vrt_mem_path('QAVAILABLE_M2', 'MVR')
+          call this%map_data_full(conn%owner%idsoln, 'QAVAILABLE_M2', &
+                                  local_mem_path, 'QAVAILABLE_M2', &
+                                  virt_mem_path, (/STG_BFR_EXG_FC/))
+          virt_mem_path = virt_exg%get_vrt_mem_path('ID_MAPPED_M2', 'MVR')
+          call this%map_data_full(conn%owner%idsoln, 'ID_MAPPED_M2', &
+                                  local_mem_path, 'ID_MAPPED_M2', &
+                                  virt_mem_path, (/STG_AFT_CON_RP/))
+        end if
       end if
     end do
 
diff --git a/src/Distributed/MpiMessageBuilder.f90 b/src/Distributed/MpiMessageBuilder.f90
index 4c5c0f3c507..b92165923f8 100644
--- a/src/Distributed/MpiMessageBuilder.f90
+++ b/src/Distributed/MpiMessageBuilder.f90
@@ -713,18 +713,12 @@ subroutine get_mpi_datatype(this, virtual_data, el_displ, el_type, el_map_opt)
       call get_mpitype_for_int(mt, el_displ, el_type)
     else if (associated(mt%aint1d)) then
       call get_mpitype_for_int1d(mt, el_displ, el_type, el_map)
-    else if (associated(mt%aint2d)) then
-      call get_mpitype_for_int2d(mt, el_displ, el_type, el_map)
-    else if (associated(mt%aint3d)) then
-      call get_mpitype_for_int3d(mt, el_displ, el_type, el_map)
     else if (associated(mt%dblsclr)) then
       call get_mpitype_for_dbl(mt, el_displ, el_type)
     else if (associated(mt%adbl1d)) then
       call get_mpitype_for_dbl1d(mt, el_displ, el_type, el_map)
     else if (associated(mt%adbl2d)) then
       call get_mpitype_for_dbl2d(mt, el_displ, el_type, el_map)
-    else if (associated(mt%adbl3d)) then
-      call get_mpitype_for_dbl3d(mt, el_displ, el_type, el_map)
     else
       write (*, *) 'unsupported datatype in MPI messaging for ', &
         virtual_data%var_name, virtual_data%mem_path
@@ -793,50 +787,6 @@ subroutine get_mpitype_for_int1d(mem, el_displ, el_type, el_map)
 
   end subroutine get_mpitype_for_int1d
 
-  subroutine get_mpitype_for_int2d(mem, el_displ, el_type, el_map)
-    type(MemoryType), pointer :: mem
-    integer(kind=MPI_ADDRESS_KIND) :: el_displ
-    integer :: el_type
-    integer, dimension(:), pointer :: el_map
-    ! local
-    integer :: ierr
-    integer :: two_integer_type
-
-    call MPI_Get_address(mem%aint2d, el_displ, ierr)
-    if (associated(el_map)) then
-      call MPI_Type_contiguous(2, MPI_INTEGER, two_integer_type, ierr)
-      call MPI_Type_create_indexed_block( &
-        size(el_map), 1, el_map, two_integer_type, el_type, ierr)
-    else
-      call MPI_Type_contiguous(mem%isize, MPI_INTEGER, el_type, ierr)
-    end if
-    call MPI_Type_commit(el_type, ierr)
-    call MPI_Type_free(two_integer_type, ierr)
-
-  end subroutine get_mpitype_for_int2d
-
-  subroutine get_mpitype_for_int3d(mem, el_displ, el_type, el_map)
-    type(MemoryType), pointer :: mem
-    integer(kind=MPI_ADDRESS_KIND) :: el_displ
-    integer :: el_type
-    integer, dimension(:), pointer :: el_map
-    ! local
-    integer :: ierr
-    integer :: three_integer_type
-
-    call MPI_Get_address(mem%aint3d, el_displ, ierr)
-    if (associated(el_map)) then
-      call MPI_Type_contiguous(3, MPI_INTEGER, three_integer_type, ierr)
-      call MPI_Type_create_indexed_block( &
-        size(el_map), 1, el_map, three_integer_type, el_type, ierr)
-    else
-      call MPI_Type_contiguous(mem%isize, MPI_INTEGER, el_type, ierr)
-    end if
-    call MPI_Type_commit(el_type, ierr)
-    call MPI_Type_free(three_integer_type, ierr)
-
-  end subroutine get_mpitype_for_int3d
-
   subroutine get_mpitype_for_dbl(mem, el_displ, el_type)
     type(MemoryType), pointer :: mem
     integer(kind=MPI_ADDRESS_KIND) :: el_displ
@@ -876,41 +826,19 @@ subroutine get_mpitype_for_dbl2d(mem, el_displ, el_type, el_map)
     integer, dimension(:), pointer :: el_map
     ! local
     integer :: ierr
-    integer :: two_double_type
+    integer :: entry_type
 
     call MPI_Get_address(mem%adbl2d, el_displ, ierr)
     if (associated(el_map)) then
-      call MPI_Type_contiguous(2, MPI_DOUBLE_PRECISION, two_double_type, ierr)
+      call MPI_Type_contiguous( &
+        size(mem%adbl2d, dim=1), MPI_DOUBLE_PRECISION, entry_type, ierr)
       call MPI_Type_create_indexed_block( &
-        size(el_map), 1, el_map, two_double_type, el_type, ierr)
+        size(el_map), 1, el_map, entry_type, el_type, ierr)
     else
       call MPI_Type_contiguous(mem%isize, MPI_DOUBLE_PRECISION, el_type, ierr)
     end if
     call MPI_Type_commit(el_type, ierr)
-    call MPI_Type_free(two_double_type, ierr)
 
   end subroutine get_mpitype_for_dbl2d
 
-  subroutine get_mpitype_for_dbl3d(mem, el_displ, el_type, el_map)
-    type(MemoryType), pointer :: mem
-    integer(kind=MPI_ADDRESS_KIND) :: el_displ
-    integer :: el_type
-    integer, dimension(:), pointer :: el_map
-    ! local
-    integer :: ierr
-    integer :: three_double_type
-
-    call MPI_Get_address(mem%adbl3d, el_displ, ierr)
-    if (associated(el_map)) then
-      call MPI_Type_contiguous(3, MPI_DOUBLE_PRECISION, three_double_type, ierr)
-      call MPI_Type_create_indexed_block( &
-        size(el_map), 1, el_map, three_double_type, el_type, ierr)
-    else
-      call MPI_Type_contiguous(mem%isize, MPI_DOUBLE_PRECISION, el_type, ierr)
-    end if
-    call MPI_Type_commit(el_type, ierr)
-    call MPI_Type_free(three_double_type, ierr)
-
-  end subroutine get_mpitype_for_dbl3d
-
 end module MpiMessageBuilderModule
diff --git a/src/Distributed/MpiRouter.f90 b/src/Distributed/MpiRouter.f90
index cf0e544e016..e3cc403b832 100644
--- a/src/Distributed/MpiRouter.f90
+++ b/src/Distributed/MpiRouter.f90
@@ -129,7 +129,7 @@ subroutine mr_initialize(this)
       call this%message_builder%set_monitor(this%imon)
 
       ! write initial info
-      write (this%imon, '(a,/)') "initialize MPI Router:"
+      write (this%imon, '(a,/)') ">> initialize MPI Router:"
       write (this%imon, '(2x,a,i0)') "process id: ", proc_id
       write (this%imon, '(2x,a,i0)') "nr. of processes: ", nr_procs
       write (this%imon, '(2x,a,i0)') "nr. of models: ", nr_models
@@ -138,6 +138,7 @@ subroutine mr_initialize(this)
       do i = 1, nr_models
         write (this%imon, '(4x,2i8)') i, this%model_proc_ids(i)
       end do
+      write (this%imon, '(a,/)') "<< initialize done"
     end if
 
   end subroutine mr_initialize
@@ -175,8 +176,7 @@ subroutine mr_route_all(this, stage)
     integer(I4B) :: stage
 
     if (this%enable_monitor) then
-      write (this%imon, '(/,a)') "routing all"
-      write (this%imon, '(2a)') "routing stage: ", STG_TO_STR(stage)
+      write (this%imon, '(/,2a)') ">> routing all: ", STG_TO_STR(stage)
     end if
 
     ! route all
@@ -185,7 +185,7 @@ subroutine mr_route_all(this, stage)
     call this%deactivate()
 
     if (this%enable_monitor) then
-      write (this%imon, '(2a,/)') "end routing all: ", STG_TO_STR(stage)
+      write (this%imon, '(a,/)') "<< end routing all"
       !call mem_print_detailed(this%imon)
     end if
 
@@ -200,8 +200,8 @@ subroutine mr_route_sln(this, virtual_sol, stage)
     integer(I4B) :: stage
 
     if (this%enable_monitor) then
-      write (this%imon, '(/,a,i0)') "routing solution: ", virtual_sol%solution_id
-      write (this%imon, '(2a)') "routing stage: ", STG_TO_STR(stage)
+      write (this%imon, '(/,a,i0,2a)') ">> routing solution: ", &
+        virtual_sol%solution_id, ", ", STG_TO_STR(stage)
     end if
 
     ! route for this solution
@@ -210,7 +210,7 @@ subroutine mr_route_sln(this, virtual_sol, stage)
     call this%deactivate()
 
     if (this%enable_monitor) then
-      write (this%imon, '(2a)') "end routing solution: ", STG_TO_STR(stage)
+      write (this%imon, '(a)') "<< end routing solution"
     end if
 
   end subroutine mr_route_sln
diff --git a/src/Distributed/MpiRunControl.F90 b/src/Distributed/MpiRunControl.F90
index 32aa468a577..e37f50c174a 100644
--- a/src/Distributed/MpiRunControl.F90
+++ b/src/Distributed/MpiRunControl.F90
@@ -59,7 +59,6 @@ subroutine mpi_ctrl_start(this)
 
     inquire (file=petsc_db_file, exist=petsc_db_exists)
     if (.not. petsc_db_exists) then
-      write (*, *) 'WARNING. PETSc database file not found: '//petsc_db_file
       call PetscInitialize(PETSC_NULL_CHARACTER, ierr)
       CHKERRQ(ierr)
     else
diff --git a/src/Distributed/VirtualDataManager.f90 b/src/Distributed/VirtualDataManager.f90
index d1bb0688be4..a91b5e7eabe 100644
--- a/src/Distributed/VirtualDataManager.f90
+++ b/src/Distributed/VirtualDataManager.f90
@@ -3,14 +3,16 @@ module VirtualDataManagerModule
   use STLVecIntModule
   use VirtualDataListsModule, only: virtual_model_list, virtual_exchange_list
   use VirtualBaseModule, only: MAP_NODE_TYPE, MAP_CONN_TYPE
-  use VirtualModelModule, only: get_virtual_model
-  use VirtualExchangeModule, only: get_virtual_exchange
+  use VirtualModelModule, only: get_virtual_model, get_virtual_model_from_list
+  use VirtualExchangeModule, only: get_virtual_exchange, &
+                                   get_virtual_exchange_from_list
   use VirtualSolutionModule
   use VirtualDataContainerModule
   use RouterBaseModule
   use RouterFactoryModule, only: create_router
   use ListsModule, only: basesolutionlist
-  use NumericalSolutionModule, only: NumericalSolutionType
+  use NumericalSolutionModule, only: NumericalSolutionType, &
+                                     CastAsNumericalSolutionClass
   use NumericalModelModule, only: NumericalModelType, GetNumericalModelFromList
   use NumericalExchangeModule, only: NumericalExchangeType, &
                                      GetNumericalExchangeFromList
@@ -30,6 +32,7 @@ module VirtualDataManagerModule
     procedure :: create => vds_create
     procedure :: init => vds_init
     procedure :: add_solution => vds_add_solution
+    procedure :: set_halo => vds_set_halo
     procedure :: reduce_halo => vds_reduce_halo
     procedure :: synchronize => vds_synchronize
     procedure :: synchronize_sln => vds_synchronize_sln
@@ -90,6 +93,7 @@ subroutine vds_add_solution(this, num_sol)
     integer(I4B) :: model_id, exg_id
     type(STLVecInt) :: model_ids, exchange_ids
     class(VirtualDataContainerType), pointer :: vdc
+    logical :: found
 
     this%nr_solutions = this%nr_solutions + 1
     virt_sol => this%virtual_solutions(this%nr_solutions)
@@ -102,16 +106,34 @@ subroutine vds_add_solution(this, num_sol)
     virt_sol%solution_id = num_sol%id
     virt_sol%numerical_solution => num_sol
 
-    ! 1) adding all local models from the solution
+    ! 1) adding all local models with a virtual model counterpart from the solution
     do im = 1, num_sol%modellist%Count()
       num_mod => GetNumericalModelFromList(num_sol%modellist, im)
-      call model_ids%push_back(num_mod%id)
+      found = .false.
+      do i = 1, virtual_model_list%Count()
+        vdc => get_virtual_model_from_list(virtual_model_list, i)
+        if (num_mod%id == vdc%id) then
+          found = .true.
+          exit
+        end if
+      end do
+      if (found) then
+        call model_ids%push_back(num_mod%id)
+      end if
     end do
 
-    ! 2) adding all local exchanges
+    ! 2) adding all local exchanges with a virtual exchange counterpart
     do ix = 1, num_sol%exchangelist%Count()
       exg => GetDisConnExchangeFromList(num_sol%exchangelist, ix)
       if (.not. associated(exg)) cycle ! interface model is handled separately
+      found = .false.
+      do i = 1, virtual_exchange_list%Count()
+        vdc => get_virtual_exchange_from_list(virtual_exchange_list, i)
+        if (exg%id == vdc%id) then
+          found = .true.
+          exit
+        end if
+      end do
       call exchange_ids%push_back_unique(exg%id)
     end do
 
@@ -153,6 +175,69 @@ subroutine vds_add_solution(this, num_sol)
 
   end subroutine vds_add_solution
 
+  !> @brief Restrict the models and exchanges in the halo
+  !< to the set that has an actual chance of being used
+  subroutine vds_set_halo(this)
+    use ListsModule, only: basesolutionlist
+    use VirtualDataListsModule
+    use VirtualModelModule
+    use VirtualExchangeModule
+    class(VirtualDataManagerType) :: this
+    ! local
+    integer(I4B) :: i, imod, isol, iexg
+    type(STLVecInt) :: halo_model_ids
+    class(VirtualModelType), pointer :: vm
+    class(VirtualExchangeType), pointer :: ve
+    class(SpatialModelConnectionType), pointer :: conn
+    class(*), pointer :: sln_ptr
+
+    call halo_model_ids%init()
+
+    ! add halo models to list with ids (unique)
+    do isol = 1, basesolutionlist%Count()
+      sln_ptr => basesolutionlist%GetItem(isol)
+      select type (sln_ptr)
+      class is (NumericalSolutionType)
+        do iexg = 1, sln_ptr%exchangelist%Count()
+          conn => get_smc_from_list(sln_ptr%exchangelist, iexg)
+          if (.not. associated(conn)) cycle
+
+          ! add halo model ids to the list
+          do i = 1, conn%halo_models%size
+            call halo_model_ids%push_back_unique(conn%halo_models%at(i))
+          end do
+        end do
+      end select
+    end do
+
+    ! deactivate models that are not local, and not in halo
+    do imod = 1, virtual_model_list%Count()
+      vm => get_virtual_model_from_list(virtual_model_list, imod)
+      if (.not. vm%is_local) then
+        if (.not. halo_model_ids%contains(vm%id)) then
+          vm%is_active = .false.
+        end if
+      end if
+    end do
+
+    ! deactivate exchanges that are not local and outside halo
+    do iexg = 1, virtual_exchange_list%Count()
+      ve => get_virtual_exchange_from_list(virtual_exchange_list, iexg)
+      if (ve%v_model1%is_local .or. ve%v_model2%is_local) then
+        cycle
+      end if
+      if (halo_model_ids%contains(ve%v_model1%id) .and. &
+          halo_model_ids%contains(ve%v_model2%id)) then
+        cycle
+      end if
+
+      ve%is_active = .false.
+    end do
+
+    call halo_model_ids%destroy()
+
+  end subroutine vds_set_halo
+
   !> @brief Reduce the halo for all solutions. This will
   !< activate the mapping tables in the virtual data items.
   subroutine vds_reduce_halo(this)
@@ -173,7 +258,7 @@ subroutine vds_reduce_halo(this)
     ! merge the interface maps over this process
     do isol = 1, this%nr_solutions
       virt_sol => this%virtual_solutions(isol)
-      num_sol => virt_sol%numerical_solution
+      num_sol => CastAsNumericalSolutionClass(virt_sol%numerical_solution)
       do iexg = 1, num_sol%exchangelist%Count()
         conn => get_smc_from_list(num_sol%exchangelist, iexg)
         if (.not. associated(conn)) cycle
@@ -191,7 +276,8 @@ subroutine vds_reduce_halo(this)
       do isol = 1, this%nr_solutions
         write (outunit, '(a,i0,/)') "interface mape for solution ", &
           this%virtual_solutions(isol)%solution_id
-        call this%virtual_solutions(isol)%interface_map%print_interface(outunit)
+        virt_sol => this%virtual_solutions(isol)
+        call virt_sol%interface_map%print_interface(outunit)
       end do
       close (outunit)
     end if
@@ -230,13 +316,16 @@ subroutine prepare_all(this, stage)
     integer(I4B) :: i
     class(VirtualDataContainerType), pointer :: vdc
 
-    ! prepare all virtual data for this stage
+    ! prepare all virtual data for this stage,
+    ! cycle inactive to avoid redundant mem allocs
     do i = 1, virtual_model_list%Count()
       vdc => get_vdc_from_list(virtual_model_list, i)
+      if (.not. vdc%is_active) cycle
       call vdc%prepare_stage(stage)
     end do
     do i = 1, virtual_exchange_list%Count()
       vdc => get_vdc_from_list(virtual_exchange_list, i)
+      if (.not. vdc%is_active) cycle
       call vdc%prepare_stage(stage)
     end do
 
diff --git a/src/Distributed/VirtualExchange.f90 b/src/Distributed/VirtualExchange.f90
index f0554dab259..e849f990724 100644
--- a/src/Distributed/VirtualExchange.f90
+++ b/src/Distributed/VirtualExchange.f90
@@ -82,6 +82,7 @@ module VirtualExchangeModule
     procedure :: prepare_stage => vx_prepare_stage
     procedure :: get_send_items => vx_get_send_items
     procedure :: get_recv_items => vx_get_recv_items
+    procedure :: has_mover => vx_has_mover
     procedure :: destroy => vx_destroy
     ! private
     procedure, private :: init_virtual_data
@@ -241,6 +242,16 @@ subroutine vx_get_send_items(this, stage, rank, virtual_items)
 
   end subroutine vx_get_send_items
 
+  !> @brief Checks if there is an active mover in the exchange
+  !<
+  function vx_has_mover(this) result(has_mover)
+    class(VirtualExchangeType) :: this
+    logical(LGP) :: has_mover
+
+    has_mover = .false.
+
+  end function vx_has_mover
+
   subroutine vx_destroy(this)
     class(VirtualExchangeType) :: this
 
diff --git a/src/Distributed/VirtualGwfExchange.f90 b/src/Distributed/VirtualGwfExchange.f90
index 4c3670d0316..c49f3b79cd4 100644
--- a/src/Distributed/VirtualGwfExchange.f90
+++ b/src/Distributed/VirtualGwfExchange.f90
@@ -1,5 +1,8 @@
 module VirtualGwfExchangeModule
-  use KindModule, only: I4B
+  use KindModule, only: I4B, LGP
+  use STLVecIntModule
+  use SimStagesModule
+  use VirtualBaseModule
   use VirtualDataContainerModule, only: VDC_GWFEXG_TYPE
   use VirtualExchangeModule
   use VirtualDataListsModule, only: virtual_exchange_list
@@ -8,10 +11,30 @@ module VirtualGwfExchangeModule
 
   public :: add_virtual_gwf_exchange
 
+  !> For synchronization of GWF specific exchange data:
+  !< the exchange movers.
   type, public, extends(VirtualExchangeType) :: VirtualGwfExchangeType
+    type(VirtualIntType), pointer :: inmvr => null()
+    type(VirtualIntType), pointer :: mvr_maxmvr => null()
+    type(VirtualDbl1dType), pointer :: mvr_qpactual_m1 => null()
+    type(VirtualDbl1dType), pointer :: mvr_qpactual_m2 => null()
+    type(VirtualDbl1dType), pointer :: mvr_qavailable_m1 => null()
+    type(VirtualDbl1dType), pointer :: mvr_qavailable_m2 => null()
+    type(VirtualInt1dType), pointer :: mvr_id_mapped_m1 => null()
+    type(VirtualInt1dType), pointer :: mvr_id_mapped_m2 => null()
+    ! private
+    logical(LGP), private :: has_mvr !< backing field for function
   contains
     procedure :: create => vfx_create
+    procedure :: prepare_stage => vfx_prepare_stage
     procedure :: destroy => vfx_destroy
+    procedure :: get_send_items => vfx_get_send_items
+    procedure :: get_recv_items => vfx_get_recv_items
+    procedure :: has_mover => vfx_has_mover
+    ! private
+    procedure, private :: allocate_data
+    procedure, private :: deallocate_data
+    procedure, private :: init_virtual_data
   end type VirtualGwfExchangeType
 
 contains
@@ -47,12 +70,252 @@ subroutine vfx_create(this, name, exg_id, m1_id, m2_id)
     call this%VirtualExchangeType%create(name, exg_id, m1_id, m2_id)
     this%container_type = VDC_GWFEXG_TYPE
 
+    call this%allocate_data()
+    call this%init_virtual_data()
+
+    this%has_mvr = .false.
+
   end subroutine vfx_create
 
+  subroutine init_virtual_data(this)
+    class(VirtualGwfExchangeType) :: this
+    ! local
+    logical(LGP) :: is_nodem1_local
+    logical(LGP) :: is_nodem2_local
+
+    is_nodem1_local = this%v_model1%is_local
+    is_nodem2_local = this%v_model2%is_local
+    call this%set(this%inmvr%base(), 'INMVR', '', MAP_ALL_TYPE)
+    call this%set(this%mvr_maxmvr%base(), 'MAXMVR', 'MVR', MAP_ALL_TYPE)
+    ! these follow locality of nodem1,2
+    call this%set(this%mvr_qpactual_m1%base(), 'QPACTUAL_M1', 'MVR', &
+                  MAP_ALL_TYPE, is_nodem1_local)
+    call this%set(this%mvr_qpactual_m2%base(), 'QPACTUAL_M2', 'MVR', &
+                  MAP_ALL_TYPE, is_nodem2_local)
+    call this%set(this%mvr_qavailable_m1%base(), 'QAVAILABLE_M1', 'MVR', &
+                  MAP_ALL_TYPE, is_nodem1_local)
+    call this%set(this%mvr_qavailable_m2%base(), 'QAVAILABLE_M2', 'MVR', &
+                  MAP_ALL_TYPE, is_nodem2_local)
+    call this%set(this%mvr_id_mapped_m1%base(), 'ID_MAPPED_M1', 'MVR', &
+                  MAP_ALL_TYPE, is_nodem1_local)
+    call this%set(this%mvr_id_mapped_m2%base(), 'ID_MAPPED_M2', 'MVR', &
+                  MAP_ALL_TYPE, is_nodem2_local)
+
+  end subroutine init_virtual_data
+
+  subroutine vfx_prepare_stage(this, stage)
+    class(VirtualGwfExchangeType) :: this
+    integer(I4B) :: stage
+    ! local
+    integer(I4B) :: nmax
+
+    ! prepare base exchange data items
+    call this%VirtualExchangeType%prepare_stage(stage)
+
+    if (stage == STG_AFT_EXG_DF) then
+
+      call this%map(this%inmvr%base(), (/STG_AFT_EXG_DF/))
+
+    else if (stage == STG_AFT_CON_CR) then
+
+      ! at this point we know:
+      if (this%inmvr%get() > 0) then
+        this%has_mvr = .true.
+      end if
+
+    else if (stage == STG_BFR_CON_AR) then
+
+      ! only when MVR is active
+      if (this%inmvr%get() > 0) then
+        call this%map(this%mvr_maxmvr%base(), (/STG_BFR_CON_AR/))
+      end if
+
+    else if (stage == STG_AFT_CON_AR) then
+
+      ! only when MVR is active
+      if (this%inmvr%get() > 0) then
+        nmax = this%mvr_maxmvr%get()
+        if (nmax > 0) then
+          call this%map(this%mvr_qpactual_m1%base(), nmax, (/STG_BFR_EXG_FC/))
+          call this%map(this%mvr_qpactual_m2%base(), nmax, (/STG_BFR_EXG_FC/))
+          call this%map(this%mvr_qavailable_m1%base(), nmax, (/STG_BFR_EXG_FC/))
+          call this%map(this%mvr_qavailable_m2%base(), nmax, (/STG_BFR_EXG_FC/))
+          call this%map(this%mvr_id_mapped_m1%base(), nmax, (/STG_AFT_CON_RP/))
+          call this%map(this%mvr_id_mapped_m2%base(), nmax, (/STG_AFT_CON_RP/))
+        else
+          call this%map(this%mvr_qpactual_m1%base(), 0, (/STG_NEVER/))
+          call this%map(this%mvr_qpactual_m2%base(), 0, (/STG_NEVER/))
+          call this%map(this%mvr_qavailable_m1%base(), 0, (/STG_NEVER/))
+          call this%map(this%mvr_qavailable_m2%base(), 0, (/STG_NEVER/))
+          call this%map(this%mvr_id_mapped_m1%base(), 0, (/STG_NEVER/))
+          call this%map(this%mvr_id_mapped_m2%base(), 0, (/STG_NEVER/))
+        end if
+      end if
+
+    end if
+
+  end subroutine vfx_prepare_stage
+
+  subroutine vfx_get_recv_items(this, stage, rank, virtual_items)
+    class(VirtualGwfExchangeType) :: this
+    integer(I4B) :: stage
+    integer(I4B) :: rank
+    type(STLVecInt) :: virtual_items
+    ! local
+    integer(I4B) :: qpactual_m1_idx, qpactual_m2_idx
+    integer(I4B) :: qavailable_m1_idx, qavailable_m2_idx
+    integer(I4B) :: id_mapped_m1_idx, id_mapped_m2_idx
+    class(*), pointer :: vdi
+
+    ! get base items to receive
+    call this%VirtualExchangeType%get_recv_items(stage, rank, &
+                                                 virtual_items)
+
+    ! add more MVR items that follow nodem1/nodem2 pattern,
+    ! see comments in VirtualExchange for more details.
+    vdi => this%mvr_qpactual_m1
+    qpactual_m1_idx = this%virtual_data_list%GetIndex(vdi)
+    vdi => this%mvr_qpactual_m2
+    qpactual_m2_idx = this%virtual_data_list%GetIndex(vdi)
+    vdi => this%mvr_qavailable_m1
+    qavailable_m1_idx = this%virtual_data_list%GetIndex(vdi)
+    vdi => this%mvr_qavailable_m2
+    qavailable_m2_idx = this%virtual_data_list%GetIndex(vdi)
+    vdi => this%mvr_id_mapped_m1
+    id_mapped_m1_idx = this%virtual_data_list%GetIndex(vdi)
+    vdi => this%mvr_id_mapped_m2
+    id_mapped_m2_idx = this%virtual_data_list%GetIndex(vdi)
+
+    if (this%v_model1%is_local .and. &
+        this%v_model2%orig_rank == rank) then
+      ! this is our dual exchange on the other rank,
+      ! only receive qpactual_m2
+      if (this%mvr_qpactual_m2%check_stage(stage)) then
+        call virtual_items%push_back(qpactual_m2_idx)
+      end if
+      if (this%mvr_qavailable_m2%check_stage(stage)) then
+        call virtual_items%push_back(qavailable_m2_idx)
+      end if
+      if (this%mvr_id_mapped_m2%check_stage(stage)) then
+        call virtual_items%push_back(id_mapped_m2_idx)
+      end if
+    else if (this%v_model2%is_local .and. &
+             this%v_model1%orig_rank == rank) then
+      ! the reverse case...
+      if (this%mvr_qpactual_m1%check_stage(stage)) then
+        call virtual_items%push_back(qpactual_m1_idx)
+      end if
+      if (this%mvr_qavailable_m1%check_stage(stage)) then
+        call virtual_items%push_back(qavailable_m1_idx)
+      end if
+      if (this%mvr_id_mapped_m1%check_stage(stage)) then
+        call virtual_items%push_back(id_mapped_m1_idx)
+      end if
+    end if
+
+  end subroutine vfx_get_recv_items
+
+  subroutine vfx_get_send_items(this, stage, rank, virtual_items)
+    class(VirtualGwfExchangeType) :: this
+    integer(I4B) :: stage
+    integer(I4B) :: rank
+    type(STLVecInt) :: virtual_items
+    ! local
+    integer(I4B) :: qpactual_m1_idx, qpactual_m2_idx
+    integer(I4B) :: qavailable_m1_idx, qavailable_m2_idx
+    integer(I4B) :: id_mapped_m1_idx, id_mapped_m2_idx
+    class(*), pointer :: vdi
+
+    ! get base items to send
+    call this%VirtualExchangeType%get_send_items(stage, rank, &
+                                                 virtual_items)
+
+    ! add more MVR items that follow nodem1/nodem2 pattern
+    vdi => this%mvr_qpactual_m1
+    qpactual_m1_idx = this%virtual_data_list%GetIndex(vdi)
+    vdi => this%mvr_qpactual_m2
+    qpactual_m2_idx = this%virtual_data_list%GetIndex(vdi)
+    vdi => this%mvr_qavailable_m1
+    qavailable_m1_idx = this%virtual_data_list%GetIndex(vdi)
+    vdi => this%mvr_qavailable_m2
+    qavailable_m2_idx = this%virtual_data_list%GetIndex(vdi)
+    vdi => this%mvr_id_mapped_m1
+    id_mapped_m1_idx = this%virtual_data_list%GetIndex(vdi)
+    vdi => this%mvr_id_mapped_m2
+    id_mapped_m2_idx = this%virtual_data_list%GetIndex(vdi)
+
+    if (this%v_model1%is_local .and. &
+        this%v_model2%orig_rank == rank) then
+      ! this is our dual exchange on the other rank,
+      ! only add qpactual_m1
+      if (this%mvr_qpactual_m1%check_stage(stage)) then
+        call virtual_items%push_back(qpactual_m1_idx)
+      end if
+      if (this%mvr_qavailable_m1%check_stage(stage)) then
+        call virtual_items%push_back(qavailable_m1_idx)
+      end if
+      if (this%mvr_id_mapped_m1%check_stage(stage)) then
+        call virtual_items%push_back(id_mapped_m1_idx)
+      end if
+    else if (this%v_model2%is_local .and. &
+             this%v_model1%orig_rank == rank) then
+      ! the reverse case...
+      if (this%mvr_qpactual_m2%check_stage(stage)) then
+        call virtual_items%push_back(qpactual_m2_idx)
+      end if
+      if (this%mvr_qavailable_m2%check_stage(stage)) then
+        call virtual_items%push_back(qavailable_m2_idx)
+      end if
+      if (this%mvr_id_mapped_m2%check_stage(stage)) then
+        call virtual_items%push_back(id_mapped_m2_idx)
+      end if
+    end if
+
+  end subroutine vfx_get_send_items
+
+  !> @brief Override
+  !<
+  function vfx_has_mover(this) result(has_mover)
+    class(VirtualGwfExchangeType) :: this
+    logical(LGP) :: has_mover
+
+    has_mover = this%has_mvr
+
+  end function vfx_has_mover
+
+  subroutine allocate_data(this)
+    class(VirtualGwfExchangeType) :: this
+
+    allocate (this%inmvr)
+    allocate (this%mvr_maxmvr)
+    allocate (this%mvr_qpactual_m1)
+    allocate (this%mvr_qpactual_m2)
+    allocate (this%mvr_qavailable_m1)
+    allocate (this%mvr_qavailable_m2)
+    allocate (this%mvr_id_mapped_m1)
+    allocate (this%mvr_id_mapped_m2)
+
+  end subroutine allocate_data
+
+  subroutine deallocate_data(this)
+    class(VirtualGwfExchangeType) :: this
+
+    deallocate (this%inmvr)
+    deallocate (this%mvr_maxmvr)
+    deallocate (this%mvr_qpactual_m1)
+    deallocate (this%mvr_qpactual_m2)
+    deallocate (this%mvr_qavailable_m1)
+    deallocate (this%mvr_qavailable_m2)
+    deallocate (this%mvr_id_mapped_m1)
+    deallocate (this%mvr_id_mapped_m2)
+
+  end subroutine deallocate_data
+
   subroutine vfx_destroy(this)
     class(VirtualGwfExchangeType) :: this
 
     call this%VirtualExchangeType%destroy()
+    call this%deallocate_data()
 
   end subroutine vfx_destroy
 
diff --git a/src/Distributed/VirtualGwfModel.f90 b/src/Distributed/VirtualGwfModel.f90
index 86a973e5a13..0f6d2390ade 100644
--- a/src/Distributed/VirtualGwfModel.f90
+++ b/src/Distributed/VirtualGwfModel.f90
@@ -16,6 +16,7 @@ module VirtualGwfModelModule
     type(VirtualIntType), pointer :: npf_iangle2 => null()
     type(VirtualIntType), pointer :: npf_iangle3 => null()
     type(VirtualIntType), pointer :: npf_iwetdry => null()
+    type(VirtualIntType), pointer :: inbuy => null()
     type(VirtualInt1dType), pointer :: npf_icelltype => null()
     type(VirtualDbl1dType), pointer :: npf_k11 => null()
     type(VirtualDbl1dType), pointer :: npf_k22 => null()
@@ -24,6 +25,7 @@ module VirtualGwfModelModule
     type(VirtualDbl1dType), pointer :: npf_angle2 => null()
     type(VirtualDbl1dType), pointer :: npf_angle3 => null()
     type(VirtualDbl1dType), pointer :: npf_wetdry => null()
+    type(VirtualDbl1dType), pointer :: buy_dense => null()
   contains
     ! public
     procedure :: create => vgwf_create
@@ -78,6 +80,7 @@ subroutine init_virtual_data(this)
     call this%set(this%npf_iangle2%base(), 'IANGLE2', 'NPF', MAP_ALL_TYPE)
     call this%set(this%npf_iangle3%base(), 'IANGLE3', 'NPF', MAP_ALL_TYPE)
     call this%set(this%npf_iwetdry%base(), 'IWETDRY', 'NPF', MAP_ALL_TYPE)
+    call this%set(this%inbuy%base(), 'INBUY', '', MAP_ALL_TYPE)
     call this%set(this%npf_icelltype%base(), 'ICELLTYPE', 'NPF', MAP_NODE_TYPE)
     call this%set(this%npf_k11%base(), 'K11', 'NPF', MAP_NODE_TYPE)
     call this%set(this%npf_k22%base(), 'K22', 'NPF', MAP_NODE_TYPE)
@@ -86,6 +89,7 @@ subroutine init_virtual_data(this)
     call this%set(this%npf_angle2%base(), 'ANGLE2', 'NPF', MAP_NODE_TYPE)
     call this%set(this%npf_angle3%base(), 'ANGLE3', 'NPF', MAP_NODE_TYPE)
     call this%set(this%npf_wetdry%base(), 'WETDRY', 'NPF', MAP_NODE_TYPE)
+    call this%set(this%buy_dense%base(), 'DENSE', 'BUY', MAP_NODE_TYPE)
 
   end subroutine init_virtual_data
 
@@ -104,6 +108,7 @@ subroutine vgwf_prepare_stage(this, stage)
       call this%map(this%npf_iangle2%base(), (/STG_AFT_MDL_DF/))
       call this%map(this%npf_iangle3%base(), (/STG_AFT_MDL_DF/))
       call this%map(this%npf_iwetdry%base(), (/STG_AFT_MDL_DF/))
+      call this%map(this%inbuy%base(), (/STG_AFT_MDL_DF/))
 
     else if (stage == STG_BFR_CON_AR) then
 
@@ -142,6 +147,12 @@ subroutine vgwf_prepare_stage(this, stage)
         call this%map(this%npf_wetdry%base(), 0, (/STG_NEVER/))
       end if
 
+      if (this%inbuy%get() > 0) then
+        call this%map(this%buy_dense%base(), nr_nodes, (/STG_BFR_EXG_CF/))
+      else
+        call this%map(this%buy_dense%base(), 0, (/STG_NEVER/))
+      end if
+
     end if
 
   end subroutine vgwf_prepare_stage
@@ -161,6 +172,7 @@ subroutine allocate_data(this)
     allocate (this%npf_iangle2)
     allocate (this%npf_iangle3)
     allocate (this%npf_iwetdry)
+    allocate (this%inbuy)
     allocate (this%npf_icelltype)
     allocate (this%npf_k11)
     allocate (this%npf_k22)
@@ -169,6 +181,7 @@ subroutine allocate_data(this)
     allocate (this%npf_angle2)
     allocate (this%npf_angle3)
     allocate (this%npf_wetdry)
+    allocate (this%buy_dense)
 
   end subroutine allocate_data
 
@@ -179,6 +192,7 @@ subroutine deallocate_data(this)
     deallocate (this%npf_iangle2)
     deallocate (this%npf_iangle3)
     deallocate (this%npf_iwetdry)
+    deallocate (this%inbuy)
     deallocate (this%npf_icelltype)
     deallocate (this%npf_k11)
     deallocate (this%npf_k22)
@@ -187,6 +201,7 @@ subroutine deallocate_data(this)
     deallocate (this%npf_angle2)
     deallocate (this%npf_angle3)
     deallocate (this%npf_wetdry)
+    deallocate (this%buy_dense)
 
   end subroutine deallocate_data
 
diff --git a/src/Distributed/VirtualGwtModel.f90 b/src/Distributed/VirtualGwtModel.f90
index 4d0b526da89..75e796886bc 100644
--- a/src/Distributed/VirtualGwtModel.f90
+++ b/src/Distributed/VirtualGwtModel.f90
@@ -89,7 +89,7 @@ subroutine init_virtual_data(this)
     call this%set(this%fmi_gwfhead%base(), 'GWFHEAD', 'FMI', MAP_NODE_TYPE)
     call this%set(this%fmi_gwfsat%base(), 'GWFSAT', 'FMI', MAP_NODE_TYPE)
     call this%set(this%fmi_gwfspdis%base(), 'GWFSPDIS', 'FMI', MAP_NODE_TYPE)
-    call this%set(this%fmi_gwfflowja%base(), 'GWFFLOWJA', 'FMI', MAP_NODE_TYPE)
+    call this%set(this%fmi_gwfflowja%base(), 'GWFFLOWJA', 'FMI', MAP_CONN_TYPE)
     call this%set(this%mst_thetam%base(), 'THETAM', 'MST', MAP_NODE_TYPE)
     call this%set(this%indsp%base(), 'INDSP', '', MAP_ALL_TYPE)
     call this%set(this%inmst%base(), 'INMST', '', MAP_ALL_TYPE)
@@ -117,6 +117,9 @@ subroutine vgwt_prepare_stage(this, stage)
 
     else if (stage == STG_BFR_CON_AR) then
 
+      nr_nodes = this%element_maps(MAP_NODE_TYPE)%nr_virt_elems
+      nr_conns = this%element_maps(MAP_CONN_TYPE)%nr_virt_elems
+
       call this%map(this%x%base(), nr_nodes, &
                     (/STG_BFR_CON_AR, STG_BFR_EXG_AD, STG_BFR_EXG_CF/))
       call this%map(this%ibound%base(), nr_nodes, (/STG_BFR_CON_AR/))
diff --git a/src/Distributed/VirtualModel.f90 b/src/Distributed/VirtualModel.f90
index 4a5f761e865..8eca0628f6c 100644
--- a/src/Distributed/VirtualModel.f90
+++ b/src/Distributed/VirtualModel.f90
@@ -13,9 +13,15 @@ module VirtualModelModule
   public :: get_virtual_model_from_list
   public :: get_virtual_model
 
+  interface get_virtual_model
+    module procedure get_virtual_model_by_id, &
+      get_virtual_model_by_name
+  end interface
+
   type, public, extends(VirtualDataContainerType) :: VirtualModelType
     class(NumericalModelType), pointer :: local_model
     ! CON
+    type(VirtualIntType), pointer :: con_ianglex => null()
     type(VirtualInt1dType), pointer :: con_ia => null()
     type(VirtualInt1dType), pointer :: con_ja => null()
     type(VirtualInt1dType), pointer :: con_jas => null()
@@ -44,6 +50,8 @@ module VirtualModelModule
     type(VirtualDbl1dType), pointer :: x => null()
     type(VirtualDbl1dType), pointer :: x_old => null()
     type(VirtualInt1dType), pointer :: ibound => null()
+    ! Base Model fields
+    type(VirtualIntType), pointer :: idsoln => null()
   contains
     ! public
     procedure :: create => vm_create
@@ -86,6 +94,7 @@ subroutine init_virtual_data(this)
     class(VirtualModelType) :: this
 
     ! CON
+    call this%set(this%con_ianglex%base(), 'IANGLEX', 'CON', MAP_ALL_TYPE)
     call this%set(this%con_ia%base(), 'IA', 'CON', MAP_ALL_TYPE)
     call this%set(this%con_ja%base(), 'JA', 'CON', MAP_ALL_TYPE)
     call this%set(this%con_jas%base(), 'JAS', 'CON', MAP_ALL_TYPE)
@@ -114,6 +123,8 @@ subroutine init_virtual_data(this)
     call this%set(this%x%base(), 'X', '', MAP_NODE_TYPE)
     call this%set(this%x_old%base(), 'XOLD', '', MAP_NODE_TYPE)
     call this%set(this%ibound%base(), 'IBOUND', '', MAP_NODE_TYPE)
+    ! Base model
+    call this%set(this%idsoln%base(), 'IDSOLN', '', MAP_ALL_TYPE)
 
   end subroutine init_virtual_data
 
@@ -126,6 +137,8 @@ subroutine vm_prepare_stage(this, stage)
 
     if (stage == STG_AFT_MDL_DF) then
 
+      call this%map(this%idsoln%base(), (/STG_AFT_MDL_DF/))
+      call this%map(this%con_ianglex%base(), (/STG_AFT_MDL_DF/))
       call this%map(this%dis_ndim%base(), (/STG_AFT_MDL_DF/))
       call this%map(this%dis_nodes%base(), (/STG_AFT_MDL_DF/))
       call this%map(this%dis_nodesuser%base(), (/STG_AFT_MDL_DF/))
@@ -167,7 +180,11 @@ subroutine vm_prepare_stage(this, stage)
       call this%map(this%con_hwva%base(), njas, (/STG_BFR_CON_DF/))
       call this%map(this%con_cl1%base(), njas, (/STG_BFR_CON_DF/))
       call this%map(this%con_cl2%base(), njas, (/STG_BFR_CON_DF/))
-      call this%map(this%con_anglex%base(), njas, (/STG_BFR_CON_DF/))
+      if (this%con_ianglex%get() > 0) then
+        call this%map(this%con_anglex%base(), njas, (/STG_BFR_CON_DF/))
+      else
+        call this%map(this%con_anglex%base(), 0, (/STG_NEVER/))
+      end if
 
     end if
 
@@ -216,6 +233,7 @@ end subroutine vm_destroy
   subroutine allocate_data(this)
     class(VirtualModelType) :: this
 
+    allocate (this%con_ianglex)
     allocate (this%con_ia)
     allocate (this%con_ja)
     allocate (this%con_jas)
@@ -242,6 +260,7 @@ subroutine allocate_data(this)
     allocate (this%x)
     allocate (this%x_old)
     allocate (this%ibound)
+    allocate (this%idsoln)
 
   end subroutine allocate_data
 
@@ -249,6 +268,7 @@ subroutine deallocate_data(this)
     class(VirtualModelType) :: this
 
     ! CON
+    deallocate (this%con_ianglex)
     deallocate (this%con_ia)
     deallocate (this%con_ja)
     deallocate (this%con_jas)
@@ -276,6 +296,8 @@ subroutine deallocate_data(this)
     deallocate (this%x)
     deallocate (this%x_old)
     deallocate (this%ibound)
+    ! Base model
+    deallocate (this%idsoln)
 
   end subroutine deallocate_data
 
@@ -322,9 +344,9 @@ function eq_numerical_model(this, num_model) result(is_equal)
 
   end function eq_numerical_model
 
-!> @brief Returns a virtual model with the specified id
-!< from the global list
-  function get_virtual_model(model_id) result(virtual_model)
+  !> @brief Returns a virtual model with the specified id
+  !< from the global list, or null
+  function get_virtual_model_by_id(model_id) result(virtual_model)
     use VirtualDataListsModule, only: virtual_model_list
     integer(I4B) :: model_id
     class(VirtualModelType), pointer :: virtual_model
@@ -344,6 +366,30 @@ function get_virtual_model(model_id) result(virtual_model)
       end select
     end do
 
-  end function get_virtual_model
+  end function get_virtual_model_by_id
+
+  !> @brief Returns a virtual model with the specified name
+  !< from the global list, or null
+  function get_virtual_model_by_name(model_name) result(virtual_model)
+    use VirtualDataListsModule, only: virtual_model_list
+    character(len=*) :: model_name
+    class(VirtualModelType), pointer :: virtual_model
+    ! local
+    integer(I4B) :: i
+    class(*), pointer :: vm
+
+    virtual_model => null()
+    do i = 1, virtual_model_list%Count()
+      vm => virtual_model_list%GetItem(i)
+      select type (vm)
+      class is (VirtualModelType)
+        if (vm%name == model_name) then
+          virtual_model => vm
+          return
+        end if
+      end select
+    end do
+
+  end function get_virtual_model_by_name
 
 end module VirtualModelModule
diff --git a/src/Distributed/VirtualSolution.f90 b/src/Distributed/VirtualSolution.f90
index 94a7c94ca5b..0433ba6a8b2 100644
--- a/src/Distributed/VirtualSolution.f90
+++ b/src/Distributed/VirtualSolution.f90
@@ -2,7 +2,6 @@ module VirtualSolutionModule
   use KindModule, only: I4B
   use ListModule
   use VirtualDataContainerModule, only: VdcPtrType
-  use NumericalSolutionModule ! TODO_MJR: this should not be here!!
   use InterfaceMapModule
   implicit none
   private
@@ -13,7 +12,7 @@ module VirtualSolutionModule
     integer(I4B) :: solution_id = -1
     type(VdcPtrType), dimension(:), pointer :: models => null() !< the models as virtual data containers (wrapped)
     type(VdcPtrType), dimension(:), pointer :: exchanges => null() !< the exchanges as virtual data containers (wrapped)
-    class(NumericalSolutionType), pointer :: numerical_solution => null() !< points back to the actual numerical solution
+    class(*), pointer :: numerical_solution => null() !< points back to the actual numerical solution
     type(InterfaceMapType), pointer :: interface_map => null() !< contains the aggregate interface map for the solution
                                                                !! NB: the aggregation is over multiple interface models
                                                                !! and there is no unique numbering there. The target
diff --git a/src/Exchange/BaseExchange.f90 b/src/Exchange/BaseExchange.f90
index 5b323c6ea52..afc1406f79a 100644
--- a/src/Exchange/BaseExchange.f90
+++ b/src/Exchange/BaseExchange.f90
@@ -14,8 +14,11 @@ module BaseExchangeModule
   type, abstract :: BaseExchangeType
     character(len=LENEXCHANGENAME) :: name !< the name of this exchange
     character(len=LENMEMPATH) :: memoryPath !< the location in the memory manager where the variables are stored
+    character(len=LENMEMPATH) :: input_mempath
     integer(I4B) :: id
+
   contains
+
     procedure(exg_df), deferred :: exg_df
     procedure(exg_ar), deferred :: exg_ar
     procedure :: exg_rp
@@ -42,18 +45,13 @@ subroutine exg_ar(this)
 
 contains
 
+  !> @brief Read and prepare
+  !<
   subroutine exg_rp(this)
-! ******************************************************************************
-! exg_rp -- Read and prepare
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: readnewdata
     ! -- dummy
     class(BaseExchangeType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Check with TDIS on whether or not it is time to RP
     if (.not. readnewdata) return
@@ -64,17 +62,11 @@ subroutine exg_rp(this)
     return
   end subroutine exg_rp
 
+  !> @brief Calculate time step length
+  !<
   subroutine exg_calculate_delt(this)
-! ******************************************************************************
-! exg_calculate_delt -- Calculate time step length
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BaseExchangeType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Nothing to do for TU
     !
@@ -82,78 +74,59 @@ subroutine exg_calculate_delt(this)
     return
   end subroutine exg_calculate_delt
 
+  !> @brief Run output routines
+  !<
   subroutine exg_ot(this)
-! ******************************************************************************
-! exg_ot -- Output
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BaseExchangeType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Return
     return
   end subroutine exg_ot
 
+  !> @brief Final processing
+  !<
   subroutine exg_fp(this)
-! ******************************************************************************
-! exg_fp -- Final processing
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BaseExchangeType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Return
     return
   end subroutine exg_fp
 
+  !> @brief Deallocate memory
+  !<
   subroutine exg_da(this)
-! ******************************************************************************
-! exg_da -- Deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BaseExchangeType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Return
     return
   end subroutine exg_da
 
-  !> @brief should return true when the exchange should be
-  !! added to the solution where the model resides
+  !> @brief Should return true when the exchange should be added to the
+  !! solution where the model resides
   !<
   function connects_model(this, model) result(is_connected)
+    ! -- dummy
     class(BaseExchangeType) :: this !< the instance of the exchange
     class(BaseModelType), pointer, intent(in) :: model !< the model to which the exchange might hold a connection
+    ! -- return
     logical(LGP) :: is_connected !< true, when connected
-
+    !
     is_connected = .false.
-
+    !
+    ! -- Return
+    return
   end function
 
+  !> @brief Cast the object passed in as BaseExchangeType and return it
+  !<
   function CastAsBaseExchangeClass(obj) result(res)
-! ******************************************************************************
-! CastAsBaseExchangeClass
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(*), pointer, intent(inout) :: obj
     ! -- return
     class(BaseExchangeType), pointer :: res
-! ------------------------------------------------------------------------------
     !
     res => null()
     if (.not. associated(obj)) return
@@ -162,47 +135,41 @@ function CastAsBaseExchangeClass(obj) result(res)
     class is (BaseExchangeType)
       res => obj
     end select
+    !
+    ! -- Return
     return
   end function CastAsBaseExchangeClass
 
+  !> @brief Add the exchange object (BaseExchangeType) to a list
+  !<
   subroutine AddBaseExchangeToList(list, exchange)
-! ******************************************************************************
-! AddBaseExchangeToList
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(ListType), intent(inout) :: list
     class(BaseExchangeType), pointer, intent(inout) :: exchange
     ! -- local
     class(*), pointer :: obj
-! ------------------------------------------------------------------------------
     !
     obj => exchange
     call list%Add(obj)
     !
+    ! -- Return
     return
   end subroutine AddBaseExchangeToList
 
+  !> @brief Retrieve a specific BaseExchangeType object from a list
+  !<
   function GetBaseExchangeFromList(list, idx) result(res)
-! ******************************************************************************
-! GetBaseExchangeFromList
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(ListType), intent(inout) :: list
     integer(I4B), intent(in) :: idx
     class(BaseExchangeType), pointer :: res
     ! -- local
     class(*), pointer :: obj
-! ------------------------------------------------------------------------------
     !
     obj => list%GetItem(idx)
     res => CastAsBaseExchangeClass(obj)
     !
+    ! -- Return
     return
   end function GetBaseExchangeFromList
 
diff --git a/src/Exchange/DisConnExchange.f90 b/src/Exchange/DisConnExchange.f90
index b8f5118009d..b41402dc366 100644
--- a/src/Exchange/DisConnExchange.f90
+++ b/src/Exchange/DisConnExchange.f90
@@ -2,10 +2,10 @@ module DisConnExchangeModule
   use KindModule, only: I4B, DP, LGP
   use SimVariablesModule, only: errmsg
   use ConstantsModule, only: LENAUXNAME, LENBOUNDNAME, LINELENGTH
+  use SimModule, only: store_error, count_errors, store_error_filename
   use CharacterStringModule
   use ListModule, only: ListType
   use MemoryManagerModule, only: mem_allocate, mem_reallocate
-  use BlockParserModule, only: BlockParserType
   use NumericalModelModule, only: NumericalModelType
   use VirtualModelModule, only: VirtualModelType
   use NumericalExchangeModule, only: NumericalExchangeType
@@ -28,7 +28,7 @@ module DisConnExchangeModule
     class(VirtualModelType), pointer :: v_model1 => null() !< virtual model 1
     class(VirtualModelType), pointer :: v_model2 => null() !< virtual model 2
     logical(LGP) :: is_datacopy !< when true, this exchange is just a data copy on another process and
-                                !! not responsible for controlling movers, observations, ...
+                                !! not responsible for controlling movers, observations, ... TODO_MJR: refactor this with the new mover!!!
 
     integer(I4B), pointer :: nexg => null() !< number of exchanges
     integer(I4B), dimension(:), pointer, contiguous :: nodem1 => null() !< node numbers in model 1
@@ -49,12 +49,12 @@ module DisConnExchangeModule
     integer(I4B), pointer :: ianglex => null() !< flag indicating anglex was read, if read, ianglex is index in auxvar
     integer(I4B), pointer :: icdist => null() !< flag indicating cdist was read, if read, icdist is index in auxvar
     integer(I4B), pointer :: iprpak => null() !< print input flag
+    integer(I4B), pointer :: iprflow => null() !< print flag for cell by cell flows
+    integer(I4B), pointer :: ipakcb => null() !< save flag for cell by cell flows
     integer(I4B), pointer :: inamedbound => null() !< flag to read boundnames
 
     integer(I4B), pointer :: ixt3d => null() !< flag indicating if XT3D should be applied on the interface: 0 = off, 1 = lhs, 2 = rhs
-    logical(LGP) :: dev_ifmod_on !< development option, forces interface model for this exchange
-
-    type(BlockParserType) :: parser !< block parser for input file (controlled from derived type)
+    logical(LGP), pointer :: dev_ifmod_on !< development option, forces interface model for this exchange
 
   contains
 
@@ -64,50 +64,67 @@ module DisConnExchangeModule
     procedure :: use_interface_model
 
     ! protected
-    procedure, pass(this) :: parse_option
-    procedure, pass(this) :: read_dimensions
-    procedure, pass(this) :: read_data
+    procedure, pass(this) :: source_options
+    procedure, pass(this) :: source_dimensions
+    procedure, pass(this) :: source_data
+    procedure, pass(this) :: noder
+    procedure, pass(this) :: cellstr
 
   end type DisConnExchangeType
 
+  !> @ brief DisConnExchangeFoundType
+  !!
+  !!  This type is used to simplify the tracking of common parameters
+  !!  that are sourced from the input context.
+  !<
+  type DisConnExchangeFoundType
+    logical :: naux = .false.
+    logical :: ipakcb = .false.
+    logical :: iprpak = .false.
+    logical :: iprflow = .false.
+    logical :: boundnames = .false.
+    logical :: auxiliary = .false.
+    logical :: dev_ifmod_on = .false.
+    logical :: nexg = .false.
+  end type DisConnExchangeFoundType
+
 contains
 
-  !> @brief Parse option from exchange file
+  !> @brief Source options from input context
   !<
-  function parse_option(this, keyword, iout) result(parsed)
+  subroutine source_options(this, iout)
+    ! -- modules
+    use MemoryManagerExtModule, only: mem_set_value
     use ArrayHandlersModule, only: ifind
-    use InputOutputModule, only: urdaux
+    ! -- dummy
     class(DisConnExchangeType) :: this !< instance of exchange object
-    character(len=LINELENGTH), intent(in) :: keyword !< the option name
     integer(I4B), intent(in) :: iout !< for logging
-    logical(LGP) :: parsed !< true when parsed
-    ! local
-    integer(I4B) :: istart
-    integer(I4B) :: istop
-    integer(I4B) :: lloc
-    integer(I4B) :: n
-    integer(I4B) :: ival
-
-    character(len=:), allocatable :: line
-    character(len=LENAUXNAME), dimension(:), allocatable :: caux
-
-    parsed = .true.
-
-    select case (keyword)
-    case ('AUXILIARY')
-      call this%parser%GetRemainingLine(line)
-      lloc = 1
-      call urdaux(this%naux, this%parser%iuactive, iout, lloc, istart, &
-                  istop, caux, line, 'GWF_GWF_Exchange')
+    ! -- local
+    type(DisConnExchangeFoundType) :: found
+    integer(I4B) :: ival, n
+    !
+    ! -- update defaults with idm sourced values
+    call mem_set_value(this%naux, 'NAUX', this%input_mempath, found%naux)
+    call mem_set_value(this%ipakcb, 'IPAKCB', this%input_mempath, found%ipakcb)
+    call mem_set_value(this%iprpak, 'IPRPAK', this%input_mempath, found%iprpak)
+    call mem_set_value(this%iprflow, 'IPRFLOW', this%input_mempath, found%iprflow)
+    call mem_set_value(this%inamedbound, 'BOUNDNAMES', this%input_mempath, &
+                       found%boundnames)
+    call mem_set_value(this%dev_ifmod_on, 'DEV_IFMOD_ON', this%input_mempath, &
+                       found%dev_ifmod_on)
+    !
+    ! -- reallocate aux arrays if aux variables provided
+    if (found%naux .and. this%naux > 0) then
       call mem_reallocate(this%auxname, LENAUXNAME, this%naux, &
                           'AUXNAME', this%memoryPath)
       call mem_reallocate(this%auxname_cst, LENAUXNAME, this%naux, &
                           'AUXNAME_CST', this%memoryPath)
+      call mem_set_value(this%auxname_cst, 'AUXILIARY', this%input_mempath, &
+                         found%auxiliary)
+      !
       do n = 1, this%naux
-        this%auxname(n) = caux(n)
-        this%auxname_cst(n) = caux(n)
+        this%auxname(n) = this%auxname_cst(n)
       end do
-      deallocate (caux)
       !
       ! -- If ANGLDEGX is an auxiliary variable, then anisotropy can be
       !    used in either model.  Store ANGLDEGX position in this%ianglex
@@ -115,250 +132,329 @@ function parse_option(this, keyword, iout) result(parsed)
       if (ival > 0) then
         this%ianglex = ival
       end if
+      !
       ival = ifind(this%auxname, 'CDIST')
       if (ival > 0) then
         this%icdist = ival
       end if
-    case ('PRINT_INPUT')
-      this%iprpak = 1
+    end if
+    !
+    if (found%ipakcb) then
+      this%ipakcb = -1
+      write (iout, '(4x,a)') &
+        'EXCHANGE FLOWS WILL BE SAVED TO BINARY BUDGET FILES.'
+    end if
+    !
+    if (found%iprpak) then
       write (iout, '(4x,a)') &
         'THE LIST OF EXCHANGES WILL BE PRINTED.'
-    case ('XT3D')
-      this%ixt3d = 1
-      write (iout, '(4x,a)') 'XT3D WILL BE APPLIED ON THE INTERFACE'
-    case ('BOUNDNAMES')
-      this%inamedbound = 1
+    end if
+    !
+    if (found%iprflow) then
+      write (iout, '(4x,a)') &
+        'EXCHANGE FLOWS WILL BE PRINTED TO LIST FILES.'
+    end if
+    !
+    if (found%boundnames) then
       write (iout, '(4x,a)') 'EXCHANGE BOUNDARIES HAVE NAMES IN LAST COLUMN'
-    case ('DEV_INTERFACEMODEL_ON')
-      call this%parser%DevOpt()
-      this%dev_ifmod_on = .true.
+    end if
+    !
+    if (found%dev_ifmod_on) then
       write (iout, '(4x,2a)') 'Interface model coupling approach manually &
         &activated for ', trim(this%name)
-    case default
-      ! not parsed here, assuming it is in derived type
-      parsed = .false.
-    end select
-
-  end function parse_option
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine source_options
 
-  !> @brief Read dimensions from file
+  !> @brief Source dimension from input context
   !<
-  subroutine read_dimensions(this, iout)
-    use ConstantsModule, only: LINELENGTH
-    use SimModule, only: store_error
+  subroutine source_dimensions(this, iout)
+    ! -- modules
+    use MemoryManagerExtModule, only: mem_set_value
+    ! -- dummy
     class(DisConnExchangeType) :: this !< instance of exchange object
-    integer(I4B), intent(in) :: iout !< output file unit
-    ! local
-    character(len=LINELENGTH) :: keyword
-    integer(I4B) :: ierr
-    logical :: isfound, endOfBlock
-
-    ! get dimensions block
-    call this%parser%GetBlock('DIMENSIONS', isfound, ierr, &
-                              supportOpenClose=.true.)
+    integer(I4B), intent(in) :: iout !< for logging
+    ! -- local
+    type(DisConnExchangeFoundType) :: found
+    !
+    ! -- update defaults with idm sourced values
+    call mem_set_value(this%nexg, 'NEXG', this%input_mempath, found%nexg)
+    !
+    write (iout, '(1x,a)') 'PROCESSING EXCHANGE DIMENSIONS'
+    !
+    if (found%nexg) then
+      write (iout, '(4x,a,i0)') 'NEXG = ', this%nexg
+    end if
+    !
+    write (iout, '(1x,a)') 'END OF EXCHANGE DIMENSIONS'
+    !
+    ! -- return
+    return
+  end subroutine source_dimensions
 
-    ! parse NEXG
-    if (isfound) then
-      write (iout, '(1x,a)') 'PROCESSING EXCHANGE DIMENSIONS'
-      do
-        call this%parser%GetNextLine(endOfBlock)
-        if (endOfBlock) exit
-        call this%parser%GetStringCaps(keyword)
-        select case (keyword)
-        case ('NEXG')
-          this%nexg = this%parser%GetInteger()
-          write (iout, '(4x,a,i0)') 'NEXG = ', this%nexg
-        case default
-          errmsg = "Unknown dimension '"//trim(keyword)//"'."
-          call store_error(errmsg)
-          call this%parser%StoreErrorUnit()
-        end select
-      end do
-      write (iout, '(1x,a)') 'END OF EXCHANGE DIMENSIONS'
+  !> @brief Returns reduced node number from user
+  !< specified cell id.
+  function noder(this, model, cellid, iout)
+    ! -- modules
+    use GeomUtilModule, only: get_node
+    ! -- dummy
+    class(DisConnExchangeType) :: this !< instance of exchange object
+    class(NumericalModelType), pointer, intent(in) :: model
+    integer(I4B), dimension(:), pointer, intent(in) :: cellid
+    integer(I4B), intent(in) :: iout !< the output file unit
+    integer(I4B) :: noder, node
+    !
+    if (model%dis%ndim == 1) then
+      node = cellid(1)
+    elseif (model%dis%ndim == 2) then
+      node = get_node(cellid(1), 1, cellid(2), &
+                      model%dis%mshape(1), 1, &
+                      model%dis%mshape(2))
     else
-      call store_error('Required dimensions block not found.')
-      call this%parser%StoreErrorUnit()
+      node = get_node(cellid(1), cellid(2), cellid(3), &
+                      model%dis%mshape(1), &
+                      model%dis%mshape(2), &
+                      model%dis%mshape(3))
     end if
+    noder = model%dis%get_nodenumber(node, 0)
+    !
+    ! -- return
+    return
+  end function noder
 
+  !> @brief
+  !<
+  function cellstr(this, ndim, cellid, iout)
+    ! -- modules
+    ! -- dummy
+    class(DisConnExchangeType) :: this !< instance of exchange object
+    integer(I4B) :: ndim !< model DIS dimension
+    integer(I4B), dimension(:), pointer, intent(in) :: cellid
+    integer(I4B), intent(in) :: iout !< the output file unit
+    character(len=20) :: cellstr
+    character(len=*), parameter :: fmtndim1 = &
+                                   "('(',i0,')')"
+    character(len=*), parameter :: fmtndim2 = &
+                                   "('(',i0,',',i0,')')"
+    character(len=*), parameter :: fmtndim3 = &
+                                   "('(',i0,',',i0,',',i0,')')"
+    !
+    cellstr = ''
+    !
+    select case (ndim)
+    case (1)
+      write (cellstr, fmtndim1) cellid(1)
+    case (2)
+      write (cellstr, fmtndim2) cellid(1), cellid(2)
+    case (3)
+      write (cellstr, fmtndim3) cellid(1), cellid(2), cellid(3)
+    case default
+    end select
+    !
+    ! -- return
     return
-  end subroutine read_dimensions
+  end function cellstr
 
-  !> @brief Read exchange data block from file
+  !> @brief Source exchange data from input context
   !<
-  subroutine read_data(this, iout)
-    use ConstantsModule, only: LINELENGTH
-    use SimModule, only: store_error, store_error_unit, count_errors
+  subroutine source_data(this, iout)
+    ! -- modules
+    use MemoryManagerModule, only: mem_setptr
+    ! -- dummy
     class(DisConnExchangeType) :: this !< instance of exchange object
     integer(I4B), intent(in) :: iout !< the output file unit
-    ! local
-    character(len=20) :: cellid1, cellid2
+    ! -- local
+    integer(I4B), dimension(:, :), contiguous, pointer :: cellidm1
+    integer(I4B), dimension(:, :), contiguous, pointer :: cellidm2
+    integer(I4B), dimension(:), contiguous, pointer :: ihc
+    real(DP), dimension(:), contiguous, pointer :: cl1
+    real(DP), dimension(:), contiguous, pointer :: cl2
+    real(DP), dimension(:), contiguous, pointer :: hwva
+    real(DP), dimension(:, :), contiguous, pointer :: auxvar
+    type(CharacterStringType), dimension(:), contiguous, pointer :: boundname
+    integer(I4B) :: ndim1, ndim2
+    character(len=20) :: cellstr1, cellstr2
     character(len=2) :: cnfloat
-    integer(I4B) :: lloc, ierr, nerr, iaux
+    integer(I4B) :: nerr, iaux
     integer(I4B) :: iexg, nodem1, nodem2
-    logical :: isfound, endOfBlock
-
-    character(len=*), parameter :: fmtexglabel = "(5x, 3a10, 50(a16))"
+    ! -- format
+    character(len=*), parameter :: fmtexglabel = "(1x, 3a10, 50(a16))"
     character(len=*), parameter :: fmtexgdata = &
                                    "(5x, a, 1x, a ,I10, 50(1pg16.6))"
     character(len=40) :: fmtexgdata2
-
-    ! get data block
-    call this%parser%GetBlock('EXCHANGEDATA', isfound, ierr, &
-                              supportOpenClose=.true.)
-    if (isfound) then
-      write (iout, '(1x,a)') 'PROCESSING EXCHANGEDATA'
-      if (this%iprpak /= 0) then
-        if (this%inamedbound == 0) then
-          write (iout, fmtexglabel) 'NODEM1', 'NODEM2', 'IHC', &
-            'CL1', 'CL2', 'HWVA', (adjustr(this%auxname(iaux)), &
-                                   iaux=1, this%naux)
-        else
-          write (iout, fmtexglabel) 'NODEM1', 'NODEM2', 'IHC', 'CL1', 'CL2', &
-            'HWVA', (adjustr(this%auxname(iaux)), iaux=1, this%naux), &
-            ' BOUNDNAME      '
-          ! Define format suitable for writing input data,
-          ! any auxiliary variables, and boundname.
-          write (cnfloat, '(i0)') 3 + this%naux
-          fmtexgdata2 = '(5x, a, 1x, a, i10, '//trim(cnfloat)// &
-                        '(1pg16.6), 1x, a)'
-        end if
+    !
+    call mem_setptr(cellidm1, 'CELLIDM1', this%input_mempath)
+    call mem_setptr(cellidm2, 'CELLIDM2', this%input_mempath)
+    call mem_setptr(ihc, 'IHC', this%input_mempath)
+    call mem_setptr(cl1, 'CL1', this%input_mempath)
+    call mem_setptr(cl2, 'CL2', this%input_mempath)
+    call mem_setptr(hwva, 'HWVA', this%input_mempath)
+    call mem_setptr(auxvar, 'AUX', this%input_mempath)
+    call mem_setptr(boundname, 'BOUNDNAME', this%input_mempath)
+    ndim1 = size(cellidm1, dim=1)
+    ndim2 = size(cellidm2, dim=1)
+    !
+    write (iout, '(1x,a)') 'PROCESSING EXCHANGEDATA'
+    !
+    if (this%iprpak /= 0) then
+      if (this%inamedbound == 0) then
+        write (iout, fmtexglabel) 'NODEM1', 'NODEM2', 'IHC', &
+          'CL1', 'CL2', 'HWVA', (adjustr(this%auxname(iaux)), &
+                                 iaux=1, this%naux)
+      else
+        write (iout, fmtexglabel) 'NODEM1', 'NODEM2', 'IHC', 'CL1', 'CL2', &
+          'HWVA', (adjustr(this%auxname(iaux)), iaux=1, this%naux), &
+          ' BOUNDNAME      '
+        ! Define format suitable for writing input data,
+        ! any auxiliary variables, and boundname.
+        write (cnfloat, '(i0)') 3 + this%naux
+        fmtexgdata2 = '(5x, a, 1x, a, i10, '//trim(cnfloat)// &
+                      '(1pg16.6), 1x, a)'
       end if
-      do iexg = 1, this%nexg
-        call this%parser%GetNextLine(endOfBlock)
-        lloc = 1
-        !
-        ! -- Read and check node 1
-        call this%parser%GetCellid(this%v_model1%dis_ndim%get(), cellid1, &
-                                   flag_string=.true.)
-        if (associated(this%model1)) then
-          nodem1 = this%model1%dis%noder_from_cellid(cellid1, &
-                                                     this%parser%iuactive, &
-                                                     iout, flag_string=.true.)
-          this%nodem1(iexg) = nodem1
-        else
-          this%nodem1(iexg) = -1
-        end if
-        !
-        ! -- Read and check node 2
-        call this%parser%GetCellid(this%v_model2%dis_ndim%get(), cellid2, &
-                                   flag_string=.true.)
-        if (associated(this%model2)) then
-          nodem2 = this%model2%dis%noder_from_cellid(cellid2, &
-                                                     this%parser%iuactive, &
-                                                     iout, flag_string=.true.)
-          this%nodem2(iexg) = nodem2
-        else
-          this%nodem2(iexg) = -1
-        end if
+    end if
+    !
+    do iexg = 1, this%nexg
+      !
+      if (associated(this%model1)) then
         !
-        ! -- Read rest of input line
-        this%ihc(iexg) = this%parser%GetInteger()
-        this%cl1(iexg) = this%parser%GetDouble()
-        this%cl2(iexg) = this%parser%GetDouble()
-        this%hwva(iexg) = this%parser%GetDouble()
-        do iaux = 1, this%naux
-          this%auxvar(iaux, iexg) = this%parser%GetDouble()
-        end do
-        if (this%inamedbound == 1) then
-          call this%parser%GetStringCaps(this%boundname(iexg))
-        end if
+        ! -- Determine reduced node number
+        nodem1 = this%noder(this%model1, cellidm1(:, iexg), iout)
+        this%nodem1(iexg) = nodem1
         !
-        ! -- Write the data to listing file if requested
-        if (this%iprpak /= 0) then
-          if (this%inamedbound == 0) then
-            write (iout, fmtexgdata) trim(cellid1), trim(cellid2), &
-              this%ihc(iexg), this%cl1(iexg), this%cl2(iexg), &
-              this%hwva(iexg), &
-              (this%auxvar(iaux, iexg), iaux=1, this%naux)
-          else
-            write (iout, fmtexgdata2) trim(cellid1), trim(cellid2), &
-              this%ihc(iexg), this%cl1(iexg), this%cl2(iexg), &
-              this%hwva(iexg), &
-              (this%auxvar(iaux, iexg), iaux=1, this%naux), &
-              trim(this%boundname(iexg))
-          end if
-        end if
+      else
+        this%nodem1(iexg) = -1
+      end if
+      !
+      if (associated(this%model2)) then
         !
-        ! -- Check to see if nodem1 is outside of active domain
-        if (associated(this%model1)) then
-          if (nodem1 <= 0) then
-            write (errmsg, *) &
-              trim(adjustl(this%model1%name))// &
-              ' Cell is outside active grid domain ('// &
-              trim(adjustl(cellid1))//').'
-            call store_error(errmsg)
-          end if
-        end if
+        ! -- Determine reduced node number
+        nodem2 = this%noder(this%model2, cellidm2(:, iexg), iout)
+        this%nodem2(iexg) = nodem2
         !
-        ! -- Check to see if nodem2 is outside of active domain
-        if (associated(this%model2)) then
-          if (nodem2 <= 0) then
-            write (errmsg, *) &
-              trim(adjustl(this%model2%name))// &
-              ' Cell is outside active grid domain ('// &
-              trim(adjustl(cellid2))//').'
-            call store_error(errmsg)
-          end if
-        end if
+      else
+        this%nodem2(iexg) = -1
+      end if
+      !
+      ! -- Read rest of input line
+      this%ihc(iexg) = ihc(iexg)
+      this%cl1(iexg) = cl1(iexg)
+      this%cl2(iexg) = cl2(iexg)
+      this%hwva(iexg) = hwva(iexg)
+      do iaux = 1, this%naux
+        this%auxvar(iaux, iexg) = auxvar(iaux, iexg)
       end do
+      if (this%inamedbound == 1) then
+        this%boundname(iexg) = boundname(iexg)
+      end if
       !
-      ! -- Stop if errors
-      nerr = count_errors()
-      if (nerr > 0) then
-        call store_error('Errors encountered in exchange input file.')
-        call this%parser%StoreErrorUnit()
+      ! -- Write the data to listing file if requested
+      if (this%iprpak /= 0) then
+        cellstr1 = this%cellstr(ndim1, cellidm1(:, iexg), iout)
+        cellstr2 = this%cellstr(ndim2, cellidm2(:, iexg), iout)
+        if (this%inamedbound == 0) then
+          write (iout, fmtexgdata) trim(cellstr1), trim(cellstr2), &
+            this%ihc(iexg), this%cl1(iexg), this%cl2(iexg), &
+            this%hwva(iexg), &
+            (this%auxvar(iaux, iexg), iaux=1, this%naux)
+        else
+          write (iout, fmtexgdata2) trim(cellstr1), trim(cellstr2), &
+            this%ihc(iexg), this%cl1(iexg), this%cl2(iexg), &
+            this%hwva(iexg), &
+            (this%auxvar(iaux, iexg), iaux=1, this%naux), &
+            trim(this%boundname(iexg))
+        end if
       end if
       !
-      write (iout, '(1x,a)') 'END OF EXCHANGEDATA'
-    else
-      errmsg = 'Required exchangedata block not found.'
-      call store_error(errmsg)
-      call this%parser%StoreErrorUnit()
+      ! -- Check to see if nodem1 is outside of active domain
+      if (associated(this%model1)) then
+        if (nodem1 <= 0) then
+          cellstr1 = this%cellstr(ndim1, cellidm1(:, iexg), iout)
+          write (errmsg, *) &
+            trim(adjustl(this%model1%name))// &
+            ' Cell is outside active grid domain ('// &
+            trim(adjustl(cellstr1))//').'
+          call store_error(errmsg)
+        end if
+      end if
+      !
+      ! -- Check to see if nodem2 is outside of active domain
+      if (associated(this%model2)) then
+        if (nodem2 <= 0) then
+          cellstr2 = this%cellstr(ndim2, cellidm2(:, iexg), iout)
+          write (errmsg, *) &
+            trim(adjustl(this%model2%name))// &
+            ' Cell is outside active grid domain ('// &
+            trim(adjustl(cellstr2))//').'
+          call store_error(errmsg)
+        end if
+      end if
+    end do
+    !
+    write (iout, '(1x,a)') 'END OF EXCHANGEDATA'
+    !
+    ! -- Stop if errors
+    nerr = count_errors()
+    if (nerr > 0) then
+      call store_error('Errors encountered in exchange input file.')
+      call store_error_filename(this%filename)
     end if
     !
-    ! -- return
+    ! -- Return
     return
-  end subroutine read_data
+  end subroutine source_data
 
   !> @brief Allocate scalars and initialize to defaults
   !<
   subroutine allocate_scalars(this)
+    ! -- modules
     use MemoryManagerModule, only: mem_allocate
+    ! -- dummy
     class(DisConnExchangeType) :: this !< instance of exchange object
-
+    !
     allocate (this%filename)
     this%filename = ''
-
+    !
     call mem_allocate(this%nexg, 'NEXG', this%memoryPath)
     call mem_allocate(this%naux, 'NAUX', this%memoryPath)
     call mem_allocate(this%ianglex, 'IANGLEX', this%memoryPath)
     call mem_allocate(this%icdist, 'ICDIST', this%memoryPath)
     call mem_allocate(this%ixt3d, 'IXT3D', this%memoryPath)
     call mem_allocate(this%iprpak, 'IPRPAK', this%memoryPath)
+    call mem_allocate(this%iprflow, 'IPRFLOW', this%memoryPath)
+    call mem_allocate(this%ipakcb, 'IPAKCB', this%memoryPath)
     call mem_allocate(this%inamedbound, 'INAMEDBOUND', this%memoryPath)
+    call mem_allocate(this%dev_ifmod_on, 'DEV_IFMOD_ON', this%memoryPath)
 
     call mem_allocate(this%auxname, LENAUXNAME, 0, &
                       'AUXNAME', this%memoryPath)
     call mem_allocate(this%auxname_cst, LENAUXNAME, 0, &
                       'AUXNAME_CST', this%memoryPath)
-
+    !
     this%nexg = 0
     this%naux = 0
     this%ianglex = 0
     this%icdist = 0
     this%ixt3d = 0
+    this%iprpak = 0
+    this%iprflow = 0
+    this%ipakcb = 0
     this%inamedbound = 0
-
+    !
     this%dev_ifmod_on = .false.
-
+    !
+    ! -- Return
+    return
   end subroutine allocate_scalars
 
   !> @brief Allocate array data, using the number of
   !! connected nodes @param nexg
   !<
   subroutine allocate_arrays(this)
+    ! -- dummy
     class(DisConnExchangeType) :: this !< instance of exchange object
-
+    !
     call mem_allocate(this%nodem1, this%nexg, 'NODEM1', this%memoryPath)
     call mem_allocate(this%nodem2, this%nexg, 'NODEM2', this%memoryPath)
     call mem_allocate(this%ihc, this%nexg, 'IHC', this%memoryPath)
@@ -368,7 +464,7 @@ subroutine allocate_arrays(this)
     ! NB: auxname array is allocated while parsing
     call mem_allocate(this%auxvar, this%naux, this%nexg, &
                       'AUXVAR', this%memoryPath)
-
+    !
     ! allocate boundname
     if (this%inamedbound == 1) then
       allocate (this%boundname(this%nexg))
@@ -376,28 +472,36 @@ subroutine allocate_arrays(this)
       allocate (this%boundname(1))
     end if
     this%boundname(:) = ''
-
+    !
+    ! -- Return
+    return
   end subroutine allocate_arrays
 
   !> @brief Should interface model be used to handle these
   !! exchanges, to be overridden for inheriting types
   !<
   function use_interface_model(this) result(use_im)
+    ! -- dummy
     class(DisConnExchangeType) :: this !< instance of exchange object
+    ! -- return
     logical(LGP) :: use_im !< flag whether interface model should be used
                           !! for this exchange instead
-
+    !
     ! use im when one of the models is not local
     use_im = .not. (this%v_model1%is_local .and. this%v_model2%is_local)
-
+    !
+    ! -- Return
+    return
   end function use_interface_model
 
   !> @brief Clean up all scalars and arrays
   !<
   subroutine disconnex_da(this)
+    ! -- modules
     use MemoryManagerModule, only: mem_deallocate
+    ! -- dummy
     class(DisConnExchangeType) :: this !< instance of exchange object
-
+    !
     ! arrays
     call mem_deallocate(this%nodem1)
     call mem_deallocate(this%nodem2)
@@ -406,9 +510,9 @@ subroutine disconnex_da(this)
     call mem_deallocate(this%cl2)
     call mem_deallocate(this%hwva)
     call mem_deallocate(this%auxvar)
-
+    !
     deallocate (this%boundname)
-
+    !
     ! scalars
     call mem_deallocate(this%nexg)
     call mem_deallocate(this%naux)
@@ -418,13 +522,20 @@ subroutine disconnex_da(this)
     call mem_deallocate(this%icdist)
     call mem_deallocate(this%ixt3d)
     call mem_deallocate(this%iprpak)
+    call mem_deallocate(this%iprflow)
+    call mem_deallocate(this%ipakcb)
     call mem_deallocate(this%inamedbound)
-
+    call mem_deallocate(this%dev_ifmod_on)
+    !
+    ! -- Return
+    return
   end subroutine disconnex_da
 
   function CastAsDisConnExchangeClass(obj) result(res)
     implicit none
+    ! -- dummy
     class(*), pointer, intent(inout) :: obj
+    ! -- return
     class(DisConnExchangeType), pointer :: res
     !
     res => null()
@@ -434,6 +545,8 @@ function CastAsDisConnExchangeClass(obj) result(res)
     class is (DisConnExchangeType)
       res => obj
     end select
+    !
+    ! -- Return
     return
   end function CastAsDisConnExchangeClass
 
@@ -448,6 +561,7 @@ subroutine AddDisConnExchangeToList(list, exchange)
     obj => exchange
     call list%Add(obj)
     !
+    ! -- Return
     return
   end subroutine AddDisConnExchangeToList
 
@@ -456,6 +570,7 @@ function GetDisConnExchangeFromList(list, idx) result(res)
     ! -- dummy
     type(ListType), intent(inout) :: list
     integer(I4B), intent(in) :: idx
+    ! -- return
     class(DisConnExchangeType), pointer :: res
     ! -- local
     class(*), pointer :: obj
@@ -463,6 +578,7 @@ function GetDisConnExchangeFromList(list, idx) result(res)
     obj => list%GetItem(idx)
     res => CastAsDisConnExchangeClass(obj)
     !
+    ! -- Return
     return
   end function GetDisConnExchangeFromList
 
diff --git a/src/Exchange/GhostNode.f90 b/src/Exchange/GhostNode.f90
index d6e124cf1f7..fa5267ba83d 100644
--- a/src/Exchange/GhostNode.f90
+++ b/src/Exchange/GhostNode.f90
@@ -32,7 +32,9 @@ module GhostNodeModule
     integer(I4B), dimension(:), pointer, contiguous :: idiagm => null() ! amat diagonal position of m
     integer(I4B), dimension(:, :), pointer, contiguous :: jposinrown => null() ! amat j position in row n
     integer(I4B), dimension(:, :), pointer, contiguous :: jposinrowm => null() ! amat j position in row m
+
   contains
+
     procedure :: gnc_df
     procedure :: gnc_ac
     procedure :: gnc_mc
@@ -53,20 +55,14 @@ module GhostNodeModule
 
 contains
 
+  !> @brief Create new GNC exchange object
+  !<
   subroutine gnc_cr(gncobj, name_parent, inunit, iout)
-! ******************************************************************************
-! gnc_cr -- Create new GNC exchange object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     type(GhostNodeType), pointer, intent(inout) :: gncobj
     character(len=*), intent(in) :: name_parent
     integer(I4B), intent(in) :: inunit
     integer(I4B), intent(in) :: iout
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate the gnc exchange object
     allocate (gncobj)
@@ -82,17 +78,13 @@ subroutine gnc_cr(gncobj, name_parent, inunit, iout)
     gncobj%inunit = inunit
     gncobj%iout = iout
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gnc_cr
 
+  !> @brief Initialize a gnc object
+  !<
   subroutine gnc_df(this, m1, m2)
-! ******************************************************************************
-! gnc_df -- Initialize a gnc object.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use NumericalModelModule, only: NumericalModelType
     use SimModule, only: store_error, store_error_unit
@@ -101,8 +93,6 @@ subroutine gnc_df(this, m1, m2)
     class(GhostNodeType) :: this
     class(NumericalModelType), target :: m1
     class(NumericalModelType), target, optional :: m2
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- Point or set attributes
     this%m1 => m1
@@ -139,18 +129,15 @@ subroutine gnc_df(this, m1, m2)
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gnc_df
 
+  !> @brief Single or Two-Model GNC Add Connections
+  !!
+  !! For implicit GNC, expand the sparse solution matrix
+  !<
   subroutine gnc_ac(this, sparse)
-! ******************************************************************************
-! gnc_ac -- Single or Two-Model GNC Add Connections
-! Subroutine: (1) For implicit GNC, expand the sparse solution matrix
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SparseModule, only: sparsematrix
     ! -- dummy
@@ -158,7 +145,6 @@ subroutine gnc_ac(this, sparse)
     type(sparsematrix), intent(inout) :: sparse
     ! -- local
     integer(I4B) :: ignc, jidx, noden, nodem, nodej
-! ------------------------------------------------------------------------------
     !
     ! -- Expand the sparse matrix for ghost node connections.  No need to add
     !    connection between n and m as they must be connected some other way
@@ -179,23 +165,20 @@ subroutine gnc_ac(this, sparse)
       end do
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gnc_ac
 
+  !> @brief Single or Two-Model GNC Map Connections
+  !!
+  !! Fill the following mapping arrays:
+  !!  this%idiagn, this%idiagm (diagonal positions in solution amat)
+  !!  this%idxglo (nm connection in solution amat)
+  !!  this%idxsymglo (mn connection in solution amat)
+  !!  this%jposinrown (position of j in row n of solution amat)
+  !!  this%jposinrowm (position of j in row m of solution amat)
+  !<
   subroutine gnc_mc(this, matrix_sln)
-! ******************************************************************************
-! gnc_mc -- Single or Two-Model GNC Map Connections
-! Subroutine: (1) Fill the following mapping arrays:
-!                 this%idiagn, this%idiagm (diagonal positions in solution amat)
-!                 this%idxglo (nm connection in solution amat)
-!                 this%idxsymglo (mn connection in solution amat)
-!                 this%jposinrown (position of j in row n of solution amat)
-!                 this%jposinrowm (position of j in row m of solution amat)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SimModule, only: store_error, store_error_unit, count_errors
     use SimVariablesModule, only: errmsg
@@ -208,7 +191,6 @@ subroutine gnc_mc(this, matrix_sln)
     character(len=*), parameter :: fmterr = &
       "('GHOST NODE ERROR.  Cell ', i0, ' in model ', a, &
         &' is not connected to cell ', i0, ' in model ', a)"
-! ------------------------------------------------------------------------------
     !
     ! -- Find the location of Cnm in the global solution and store it in
     !    this%idxglo
@@ -271,18 +253,14 @@ subroutine gnc_mc(this, matrix_sln)
       end do
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gnc_mc
 
+  !> @brief Store the n-m Picard conductance in cond prior to the Newton terms
+  !! terms being added
+  !<
   subroutine gnc_fmsav(this, kiter, matrix)
-! ******************************************************************************
-! gnc_fmsav -- Store the n-m Picard conductance in cond prior to the Newton
-!   terms being added.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DZERO
     ! -- dummy
@@ -292,7 +270,6 @@ subroutine gnc_fmsav(this, kiter, matrix)
     ! -- local
     integer(I4B) :: ignc, ipos
     real(DP) :: cond
-! ------------------------------------------------------------------------------
     !
     ! -- An ipos value of zero indicates that noden is not connected to
     !    nodem, and therefore the conductance is zero.
@@ -306,19 +283,16 @@ subroutine gnc_fmsav(this, kiter, matrix)
       this%cond(ignc) = cond
     end do gncloop
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gnc_fmsav
 
+  !> @brief Fill matrix terms
+  !!
+  !! Add the GNC terms to the solution matrix or model rhs depending on whether
+  !! whether GNC is implicit or explicit
+  !<
   subroutine gnc_fc(this, kiter, matrix)
-! ******************************************************************************
-! gnc_fc -- Fill matrix terms
-! Subroutine: (1) Add the GNC terms to the solution matrix or model rhs depending
-!                 on whether GNC is implicit or explicit
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DZERO
     ! -- dummy
@@ -328,7 +302,6 @@ subroutine gnc_fc(this, kiter, matrix)
     ! -- local
     integer(I4B) :: ignc, j, noden, nodem, ipos, jidx, iposjn, iposjm
     real(DP) :: cond, alpha, aterm, rterm
-! ------------------------------------------------------------------------------
     !
     ! -- If this is a single model gnc (not an exchange across models), then
     !    pull conductances out of the system matrix and store them in this%cond
@@ -364,30 +337,26 @@ subroutine gnc_fc(this, kiter, matrix)
       end do jloop
     end do gncloop
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gnc_fc
 
+  !> @brief Fill GNC Newton terms
+  !!
+  !! Required arguments:
+  !!  kiter : outer iteration number
+  !!  matrix_sln: the solution matrix
+  !!  condsat is of size(njas) if single model, otherwise nexg
+  !!
+  !! Optional arguments:
+  !!   ihc_opt : an optional vector of size(nexg), which contains a horizontal
+  !!     connection code (0=vertical, 1=horizontal, 2=vertically staggered)
+  !!   ivarcv_opt : variable vertical conductance flag (default is 0)
+  !!   ictm1_opt : icelltype for model 1 integer vector (default is 1)
+  !!   ictm2_opt : icelltype for model 2 integer vector (default is 1)
+  !<
   subroutine gnc_fn(this, kiter, matrix_sln, condsat, ihc_opt, &
                     ivarcv_opt, ictm1_opt, ictm2_opt)
-! ******************************************************************************
-! gnc_fn -- Fill GNC Newton terms
-!
-!  Required arguments:
-!   kiter : outer iteration number
-!   matrix_sln: the solution matrix
-!   condsat is of size(njas) if single model, otherwise nexg
-!
-!  Optional arguments:
-!    ihc_opt : an optional vector of size(nexg), which contains a horizontal
-!      connection code (0=vertical, 1=horizontal, 2=vertically staggered)
-!    ivarcv_opt : variable vertical conductance flag (default is 0)
-!    ictm1_opt : icelltype for model 1 integer vector (default is 1)
-!    ictm2_opt : icelltype for model 2 integer vector (default is 1)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DZERO
     use SmoothingModule, only: sQuadraticSaturationDerivative
@@ -406,7 +375,6 @@ subroutine gnc_fn(this, kiter, matrix_sln, condsat, ihc_opt, &
     integer(I4B) :: iups, ictup
     real(DP) :: csat, alpha, consterm, term, derv
     real(DP) :: xup, topup, botup
-! ------------------------------------------------------------------------------
     !
     ! -- Set the ivarcv to indicate whether or not the vertical conductance
     !    is a function of water table
@@ -491,18 +459,15 @@ subroutine gnc_fn(this, kiter, matrix_sln, condsat, ihc_opt, &
       end do jloop
     end do gncloop
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gnc_fn
 
+  !> @brief Single Model GNC Output
+  !!
+  !! Output GNC deltaQgnc values
+  !<
   subroutine gnc_ot(this, ibudfl)
-! ******************************************************************************
-! gnc_ot -- Single Model GNC Output
-! Subroutine: (1) Output GNC deltaQgnc values
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GhostNodeType) :: this
     integer(I4B), intent(in) :: ibudfl
@@ -512,7 +477,6 @@ subroutine gnc_ot(this, ibudfl)
     character(len=LINELENGTH) :: nodenstr, nodemstr
     ! -- format
     character(len=*), parameter :: fmtgnc = "(i10, 2a10, 2(1pg15.6))"
-! ------------------------------------------------------------------------------
     !
     ! -- Process each gnc and output deltaQgnc
     if (ibudfl /= 0 .and. this%iprflow /= 0) then
@@ -529,25 +493,19 @@ subroutine gnc_ot(this, ibudfl)
       end do
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gnc_ot
 
+  !> @brief Add GNC to flowja
+  !<
   subroutine gnc_cq(this, flowja)
-! ******************************************************************************
-! gnc_cq -- Add GNC to flowja
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GhostNodeType) :: this
     real(DP), dimension(:), intent(inout) :: flowja
     ! -- local
     integer(I4B) :: ignc, n1, n2, ipos, isympos
     real(DP) :: deltaQgnc
-    ! -- format
-! ------------------------------------------------------------------------------
     !
     ! -- go through each gnc and add deltagnc to flowja
     do ignc = 1, this%nexg
@@ -567,21 +525,18 @@ subroutine gnc_cq(this, flowja)
       !
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gnc_cq
 
+  !> @brief Single Model deltaQgnc (ghost node correction flux)
+  !!
+  !! Calculate the deltaQgnc value for any GNC in the GNC list
+  !<
   function deltaQgnc(this, ignc)
-! ******************************************************************************
-! deltaQgnc -- Single Model deltaQgnc (ghost node correction flux)
-! Subroutine: (1) Calculate the deltaQgnc value for any GNC in the GNC list
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DZERO
-    ! -- return
+    ! -- Return
     real(DP) :: deltaQgnc
     ! -- dummy
     class(GhostNodeType) :: this
@@ -589,7 +544,6 @@ function deltaQgnc(this, ignc)
     ! -- local
     integer(I4B) :: noden, nodem, nodej, jidx
     real(DP) :: sigalj, alpha, hd, aterm, cond
-! ------------------------------------------------------------------------------
     !
     ! -- initialize values
     deltaQgnc = DZERO
@@ -613,22 +567,17 @@ function deltaQgnc(this, ignc)
       deltaQgnc = aterm * cond
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end function deltaQgnc
 
+  !> @brief Allocate gnc scalar variables
+  !<
   subroutine allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars -- allocate gnc scalar variables
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GhostNodeType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- allocate scalars in NumericalPackageType
     call this%NumericalPackageType%allocate_scalars()
@@ -646,22 +595,17 @@ subroutine allocate_scalars(this)
     this%nexg = 0
     this%numjs = 0
     !
+    ! -- Return
     return
   end subroutine allocate_scalars
 
+  !> @brief Allocate gnc scalar variables
+  !<
   subroutine allocate_arrays(this)
-! ******************************************************************************
-! allocate_arrays -- allocate gnc scalar variables
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GhostNodeType) :: this
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- allocate memory for arrays
     call mem_allocate(this%nodem1, this%nexg, 'NODEM1', this%memoryPath)
@@ -689,18 +633,13 @@ subroutine allocate_arrays(this)
     return
   end subroutine allocate_arrays
 
+  !> @brief Deallocate memory
+  !<
   subroutine gnc_da(this)
-! ******************************************************************************
-! gnc_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(GhostNodeType) :: this
-! ------------------------------------------------------------------------------
     !
     call mem_deallocate(this%smgnc)
     call mem_deallocate(this%implicit)
@@ -730,14 +669,11 @@ subroutine gnc_da(this)
     return
   end subroutine gnc_da
 
+  !> @brief Read a gnc options block
+  !!
+  !! Read options from input file
+  !<
   subroutine read_options(this)
-! ******************************************************************************
-! read_options -- read a gnc options block
-! Subroutine: (1) read options from input file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SimModule, only: store_error
     use SimVariablesModule, only: errmsg
@@ -747,7 +683,6 @@ subroutine read_options(this)
     character(len=LINELENGTH) :: keyword
     integer(I4B) :: ierr
     logical :: isfound, endOfBlock
-! ------------------------------------------------------------------------------
     !
     ! -- get options block
     call this%parser%GetBlock('OPTIONS', isfound, ierr, &
@@ -789,18 +724,15 @@ subroutine read_options(this)
     ! -- Set the iasym flag if the correction is implicit
     if (this%implicit) this%iasym = 1
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine read_options
 
+  !> @brief Single Model GNC Read Dimensions
+  !!
+  !! Read dimensions (size of gnc list) from input file
+  !<
   subroutine read_dimensions(this)
-! ******************************************************************************
-! read_dimensions -- Single Model GNC Read Dimensions
-! Subroutine: (1) read dimensions (size of gnc list) from input file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SimModule, only: store_error
     use SimVariablesModule, only: errmsg
@@ -810,7 +742,6 @@ subroutine read_dimensions(this)
     character(len=LINELENGTH) :: keyword
     integer(I4B) :: ierr
     logical :: isfound, endOfBlock
-! ------------------------------------------------------------------------------
     !
     ! -- get options block
     call this%parser%GetBlock('DIMENSIONS', isfound, ierr, &
@@ -842,18 +773,15 @@ subroutine read_dimensions(this)
       call store_error('Required DIMENSIONS block not found.', terminate=.TRUE.)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine read_dimensions
 
+  !> @brief Read a GNCDATA block
+  !!
+  !! Read list of GNCs from input file
+  !<
   subroutine read_data(this)
-! ******************************************************************************
-! read_data -- Read a GNCDATA block
-! Subroutine: (1) read list of GNCs from input file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SimModule, only: store_error, count_errors
     use SimVariablesModule, only: errmsg
@@ -866,8 +794,6 @@ subroutine read_data(this)
     integer(I4B) :: ignc, jidx, nodeun, nodeum, nerr
     integer(I4B), dimension(:), allocatable :: nodesuj
     logical :: isfound, endOfBlock
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- Construct the fmtgnc format
     write (fmtgnc, '("(2i10,",i0,"i10,",i0, "(1pg15.6))")') this%numjs, &
@@ -981,17 +907,13 @@ subroutine read_data(this)
     ! -- deallocate nodesuj array
     deallocate (nodesuj)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine read_data
 
+  !> @brief Convert the user-based node number into a reduced number
+  !<
   subroutine nodeu_to_noder(this, nodeu, noder, model)
-! ******************************************************************************
-! nodeu_to_noder -- Convert the user-based node number into a reduced number
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use NumericalModelModule, only: NumericalModelType
     use SimModule, only: store_error
@@ -1001,8 +923,6 @@ subroutine nodeu_to_noder(this, nodeu, noder, model)
     integer(I4B), intent(in) :: nodeu
     integer(I4B), intent(inout) :: noder
     class(NumericalModelType), intent(in) :: model
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     if (nodeu < 1 .or. nodeu > model%dis%nodesuser) then
       write (errmsg, *) &
diff --git a/src/Exchange/GwfExchangeMover.f90 b/src/Exchange/GwfExchangeMover.f90
new file mode 100644
index 00000000000..6c132343551
--- /dev/null
+++ b/src/Exchange/GwfExchangeMover.f90
@@ -0,0 +1,286 @@
+module GwfExgMoverModule
+  use KindModule, only: I4B, DP, LGP
+  use ConstantsModule, only: LENMODELNAME, LENPACKAGENAME, DZERO, DNODATA
+  use MemoryManagerModule, only: mem_allocate, mem_deallocate
+  use MemoryHelperModule, only: split_mem_path
+  use VirtualModelModule
+  use BaseDisModule
+  use GwfMvrModule
+  use PackageMoverModule, only: PackageMoverType, set_packagemover_pointer
+  implicit none
+  private
+
+  public :: exg_mvr_cr
+
+  !> @brief Extends model mover for exchanges to also handle the
+  !< parallel case where the models are not on the same process.
+  type, public, extends(GwfMvrType) :: GwfExgMoverType
+    class(VirtualModelType), pointer :: model1 => null() !< virtual model 1
+    class(VirtualModelType), pointer :: model2 => null() !< virtual model 2
+    logical(LGP), dimension(:), pointer, contiguous :: prov_is_m1 => null() !< .true. when the providing package is part of model 1
+    real(DP), dimension(:), pointer, contiguous :: qpactual_m1 => null() !< stores qpactual for synchronization when provider is in model 1
+    real(DP), dimension(:), pointer, contiguous :: qpactual_m2 => null() !< stores qpactual for synchronization when provider is in model 2
+    real(DP), dimension(:), pointer, contiguous :: qavailable_m1 => null() !< stores qavailable for synchronization when provider is in model 1
+    real(DP), dimension(:), pointer, contiguous :: qavailable_m2 => null() !< stores qavailable for synchronization when provider is in model 2
+    integer(I4B), dimension(:), pointer, contiguous :: id_mapped_m1 => null() !< stores the mapped feature ids for synchronization when provider is in model 1
+    integer(I4B), dimension(:), pointer, contiguous :: id_mapped_m2 => null() !< stores the mapped feature ids for synchronization when provider is in model 2
+  contains
+    procedure :: mvr_da => xmvr_da
+    procedure :: xmvr_cf
+    procedure :: mvr_fc => xmvr_fc
+    procedure :: mvr_bd => xmvr_bd
+    procedure :: check_packages => xmvr_check_packages
+    procedure :: assign_packagemovers => xmvr_assign_packagemovers
+    procedure :: initialize_movers => xmvr_initialize_movers
+    procedure :: allocate_arrays => xmvr_allocate_arrays
+  end type
+
+contains
+
+  subroutine exg_mvr_cr(exg_mvr, name_parent, inunit, iout, dis)
+    class(GwfExgMoverType), pointer :: exg_mvr
+    character(len=*), intent(in) :: name_parent
+    integer(I4B), intent(in) :: inunit
+    integer(I4B), intent(in) :: iout
+    class(DisBaseType), pointer :: dis
+
+    allocate (exg_mvr)
+
+    ! Init through base
+    call exg_mvr%mvr_init(name_parent, inunit, iout, dis, 1)
+
+  end subroutine exg_mvr_cr
+
+  subroutine xmvr_check_packages(this)
+    use ConstantsModule, only: LINELENGTH
+    use MemoryManagerModule, only: mem_setptr
+    use SimModule, only: store_error, count_errors, store_error_unit
+    class(GwfExgMoverType), intent(inout) :: this
+    ! local
+    character(len=LENMODELNAME) :: mname
+    character(len=LENPACKAGENAME) :: pname
+    class(VirtualModelType), pointer :: vm
+    character(len=LINELENGTH) :: errmsg
+    integer(I4B) :: i
+    integer(I4B), pointer :: imover_ptr
+
+    do i = 1, size(this%pckMemPaths)
+      ! check only when local
+      call split_mem_path(this%pckMemPaths(i), mname, pname)
+      vm => get_virtual_model(mname)
+      if (vm%is_local) then
+        ! check if PackageMover is active in package:
+        imover_ptr => null()
+        call mem_setptr(imover_ptr, 'IMOVER', trim(this%pckMemPaths(i)))
+        if (imover_ptr == 0) then
+          write (errmsg, '(a, a, a)') &
+            'ERROR.  MODEL AND PACKAGE "', &
+            trim(this%pckMemPaths(i)), &
+            '" DOES NOT HAVE MOVER SPECIFIED IN OPTIONS BLOCK.'
+          call store_error(errmsg)
+        end if
+      end if
+    end do
+
+    if (count_errors() > 0) then
+      call this%parser%StoreErrorUnit()
+    end if
+
+  end subroutine xmvr_check_packages
+
+  !> @brief Overrides GWF MVR routine to skip assigning
+  !< pointers when the package is not local
+  subroutine xmvr_assign_packagemovers(this)
+    class(GwfExgMoverType), intent(inout) :: this !< this exchange mover
+    ! local
+    integer(I4B) :: i
+    character(len=LENMODELNAME) :: mname
+    character(len=LENPACKAGENAME) :: pname
+    class(VirtualModelType), pointer :: vm
+
+    do i = 1, size(this%pckMemPaths)
+      if (this%pakmovers(i)%memoryPath == '') then
+        ! is it local?
+        call split_mem_path(this%pckMemPaths(i), mname, pname)
+        vm => get_virtual_model(mname)
+        if (vm%is_local) then
+          ! yes, we need the pointers
+          call set_packagemover_pointer(this%pakmovers(i), &
+                                        trim(this%pckMemPaths(i)))
+        end if
+      end if
+    end do
+  end subroutine xmvr_assign_packagemovers
+
+  !> @brief Overrides mover initialization in GWF MVR to
+  !! deactivate remote parts and build up sync. arrays
+  !< for mapped feature ids
+  subroutine xmvr_initialize_movers(this, nr_active_movers)
+    class(GwfExgMoverType) :: this
+    integer(I4B) :: nr_active_movers
+    ! local
+    integer(I4B) :: i
+    character(len=LENMODELNAME) :: mname
+    character(len=LENPACKAGENAME) :: pname
+    class(VirtualModelType), pointer :: vm
+    class(PackageMoverType), allocatable :: pkg_mvr
+
+    call this%GwfMvrType%initialize_movers(nr_active_movers)
+
+    this%prov_is_m1 = .false.
+
+    ! deactivate remote parts
+    do i = 1, nr_active_movers
+      call split_mem_path(this%mvr(i)%mem_path_src, mname, pname)
+      vm => get_virtual_model(mname)
+      this%mvr(i)%is_provider_active = vm%is_local
+      this%prov_is_m1(i) = associated(vm, this%model1)
+      call split_mem_path(this%mvr(i)%mem_path_tgt, mname, pname)
+      vm => get_virtual_model(mname)
+      this%mvr(i)%is_receiver_active = vm%is_local
+    end do
+
+    ! loop over mvr's, if provider is active,
+    ! store mapped feature index in array for sync
+    allocate (pkg_mvr)
+
+    do i = 1, nr_active_movers
+      if (this%mvr(i)%is_provider_active) then
+        ! store mapped feature id in array (for synchronization when parallel)
+        call set_packagemover_pointer(pkg_mvr, this%mvr(i)%mem_path_src)
+        if (this%prov_is_m1(i)) then
+          this%id_mapped_m1(i) = pkg_mvr%iprmap(this%mvr(i)%iRchNrSrc)
+          this%id_mapped_m2(i) = -1
+        else
+          this%id_mapped_m1(i) = -1
+          this%id_mapped_m2(i) = pkg_mvr%iprmap(this%mvr(i)%iRchNrSrc)
+        end if
+      end if
+    end do
+
+  end subroutine xmvr_initialize_movers
+
+  !> @brief Calculates qpactual and stores it for synchronization
+  !<
+  subroutine xmvr_cf(this)
+    class(GwfExgMoverType) :: this
+    ! local
+    integer(I4B) :: i
+
+    do i = 1, this%nmvr
+      if (this%mvr(i)%is_provider_active) then
+
+        call this%mvr(i)%update_provider()
+
+        ! copy calculated rate to arrays for synchronization:
+        if (this%prov_is_m1(i)) then
+          this%qpactual_m1(i) = this%mvr(i)%qpactual
+          this%qavailable_m1(i) = this%mvr(i)%qavailable
+          this%qpactual_m2(i) = DNODATA
+          this%qavailable_m2(i) = DNODATA
+        else
+          this%qpactual_m1(i) = DNODATA
+          this%qavailable_m1(i) = DNODATA
+          this%qpactual_m2(i) = this%mvr(i)%qpactual
+          this%qavailable_m2(i) = this%mvr(i)%qavailable
+        end if
+      end if
+    end do
+
+  end subroutine xmvr_cf
+
+  !> @brief Assign synced qpactual to mover and update receiver
+  !<
+  subroutine xmvr_fc(this)
+    class(GwfExgMoverType) :: this
+    ! local
+    integer(I4B) :: i
+
+    do i = 1, this%nmvr
+      ! TODO_MJR: this should only be around the update call,
+      ! such that every mover has a valid qpactual ??!!
+      if (this%mvr(i)%is_receiver_active) then
+
+        ! copy from synchronization arrays back into movers:
+        if (this%prov_is_m1(i)) then
+          this%mvr(i)%qpactual = this%qpactual_m1(i)
+          this%mvr(i)%qavailable = this%qavailable_m1(i)
+        else
+          this%mvr(i)%qpactual = this%qpactual_m2(i)
+          this%mvr(i)%qavailable = this%qavailable_m2(i)
+        end if
+
+        call this%mvr(i)%update_receiver()
+      end if
+    end do
+
+  end subroutine xmvr_fc
+
+  !> @brief Overrides budget routine to first assign the
+  !< mapped features ids from the synchronization arrays
+  subroutine xmvr_bd(this)
+    class(GwfExgMoverType) :: this
+    ! local
+    integer(I4B) :: i
+
+    ! copy from synchronization arrays back into movers:
+    do i = 1, this%nmvr
+      if (this%prov_is_m1(i)) then
+        this%mvr(i)%iRchNrSrcMapped = this%id_mapped_m1(i)
+      else
+        this%mvr(i)%iRchNrSrcMapped = this%id_mapped_m2(i)
+      end if
+    end do
+
+    call this%fill_budobj()
+
+  end subroutine xmvr_bd
+
+  subroutine xmvr_allocate_arrays(this)
+    class(GwfExgMoverType) :: this
+    ! local
+    integer(I4B) :: i
+
+    call this%GwfMvrType%allocate_arrays()
+
+    allocate (this%prov_is_m1(this%maxmvr))
+    call mem_allocate(this%qpactual_m1, this%maxmvr, 'QPACTUAL_M1', &
+                      this%memoryPath)
+    call mem_allocate(this%qpactual_m2, this%maxmvr, 'QPACTUAL_M2', &
+                      this%memoryPath)
+    call mem_allocate(this%qavailable_m1, this%maxmvr, 'QAVAILABLE_M1', &
+                      this%memoryPath)
+    call mem_allocate(this%qavailable_m2, this%maxmvr, 'QAVAILABLE_M2', &
+                      this%memoryPath)
+    call mem_allocate(this%id_mapped_m1, this%maxmvr, 'ID_MAPPED_M1', &
+                      this%memoryPath)
+    call mem_allocate(this%id_mapped_m2, this%maxmvr, 'ID_MAPPED_M2', &
+                      this%memoryPath)
+
+    do i = 1, this%maxmvr
+      this%id_mapped_m1(i) = 0
+      this%id_mapped_m2(i) = 0
+      this%qpactual_m1(i) = DNODATA
+      this%qpactual_m2(i) = DNODATA
+      this%qavailable_m1(i) = DNODATA
+      this%qavailable_m2(i) = DNODATA
+    end do
+
+  end subroutine xmvr_allocate_arrays
+
+  subroutine xmvr_da(this)
+    class(GwfExgMoverType) :: this
+
+    call this%GwfMvrType%mvr_da()
+
+    deallocate (this%prov_is_m1)
+    call mem_deallocate(this%qpactual_m1)
+    call mem_deallocate(this%qpactual_m2)
+    call mem_deallocate(this%qavailable_m1)
+    call mem_deallocate(this%qavailable_m2)
+    call mem_deallocate(this%id_mapped_m1)
+    call mem_deallocate(this%id_mapped_m2)
+
+  end subroutine xmvr_da
+
+end module GwfExgMoverModule
diff --git a/src/Exchange/GwfGwfExchange.f90 b/src/Exchange/GwfGwfExchange.f90
index ad89b404457..c501c52501f 100644
--- a/src/Exchange/GwfGwfExchange.f90
+++ b/src/Exchange/GwfGwfExchange.f90
@@ -11,9 +11,11 @@ module GwfGwfExchangeModule
 
   use KindModule, only: DP, I4B, LGP
   use SimVariablesModule, only: errmsg
-  use SimModule, only: store_error
+  use SimModule, only: count_errors, store_error, store_error_filename, &
+                       store_error_unit
   use BaseModelModule, only: BaseModelType, GetBaseModelFromList
   use BaseExchangeModule, only: BaseExchangeType, AddBaseExchangeToList
+  use BaseDisModule, only: DisBaseType
   use ConstantsModule, only: LENBOUNDNAME, NAMEDBOUNDFLAG, LINELENGTH, &
                              TABCENTER, TABLEFT, LENAUXNAME, DNODATA
   use ListModule, only: ListType
@@ -22,12 +24,10 @@ module GwfGwfExchangeModule
   use GwfModule, only: GwfModelType
   use VirtualModelModule, only: VirtualModelType
   use GhostNodeModule, only: GhostNodeType
-  use GwfMvrModule, only: GwfMvrType
+  use GwfExgMoverModule, only: GwfExgMoverType
   use ObserveModule, only: ObserveType
   use ObsModule, only: ObsType
-  use SimModule, only: count_errors, store_error, store_error_unit
   use SimVariablesModule, only: errmsg, model_loc_idx
-  use BlockParserModule, only: BlockParserType
   use TableModule, only: TableType, table_cr
   use MatrixBaseModule
 
@@ -43,15 +43,12 @@ module GwfGwfExchangeModule
   !!
   !! This derived type contains information and methods for
   !! connecting two GWF models.
-  !!
   !<
   type, extends(DisConnExchangeType) :: GwfExchangeType
-    type(GwfModelType), pointer :: gwfmodel1 => null() !< pointer to GWF Model 1
-    type(GwfModelType), pointer :: gwfmodel2 => null() !< pointer to GWF Model 2
+    class(GwfModelType), pointer :: gwfmodel1 => null() !< pointer to GWF Model 1
+    class(GwfModelType), pointer :: gwfmodel2 => null() !< pointer to GWF Model 2
     !
     ! -- GWF specific option block:
-    integer(I4B), pointer :: iprflow => null() !< print flag for cell by cell flows
-    integer(I4B), pointer :: ipakcb => null() !< save flag for cell by cell flows
     integer(I4B), pointer :: inewton => null() !< newton flag (1 newton is on)
     integer(I4B), pointer :: icellavg => null() !< cell averaging
     integer(I4B), pointer :: ivarcv => null() !< variable cv
@@ -59,7 +56,7 @@ module GwfGwfExchangeModule
     integer(I4B), pointer :: ingnc => null() !< unit number for gnc (0 if off)
     type(GhostNodeType), pointer :: gnc => null() !< gnc object
     integer(I4B), pointer :: inmvr => null() !< unit number for mover (0 if off)
-    type(GwfMvrType), pointer :: mvr => null() !< water mover object
+    class(GwfExgMoverType), pointer :: mvr => null() !< water mover object
     integer(I4B), pointer :: inobs => null() !< unit number for GWF-GWF observations
     type(ObsType), pointer :: obs => null() !< observation object
     !
@@ -96,14 +93,14 @@ module GwfGwfExchangeModule
     procedure :: use_interface_model
     procedure :: allocate_scalars
     procedure :: allocate_arrays
-    procedure :: read_options
-    procedure :: parse_option
+    procedure :: source_options
     procedure :: read_gnc
     procedure :: read_mvr
     procedure, private :: calc_cond_sat
     procedure, private :: condcalc
     procedure, private :: rewet
     procedure, private :: qcalc
+    procedure, private :: gwf_gwf_chd_bd
     procedure :: gwf_gwf_bdsav
     procedure, private :: gwf_gwf_bdsav_model
     procedure, private :: gwf_gwf_df_obs
@@ -119,10 +116,10 @@ module GwfGwfExchangeModule
 
   !> @ brief Create GWF GWF exchange
   !!
-  !< Create a new GWF to GWF exchange object.
-  subroutine gwfexchange_create(filename, name, id, m1_id, m2_id)
+  !! Create a new GWF to GWF exchange object.
+  !<
+  subroutine gwfexchange_create(filename, name, id, m1_id, m2_id, input_mempath)
     ! -- modules
-    use ConstantsModule, only: LINELENGTH
     use BaseModelModule, only: BaseModelType
     use VirtualModelModule, only: get_virtual_model
     use ListsModule, only: baseexchangelist
@@ -134,6 +131,7 @@ subroutine gwfexchange_create(filename, name, id, m1_id, m2_id)
     integer(I4B), intent(in) :: id !< id for the exchange
     integer(I4B), intent(in) :: m1_id !< id for model 1
     integer(I4B), intent(in) :: m2_id !< id for model 2
+    character(len=*), intent(in) :: input_mempath
     ! -- local
     type(GwfExchangeType), pointer :: exchange
     class(BaseModelType), pointer :: mb
@@ -149,6 +147,7 @@ subroutine gwfexchange_create(filename, name, id, m1_id, m2_id)
     exchange%id = id
     exchange%name = name
     exchange%memoryPath = create_mem_path(exchange%name)
+    exchange%input_mempath = input_mempath
     !
     ! -- allocate scalars and set defaults
     call exchange%allocate_scalars()
@@ -199,14 +198,13 @@ subroutine gwfexchange_create(filename, name, id, m1_id, m2_id)
     ! -- Create the obs package
     call obs_cr(exchange%obs, exchange%inobs)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwfexchange_create
 
   !> @ brief Define GWF GWF exchange
   !!
   !! Define GWF to GWF exchange object.
-  !!
   !<
   subroutine gwf_gwf_df(this)
     ! -- modules
@@ -216,38 +214,31 @@ subroutine gwf_gwf_df(this)
     ! -- dummy
     class(GwfExchangeType) :: this !<  GwfExchangeType
     ! -- local
-    integer(I4B) :: inunit
     !
-    ! -- open the file
-    inunit = getunit()
+    ! -- log the exchange
     write (iout, '(/a,a)') ' Creating exchange: ', this%name
-    call openfile(inunit, iout, this%filename, 'GWF-GWF')
-    !
-    call this%parser%Initialize(inunit, iout)
     !
     ! -- Ensure models are in same solution
-    if (associated(this%gwfmodel1) .and. associated(this%gwfmodel2)) then
-      if (this%gwfmodel1%idsoln /= this%gwfmodel2%idsoln) then
-        call store_error('Two models are connected in a GWF '// &
-                         'exchange but they are in different solutions. '// &
-                         'GWF models must be in same solution: '// &
-                         trim(this%gwfmodel1%name)//' '// &
-                         trim(this%gwfmodel2%name))
-        call this%parser%StoreErrorUnit()
-      end if
+    if (this%v_model1%idsoln%get() /= this%v_model2%idsoln%get()) then
+      call store_error('Two models are connected in a GWF '// &
+                       'exchange but they are in different solutions. '// &
+                       'GWF models must be in same solution: '// &
+                       trim(this%v_model1%name)//' '// &
+                       trim(this%v_model2%name))
+      call store_error_filename(this%filename)
     end if
     !
-    ! -- read options
-    call this%read_options(iout)
+    ! -- source options
+    call this%source_options(iout)
     !
-    ! -- read dimensions
-    call this%read_dimensions(iout)
+    ! -- source dimensions
+    call this%source_dimensions(iout)
     !
     ! -- allocate arrays
     call this%allocate_arrays()
     !
-    ! -- read exchange data
-    call this%read_data(iout)
+    ! -- source exchange data
+    call this%source_data(iout)
     !
     ! -- call each model and increase the edge count
     if (associated(this%gwfmodel1)) then
@@ -268,9 +259,6 @@ subroutine gwf_gwf_df(this)
       call this%read_mvr(iout)
     end if
     !
-    ! -- close the file
-    close (inunit)
-    !
     ! -- Store obs
     call this%gwf_gwf_df_obs()
     if (associated(this%gwfmodel1)) then
@@ -280,19 +268,20 @@ subroutine gwf_gwf_df(this)
     ! -- validate
     call this%validate_exchange()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwf_gwf_df
 
   !> @brief validate exchange data after reading
   !<
   subroutine validate_exchange(this)
+    ! -- modules
     class(GwfExchangeType) :: this !<  GwfExchangeType
-    ! local
+    ! -- local
     logical(LGP) :: has_k22, has_spdis, has_vsc
-
+    !
     ! Periodic boundary condition in exchange don't allow XT3D (=interface model)
-    if (associated(this%model1, this%model2)) then
+    if (this%v_model1 == this%v_model2) then
       if (this%ixt3d > 0) then
         write (errmsg, '(3a)') 'GWF-GWF exchange ', trim(this%name), &
           ' is a periodic boundary condition which cannot'// &
@@ -300,7 +289,7 @@ subroutine validate_exchange(this)
         call store_error(errmsg, terminate=.TRUE.)
       end if
     end if
-
+    !
     ! XT3D needs angle information
     if (this%ixt3d > 0 .and. this%ianglex == 0) then
       write (errmsg, '(3a)') 'GWF-GWF exchange ', trim(this%name), &
@@ -308,7 +297,7 @@ subroutine validate_exchange(this)
         ' auxiliary variable because XT3D is enabled'
       call store_error(errmsg, terminate=.TRUE.)
     end if
-
+    !
     ! determine if specific functionality is demanded,
     ! in model 1 or model 2 (in parallel, only one of
     ! the models is checked, but the exchange is duplicated)
@@ -325,7 +314,7 @@ subroutine validate_exchange(this)
       has_spdis = has_spdis .or. (this%gwfmodel2%npf%icalcspdis /= 0)
       has_vsc = has_vsc .or. (this%gwfmodel2%npf%invsc /= 0)
     end if
-
+    !
     ! If horizontal anisotropy is in either model1 or model2,
     ! ANGLDEGX must be provided as an auxiliary variable for this
     ! GWF-GWF exchange (this%ianglex > 0).
@@ -338,7 +327,7 @@ subroutine validate_exchange(this)
         call store_error(errmsg, terminate=.TRUE.)
       end if
     end if
-
+    !
     ! If specific discharge is needed for model1 or model2,
     ! ANGLDEGX must be provided as an auxiliary variable for this
     ! GWF-GWF exchange (this%ianglex > 0).
@@ -360,7 +349,7 @@ subroutine validate_exchange(this)
         call store_error(errmsg, terminate=.TRUE.)
       end if
     end if
-
+    !
     ! If viscosity is on in either model, then terminate with an
     ! error as viscosity package doesn't work yet with exchanges.
     if (has_vsc) then
@@ -369,13 +358,14 @@ subroutine validate_exchange(this)
         ' in both of the connected models.'
       call store_error(errmsg, terminate=.TRUE.)
     end if
-
+    !
+    ! -- Return
+    return
   end subroutine validate_exchange
 
   !> @ brief Add connections
   !!
-  !! override parent exg_ac so that gnc can add connections here.
-  !!
+  !! Override parent exg_ac so that gnc can add connections here.
   !<
   subroutine gwf_gwf_ac(this, sparse)
     ! -- modules
@@ -406,7 +396,6 @@ end subroutine gwf_gwf_ac
   !> @ brief Map connections
   !!
   !! Map the connections in the global matrix
-  !!
   !<
   subroutine gwf_gwf_mc(this, matrix_sln)
     ! -- modules
@@ -437,10 +426,8 @@ end subroutine gwf_gwf_mc
   !> @ brief Allocate and read
   !!
   !! Allocated and read and calculate saturated conductance
-  !!
   !<
   subroutine gwf_gwf_ar(this)
-    ! -- modules
     ! -- dummy
     class(GwfExchangeType) :: this !<  GwfExchangeType
     !
@@ -460,7 +447,6 @@ end subroutine gwf_gwf_ar
   !> @ brief Read and prepare
   !!
   !! Read new data for mover and obs
-  !!
   !<
   subroutine gwf_gwf_rp(this)
     ! -- modules
@@ -484,13 +470,10 @@ end subroutine gwf_gwf_rp
   !> @ brief Advance
   !!
   !! Advance mover and obs
-  !!
   !<
   subroutine gwf_gwf_ad(this)
-    ! -- modules
     ! -- dummy
     class(GwfExchangeType) :: this !<  GwfExchangeType
-    ! -- local
     !
     ! -- Advance mover
     if (this%inmvr > 0) call this%mvr%mvr_ad()
@@ -505,7 +488,6 @@ end subroutine gwf_gwf_ad
   !> @ brief Calculate coefficients
   !!
   !! Rewet as necessary
-  !!
   !<
   subroutine gwf_gwf_cf(this, kiter)
     ! -- dummy
@@ -513,6 +495,9 @@ subroutine gwf_gwf_cf(this, kiter)
     integer(I4B), intent(in) :: kiter
     ! -- local
     !
+    ! -- Call mvr fc routine
+    if (this%inmvr > 0) call this%mvr%xmvr_cf()
+    !
     ! -- Rewet cells across models using the wetdry parameters in each model's
     !    npf package, and the head in the connected model.
     call this%rewet(kiter)
@@ -524,7 +509,6 @@ end subroutine gwf_gwf_cf
   !> @ brief Fill coefficients
   !!
   !! Calculate conductance and fill coefficient matrix
-  !!
   !<
   subroutine gwf_gwf_fc(this, kiter, matrix_sln, rhs_sln, inwtflag)
     ! -- modules
@@ -596,7 +580,6 @@ end subroutine gwf_gwf_fc
   !> @ brief Fill Newton
   !!
   !! Fill amatsln with Newton terms
-  !!
   !<
   subroutine gwf_gwf_fn(this, kiter, matrix_sln)
     ! -- modules
@@ -707,16 +690,13 @@ end subroutine gwf_gwf_fn
   !!
   !! Calculate flow between two cells and store in simvals, also set
   !! information needed for specific discharge calculation
-  !!
   !<
   subroutine gwf_gwf_cq(this, icnvg, isuppress_output, isolnid)
-    ! -- modules
     ! -- dummy
     class(GwfExchangeType) :: this !<  GwfExchangeType
     integer(I4B), intent(inout) :: icnvg
     integer(I4B), intent(in) :: isuppress_output
     integer(I4B), intent(in) :: isolnid
-    ! -- local
     !
     ! -- calculate flow and store in simvals
     call this%gwf_gwf_calc_simvals()
@@ -727,21 +707,24 @@ subroutine gwf_gwf_cq(this, icnvg, isuppress_output, isolnid)
     ! -- add exchange flows to model's flowja diagonal
     call this%gwf_gwf_add_to_flowja()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwf_gwf_cq
 
-  !> @brief Calculate flow rates for the exchanges and
-  !< store them in a member array
+  !> @brief Calculate flow rates for the exchanges and store them in a member
+  !! array
+  !<
   subroutine gwf_gwf_calc_simvals(this)
+    ! -- modules
     use ConstantsModule, only: DZERO
+    ! -- dummy
     class(GwfExchangeType) :: this !<  GwfExchangeType
-    ! local
+    ! -- local
     integer(I4B) :: i
     integer(I4B) :: n1, n2
     integer(I4B) :: ibdn1, ibdn2
     real(DP) :: rrate
-
+    !
     do i = 1, this%nexg
       rrate = DZERO
       n1 = this%nodem1(i)
@@ -756,48 +739,58 @@ subroutine gwf_gwf_calc_simvals(this)
       end if
       this%simvals(i) = rrate
     end do
-
+    !
+    ! -- Return
     return
   end subroutine gwf_gwf_calc_simvals
 
-  !> @brief Add exchange flow to each model flowja diagonal
-  !< position so that residual is calculated correctly.
+  !> @brief Add exchange flow to each model flowja diagonal position so that
+  !! residual is calculated correctly.
+  !<
   subroutine gwf_gwf_add_to_flowja(this)
+    ! -- modules
     class(GwfExchangeType) :: this !<  GwfExchangeType
-    ! local
+    ! -- local
     integer(I4B) :: i
     integer(I4B) :: n
     integer(I4B) :: idiag
     real(DP) :: flow
-
+    !
     do i = 1, this%nexg
-
+      !
       if (associated(this%gwfmodel1)) then
-        flow = this%simvals(i)
         n = this%nodem1(i)
-        idiag = this%gwfmodel1%ia(n)
-        this%gwfmodel1%flowja(idiag) = this%gwfmodel1%flowja(idiag) + flow
+        if (this%gwfmodel1%ibound(n) > 0) then
+          flow = this%simvals(i)
+          idiag = this%gwfmodel1%ia(n)
+          this%gwfmodel1%flowja(idiag) = this%gwfmodel1%flowja(idiag) + flow
+        end if
       end if
-
+      !
       if (associated(this%gwfmodel2)) then
-        flow = -this%simvals(i)
         n = this%nodem2(i)
-        idiag = this%gwfmodel2%ia(n)
-        this%gwfmodel2%flowja(idiag) = this%gwfmodel2%flowja(idiag) + flow
+        if (this%gwfmodel2%ibound(n) > 0) then
+          flow = -this%simvals(i)
+          idiag = this%gwfmodel2%ia(n)
+          this%gwfmodel2%flowja(idiag) = this%gwfmodel2%flowja(idiag) + flow
+        end if
       end if
-
+      !
     end do
-
+    !
+    ! -- Return
     return
   end subroutine gwf_gwf_add_to_flowja
 
   !> @brief Set flow rates to the edges in the models
   !<
   subroutine gwf_gwf_set_flow_to_npf(this)
+    ! -- modules
     use ConstantsModule, only: DZERO, DPIO180
     use GwfNpfModule, only: thksatnm
+    ! -- dummy
     class(GwfExchangeType) :: this !<  GwfExchangeType
-    ! local
+    ! -- local
     integer(I4B) :: iusg
     integer(I4B) :: i
     integer(I4B) :: n1, n2
@@ -816,7 +809,7 @@ subroutine gwf_gwf_set_flow_to_npf(this)
     real(DP) :: area
     real(DP) :: thksat
     real(DP) :: angle
-
+    !
     ! -- Return if there neither model needs to calculate specific discharge
     if (this%gwfmodel1%npf%icalcspdis == 0 .and. &
         this%gwfmodel2%npf%icalcspdis == 0) return
@@ -901,13 +894,13 @@ subroutine gwf_gwf_set_flow_to_npf(this)
       !
     end do
     !
+    ! -- Return
     return
   end subroutine gwf_gwf_set_flow_to_npf
 
   !> @ brief Budget
   !!
   !! Accumulate budget terms
-  !!
   !<
   subroutine gwf_gwf_bd(this, icnvg, isuppress_output, isolnid)
     ! -- modules
@@ -922,7 +915,6 @@ subroutine gwf_gwf_bd(this, icnvg, isuppress_output, isolnid)
     character(len=LENBUDTXT), dimension(1) :: budtxt
     real(DP), dimension(2, 1) :: budterm
     real(DP) :: ratin, ratout
-    ! -- formats
     !
     ! -- initialize
     budtxt(1) = '    FLOW-JA-FACE'
@@ -944,20 +936,88 @@ subroutine gwf_gwf_bd(this, icnvg, isuppress_output, isolnid)
       call this%gwfmodel2%model_bdentry(budterm, budtxt, this%name)
     end if
     !
+    ! -- Add any flows from one model into a constant head in another model
+    !    as a separate budget term called FLOW-JA-FACE-CHD
+    call this%gwf_gwf_chd_bd()
+    !
     ! -- Call mvr bd routine
     if (this%inmvr > 0) call this%mvr%mvr_bd()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwf_gwf_bd
 
+  !> @ brief gwf-gwf-chd-bd
+  !!
+  !! Account for flow from an external model into a chd cell
+  !<
+  subroutine gwf_gwf_chd_bd(this)
+    ! -- modules
+    use ConstantsModule, only: DZERO, LENBUDTXT, LENPACKAGENAME
+    use BudgetModule, only: rate_accumulator
+    ! -- dummy
+    class(GwfExchangeType) :: this !<  GwfExchangeType
+    ! -- local
+    character(len=LENBUDTXT), dimension(1) :: budtxt
+    integer(I4B) :: n
+    integer(I4B) :: i
+    real(DP), dimension(2, 1) :: budterm
+    real(DP) :: ratin, ratout
+    real(DP) :: q
+    !
+    ! -- initialize
+    budtxt(1) = 'FLOW-JA-FACE-CHD'
+    !
+    ! -- Add the constant-head budget terms for flow from model 2 into model 1
+    if (associated(this%gwfmodel1)) then
+      ratin = DZERO
+      ratout = DZERO
+      do i = 1, this%nexg
+        n = this%nodem1(i)
+        if (this%gwfmodel1%ibound(n) < 0) then
+          q = this%simvals(i)
+          if (q > DZERO) then
+            ratout = ratout + q
+          else
+            ratin = ratin - q
+          end if
+        end if
+      end do
+      budterm(1, 1) = ratin
+      budterm(2, 1) = ratout
+      call this%gwfmodel1%model_bdentry(budterm, budtxt, this%name)
+    end if
+    !
+    ! -- Add the constant-head budget terms for flow from model 1 into model 2
+    if (associated(this%gwfmodel2)) then
+      ratin = DZERO
+      ratout = DZERO
+      do i = 1, this%nexg
+        n = this%nodem2(i)
+        if (this%gwfmodel2%ibound(n) < 0) then
+          ! -- flip flow sign as flow is relative to model 1
+          q = -this%simvals(i)
+          if (q > DZERO) then
+            ratout = ratout + q
+          else
+            ratin = ratin - q
+          end if
+        end if
+      end do
+      budterm(1, 1) = ratin
+      budterm(2, 1) = ratout
+      call this%gwfmodel2%model_bdentry(budterm, budtxt, this%name)
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine gwf_gwf_chd_bd
+
   !> @ brief Budget save
   !!
   !! Output individual flows to listing file and binary budget files
-  !!
   !<
   subroutine gwf_gwf_bdsav(this)
-    ! -- modules
     ! -- dummy
     class(GwfExchangeType) :: this !<  GwfExchangeType
     ! -- local
@@ -986,16 +1046,18 @@ subroutine gwf_gwf_bdsav(this)
       call this%gwf_gwf_save_simvals()
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwf_gwf_bdsav
 
   subroutine gwf_gwf_bdsav_model(this, model)
+    ! -- modules
     use ConstantsModule, only: DZERO, LENBUDTXT, LENPACKAGENAME
     use TdisModule, only: kstp, kper
+    ! -- dummy
     class(GwfExchangeType) :: this !< this exchange
-    type(GwfModelType), pointer :: model !< the model to save budget for
-    ! local
+    class(GwfModelType), pointer :: model !< the model to save budget for
+    ! -- local
     character(len=LENPACKAGENAME + 4) :: packname
     character(len=LENBUDTXT), dimension(1) :: budtxt
     type(TableType), pointer :: output_tab
@@ -1008,7 +1070,7 @@ subroutine gwf_gwf_bdsav_model(this, model)
     integer(I4B) :: ibinun
     real(DP) :: ratin, ratout, rrate
     logical(LGP) :: is_for_model1
-
+    !
     budtxt(1) = '    FLOW-JA-FACE'
     packname = 'EXG '//this%name
     packname = adjustr(packname)
@@ -1115,7 +1177,6 @@ subroutine gwf_gwf_bdsav_model(this, model)
               call output_tab%print_list_entry(i, trim(adjustl(nodestr)), &
                                                -rrate, bname)
             end if
-
           end if
         end if
         if (rrate < DZERO) then
@@ -1141,18 +1202,19 @@ subroutine gwf_gwf_bdsav_model(this, model)
       end if
       !
     end do
-
+    !
+    ! -- Return
+    return
   end subroutine gwf_gwf_bdsav_model
 
   !> @ brief Output
   !!
   !! Write output
-  !!
   !<
   subroutine gwf_gwf_ot(this)
     ! -- modules
     use SimVariablesModule, only: iout
-    use ConstantsModule, only: DZERO, LINELENGTH
+    use ConstantsModule, only: DZERO
     ! -- dummy
     class(GwfExchangeType) :: this !<  GwfExchangeType
     ! -- local
@@ -1215,191 +1277,119 @@ subroutine gwf_gwf_ot(this)
     ! -- OBS output
     call this%obs%obs_ot()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwf_gwf_ot
 
-  !> @ brief Read options
-  !!
-  !! Read the options block
+  !> @ brief Source options
   !!
+  !! Source the options block
   !<
-  subroutine read_options(this, iout)
+  subroutine source_options(this, iout)
     ! -- modules
-    use ConstantsModule, only: LINELENGTH, LENAUXNAME, DEM6
-    use MemoryManagerModule, only: mem_allocate
-    use SimModule, only: store_error, store_error_unit
+    use ConstantsModule, only: LENVARNAME, DEM6
+    use InputOutputModule, only: getunit, openfile
+    use MemoryManagerExtModule, only: mem_set_value
+    use CharacterStringModule, only: CharacterStringType
+    use ExgGwfgwfInputModule, only: ExgGwfgwfParamFoundType
+    use SourceCommonModule, only: filein_fname
     ! -- dummy
     class(GwfExchangeType) :: this !<  GwfExchangeType
     integer(I4B), intent(in) :: iout
     ! -- local
-    character(len=LINELENGTH) :: keyword
-    logical :: isfound
-    logical :: endOfBlock
-    integer(I4B) :: ierr
-    !
-    ! -- get options block
-    call this%parser%GetBlock('OPTIONS', isfound, ierr, &
-                              supportOpenClose=.true., blockRequired=.false.)
-    !
-    ! -- parse options block if detected
-    if (isfound) then
-      write (iout, '(1x,a)') 'PROCESSING GWF-GWF EXCHANGE OPTIONS'
-      do
-        call this%parser%GetNextLine(endOfBlock)
-        if (endOfBlock) then
-          exit
-        end if
-        call this%parser%GetStringCaps(keyword)
-
-        ! first parse option in base
-        if (this%DisConnExchangeType%parse_option(keyword, iout)) then
-          cycle
-        end if
-
-        ! it's probably ours
-        if (this%parse_option(keyword, iout)) then
-          cycle
-        end if
-
-        ! unknown option
-        errmsg = "Unknown GWF-GWF exchange option '"//trim(keyword)//"'."
-        call store_error(errmsg)
-        call this%parser%StoreErrorUnit()
-      end do
-
-      write (iout, '(1x,a)') 'END OF GWF-GWF EXCHANGE OPTIONS'
+    type(ExgGwfgwfParamFoundType) :: found
+    character(len=LENVARNAME), dimension(3) :: cellavg_method = &
+      &[character(len=LENVARNAME) :: 'HARMONIC', 'LOGARITHMIC', 'AMT-LMK']
+    character(len=LINELENGTH) :: gnc_fname, mvr_fname
+    !
+    ! -- update defaults with idm sourced values
+    call mem_set_value(this%icellavg, 'CELL_AVERAGING', this%input_mempath, &
+                       cellavg_method, found%cell_averaging)
+    call mem_set_value(this%inewton, 'NEWTON', this%input_mempath, found%newton)
+    call mem_set_value(this%ixt3d, 'XT3D', this%input_mempath, found%xt3d)
+    call mem_set_value(this%ivarcv, 'VARIABLECV', this%input_mempath, &
+                       found%variablecv)
+    call mem_set_value(this%idewatcv, 'DEWATERED', this%input_mempath, &
+                       found%dewatered)
+    !
+    write (iout, '(1x,a)') 'PROCESSING GWF-GWF EXCHANGE OPTIONS'
+    !
+    ! -- source base class options
+    call this%DisConnExchangeType%source_options(iout)
+    !
+    if (found%cell_averaging) then
+      ! -- count from 0
+      this%icellavg = this%icellavg - 1
+      write (iout, '(4x,a,a)') &
+        'CELL AVERAGING METHOD HAS BEEN SET TO: ', &
+        trim(cellavg_method(this%icellavg + 1))
     end if
     !
-    ! -- set omega value used for saturation calculations
-    if (this%inewton > 0) then
-      this%satomega = DEM6
+    if (found%newton) then
+      write (iout, '(4x,a)') &
+        'NEWTON-RAPHSON method used for unconfined cells'
     end if
     !
-    ! -- return
-    return
-  end subroutine read_options
-
-  !> @brief parse option from exchange file
-  !<
-  function parse_option(this, keyword, iout) result(parsed)
-    use InputOutputModule, only: getunit, openfile
-    class(GwfExchangeType) :: this !<  GwfExchangeType
-    character(len=LINELENGTH), intent(in) :: keyword !< the option name
-    integer(I4B), intent(in) :: iout !< for logging
-    logical(LGP) :: parsed !< true when parsed
-    ! local
-    character(len=LINELENGTH) :: fname
-    integer(I4B) :: inobs
-    character(len=LINELENGTH) :: subkey
-    character(len=:), allocatable :: line
-
-    parsed = .true.
-
-    sel_opt:select case(keyword)
-    case ('PRINT_FLOWS')
-    this%iprflow = 1
-    write (iout, '(4x,a)') &
-      'EXCHANGE FLOWS WILL BE PRINTED TO LIST FILES.'
-    case ('SAVE_FLOWS')
-    this%ipakcb = -1
-    write (iout, '(4x,a)') &
-      'EXCHANGE FLOWS WILL BE SAVED TO BINARY BUDGET FILES.'
-    case ('ALTERNATIVE_CELL_AVERAGING')
-    call this%parser%GetStringCaps(subkey)
-    select case (subkey)
-    case ('LOGARITHMIC')
-      this%icellavg = 1
-    case ('AMT-LMK')
-      this%icellavg = 2
-    case default
-      errmsg = "Unknown cell averaging method '"//trim(subkey)//"'."
-      call store_error(errmsg)
-      call this%parser%StoreErrorUnit()
-    end select
-    write (iout, '(4x,a,a)') &
-      'CELL AVERAGING METHOD HAS BEEN SET TO: ', trim(subkey)
-    case ('VARIABLECV')
-    this%ivarcv = 1
-    write (iout, '(4x,a)') &
-      'VERTICAL CONDUCTANCE VARIES WITH WATER TABLE.'
-    call this%parser%GetStringCaps(subkey)
-    if (subkey == 'DEWATERED') then
-      this%idewatcv = 1
+    if (found%xt3d) then
+      write (iout, '(4x,a)') 'XT3D WILL BE APPLIED ON THE INTERFACE'
+    end if
+    !
+    if (found%variablecv) then
+      write (iout, '(4x,a)') &
+        'VERTICAL CONDUCTANCE VARIES WITH WATER TABLE.'
+    end if
+    !
+    if (found%dewatered) then
       write (iout, '(4x,a)') &
         'VERTICAL CONDUCTANCE ACCOUNTS FOR DEWATERED PORTION OF   '// &
         'AN UNDERLYING CELL.'
     end if
-    case ('NEWTON')
-    this%inewton = 1
-    write (iout, '(4x,a)') &
-      'NEWTON-RAPHSON method used for unconfined cells'
-    case ('GNC6')
-    call this%parser%GetStringCaps(subkey)
-    if (subkey /= 'FILEIN') then
-      call store_error('GNC6 keyword must be followed by '// &
-                       '"FILEIN" then by filename.')
-      call this%parser%StoreErrorUnit()
-    end if
-    call this%parser%GetString(fname)
-    if (fname == '') then
-      call store_error('No GNC6 file specified.')
-      call this%parser%StoreErrorUnit()
-    end if
-    this%ingnc = getunit()
-    call openfile(this%ingnc, iout, fname, 'GNC')
-    write (iout, '(4x,a)') &
-      'GHOST NODES WILL BE READ FROM ', trim(fname)
-    case ('MVR6')
-    if (this%is_datacopy) then
-      call this%parser%GetRemainingLine(line)
-      exit sel_opt
-    end if
-    call this%parser%GetStringCaps(subkey)
-    if (subkey /= 'FILEIN') then
-      call store_error('MVR6 keyword must be followed by '// &
-                       '"FILEIN" then by filename.')
-      call this%parser%StoreErrorUnit()
+    !
+    ! -- enforce 0 or 1 GNC6_FILENAME entries in option block
+    if (filein_fname(gnc_fname, 'GNC6_FILENAME', this%input_mempath, &
+                     this%filename)) then
+      this%ingnc = getunit()
+      call openfile(this%ingnc, iout, gnc_fname, 'GNC')
+      write (iout, '(4x,a)') &
+        'GHOST NODES WILL BE READ FROM ', trim(gnc_fname)
     end if
-    call this%parser%GetString(fname)
-    if (fname == '') then
-      call store_error('No MVR6 file specified.')
-      call this%parser%StoreErrorUnit()
+    !
+    ! -- enforce 0 or 1 MVR6_FILENAME entries in option block
+    if (filein_fname(mvr_fname, 'MVR6_FILENAME', this%input_mempath, &
+                     this%filename)) then
+      this%inmvr = getunit()
+      call openfile(this%inmvr, iout, mvr_fname, 'MVR')
+      write (iout, '(4x,a)') &
+        'WATER MOVER INFORMATION WILL BE READ FROM ', trim(mvr_fname)
     end if
-    this%inmvr = getunit()
-    call openfile(this%inmvr, iout, fname, 'MVR')
-    write (iout, '(4x,a)') &
-      'WATER MOVER INFORMATION WILL BE READ FROM ', trim(fname)
-    case ('OBS6')
-    if (this%is_datacopy) then
-      call this%parser%GetRemainingLine(line)
-      exit sel_opt
+    !
+    ! -- enforce 0 or 1 OBS6_FILENAME entries in option block
+    if (.not. this%is_datacopy) then
+      if (filein_fname(this%obs%inputFilename, 'OBS6_FILENAME', &
+                       this%input_mempath, this%filename)) then
+        this%obs%active = .true.
+        this%obs%inUnitObs = GetUnit()
+        call openfile(this%obs%inUnitObs, iout, this%obs%inputFilename, 'OBS')
+      end if
     end if
-    call this%parser%GetStringCaps(subkey)
-    if (subkey /= 'FILEIN') then
-      call store_error('OBS8 keyword must be followed by '// &
-                       '"FILEIN" then by filename.')
-      call this%parser%StoreErrorUnit()
+    !
+    write (iout, '(1x,a)') 'END OF GWF-GWF EXCHANGE OPTIONS'
+    !
+    ! -- set omega value used for saturation calculations
+    if (this%inewton > 0) then
+      this%satomega = DEM6
     end if
-    this%obs%active = .true.
-    call this%parser%GetString(this%obs%inputFilename)
-    inobs = GetUnit()
-    call openfile(inobs, iout, this%obs%inputFilename, 'OBS')
-    this%obs%inUnitObs = inobs
-    case default
-    parsed = .false.
-    end select sel_opt
-
-  end function parse_option
+    !
+    ! -- Return
+    return
+  end subroutine source_options
 
   !> @ brief Read ghost nodes
   !!
   !! Read and process ghost nodes
-  !!
   !<
   subroutine read_gnc(this)
     ! -- modules
-    use SimModule, only: store_error, store_error_unit, count_errors
     use ConstantsModule, only: LINELENGTH
     ! -- dummy
     class(GwfExchangeType) :: this !<  GwfExchangeType
@@ -1447,21 +1437,21 @@ subroutine read_gnc(this)
     ! -- close the file
     close (this%ingnc)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine read_gnc
 
   !> @ brief Read mover
   !!
   !! Read and process movers
-  !!
   !<
   subroutine read_mvr(this, iout)
     ! -- modules
-    use GwfMvrModule, only: mvr_cr
+    use GwfExgMoverModule, only: exg_mvr_cr
     ! -- dummy
     class(GwfExchangeType) :: this !<  GwfExchangeType
     integer(I4B), intent(in) :: iout
+    class(DisBaseType), pointer :: dis
     ! -- local
     !
     ! -- Create and initialize the mover object  Here, dis is set to the one
@@ -1470,8 +1460,15 @@ subroutine read_mvr(this, iout)
     !    the dis object does not convert from reduced to user node numbers.
     !    So in this case, the dis object is just writing unconverted package
     !    numbers to the binary budget file.
-    call mvr_cr(this%mvr, this%name, this%inmvr, iout, this%gwfmodel1%dis, &
-                iexgmvr=1)
+    dis => null()
+    if (this%v_model1%is_local) then
+      dis => this%gwfmodel1%dis
+    else if (this%v_model2%is_local) then
+      dis => this%gwfmodel2%dis
+    end if
+    call exg_mvr_cr(this%mvr, this%name, this%inmvr, iout, dis)
+    this%mvr%model1 => this%v_model1
+    this%mvr%model2 => this%v_model2
     !
     ! -- Return
     return
@@ -1480,7 +1477,6 @@ end subroutine read_mvr
   !> @ brief Rewet
   !!
   !! Check if rewetting should propagate from one model to another
-  !!
   !<
   subroutine rewet(this, kiter)
     ! -- modules
@@ -1549,7 +1545,7 @@ subroutine calc_cond_sat(this)
     real(DP) :: csat
     real(DP) :: fawidth
     real(DP), dimension(3) :: vg
-
+    !
     do iexg = 1, this%nexg
       !
       ihc = this%ihc(iexg)
@@ -1617,13 +1613,14 @@ subroutine calc_cond_sat(this)
       ! -- store csat in condsat
       this%condsat(iexg) = csat
     end do
-
+    !
+    ! -- Return
+    return
   end subroutine calc_cond_sat
 
   !> @ brief Calculate the conductance
   !!
   !! Calculate the conductance based on state
-  !!
   !<
   subroutine condcalc(this)
     ! -- modules
@@ -1718,7 +1715,6 @@ end subroutine condcalc
   !> @ brief Allocate scalars
   !!
   !! Allocate scalar variables
-  !!
   !<
   subroutine allocate_scalars(this)
     ! -- modules
@@ -1726,16 +1722,9 @@ subroutine allocate_scalars(this)
     use ConstantsModule, only: DZERO
     ! -- dummy
     class(GwfExchangeType) :: this !<  GwfExchangeType
-    ! -- local
     !
     call this%DisConnExchangeType%allocate_scalars()
     !
-    call mem_allocate(this%iprflow, 'IPRFLOW', this%memoryPath)
-    call mem_allocate(this%ipakcb, 'IPAKCB', this%memoryPath)
-    this%iprpak = 0
-    this%iprflow = 0
-    this%ipakcb = 0
-    !
     call mem_allocate(this%icellavg, 'ICELLAVG', this%memoryPath)
     call mem_allocate(this%ivarcv, 'IVARCV', this%memoryPath)
     call mem_allocate(this%idewatcv, 'IDEWATCV', this%memoryPath)
@@ -1753,21 +1742,19 @@ subroutine allocate_scalars(this)
     this%inobs = 0
     this%satomega = DZERO
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine allocate_scalars
 
   !> @ brief Deallocate
   !!
   !! Deallocate memory associated with this object
-  !!
   !<
   subroutine gwf_gwf_da(this)
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(GwfExchangeType) :: this !<  GwfExchangeType
-    ! -- local
     !
     ! -- objects
     if (this%ingnc > 0) then
@@ -1802,8 +1789,6 @@ subroutine gwf_gwf_da(this)
     !
     ! -- scalars
     deallocate (this%filename)
-    call mem_deallocate(this%iprflow)
-    call mem_deallocate(this%ipakcb)
     !
     call mem_deallocate(this%icellavg)
     call mem_deallocate(this%ivarcv)
@@ -1817,14 +1802,13 @@ subroutine gwf_gwf_da(this)
     ! -- deallocate base
     call this%DisConnExchangeType%disconnex_da()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwf_gwf_da
 
   !> @ brief Allocate arrays
   !!
   !! Allocate arrays
-  !!
   !<
   subroutine allocate_arrays(this)
     ! -- modules
@@ -1892,14 +1876,13 @@ subroutine allocate_arrays(this)
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine allocate_arrays
 
   !> @ brief Define observations
   !!
   !! Define the observations associated with this object
-  !!
   !<
   subroutine gwf_gwf_df_obs(this)
     ! -- dummy
@@ -1912,14 +1895,13 @@ subroutine gwf_gwf_df_obs(this)
     call this%obs%StoreObsType('flow-ja-face', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => gwf_gwf_process_obsID
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwf_gwf_df_obs
 
   !> @ brief Read and prepare observations
   !!
   !! Handle observation exchanges exchange-boundary names.
-  !!
   !<
   subroutine gwf_gwf_rp_obs(this)
     ! -- modules
@@ -1984,7 +1966,7 @@ subroutine gwf_gwf_rp_obs(this)
     !
     ! -- write summary of error messages
     if (count_errors() > 0) then
-      call store_error_unit(this%inobs)
+      call store_error_filename(this%obs%inputFilename)
     end if
     !
     ! -- Return
@@ -1994,19 +1976,18 @@ end subroutine gwf_gwf_rp_obs
   !> @ brief Final processing
   !!
   !! Conduct any final processing
-  !!
   !<
   subroutine gwf_gwf_fp(this)
     ! -- dummy
     class(GwfExchangeType) :: this !<  GwfExchangeType
     !
+    ! -- Return
     return
   end subroutine gwf_gwf_fp
 
   !> @ brief Calculate flow
   !!
   !! Calculate the flow for the specified exchange and node numbers
-  !!
   !<
   function qcalc(this, iexg, n1, n2)
     ! -- return
@@ -2021,7 +2002,7 @@ function qcalc(this, iexg, n1, n2)
     ! -- Calculate flow between nodes in the two models
     qcalc = this%cond(iexg) * (this%gwfmodel2%x(n2) - this%gwfmodel1%x(n1))
     !
-    ! -- return
+    ! -- Return
     return
   end function qcalc
 
@@ -2029,7 +2010,6 @@ end function qcalc
   !!
   !! Return flag indicating whether or not this exchange will cause the
   !! coefficient matrix to be asymmetric.
-  !!
   !<
   function gwf_gwf_get_iasym(this) result(iasym)
     ! -- dummy
@@ -2048,7 +2028,7 @@ function gwf_gwf_get_iasym(this) result(iasym)
       if (this%gnc%iasym /= 0) iasym = 1
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end function gwf_gwf_get_iasym
 
@@ -2056,11 +2036,14 @@ end function gwf_gwf_get_iasym
   !! coefficients for solving @param model
   !<
   function gwf_gwf_connects_model(this, model) result(is_connected)
+    ! -- dummy
     class(GwfExchangeType) :: this !<  GwfExchangeType
     class(BaseModelType), pointer, intent(in) :: model !< the model to which the exchange might hold a connection
+    ! -- return
     logical(LGP) :: is_connected !< true, when connected
-
+    !
     is_connected = .false.
+    !
     ! only connected when model is GwfModelType of course
     select type (model)
     class is (GwfModelType)
@@ -2070,31 +2053,36 @@ function gwf_gwf_connects_model(this, model) result(is_connected)
         is_connected = .true.
       end if
     end select
-
+    !
+    ! -- Return
+    return
   end function gwf_gwf_connects_model
 
   !> @brief Should interface model be used for this exchange
   !<
   function use_interface_model(this) result(use_im)
+    ! -- dummy
     class(GwfExchangeType) :: this !<  GwfExchangeType
+    ! -- return
     logical(LGP) :: use_im !< true when interface model should be used
-
+    !
     use_im = this%DisConnExchangeType%use_interface_model()
     use_im = use_im .or. (this%ixt3d > 0)
-
+    !
+    ! -- Return
+    return
   end function
 
   !> @ brief Save simulated flow observations
   !!
   !! Save the simulated flows for each exchange
-  !!
   !<
   subroutine gwf_gwf_save_simvals(this)
-    ! -- dummy
-    use SimModule, only: store_error, store_error_unit
+    ! -- modules
     use SimVariablesModule, only: errmsg
     use ConstantsModule, only: DZERO
     use ObserveModule, only: ObserveType
+    ! -- dummy
     class(GwfExchangeType), intent(inout) :: this
     ! -- local
     integer(I4B) :: i
@@ -2122,20 +2110,20 @@ subroutine gwf_gwf_save_simvals(this)
             errmsg = 'Unrecognized observation type: '// &
                      trim(obsrv%ObsTypeId)
             call store_error(errmsg)
-            call store_error_unit(this%inobs)
+            call store_error_filename(this%obs%inputFilename)
           end select
           call this%obs%SaveOneSimval(obsrv, v)
         end do
       end do
     end if
     !
+    ! -- Return
     return
   end subroutine gwf_gwf_save_simvals
 
   !> @ brief Obs ID processer
   !!
   !! Process observations for this exchange
-  !!
   !<
   subroutine gwf_gwf_process_obsID(obsrv, dis, inunitobs, iout)
     ! -- modules
@@ -2171,17 +2159,19 @@ subroutine gwf_gwf_process_obsID(obsrv, dis, inunitobs, iout)
       obsrv%intPak1 = NAMEDBOUNDFLAG
     end if
     !
+    ! -- Return
     return
   end subroutine gwf_gwf_process_obsID
 
   !> @ brief Cast polymorphic object as exchange
   !!
   !! Cast polymorphic object as exchange
-  !!
   !<
   function CastAsGwfExchange(obj) result(res)
     implicit none
+    ! -- dummy
     class(*), pointer, intent(inout) :: obj
+    ! -- return
     class(GwfExchangeType), pointer :: res
     !
     res => null()
@@ -2191,19 +2181,21 @@ function CastAsGwfExchange(obj) result(res)
     class is (GwfExchangeType)
       res => obj
     end select
+    !
+    ! -- Return
     return
   end function CastAsGwfExchange
 
   !> @ brief Get exchange from list
   !!
   !! Return an exchange from the list for specified index
-  !!
   !<
   function GetGwfExchangeFromList(list, idx) result(res)
     implicit none
     ! -- dummy
     type(ListType), intent(inout) :: list
     integer(I4B), intent(in) :: idx
+    ! -- return
     class(GwfExchangeType), pointer :: res
     ! -- local
     class(*), pointer :: obj
@@ -2211,6 +2203,7 @@ function GetGwfExchangeFromList(list, idx) result(res)
     obj => list%GetItem(idx)
     res => CastAsGwfExchange(obj)
     !
+    ! -- Return
     return
   end function GetGwfExchangeFromList
 
diff --git a/src/Exchange/GwfGwtExchange.f90 b/src/Exchange/GwfGwtExchange.f90
index 986b84fd990..9313efcce59 100644
--- a/src/Exchange/GwfGwtExchange.f90
+++ b/src/Exchange/GwfGwtExchange.f90
@@ -41,13 +41,9 @@ module GwfGwtExchangeModule
 
 contains
 
+  !> @brief Create a new GWF to GWT exchange object
+  !<
   subroutine gwfgwt_cr(filename, id, m1_id, m2_id)
-! ******************************************************************************
-! gwfgwt_cr -- Create a new GWF to GWT exchange object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SimVariablesModule, only: model_loc_idx
     ! -- dummy
@@ -59,7 +55,6 @@ subroutine gwfgwt_cr(filename, id, m1_id, m2_id)
     class(BaseExchangeType), pointer :: baseexchange => null()
     type(GwfGwtExchangeType), pointer :: exchange => null()
     character(len=20) :: cint
-! ------------------------------------------------------------------------------
     !
     ! -- Create a new exchange and add it to the baseexchangelist container
     allocate (exchange)
@@ -82,25 +77,19 @@ subroutine gwfgwt_cr(filename, id, m1_id, m2_id)
     ! -- set model pointers
     call exchange%set_model_pointers()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwfgwt_cr
 
+  !> @brief Allocate and read
+  !<
   subroutine set_model_pointers(this)
-! ******************************************************************************
-! set_model_pointers -- allocate and read
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfGwtExchangeType) :: this
     ! -- local
     class(BaseModelType), pointer :: mb => null()
     type(GwfModelType), pointer :: gwfmodel => null()
     type(GwtModelType), pointer :: gwtmodel => null()
-! ------------------------------------------------------------------------------
     !
     ! -- set gwfmodel
     gwfmodel => null()
@@ -139,17 +128,13 @@ subroutine set_model_pointers(this)
     !    to look through the flow packages and establish a link to GWF flows
     gwtmodel%fmi%gwfbndlist => gwfmodel%bndlist
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine set_model_pointers
 
+  !> @brief Define GwfGwt Exchange object
+  !<
   subroutine exg_df(this)
-! ******************************************************************************
-! exg_df -- define
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_checkin
     ! -- dummy
@@ -158,8 +143,6 @@ subroutine exg_df(this)
     class(BaseModelType), pointer :: mb => null()
     type(GwfModelType), pointer :: gwfmodel => null()
     type(GwtModelType), pointer :: gwtmodel => null()
-! ------------------------------------------------------------------------------
-    !
     !
     ! -- set gwfmodel
     mb => GetBaseModelFromList(basemodellist, this%m1_idx)
@@ -198,17 +181,13 @@ subroutine exg_df(this)
       gwfmodel%npf%icalcspdis = 1
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine exg_df
 
+  !> @brief Allocate and read
+  !<
   subroutine exg_ar(this)
-! ******************************************************************************
-! exg_ar --
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_checkin
     ! -- dummy
@@ -224,7 +203,6 @@ subroutine exg_ar(this)
       &  GWF Model has ', i0, ' user nodes and ', i0, ' reduced nodes.&
       &  GWT Model has ', i0, ' user nodes and ', i0, ' reduced nodes.&
       &  Ensure discretization packages, including IDOMAIN, are identical.')"
-! ------------------------------------------------------------------------------
     !
     ! -- set gwfmodel
     mb => GetBaseModelFromList(basemodellist, this%m1_idx)
@@ -301,20 +279,22 @@ subroutine exg_ar(this)
     ! -- connect Connections
     call this%gwfconn2gwtconn(gwfmodel, gwtmodel)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine exg_ar
 
   !> @brief Link GWT connections to GWF connections or exchanges
   !<
   subroutine gwfconn2gwtconn(this, gwfModel, gwtModel)
+    ! -- modules
     use SimModule, only: store_error
     use SimVariablesModule, only: iout
     use MemoryManagerModule, only: mem_checkin
+    ! -- dummy
     class(GwfGwtExchangeType) :: this !< this exchange
     type(GwfModelType), pointer :: gwfModel !< the flow model
     type(GwtModelType), pointer :: gwtModel !< the transport model
-    ! local
+    ! -- local
     class(SpatialModelConnectionType), pointer :: conn => null()
     class(*), pointer :: objPtr => null()
     class(GwtGwtConnectionType), pointer :: gwtConn => null()
@@ -323,27 +303,27 @@ subroutine gwfconn2gwtconn(this, gwfModel, gwtModel)
     integer(I4B) :: ic1, ic2, iex
     integer(I4B) :: gwfConnIdx, gwfExIdx
     logical(LGP) :: areEqual
-
+    !
     ! loop over all connections
     gwtloop: do ic1 = 1, baseconnectionlist%Count()
-
+      !
       conn => get_smc_from_list(baseconnectionlist, ic1)
       if (.not. associated(conn%owner, gwtModel)) cycle gwtloop
-
+      !
       ! start with a GWT conn.
       objPtr => conn
       gwtConn => CastAsGwtGwtConnection(objPtr)
       gwfConnIdx = -1
       gwfExIdx = -1
-
+      !
       ! find matching GWF conn. in same list
       gwfloop: do ic2 = 1, baseconnectionlist%Count()
         conn => get_smc_from_list(baseconnectionlist, ic2)
-
+        !
         if (associated(conn%owner, gwfModel)) then
           objPtr => conn
           gwfConn => CastAsGwfGwfConnection(objPtr)
-
+          !
           ! for now, connecting the same nodes nrs will be
           ! sufficient evidence of equality
           areEqual = all(gwfConn%prim_exchange%nodem1 == &
@@ -363,24 +343,28 @@ subroutine gwfconn2gwtconn(this, gwfModel, gwtModel)
           end if
         end if
       end do gwfloop
-
+      !
       ! fallback option: coupling to old gwfgwf exchange,
       ! (this will go obsolete at some point)
       if (gwfConnIdx == -1) then
         gwfloopexg: do iex = 1, baseexchangelist%Count()
           gwfEx => GetGwfExchangeFromList(baseexchangelist, iex)
-
+          !
           ! -- There is no guarantee that iex is a gwfExg, in which case
           !    it will return as null.  cycle if so.
           if (.not. associated(gwfEx)) cycle gwfloopexg
-
+          !
           if (associated(gwfEx%model1, gwfModel) .or. &
               associated(gwfEx%model2, gwfModel)) then
-            ! again, connecting the same nodes nrs will be
+
+            ! check exchanges have same node counts
+            areEqual = size(gwfEx%nodem1) == size(gwtConn%prim_exchange%nodem1)
+            ! then, connecting the same nodes nrs will be
             ! sufficient evidence of equality
-            areEqual = all(gwfEx%nodem1 == gwtConn%prim_exchange%nodem1)
-            areEqual = areEqual .and. &
-                       all(gwfEx%nodem2 == gwtConn%prim_exchange%nodem2)
+            if (areEqual) &
+              areEqual = all(gwfEx%nodem1 == gwtConn%prim_exchange%nodem1)
+            if (areEqual) &
+              areEqual = all(gwfEx%nodem2 == gwtConn%prim_exchange%nodem2)
             if (areEqual) then
               ! link exchange to connection
               write (iout, '(/6a)') 'Linking exchange ', &
@@ -388,32 +372,32 @@ subroutine gwfconn2gwtconn(this, gwfModel, gwtModel)
                 ' to ', trim(gwfEx%name), ' for GWT model ', &
                 trim(gwtModel%name)
               gwfExIdx = iex
-              if (gwtConn%exchangeIsOwned) then
+              if (gwtConn%owns_exchange) then
                 gwtConn%gwtExchange%gwfsimvals => gwfEx%simvals
                 call mem_checkin(gwtConn%gwtExchange%gwfsimvals, &
                                  'GWFSIMVALS', gwtConn%gwtExchange%memoryPath, &
                                  'SIMVALS', gwfEx%memoryPath)
               end if
-
+              !
               !cdl link up mvt to mvr
               if (gwfEx%inmvr > 0) then
-                if (gwtConn%exchangeIsOwned) then
+                if (gwtConn%owns_exchange) then
                   !cdl todo: check and make sure gwtEx has mvt active
                   call gwtConn%gwtExchange%mvt%set_pointer_mvrbudobj( &
                     gwfEx%mvr%budobj)
                 end if
               end if
-
+              !
               if (associated(gwfEx%model2, gwfModel)) gwtConn%exgflowSign = -1
               gwtConn%gwtInterfaceModel%fmi%flows_from_file = .false.
-
+              !
               exit gwfloopexg
             end if
           end if
-
+          !
         end do gwfloopexg
       end if
-
+      !
       if (gwfConnIdx == -1 .and. gwfExIdx == -1) then
         ! none found, report
         write (errmsg, '(/6a)') 'Missing GWF-GWF exchange when connecting GWT'// &
@@ -422,103 +406,93 @@ subroutine gwfconn2gwtconn(this, gwfModel, gwtModel)
           trim(gwfModel%name)
         call store_error(errmsg, terminate=.true.)
       end if
-
+      !
     end do gwtloop
-
+    !
+    ! -- Return
+    return
   end subroutine gwfconn2gwtconn
 
   !> @brief Links a GWT connection to its GWF counterpart
   !<
   subroutine link_connections(this, gwtConn, gwfConn)
+    ! -- modules
     use MemoryManagerModule, only: mem_checkin
+    ! -- dummy
     class(GwfGwtExchangeType) :: this !< this exchange
     class(GwtGwtConnectionType), pointer :: gwtConn !< GWT connection
     class(GwfGwfConnectionType), pointer :: gwfConn !< GWF connection
-
+    !
     !gwtConn%exgflowja => gwfConn%exgflowja
-    if (gwtConn%exchangeIsOwned) then
+    if (gwtConn%owns_exchange) then
       gwtConn%gwtExchange%gwfsimvals => gwfConn%gwfExchange%simvals
       call mem_checkin(gwtConn%gwtExchange%gwfsimvals, &
                        'GWFSIMVALS', gwtConn%gwtExchange%memoryPath, &
                        'SIMVALS', gwfConn%gwfExchange%memoryPath)
     end if
-
+    !
     !cdl link up mvt to mvr
     if (gwfConn%gwfExchange%inmvr > 0) then
-      if (gwtConn%exchangeIsOwned) then
+      if (gwtConn%owns_exchange) then
         !cdl todo: check and make sure gwtEx has mvt active
         call gwtConn%gwtExchange%mvt%set_pointer_mvrbudobj( &
           gwfConn%gwfExchange%mvr%budobj)
       end if
     end if
-
+    !
     if (associated(gwfConn%gwfExchange%model2, gwfConn%owner)) then
       gwtConn%exgflowSign = -1
     end if
-
+    !
     ! fmi flows are not read from file
     gwtConn%gwtInterfaceModel%fmi%flows_from_file = .false.
-
+    !
     ! set concentration pointer for buoyancy
-    call gwfConn%gwfInterfaceModel%buy%set_concentration_pointer( &
-      gwtConn%gwtModel%name, &
-      gwtConn%conc, &
-      gwtConn%icbound)
-
+    ! call gwfConn%gwfInterfaceModel%buy%set_concentration_pointer( &
+    !   gwtConn%gwtModel%name, &
+    !   gwtConn%conc, &
+    !   gwtConn%icbound)
+    !
+    ! -- Return
+    return
   end subroutine link_connections
 
+  !> @brief Deallocate memory
+  !<
   subroutine exg_da(this)
-! ******************************************************************************
-! allocate_scalars
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(GwfGwtExchangeType) :: this
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     call mem_deallocate(this%m1_idx)
     call mem_deallocate(this%m2_idx)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine exg_da
 
+  !> @brief Allocate package scalars
+  !<
   subroutine allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwfGwtExchangeType) :: this
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     call mem_allocate(this%m1_idx, 'M1ID', this%memoryPath)
     call mem_allocate(this%m2_idx, 'M2ID', this%memoryPath)
     this%m1_idx = 0
     this%m2_idx = 0
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine allocate_scalars
 
+  !> @brief Call routines in FMI that will set pointers to the necessary flow
+  !! data
+  !<
   subroutine gwfbnd2gwtfmi(this)
-! ******************************************************************************
-! gwfbnd2gwtfmi
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfGwtExchangeType) :: this
     ! -- local
@@ -527,7 +501,6 @@ subroutine gwfbnd2gwtfmi(this)
     type(GwfModelType), pointer :: gwfmodel => null()
     type(GwtModelType), pointer :: gwtmodel => null()
     class(BndType), pointer :: packobj => null()
-! ------------------------------------------------------------------------------
     !
     ! -- set gwfmodel
     mb => GetBaseModelFromList(basemodellist, this%m1_idx)
@@ -551,7 +524,7 @@ subroutine gwfbnd2gwtfmi(this)
       packobj => GetBndFromList(gwfmodel%bndlist, ip)
       call gwtmodel%fmi%gwfpackages(iterm)%set_pointers( &
         'SIMVALS', &
-        packobj%memoryPath)
+        packobj%memoryPath, packobj%input_mempath)
       iterm = iterm + 1
       !
       ! -- If a mover is active for this package, then establish a separate
@@ -561,12 +534,12 @@ subroutine gwfbnd2gwtfmi(this)
       if (imover /= 0) then
         call gwtmodel%fmi%gwfpackages(iterm)%set_pointers( &
           'SIMTOMVR', &
-          packobj%memoryPath)
+          packobj%memoryPath, packobj%input_mempath)
         iterm = iterm + 1
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwfbnd2gwtfmi
 
diff --git a/src/Exchange/GwtGwtExchange.f90 b/src/Exchange/GwtGwtExchange.f90
index faf7d1345ba..c4833aeef7d 100644
--- a/src/Exchange/GwtGwtExchange.f90
+++ b/src/Exchange/GwtGwtExchange.f90
@@ -11,7 +11,8 @@ module GwtGwtExchangeModule
 
   use KindModule, only: DP, I4B, LGP
   use SimVariablesModule, only: errmsg, model_loc_idx
-  use SimModule, only: store_error
+  use SimModule, only: store_error, store_error_filename, &
+                       count_errors, ustop
   use BaseModelModule, only: BaseModelType, GetBaseModelFromList
   use BaseExchangeModule, only: BaseExchangeType, AddBaseExchangeToList
   use ConstantsModule, only: LENBOUNDNAME, NAMEDBOUNDFLAG, LINELENGTH, &
@@ -22,13 +23,10 @@ module GwtGwtExchangeModule
   use VirtualModelModule, only: get_virtual_model
   use DisConnExchangeModule, only: DisConnExchangeType
   use GwtModule, only: GwtModelType
-  use GwtMvtModule, only: GwtMvtType
+  use TspMvtModule, only: TspMvtType
+  use VirtualModelModule, only: VirtualModelType
   use ObserveModule, only: ObserveType
   use ObsModule, only: ObsType
-  use SimModule, only: count_errors, store_error, &
-                       store_error_unit, ustop
-  use SimVariablesModule, only: errmsg
-  use BlockParserModule, only: BlockParserType
   use TableModule, only: TableType, table_cr
   use MatrixBaseModule
 
@@ -44,7 +42,6 @@ module GwtGwtExchangeModule
   !!
   !! This derived type contains information and methods for
   !! connecting two GWT models.
-  !!
   !<
   type, extends(DisConnExchangeType) :: GwtExchangeType
     !
@@ -54,19 +51,17 @@ module GwtGwtExchangeModule
     real(DP), dimension(:), pointer, contiguous :: gwfsimvals => null() !< simulated gwf flow rate for each exchange
     !
     ! -- pointers to gwt models
-    type(GwtModelType), pointer :: gwtmodel1 => null() !< pointer to GWT Model 1
-    type(GwtModelType), pointer :: gwtmodel2 => null() !< pointer to GWT Model 2
+    class(GwtModelType), pointer :: gwtmodel1 => null() !< pointer to GWT Model 1
+    class(GwtModelType), pointer :: gwtmodel2 => null() !< pointer to GWT Model 2
     !
     ! -- GWT specific option block:
     integer(I4B), pointer :: inewton => null() !< unneeded newton flag allows for mvt to be used here
-    integer(I4B), pointer :: iprflow => null() !< print flag for cell by cell flows
-    integer(I4B), pointer :: ipakcb => null() !< save flag for cell by cell flows
     integer(I4B), pointer :: iAdvScheme !< the advection scheme at the interface:
                                                                                  !! 0 = upstream, 1 = central, 2 = TVD
     !
     ! -- Mover transport package
     integer(I4B), pointer :: inmvt => null() !< unit number for mover transport (0 if off)
-    type(GwtMvtType), pointer :: mvt => null() !< water mover object
+    type(TspMvtType), pointer :: mvt => null() !< water mover object
     !
     ! -- Observation package
     integer(I4B), pointer :: inobs => null() !< unit number for GWT-GWT observations
@@ -95,10 +90,10 @@ module GwtGwtExchangeModule
     procedure :: use_interface_model
     procedure :: allocate_scalars
     procedure :: allocate_arrays
-    procedure :: read_options
-    procedure :: parse_option
+    procedure :: source_options
     procedure :: read_mvt
     procedure :: gwt_gwt_bdsav
+    procedure, private :: gwt_gwt_bdsav_model
     procedure, private :: gwt_gwt_df_obs
     procedure, private :: gwt_gwt_rp_obs
     procedure, public :: gwt_gwt_save_simvals
@@ -110,11 +105,9 @@ module GwtGwtExchangeModule
   !> @ brief Create GWT GWT exchange
   !!
   !! Create a new GWT to GWT exchange object.
-  !!
   !<
-  subroutine gwtexchange_create(filename, name, id, m1_id, m2_id)
+  subroutine gwtexchange_create(filename, name, id, m1_id, m2_id, input_mempath)
     ! -- modules
-    use ConstantsModule, only: LINELENGTH
     use BaseModelModule, only: BaseModelType
     use ListsModule, only: baseexchangelist
     use ObsModule, only: obs_cr
@@ -125,6 +118,7 @@ subroutine gwtexchange_create(filename, name, id, m1_id, m2_id)
     character(len=*) :: name !< the exchange name
     integer(I4B), intent(in) :: m1_id !< id for model 1
     integer(I4B), intent(in) :: m2_id !< id for model 2
+    character(len=*), intent(in) :: input_mempath
     ! -- local
     type(GwtExchangeType), pointer :: exchange
     class(BaseModelType), pointer :: mb
@@ -140,6 +134,7 @@ subroutine gwtexchange_create(filename, name, id, m1_id, m2_id)
     exchange%id = id
     exchange%name = name
     exchange%memoryPath = create_mem_path(exchange%name)
+    exchange%input_mempath = input_mempath
     !
     ! -- allocate scalars and set defaults
     call exchange%allocate_scalars()
@@ -151,21 +146,25 @@ subroutine gwtexchange_create(filename, name, id, m1_id, m2_id)
     ! -- set gwtmodel1
     m1_index = model_loc_idx(m1_id)
     mb => GetBaseModelFromList(basemodellist, m1_index)
-    select type (mb)
-    type is (GwtModelType)
-      exchange%model1 => mb
-      exchange%gwtmodel1 => mb
-    end select
+    if (m1_index > 0) then
+      select type (mb)
+      type is (GwtModelType)
+        exchange%model1 => mb
+        exchange%gwtmodel1 => mb
+      end select
+    end if
     exchange%v_model1 => get_virtual_model(m1_id)
     !
     ! -- set gwtmodel2
     m2_index = model_loc_idx(m2_id)
-    mb => GetBaseModelFromList(basemodellist, m2_index)
-    select type (mb)
-    type is (GwtModelType)
-      exchange%model2 => mb
-      exchange%gwtmodel2 => mb
-    end select
+    if (m2_index > 0) then
+      mb => GetBaseModelFromList(basemodellist, m2_index)
+      select type (mb)
+      type is (GwtModelType)
+        exchange%model2 => mb
+        exchange%gwtmodel2 => mb
+      end select
+    end if
     exchange%v_model2 => get_virtual_model(m2_id)
     !
     ! -- Verify that gwt model1 is of the correct type
@@ -176,7 +175,7 @@ subroutine gwtexchange_create(filename, name, id, m1_id, m2_id)
       call store_error(errmsg, terminate=.true.)
     end if
     !
-    ! -- Verify that gwf model2 is of the correct type
+    ! -- Verify that gwt model2 is of the correct type
     if (.not. associated(exchange%gwtmodel2) .and. m2_index > 0) then
       write (errmsg, '(3a)') 'Problem with GWT-GWT exchange ', &
         trim(exchange%name), &
@@ -187,14 +186,13 @@ subroutine gwtexchange_create(filename, name, id, m1_id, m2_id)
     ! -- Create the obs package
     call obs_cr(exchange%obs, exchange%inobs)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwtexchange_create
 
   !> @ brief Define GWT GWT exchange
   !!
   !! Define GWT to GWT exchange object.
-  !!
   !<
   subroutine gwt_gwt_df(this)
     ! -- modules
@@ -204,35 +202,31 @@ subroutine gwt_gwt_df(this)
     ! -- dummy
     class(GwtExchangeType) :: this !<  GwtExchangeType
     ! -- local
-    integer(I4B) :: inunit
     !
-    ! -- open the file
-    inunit = getunit()
+    ! -- log the exchange
     write (iout, '(/a,a)') ' Creating exchange: ', this%name
-    call openfile(inunit, iout, this%filename, 'GWT-GWT')
-    !
-    call this%parser%Initialize(inunit, iout)
     !
     ! -- Ensure models are in same solution
-    if (this%gwtmodel1%idsoln /= this%gwtmodel2%idsoln) then
+    if (this%v_model1%idsoln%get() /= this%v_model2%idsoln%get()) then
       call store_error('Two models are connected in a GWT '// &
                        'exchange but they are in different solutions. '// &
                        'GWT models must be in same solution: '// &
-                       trim(this%gwtmodel1%name)//' '//trim(this%gwtmodel2%name))
-      call this%parser%StoreErrorUnit()
+                       trim(this%v_model1%name)//' '// &
+                       trim(this%v_model2%name))
+      call store_error_filename(this%filename)
     end if
     !
-    ! -- read options
-    call this%read_options(iout)
+    ! -- source options
+    call this%source_options(iout)
     !
-    ! -- read dimensions
-    call this%read_dimensions(iout)
+    ! -- source dimensions
+    call this%source_dimensions(iout)
     !
     ! -- allocate arrays
     call this%allocate_arrays()
     !
-    ! -- read exchange data
-    call this%read_data(iout)
+    ! -- source exchange data
+    call this%source_data(iout)
     !
     ! -- Read mover information
     if (this%inmvt > 0) then
@@ -240,26 +234,25 @@ subroutine gwt_gwt_df(this)
       call this%mvt%mvt_df(this%gwtmodel1%dis)
     end if
     !
-    ! -- close the file
-    close (inunit)
-    !
     ! -- Store obs
     call this%gwt_gwt_df_obs()
-    call this%obs%obs_df(iout, this%name, 'GWT-GWT', this%gwtmodel1%dis)
+    if (associated(this%gwtmodel1)) then
+      call this%obs%obs_df(iout, this%name, 'GWT-GWT', this%gwtmodel1%dis)
+    end if
     !
     ! -- validate
     call this%validate_exchange()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwt_gwt_df
 
   !> @brief validate exchange data after reading
   !<
   subroutine validate_exchange(this)
+    ! -- dummy
     class(GwtExchangeType) :: this !<  GwtExchangeType
-    ! local
-
+    !
     ! Ensure gwfmodel names were entered
     if (this%gwfmodelname1 == '') then
       write (errmsg, '(3a)') 'GWT-GWT exchange ', trim(this%name), &
@@ -273,9 +266,9 @@ subroutine validate_exchange(this)
                             &OPTIONS block.'
       call store_error(errmsg)
     end if
-
+    !
     ! Periodic boundary condition in exchange don't allow XT3D (=interface model)
-    if (associated(this%model1, this%model2)) then
+    if (this%v_model1 == this%v_model2) then
       if (this%ixt3d > 0) then
         write (errmsg, '(3a)') 'GWT-GWT exchange ', trim(this%name), &
           ' is a periodic boundary condition which cannot'// &
@@ -283,43 +276,44 @@ subroutine validate_exchange(this)
         call store_error(errmsg)
       end if
     end if
-
+    !
     ! Check to see if dispersion is on in either model1 or model2.
     ! If so, then ANGLDEGX must be provided as an auxiliary variable for this
     ! GWT-GWT exchange (this%ianglex > 0).
-    if (this%gwtmodel1%indsp /= 0 .or. this%gwtmodel2%indsp /= 0) then
-      if (this%ianglex == 0) then
-        write (errmsg, '(3a)') 'GWT-GWT exchange ', trim(this%name), &
-          ' requires that ANGLDEGX be specified as an'// &
-          ' auxiliary variable because dispersion was '// &
-          'specified in one or both transport models.'
-        call store_error(errmsg)
+    if (associated(this%gwtmodel1) .and. associated(this%gwtmodel2)) then
+      if (this%gwtmodel1%indsp /= 0 .or. this%gwtmodel2%indsp /= 0) then
+        if (this%ianglex == 0) then
+          write (errmsg, '(3a)') 'GWT-GWT exchange ', trim(this%name), &
+            ' requires that ANGLDEGX be specified as an'// &
+            ' auxiliary variable because dispersion was '// &
+            'specified in one or both transport models.'
+          call store_error(errmsg)
+        end if
       end if
     end if
-
+    !
     if (this%ixt3d > 0 .and. this%ianglex == 0) then
       write (errmsg, '(3a)') 'GWT-GWT exchange ', trim(this%name), &
         ' requires that ANGLDEGX be specified as an'// &
         ' auxiliary variable because XT3D is enabled'
       call store_error(errmsg)
     end if
-
+    !
     if (count_errors() > 0) then
       call ustop()
     end if
-
+    !
+    ! -- Return
+    return
   end subroutine validate_exchange
 
   !> @ brief Allocate and read
   !!
   !! Allocated and read and calculate saturated conductance
-  !!
   !<
   subroutine gwt_gwt_ar(this)
-    ! -- modules
     ! -- dummy
     class(GwtExchangeType) :: this !<  GwtExchangeType
-    ! -- local
     !
     ! -- If mover is active, then call ar routine
     if (this%inmvt > 0) call this%mvt%mvt_ar()
@@ -334,7 +328,6 @@ end subroutine gwt_gwt_ar
   !> @ brief Read and prepare
   !!
   !! Read new data for mover and obs
-  !!
   !<
   subroutine gwt_gwt_rp(this)
     ! -- modules
@@ -358,13 +351,10 @@ end subroutine gwt_gwt_rp
   !> @ brief Advance
   !!
   !! Advance mover and obs
-  !!
   !<
   subroutine gwt_gwt_ad(this)
-    ! -- modules
     ! -- dummy
     class(GwtExchangeType) :: this !<  GwtExchangeType
-    ! -- local
     !
     ! -- Advance mover
     !if(this%inmvt > 0) call this%mvt%mvt_ad()
@@ -379,17 +369,14 @@ end subroutine gwt_gwt_ad
   !> @ brief Fill coefficients
   !!
   !! Calculate conductance and fill coefficient matrix
-  !!
   !<
   subroutine gwt_gwt_fc(this, kiter, matrix_sln, rhs_sln, inwtflag)
-    ! -- modules
     ! -- dummy
     class(GwtExchangeType) :: this !<  GwtExchangeType
     integer(I4B), intent(in) :: kiter
     class(MatrixBaseType), pointer :: matrix_sln
     real(DP), dimension(:), intent(inout) :: rhs_sln
     integer(I4B), optional, intent(in) :: inwtflag
-    ! -- local
     !
     ! -- Call mvt fc routine
     if (this%inmvt > 0) call this%mvt%mvt_fc(this%gwtmodel1%x, this%gwtmodel2%x)
@@ -401,7 +388,6 @@ end subroutine gwt_gwt_fc
   !> @ brief Budget
   !!
   !! Accumulate budget terms
-  !!
   !<
   subroutine gwt_gwt_bd(this, icnvg, isuppress_output, isolnid)
     ! -- modules
@@ -416,7 +402,6 @@ subroutine gwt_gwt_bd(this, icnvg, isuppress_output, isolnid)
     character(len=LENBUDTXT), dimension(1) :: budtxt
     real(DP), dimension(2, 1) :: budterm
     real(DP) :: ratin, ratout
-    ! -- formats
     !
     ! -- initialize
     budtxt(1) = '    FLOW-JA-FACE'
@@ -425,70 +410,114 @@ subroutine gwt_gwt_bd(this, icnvg, isuppress_output, isolnid)
     call rate_accumulator(this%simvals, ratin, ratout)
     !
     ! -- Add the budget terms to model 1
-    budterm(1, 1) = ratin
-    budterm(2, 1) = ratout
-    call this%gwtmodel1%model_bdentry(budterm, budtxt, this%name)
+    if (associated(this%gwtmodel1)) then
+      budterm(1, 1) = ratin
+      budterm(2, 1) = ratout
+      call this%gwtmodel1%model_bdentry(budterm, budtxt, this%name)
+    end if
     !
     ! -- Add the budget terms to model 2
-    budterm(1, 1) = ratout
-    budterm(2, 1) = ratin
-    call this%gwtmodel2%model_bdentry(budterm, budtxt, this%name)
+    if (associated(this%gwtmodel2)) then
+      budterm(1, 1) = ratout
+      budterm(2, 1) = ratin
+      call this%gwtmodel2%model_bdentry(budterm, budtxt, this%name)
+    end if
     !
     ! -- Call mvt bd routine
     if (this%inmvt > 0) call this%mvt%mvt_bd(this%gwtmodel1%x, this%gwtmodel2%x)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwt_gwt_bd
 
   !> @ brief Budget save
   !!
   !! Output individual flows to listing file and binary budget files
-  !!
   !<
   subroutine gwt_gwt_bdsav(this)
+    ! -- dummy
+    class(GwtExchangeType) :: this !<  GwtExchangeType
+    ! -- local
+    integer(I4B) :: icbcfl, ibudfl
+    !
+    ! -- budget for model1
+    if (associated(this%gwtmodel1)) then
+      call this%gwt_gwt_bdsav_model(this%gwtmodel1)
+    end if
+    !
+    ! -- budget for model2
+    if (associated(this%gwtmodel2)) then
+      call this%gwt_gwt_bdsav_model(this%gwtmodel2)
+    end if
+    !
+    ! -- Set icbcfl, ibudfl to zero so that flows will be printed and
+    !    saved, if the options were set in the MVT package
+    icbcfl = 1
+    ibudfl = 1
+    !
+    ! -- Call mvt bd routine
+    !cdl todo: if(this%inmvt > 0) call this%mvt%mvt_bdsav(icbcfl, ibudfl, isuppress_output)
+    !
+    ! -- Calculate and write simulated values for observations
+    if (this%inobs /= 0) then
+      call this%gwt_gwt_save_simvals()
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine gwt_gwt_bdsav
+
+  !> @ brief Budget save
+  !!
+  !! Output individual flows to listing file and binary budget files
+  !<
+  subroutine gwt_gwt_bdsav_model(this, model)
     ! -- modules
     use ConstantsModule, only: DZERO, LENBUDTXT, LENPACKAGENAME
     use TdisModule, only: kstp, kper
     ! -- dummy
     class(GwtExchangeType) :: this !<  GwtExchangeType
+    class(GwtModelType), pointer :: model
     ! -- local
     character(len=LENBOUNDNAME) :: bname
-    character(len=LENPACKAGENAME + 4) :: packname1
-    character(len=LENPACKAGENAME + 4) :: packname2
+    character(len=LENPACKAGENAME + 4) :: packname
     character(len=LENBUDTXT), dimension(1) :: budtxt
+    type(TableType), pointer :: output_tab
+    class(VirtualModelType), pointer :: nbr_model
     character(len=20) :: nodestr
     integer(I4B) :: ntabrows
     integer(I4B) :: nodeu
     integer(I4B) :: i, n1, n2, n1u, n2u
-    integer(I4B) :: ibinun1, ibinun2
-    integer(I4B) :: icbcfl, ibudfl
+    integer(I4B) :: ibinun
     real(DP) :: ratin, ratout, rrate
+    logical(LGP) :: is_for_model1
     integer(I4B) :: isuppress_output
-    ! -- formats
     !
     ! -- initialize local variables
     isuppress_output = 0
     budtxt(1) = '    FLOW-JA-FACE'
-    packname1 = 'EXG '//this%name
-    packname1 = adjustr(packname1)
-    packname2 = 'EXG '//this%name
-    packname2 = adjustr(packname2)
+    packname = 'EXG '//this%name
+    packname = adjustr(packname)
+    if (associated(model, this%gwtmodel1)) then
+      output_tab => this%outputtab1
+      nbr_model => this%v_model2
+      is_for_model1 = .true.
+    else
+      output_tab => this%outputtab2
+      nbr_model => this%v_model1
+      is_for_model1 = .false.
+    end if
     !
     ! -- update output tables
     if (this%iprflow /= 0) then
       !
       ! -- update titles
-      if (this%gwtmodel1%oc%oc_save('BUDGET')) then
-        call this%outputtab1%set_title(packname1)
-      end if
-      if (this%gwtmodel2%oc%oc_save('BUDGET')) then
-        call this%outputtab2%set_title(packname2)
+      if (model%oc%oc_save('BUDGET')) then
+        call output_tab%set_title(packname)
       end if
       !
       ! -- set table kstp and kper
-      call this%outputtab1%set_kstpkper(kstp, kper)
-      call this%outputtab2%set_kstpkper(kstp, kper)
+      call output_tab%set_kstpkper(kstp, kper)
       !
       ! -- update maxbound of tables
       ntabrows = 0
@@ -497,14 +526,13 @@ subroutine gwt_gwt_bdsav(this)
         n2 = this%nodem2(i)
         !
         ! -- If both cells are active then calculate flow rate
-        if (this%gwtmodel1%ibound(n1) /= 0 .and. &
-            this%gwtmodel2%ibound(n2) /= 0) then
+        if (this%v_model1%ibound%get(n1) /= 0 .and. &
+            this%v_model2%ibound%get(n2) /= 0) then
           ntabrows = ntabrows + 1
         end if
       end do
       if (ntabrows > 0) then
-        call this%outputtab1%set_maxbound(ntabrows)
-        call this%outputtab2%set_maxbound(ntabrows)
+        call output_tab%set_maxbound(ntabrows)
       end if
     end if
     !
@@ -512,28 +540,28 @@ subroutine gwt_gwt_bdsav(this)
     !
     ! -- Set binary unit numbers for saving flows
     if (this%ipakcb /= 0) then
-      ibinun1 = this%gwtmodel1%oc%oc_save_unit('BUDGET')
+      ibinun = model%oc%oc_save_unit('BUDGET')
     else
-      ibinun1 = 0
+      ibinun = 0
     end if
     !
     ! -- If save budget flag is zero for this stress period, then
     !    shut off saving
-    if (.not. this%gwtmodel1%oc%oc_save('BUDGET')) ibinun1 = 0
+    if (.not. model%oc%oc_save('BUDGET')) ibinun = 0
     if (isuppress_output /= 0) then
-      ibinun1 = 0
+      ibinun = 0
     end if
     !
     ! -- If cell-by-cell flows will be saved as a list, write header.
-    if (ibinun1 /= 0) then
-      call this%gwtmodel1%dis%record_srcdst_list_header(budtxt(1), &
-                                                        this%gwtmodel1%name, &
-                                                        this%name, &
-                                                        this%gwtmodel2%name, &
-                                                        this%name, &
-                                                        this%naux, this%auxname, &
-                                                        ibinun1, this%nexg, &
-                                                        this%gwtmodel1%iout)
+    if (ibinun /= 0) then
+      call model%dis%record_srcdst_list_header(budtxt(1), &
+                                               model%name, &
+                                               this%name, &
+                                               nbr_model%name, &
+                                               this%name, &
+                                               this%naux, this%auxname, &
+                                               ibinun, this%nexg, &
+                                               model%iout)
     end if
     !
     ! Initialize accumulators
@@ -556,19 +584,26 @@ subroutine gwt_gwt_bdsav(this)
       n2 = this%nodem2(i)
       !
       ! -- If both cells are active then calculate flow rate
-      if (this%gwtmodel1%ibound(n1) /= 0 .and. &
-          this%gwtmodel2%ibound(n2) /= 0) then
+      if (this%v_model1%ibound%get(n1) /= 0 .and. &
+          this%v_model2%ibound%get(n2) /= 0) then
         rrate = this%simvals(i)
         !
         ! -- Print the individual rates to model list files if requested
         if (this%iprflow /= 0) then
-          if (this%gwtmodel1%oc%oc_save('BUDGET')) then
+          if (model%oc%oc_save('BUDGET')) then
             !
             ! -- set nodestr and write outputtab table
-            nodeu = this%gwtmodel1%dis%get_nodeuser(n1)
-            call this%gwtmodel1%dis%nodeu_to_string(nodeu, nodestr)
-            call this%outputtab1%print_list_entry(i, trim(adjustl(nodestr)), &
-                                                  rrate, bname)
+            if (is_for_model1) then
+              nodeu = model%dis%get_nodeuser(n1)
+              call model%dis%nodeu_to_string(nodeu, nodestr)
+              call output_tab%print_list_entry(i, trim(adjustl(nodestr)), &
+                                               rrate, bname)
+            else
+              nodeu = model%dis%get_nodeuser(n2)
+              call model%dis%nodeu_to_string(nodeu, nodestr)
+              call output_tab%print_list_entry(i, trim(adjustl(nodestr)), &
+                                               -rrate, bname)
+            end if
           end if
         end if
         if (rrate < DZERO) then
@@ -579,121 +614,34 @@ subroutine gwt_gwt_bdsav(this)
       end if
       !
       ! -- If saving cell-by-cell flows in list, write flow
-      n1u = this%gwtmodel1%dis%get_nodeuser(n1)
-      n2u = this%gwtmodel2%dis%get_nodeuser(n2)
-      if (ibinun1 /= 0) &
-        call this%gwtmodel1%dis%record_mf6_list_entry( &
-        ibinun1, n1u, n2u, rrate, this%naux, this%auxvar(:, i), &
-        .false., .false.)
-      !
-    end do
-    !
-    ! -- Print and write budget terms for model 2
-    !
-    ! -- Set binary unit numbers for saving flows
-    if (this%ipakcb /= 0) then
-      ibinun2 = this%gwtmodel2%oc%oc_save_unit('BUDGET')
-    else
-      ibinun2 = 0
-    end if
-    !
-    ! -- If save budget flag is zero for this stress period, then
-    !    shut off saving
-    if (.not. this%gwtmodel2%oc%oc_save('BUDGET')) ibinun2 = 0
-    if (isuppress_output /= 0) then
-      ibinun2 = 0
-    end if
-    !
-    ! -- If cell-by-cell flows will be saved as a list, write header.
-    if (ibinun2 /= 0) then
-      call this%gwtmodel2%dis%record_srcdst_list_header(budtxt(1), &
-                                                        this%gwtmodel2%name, &
-                                                        this%name, &
-                                                        this%gwtmodel1%name, &
-                                                        this%name, &
-                                                        this%naux, this%auxname, &
-                                                        ibinun2, this%nexg, &
-                                                        this%gwtmodel2%iout)
-    end if
-    !
-    ! Initialize accumulators
-    ratin = DZERO
-    ratout = DZERO
-    !
-    ! -- Loop through all exchanges
-    do i = 1, this%nexg
-      !
-      ! -- Assign boundary name
-      if (this%inamedbound > 0) then
-        bname = this%boundname(i)
-      else
-        bname = ''
-      end if
-      !
-      ! -- Calculate the flow rate between n1 and n2
-      rrate = DZERO
-      n1 = this%nodem1(i)
-      n2 = this%nodem2(i)
-      !
-      ! -- If both cells are active then calculate flow rate
-      if (this%gwtmodel1%ibound(n1) /= 0 .and. &
-          this%gwtmodel2%ibound(n2) /= 0) then
-        rrate = this%simvals(i)
-        !
-        ! -- Print the individual rates to model list files if requested
-        if (this%iprflow /= 0) then
-          if (this%gwtmodel2%oc%oc_save('BUDGET')) then
-            !
-            ! -- set nodestr and write outputtab table
-            nodeu = this%gwtmodel2%dis%get_nodeuser(n2)
-            call this%gwtmodel2%dis%nodeu_to_string(nodeu, nodestr)
-            call this%outputtab2%print_list_entry(i, trim(adjustl(nodestr)), &
-                                                  -rrate, bname)
-          end if
-        end if
-        if (rrate < DZERO) then
-          ratout = ratout - rrate
+      n1u = this%v_model1%dis_get_nodeuser(n1)
+      n2u = this%v_model2%dis_get_nodeuser(n2)
+      if (ibinun /= 0) then
+        if (is_for_model1) then
+          call model%dis%record_mf6_list_entry( &
+            ibinun, n1u, n2u, rrate, this%naux, this%auxvar(:, i), &
+            .false., .false.)
         else
-          ratin = ratin + rrate
+          call model%dis%record_mf6_list_entry( &
+            ibinun, n2u, n1u, -rrate, this%naux, this%auxvar(:, i), &
+            .false., .false.)
         end if
       end if
       !
-      ! -- If saving cell-by-cell flows in list, write flow
-      n1u = this%gwtmodel1%dis%get_nodeuser(n1)
-      n2u = this%gwtmodel2%dis%get_nodeuser(n2)
-      if (ibinun2 /= 0) &
-        call this%gwtmodel2%dis%record_mf6_list_entry( &
-        ibinun2, n2u, n1u, -rrate, this%naux, this%auxvar(:, i), &
-        .false., .false.)
-      !
     end do
     !
-    ! -- Set icbcfl, ibudfl to zero so that flows will be printed and
-    !    saved, if the options were set in the MVT package
-    icbcfl = 1
-    ibudfl = 1
-    !
-    ! -- Call mvt bd routine
-    !cdl todo: if(this%inmvt > 0) call this%mvt%mvt_bdsav(icbcfl, ibudfl, isuppress_output)
-    !
-    ! -- Calculate and write simulated values for observations
-    if (this%inobs /= 0) then
-      call this%gwt_gwt_save_simvals()
-    end if
-    !
-    ! -- return
+    ! -- Return
     return
-  end subroutine gwt_gwt_bdsav
+  end subroutine gwt_gwt_bdsav_model
 
   !> @ brief Output
   !!
   !! Write output
-  !!
   !<
   subroutine gwt_gwt_ot(this)
     ! -- modules
     use SimVariablesModule, only: iout
-    use ConstantsModule, only: DZERO, LINELENGTH
+    use ConstantsModule, only: DZERO
     ! -- dummy
     class(GwtExchangeType) :: this !<  GwtExchangeType
     ! -- local
@@ -722,12 +670,12 @@ subroutine gwt_gwt_ot(this)
         n1 = this%nodem1(iexg)
         n2 = this%nodem2(iexg)
         flow = this%simvals(iexg)
-        call this%gwtmodel1%dis%noder_to_string(n1, node1str)
-        call this%gwtmodel2%dis%noder_to_string(n2, node2str)
+        call this%v_model1%dis_noder_to_string(n1, node1str)
+        call this%v_model2%dis_noder_to_string(n2, node2str)
         write (iout, fmtdata) trim(adjustl(node1str)), &
           trim(adjustl(node2str)), &
-          this%cond(iexg), this%gwtmodel1%x(n1), &
-          this%gwtmodel2%x(n2), flow
+          this%cond(iexg), this%v_model1%x%get(n1), &
+          this%v_model2%x%get(n2), flow
       end do
     end if
     !
@@ -739,214 +687,117 @@ subroutine gwt_gwt_ot(this)
     ! -- OBS output
     call this%obs%obs_ot()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwt_gwt_ot
 
-  !> @ brief Read options
-  !!
-  !! Read the options block
+  !> @ brief Source options
   !!
+  !! Source the options block
   !<
-  subroutine read_options(this, iout)
+  subroutine source_options(this, iout)
     ! -- modules
-    use ConstantsModule, only: LINELENGTH, LENAUXNAME, DEM6
-    use MemoryManagerModule, only: mem_allocate
-    use SimModule, only: store_error, store_error_unit
+    use ConstantsModule, only: LENVARNAME
+    use InputOutputModule, only: getunit, openfile
+    use MemoryManagerExtModule, only: mem_set_value
+    use CharacterStringModule, only: CharacterStringType
+    use ExgGwtgwtInputModule, only: ExgGwtgwtParamFoundType
+    use SourceCommonModule, only: filein_fname
     ! -- dummy
     class(GwtExchangeType) :: this !<  GwtExchangeType
     integer(I4B), intent(in) :: iout
     ! -- local
-    character(len=LINELENGTH) :: keyword
-    logical :: isfound
-    logical :: endOfBlock
-    integer(I4B) :: ierr
-    !
-    ! -- get options block
-    call this%parser%GetBlock('OPTIONS', isfound, ierr, &
-                              supportOpenClose=.true., blockRequired=.false.)
-    !
-    ! -- parse options block if detected
-    if (isfound) then
-      write (iout, '(1x,a)') 'PROCESSING GWT-GWT EXCHANGE OPTIONS'
-      do
-        call this%parser%GetNextLine(endOfBlock)
-        if (endOfBlock) then
-          exit
-        end if
-        call this%parser%GetStringCaps(keyword)
-
-        ! first parse option in base
-        if (this%DisConnExchangeType%parse_option(keyword, iout)) then
-          cycle
-        end if
-
-        ! it's probably ours
-        if (this%parse_option(keyword, iout)) then
-          cycle
-        end if
-
-        ! unknown option
-        errmsg = "Unknown GWT-GWT exchange option '"//trim(keyword)//"'."
-        call store_error(errmsg)
-        call this%parser%StoreErrorUnit()
-      end do
-
-      write (iout, '(1x,a)') 'END OF GWT-GWT EXCHANGE OPTIONS'
-    end if
-    !
-    ! -- return
-    return
-  end subroutine read_options
-
-  !> @brief parse option from exchange file
-  !<
-  function parse_option(this, keyword, iout) result(parsed)
-    use InputOutputModule, only: getunit, openfile
-    class(GwtExchangeType) :: this !<  GwtExchangeType
-    character(len=LINELENGTH), intent(in) :: keyword !< the option name
-    integer(I4B), intent(in) :: iout !< for logging
-    logical(LGP) :: parsed !< true when parsed
-    ! local
-    character(len=LINELENGTH) :: fname
-    integer(I4B) :: inobs, ilen
-    character(len=LINELENGTH) :: subkey
-
-    parsed = .true.
-
-    select case (keyword)
-    case ('GWFMODELNAME1')
-      call this%parser%GetStringCaps(subkey)
-      ilen = len_trim(subkey)
-      if (ilen > LENMODELNAME) then
-        write (errmsg, '(a,a)') &
-          'Invalid model name: ', trim(subkey)
-        call store_error(errmsg)
-        call this%parser%StoreErrorUnit()
-      end if
-      if (this%gwfmodelname1 /= '') then
-        call store_error('GWFMODELNAME1 has already been set to ' &
-                         //trim(this%gwfmodelname1)// &
-                         '. Cannot set more than once.')
-        call this%parser%StoreErrorUnit()
-      end if
-      this%gwfmodelname1 = subkey(1:LENMODELNAME)
+    type(ExgGwtgwtParamFoundType) :: found
+    character(len=LENVARNAME), dimension(3) :: adv_scheme = &
+      &[character(len=LENVARNAME) :: 'UPSTREAM', 'CENTRAL', 'TVD']
+    character(len=LINELENGTH) :: mvt_fname
+    !
+    ! -- update defaults with values sourced from input context
+    call mem_set_value(this%gwfmodelname1, 'GWFMODELNAME1', this%input_mempath, &
+                       found%gwfmodelname1)
+    call mem_set_value(this%gwfmodelname2, 'GWFMODELNAME2', this%input_mempath, &
+                       found%gwfmodelname2)
+    call mem_set_value(this%iAdvScheme, 'ADV_SCHEME', this%input_mempath, &
+                       adv_scheme, found%adv_scheme)
+    call mem_set_value(this%ixt3d, 'DSP_XT3D_OFF', this%input_mempath, &
+                       found%dsp_xt3d_off)
+    call mem_set_value(this%ixt3d, 'DSP_XT3D_RHS', this%input_mempath, &
+                       found%dsp_xt3d_rhs)
+    !
+    write (iout, '(1x,a)') 'PROCESSING GWT-GWT EXCHANGE OPTIONS'
+    !
+    ! -- source base class options
+    call this%DisConnExchangeType%source_options(iout)
+    !
+    if (found%gwfmodelname1) then
       write (iout, '(4x,a,a)') &
         'GWFMODELNAME1 IS SET TO: ', trim(this%gwfmodelname1)
-    case ('GWFMODELNAME2')
-      call this%parser%GetStringCaps(subkey)
-      ilen = len_trim(subkey)
-      if (ilen > LENMODELNAME) then
-        write (errmsg, '(a,a)') &
-          'Invalid model name: ', trim(subkey)
-        call store_error(errmsg)
-        call this%parser%StoreErrorUnit()
-      end if
-      if (this%gwfmodelname2 /= '') then
-        call store_error('GWFMODELNAME2 has already been set to ' &
-                         //trim(this%gwfmodelname2)// &
-                         '. Cannot set more than once.')
-        call this%parser%StoreErrorUnit()
-      end if
-      this%gwfmodelname2 = subkey(1:LENMODELNAME)
+    end if
+    !
+    if (found%gwfmodelname2) then
       write (iout, '(4x,a,a)') &
         'GWFMODELNAME2 IS SET TO: ', trim(this%gwfmodelname2)
-    case ('PRINT_FLOWS')
-      this%iprflow = 1
-      write (iout, '(4x,a)') &
-        'EXCHANGE FLOWS WILL BE PRINTED TO LIST FILES.'
-    case ('SAVE_FLOWS')
-      this%ipakcb = -1
-      write (iout, '(4x,a)') &
-        'EXCHANGE FLOWS WILL BE SAVED TO BINARY BUDGET FILES.'
-    case ('MVT6')
-      call this%parser%GetStringCaps(subkey)
-      if (subkey /= 'FILEIN') then
-        call store_error('MVT6 keyword must be followed by '// &
-                         '"FILEIN" then by filename.')
-        call this%parser%StoreErrorUnit()
-      end if
-      call this%parser%GetString(fname)
-      if (fname == '') then
-        call store_error('No MVT6 file specified.')
-        call this%parser%StoreErrorUnit()
-      end if
-      this%inmvt = getunit()
-      call openfile(this%inmvt, iout, fname, 'MVT')
-      write (iout, '(4x,a)') &
-        'WATER MOVER TRANSPORT INFORMATION WILL BE READ FROM ', trim(fname)
-    case ('OBS6')
-      call this%parser%GetStringCaps(subkey)
-      if (subkey /= 'FILEIN') then
-        call store_error('OBS8 keyword must be followed by '// &
-                         '"FILEIN" then by filename.')
-        call this%parser%StoreErrorUnit()
-      end if
-      this%obs%active = .true.
-      call this%parser%GetString(this%obs%inputFilename)
-      inobs = GetUnit()
-      call openfile(inobs, iout, this%obs%inputFilename, 'OBS')
-      this%obs%inUnitObs = inobs
-    case ('ADV_SCHEME')
-      call this%parser%GetStringCaps(subkey)
-      select case (subkey)
-      case ('UPSTREAM')
-        this%iAdvScheme = 0
-      case ('CENTRAL')
-        this%iAdvScheme = 1
-      case ('TVD')
-        this%iAdvScheme = 2
-      case default
-        errmsg = "Unknown weighting method for advection: '"//trim(subkey)//"'."
-        call store_error(errmsg)
-        call this%parser%StoreErrorUnit()
-      end select
+    end if
+    !
+    if (found%adv_scheme) then
+      ! -- count from 0
+      this%iAdvScheme = this%iAdvScheme - 1
       write (iout, '(4x,a,a)') &
-        'CELL AVERAGING METHOD HAS BEEN SET TO: ', trim(subkey)
-    case ('DSP_XT3D_OFF')
+        'ADVECTION SCHEME METHOD HAS BEEN SET TO: ', &
+        trim(adv_scheme(this%iAdvScheme + 1))
+    end if
+    !
+    if (found%dsp_xt3d_off .and. found%dsp_xt3d_rhs) then
+      errmsg = 'DSP_XT3D_OFF and DSP_XT3D_RHS cannot both be set as options.'
+      call store_error(errmsg)
+      call store_error_filename(this%filename)
+    else if (found%dsp_xt3d_off) then
       this%ixt3d = 0
       write (iout, '(4x,a)') 'XT3D FORMULATION HAS BEEN SHUT OFF.'
-    case ('DSP_XT3D_RHS')
+    else if (found%dsp_xt3d_rhs) then
       this%ixt3d = 2
       write (iout, '(4x,a)') 'XT3D RIGHT-HAND SIDE FORMULATION IS SELECTED.'
-    case ('ADVSCHEME')
-      errmsg = 'ADVSCHEME is no longer a valid keyword.  Use ADV_SCHEME &
-        &instead.'
-      call store_error(errmsg)
-      call this%parser%StoreErrorUnit()
-    case ('XT3D_OFF')
-      errmsg = 'XT3D_OFF is no longer a valid keyword.  Use DSP_XT3D_OFF &
-        &instead.'
-      call store_error(errmsg)
-      call this%parser%StoreErrorUnit()
-    case ('XT3D_RHS')
-      errmsg = 'XT3D_RHS is no longer a valid keyword.  Use DSP_XT3D_RHS &
-        &instead.'
-      call store_error(errmsg)
-      call this%parser%StoreErrorUnit()
-    case default
-      parsed = .false.
-    end select
-
-  end function parse_option
+    end if
+    !
+    ! -- enforce 0 or 1 MVR6_FILENAME entries in option block
+    if (filein_fname(mvt_fname, 'MVT6_FILENAME', this%input_mempath, &
+                     this%filename)) then
+      this%inmvt = getunit()
+      call openfile(this%inmvt, iout, mvt_fname, 'MVT')
+      write (iout, '(4x,a)') &
+        'WATER MOVER TRANSPORT INFORMATION WILL BE READ FROM ', trim(mvt_fname)
+    end if
+    !
+    ! -- enforce 0 or 1 OBS6_FILENAME entries in option block
+    if (filein_fname(this%obs%inputFilename, 'OBS6_FILENAME', &
+                     this%input_mempath, this%filename)) then
+      this%obs%active = .true.
+      this%obs%inUnitObs = GetUnit()
+      call openfile(this%obs%inUnitObs, iout, this%obs%inputFilename, 'OBS')
+    end if
+    !
+    write (iout, '(1x,a)') 'END OF GWT-GWT EXCHANGE OPTIONS'
+    !
+    ! -- return
+    return
+  end subroutine source_options
 
   !> @ brief Read mover
   !!
   !! Read and process movers
-  !!
   !<
   subroutine read_mvt(this, iout)
     ! -- modules
-    use GwtMvtModule, only: mvt_cr
+    use TspMvtModule, only: mvt_cr
     ! -- dummy
     class(GwtExchangeType) :: this !<  GwtExchangeType
     integer(I4B), intent(in) :: iout
-    ! -- local
     !
     ! -- Create and initialize the mover object  Here, fmi is set to the one
     !    for gwtmodel1 so that a call to save flows has an associated dis
     !    object.
     call mvt_cr(this%mvt, this%name, this%inmvt, iout, this%gwtmodel1%fmi, &
+                this%gwtmodel1%eqnsclfac, &
                 gwfmodelname1=this%gwfmodelname1, &
                 gwfmodelname2=this%gwfmodelname2, &
                 fmi2=this%gwtmodel2%fmi)
@@ -958,7 +809,6 @@ end subroutine read_mvt
   !> @ brief Allocate scalars
   !!
   !! Allocate scalar variables
-  !!
   !<
   subroutine allocate_scalars(this)
     ! -- modules
@@ -966,40 +816,32 @@ subroutine allocate_scalars(this)
     use ConstantsModule, only: DZERO
     ! -- dummy
     class(GwtExchangeType) :: this !<  GwtExchangeType
-    ! -- local
     !
     call this%DisConnExchangeType%allocate_scalars()
     !
     call mem_allocate(this%inewton, 'INEWTON', this%memoryPath)
-    call mem_allocate(this%iprflow, 'IPRFLOW', this%memoryPath)
-    call mem_allocate(this%ipakcb, 'IPAKCB', this%memoryPath)
     call mem_allocate(this%inobs, 'INOBS', this%memoryPath)
     call mem_allocate(this%iAdvScheme, 'IADVSCHEME', this%memoryPath)
     this%inewton = 0
-    this%iprpak = 0
-    this%iprflow = 0
-    this%ipakcb = 0
     this%inobs = 0
     this%iAdvScheme = 0
     !
     call mem_allocate(this%inmvt, 'INMVT', this%memoryPath)
     this%inmvt = 0
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine allocate_scalars
 
   !> @ brief Deallocate
   !!
   !! Deallocate memory associated with this object
-  !!
   !<
   subroutine gwt_gwt_da(this)
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(GwtExchangeType) :: this !<  GwtExchangeType
-    ! -- local
     !
     ! -- objects
     if (this%inmvt > 0) then
@@ -1029,8 +871,6 @@ subroutine gwt_gwt_da(this)
     ! -- scalars
     deallocate (this%filename)
     call mem_deallocate(this%inewton)
-    call mem_deallocate(this%iprflow)
-    call mem_deallocate(this%ipakcb)
     call mem_deallocate(this%inobs)
     call mem_deallocate(this%iAdvScheme)
     call mem_deallocate(this%inmvt)
@@ -1038,14 +878,13 @@ subroutine gwt_gwt_da(this)
     ! -- deallocate base
     call this%DisConnExchangeType%disconnex_da()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwt_gwt_da
 
   !> @ brief Allocate arrays
   !!
   !! Allocate arrays
-  !!
   !<
   subroutine allocate_arrays(this)
     ! -- modules
@@ -1077,43 +916,46 @@ subroutine allocate_arrays(this)
       !
       ! -- initialize the output table objects
       !    outouttab1
-      call table_cr(this%outputtab1, this%name, '    ')
-      call this%outputtab1%table_df(this%nexg, ntabcol, this%gwtmodel1%iout, &
-                                    transient=.TRUE.)
-      text = 'NUMBER'
-      call this%outputtab1%initialize_column(text, 10, alignment=TABCENTER)
-      text = 'CELLID'
-      call this%outputtab1%initialize_column(text, 20, alignment=TABLEFT)
-      text = 'RATE'
-      call this%outputtab1%initialize_column(text, 15, alignment=TABCENTER)
-      if (this%inamedbound > 0) then
-        text = 'NAME'
+      if (this%v_model1%is_local) then
+        call table_cr(this%outputtab1, this%name, '    ')
+        call this%outputtab1%table_df(this%nexg, ntabcol, this%gwtmodel1%iout, &
+                                      transient=.TRUE.)
+        text = 'NUMBER'
+        call this%outputtab1%initialize_column(text, 10, alignment=TABCENTER)
+        text = 'CELLID'
         call this%outputtab1%initialize_column(text, 20, alignment=TABLEFT)
+        text = 'RATE'
+        call this%outputtab1%initialize_column(text, 15, alignment=TABCENTER)
+        if (this%inamedbound > 0) then
+          text = 'NAME'
+          call this%outputtab1%initialize_column(text, 20, alignment=TABLEFT)
+        end if
       end if
       !    outouttab2
-      call table_cr(this%outputtab2, this%name, '    ')
-      call this%outputtab2%table_df(this%nexg, ntabcol, this%gwtmodel2%iout, &
-                                    transient=.TRUE.)
-      text = 'NUMBER'
-      call this%outputtab2%initialize_column(text, 10, alignment=TABCENTER)
-      text = 'CELLID'
-      call this%outputtab2%initialize_column(text, 20, alignment=TABLEFT)
-      text = 'RATE'
-      call this%outputtab2%initialize_column(text, 15, alignment=TABCENTER)
-      if (this%inamedbound > 0) then
-        text = 'NAME'
+      if (this%v_model2%is_local) then
+        call table_cr(this%outputtab2, this%name, '    ')
+        call this%outputtab2%table_df(this%nexg, ntabcol, this%gwtmodel2%iout, &
+                                      transient=.TRUE.)
+        text = 'NUMBER'
+        call this%outputtab2%initialize_column(text, 10, alignment=TABCENTER)
+        text = 'CELLID'
         call this%outputtab2%initialize_column(text, 20, alignment=TABLEFT)
+        text = 'RATE'
+        call this%outputtab2%initialize_column(text, 15, alignment=TABCENTER)
+        if (this%inamedbound > 0) then
+          text = 'NAME'
+          call this%outputtab2%initialize_column(text, 20, alignment=TABLEFT)
+        end if
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine allocate_arrays
 
   !> @ brief Define observations
   !!
   !! Define the observations associated with this object
-  !!
   !<
   subroutine gwt_gwt_df_obs(this)
     ! -- dummy
@@ -1126,14 +968,13 @@ subroutine gwt_gwt_df_obs(this)
     call this%obs%StoreObsType('flow-ja-face', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => gwt_gwt_process_obsID
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwt_gwt_df_obs
 
   !> @ brief Read and prepare observations
   !!
   !! Handle observation exchanges exchange-boundary names.
-  !!
   !<
   subroutine gwt_gwt_rp_obs(this)
     ! -- modules
@@ -1198,7 +1039,7 @@ subroutine gwt_gwt_rp_obs(this)
     !
     ! -- write summary of error messages
     if (count_errors() > 0) then
-      call store_error_unit(this%inobs)
+      call store_error_filename(this%obs%inputFilename)
     end if
     !
     ! -- Return
@@ -1208,24 +1049,27 @@ end subroutine gwt_gwt_rp_obs
   !> @ brief Final processing
   !!
   !! Conduct any final processing
-  !!
   !<
   subroutine gwt_gwt_fp(this)
     ! -- dummy
     class(GwtExchangeType) :: this !<  GwtExchangeType
     !
+    ! -- Return
     return
   end subroutine gwt_gwt_fp
 
-  !> @brief Return true when this exchange provides matrix
-  !! coefficients for solving @param model
+  !> @brief Return true when this exchange provides matrix coefficients for
+  !! solving @param model
   !<
   function gwt_gwt_connects_model(this, model) result(is_connected)
+    ! -- dummy
     class(GwtExchangeType) :: this !<  GwtExchangeType
     class(BaseModelType), pointer, intent(in) :: model !< the model to which the exchange might hold a connection
+    ! -- return
     logical(LGP) :: is_connected !< true, when connected
-
+    !
     is_connected = .false.
+    !
     ! only connected when model is GwtModelType of course
     select type (model)
     class is (GwtModelType)
@@ -1235,7 +1079,9 @@ function gwt_gwt_connects_model(this, model) result(is_connected)
         is_connected = .true.
       end if
     end select
-
+    !
+    ! -- Return
+    return
   end function gwt_gwt_connects_model
 
   !> @brief Should interface model be used for this exchange
@@ -1247,23 +1093,25 @@ end function gwt_gwt_connects_model
   !! set the return accordingly.
   !<
   function use_interface_model(this) result(use_im)
+    ! -- dummy
     class(GwtExchangeType) :: this !<  GwtExchangeType
+    ! -- return
     logical(LGP) :: use_im !< true when interface model should be used
-
+    !
     ! For now set use_im to .true. since the interface model approach
     ! must currently be used for any GWT-GWT exchange.
     use_im = .true.
-
+    !
+    ! -- Return
+    return
   end function
 
   !> @ brief Save simulated flow observations
   !!
   !! Save the simulated flows for each exchange
-  !!
   !<
   subroutine gwt_gwt_save_simvals(this)
     ! -- dummy
-    use SimModule, only: store_error, store_error_unit
     use SimVariablesModule, only: errmsg
     use ConstantsModule, only: DZERO
     use ObserveModule, only: ObserveType
@@ -1294,20 +1142,20 @@ subroutine gwt_gwt_save_simvals(this)
             errmsg = 'Unrecognized observation type: '// &
                      trim(obsrv%ObsTypeId)
             call store_error(errmsg)
-            call store_error_unit(this%inobs)
+            call store_error_filename(this%obs%inputFilename)
           end select
           call this%obs%SaveOneSimval(obsrv, v)
         end do
       end do
     end if
     !
+    ! -- Return
     return
   end subroutine gwt_gwt_save_simvals
 
   !> @ brief Obs ID processer
   !!
   !! Process observations for this exchange
-  !!
   !<
   subroutine gwt_gwt_process_obsID(obsrv, dis, inunitobs, iout)
     ! -- modules
@@ -1343,17 +1191,19 @@ subroutine gwt_gwt_process_obsID(obsrv, dis, inunitobs, iout)
       obsrv%intPak1 = NAMEDBOUNDFLAG
     end if
     !
+    ! -- Return
     return
   end subroutine gwt_gwt_process_obsID
 
   !> @ brief Cast polymorphic object as exchange
   !!
   !! Cast polymorphic object as exchange
-  !!
   !<
   function CastAsGwtExchange(obj) result(res)
     implicit none
+    ! -- dummy
     class(*), pointer, intent(inout) :: obj
+    ! -- return
     class(GwtExchangeType), pointer :: res
     !
     res => null()
@@ -1363,19 +1213,21 @@ function CastAsGwtExchange(obj) result(res)
     class is (GwtExchangeType)
       res => obj
     end select
+    !
+    ! -- Return
     return
   end function CastAsGwtExchange
 
   !> @ brief Get exchange from list
   !!
   !! Return an exchange from the list for specified index
-  !!
   !<
   function GetGwtExchangeFromList(list, idx) result(res)
     implicit none
     ! -- dummy
     type(ListType), intent(inout) :: list
     integer(I4B), intent(in) :: idx
+    ! -- return
     class(GwtExchangeType), pointer :: res
     ! -- local
     class(*), pointer :: obj
@@ -1383,6 +1235,7 @@ function GetGwtExchangeFromList(list, idx) result(res)
     obj => list%GetItem(idx)
     res => CastAsGwtExchange(obj)
     !
+    ! -- Return
     return
   end function GetGwtExchangeFromList
 
diff --git a/src/Exchange/NumericalExchange.f90 b/src/Exchange/NumericalExchange.f90
index 0d40eac262d..f2765dadec7 100644
--- a/src/Exchange/NumericalExchange.f90
+++ b/src/Exchange/NumericalExchange.f90
@@ -15,7 +15,9 @@ module NumericalExchangeModule
 
   type, extends(BaseExchangeType) :: NumericalExchangeType
     character(len=7) :: typename !< name of the type (e.g., 'GWF-GWF')
+
   contains
+
     procedure :: exg_df
     procedure :: exg_ac
     procedure :: exg_mc
@@ -34,155 +36,104 @@ module NumericalExchangeModule
 
 contains
 
+  !> @brief Define the exchange
+  !<
   subroutine exg_df(this)
-! ******************************************************************************
-! exg_df -- define the exchange
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use BaseModelModule, only: BaseModelType
     use InputOutputModule, only: getunit, openfile
     ! -- dummy
     class(NumericalExchangeType) :: this
-    ! -- local
-! ------------------------------------------------------------------------------
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine exg_df
 
+  !> @brief If an implicit exchange then add connections to sparse
+  !<
   subroutine exg_ac(this, sparse)
-! ******************************************************************************
-! exg_ac -- If an implicit exchange then add connections to sparse
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SparseModule, only: sparsematrix
     ! -- dummy
     class(NumericalExchangeType) :: this
     type(sparsematrix), intent(inout) :: sparse
-    ! -- local
-! ------------------------------------------------------------------------------
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine exg_ac
 
+  !> @brief Map the connections in the global matrix
+  !<
   subroutine exg_mc(this, matrix_sln)
-! ******************************************************************************
-! exg_mc -- Map the connections in the global matrix
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- module
     use SparseModule, only: sparsematrix
     ! -- dummy
     class(NumericalExchangeType) :: this
     class(MatrixBaseType), pointer :: matrix_sln
-    ! -- local
-! ------------------------------------------------------------------------------
     !
-    ! -- return
+    ! -- Return
   end subroutine exg_mc
 
+  !> @brief Allocate and read
+  !<
   subroutine exg_ar(this)
-! ******************************************************************************
-! exg_ar -- Allocate and read
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    !
     class(NumericalExchangeType) :: this
-! ------------------------------------------------------------------------------
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine exg_ar
 
+  !> @brief Advance
+  !<
   subroutine exg_ad(this)
-! ******************************************************************************
-! exg_ad -- Advance
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(NumericalExchangeType) :: this
-    ! -- local
-! ------------------------------------------------------------------------------
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine exg_ad
 
+  !> @brief Calculate conductance, and for explicit exchanges, set the
+  !! conductance in the boundary package
+  !<
   subroutine exg_cf(this, kiter)
-! ******************************************************************************
-! exg_cf -- Calculate conductance, and for explicit exchanges, set the
-!   conductance in the boundary package.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(NumericalExchangeType) :: this
     integer(I4B), intent(in) :: kiter
-    ! -- local
-! ------------------------------------------------------------------------------
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine exg_cf
 
+  !> @brief Fill the matrix
+  !<
   subroutine exg_fc(this, kiter, matrix_sln, rhs_sln, inwtflag)
-! ******************************************************************************
-! exg_fc -- Fill the matrix
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(NumericalExchangeType) :: this
     integer(I4B), intent(in) :: kiter
     class(MatrixBaseType), pointer :: matrix_sln
     real(DP), dimension(:), intent(inout) :: rhs_sln
     integer(I4B), optional, intent(in) :: inwtflag
-    ! -- local
-! ------------------------------------------------------------------------------
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine exg_fc
 
+  !> @brief Additional convergence check
+  !<
   subroutine exg_cc(this, icnvg)
-! ******************************************************************************
-! exg_cc -- Additional convergence check
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(NumericalExchangeType) :: this
     integer(I4B), intent(inout) :: icnvg
-    ! -- local
-! ------------------------------------------------------------------------------
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine exg_cc
 
+  !> @brief Calculate flow
+  !<
   subroutine exg_cq(this, icnvg, isuppress_output, isolnid)
-! ******************************************************************************
-! exg_cq -- Calculate flow
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LENBUDTXT
     ! -- dummy
@@ -190,20 +141,14 @@ subroutine exg_cq(this, icnvg, isuppress_output, isolnid)
     integer(I4B), intent(inout) :: icnvg
     integer(I4B), intent(in) :: isuppress_output
     integer(I4B), intent(in) :: isolnid
-    ! -- local
-! ------------------------------------------------------------------------------
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine exg_cq
 
+  !> @brief Exchange budget
+  !<
   subroutine exg_bd(this, icnvg, isuppress_output, isolnid)
-! ******************************************************************************
-! exg_bd -- Exchange budget
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LENBUDTXT
     ! -- dummy
@@ -211,56 +156,50 @@ subroutine exg_bd(this, icnvg, isuppress_output, isolnid)
     integer(I4B), intent(inout) :: icnvg
     integer(I4B), intent(in) :: isuppress_output
     integer(I4B), intent(in) :: isolnid
-    ! -- local
-! ------------------------------------------------------------------------------
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine exg_bd
 
+  !> @brief Output
+  !<
   subroutine exg_ot(this)
-! ******************************************************************************
-! exg_ot
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(NumericalExchangeType) :: this
-! ------------------------------------------------------------------------------
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine exg_ot
 
+  !> @brief Deallocate memory
+  !<
   subroutine exg_da(this)
-! ******************************************************************************
-! exg_da
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(NumericalExchangeType) :: this
-    ! -- local
-! ------------------
-
+    !
+    ! -- Return
     return
   end subroutine exg_da
 
   function get_iasym(this) result(iasym)
+    ! -- dummy
     class(NumericalExchangeType) :: this
+    ! -- return
     integer(I4B) :: iasym
-
+    !
     iasym = 0
-
+    !
+    ! -- Return
+    return
   end function get_iasym
 
   function CastAsNumericalExchangeClass(obj) result(res)
     implicit none
+    ! -- dummy
     class(*), pointer, intent(inout) :: obj
+    ! -- return
     class(NumericalExchangeType), pointer :: res
     !
     res => null()
@@ -270,9 +209,13 @@ function CastAsNumericalExchangeClass(obj) result(res)
     class is (NumericalExchangeType)
       res => obj
     end select
+    !
+    ! -- Return
     return
   end function CastAsNumericalExchangeClass
 
+  !> @brief Add numerical exchange to a list
+  !<
   subroutine AddNumericalExchangeToList(list, exchange)
     implicit none
     ! -- dummy
@@ -284,9 +227,12 @@ subroutine AddNumericalExchangeToList(list, exchange)
     obj => exchange
     call list%Add(obj)
     !
+    ! -- Return
     return
   end subroutine AddNumericalExchangeToList
 
+  !> @brief Retrieve a specific numerical exchange from a list
+  !<
   function GetNumericalExchangeFromList(list, idx) result(res)
     implicit none
     ! -- dummy
@@ -299,6 +245,7 @@ function GetNumericalExchangeFromList(list, idx) result(res)
     obj => list%GetItem(idx)
     res => CastAsNumericalExchangeClass(obj)
     !
+    ! -- Return
     return
   end function GetNumericalExchangeFromList
 
diff --git a/src/Exchange/gwfgwfidm.f90 b/src/Exchange/gwfgwfidm.f90
new file mode 100644
index 00000000000..888f6422cb1
--- /dev/null
+++ b/src/Exchange/gwfgwfidm.f90
@@ -0,0 +1,658 @@
+! ** Do Not Modify! MODFLOW 6 system generated file. **
+module ExgGwfgwfInputModule
+  use ConstantsModule, only: LENVARNAME
+  use InputDefinitionModule, only: InputParamDefinitionType, &
+                                   InputBlockDefinitionType
+  private
+  public exg_gwfgwf_param_definitions
+  public exg_gwfgwf_aggregate_definitions
+  public exg_gwfgwf_block_definitions
+  public ExgGwfgwfParamFoundType
+  public exg_gwfgwf_multi_package
+
+  type ExgGwfgwfParamFoundType
+    logical :: auxiliary = .false.
+    logical :: boundnames = .false.
+    logical :: iprpak = .false.
+    logical :: iprflow = .false.
+    logical :: ipakcb = .false.
+    logical :: cell_averaging = .false.
+    logical :: cvoptions = .false.
+    logical :: variablecv = .false.
+    logical :: dewatered = .false.
+    logical :: newton = .false.
+    logical :: xt3d = .false.
+    logical :: gnc_filerecord = .false.
+    logical :: filein = .false.
+    logical :: gnc6 = .false.
+    logical :: gnc6_filename = .false.
+    logical :: mvr_filerecord = .false.
+    logical :: mvr6 = .false.
+    logical :: mvr6_filename = .false.
+    logical :: obs_filerecord = .false.
+    logical :: obs6 = .false.
+    logical :: obs6_filename = .false.
+    logical :: dev_ifmod_on = .false.
+    logical :: nexg = .false.
+    logical :: cellidm1 = .false.
+    logical :: cellidm2 = .false.
+    logical :: ihc = .false.
+    logical :: cl1 = .false.
+    logical :: cl2 = .false.
+    logical :: hwva = .false.
+    logical :: aux = .false.
+    logical :: boundname = .false.
+  end type ExgGwfgwfParamFoundType
+
+  logical :: exg_gwfgwf_multi_package = .true.
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_auxiliary = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXILIARY', & ! tag name
+    'AUXILIARY', & ! fortran variable
+    'STRING', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_boundnames = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'BOUNDNAMES', & ! tag name
+    'BOUNDNAMES', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_iprpak = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_INPUT', & ! tag name
+    'IPRPAK', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_iprflow = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_FLOWS', & ! tag name
+    'IPRFLOW', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_ipakcb = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'SAVE_FLOWS', & ! tag name
+    'IPAKCB', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_cell_averaging = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'CELL_AVERAGING', & ! tag name
+    'CELL_AVERAGING', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_cvoptions = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'CVOPTIONS', & ! tag name
+    'CVOPTIONS', & ! fortran variable
+    'RECORD VARIABLECV DEWATERED', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_variablecv = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'VARIABLECV', & ! tag name
+    'VARIABLECV', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_dewatered = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'DEWATERED', & ! tag name
+    'DEWATERED', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_newton = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'NEWTON', & ! tag name
+    'NEWTON', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_xt3d = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'XT3D', & ! tag name
+    'XT3D', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_gnc_filerecord = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'GNC_FILERECORD', & ! tag name
+    'GNC_FILERECORD', & ! fortran variable
+    'RECORD GNC6 FILEIN GNC6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_filein = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'FILEIN', & ! tag name
+    'FILEIN', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_gnc6 = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'GNC6', & ! tag name
+    'GNC6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_gnc6_filename = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'GNC6_FILENAME', & ! tag name
+    'GNC6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_mvr_filerecord = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'MVR_FILERECORD', & ! tag name
+    'MVR_FILERECORD', & ! fortran variable
+    'RECORD MVR6 FILEIN MVR6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_mvr6 = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'MVR6', & ! tag name
+    'MVR6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_mvr6_filename = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'MVR6_FILENAME', & ! tag name
+    'MVR6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_obs_filerecord = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS_FILERECORD', & ! tag name
+    'OBS_FILERECORD', & ! fortran variable
+    'RECORD OBS6 FILEIN OBS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_obs6 = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6', & ! tag name
+    'OBS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_obs6_filename = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6_FILENAME', & ! tag name
+    'OBS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_dev_ifmod_on = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'OPTIONS', & ! block
+    'DEV_INTERFACEMODEL_ON', & ! tag name
+    'DEV_IFMOD_ON', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_nexg = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'DIMENSIONS', & ! block
+    'NEXG', & ! tag name
+    'NEXG', & ! fortran variable
+    'INTEGER', & ! type
+    '', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_cellidm1 = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'CELLIDM1', & ! tag name
+    'CELLIDM1', & ! fortran variable
+    'INTEGER1D', & ! type
+    'NCELLDIM', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_cellidm2 = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'CELLIDM2', & ! tag name
+    'CELLIDM2', & ! fortran variable
+    'INTEGER1D', & ! type
+    'NCELLDIM', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_ihc = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'IHC', & ! tag name
+    'IHC', & ! fortran variable
+    'INTEGER', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_cl1 = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'CL1', & ! tag name
+    'CL1', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_cl2 = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'CL2', & ! tag name
+    'CL2', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_hwva = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'HWVA', & ! tag name
+    'HWVA', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_aux = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'AUX', & ! tag name
+    'AUX', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_boundname = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'BOUNDNAME', & ! tag name
+    'BOUNDNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exg_gwfgwf_param_definitions(*) = &
+    [ &
+    exggwfgwf_auxiliary, &
+    exggwfgwf_boundnames, &
+    exggwfgwf_iprpak, &
+    exggwfgwf_iprflow, &
+    exggwfgwf_ipakcb, &
+    exggwfgwf_cell_averaging, &
+    exggwfgwf_cvoptions, &
+    exggwfgwf_variablecv, &
+    exggwfgwf_dewatered, &
+    exggwfgwf_newton, &
+    exggwfgwf_xt3d, &
+    exggwfgwf_gnc_filerecord, &
+    exggwfgwf_filein, &
+    exggwfgwf_gnc6, &
+    exggwfgwf_gnc6_filename, &
+    exggwfgwf_mvr_filerecord, &
+    exggwfgwf_mvr6, &
+    exggwfgwf_mvr6_filename, &
+    exggwfgwf_obs_filerecord, &
+    exggwfgwf_obs6, &
+    exggwfgwf_obs6_filename, &
+    exggwfgwf_dev_ifmod_on, &
+    exggwfgwf_nexg, &
+    exggwfgwf_cellidm1, &
+    exggwfgwf_cellidm2, &
+    exggwfgwf_ihc, &
+    exggwfgwf_cl1, &
+    exggwfgwf_cl2, &
+    exggwfgwf_hwva, &
+    exggwfgwf_aux, &
+    exggwfgwf_boundname &
+    ]
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwfgwf_exchangedata = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWFGWF', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'EXCHANGEDATA', & ! tag name
+    'EXCHANGEDATA', & ! fortran variable
+    'RECARRAY CELLIDM1 CELLIDM2 IHC CL1 CL2 HWVA AUX BOUNDNAME', & ! type
+    'NEXG', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exg_gwfgwf_aggregate_definitions(*) = &
+    [ &
+    exggwfgwf_exchangedata &
+    ]
+
+  type(InputBlockDefinitionType), parameter :: &
+    exg_gwfgwf_block_definitions(*) = &
+    [ &
+    InputBlockDefinitionType( &
+    'OPTIONS', & ! blockname
+    .false., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'DIMENSIONS', & ! blockname
+    .true., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'EXCHANGEDATA', & ! blockname
+    .true., & ! required
+    .true., & ! aggregate
+    .false. & ! block_variable
+    ) &
+    ]
+
+end module ExgGwfgwfInputModule
diff --git a/src/Exchange/gwfgwtidm.f90 b/src/Exchange/gwfgwtidm.f90
new file mode 100644
index 00000000000..30374514be3
--- /dev/null
+++ b/src/Exchange/gwfgwtidm.f90
@@ -0,0 +1,70 @@
+! ** Do Not Modify! MODFLOW 6 system generated file. **
+module ExgGwfgwtInputModule
+  use ConstantsModule, only: LENVARNAME
+  use InputDefinitionModule, only: InputParamDefinitionType, &
+                                   InputBlockDefinitionType
+  private
+  public exg_gwfgwt_param_definitions
+  public exg_gwfgwt_aggregate_definitions
+  public exg_gwfgwt_block_definitions
+  public ExgGwfgwtParamFoundType
+  public exg_gwfgwt_multi_package
+
+  type ExgGwfgwtParamFoundType
+  end type ExgGwfgwtParamFoundType
+
+  logical :: exg_gwfgwt_multi_package = .false.
+
+  type(InputParamDefinitionType), parameter :: &
+    exg_gwfgwt_param_definitions(*) = &
+    [ &
+    InputParamDefinitionType &
+    ( &
+    '', & ! component
+    '', & ! subcomponent
+    '', & ! block
+    '', & ! tag name
+    '', & ! fortran variable
+    '', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    ) &
+    ]
+
+  type(InputParamDefinitionType), parameter :: &
+    exg_gwfgwt_aggregate_definitions(*) = &
+    [ &
+    InputParamDefinitionType &
+    ( &
+    '', & ! component
+    '', & ! subcomponent
+    '', & ! block
+    '', & ! tag name
+    '', & ! fortran variable
+    '', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    ) &
+    ]
+
+  type(InputBlockDefinitionType), parameter :: &
+    exg_gwfgwt_block_definitions(*) = &
+    [ &
+    InputBlockDefinitionType &
+    ( &
+    '', & ! blockname
+    .false., & ! required
+    .false., & ! aggregate
+    .false. & ! block_varaible
+    ) &
+    ]
+
+end module ExgGwfgwtInputModule
diff --git a/src/Exchange/gwtgwtidm.f90 b/src/Exchange/gwtgwtidm.f90
new file mode 100644
index 00000000000..dba0074ce73
--- /dev/null
+++ b/src/Exchange/gwtgwtidm.f90
@@ -0,0 +1,582 @@
+! ** Do Not Modify! MODFLOW 6 system generated file. **
+module ExgGwtgwtInputModule
+  use ConstantsModule, only: LENVARNAME
+  use InputDefinitionModule, only: InputParamDefinitionType, &
+                                   InputBlockDefinitionType
+  private
+  public exg_gwtgwt_param_definitions
+  public exg_gwtgwt_aggregate_definitions
+  public exg_gwtgwt_block_definitions
+  public ExgGwtgwtParamFoundType
+  public exg_gwtgwt_multi_package
+
+  type ExgGwtgwtParamFoundType
+    logical :: gwfmodelname1 = .false.
+    logical :: gwfmodelname2 = .false.
+    logical :: auxiliary = .false.
+    logical :: boundnames = .false.
+    logical :: iprpak = .false.
+    logical :: iprflow = .false.
+    logical :: ipakcb = .false.
+    logical :: adv_scheme = .false.
+    logical :: dsp_xt3d_off = .false.
+    logical :: dsp_xt3d_rhs = .false.
+    logical :: filein = .false.
+    logical :: mvt_filerecord = .false.
+    logical :: mvt6 = .false.
+    logical :: mvt6_filename = .false.
+    logical :: obs_filerecord = .false.
+    logical :: obs6 = .false.
+    logical :: obs6_filename = .false.
+    logical :: dev_ifmod_on = .false.
+    logical :: nexg = .false.
+    logical :: cellidm1 = .false.
+    logical :: cellidm2 = .false.
+    logical :: ihc = .false.
+    logical :: cl1 = .false.
+    logical :: cl2 = .false.
+    logical :: hwva = .false.
+    logical :: aux = .false.
+    logical :: boundname = .false.
+  end type ExgGwtgwtParamFoundType
+
+  logical :: exg_gwtgwt_multi_package = .true.
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_gwfmodelname1 = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'GWFMODELNAME1', & ! tag name
+    'GWFMODELNAME1', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_gwfmodelname2 = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'GWFMODELNAME2', & ! tag name
+    'GWFMODELNAME2', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_auxiliary = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXILIARY', & ! tag name
+    'AUXILIARY', & ! fortran variable
+    'STRING', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_boundnames = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'BOUNDNAMES', & ! tag name
+    'BOUNDNAMES', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_iprpak = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_INPUT', & ! tag name
+    'IPRPAK', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_iprflow = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_FLOWS', & ! tag name
+    'IPRFLOW', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_ipakcb = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'SAVE_FLOWS', & ! tag name
+    'IPAKCB', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_adv_scheme = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'ADV_SCHEME', & ! tag name
+    'ADV_SCHEME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_dsp_xt3d_off = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'DSP_XT3D_OFF', & ! tag name
+    'DSP_XT3D_OFF', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_dsp_xt3d_rhs = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'DSP_XT3D_RHS', & ! tag name
+    'DSP_XT3D_RHS', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_filein = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'FILEIN', & ! tag name
+    'FILEIN', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_mvt_filerecord = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'MVT_FILERECORD', & ! tag name
+    'MVT_FILERECORD', & ! fortran variable
+    'RECORD MVT6 FILEIN MVT6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_mvt6 = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'MVT6', & ! tag name
+    'MVT6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_mvt6_filename = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'MVT6_FILENAME', & ! tag name
+    'MVT6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_obs_filerecord = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS_FILERECORD', & ! tag name
+    'OBS_FILERECORD', & ! fortran variable
+    'RECORD OBS6 FILEIN OBS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_obs6 = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6', & ! tag name
+    'OBS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_obs6_filename = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6_FILENAME', & ! tag name
+    'OBS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_dev_ifmod_on = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'OPTIONS', & ! block
+    'DEV_INTERFACEMODEL_ON', & ! tag name
+    'DEV_IFMOD_ON', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_nexg = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'DIMENSIONS', & ! block
+    'NEXG', & ! tag name
+    'NEXG', & ! fortran variable
+    'INTEGER', & ! type
+    '', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_cellidm1 = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'CELLIDM1', & ! tag name
+    'CELLIDM1', & ! fortran variable
+    'INTEGER1D', & ! type
+    'NCELLDIM', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_cellidm2 = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'CELLIDM2', & ! tag name
+    'CELLIDM2', & ! fortran variable
+    'INTEGER1D', & ! type
+    'NCELLDIM', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_ihc = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'IHC', & ! tag name
+    'IHC', & ! fortran variable
+    'INTEGER', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_cl1 = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'CL1', & ! tag name
+    'CL1', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_cl2 = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'CL2', & ! tag name
+    'CL2', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_hwva = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'HWVA', & ! tag name
+    'HWVA', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_aux = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'AUX', & ! tag name
+    'AUX', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_boundname = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'BOUNDNAME', & ! tag name
+    'BOUNDNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exg_gwtgwt_param_definitions(*) = &
+    [ &
+    exggwtgwt_gwfmodelname1, &
+    exggwtgwt_gwfmodelname2, &
+    exggwtgwt_auxiliary, &
+    exggwtgwt_boundnames, &
+    exggwtgwt_iprpak, &
+    exggwtgwt_iprflow, &
+    exggwtgwt_ipakcb, &
+    exggwtgwt_adv_scheme, &
+    exggwtgwt_dsp_xt3d_off, &
+    exggwtgwt_dsp_xt3d_rhs, &
+    exggwtgwt_filein, &
+    exggwtgwt_mvt_filerecord, &
+    exggwtgwt_mvt6, &
+    exggwtgwt_mvt6_filename, &
+    exggwtgwt_obs_filerecord, &
+    exggwtgwt_obs6, &
+    exggwtgwt_obs6_filename, &
+    exggwtgwt_dev_ifmod_on, &
+    exggwtgwt_nexg, &
+    exggwtgwt_cellidm1, &
+    exggwtgwt_cellidm2, &
+    exggwtgwt_ihc, &
+    exggwtgwt_cl1, &
+    exggwtgwt_cl2, &
+    exggwtgwt_hwva, &
+    exggwtgwt_aux, &
+    exggwtgwt_boundname &
+    ]
+
+  type(InputParamDefinitionType), parameter :: &
+    exggwtgwt_exchangedata = InputParamDefinitionType &
+    ( &
+    'EXG', & ! component
+    'GWTGWT', & ! subcomponent
+    'EXCHANGEDATA', & ! block
+    'EXCHANGEDATA', & ! tag name
+    'EXCHANGEDATA', & ! fortran variable
+    'RECARRAY CELLIDM1 CELLIDM2 IHC CL1 CL2 HWVA AUX BOUNDNAME', & ! type
+    'NEXG', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    exg_gwtgwt_aggregate_definitions(*) = &
+    [ &
+    exggwtgwt_exchangedata &
+    ]
+
+  type(InputBlockDefinitionType), parameter :: &
+    exg_gwtgwt_block_definitions(*) = &
+    [ &
+    InputBlockDefinitionType( &
+    'OPTIONS', & ! blockname
+    .true., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'DIMENSIONS', & ! blockname
+    .true., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'EXCHANGEDATA', & ! blockname
+    .true., & ! required
+    .true., & ! aggregate
+    .false. & ! block_variable
+    ) &
+    ]
+
+end module ExgGwtgwtInputModule
diff --git a/src/Model/BaseModel.f90 b/src/Model/BaseModel.f90
index 29a71992fd2..d33b2541b8f 100644
--- a/src/Model/BaseModel.f90
+++ b/src/Model/BaseModel.f90
@@ -1,5 +1,3 @@
-!Highest level model class.  All models inherit from this parent class.
-
 module BaseModelModule
 
   use KindModule, only: DP, I4B
@@ -11,9 +9,9 @@ module BaseModelModule
   public :: BaseModelType, CastAsBaseModelClass, AddBaseModelToList, &
             GetBaseModelFromList
 
+  !> @brief Highest level model type. All models extend this parent type.
   type :: BaseModelType
     character(len=LENMEMPATH) :: memoryPath !< the location in the memory manager where the variables are stored
-
     character(len=LENMODELNAME), pointer :: name => null() !< name of the model
     character(len=3), pointer :: macronym => null() !< 3 letter model acronym (GWF, GWT, ...)
     integer(I4B), pointer :: idsoln => null() !< id of the solution model is in
@@ -37,90 +35,45 @@ module BaseModelModule
 
 contains
 
+  !> @brief Define the model
+  !<
   subroutine model_df(this)
-! ******************************************************************************
-! modeldf -- Define the model
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     class(BaseModelType) :: this
-! ------------------------------------------------------------------------------
-    !
-    ! -- return
-    return
   end subroutine model_df
 
+  !> @brief Allocate and read
+  !<
   subroutine model_ar(this)
-! ******************************************************************************
-! modelar -- Allocate and read
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     class(BaseModelType) :: this
-! ------------------------------------------------------------------------------
-    !
-    ! -- return
-    return
   end subroutine model_ar
 
+  !> @brief Read and prepare
+  !<
   subroutine model_rp(this)
-! ******************************************************************************
-! model_rp -- Read and prepare
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     class(BaseModelType) :: this
-! ------------------------------------------------------------------------------
-    !
-    ! -- return
-    return
   end subroutine model_rp
 
+  !> @brief Calculate time step length
+  !<
   subroutine model_calculate_delt(this)
-! ******************************************************************************
-! model_calculate_delt -- Calculate time step length
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     class(BaseModelType) :: this
-! ------------------------------------------------------------------------------
-    !
-    ! -- return
-    return
   end subroutine model_calculate_delt
 
+  !> @brief Output results
+  !<
   subroutine model_ot(this)
-! ******************************************************************************
-! model_ot -- output results
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     class(BaseModelType) :: this
-! ------------------------------------------------------------------------------
-    !
-    ! -- return
-    return
   end subroutine model_ot
 
+  !> @brief Write line to model iout
+  !<
   subroutine model_message(this, line, fmt)
-! ******************************************************************************
-! model_message -- write line to model iout
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(BaseModelType) :: this
     character(len=*), intent(in) :: line
     character(len=*), intent(in), optional :: fmt
     ! -- local
     character(len=LINELENGTH) :: cfmt
-! ------------------------------------------------------------------------------
     !
     ! -- process optional variables
     if (present(fmt)) then
@@ -131,38 +84,22 @@ subroutine model_message(this, line, fmt)
     !
     ! -- write line
     write (this%iout, trim(cfmt)) trim(line)
-    !
-    ! -- return
-    return
   end subroutine model_message
 
+  !> @brief Final processing
+  !<
   subroutine model_fp(this)
-! ******************************************************************************
-! model_fp -- Final processing
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     class(BaseModelType) :: this
-! ------------------------------------------------------------------------------
-    !
-    ! -- return
-    return
   end subroutine model_fp
 
+  !> @brief Allocate scalar variables
+  !<
   subroutine allocate_scalars(this, modelname)
-! ******************************************************************************
-! allocate_scalars
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(BaseModelType) :: this
     character(len=*), intent(in) :: modelname
-! ------------------------------------------------------------------------------
     !
     call mem_allocate(this%name, LENMODELNAME, 'NAME', this%memoryPath)
     call mem_allocate(this%macronym, 3, 'MACRONYM', this%memoryPath)
@@ -183,23 +120,15 @@ subroutine allocate_scalars(this, modelname)
     this%iprflow = 0
     this%ipakcb = 0
     this%inewton = 0 !default is standard formulation
-    !
-    ! -- return
-    return
   end subroutine allocate_scalars
 
+  !> @brief Deallocate
+  !<
   subroutine model_da(this)
-! ******************************************************************************
-! deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(BaseModelType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Strings
     call mem_deallocate(this%name, 'NAME', this%memoryPath)
@@ -213,13 +142,9 @@ subroutine model_da(this)
     call mem_deallocate(this%iprflow)
     call mem_deallocate(this%ipakcb)
     call mem_deallocate(this%idsoln)
-    !
-    ! -- return
-    return
   end subroutine model_da
 
   function CastAsBaseModelClass(obj) result(res)
-    implicit none
     class(*), pointer, intent(inout) :: obj
     class(BaseModelType), pointer :: res
     !
@@ -230,11 +155,9 @@ function CastAsBaseModelClass(obj) result(res)
     class is (BaseModelType)
       res => obj
     end select
-    return
   end function CastAsBaseModelClass
 
   subroutine AddBaseModelToList(list, model)
-    implicit none
     ! -- dummy
     type(ListType), intent(inout) :: list
     class(BaseModelType), pointer, intent(inout) :: model
@@ -243,12 +166,9 @@ subroutine AddBaseModelToList(list, model)
     !
     obj => model
     call list%Add(obj)
-    !
-    return
   end subroutine AddBaseModelToList
 
   function GetBaseModelFromList(list, idx) result(res)
-    implicit none
     ! -- dummy
     type(ListType), intent(inout) :: list
     integer(I4B), intent(in) :: idx
@@ -258,8 +178,6 @@ function GetBaseModelFromList(list, idx) result(res)
     !
     obj => list%GetItem(idx)
     res => CastAsBaseModelClass(obj)
-    !
-    return
   end function GetBaseModelFromList
 
 end module BaseModelModule
diff --git a/src/Model/Connection/ConnectionBuilder.f90 b/src/Model/Connection/ConnectionBuilder.f90
index 4cf244cc59b..c7b6d28b8d6 100644
--- a/src/Model/Connection/ConnectionBuilder.f90
+++ b/src/Model/Connection/ConnectionBuilder.f90
@@ -2,7 +2,7 @@ module ConnectionBuilderModule
   use KindModule, only: I4B, LGP
   use SimModule, only: store_error, count_errors, ustop
   use SimVariablesModule, only: iout
-  use ListModule, only: ListType, arePointersEqual, isEqualIface, ListNodeType
+  use ListModule, only: ListType, isEqualIface, ListNodeType
   use BaseSolutionModule, only: BaseSolutionType
   use NumericalSolutionModule, only: NumericalSolutionType
   use BaseExchangeModule, only: BaseExchangeType, GetBaseExchangeFromList
@@ -18,6 +18,7 @@ module ConnectionBuilderModule
   private
 
   type, public :: ConnectionBuilderType
+    logical(LGP) :: dev_always_ifmod = .false. !< development option: force interface model on all exchanges
   contains
     procedure, pass(this) :: processSolution
     procedure, private, pass(this) :: processExchanges
@@ -78,7 +79,6 @@ end subroutine processSolution
   !<
   subroutine processExchanges(this, exchanges, newConnections)
     use ListsModule, only: baseconnectionlist, baseexchangelist
-    use VersionModule, only: IDEVELOPMODE
     class(ConnectionBuilderType) :: this !< the connection builder object
     type(ListType), pointer, intent(in) :: exchanges !< the list of exchanges to process
     type(ListType), intent(inout) :: newConnections !< the newly created connections
@@ -88,32 +88,18 @@ subroutine processExchanges(this, exchanges, newConnections)
     integer(I4B) :: iex, ibasex
     class(SpatialModelConnectionType), pointer :: modelConnection
     logical(LGP) :: isPeriodic
-    integer(I4B) :: status
-    logical(LGP) :: dev_always_ifmod
-    character(len=16) :: envvar
-
-    ! Force use of the interface model
-    dev_always_ifmod = .false.
-    if (IDEVELOPMODE == 1) then
-      call get_environment_variable('DEV_ALWAYS_USE_IFMOD', &
-                                    value=envvar, status=status)
-      if (status == 0 .and. envvar == '1') then
-        dev_always_ifmod = .true.
-        write (*, '(a,/)') "### Experimental: forcing interface model ###"
-      end if
-    end if
 
     do iex = 1, exchanges%Count()
       conEx => GetDisConnExchangeFromList(exchanges, iex)
       if (.not. associated(conEx)) then
         ! if it is not DisConnExchangeType, we can skip it
-        continue
+        cycle
       end if
 
       ! for now, if we have XT3D on the interface, we use a connection,
       ! (this will be more generic in the future)
       if (conEx%use_interface_model() .or. conEx%dev_ifmod_on &
-          .or. dev_always_ifmod) then
+          .or. this%dev_always_ifmod) then
 
         ! we should not get period connections here
         isPeriodic = (conEx%v_model1 == conEx%v_model2)
diff --git a/src/Model/Connection/GridConnection.f90 b/src/Model/Connection/GridConnection.f90
index 4530aee1df5..03a61f5ae3d 100644
--- a/src/Model/Connection/GridConnection.f90
+++ b/src/Model/Connection/GridConnection.f90
@@ -9,7 +9,7 @@ module GridConnectionModule
   use CharacterStringModule
   use MemoryManagerModule, only: mem_allocate, mem_deallocate
   use MemoryHelperModule, only: create_mem_path
-  use ListModule, only: ListType, isEqualIface, arePointersEqual
+  use ListModule, only: ListType, isEqualIface
   use NumericalModelModule
   use GwfDisuModule
   use DisConnExchangeModule
@@ -218,11 +218,9 @@ subroutine addToRegionalModels(this, v_model)
     class(VirtualModelType), pointer :: v_model !< the model to add to the region
     ! local
     class(*), pointer :: vm_obj
-    procedure(isEqualIface), pointer :: areEqualMethod
 
     vm_obj => v_model
-    areEqualMethod => arePointersEqual
-    if (.not. this%regionalModels%ContainsObject(vm_obj, areEqualMethod)) then
+    if (.not. this%regionalModels%ContainsObject(vm_obj)) then
       call this%regionalModels%Add(vm_obj)
     end if
 
@@ -1058,9 +1056,7 @@ subroutine buildInterfaceMap(this)
     ! first get the participating models
     call model_ids%init()
     do i = 1, this%nrOfCells
-      if (.not. model_ids%contains(this%idxToGlobal(i)%v_model%id)) then
-        call model_ids%push_back(this%idxToGlobal(i)%v_model%id)
-      end if
+      call model_ids%push_back_unique(this%idxToGlobal(i)%v_model%id)
     end do
 
     ! initialize the map
diff --git a/src/Model/Connection/GridSorting.f90 b/src/Model/Connection/GridSorting.f90
index 3360b62809d..5d15fa2382c 100644
--- a/src/Model/Connection/GridSorting.f90
+++ b/src/Model/Connection/GridSorting.f90
@@ -2,7 +2,7 @@ module GridSorting
   use KindModule, only: I4B, DP, LGP
   use ConstantsModule, only: DHALF
   use CellWithNbrsModule, only: GlobalCellType
-  use GenericUtilitiesModule, only: is_same
+  use MathUtilModule, only: is_close
   use BaseDisModule, only: dis_transform_xy
   implicit none
   private
@@ -75,11 +75,11 @@ function lessThan(n, m) result(isLess)
                     dis_bot_m(gcm%index))
 
       ! compare
-      if (.not. is_same(zn, zm, 10 * epsilon(zn))) then
+      if (.not. is_close(zn, zm, 10 * epsilon(zn))) then
         isLess = zn > zm
-      else if (.not. is_same(yn, ym, 10 * epsilon(yn))) then
+      else if (.not. is_close(yn, ym, 10 * epsilon(yn))) then
         isLess = yn > ym
-      else if (.not. is_same(xn, xm, 10 * epsilon(xn))) then
+      else if (.not. is_close(xn, xm, 10 * epsilon(xn))) then
         isLess = xn < xm
       else
         isLess = .false.
diff --git a/src/Model/Connection/GwfGwfConnection.f90 b/src/Model/Connection/GwfGwfConnection.f90
index 52e089e6aee..625c41d8525 100644
--- a/src/Model/Connection/GwfGwfConnection.f90
+++ b/src/Model/Connection/GwfGwfConnection.f90
@@ -37,10 +37,9 @@ module GwfGwfConnectionModule
   !<
   type, public, extends(SpatialModelConnectionType) :: GwfGwfConnectionType
 
-    type(GwfModelType), pointer :: gwfModel => null() !< the model for which this connection exists
-    type(GwfExchangeType), pointer :: gwfExchange => null() !< the primary exchange, cast to its concrete type
-    logical(LGP) :: owns_exchange !< when true, this connection has ownership over the exchange (memory)
-    type(GwfInterfaceModelType), pointer :: gwfInterfaceModel => null() !< the interface model
+    class(GwfModelType), pointer :: gwfModel => null() !< the model for which this connection exists
+    class(GwfExchangeType), pointer :: gwfExchange => null() !< the primary exchange, cast to its concrete type
+    class(GwfInterfaceModelType), pointer :: gwfInterfaceModel => null() !< the interface model
     integer(I4B), pointer :: iXt3dOnExchange => null() !< run XT3D on the interface,
                                                        !! 0 = don't, 1 = matrix, 2 = rhs
     integer(I4B) :: iout = 0 !< the list file for the interface model
@@ -70,6 +69,7 @@ module GwfGwfConnectionModule
     procedure, private :: setGridExtent
     procedure, private :: validateGwfExchange
     procedure, private :: setFlowToExchange
+    procedure, private :: setFlowToModel
     procedure, private :: setNpfEdgeProps
 
   end type GwfGwfConnectionType
@@ -226,6 +226,9 @@ subroutine cfg_dist_vars(this)
     call this%cfg_dv('TOP', 'DIS', SYNC_NDS, (/STG_BFR_CON_AR/))
     call this%cfg_dv('BOT', 'DIS', SYNC_NDS, (/STG_BFR_CON_AR/))
     call this%cfg_dv('AREA', 'DIS', SYNC_NDS, (/STG_BFR_CON_AR/))
+    if (this%gwfInterfaceModel%inbuy > 0) then
+      call this%cfg_dv('DENSE', 'BUY', SYNC_NDS, (/STG_BFR_EXG_CF/))
+    end if
 
   end subroutine cfg_dist_vars
 
@@ -305,7 +308,7 @@ subroutine gwfgwfcon_ad(this)
     class(GwfGwfConnectionType) :: this !< this connection
 
     ! this triggers the BUY density calculation
-    if (this%gwfInterfaceModel%inbuy > 0) call this%gwfInterfaceModel%buy%buy_ad()
+    !if (this%gwfInterfaceModel%inbuy > 0) call this%gwfInterfaceModel%buy%buy_ad()
 
     if (this%owns_exchange) then
       call this%gwfExchange%exg_ad()
@@ -313,23 +316,18 @@ subroutine gwfgwfcon_ad(this)
 
   end subroutine gwfgwfcon_ad
 
-  !> @brief Calculate (or adjust) matrix coefficients,
-  !! in this case those which are determined or affected
-  !< by the connection of a GWF model with its neigbors
   subroutine gwfgwfcon_cf(this, kiter)
     class(GwfGwfConnectionType) :: this !< this connection
     integer(I4B), intent(in) :: kiter !< the iteration counter
-    ! local
-    integer(I4B) :: i
 
-    ! reset interface system
-    call this%matrix%zero_entries()
-    do i = 1, this%neq
-      this%rhs(i) = 0.0_DP
-    end do
+    call this%SpatialModelConnectionType%spatialcon_cf(kiter)
 
-    ! calculate (wetting/drying, saturation)
-    call this%gwfInterfaceModel%model_cf(kiter)
+    ! CF the movers through the exchange
+    if (this%owns_exchange) then
+      if (this%gwfExchange%inmvr > 0) then
+        call this%gwfExchange%mvr%xmvr_cf()
+      end if
+    end if
 
   end subroutine gwfgwfcon_cf
 
@@ -342,36 +340,9 @@ subroutine gwfgwfcon_fc(this, kiter, matrix_sln, rhs_sln, inwtflag)
     real(DP), dimension(:), intent(inout) :: rhs_sln !< global right-hand-side
     integer(I4B), optional, intent(in) :: inwtflag !< newton-raphson flag
     ! local
-    integer(I4B) :: n, nglo
-    integer(I4B) :: ipos, icol_start, icol_end
-    class(MatrixBaseType), pointer :: matrix_base
 
-    ! fill (and add to...) coefficients for interface
-    matrix_base => this%matrix
-    call this%gwfInterfaceModel%model_fc(kiter, matrix_base, inwtflag)
-
-    ! map back to solution matrix
-    do n = 1, this%neq
-      ! we cannot check with the mask here, because cross-terms are not
-      ! necessarily from primary connections. But, we only need the coefficients
-      ! for our own model (i.e. fluxes into cells belonging to this%owner):
-      if (.not. this%ig_builder%idxToGlobal(n)%v_model == this%owner) then
-        ! only add connections for own model to global matrix
-        cycle
-      end if
-
-      nglo = this%ig_builder%idxToGlobal(n)%index + &
-             this%ig_builder%idxToGlobal(n)%v_model%moffset%get() - &
-             matrix_sln%get_row_offset()
-      rhs_sln(nglo) = rhs_sln(nglo) + this%rhs(n)
-
-      icol_start = this%matrix%get_first_col_pos(n)
-      icol_end = this%matrix%get_last_col_pos(n)
-      do ipos = icol_start, icol_end
-        call matrix_sln%add_value_pos(this%ipos_to_sln(ipos), &
-                                      this%matrix%get_value_pos(ipos))
-      end do
-    end do
+    call this%SpatialModelConnectionType%spatialcon_fc( &
+      kiter, matrix_sln, rhs_sln, inwtflag)
 
     ! FC the movers through the exchange; we cannot call
     ! exg_fc() directly because it calculates matrix terms
@@ -394,9 +365,8 @@ subroutine validateConnection(this)
     ! local
 
     ! base validation (geometry/spatial)
-    ! TODO_MJR: uncomment this...
-    !call this%SpatialModelConnectionType%validateConnection()
-    !call this%validateGwfExchange()
+    call this%SpatialModelConnectionType%validateConnection()
+    call this%validateGwfExchange()
 
     ! abort on errors
     if (count_errors() > 0) then
@@ -426,6 +396,11 @@ subroutine validateGwfExchange(this)
     logical(LGP) :: compatible
 
     gwfEx => this%gwfExchange
+
+    ! we cannot validate this (yet) in parallel mode
+    if (.not. gwfEx%v_model1%is_local) return
+    if (.not. gwfEx%v_model2%is_local) return
+
     modelPtr => this%gwfExchange%model1
     gwfModel1 => CastAsGwfModel(modelPtr)
     modelPtr => this%gwfExchange%model2
@@ -527,6 +502,8 @@ subroutine gwfgwfcon_cq(this, icnvg, isuppress_output, isolnid)
 
     call this%setFlowToExchange()
 
+    call this%setFlowToModel()
+
     !cdl Could we allow GwfExchange to do this instead, using
     !    simvals?
     ! if needed, we add the edge properties to the model's NPF
@@ -569,13 +546,54 @@ subroutine setFlowToExchange(this)
 
   end subroutine setFlowToExchange
 
+  !> @brief Set the flows (flowja from the interface model) to
+  !< to the model, update the budget
+  subroutine setFlowToModel(this)
+    class(GwfGwfConnectionType) :: this !< this connection
+    ! local
+    integer(I4B) :: n, m, ipos, iposLoc
+    integer(I4B) :: nLoc, mLoc
+    type(ConnectionsType), pointer :: imCon !< interface model connections
+    type(GlobalCellType), dimension(:), pointer :: toGlobal !< map interface index to global cell
+
+    ! for readability
+    imCon => this%gwfInterfaceModel%dis%con
+    toGlobal => this%ig_builder%idxToGlobal
+
+    do n = 1, this%neq
+      if (.not. toGlobal(n)%v_model == this%owner) then
+        ! only add flows to own model
+        cycle
+      end if
+
+      nLoc = toGlobal(n)%index
+
+      do ipos = imCon%ia(n) + 1, imCon%ia(n + 1) - 1
+        if (imCon%mask(ipos) < 1) cycle ! skip this connection, it's masked so not determined by us
+
+        m = imCon%ja(ipos)
+        mLoc = toGlobal(m)%index
+        if (toGlobal(m)%v_model == this%owner) then
+
+          ! internal, need to set flowja for n-m
+          iposLoc = getCSRIndex(nLoc, mLoc, this%gwfModel%ia, this%gwfModel%ja)
+
+          ! update flowja with correct value
+          this%gwfModel%flowja(iposLoc) = this%gwfInterfaceModel%flowja(ipos)
+
+        end if
+      end do
+    end do
+
+  end subroutine setFlowToModel
+
   !> @brief Set flowja as edge properties in the model,
   !< so it can be used for e.g. specific discharge calculation
   subroutine setNpfEdgeProps(this)
     class(GwfGwfConnectionType) :: this !< this connection
     ! local
     integer(I4B) :: n, m, ipos, isym
-    integer(I4B) :: nLoc, mLoc, iposLoc
+    integer(I4B) :: nLoc, mLoc
     integer(I4B) :: ihc
     real(DP) :: rrate
     real(DP) :: area
@@ -648,12 +666,6 @@ subroutine setNpfEdgeProps(this)
           dist = conLen * cl / (imCon%cl1(isym) + imCon%cl2(isym))
           call this%gwfModel%npf%set_edge_properties(nLoc, ihc, rrate, area, &
                                                      nx, ny, dist)
-        else
-          ! internal, need to set flowja for n-m
-          iposLoc = getCSRIndex(nLoc, mLoc, this%gwfModel%ia, this%gwfModel%ja)
-
-          ! update flowja with correct value
-          this%gwfModel%flowja(iposLoc) = this%gwfInterfaceModel%flowja(ipos)
         end if
       end do
     end do
diff --git a/src/Model/Connection/GwtGwtConnection.f90 b/src/Model/Connection/GwtGwtConnection.f90
index 8c7df985c50..0f8ea2eb798 100644
--- a/src/Model/Connection/GwtGwtConnection.f90
+++ b/src/Model/Connection/GwtGwtConnection.f90
@@ -28,11 +28,9 @@ module GwtGwtConnectionModule
   !<
   type, public, extends(SpatialModelConnectionType) :: GwtGwtConnectionType
 
-    type(GwtModelType), pointer :: gwtModel => null() !< the model for which this connection exists
-    type(GwtExchangeType), pointer :: gwtExchange => null() !< the primary exchange, cast to GWT-GWT
-    logical(LGP) :: exchangeIsOwned !< there are two connections (in serial) for an exchange,
-                                    !! one of them needs to manage/own the exchange (e.g. clean up)
-    type(GwtInterfaceModelType), pointer :: gwtInterfaceModel => null() !< the interface model
+    class(GwtModelType), pointer :: gwtModel => null() !< the model for which this connection exists
+    class(GwtExchangeType), pointer :: gwtExchange => null() !< the primary exchange, cast to GWT-GWT
+    class(GwtInterfaceModelType), pointer :: gwtInterfaceModel => null() !< the interface model
     integer(I4B), pointer :: iIfaceAdvScheme => null() !< the advection scheme at the interface:
                                                        !! 0 = upstream, 1 = central, 2 = TVD
     integer(I4B), pointer :: iIfaceXt3d => null() !< XT3D in the interface DSP package: 0 = no, 1 = lhs, 2 = rhs
@@ -57,10 +55,8 @@ module GwtGwtConnectionModule
 
     procedure :: exg_ar => gwtgwtcon_ar
     procedure :: exg_df => gwtgwtcon_df
-    procedure :: exg_ac => gwtgwtcon_ac
     procedure :: exg_rp => gwtgwtcon_rp
     procedure :: exg_ad => gwtgwtcon_ad
-    procedure :: exg_cf => gwtgwtcon_cf
     procedure :: exg_fc => gwtgwtcon_fc
     procedure :: exg_da => gwtgwtcon_da
     procedure :: exg_cq => gwtgwtcon_cq
@@ -100,9 +96,13 @@ subroutine gwtGwtConnection_ctor(this, model, gwtEx)
     objPtr => gwtEx
     this%gwtExchange => CastAsGwtExchange(objPtr)
 
-    this%exchangeIsOwned = associated(model, gwtEx%model1)
+    if (gwtEx%v_model1%is_local .and. gwtEx%v_model2%is_local) then
+      this%owns_exchange = associated(model, gwtEx%model1)
+    else
+      this%owns_exchange = .true.
+    end if
 
-    if (this%exchangeIsOwned) then
+    if (gwtEx%v_model1 == model) then
       write (name, '(a,i0)') 'GWTCON1_', gwtEx%id
     else
       write (name, '(a,i0)') 'GWTCON2_', gwtEx%id
@@ -125,7 +125,7 @@ subroutine gwtGwtConnection_ctor(this, model, gwtEx)
     call this%allocate_scalars()
     this%typename = 'GWT-GWT'
     this%iIfaceAdvScheme = 0
-    this%iIfaceXt3d = 1
+    this%iIfaceXt3d = 0
     this%exgflowSign = 1
 
     allocate (this%gwtInterfaceModel)
@@ -155,9 +155,14 @@ subroutine gwtgwtcon_df(this)
     ! has been read at this point)
     this%iIfaceAdvScheme = this%gwtExchange%iAdvScheme
 
-    ! determine xt3d setting on interface
+    ! determine xt3d setting on interface- (TODO_MJR: default is on?)
     this%iIfaceXt3d = this%gwtExchange%ixt3d
 
+    ! turn off when off in the owning model
+    if (this%gwtModel%indsp > 0) then
+      this%iIfaceXt3d = this%gwtModel%dsp%ixt3d
+    end if
+
     ! determine the required size of the interface model grid
     call this%setGridExtent()
 
@@ -166,7 +171,7 @@ subroutine gwtgwtcon_df(this)
 
     ! we have to 'catch up' and create the interface model
     ! here, then the remainder of this routine will be define
-    if (this%exchangeIsOwned) then
+    if (this%prim_exchange%v_model1 == this%owner) then
       write (imName, '(a,i0)') 'GWTIM1_', this%gwtExchange%id
     else
       write (imName, '(a,i0)') 'GWTIM2_', this%gwtExchange%id
@@ -287,7 +292,7 @@ subroutine gwtgwtcon_ar(this)
     call this%gwtInterfaceModel%model_ar()
 
     ! AR the movers and obs through the exchange
-    if (this%exchangeIsOwned) then
+    if (this%owns_exchange) then
       !cdl implement this when MVT is ready
       !cdl if (this%gwtExchange%inmvt > 0) then
       !cdl   call this%gwtExchange%mvt%mvt_ar()
@@ -309,6 +314,10 @@ subroutine validateConnection(this)
     ! base validation, the spatial/geometry part
     call this%SpatialModelConnectionType%validateConnection()
 
+    ! we cannot validate this (yet) in parallel mode
+    if (.not. this%gwtExchange%v_model1%is_local) return
+    if (.not. this%gwtExchange%v_model2%is_local) return
+
     ! GWT related matters
     if ((this%gwtExchange%gwtmodel1%inadv > 0 .and. &
          this%gwtExchange%gwtmodel2%inadv == 0) .or. &
@@ -338,35 +347,11 @@ subroutine validateConnection(this)
 
   end subroutine validateConnection
 
-  !> @brief add connections to the global system for
-  !< this connection
-  subroutine gwtgwtcon_ac(this, sparse)
-    class(GwtGwtConnectionType) :: this !< this connection
-    type(sparsematrix), intent(inout) :: sparse !< sparse matrix to store the connections
-    ! local
-    integer(I4B) :: ic, iglo, jglo
-    type(GlobalCellType) :: boundaryCell, connectedCell
-
-    ! connections to other models
-    do ic = 1, this%ig_builder%nrOfBoundaryCells
-      boundaryCell = this%ig_builder%boundaryCells(ic)%cell
-      connectedCell = this%ig_builder%connectedCells(ic)%cell
-      iglo = boundaryCell%index + boundaryCell%v_model%moffset%get()
-      jglo = connectedCell%index + connectedCell%v_model%moffset%get()
-      call sparse%addconnection(iglo, jglo, 1)
-      call sparse%addconnection(jglo, iglo, 1)
-    end do
-
-    ! and internal connections
-    call this%spatialcon_ac(sparse)
-
-  end subroutine gwtgwtcon_ac
-
   subroutine gwtgwtcon_rp(this)
     class(GwtGwtConnectionType) :: this !< the connection
 
     ! Call exchange rp routines
-    if (this%exchangeIsOwned) then
+    if (this%owns_exchange) then
       call this%gwtExchange%exg_rp()
     end if
 
@@ -380,28 +365,12 @@ subroutine gwtgwtcon_ad(this)
     ! recalculate dispersion ellipse
     if (this%gwtInterfaceModel%indsp > 0) call this%gwtInterfaceModel%dsp%dsp_ad()
 
-    if (this%exchangeIsOwned) then
+    if (this%owns_exchange) then
       call this%gwtExchange%exg_ad()
     end if
 
   end subroutine gwtgwtcon_ad
 
-  subroutine gwtgwtcon_cf(this, kiter)
-    class(GwtGwtConnectionType) :: this !< the connection
-    integer(I4B), intent(in) :: kiter !< the iteration counter
-    ! local
-    integer(I4B) :: i
-
-    ! reset interface system
-    call this%matrix%zero_entries()
-    do i = 1, this%neq
-      this%rhs(i) = 0.0_DP
-    end do
-
-    call this%gwtInterfaceModel%model_cf(kiter)
-
-  end subroutine gwtgwtcon_cf
-
   subroutine gwtgwtcon_fc(this, kiter, matrix_sln, rhs_sln, inwtflag)
     class(GwtGwtConnectionType) :: this !< the connection
     integer(I4B), intent(in) :: kiter !< the iteration counter
@@ -409,37 +378,16 @@ subroutine gwtgwtcon_fc(this, kiter, matrix_sln, rhs_sln, inwtflag)
     real(DP), dimension(:), intent(inout) :: rhs_sln !< global right-hand-side
     integer(I4B), optional, intent(in) :: inwtflag !< newton-raphson flag
     ! local
-    integer(I4B) :: n, nglo
-    integer(I4B) :: icol_start, icol_end, ipos
-    class(MatrixBaseType), pointer :: matrix_base
-
-    matrix_base => this%matrix
-    call this%gwtInterfaceModel%model_fc(kiter, matrix_base, inwtflag)
-
-    ! map back to solution matrix
-    do n = 1, this%neq
-      ! We only need the coefficients for our own model
-      ! (i.e. rows in the matrix that belong to this%owner):
-      if (.not. this%ig_builder%idxToGlobal(n)%v_model == this%owner) then
-        cycle
-      end if
 
-      nglo = this%ig_builder%idxToGlobal(n)%index + &
-             this%ig_builder%idxToGlobal(n)%v_model%moffset%get()
-      rhs_sln(nglo) = rhs_sln(nglo) + this%rhs(n)
+    call this%SpatialModelConnectionType%spatialcon_fc( &
+      kiter, matrix_sln, rhs_sln, inwtflag)
 
-      icol_start = this%matrix%get_first_col_pos(n)
-      icol_end = this%matrix%get_last_col_pos(n)
-      do ipos = icol_start, icol_end
-        call matrix_sln%add_value_pos(this%ipos_to_sln(ipos), &
-                                      this%matrix%get_value_pos(ipos))
-      end do
-    end do
-
-    ! FC the movers through the exchange; we can call
-    ! exg_fc() directly because it only handles mover terms (unlike in GwfExchange%exg_fc)
-    if (this%exchangeIsOwned) then
-      call this%gwtExchange%exg_fc(kiter, matrix_sln, rhs_sln, inwtflag)
+    ! FC the movers through the exchange
+    if (this%owns_exchange) then
+      if (this%gwtExchange%inmvt > 0) then
+        call this%gwtExchange%mvt%mvt_fc(this%gwtExchange%gwtmodel1%x, &
+                                         this%gwtExchange%gwtmodel2%x)
+      end if
     end if
 
   end subroutine gwtgwtcon_fc
@@ -465,7 +413,7 @@ subroutine setFlowToExchange(this)
     class(GwtExchangeType), pointer :: gwtEx
     type(IndexMapSgnType), pointer :: map
 
-    if (this%exchangeIsOwned) then
+    if (this%owns_exchange) then
       gwtEx => this%gwtExchange
       map => this%interface_map%exchange_maps(this%interface_map%prim_exg_idx)
 
@@ -488,7 +436,7 @@ subroutine gwtgwtcon_bd(this, icnvg, isuppress_output, isolnid)
 
     ! call exchange budget routine, also calls bd
     ! for movers.
-    if (this%exchangeIsOwned) then
+    if (this%owns_exchange) then
       call this%gwtExchange%exg_bd(icnvg, isuppress_output, isolnid)
     end if
 
@@ -500,7 +448,7 @@ subroutine gwtgwtcon_ot(this)
     ! Call exg_ot() here as it handles all output processing
     ! based on gwtExchange%simvals(:), which was correctly
     ! filled from gwtgwtcon
-    if (this%exchangeIsOwned) then
+    if (this%owns_exchange) then
       call this%gwtExchange%exg_ot()
     end if
 
@@ -532,7 +480,7 @@ subroutine gwtgwtcon_da(this)
     end if
 
     ! we need to deallocate the exchange we own:
-    if (this%exchangeIsOwned) then
+    if (this%owns_exchange) then
       call this%gwtExchange%exg_da()
     end if
 
diff --git a/src/Model/Connection/GwtInterfaceModel.f90 b/src/Model/Connection/GwtInterfaceModel.f90
index 43c1d25865c..4adfda4c36d 100644
--- a/src/Model/Connection/GwtInterfaceModel.f90
+++ b/src/Model/Connection/GwtInterfaceModel.f90
@@ -1,17 +1,18 @@
 module GwtInterfaceModelModule
   use KindModule, only: I4B, DP
+  use ConstantsModule, only: DONE
   use MemoryManagerModule, only: mem_allocate, mem_deallocate, mem_reallocate
   use MemoryHelperModule, only: create_mem_path
   use NumericalModelModule, only: NumericalModelType
   use GwtModule, only: GwtModelType, CastAsGwtModel
   use GwfDisuModule, only: disu_cr, CastAsDisuType
-  use GwtFmiModule, only: fmi_cr, GwtFmiType
-  use GwtAdvModule, only: adv_cr, GwtAdvType
-  use GwtAdvOptionsModule, only: GwtAdvOptionsType
+  use TspFmiModule, only: fmi_cr, TspFmiType
+  use TspAdvModule, only: adv_cr, TspAdvType
+  use TspAdvOptionsModule, only: TspAdvOptionsType
   use GwtDspModule, only: dsp_cr, GwtDspType
   use GwtDspOptionsModule, only: GwtDspOptionsType
   use GwtMstModule, only: mst_cr
-  use GwtObsModule, only: gwt_obs_cr
+  use TspObsModule, only: tsp_obs_cr
   use GridConnectionModule
 
   implicit none
@@ -25,6 +26,7 @@ module GwtInterfaceModelModule
 
     integer(i4B), pointer :: iAdvScheme => null() !< the advection scheme: 0 = up, 1 = central, 2 = tvd
     integer(i4B), pointer :: ixt3d => null() !< xt3d setting: 0 = off, 1 = lhs, 2 = rhs
+    real(DP), pointer :: ieqnsclfac => null() !< governing eqn scaling factor: 1: GWT, >1: GWE
 
     class(GridConnectionType), pointer :: gridConnection => null() !< The grid connection class will provide the interface grid
     class(GwtModelType), private, pointer :: owner => null() !< the real GWT model for which the exchange coefficients
@@ -59,6 +61,7 @@ subroutine gwtifmod_cr(this, name, iout, gridConn)
     ! defaults
     this%iAdvScheme = 0
     this%ixt3d = 0
+    this%ieqnsclfac = DONE
 
     this%iout = iout
     this%gridConnection => gridConn
@@ -79,10 +82,12 @@ subroutine gwtifmod_cr(this, name, iout, gridConn)
 
     ! create dis and packages
     call disu_cr(this%dis, this%name, '', -1, this%iout)
-    call fmi_cr(this%fmi, this%name, 0, this%iout)
-    call adv_cr(this%adv, this%name, adv_unit, this%iout, this%fmi)
+    call fmi_cr(this%fmi, this%name, 0, this%iout, this%ieqnsclfac, &
+                this%depvartype)
+    call adv_cr(this%adv, this%name, adv_unit, this%iout, this%fmi, &
+                this%ieqnsclfac)
     call dsp_cr(this%dsp, this%name, '', -dsp_unit, this%iout, this%fmi)
-    call gwt_obs_cr(this%obs, inobs)
+    call tsp_obs_cr(this%obs, inobs)
 
   end subroutine gwtifmod_cr
 
@@ -94,6 +99,7 @@ subroutine allocate_scalars(this, modelname)
 
     call mem_allocate(this%iAdvScheme, 'ADVSCHEME', this%memoryPath)
     call mem_allocate(this%ixt3d, 'IXT3D', this%memoryPath)
+    call mem_allocate(this%ieqnsclfac, 'IEQNSCLFAC', this%memoryPath)
 
   end subroutine allocate_scalars
 
@@ -117,7 +123,7 @@ subroutine gwtifmod_df(this)
     class(GwtInterfaceModelType) :: this !< the GWT interface model
     ! local
     class(*), pointer :: disPtr
-    type(GwtAdvOptionsType) :: adv_options
+    type(TspAdvOptionsType) :: adv_options
     type(GwtDspOptionsType) :: dsp_options
 
     this%moffset = 0
@@ -127,7 +133,7 @@ subroutine gwtifmod_df(this)
     ! define DISU
     disPtr => this%dis
     call this%gridConnection%getDiscretization(CastAsDisuType(disPtr))
-    call this%fmi%fmi_df(this%dis, 0)
+    call this%fmi%fmi_df(this%dis)
 
     if (this%inadv > 0) then
       call this%adv%adv_df(adv_options)
@@ -192,6 +198,7 @@ subroutine gwtifmod_da(this)
     ! this
     call mem_deallocate(this%iAdvScheme)
     call mem_deallocate(this%ixt3d)
+    call mem_deallocate(this%ieqnsclfac)
 
     ! gwt packages
     call this%dis%dis_da()
@@ -219,6 +226,7 @@ subroutine gwtifmod_da(this)
     call mem_deallocate(this%inmvt)
     call mem_deallocate(this%inoc)
     call mem_deallocate(this%inobs)
+    call mem_deallocate(this%eqnsclfac)
 
     ! base
     call this%NumericalModelType%model_da()
diff --git a/src/Model/Connection/SpatialModelConnection.f90 b/src/Model/Connection/SpatialModelConnection.f90
index a383d608414..6ebc92fef6c 100644
--- a/src/Model/Connection/SpatialModelConnection.f90
+++ b/src/Model/Connection/SpatialModelConnection.f90
@@ -41,6 +41,8 @@ module SpatialModelConnectionModule
     integer(I4B), pointer :: nr_connections => null() !< total nr. of connected cells (primary)
 
     class(DisConnExchangeType), pointer :: prim_exchange => null() !< the exchange for which the interface model is created
+    logical(LGP) :: owns_exchange !< there are two connections (in serial) for an exchange,
+                                  !! one of them needs to manage/own the exchange (e.g. clean up)
     type(STLVecInt), pointer :: halo_models !< models that are potentially in the halo of this interface
     type(STLVecInt), pointer :: halo_exchanges !< exchanges that are potentially part of the halo of this interface (includes primary)
     integer(I4B), pointer :: int_stencil_depth => null() !< size of the computational stencil for the interior
@@ -72,12 +74,16 @@ module SpatialModelConnectionModule
     procedure :: exg_ar => spatialcon_ar
     procedure :: exg_ac => spatialcon_ac
     procedure :: exg_mc => spatialcon_mc
+    procedure :: exg_cf => spatialcon_cf
+    procedure :: exg_fc => spatialcon_fc
     procedure :: exg_da => spatialcon_da
 
     ! protected
     procedure, pass(this) :: spatialcon_df
     procedure, pass(this) :: spatialcon_ar
     procedure, pass(this) :: spatialcon_ac
+    procedure, pass(this) :: spatialcon_cf
+    procedure, pass(this) :: spatialcon_fc
     procedure, pass(this) :: spatialcon_da
     procedure, pass(this) :: spatialcon_setmodelptrs
     procedure, pass(this) :: spatialcon_connect
@@ -344,11 +350,10 @@ subroutine maskOwnerConnections(this)
           if (this%owner%dis%con%mask(csr_idx) > 0) then
             call this%owner%dis%con%set_mask(csr_idx, 0)
           else
-            ! edge case, someone will be calculating this connection
-            ! so we ignore it here
-            write (*, *) 'Warning: overlap detected, no mask on connection ', &
-              nloc, ':', mloc, ' in model ', trim(this%owner%name), &
-              ' for Exchange ', trim(this%prim_exchange%name)
+            ! edge case, this connection is already being calculated
+            ! so we ignore it here. This can happen in the overlap
+            ! between two different exchanges when a larger stencil
+            ! (XT3D) is applied.
             call conn%set_mask(ipos, 0)
           end if
         end if
@@ -429,6 +434,65 @@ subroutine spatialcon_mc(this, matrix_sln)
 
   end subroutine spatialcon_mc
 
+  !> @brief Calculate (or adjust) matrix coefficients,
+  !! in this case those which are determined or affected
+  !< by the connection of a GWF model with its neigbors
+  subroutine spatialcon_cf(this, kiter)
+    class(SpatialModelConnectionType) :: this !< this connection
+    integer(I4B), intent(in) :: kiter !< the iteration counter
+    ! local
+    integer(I4B) :: i
+
+    ! reset interface system
+    call this%matrix%zero_entries()
+    do i = 1, this%neq
+      this%rhs(i) = 0.0_DP
+    end do
+
+    ! calculate the interface model
+    call this%interface_model%model_cf(kiter)
+
+  end subroutine spatialcon_cf
+
+  !> @brief Formulate coefficients from interface model
+  !<
+  subroutine spatialcon_fc(this, kiter, matrix_sln, rhs_sln, inwtflag)
+    class(SpatialModelConnectionType) :: this !< this connection
+    integer(I4B), intent(in) :: kiter !< the iteration counter
+    class(MatrixBaseType), pointer :: matrix_sln !< the system matrix
+    real(DP), dimension(:), intent(inout) :: rhs_sln !< global right-hand-side
+    integer(I4B), optional, intent(in) :: inwtflag !< newton-raphson flag
+    ! local
+    integer(I4B) :: n, nglo
+    integer(I4B) :: icol_start, icol_end, ipos
+    class(MatrixBaseType), pointer :: matrix_base
+
+    matrix_base => this%matrix
+    call this%interface_model%model_fc(kiter, matrix_base, inwtflag)
+
+    ! map back to solution matrix
+    do n = 1, this%neq
+      ! We only need the coefficients for our own model
+      ! (i.e. rows in the matrix that belong to this%owner):
+      if (.not. this%ig_builder%idxToGlobal(n)%v_model == this%owner) then
+        cycle
+      end if
+
+      nglo = this%ig_builder%idxToGlobal(n)%index + &
+             this%ig_builder%idxToGlobal(n)%v_model%moffset%get() - &
+             matrix_sln%get_row_offset()
+      rhs_sln(nglo) = rhs_sln(nglo) + this%rhs(n)
+
+      icol_start = this%matrix%get_first_col_pos(n)
+      icol_end = this%matrix%get_last_col_pos(n)
+      do ipos = icol_start, icol_end
+        call matrix_sln%add_value_pos(this%ipos_to_sln(ipos), &
+                                      this%matrix%get_value_pos(ipos))
+      end do
+    end do
+
+  end subroutine spatialcon_fc
+
   !> @brief Deallocation
   !<
   subroutine spatialcon_da(this)
@@ -549,16 +613,16 @@ subroutine validateConnection(this)
     conEx => this%prim_exchange
     if (conEx%ixt3d > 0) then
       ! if XT3D, we need these angles:
-      if (conEx%model1%dis%con%ianglex == 0) then
+      if (conEx%v_model1%con_ianglex%get() == 0) then
         write (errmsg, '(a,a,a,a,a)') 'XT3D configured on the exchange ', &
           trim(conEx%name), ' but the discretization in model ', &
-          trim(conEx%model1%name), ' has no ANGLDEGX specified'
+          trim(conEx%v_model1%name), ' has no ANGLDEGX specified'
         call store_error(errmsg)
       end if
-      if (conEx%model2%dis%con%ianglex == 0) then
+      if (conEx%v_model2%con_ianglex%get() == 0) then
         write (errmsg, '(a,a,a,a,a)') 'XT3D configured on the exchange ', &
           trim(conEx%name), ' but the discretization in model ', &
-          trim(conEx%model2%name), ' has no ANGLDEGX specified'
+          trim(conEx%v_model2%name), ' has no ANGLDEGX specified'
         call store_error(errmsg)
       end if
     end if
diff --git a/src/Model/ExplicitModel.f90 b/src/Model/ExplicitModel.f90
index ae5630b83da..6c23d5a0969 100644
--- a/src/Model/ExplicitModel.f90
+++ b/src/Model/ExplicitModel.f90
@@ -1,18 +1,12 @@
-!> @brief Explicit Model Module
-!!
-!! This module contains the Explicit Model, which is a parent
-!! class for models that solve themselves.  Explicit models are
-!! added to an Explicit Solution, which is simply a container
-!! that scrolls through a list of explicit models and calls
-!! methods in a prescribed sequence.
-!!
-!<
+!> @brief Models that solve themselves
 module ExplicitModelModule
 
-  use KindModule, only: I4B
+  use KindModule, only: I4B, DP
+  use ConstantsModule, only: LINELENGTH
   use ListModule, only: ListType
   use BaseModelModule, only: BaseModelType
   use BaseDisModule, only: DisBaseType
+  use MemoryManagerModule, only: mem_allocate, mem_deallocate
 
   implicit none
   private
@@ -21,22 +15,27 @@ module ExplicitModelModule
             AddExplicitModelToList, &
             GetExplicitModelFromList
 
-  !> @brief Derived type for the Explicit Model Type
-  !!
-  !! This derived type describes a parent class for explicit
-  !! models.
+  !> @brief Base type for models that solve themselves.
   !!
+  !! An explicit solution simply scrolls through a list of explicit
+  !! models and calls solution procedures in a prescribed sequence.
   !<
   type, extends(BaseModelType) :: ExplicitModelType
-    type(ListType), pointer :: bndlist => null() !< array of boundary packages for this model
+    character(len=LINELENGTH), pointer :: filename => null() !< input file name
+    integer(I4B), dimension(:), pointer, contiguous :: ibound => null() !< ibound array
+    type(ListType), pointer :: bndlist => null() !< array of boundary packages
     class(DisBaseType), pointer :: dis => null() !< discretization object
   contains
+    ! -- Overridden methods
     procedure :: model_ad
     procedure :: model_solve
     procedure :: model_cq
     procedure :: model_bd
     procedure :: model_da
+    ! -- Utility methods
     procedure :: allocate_scalars
+    procedure :: allocate_arrays
+    procedure :: set_idsoln
   end type ExplicitModelType
 
 contains
@@ -45,18 +44,12 @@ module ExplicitModelModule
   !<
   subroutine model_ad(this)
     class(ExplicitModelType) :: this
-    !
-    ! -- return
-    return
   end subroutine model_ad
 
   !> @ brief Solve the model
   !<
   subroutine model_solve(this)
     class(ExplicitModelType) :: this
-    !
-    ! -- return
-    return
   end subroutine model_solve
 
   !> @ brief Calculate model flows
@@ -65,9 +58,6 @@ subroutine model_cq(this, icnvg, isuppress_output)
     class(ExplicitModelType) :: this
     integer(I4B), intent(in) :: icnvg
     integer(I4B), intent(in) :: isuppress_output
-    !
-    ! -- return
-    return
   end subroutine model_cq
 
   !> @ brief Calculate model budget
@@ -76,68 +66,68 @@ subroutine model_bd(this, icnvg, isuppress_output)
     class(ExplicitModelType) :: this
     integer(I4B), intent(in) :: icnvg
     integer(I4B), intent(in) :: isuppress_output
-    !
-    ! -- return
-    return
   end subroutine model_bd
 
   !> @ brief Deallocate the model
   !<
   subroutine model_da(this)
-    ! -- modules
-    use MemoryManagerModule, only: mem_deallocate
     class(ExplicitModelType) :: this
 
-    ! -- Scalars
-    !
-    ! -- Arrays
-    !
-    ! -- derived types
+    ! -- deallocate scalars
+    deallocate (this%filename)
+
+    ! -- deallocate arrays
+    call mem_deallocate(this%ibound)
+
+    ! -- nullify pointers
+    if (associated(this%ibound)) &
+      call mem_deallocate(this%ibound, 'IBOUND', this%memoryPath)
+
+    ! -- member derived types
     call this%bndlist%Clear()
     deallocate (this%bndlist)
-    !
-    ! -- nullify pointers
-    !
-    ! -- BaseModelType
+
+    ! -- deallocate base tpye
     call this%BaseModelType%model_da()
-    !
-    ! -- Return
-    return
   end subroutine model_da
 
-  !> @ brief Allocate model scalar variables
+  !> @ brief Allocate scalar variables
   !<
   subroutine allocate_scalars(this, modelname)
-    use MemoryManagerModule, only: mem_allocate
     class(ExplicitModelType) :: this
     character(len=*), intent(in) :: modelname
-    !
-    ! -- allocate basetype members
+
     call this%BaseModelType%allocate_scalars(modelname)
-    !
-    ! -- allocate members from this type
     allocate (this%bndlist)
-    !
-    ! -- initialize
-    !
-    ! -- return
-    return
+    allocate (this%filename)
+    this%filename = ''
   end subroutine allocate_scalars
 
+  !> @brief Allocate array variables
+  !<
+  subroutine allocate_arrays(this)
+    class(ExplicitModelType) :: this
+    integer(I4B) :: i
+
+    call mem_allocate(this%ibound, this%dis%nodes, 'IBOUND', this%memoryPath)
+    do i = 1, this%dis%nodes
+      this%ibound(i) = 1 ! active by default
+    end do
+  end subroutine allocate_arrays
+
   !> @ brief Cast a generic object into an explicit model
   !<
   function CastAsExplicitModelClass(obj) result(res)
     class(*), pointer, intent(inout) :: obj
     class(ExplicitModelType), pointer :: res
-    !
+
     res => null()
     if (.not. associated(obj)) return
-    !
+
     select type (obj)
     class is (ExplicitModelType)
       res => obj
     end select
-    return
   end function CastAsExplicitModelClass
 
   !> @ brief Add explicit model to a generic list
@@ -148,11 +138,9 @@ subroutine AddExplicitModelToList(list, model)
     class(ExplicitModelType), pointer, intent(inout) :: model
     ! -- local
     class(*), pointer :: obj
-    !
+
     obj => model
     call list%Add(obj)
-    !
-    return
   end subroutine AddExplicitModelToList
 
   !> @ brief Get generic object from list and return as explicit model
@@ -164,11 +152,17 @@ function GetExplicitModelFromList(list, idx) result(res)
     class(ExplicitModelType), pointer :: res
     ! -- local
     class(*), pointer :: obj
-    !
+
     obj => list%GetItem(idx)
     res => CastAsExplicitModelClass(obj)
-    !
-    return
   end function GetExplicitModelFromList
 
+  !> @brief Set the solution ID
+  !<
+  subroutine set_idsoln(this, id)
+    class(ExplicitModelType) :: this
+    integer(I4B), intent(in) :: id
+    this%idsoln = id
+  end subroutine set_idsoln
+
 end module ExplicitModelModule
diff --git a/src/Model/Geometry/BaseGeometry.f90 b/src/Model/Geometry/BaseGeometry.f90
index 0216abb793f..291f8530a5b 100644
--- a/src/Model/Geometry/BaseGeometry.f90
+++ b/src/Model/Geometry/BaseGeometry.f90
@@ -12,7 +12,9 @@ module BaseGeometryModule
     character(len=20) :: geo_type = 'UNDEFINED'
     integer(I4B) :: id = 0
     character(len=GEONAMELEN) :: name = ''
+
   contains
+
     procedure :: area_sat
     procedure :: perimeter_sat
     procedure :: area_wet
@@ -28,8 +30,10 @@ function area_sat(this)
     real(DP) :: area_sat
     ! -- dummy
     class(BaseGeometryType) :: this
+    !
     area_sat = 0.d0
-    ! -- return
+    !
+    ! -- Return
     return
   end function area_sat
 
@@ -38,8 +42,10 @@ function perimeter_sat(this)
     real(DP) :: perimeter_sat
     ! -- dummy
     class(BaseGeometryType) :: this
+    !
     perimeter_sat = 0.d0
-    ! -- return
+    !
+    ! -- Return
     return
   end function perimeter_sat
 
@@ -49,8 +55,10 @@ function area_wet(this, depth)
     ! -- dummy
     class(BaseGeometryType) :: this
     real(DP), intent(in) :: depth
+    !
     area_wet = 0.d0
-    ! -- return
+    !
+    ! -- Return
     return
   end function area_wet
 
@@ -60,8 +68,10 @@ function perimeter_wet(this, depth)
     ! -- dummy
     class(BaseGeometryType) :: this
     real(DP), intent(in) :: depth
+    !
     perimeter_wet = 0.d0
-    ! -- return
+    !
+    ! -- Return
     return
   end function perimeter_wet
 
@@ -69,17 +79,14 @@ subroutine set_attribute(this, line)
     ! -- dummy
     class(BaseGeometryType) :: this
     character(len=*), intent(inout) :: line
-    ! -- return
+    !
+    ! -- Return
     return
   end subroutine set_attribute
 
+  !> @brief Print the attributes for this object
+  !<
   subroutine print_attributes(this, iout)
-! ******************************************************************************
-! print_attributes -- print the attributes for this object
-! *****************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(BaseGeometryType) :: this
     ! -- local
@@ -87,13 +94,12 @@ subroutine print_attributes(this, iout)
     ! -- formats
     character(len=*), parameter :: fmtid = "(4x,a,i0)"
     character(len=*), parameter :: fmtnm = "(4x,a,a)"
-! ------------------------------------------------------------------------------
     !
     write (iout, fmtid) 'ID = ', this%id
     write (iout, fmtnm) 'NAME = ', trim(adjustl(this%name))
     write (iout, fmtnm) 'GEOMETRY TYPE = ', trim(adjustl(this%geo_type))
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine print_attributes
 
diff --git a/src/Model/Geometry/CircularGeometry.f90 b/src/Model/Geometry/CircularGeometry.f90
index 18e71a6491d..19f86362a87 100644
--- a/src/Model/Geometry/CircularGeometry.f90
+++ b/src/Model/Geometry/CircularGeometry.f90
@@ -10,7 +10,9 @@ module CircularGeometryModule
 
   type, extends(BaseGeometryType) :: CircularGeometryType
     real(DP) :: radius = DZERO
+
   contains
+
     procedure :: area_sat
     procedure :: perimeter_sat
     procedure :: area_wet
@@ -21,20 +23,15 @@ module CircularGeometryModule
 
 contains
 
+  !> @brief Return area as if geometry is fully saturated
+  !<
   function area_sat(this)
-! ******************************************************************************
-! area_sat -- return area as if geometry is fully saturated
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DTWO, DPI
     ! -- return
     real(DP) :: area_sat
     ! -- dummy
     class(CircularGeometryType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate area
     area_sat = DPI * this%radius**DTWO
@@ -43,35 +40,26 @@ function area_sat(this)
     return
   end function area_sat
 
+  !> @brief Return perimeter as if geometry is fully saturated
+  !<
   function perimeter_sat(this)
-! ******************************************************************************
-! perimeter_sat -- return perimeter as if geometry is fully saturated
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DTWO, DPI
     ! -- return
     real(DP) :: perimeter_sat
     ! -- dummy
     class(CircularGeometryType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate area
     perimeter_sat = DTWO * DPI * this%radius
     !
-    ! -- return
+    ! -- Return
     return
   end function perimeter_sat
 
+  !> @brief Return wetted area
+  !<
   function area_wet(this, depth)
-! ******************************************************************************
-! area_wet -- return wetted area
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DTWO, DPI, DZERO
     ! -- return
@@ -79,7 +67,6 @@ function area_wet(this, depth)
     ! -- dummy
     class(CircularGeometryType) :: this
     real(DP), intent(in) :: depth
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate area
     if (depth <= DZERO) then
@@ -102,13 +89,9 @@ function area_wet(this, depth)
     return
   end function area_wet
 
+  !> @brief Return wetted perimeter
+  !<
   function perimeter_wet(this, depth)
-! ******************************************************************************
-! perimeter_wet -- return wetted perimeter
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DTWO, DPI
     ! -- return
@@ -116,7 +99,6 @@ function perimeter_wet(this, depth)
     ! -- dummy
     class(CircularGeometryType) :: this
     real(DP), intent(in) :: depth
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate area
     if (depth <= DZERO) then
@@ -131,17 +113,13 @@ function perimeter_wet(this, depth)
       perimeter_wet = DTWO * DPI * this%radius
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end function perimeter_wet
 
+  !> @brief Set a parameter for this circular object
+  !<
   subroutine set_attribute(this, line)
-! ******************************************************************************
-! set_attribute -- set a parameter for this circular object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- module
     use InputOutputModule, only: urword
     use ConstantsModule, only: LINELENGTH
@@ -153,7 +131,6 @@ subroutine set_attribute(this, line)
     ! -- local
     integer(I4B) :: lloc, istart, istop, ival
     real(DP) :: rval
-! ------------------------------------------------------------------------------
     !
     ! -- should change this and set id if uninitialized or store it
     lloc = 1
@@ -175,17 +152,13 @@ subroutine set_attribute(this, line)
       call store_error(errmsg, terminate=.TRUE.)
     end select
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine set_attribute
 
+  !> @brief Print the attributes for this object
+  !<
   subroutine print_attributes(this, iout)
-! ******************************************************************************
-! print_attributes -- print the attributes for this object
-! *****************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(CircularGeometryType) :: this
     ! -- local
@@ -193,7 +166,6 @@ subroutine print_attributes(this, iout)
     ! -- formats
     character(len=*), parameter :: fmtnm = "(4x,a,a)"
     character(len=*), parameter :: fmttd = "(4x,a,1(1PG15.6))"
-! ------------------------------------------------------------------------------
     !
     ! -- call parent to print parent attributes
     call this%BaseGeometryType%print_attributes(iout)
@@ -203,7 +175,7 @@ subroutine print_attributes(this, iout)
     write (iout, fmttd) 'SATURATED AREA = ', this%area_sat()
     write (iout, fmttd) 'SATURATED WETTED PERIMETER = ', this%perimeter_sat()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine print_attributes
 
diff --git a/src/Model/Geometry/RectangularGeometry.f90 b/src/Model/Geometry/RectangularGeometry.f90
index 1df035584de..29279898b30 100644
--- a/src/Model/Geometry/RectangularGeometry.f90
+++ b/src/Model/Geometry/RectangularGeometry.f90
@@ -9,7 +9,9 @@ module RectangularGeometryModule
   type, extends(BaseGeometryType) :: RectangularGeometryType
     real(DP) :: height = DZERO
     real(DP) :: width = DZERO
+
   contains
+
     procedure :: area_sat
     procedure :: perimeter_sat
     procedure :: area_wet
@@ -20,20 +22,15 @@ module RectangularGeometryModule
 
 contains
 
+  !> @brief Return saturated area
+  !<
   function area_sat(this)
-! ******************************************************************************
-! area_sat -- return saturated area
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DTWO, DPI
     ! -- return
     real(DP) :: area_sat
     ! -- dummy
     class(RectangularGeometryType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate area
     area_sat = this%height * this%width
@@ -42,35 +39,26 @@ function area_sat(this)
     return
   end function area_sat
 
+  !> @brief Return saturated perimeter
+  !<
   function perimeter_sat(this)
-! ******************************************************************************
-! perimeter_sat -- return saturated perimeter
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DTWO, DPI
     ! -- return
     real(DP) :: perimeter_sat
     ! -- dummy
     class(RectangularGeometryType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate area
     perimeter_sat = DTWO * (this%height + this%width)
     !
-    ! -- return
+    ! -- Return
     return
   end function perimeter_sat
 
+  !> @brief Return wetted area
+  !<
   function area_wet(this, depth)
-! ******************************************************************************
-! area_wet -- return wetted area
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DTWO, DPI, DZERO
     ! -- return
@@ -78,7 +66,6 @@ function area_wet(this, depth)
     ! -- dummy
     class(RectangularGeometryType) :: this
     real(DP), intent(in) :: depth
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate area
     if (depth <= DZERO) then
@@ -93,13 +80,9 @@ function area_wet(this, depth)
     return
   end function area_wet
 
+  !> @brief Return wetted perimeter
+  !<
   function perimeter_wet(this, depth)
-! ******************************************************************************
-! perimeter_wet -- return wetted perimeter
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DTWO, DPI
     ! -- return
@@ -107,7 +90,6 @@ function perimeter_wet(this, depth)
     ! -- dummy
     class(RectangularGeometryType) :: this
     real(DP), intent(in) :: depth
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate area
     if (depth <= DZERO) then
@@ -118,17 +100,13 @@ function perimeter_wet(this, depth)
       perimeter_wet = DTWO * (this%height + this%width)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end function perimeter_wet
 
+  !> @brief Set a parameter for this rectangular object
+  !<
   subroutine set_attribute(this, line)
-! ******************************************************************************
-! set_attribute -- set a parameter for this rectangular object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- module
     use InputOutputModule, only: urword
     use ConstantsModule, only: LINELENGTH
@@ -140,13 +118,12 @@ subroutine set_attribute(this, line)
     ! -- local
     integer(I4B) :: lloc, istart, istop, ival
     real(DP) :: rval
-! ------------------------------------------------------------------------------
     !
     ! -- should change this and set id if uninitialized or store it
     lloc = 1
     call urword(line, lloc, istart, istop, 2, ival, rval, 0, 0)
     this%id = ival
-
+    !
     ! -- Parse the attribute
     call urword(line, lloc, istart, istop, 1, ival, rval, 0, 0)
     select case (line(istart:istop))
@@ -165,17 +142,13 @@ subroutine set_attribute(this, line)
       call store_error(errmsg, terminate=.TRUE.)
     end select
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine set_attribute
 
+  !> @brief Print the attributes for this object
+  !<
   subroutine print_attributes(this, iout)
-! ******************************************************************************
-! print_attributes -- print the attributes for this object
-! *****************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(RectangularGeometryType) :: this
     ! -- local
@@ -183,7 +156,6 @@ subroutine print_attributes(this, iout)
     ! -- formats
     character(len=*), parameter :: fmtnm = "(4x,a,a)"
     character(len=*), parameter :: fmttd = "(4x,a,1(1PG15.6))"
-! ------------------------------------------------------------------------------
     !
     ! -- call parent to print parent attributes
     call this%BaseGeometryType%print_attributes(iout)
@@ -194,7 +166,7 @@ subroutine print_attributes(this, iout)
     write (iout, fmttd) 'SATURATED AREA = ', this%area_sat()
     write (iout, fmttd) 'SATURATED WETTED PERIMETER = ', this%perimeter_sat()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine print_attributes
 
diff --git a/src/Model/GroundWaterFlow/gwf3.f90 b/src/Model/GroundWaterFlow/gwf3.f90
index 9a8057246be..00b44227c06 100644
--- a/src/Model/GroundWaterFlow/gwf3.f90
+++ b/src/Model/GroundWaterFlow/gwf3.f90
@@ -3,7 +3,7 @@ module GwfModule
   use KindModule, only: DP, I4B
   use InputOutputModule, only: ParseLine, upcase, lowcase
   use ConstantsModule, only: LENFTYPE, LENMEMPATH, LENPAKLOC, DZERO, &
-                             DEM1, DTEN, DEP20
+                             DEM1, DTEN, DEP20, LENPACKAGETYPE
   use VersionModule, only: write_listfile_header
   use NumericalModelModule, only: NumericalModelType
   use BaseDisModule, only: DisBaseType
@@ -32,6 +32,8 @@ module GwfModule
   public :: gwf_cr
   public :: GwfModelType
   public :: CastAsGwfModel
+  public :: GWF_NBASEPKG, GWF_NMULTIPKG
+  public :: GWF_BASEPKG, GWF_MULTIPKG
 
   type, extends(NumericalModelType) :: GwfModelType
 
@@ -99,6 +101,34 @@ module GwfModule
     !
   end type GwfModelType
 
+  !> @brief GWF base package array descriptors
+  !!
+  !! GWF6 model base package types.  Only listed packages are candidates
+  !! for input and these will be loaded in the order specified.
+  !<
+  integer(I4B), parameter :: GWF_NBASEPKG = 50
+  character(len=LENPACKAGETYPE), dimension(GWF_NBASEPKG) :: GWF_BASEPKG
+  data GWF_BASEPKG/'DIS6 ', 'DISV6', 'DISU6', '     ', '     ', & !  5
+                  &'NPF6 ', 'BUY6 ', 'VSC6 ', 'GNC6 ', '     ', & ! 10
+                  &'HFB6 ', 'STO6 ', 'IC6  ', '     ', '     ', & ! 15
+                  &'MVR6 ', 'OC6  ', 'OBS6 ', '     ', '     ', & ! 20
+                  &30*'     '/ ! 50
+
+  !> @brief GWF multi package array descriptors
+  !!
+  !! GWF6 model multi-instance package types.  Only listed packages are
+  !! candidates for input and these will be loaded in the order specified.
+  !<
+  integer(I4B), parameter :: GWF_NMULTIPKG = 50
+  character(len=LENPACKAGETYPE), dimension(GWF_NMULTIPKG) :: GWF_MULTIPKG
+  data GWF_MULTIPKG/'WEL6 ', 'DRN6 ', 'RIV6 ', 'GHB6 ', '     ', & !  5
+                   &'RCH6 ', 'EVT6 ', 'CHD6 ', 'CSUB6', '     ', & ! 10
+                   &'MAW6 ', 'SFR6 ', 'LAK6 ', 'UZF6 ', 'API6 ', & ! 15
+                   &35*'     '/ ! 50
+
+  ! -- size of supported model package arrays
+  integer(I4B), parameter :: NIUNIT_GWF = GWF_NBASEPKG + GWF_NMULTIPKG
+
 contains
 
   !> @brief Create a new groundwater flow model object
@@ -191,7 +221,6 @@ end subroutine gwf_cr
   !<
   subroutine gwf_df(this)
     ! -- modules
-    use ModelPackageInputsModule, only: NIUNIT_GWF
     ! -- dummy
     class(GwfModelType) :: this
     ! -- local
@@ -792,7 +821,7 @@ subroutine gwf_cq(this, icnvg, isuppress_output)
     !    head solution.
     do ip = 1, this%bndlist%Count()
       packobj => GetBndFromList(this%bndlist, ip)
-      call packobj%bnd_cf(reset_mover=.false.)
+      call packobj%bnd_cf()
       if (this%inbuy > 0) call this%buy%buy_cf_bnd(packobj, this%x)
       call packobj%bnd_cq(this%x, this%flowja)
     end do
@@ -1254,8 +1283,8 @@ end subroutine allocate_scalars
   !! (2) add a pointer to the package
   !!
   !<
-  subroutine package_create(this, filtyp, ipakid, ipaknum, pakname, inunit, &
-                            iout)
+  subroutine package_create(this, filtyp, ipakid, ipaknum, pakname, mempath, &
+                            inunit, iout)
     ! -- modules
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error
@@ -1278,6 +1307,7 @@ subroutine package_create(this, filtyp, ipakid, ipaknum, pakname, inunit, &
     integer(I4B), intent(in) :: ipakid
     integer(I4B), intent(in) :: ipaknum
     character(len=*), intent(in) :: pakname
+    character(len=*), intent(in) :: mempath
     integer(I4B), intent(in) :: inunit
     integer(I4B), intent(in) :: iout
     ! -- local
@@ -1289,19 +1319,26 @@ subroutine package_create(this, filtyp, ipakid, ipaknum, pakname, inunit, &
     ! -- This part creates the package object
     select case (filtyp)
     case ('CHD6')
-      call chd_create(packobj, ipakid, ipaknum, inunit, iout, this%name, pakname)
+      call chd_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
+                      pakname, mempath)
     case ('WEL6')
-      call wel_create(packobj, ipakid, ipaknum, inunit, iout, this%name, pakname)
+      call wel_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
+                      pakname, mempath)
     case ('DRN6')
-      call drn_create(packobj, ipakid, ipaknum, inunit, iout, this%name, pakname)
+      call drn_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
+                      pakname, mempath)
     case ('RIV6')
-      call riv_create(packobj, ipakid, ipaknum, inunit, iout, this%name, pakname)
+      call riv_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
+                      pakname, mempath)
     case ('GHB6')
-      call ghb_create(packobj, ipakid, ipaknum, inunit, iout, this%name, pakname)
+      call ghb_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
+                      pakname, mempath)
     case ('RCH6')
-      call rch_create(packobj, ipakid, ipaknum, inunit, iout, this%name, pakname)
+      call rch_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
+                      pakname, mempath)
     case ('EVT6')
-      call evt_create(packobj, ipakid, ipaknum, inunit, iout, this%name, pakname)
+      call evt_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
+                      pakname, mempath)
     case ('MAW6')
       call maw_create(packobj, ipakid, ipaknum, inunit, iout, this%name, pakname)
     case ('SFR6')
@@ -1432,8 +1469,8 @@ subroutine create_bndpkgs(this, bndpkgs, pkgtypes, pkgnames, &
           bndptype = pkgtype
         end if
         !
-        call this%package_create(pkgtype, ipakid, ipaknum, pkgname, inunit, &
-                                 this%iout)
+        call this%package_create(pkgtype, ipakid, ipaknum, pkgname, mempath, &
+                                 inunit, this%iout)
         ipakid = ipakid + 1
         ipaknum = ipaknum + 1
       end do
@@ -1489,6 +1526,7 @@ subroutine create_packages(this)
     integer(I4B) :: n
     integer(I4B) :: indis = 0 ! DIS enabled flag
     character(len=LENMEMPATH) :: mempathnpf = ''
+    character(len=LENMEMPATH) :: mempathic = ''
     !
     ! -- set input model memory path
     model_mempath = create_mem_path(component=this%name, context=idm_context)
@@ -1534,15 +1572,17 @@ subroutine create_packages(this)
       case ('CSUB6')
         this%incsub = inunit
       case ('IC6')
-        this%inic = inunit
+        this%inic = 1
+        mempathic = mempath
       case ('MVR6')
         this%inmvr = inunit
       case ('OC6')
         this%inoc = inunit
       case ('OBS6')
         this%inobs = inunit
-      case ('WEL6', 'DRN6', 'RIV6', 'GHB6', 'RCH6', 'EVT6', &
-            'API6', 'CHD6', 'MAW6', 'SFR6', 'LAK6', 'UZF6')
+      case ('WEL6', 'DRN6', 'RIV6', 'GHB6', 'RCH6', &
+            'EVT6', 'API6', 'CHD6', 'MAW6', 'SFR6', &
+            'LAK6', 'UZF6')
         call expandarray(bndpkgs)
         bndpkgs(size(bndpkgs)) = n
       case default
@@ -1560,7 +1600,7 @@ subroutine create_packages(this)
     call sto_cr(this%sto, this%name, this%insto, this%iout)
     call csub_cr(this%csub, this%name, this%insto, this%sto%packName, &
                  this%incsub, this%iout)
-    call ic_cr(this%ic, this%name, this%inic, this%iout, this%dis)
+    call ic_cr(this%ic, this%name, mempathic, this%inic, this%iout, this%dis)
     call mvr_cr(this%mvr, this%name, this%inmvr, this%iout, this%dis)
     call oc_cr(this%oc, this%name, this%inoc, this%iout)
     call gwf_obs_cr(this%obs, this%inobs)
diff --git a/src/Model/GroundWaterFlow/gwf3buy8.f90 b/src/Model/GroundWaterFlow/gwf3buy8.f90
index 39fbdf5629c..70f87f67f61 100644
--- a/src/Model/GroundWaterFlow/gwf3buy8.f90
+++ b/src/Model/GroundWaterFlow/gwf3buy8.f90
@@ -76,13 +76,9 @@ module GwfBuyModule
 
 contains
 
+  !> @brief Generic function to calculate fluid density from concentration
+  !<
   function calcdens(denseref, drhodc, crhoref, conc) result(dense)
-! ******************************************************************************
-! calcdens -- generic function to calculate fluid density from concentration
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     real(DP), intent(in) :: denseref
     real(DP), dimension(:), intent(in) :: drhodc
@@ -93,7 +89,6 @@ function calcdens(denseref, drhodc, crhoref, conc) result(dense)
     ! -- local
     integer(I4B) :: nrhospec
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     nrhospec = size(drhodc)
     dense = denseref
@@ -101,23 +96,18 @@ function calcdens(denseref, drhodc, crhoref, conc) result(dense)
       dense = dense + drhodc(i) * (conc(i) - crhoref(i))
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end function calcdens
 
+  !> @brief Create a new BUY object
+  !<
   subroutine buy_cr(buyobj, name_model, inunit, iout)
-! ******************************************************************************
-! buy_cr -- Create a new BUY object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(GwfBuyType), pointer :: buyobj
     character(len=*), intent(in) :: name_model
     integer(I4B), intent(in) :: inunit
     integer(I4B), intent(in) :: iout
-! ------------------------------------------------------------------------------
     !
     ! -- Create the object
     allocate (buyobj)
@@ -142,13 +132,6 @@ end subroutine buy_cr
   !> @brief Read options and package data, or set from argument
   !<
   subroutine buy_df(this, dis, buy_input)
-! ******************************************************************************
-! buy_df -- Allocate and Read
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfBuyType) :: this !< this buoyancy package
     class(DisBaseType), pointer, intent(in) :: dis !< pointer to discretization
@@ -158,7 +141,6 @@ subroutine buy_df(this, dis, buy_input)
     character(len=*), parameter :: fmtbuy = &
       "(1x,/1x,'BUY -- Buoyancy Package, Version 1, 5/16/2018', &
       &' input read from unit ', i0, //)"
-! ------------------------------------------------------------------------------
     !
     ! --print a message identifying the buoyancy package.
     write (this%iout, fmtbuy) this%inunit
@@ -195,21 +177,13 @@ subroutine buy_df(this, dis, buy_input)
     return
   end subroutine buy_df
 
+  !> @brief Allocate and Read
+  !<
   subroutine buy_ar(this, npf, ibound)
-! ******************************************************************************
-! buy_ar -- Allocate and Read
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfBuyType) :: this
     type(GwfNpfType), pointer, intent(in) :: npf
     integer(I4B), dimension(:), pointer :: ibound
-    ! -- local
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- store pointers to arguments that were passed in
     this%npf => npf
@@ -229,14 +203,11 @@ subroutine buy_ar(this, npf, ibound)
     return
   end subroutine buy_ar
 
+  !> @brief Buoyancy ar_bnd routine to activate density in packages
+  !!
+  !! This routine is called from gwf_ar() as it goes through each package
+  !<
   subroutine buy_ar_bnd(this, packobj, hnew)
-! ******************************************************************************
-! buy_ar_bnd -- buoyancy ar_bnd routine to activate density in packages.
-!   This routine is called from gwf_ar() as it goes through each package.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use BndModule, only: BndType
     use LakModule, only: LakType
@@ -246,8 +217,6 @@ subroutine buy_ar_bnd(this, packobj, hnew)
     class(GwfBuyType) :: this
     class(BndType), pointer :: packobj
     real(DP), intent(in), dimension(:) :: hnew
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- Add density terms based on boundary package type
     select case (packobj%filtyp)
@@ -258,7 +227,7 @@ subroutine buy_ar_bnd(this, packobj, hnew)
       type is (LakType)
         call packobj%lak_activate_density()
       end select
-
+      !
     case ('SFR')
       !
       ! -- activate density for sfr package
@@ -266,7 +235,7 @@ subroutine buy_ar_bnd(this, packobj, hnew)
       type is (SfrType)
         call packobj%sfr_activate_density()
       end select
-
+      !
     case ('MAW')
       !
       ! -- activate density for maw package
@@ -274,7 +243,7 @@ subroutine buy_ar_bnd(this, packobj, hnew)
       type is (MawType)
         call packobj%maw_activate_density()
       end select
-
+      !
     case default
       !
       ! -- nothing
@@ -284,13 +253,9 @@ subroutine buy_ar_bnd(this, packobj, hnew)
     return
   end subroutine buy_ar_bnd
 
+  !> @brief Check for new buy period data
+  !<
   subroutine buy_rp(this)
-! ******************************************************************************
-! buy_rp -- Check for new buy period data
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: kstp, kper
     ! -- dummy
@@ -304,7 +269,6 @@ subroutine buy_rp(this)
        &for species ',i0,'. One or more model names may be specified &
        &incorrectly in the PACKAGEDATA block or a gwf-gwt exchange may need &
        &to be activated.')"
-! ------------------------------------------------------------------------------
     !
     ! -- Check to make sure all concentration pointers have been set
     if (kstp * kper == 1) then
@@ -319,21 +283,15 @@ subroutine buy_rp(this)
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine buy_rp
 
+  !> @brief Advance
+  !<
   subroutine buy_ad(this)
-! ******************************************************************************
-! buy_ad -- Advance
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfBuyType) :: this
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- update density using the last concentration
     call this%buy_calcdens()
@@ -342,18 +300,12 @@ subroutine buy_ad(this)
     return
   end subroutine buy_ad
 
+  !> @brief Fill coefficients
+  !<
   subroutine buy_cf(this, kiter)
-! ******************************************************************************
-! buy_cf -- Fill coefficients
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfBuyType) :: this
     integer(I4B) :: kiter
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- Recalculate the elev array for this iteration
     if (this%ireadelev == 0) then
@@ -366,13 +318,9 @@ subroutine buy_cf(this, kiter)
     return
   end subroutine buy_cf
 
+  !> @brief Fill coefficients
+  !<
   subroutine buy_cf_bnd(this, packobj, hnew) !, hcof, rhs, auxnam, auxvar)
-! ******************************************************************************
-! buy_cf_bnd -- Fill coefficients
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use BndModule, only: BndType
     ! -- dummy
@@ -383,7 +331,6 @@ subroutine buy_cf_bnd(this, packobj, hnew) !, hcof, rhs, auxnam, auxvar)
     integer(I4B) :: i, j
     integer(I4B) :: n, locdense, locelev
     integer(I4B), dimension(:), allocatable :: locconc
-! ------------------------------------------------------------------------------
     !
     ! -- Return if freshwater head formulation; all boundary heads must be
     !    entered as freshwater equivalents
@@ -468,19 +415,14 @@ subroutine buy_cf_bnd(this, packobj, hnew) !, hcof, rhs, auxnam, auxvar)
     return
   end subroutine buy_cf_bnd
 
+  !> @brief Return the density of the boundary package using one of several
+  !! different options in the following order of priority:
+  !!     1. Assign as aux variable in column with name 'DENSITY'
+  !!     2. Calculate using equation of state and nrhospecies aux columns
+  !!     3. If neither of those, then assign as denseref
+  !<
   function get_bnd_density(n, locdense, locconc, denseref, drhodc, crhoref, &
                            ctemp, auxvar) result(densebnd)
-! ******************************************************************************
-! get_bnd_density -- Return the density of the boundary package using one of
-!   several different options in the following order of priority:
-!     1. Assign as aux variable in column with name 'DENSITY'
-!     2. Calculate using equation of state and nrhospecies aux columns
-!     3. If neither of those, then assign as denseref
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     integer(I4B), intent(in) :: n
     integer(I4B), intent(in) :: locdense
@@ -494,7 +436,6 @@ function get_bnd_density(n, locdense, locconc, denseref, drhodc, crhoref, &
     real(DP) :: densebnd
     ! -- local
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     ! -- assign boundary density based on one of three options
     if (locdense > 0) then
@@ -514,21 +455,18 @@ function get_bnd_density(n, locdense, locconc, denseref, drhodc, crhoref, &
       densebnd = denseref
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end function get_bnd_density
 
+  !> @brief Fill ghb coefficients
+  !<
   subroutine buy_cf_ghb(packobj, hnew, dense, elev, denseref, locelev, &
                         locdense, locconc, drhodc, crhoref, ctemp, &
                         iform)
-! ******************************************************************************
-! buy_cf_ghb -- Fill ghb coefficients
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use BndModule, only: BndType
+    use GhbModule, only: GhbType
     class(BndType), pointer :: packobj
     ! -- dummy
     real(DP), intent(in), dimension(:) :: hnew
@@ -550,48 +488,45 @@ subroutine buy_cf_ghb(packobj, hnew, dense, elev, denseref, locelev, &
     real(DP) :: hghb
     real(DP) :: cond
     real(DP) :: hcofterm, rhsterm
-! ------------------------------------------------------------------------------
     !
     ! -- Process density terms for each GHB
-    do n = 1, packobj%nbound
-      node = packobj%nodelist(n)
-      if (packobj%ibound(node) <= 0) cycle
-      !
-      ! -- density
-      denseghb = get_bnd_density(n, locdense, locconc, denseref, &
-                                 drhodc, crhoref, ctemp, packobj%auxvar)
-      !
-      ! -- elevation
-      elevghb = elev(node)
-      if (locelev > 0) elevghb = packobj%auxvar(locelev, n)
-      !
-      ! -- boundary head and conductance
-      hghb = packobj%bound(1, n)
-      cond = packobj%bound(2, n)
-      !
-      ! -- calculate HCOF and RHS terms
-      call calc_ghb_hcof_rhs_terms(denseref, denseghb, dense(node), &
-                                   elevghb, elev(node), hghb, hnew(node), &
-                                   cond, iform, rhsterm, hcofterm)
-      packobj%hcof(n) = packobj%hcof(n) + hcofterm
-      packobj%rhs(n) = packobj%rhs(n) - rhsterm
-      !
-    end do
+    select type (packobj)
+    type is (GhbType)
+      do n = 1, packobj%nbound
+        node = packobj%nodelist(n)
+        if (packobj%ibound(node) <= 0) cycle
+        !
+        ! -- density
+        denseghb = get_bnd_density(n, locdense, locconc, denseref, &
+                                   drhodc, crhoref, ctemp, packobj%auxvar)
+        !
+        ! -- elevation
+        elevghb = elev(node)
+        if (locelev > 0) elevghb = packobj%auxvar(locelev, n)
+        !
+        ! -- boundary head and conductance
+        hghb = packobj%bhead(n)
+        cond = packobj%cond(n)
+        !
+        ! -- calculate HCOF and RHS terms
+        call calc_ghb_hcof_rhs_terms(denseref, denseghb, dense(node), &
+                                     elevghb, elev(node), hghb, hnew(node), &
+                                     cond, iform, rhsterm, hcofterm)
+        packobj%hcof(n) = packobj%hcof(n) + hcofterm
+        packobj%rhs(n) = packobj%rhs(n) - rhsterm
+        !
+      end do
+    end select
     !
     ! -- Return
     return
   end subroutine buy_cf_ghb
 
+  !> @brief Calculate density hcof and rhs terms for ghb conditions
+  !<
   subroutine calc_ghb_hcof_rhs_terms(denseref, denseghb, densenode, &
                                      elevghb, elevnode, hghb, hnode, &
                                      cond, iform, rhsterm, hcofterm)
-! ******************************************************************************
-! calc_ghb_hcof_rhs_terms -- Calculate density hcof and rhs terms for ghb
-!   conditions
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     real(DP), intent(in) :: denseref
     real(DP), intent(in) :: denseghb
@@ -607,7 +542,6 @@ subroutine calc_ghb_hcof_rhs_terms(denseref, denseghb, densenode, &
     ! -- local
     real(DP) :: t1, t2
     real(DP) :: avgdense, avgelev
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate common terms
     avgdense = DHALF * denseghb + DHALF * densenode
@@ -633,21 +567,18 @@ subroutine calc_ghb_hcof_rhs_terms(denseref, denseghb, densenode, &
       rhsterm = rhsterm + DHALF * cond * t2 * hnode
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine calc_ghb_hcof_rhs_terms
 
+  !> @brief Fill riv coefficients
+  !<
   subroutine buy_cf_riv(packobj, hnew, dense, elev, denseref, locelev, &
                         locdense, locconc, drhodc, crhoref, ctemp, &
                         iform)
-! ******************************************************************************
-! buy_cf_riv -- Fill riv coefficients
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use BndModule, only: BndType
+    use RivModule, only: RivType
     class(BndType), pointer :: packobj
     ! -- dummy
     real(DP), intent(in), dimension(:) :: hnew
@@ -671,56 +602,55 @@ subroutine buy_cf_riv(packobj, hnew, dense, elev, denseref, locelev, &
     real(DP) :: cond
     real(DP) :: hcofterm
     real(DP) :: rhsterm
-! ------------------------------------------------------------------------------
     !
     ! -- Process density terms for each RIV
-    do n = 1, packobj%nbound
-      node = packobj%nodelist(n)
-      if (packobj%ibound(node) <= 0) cycle
-      !
-      ! -- density
-      denseriv = get_bnd_density(n, locdense, locconc, denseref, &
-                                 drhodc, crhoref, ctemp, packobj%auxvar)
-      !
-      ! -- elevation
-      elevriv = elev(node)
-      if (locelev > 0) elevriv = packobj%auxvar(locelev, n)
-      !
-      ! -- boundary head and conductance
-      hriv = packobj%bound(1, n)
-      cond = packobj%bound(2, n)
-      rbot = packobj%bound(3, n)
-      !
-      ! -- calculate and add terms depending on whether head is above rbot
-      if (hnew(node) > rbot) then
+    select type (packobj)
+    type is (RivType)
+      do n = 1, packobj%nbound
+        node = packobj%nodelist(n)
+        if (packobj%ibound(node) <= 0) cycle
         !
-        ! --calculate HCOF and RHS terms, similar to GHB in this case
-        call calc_ghb_hcof_rhs_terms(denseref, denseriv, dense(node), &
-                                     elevriv, elev(node), hriv, hnew(node), &
-                                     cond, iform, rhsterm, hcofterm)
-      else
-        hcofterm = DZERO
-        rhsterm = cond * (denseriv / denseref - DONE) * (hriv - rbot)
-      end if
-      !
-      ! -- Add terms to package hcof and rhs accumulators
-      packobj%hcof(n) = packobj%hcof(n) + hcofterm
-      packobj%rhs(n) = packobj%rhs(n) - rhsterm
-    end do
+        ! -- density
+        denseriv = get_bnd_density(n, locdense, locconc, denseref, &
+                                   drhodc, crhoref, ctemp, packobj%auxvar)
+        !
+        ! -- elevation
+        elevriv = elev(node)
+        if (locelev > 0) elevriv = packobj%auxvar(locelev, n)
+        !
+        ! -- boundary head and conductance
+        hriv = packobj%stage(n)
+        cond = packobj%cond(n)
+        rbot = packobj%rbot(n)
+        !
+        ! -- calculate and add terms depending on whether head is above rbot
+        if (hnew(node) > rbot) then
+          !
+          ! --calculate HCOF and RHS terms, similar to GHB in this case
+          call calc_ghb_hcof_rhs_terms(denseref, denseriv, dense(node), &
+                                       elevriv, elev(node), hriv, hnew(node), &
+                                       cond, iform, rhsterm, hcofterm)
+        else
+          hcofterm = DZERO
+          rhsterm = cond * (denseriv / denseref - DONE) * (hriv - rbot)
+        end if
+        !
+        ! -- Add terms to package hcof and rhs accumulators
+        packobj%hcof(n) = packobj%hcof(n) + hcofterm
+        packobj%rhs(n) = packobj%rhs(n) - rhsterm
+      end do
+    end select
     !
     ! -- Return
     return
   end subroutine buy_cf_riv
 
+  !> @brief Fill drn coefficients
+  !<
   subroutine buy_cf_drn(packobj, hnew, dense, denseref)
-! ******************************************************************************
-! buy_cf_drn -- Fill drn coefficients
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use BndModule, only: BndType
+    use DrnModule, only: DrnType
     class(BndType), pointer :: packobj
     ! -- dummy
     real(DP), intent(in), dimension(:) :: hnew
@@ -734,37 +664,35 @@ subroutine buy_cf_drn(packobj, hnew, dense, denseref)
     real(DP) :: cond
     real(DP) :: hcofterm
     real(DP) :: rhsterm
-! ------------------------------------------------------------------------------
     !
     ! -- Process density terms for each DRN
-    do n = 1, packobj%nbound
-      node = packobj%nodelist(n)
-      if (packobj%ibound(node) <= 0) cycle
-      rho = dense(node)
-      hbnd = packobj%bound(1, n)
-      cond = packobj%bound(2, n)
-      if (hnew(node) > hbnd) then
-        hcofterm = -cond * (rho / denseref - DONE)
-        rhsterm = hcofterm * hbnd
-        packobj%hcof(n) = packobj%hcof(n) + hcofterm
-        packobj%rhs(n) = packobj%rhs(n) + rhsterm
-      end if
-    end do
+    select type (packobj)
+    type is (DrnType)
+      do n = 1, packobj%nbound
+        node = packobj%nodelist(n)
+        if (packobj%ibound(node) <= 0) cycle
+        rho = dense(node)
+        hbnd = packobj%elev(n)
+        cond = packobj%cond(n)
+        if (hnew(node) > hbnd) then
+          hcofterm = -cond * (rho / denseref - DONE)
+          rhsterm = hcofterm * hbnd
+          packobj%hcof(n) = packobj%hcof(n) + hcofterm
+          packobj%rhs(n) = packobj%rhs(n) + rhsterm
+        end if
+      end do
+    end select
     !
     ! -- Return
     return
   end subroutine buy_cf_drn
 
+  !> @brief Pass density information into lak package; density terms are
+  !! calculated in the lake package as part of lak_calculate_density_exchange
+  !! method
+  !<
   subroutine buy_cf_lak(packobj, hnew, dense, elev, denseref, locdense, &
                         locconc, drhodc, crhoref, ctemp, iform)
-! ******************************************************************************
-! buy_cf_lak -- Pass density information into lak package; density terms are
-!   calculated in the lake package as part of lak_calculate_density_exchange
-!   method
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use BndModule, only: BndType
     use LakModule, only: LakType
@@ -784,7 +712,6 @@ subroutine buy_cf_lak(packobj, hnew, dense, elev, denseref, locdense, &
     integer(I4B) :: n
     integer(I4B) :: node
     real(DP) :: denselak
-! ------------------------------------------------------------------------------
     !
     ! -- Insert the lake and gwf relative densities into col 1 and 2 and the
     !    gwf elevation into col 3 of the lake package denseterms array
@@ -816,16 +743,12 @@ subroutine buy_cf_lak(packobj, hnew, dense, elev, denseref, locdense, &
     return
   end subroutine buy_cf_lak
 
+  !> @brief Pass density information into sfr package; density terms are
+  !! calculated in the sfr package as part of sfr_calculate_density_exchange
+  !! method
+  !<
   subroutine buy_cf_sfr(packobj, hnew, dense, elev, denseref, locdense, &
                         locconc, drhodc, crhoref, ctemp, iform)
-! ******************************************************************************
-! buy_cf_sfr -- Pass density information into sfr package; density terms are
-!   calculated in the sfr package as part of sfr_calculate_density_exchange
-!   method
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use BndModule, only: BndType
     use SfrModule, only: SfrType
@@ -845,7 +768,6 @@ subroutine buy_cf_sfr(packobj, hnew, dense, elev, denseref, locdense, &
     integer(I4B) :: n
     integer(I4B) :: node
     real(DP) :: densesfr
-! ------------------------------------------------------------------------------
     !
     ! -- Insert the sfr and gwf relative densities into col 1 and 2 and the
     !    gwf elevation into col 3 of the sfr package denseterms array
@@ -877,16 +799,12 @@ subroutine buy_cf_sfr(packobj, hnew, dense, elev, denseref, locdense, &
     return
   end subroutine buy_cf_sfr
 
+  !> @brief Pass density information into maw package; density terms are
+  !! calculated in the maw package as part of maw_calculate_density_exchange
+  !! method
+  !<
   subroutine buy_cf_maw(packobj, hnew, dense, elev, denseref, locdense, &
                         locconc, drhodc, crhoref, ctemp, iform)
-! ******************************************************************************
-! buy_cf_maw -- Pass density information into maw package; density terms are
-!   calculated in the maw package as part of maw_calculate_density_exchange
-!   method
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use BndModule, only: BndType
     use MawModule, only: MawType
@@ -906,7 +824,6 @@ subroutine buy_cf_maw(packobj, hnew, dense, elev, denseref, locdense, &
     integer(I4B) :: n
     integer(I4B) :: node
     real(DP) :: densemaw
-! ------------------------------------------------------------------------------
     !
     ! -- Insert the maw and gwf relative densities into col 1 and 2 and the
     !    gwf elevation into col 3 of the maw package denseterms array
@@ -938,13 +855,9 @@ subroutine buy_cf_maw(packobj, hnew, dense, elev, denseref, locdense, &
     return
   end subroutine buy_cf_maw
 
+  !> @brief Fill coefficients
+  !<
   subroutine buy_fc(this, kiter, matrix_sln, idxglo, rhs, hnew)
-! ******************************************************************************
-! buy_fc -- Fill coefficients
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfBuyType) :: this
     integer(I4B) :: kiter
@@ -955,7 +868,7 @@ subroutine buy_fc(this, kiter, matrix_sln, idxglo, rhs, hnew)
     ! -- local
     integer(I4B) :: n, m, ipos, idiag
     real(DP) :: rhsterm, amatnn, amatnm
-! ------------------------------------------------------------------------------
+    !
     ! -- initialize
     amatnn = DZERO
     amatnm = DZERO
@@ -985,13 +898,9 @@ subroutine buy_fc(this, kiter, matrix_sln, idxglo, rhs, hnew)
     return
   end subroutine buy_fc
 
+  !> @brief Save density array to binary file
+  !<
   subroutine buy_ot_dv(this, idvfl)
-! ******************************************************************************
-! buy_ot_dv -- Save density array to binary file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfBuyType) :: this
     integer(I4B), intent(in) :: idvfl
@@ -1002,7 +911,6 @@ subroutine buy_ot_dv(this, idvfl)
     integer(I4B) :: nvaluesp
     integer(I4B) :: nwidthp
     real(DP) :: dinact
-! ------------------------------------------------------------------------------
     !
     ! -- Set unit number for density output
     if (this%ioutdense /= 0) then
@@ -1025,19 +933,14 @@ subroutine buy_ot_dv(this, idvfl)
                                    nwidthp, editdesc, dinact)
       end if
     end if
-
     !
     ! -- Return
     return
   end subroutine buy_ot_dv
 
+  !> @brief Add buy term to flowja
+  !<
   subroutine buy_cq(this, hnew, flowja)
-! ******************************************************************************
-! buy_cq -- Add buy term to flowja
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     implicit none
     class(GwfBuyType) :: this
     real(DP), intent(in), dimension(:) :: hnew
@@ -1045,7 +948,6 @@ subroutine buy_cq(this, hnew, flowja)
     integer(I4B) :: n, m, ipos
     real(DP) :: deltaQ
     real(DP) :: rhsterm, amatnn, amatnm
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate the flow across each cell face and store in flowja
     do n = 1, this%dis%nodes
@@ -1071,17 +973,11 @@ subroutine buy_cq(this, hnew, flowja)
     return
   end subroutine buy_cq
 
+  !> @brief Deallocate
+  !<
   subroutine buy_da(this)
-! ******************************************************************************
-! buy_da -- Deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfBuyType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Deallocate arrays if package was active
     if (this%inunit > 0) then
@@ -1103,7 +999,7 @@ subroutine buy_da(this)
     call mem_deallocate(this%ireadconcbuy)
     call mem_deallocate(this%iconcset)
     call mem_deallocate(this%denseref)
-
+    !
     call mem_deallocate(this%nrhospecies)
     !
     ! -- deallocate parent
@@ -1113,14 +1009,9 @@ subroutine buy_da(this)
     return
   end subroutine buy_da
 
+  !> @brief Read the dimensions for this package
+  !<
   subroutine read_dimensions(this)
-! ******************************************************************************
-! read_dimensions -- Read the dimensions for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfBuyType), intent(inout) :: this
     ! -- local
@@ -1128,7 +1019,6 @@ subroutine read_dimensions(this)
     integer(I4B) :: ierr
     logical :: isfound, endOfBlock
     ! -- format
-! ------------------------------------------------------------------------------
     !
     ! -- get dimensions block
     call this%parser%GetBlock('DIMENSIONS', isfound, ierr, &
@@ -1164,18 +1054,13 @@ subroutine read_dimensions(this)
       call this%parser%StoreErrorUnit()
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine read_dimensions
 
+  !> @brief Read PACKAGEDATA block
+  !<
   subroutine read_packagedata(this)
-! ******************************************************************************
-! read_packagedata -- Read PACKAGEDATA block
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfBuyType) :: this
     ! -- local
@@ -1193,7 +1078,6 @@ subroutine read_packagedata(this)
       "('Invalid value for IRHOSPEC (',i0,') detected in BUY Package. &
       &IRHOSPEC must be > 0 and <= NRHOSPECIES, and duplicate values &
       &are not allowed.')"
-! ------------------------------------------------------------------------------
     !
     ! -- initialize
     allocate (itemp(this%nrhospecies))
@@ -1259,16 +1143,17 @@ subroutine read_packagedata(this)
     ! -- deallocate
     deallocate (itemp)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine read_packagedata
 
   !> @brief Sets package data instead of reading from file
   !<
   subroutine set_packagedata(this, input_data)
+    ! -- dummy
     class(GwfBuyType) :: this !< this buyoancy pkg
     type(GwfBuyInputDataType), intent(in) :: input_data !< the input data to be set
-    ! local
+    ! -- local
     integer(I4B) :: ispec
 
     do ispec = 1, this%nrhospecies
@@ -1277,16 +1162,14 @@ subroutine set_packagedata(this, input_data)
       this%cmodelname(ispec) = input_data%cmodelname(ispec)
       this%cauxspeciesname(ispec) = input_data%cauxspeciesname(ispec)
     end do
-
+    !
+    ! -- Return
+    return
   end subroutine set_packagedata
 
+  !> @brief Calculate buyancy term for this connection
+  !<
   subroutine calcbuy(this, n, m, icon, hn, hm, buy)
-! ******************************************************************************
-! calcbuy -- Calculate buyancy term for this connection
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use GwfNpfModule, only: hcond, vcond
     ! -- dummy
@@ -1303,7 +1186,6 @@ subroutine calcbuy(this, n, m, icon, hn, hm, buy)
                 cond, tp, bt
     real(DP) :: hyn
     real(DP) :: hym
-! ------------------------------------------------------------------------------
     !
     ! -- Average density
     densen = this%dense(n)
@@ -1371,13 +1253,9 @@ subroutine calcbuy(this, n, m, icon, hn, hm, buy)
     return
   end subroutine calcbuy
 
+  !> @brief Calculate hydraulic head term for this connection
+  !<
   subroutine calchhterms(this, n, m, icon, hn, hm, rhsterm, amatnn, amatnm)
-! ******************************************************************************
-! calchhterms -- Calculate hydraulic head term for this connection
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use GwfNpfModule, only: hcond, vcond
     ! -- dummy
@@ -1399,7 +1277,6 @@ subroutine calchhterms(this, n, m, icon, hn, hm, rhsterm, amatnn, amatnm)
     real(DP) :: hphi
     real(DP) :: hyn
     real(DP) :: hym
-! ------------------------------------------------------------------------------
     !
     ! -- Average density
     densen = this%dense(n)
@@ -1473,20 +1350,15 @@ subroutine calchhterms(this, n, m, icon, hn, hm, rhsterm, amatnn, amatnm)
     return
   end subroutine calchhterms
 
+  !> @brief calculate fluid density from concentration
+  !<
   subroutine buy_calcdens(this)
-! ******************************************************************************
-! buy_calcdens -- calculate fluid density from concentration
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfBuyType) :: this
 
     ! -- local
     integer(I4B) :: n
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate the density using the specified concentration array
     do n = 1, this%dis%nodes
@@ -1505,19 +1377,14 @@ subroutine buy_calcdens(this)
     return
   end subroutine buy_calcdens
 
+  !> @brief Calculate cell elevations to use in density flow equations
+  !<
   subroutine buy_calcelev(this)
-! ******************************************************************************
-! buy_calcelev -- Calculate cell elevations to use in density flow equations
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfBuyType) :: this
     ! -- local
     integer(I4B) :: n
     real(DP) :: tp, bt, frac
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate the elev array
     do n = 1, this%dis%nodes
@@ -1531,19 +1398,14 @@ subroutine buy_calcelev(this)
     return
   end subroutine buy_calcelev
 
+  !> @brief Allocate scalars used by the package
+  !<
   subroutine allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DZERO
     ! -- dummy
     class(GwfBuyType) :: this
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- allocate scalars in NumericalPackageType
     call this%NumericalPackageType%allocate_scalars()
@@ -1555,9 +1417,8 @@ subroutine allocate_scalars(this)
     call mem_allocate(this%ireadconcbuy, 'IREADCONCBUY', this%memoryPath)
     call mem_allocate(this%iconcset, 'ICONCSET', this%memoryPath)
     call mem_allocate(this%denseref, 'DENSEREF', this%memoryPath)
-
+    !
     call mem_allocate(this%nrhospecies, 'NRHOSPECIES', this%memoryPath)
-
     !
     ! -- Initialize
     this%ioutdense = 0
@@ -1565,9 +1426,8 @@ subroutine allocate_scalars(this)
     this%iconcset = 0
     this%ireadconcbuy = 0
     this%denseref = 1000.d0
-
+    !
     this%nrhospecies = 0
-
     !
     ! -- Initialize default to LHS implementation of hydraulic head formulation
     this%iform = 2
@@ -1577,20 +1437,14 @@ subroutine allocate_scalars(this)
     return
   end subroutine allocate_scalars
 
+  !> @brief Allocate arrays used by the package
+  !<
   subroutine allocate_arrays(this, nodes)
-! ******************************************************************************
-! allocate_arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfBuyType) :: this
     integer(I4B), intent(in) :: nodes
     ! -- local
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate
     call mem_allocate(this%dense, nodes, 'DENSE', this%memoryPath)
@@ -1622,13 +1476,9 @@ subroutine allocate_arrays(this, nodes)
     return
   end subroutine allocate_arrays
 
+  !> @brief Read package options
+  !<
   subroutine read_options(this)
-! ******************************************************************************
-! read_options
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use OpenSpecModule, only: access, form
     use InputOutputModule, only: urword, getunit, urdaux, openfile
@@ -1643,7 +1493,6 @@ subroutine read_options(this)
     character(len=*), parameter :: fmtfileout = &
       "(4x, 'BUY ', 1x, a, 1x, ' will be saved to file: ', &
       &a, /4x, 'opened on unit: ', I7)"
-! ------------------------------------------------------------------------------
     !
     ! -- get options block
     call this%parser%GetBlock('OPTIONS', isfound, ierr, &
@@ -1704,31 +1553,30 @@ end subroutine read_options
   !> @brief Sets options as opposed to reading them from a file
   !<
   subroutine set_options(this, input_data)
+    ! -- dummy
     class(GwfBuyType) :: this
     type(GwfBuyInputDataType), intent(in) :: input_data !< the input data to be set
-
+    !
     this%iform = input_data%iform
     this%denseref = input_data%denseref
-
+    !
     ! derived option:
     ! if not iform==2, there is no asymmetry
     if (this%iform == 0 .or. this%iform == 1) then
       this%iasym = 0
     end if
-
+    !
+    ! -- Return
+    return
   end subroutine set_options
 
+  !> @brief Pass in a gwt model name, concentration array and ibound, and store
+  !! a pointer to these in the BUY package so that density can be calculated
+  !! from them
+  !!
+  !! This routine is called from the gwfgwt exchange in the exg_ar() method
+  !<
   subroutine set_concentration_pointer(this, modelname, conc, icbund)
-! ******************************************************************************
-! set_concentration_pointer -- pass in a gwt model name, concentration array
-!   and ibound, and store a pointer to these in the BUY package so that
-!   density can be calculated from them.
-!   This routine is called from the gwfgwt exchange in the exg_ar() method.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfBuyType) :: this
     character(len=LENMODELNAME), intent(in) :: modelname
@@ -1737,7 +1585,6 @@ subroutine set_concentration_pointer(this, modelname, conc, icbund)
     ! -- local
     integer(I4B) :: i
     logical :: found
-! ------------------------------------------------------------------------------
     !
     this%iconcset = 1
     found = .false.
diff --git a/src/Model/GroundWaterFlow/gwf3chd8.f90 b/src/Model/GroundWaterFlow/gwf3chd8.f90
index 5b55207e1cc..3b7c7c26a16 100644
--- a/src/Model/GroundWaterFlow/gwf3chd8.f90
+++ b/src/Model/GroundWaterFlow/gwf3chd8.f90
@@ -3,9 +3,12 @@ module ChdModule
   use KindModule, only: DP, I4B
   use ConstantsModule, only: DZERO, DONE, NAMEDBOUNDFLAG, LENFTYPE, &
                              LINELENGTH, LENPACKAGENAME
+  use SimVariablesModule, only: errmsg
+  use SimModule, only: count_errors, store_error, store_error_filename
   use MemoryHelperModule, only: create_mem_path
   use ObsModule, only: DefaultObsIdProcessor
   use BndModule, only: BndType
+  use BndExtModule, only: BndExtType
   use ObserveModule, only: ObserveType
   use TimeSeriesLinkModule, only: TimeSeriesLinkType, &
                                   GetTimeSeriesLinkFromList
@@ -19,7 +22,8 @@ module ChdModule
   character(len=LENFTYPE) :: ftype = 'CHD'
   character(len=LENPACKAGENAME) :: text = '             CHD'
   !
-  type, extends(BndType) :: ChdType
+  type, extends(BndExtType) :: ChdType
+    real(DP), dimension(:), pointer, contiguous :: head => null() !< constant head array
     real(DP), dimension(:), pointer, contiguous :: ratechdin => null() !simulated flows into constant head (excluding other chds)
     real(DP), dimension(:), pointer, contiguous :: ratechdout => null() !simulated flows out of constant head (excluding to other chds)
   contains
@@ -32,24 +36,23 @@ module ChdModule
     procedure :: bnd_da => chd_da
     procedure :: allocate_arrays => chd_allocate_arrays
     procedure :: define_listlabel
+    procedure :: bound_value => chd_bound_value
+    procedure :: head_mult
     ! -- methods for observations
     procedure, public :: bnd_obs_supported => chd_obs_supported
     procedure, public :: bnd_df_obs => chd_df_obs
-    ! -- method for time series
-    procedure, public :: bnd_rp_ts => chd_rp_ts
+    !
+    procedure, private :: calc_chd_rate
   end type ChdType
 
 contains
 
-  subroutine chd_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
-! ******************************************************************************
-! chd_create -- Create a New Constant Head Package
-! Subroutine: (1) create new-style package
-!             (2) point packobj to the new package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Create a new constant head package
+  !!
+  !! Routine points packobj to the newly created package
+  !<
+  subroutine chd_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
+                        mempath)
     ! -- dummy
     class(BndType), pointer :: packobj
     integer(I4B), intent(in) :: id
@@ -58,20 +61,20 @@ subroutine chd_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     integer(I4B), intent(in) :: iout
     character(len=*), intent(in) :: namemodel
     character(len=*), intent(in) :: pakname
+    character(len=*), intent(in) :: mempath
     ! -- local
     type(ChdType), pointer :: chdobj
-! ------------------------------------------------------------------------------
     !
     ! -- allocate the object and assign values to object variables
     allocate (chdobj)
     packobj => chdobj
     !
     ! -- create name and memory path
-    call packobj%set_names(ibcnum, namemodel, pakname, ftype)
+    call packobj%set_names(ibcnum, namemodel, pakname, ftype, mempath)
     packobj%text = text
     !
     ! -- allocate scalars
-    call packobj%allocate_scalars()
+    call chdobj%allocate_scalars()
     !
     ! -- initialize package
     call packobj%pack_initialize()
@@ -81,33 +84,26 @@ subroutine chd_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     packobj%iout = iout
     packobj%id = id
     packobj%ibcnum = ibcnum
-    packobj%ncolbnd = 1
-    packobj%iscloc = 1
     packobj%ictMemPath = create_mem_path(namemodel, 'NPF')
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine chd_create
 
+  !> @brief Allocate arrays specific to the constant head package
+  !<
   subroutine chd_allocate_arrays(this, nodelist, auxvar)
-! ******************************************************************************
-! allocate_scalars -- allocate arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
-    use MemoryManagerModule, only: mem_allocate
+    use MemoryManagerModule, only: mem_allocate, mem_setptr, mem_checkin
     ! -- dummy
     class(ChdType) :: this
     integer(I4B), dimension(:), pointer, contiguous, optional :: nodelist
     real(DP), dimension(:, :), pointer, contiguous, optional :: auxvar
     ! -- local
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     ! -- call standard BndType allocate scalars
-    call this%BndType%allocate_arrays()
+    call this%BndExtType%allocate_arrays(nodelist, auxvar)
     !
     ! -- allocate ratechdex
     call mem_allocate(this%ratechdin, this%maxbound, 'RATECHDIN', this%memoryPath)
@@ -118,25 +114,29 @@ subroutine chd_allocate_arrays(this, nodelist, auxvar)
       this%ratechdout(i) = DZERO
     end do
     !
-    ! -- return
+    ! -- set constant head array input context pointer
+    call mem_setptr(this%head, 'HEAD', this%input_mempath)
+    !
+    ! -- checkin constant head array input context pointer
+    call mem_checkin(this%head, 'HEAD', this%memoryPath, &
+                     'HEAD', this%input_mempath)
+    !
+    ! -- Return
     return
   end subroutine chd_allocate_arrays
 
+  !> @brief Constant concentration/temperature read and prepare (rp) routine
+  !<
   subroutine chd_rp(this)
-! ******************************************************************************
-! chd_rp -- Read and prepare
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use SimModule, only: store_error
+    !
+    use TdisModule, only: kper
     ! -- dummy
     class(ChdType), intent(inout) :: this
     ! -- local
-    character(len=LINELENGTH) :: errmsg
     character(len=30) :: nodestr
     integer(I4B) :: i, node, ibd, ierr
-! ------------------------------------------------------------------------------
+    !
+    if (this%iper /= kper) return
     !
     ! -- Reset previous CHDs to active cell
     do i = 1, this%nbound
@@ -145,7 +145,7 @@ subroutine chd_rp(this)
     end do
     !
     ! -- Call the parent class read and prepare
-    call this%BndType%bnd_rp()
+    call this%BndExtType%bnd_rp()
     !
     ! -- Set ibound to -(ibcnum + 1) for constant head cells
     ierr = 0
@@ -165,20 +165,23 @@ subroutine chd_rp(this)
     !
     ! -- Stop if errors detected
     if (ierr > 0) then
-      call this%parser%StoreErrorUnit()
+      call store_error_filename(this%input_fname)
     end if
     !
-    ! -- return
+    ! -- Write the list to iout if requested
+    if (this%iprpak /= 0) then
+      call this%write_list()
+    end if
+    !
+    ! -- Return
     return
   end subroutine chd_rp
 
+  !> @brief Constant head package advance routine
+  !!
+  !! Add package connections to matrix
+  !<
   subroutine chd_ad(this)
-! ******************************************************************************
-! chd_ad -- Advance
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(ChdType) :: this
@@ -186,15 +189,12 @@ subroutine chd_ad(this)
     integer(I4B) :: i, node
     real(DP) :: hb
     ! -- formats
-! ------------------------------------------------------------------------------
-    !
-    ! -- Advance the time series
-    call this%TsManager%ad()
     !
     ! -- Process each entry in the specified-head cell list
     do i = 1, this%nbound
       node = this%nodelist(i)
-      hb = this%bound(1, i)
+      hb = this%head_mult(i)
+      !
       this%xnew(node) = hb
       this%xold(node) = this%xnew(node)
     end do
@@ -204,24 +204,17 @@ subroutine chd_ad(this)
     !    "current" value.
     call this%obs%obs_ad()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine chd_ad
 
+  !> @brief Check constant concentration/temperature boundary condition data
+  !<
   subroutine chd_ck(this)
-! ******************************************************************************
-! chd_ck -- Check chd boundary condition data
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
-    use ConstantsModule, only: LINELENGTH
-    use SimModule, only: store_error, count_errors
     ! -- dummy
     class(ChdType), intent(inout) :: this
     ! -- local
-    character(len=LINELENGTH) :: errmsg
     character(len=30) :: nodestr
     integer(I4B) :: i
     integer(I4B) :: node
@@ -230,36 +223,34 @@ subroutine chd_ck(this)
     character(len=*), parameter :: fmtchderr = &
       "('CHD BOUNDARY ',i0,' HEAD (',g0,') IS LESS THAN CELL &
       &BOTTOM (',g0,')',' FOR CELL ',a)"
-! ------------------------------------------------------------------------------
     !
     ! -- check stress period data
     do i = 1, this%nbound
       node = this%nodelist(i)
       bt = this%dis%bot(node)
       ! -- accumulate errors
-      if (this%bound(1, i) < bt .and. this%icelltype(node) /= 0) then
+      if (this%head_mult(i) < bt .and. this%icelltype(node) /= 0) then
         call this%dis%noder_to_string(node, nodestr)
-        write (errmsg, fmt=fmtchderr) i, this%bound(1, i), bt, trim(nodestr)
+        write (errmsg, fmt=fmtchderr) i, this%head_mult(i), bt, trim(nodestr)
         call store_error(errmsg)
       end if
     end do
     !
-    !write summary of chd package error messages
+    ! write summary of chd package error messages
     if (count_errors() > 0) then
-      call this%parser%StoreErrorUnit()
+      call store_error_filename(this%input_fname)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine chd_ck
 
+  !> @brief Override bnd_fc and do nothing
+  !!
+  !! For constant head boundary type, the call to bnd_fc
+  !! needs to be overwritten to do nothing
+  !<
   subroutine chd_fc(this, rhs, ia, idxglo, matrix_sln)
-! **************************************************************************
-! chd_fc -- Override bnd_fc and do nothing
-! **************************************************************************
-!
-!    SPECIFICATIONS:
-! --------------------------------------------------------------------------
     ! -- dummy
     class(ChdType) :: this
     real(DP), dimension(:), intent(inout) :: rhs
@@ -267,25 +258,31 @@ subroutine chd_fc(this, rhs, ia, idxglo, matrix_sln)
     integer(I4B), dimension(:), intent(in) :: idxglo
     class(MatrixBaseType), pointer :: matrix_sln
     ! -- local
-! --------------------------------------------------------------------------
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine chd_fc
 
+  !> @brief Calculate flow associated with constant head bondary
+  !!
+  !! This method overrides bnd_cq()
+  !<
   subroutine chd_cq(this, x, flowja, iadv)
-! ******************************************************************************
-! chd_cq -- Calculate constant head flow.  This method overrides bnd_cq().
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    ! -- dummy
     class(ChdType), intent(inout) :: this
     real(DP), dimension(:), intent(in) :: x
     real(DP), dimension(:), contiguous, intent(inout) :: flowja
     integer(I4B), optional, intent(in) :: iadv
+
+    ! NB: the rate calculation cannot be done until chd_bd below
+
+  end subroutine chd_cq
+
+  !> @brief Calculate the CHD cell rates, to be called
+  !< after all updates to the model flowja are done
+  subroutine calc_chd_rate(this)
+    ! -- modules
+    ! -- dummy
+    class(ChdType), intent(inout) :: this
     ! -- local
     integer(I4B) :: i
     integer(I4B) :: ipos
@@ -295,7 +292,6 @@ subroutine chd_cq(this, x, flowja, iadv)
     real(DP) :: rate
     real(DP) :: ratein, rateout
     real(DP) :: q
-! ------------------------------------------------------------------------------
     !
     ! -- If no boundaries, skip flow calculations.
     if (this%nbound > 0) then
@@ -311,7 +307,7 @@ subroutine chd_cq(this, x, flowja, iadv)
         ! -- Calculate the flow rate into the cell.
         do ipos = this%dis%con%ia(node) + 1, &
           this%dis%con%ia(node + 1) - 1
-          q = flowja(ipos)
+          q = this%flowja(ipos)
           rate = rate - q
           ! -- only accumulate chin and chout for active
           !    connected cells
@@ -334,16 +330,18 @@ subroutine chd_cq(this, x, flowja, iadv)
         this%simvals(i) = rate
         this%ratechdin(i) = ratein
         this%ratechdout(i) = rateout
-        flowja(idiag) = flowja(idiag) + rate
+        this%flowja(idiag) = this%flowja(idiag) + rate
         !
       end do
       !
     end if
     !
-    ! -- return
+    ! -- Return
     return
-  end subroutine chd_cq
+  end subroutine calc_chd_rate
 
+  !> @brief Add package ratin/ratout to model budget
+  !<
   subroutine chd_bd(this, model_budget)
     ! -- add package ratin/ratout to model budget
     use TdisModule, only: delt
@@ -354,6 +352,13 @@ subroutine chd_bd(this, model_budget)
     real(DP) :: ratout
     real(DP) :: dum
     integer(I4B) :: isuppress_output
+
+    ! For CHDs at an exchange, under some conditions
+    ! (XT3D), the model flowja into the cell is not
+    ! finalized until after exg_cq. So we calculate
+    ! the CHD rate here
+    call this%calc_chd_rate()
+
     isuppress_output = 0
     call rate_accumulator(this%ratechdin(1:this%nbound), ratin, dum)
     call rate_accumulator(this%ratechdout(1:this%nbound), ratout, dum)
@@ -361,40 +366,31 @@ subroutine chd_bd(this, model_budget)
                                isuppress_output, this%packName)
   end subroutine chd_bd
 
+  !> @brief Deallocate memory
+  !<
   subroutine chd_da(this)
-! ******************************************************************************
-! chd_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(ChdType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Deallocate parent package
-    call this%BndType%bnd_da()
+    call this%BndExtType%bnd_da()
     !
     ! -- arrays
     call mem_deallocate(this%ratechdin)
     call mem_deallocate(this%ratechdout)
+    call mem_deallocate(this%head, 'HEAD', this%memoryPath)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine chd_da
 
+  !> @brief Define the list heading that is written to iout when PRINT_INPUT
+  !! option is used.
+  !<
   subroutine define_listlabel(this)
-! ******************************************************************************
-! define_listlabel -- Define the list heading that is written to iout when
-!   PRINT_INPUT option is used.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     class(ChdType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- create the header list label
     this%listlabel = trim(this%filtyp)//' NO.'
@@ -413,73 +409,94 @@ subroutine define_listlabel(this)
       write (this%listlabel, '(a, a16)') trim(this%listlabel), 'BOUNDARY NAME'
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine define_listlabel
 
   ! -- Procedures related to observations
 
+  !> @brief Overrides bnd_obs_supported from bndType class
+  !!
+  !! Return true since CHD package supports observations
+  !<
   logical function chd_obs_supported(this)
-! ******************************************************************************
-! chd_obs_supported
-!   -- Return true because CHD package supports observations.
-!   -- Overrides packagetype%_obs_supported()
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     implicit none
+    !
     class(ChdType) :: this
-! ------------------------------------------------------------------------------
+    !
     chd_obs_supported = .true.
+    !
+    ! -- Return
     return
   end function chd_obs_supported
 
+  !> @brief Overrides bnd_df_obs from bndType class
+  !!
+  !! (1) Store observation type supported by CHD package and (2) override
+  !! BndType%bnd_df_obs
+  !<
   subroutine chd_df_obs(this)
-! ******************************************************************************
-! chd_df_obs (implements bnd_df_obs)
-!   -- Store observation type supported by CHD package.
-!   -- Overrides BndType%bnd_df_obs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     implicit none
     ! -- dummy
     class(ChdType) :: this
     ! -- local
     integer(I4B) :: indx
-! ------------------------------------------------------------------------------
+    !
     call this%obs%StoreObsType('chd', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => DefaultObsIdProcessor
+    !
+    ! -- Return
     return
   end subroutine chd_df_obs
 
-  ! -- Procedure related to time series
+  !> @brief Apply auxiliary multiplier to specified head if appropriate
+  !<
+  function head_mult(this, row) result(head)
+    ! -- modules
+    use ConstantsModule, only: DZERO
+    ! -- dummy variables
+    class(ChdType), intent(inout) :: this !< BndExtType object
+    integer(I4B), intent(in) :: row
+    ! -- result
+    real(DP) :: head
+    !
+    if (this%iauxmultcol > 0) then
+      head = this%head(row) * this%auxvar(this%iauxmultcol, row)
+    else
+      head = this%head(row)
+    end if
+    !
+    ! -- Return
+    return
+  end function head_mult
 
-  subroutine chd_rp_ts(this)
-    ! -- Assign tsLink%Text appropriately for
-    !    all time series in use by package.
-    !    In CHD package variable HEAD
-    !    can be controlled by time series.
-    ! -- dummy
-    class(ChdType), intent(inout) :: this
-    ! -- local
-    integer(I4B) :: i, nlinks
-    type(TimeSeriesLinkType), pointer :: tslink => null()
-    !
-    nlinks = this%TsManager%boundtslinks%Count()
-    do i = 1, nlinks
-      tslink => GetTimeSeriesLinkFromList(this%TsManager%boundtslinks, i)
-      if (associated(tslink)) then
-        select case (tslink%JCol)
-        case (1)
-          tslink%Text = 'HEAD'
-        end select
-      end if
-    end do
+  !> @ brief Return a bound value
+  !!
+  !!  Return a bound value associated with an ncolbnd index
+  !!  and row.
+  !<
+  function chd_bound_value(this, col, row) result(bndval)
+    ! -- modules
+    use ConstantsModule, only: DZERO
+    ! -- dummy variables
+    class(ChdType), intent(inout) :: this !< BndType object
+    integer(I4B), intent(in) :: col
+    integer(I4B), intent(in) :: row
+    ! -- result
+    real(DP) :: bndval
+    !
+    select case (col)
+    case (1)
+      bndval = this%head_mult(row)
+    case default
+      errmsg = 'Programming error. CHD bound value requested column '&
+               &'outside range of ncolbnd (1).'
+      call store_error(errmsg)
+      call store_error_filename(this%input_fname)
+    end select
     !
+    ! -- Return
     return
-  end subroutine chd_rp_ts
+  end function chd_bound_value
 
 end module ChdModule
diff --git a/src/Model/GroundWaterFlow/gwf3chd8idm.f90 b/src/Model/GroundWaterFlow/gwf3chd8idm.f90
new file mode 100644
index 00000000000..78f5c565e44
--- /dev/null
+++ b/src/Model/GroundWaterFlow/gwf3chd8idm.f90
@@ -0,0 +1,430 @@
+! ** Do Not Modify! MODFLOW 6 system generated file. **
+module GwfChdInputModule
+  use ConstantsModule, only: LENVARNAME
+  use InputDefinitionModule, only: InputParamDefinitionType, &
+                                   InputBlockDefinitionType
+  private
+  public gwf_chd_param_definitions
+  public gwf_chd_aggregate_definitions
+  public gwf_chd_block_definitions
+  public GwfChdParamFoundType
+  public gwf_chd_multi_package
+
+  type GwfChdParamFoundType
+    logical :: auxiliary = .false.
+    logical :: auxmultname = .false.
+    logical :: boundnames = .false.
+    logical :: iprpak = .false.
+    logical :: iprflow = .false.
+    logical :: ipakcb = .false.
+    logical :: ts_filerecord = .false.
+    logical :: ts6 = .false.
+    logical :: filein = .false.
+    logical :: ts6_filename = .false.
+    logical :: obs_filerecord = .false.
+    logical :: obs6 = .false.
+    logical :: obs6_filename = .false.
+    logical :: inewton = .false.
+    logical :: maxbound = .false.
+    logical :: cellid = .false.
+    logical :: head = .false.
+    logical :: auxvar = .false.
+    logical :: boundname = .false.
+  end type GwfChdParamFoundType
+
+  logical :: gwf_chd_multi_package = .true.
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_auxiliary = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXILIARY', & ! tag name
+    'AUXILIARY', & ! fortran variable
+    'STRING', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_auxmultname = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXMULTNAME', & ! tag name
+    'AUXMULTNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_boundnames = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'OPTIONS', & ! block
+    'BOUNDNAMES', & ! tag name
+    'BOUNDNAMES', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_iprpak = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_INPUT', & ! tag name
+    'IPRPAK', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_iprflow = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_FLOWS', & ! tag name
+    'IPRFLOW', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_ipakcb = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'OPTIONS', & ! block
+    'SAVE_FLOWS', & ! tag name
+    'IPAKCB', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_ts_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS_FILERECORD', & ! tag name
+    'TS_FILERECORD', & ! fortran variable
+    'RECORD TS6 FILEIN TS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_ts6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS6', & ! tag name
+    'TS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_filein = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'OPTIONS', & ! block
+    'FILEIN', & ! tag name
+    'FILEIN', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_ts6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS6_FILENAME', & ! tag name
+    'TS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_obs_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS_FILERECORD', & ! tag name
+    'OBS_FILERECORD', & ! fortran variable
+    'RECORD OBS6 FILEIN OBS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_obs6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6', & ! tag name
+    'OBS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_obs6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6_FILENAME', & ! tag name
+    'OBS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_inewton = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'OPTIONS', & ! block
+    'DEV_NO_NEWTON', & ! tag name
+    'INEWTON', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_maxbound = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'DIMENSIONS', & ! block
+    'MAXBOUND', & ! tag name
+    'MAXBOUND', & ! fortran variable
+    'INTEGER', & ! type
+    '', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_cellid = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'PERIOD', & ! block
+    'CELLID', & ! tag name
+    'CELLID', & ! fortran variable
+    'INTEGER1D', & ! type
+    'NCELLDIM', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_head = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'PERIOD', & ! block
+    'HEAD', & ! tag name
+    'HEAD', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_auxvar = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'PERIOD', & ! block
+    'AUX', & ! tag name
+    'AUXVAR', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_boundname = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'PERIOD', & ! block
+    'BOUNDNAME', & ! tag name
+    'BOUNDNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_chd_param_definitions(*) = &
+    [ &
+    gwfchd_auxiliary, &
+    gwfchd_auxmultname, &
+    gwfchd_boundnames, &
+    gwfchd_iprpak, &
+    gwfchd_iprflow, &
+    gwfchd_ipakcb, &
+    gwfchd_ts_filerecord, &
+    gwfchd_ts6, &
+    gwfchd_filein, &
+    gwfchd_ts6_filename, &
+    gwfchd_obs_filerecord, &
+    gwfchd_obs6, &
+    gwfchd_obs6_filename, &
+    gwfchd_inewton, &
+    gwfchd_maxbound, &
+    gwfchd_cellid, &
+    gwfchd_head, &
+    gwfchd_auxvar, &
+    gwfchd_boundname &
+    ]
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfchd_spd = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'CHD', & ! subcomponent
+    'PERIOD', & ! block
+    'STRESS_PERIOD_DATA', & ! tag name
+    'SPD', & ! fortran variable
+    'RECARRAY CELLID HEAD AUX BOUNDNAME', & ! type
+    'MAXBOUND', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_chd_aggregate_definitions(*) = &
+    [ &
+    gwfchd_spd &
+    ]
+
+  type(InputBlockDefinitionType), parameter :: &
+    gwf_chd_block_definitions(*) = &
+    [ &
+    InputBlockDefinitionType( &
+    'OPTIONS', & ! blockname
+    .false., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'DIMENSIONS', & ! blockname
+    .true., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'PERIOD', & ! blockname
+    .true., & ! required
+    .true., & ! aggregate
+    .true. & ! block_variable
+    ) &
+    ]
+
+end module GwfChdInputModule
diff --git a/src/Model/GroundWaterFlow/gwf3csub8.f90 b/src/Model/GroundWaterFlow/gwf3csub8.f90
index 8b1c8621e26..db87b8ff411 100644
--- a/src/Model/GroundWaterFlow/gwf3csub8.f90
+++ b/src/Model/GroundWaterFlow/gwf3csub8.f90
@@ -18,7 +18,8 @@ module GwfCsubModule
                              TABLEFT, TABCENTER, TABRIGHT, &
                              TABSTRING, TABUCSTRING, TABINTEGER, TABREAL
   use MemoryHelperModule, only: create_mem_path
-  use GenericUtilitiesModule, only: is_same, sim_message
+  use MathUtilModule, only: is_close
+  use MessageModule, only: write_message
   use SmoothingModule, only: sQuadraticSaturation, &
                              sQuadraticSaturationDerivative, &
                              sQuadratic0sp, &
@@ -29,7 +30,8 @@ module GwfCsubModule
   use BlockParserModule, only: BlockParserType
   use TimeSeriesLinkModule, only: TimeSeriesLinkType, &
                                   GetTimeSeriesLinkFromList
-  use InputOutputModule, only: get_node, extract_idnum_or_bndname
+  use GeomUtilModule, only: get_node
+  use InputOutputModule, only: extract_idnum_or_bndname
   use BaseDisModule, only: DisBaseType
   use SimModule, only: count_errors, store_error, store_error_unit, &
                        store_warning
@@ -247,7 +249,7 @@ module GwfCsubModule
     procedure, private :: csub_read_packagedata
     !
     ! -- helper methods
-    procedure, private :: csub_calc_void
+    procedure, private :: csub_calc_void_ratio
     procedure, private :: csub_calc_theta
     procedure, private :: csub_calc_znode
     procedure, private :: csub_calc_adjes
@@ -1923,7 +1925,7 @@ subroutine csub_fp(this)
         write (msg, '(1x,a,1x,i0,1x,a,1x,i0,1x,a)') &
           'LARGEST', (i1 - i0 + 1), 'OF', this%ninterbeds, &
           'INTERBED STRAIN VALUES SHOWN'
-        call sim_message(msg, this%iout, skipbefore=1)
+        call write_message(msg, this%iout, skipbefore=1)
         !
         ! -- interbed strain data
         ! -- set title
@@ -2113,7 +2115,7 @@ subroutine csub_fp(this)
       write (msg, '(a,1x,i0,1x,a,1x,i0,1x,a)') &
         'LARGEST ', (i1 - i0 + 1), 'OF', this%dis%nodes, &
         'CELL COARSE-GRAINED VALUES SHOWN'
-      call sim_message(msg, this%iout, skipbefore=1)
+      call write_message(msg, this%iout, skipbefore=1)
       !
       ! -- set title
       title = trim(adjustl(this%packName))// &
@@ -2873,7 +2875,7 @@ subroutine csub_fc(this, kiter, hold, hnew, matrix_sln, idxglo, rhs)
           rhs(node) = rhs(node) + rhsterm
           !
           ! -- calculate interbed water compressibility terms
-          if (this%brg /= DZERO .and. idelay == 0) then
+          if (.not. is_close(this%brg, DZERO) .and. idelay == 0) then
             call this%csub_nodelay_wcomp_fc(ib, node, tled, area, &
                                             hnew(node), hold(node), &
                                             hcof, rhsterm)
@@ -3691,10 +3693,14 @@ subroutine csub_ot_dv(this, idvfl, idvprint)
     integer(I4B) :: nodem
     integer(I4B) :: nodeu
     integer(I4B) :: i
+    integer(I4B) :: ii
+    integer(I4B) :: idx_conn
     integer(I4B) :: k
     integer(I4B) :: ncpl
     integer(I4B) :: nlay
+    integer(I4B) :: ihc
     real(DP) :: dinact
+    real(DP) :: va_scale
     ! -- formats
     character(len=*), parameter :: fmtnconv = &
     "(/4x, 'DELAY INTERBED CELL HEADS IN ', i0, ' INTERBEDS IN', &
@@ -3752,7 +3758,26 @@ subroutine csub_ot_dv(this, idvfl, idvprint)
         !
         ! -- disu
         if (this%dis%ndim == 1) then
-          ! TO DO -
+          do node = this%dis%nodes, 1, -1
+            do ii = this%dis%con%ia(node) + 1, this%dis%con%ia(node + 1) - 1
+              !
+              ! -- Set the m cell number
+              nodem = this%dis%con%ja(ii)
+              idx_conn = this%dis%con%jas(ii)
+              !
+              ! -- vertical connection
+              ihc = this%dis%con%ihc(idx_conn)
+              if (ihc == 0) then
+                !
+                ! -- node has an underlying cell
+                if (node < nodem) then
+                  va_scale = this%dis%get_area_factor(node, idx_conn)
+                  this%buffusr(node) = this%buffusr(node) + &
+                                       va_scale * this%buffusr(nodem)
+                end if
+              end if
+            end do
+          end do
           ! -- disv or dis
         else
           nlay = this%dis%nodesuser / ncpl
@@ -3929,7 +3954,7 @@ subroutine csub_cg_calc_stress(this, nodes, hnew)
     integer(I4B) :: ii
     integer(I4B) :: nn
     integer(I4B) :: m
-    integer(I4B) :: iis
+    integer(I4B) :: idx_conn
     real(DP) :: gs
     real(DP) :: top
     real(DP) :: bot
@@ -3938,11 +3963,8 @@ subroutine csub_cg_calc_stress(this, nodes, hnew)
     real(DP) :: hcell
     real(DP) :: hbar
     real(DP) :: gs_conn
-    real(DP) :: area_node
-    real(DP) :: area_conn
     real(DP) :: es
     real(DP) :: phead
-    real(DP) :: hwva
     real(DP) :: sadd
     !
     ! -- calculate geostatic stress if necessary
@@ -3986,9 +4008,6 @@ subroutine csub_cg_calc_stress(this, nodes, hnew)
       !
       ! -- calculate geostatic stress above cell
       do node = 1, this%dis%nodes
-        !
-        ! -- area of cell
-        area_node = this%dis%get_area(node)
         !
         ! -- geostatic stress of cell
         gs = this%cg_gs(node)
@@ -3999,10 +4018,10 @@ subroutine csub_cg_calc_stress(this, nodes, hnew)
           !
           ! -- Set the m cell number
           m = this%dis%con%ja(ii)
-          iis = this%dis%con%jas(ii)
+          idx_conn = this%dis%con%jas(ii)
           !
           ! -- vertical connection
-          if (this%dis%con%ihc(iis) == 0) then
+          if (this%dis%con%ihc(idx_conn) == 0) then
             !
             ! -- node has an overlying cell
             if (m < node) then
@@ -4012,15 +4031,11 @@ subroutine csub_cg_calc_stress(this, nodes, hnew)
                 gs = gs + this%cg_gs(m)
                 !
                 ! -- disu discretization
-                !    *** this needs to be checked ***
               else
-                area_conn = this%dis%get_area(m)
-                hwva = this%dis%con%hwva(iis)
-                va_scale = this%dis%con%hwva(iis) / this%dis%get_area(m)
+                va_scale = this%dis%get_area_factor(node, idx_conn)
                 gs_conn = this%cg_gs(m)
                 gs = gs + (gs_conn * va_scale)
               end if
-
             end if
           end if
         end do
@@ -4356,7 +4371,7 @@ subroutine csub_set_initial_state(this, nodes, hnew)
     real(DP) :: fact
     real(DP) :: top
     real(DP) :: bot
-    real(DP) :: void
+    real(DP) :: void_ratio
     real(DP) :: es
     real(DP) :: znode
     real(DP) :: hcell
@@ -4450,7 +4465,7 @@ subroutine csub_set_initial_state(this, nodes, hnew)
           ! -- convert specific storage values since they are simulated to
           !    be a function of the average effective stress
         else
-          void = this%csub_calc_void(this%cg_theta(node))
+          void_ratio = this%csub_calc_void_ratio(this%cg_theta(node))
           es = this%cg_es(node)
           hcell = hnew(node)
           !
@@ -4460,7 +4475,7 @@ subroutine csub_set_initial_state(this, nodes, hnew)
           ! -- calculate znode and factor
           znode = this%csub_calc_znode(top, bot, hbar)
           fact = this%csub_calc_adjes(node, es, bot, znode)
-          fact = fact * (DONE + void)
+          fact = fact * (DONE + void_ratio)
         end if
         !
         ! -- user-specified compression indices - multiply by dlog10es
@@ -4496,7 +4511,7 @@ subroutine csub_set_initial_state(this, nodes, hnew)
           ! -- convert specific storage values since they are simulated to
           !    be a function of the average effective stress
         else
-          void = this%csub_calc_void(this%theta(ib))
+          void_ratio = this%csub_calc_void_ratio(this%theta(ib))
           es = this%cg_es(node)
           hcell = hnew(node)
           !
@@ -4506,7 +4521,7 @@ subroutine csub_set_initial_state(this, nodes, hnew)
           ! -- calculate zone and factor
           znode = this%csub_calc_znode(top, bot, hbar)
           fact = this%csub_calc_adjes(node, es, bot, znode)
-          fact = fact * (DONE + void)
+          fact = fact * (DONE + void_ratio)
         end if
         !
         ! -- user-specified compression indices - multiply by dlog10es
@@ -5426,18 +5441,18 @@ end subroutine csub_nodelay_wcomp_fn
   !!
   !! @return      void                void ratio
   !<
-  function csub_calc_void(this, theta) result(void)
+  function csub_calc_void_ratio(this, theta) result(void_ratio)
     ! -- dummy variables
     class(GwfCsubType), intent(inout) :: this
     real(DP), intent(in) :: theta !< porosity
     ! -- local variables
-    real(DP) :: void
+    real(DP) :: void_ratio
     ! -- calculate void ratio
-    void = theta / (DONE - theta)
+    void_ratio = theta / (DONE - theta)
     !
     ! -- return
     return
-  end function csub_calc_void
+  end function csub_calc_void_ratio
 
   !> @brief Calculate the porosity
   !!
@@ -5445,15 +5460,15 @@ end function csub_calc_void
   !!
   !! @return      theta               porosity
   !<
-  function csub_calc_theta(this, void) result(theta)
+  function csub_calc_theta(this, void_ratio) result(theta)
     ! -- dummy variables
     class(GwfCsubType), intent(inout) :: this
-    real(DP), intent(in) :: void
+    real(DP), intent(in) :: void_ratio
     ! -- local variables
     real(DP) :: theta
     !
     ! -- calculate theta
-    theta = void / (DONE + void)
+    theta = void_ratio / (DONE + void_ratio)
     !
     ! -- return
     return
@@ -5678,10 +5693,10 @@ subroutine csub_calc_sfacts(this, node, bot, znode, theta, es, es0, fact)
     real(DP), intent(in) :: theta !< porosity
     real(DP), intent(in) :: es !< current effective stress
     real(DP), intent(in) :: es0 !< previous effective stress
-    real(DP), intent(inout) :: fact !< skeletal storage coefficient factor (1/((1+void)*bar(es)))
+    real(DP), intent(inout) :: fact !< skeletal storage coefficient factor (1/((1+void_ratio)*bar(es)))
     ! -- local variables
     real(DP) :: esv
-    real(DP) :: void
+    real(DP) :: void_ratio
     real(DP) :: denom
     !
     ! -- initialize variables
@@ -5693,9 +5708,9 @@ subroutine csub_calc_sfacts(this, node, bot, znode, theta, es, es0, fact)
     end if
     !
     ! -- calculate storage factors for the effective stress case
-    void = this%csub_calc_void(theta)
+    void_ratio = this%csub_calc_void_ratio(theta)
     denom = this%csub_calc_adjes(node, esv, bot, znode)
-    denom = denom * (DONE + void)
+    denom = denom * (DONE + void_ratio)
     if (denom /= DZERO) then
       fact = DONE / denom
     end if
@@ -5720,18 +5735,18 @@ subroutine csub_adj_matprop(this, comp, thick, theta)
     real(DP), intent(inout) :: theta !< porosity
     ! -- local variables
     real(DP) :: strain
-    real(DP) :: void
+    real(DP) :: void_ratio
     !
     ! -- initialize variables
     strain = DZERO
-    void = this%csub_calc_void(theta)
+    void_ratio = this%csub_calc_void_ratio(theta)
     !
     ! -- calculate strain
     if (thick > DZERO) strain = -comp / thick
     !
     ! -- update void ratio, theta, and thickness
-    void = void + strain * (DONE + void)
-    theta = this%csub_calc_theta(void)
+    void_ratio = void_ratio + strain * (DONE + void_ratio)
+    theta = this%csub_calc_theta(void_ratio)
     thick = thick - comp
     !
     ! -- return
diff --git a/src/Model/GroundWaterFlow/gwf3dis8.f90 b/src/Model/GroundWaterFlow/gwf3dis8.f90
index f13f34ee9f9..5ddb0adb81b 100644
--- a/src/Model/GroundWaterFlow/gwf3dis8.f90
+++ b/src/Model/GroundWaterFlow/gwf3dis8.f90
@@ -1,15 +1,20 @@
 module GwfDisModule
 
   use ArrayReadersModule, only: ReadArray
-  use KindModule, only: DP, I4B
-  use ConstantsModule, only: LINELENGTH, DHALF, DZERO, LENMEMPATH, LENVARNAME
+  use KindModule, only: DP, I4B, LGP
+  use ConstantsModule, only: LINELENGTH, DHALF, DONE, DZERO, &
+                             LENMEMPATH, LENVARNAME
   use BaseDisModule, only: DisBaseType
-  use InputOutputModule, only: get_node, URWORD, ulasav, ulaprufw, ubdsv1, &
-                               ubdsv06
+  use GeomUtilModule, only: get_node, get_ijk
+  use InputOutputModule, only: URWORD, ulasav, ulaprufw, &
+                               ubdsv1, ubdsv06, urword, getunit, openfile
   use SimModule, only: count_errors, store_error, store_error_unit, &
                        store_error_filename
-  use MemoryManagerModule, only: mem_allocate
+  use SimVariablesModule, only: errmsg, idm_context
+  use MemoryManagerModule, only: mem_allocate, mem_deallocate
+  use MemoryManagerExtModule, only: mem_set_value, memorylist_remove
   use TdisModule, only: kstp, kper, pertim, totim, delt
+  use GwfDisInputModule, only: GwfDisParamFoundType
 
   implicit none
   private
@@ -27,7 +32,9 @@ module GwfDisModule
     real(DP), dimension(:, :, :), pointer :: botm => null() ! top and bottom elevations for each cell (ncol, nrow, nlay)
     real(DP), dimension(:), pointer, contiguous :: cellx => null() ! cell center x coordinate for column j
     real(DP), dimension(:), pointer, contiguous :: celly => null() ! cell center y coordinate for row i
+
   contains
+
     procedure :: dis_df => dis3d_df
     procedure :: dis_da => dis3d_da
     procedure :: get_dis_type => get_dis_type
@@ -44,6 +51,7 @@ module GwfDisModule
     procedure :: nodeu_from_cellid
     procedure :: supports_layers
     procedure :: get_ncpl
+    procedure :: get_polyverts
     procedure :: connection_vector
     procedure :: connection_normal
     ! -- private
@@ -65,16 +73,9 @@ module GwfDisModule
 
 contains
 
+  !> @brief Create a new structured discretization object
+  !<
   subroutine dis_cr(dis, name_model, input_mempath, inunit, iout)
-! ******************************************************************************
-! dis_cr -- Create a new discretization 3d object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use KindModule, only: LGP
-    use MemoryManagerExtModule, only: mem_set_value
     ! -- dummy
     class(DisBaseType), pointer :: dis
     character(len=*), intent(in) :: name_model
@@ -83,22 +84,17 @@ subroutine dis_cr(dis, name_model, input_mempath, inunit, iout)
     integer(I4B), intent(in) :: iout
     ! -- locals
     type(GwfDisType), pointer :: disnew
-    logical(LGP) :: found_fname
+    ! -- formats
     character(len=*), parameter :: fmtheader = &
       "(1X, /1X, 'DIS -- STRUCTURED GRID DISCRETIZATION PACKAGE,', &
       &' VERSION 2 : 3/27/2014 - INPUT READ FROM MEMPATH: ', A, /)"
-! ------------------------------------------------------------------------------
+    !
     allocate (disnew)
     dis => disnew
-    call disnew%allocate_scalars(name_model)
-    dis%input_mempath = input_mempath
+    call disnew%allocate_scalars(name_model, input_mempath)
     dis%inunit = inunit
     dis%iout = iout
     !
-    ! -- set name of input file
-    call mem_set_value(dis%input_fname, 'INPUT_FNAME', dis%input_mempath, &
-                       found_fname)
-    !
     ! -- If dis enabled
     if (inunit > 0) then
       !
@@ -108,22 +104,14 @@ subroutine dis_cr(dis, name_model, input_mempath, inunit, iout)
       end if
     end if
     !
-    ! -- Return
-    return
   end subroutine dis_cr
 
+  !> @brief Define the discretization
+  !<
   subroutine dis3d_df(this)
-! ******************************************************************************
-! dis3d_df -- Define
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfDisType) :: this
-    ! -- locals
-! ------------------------------------------------------------------------------
+    !
     ! -- Transfer the data from the memory manager into this package object
     if (this%inunit /= 0) then
       !
@@ -140,25 +128,13 @@ subroutine dis3d_df(this)
     ! -- Final grid initialization
     call this%grid_finalize()
     !
-    ! -- Return
-    return
   end subroutine dis3d_df
 
+  !> @brief Deallocate variables
+  !<
   subroutine dis3d_da(this)
-! ******************************************************************************
-! dis3d_da -- Deallocate discretization data
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_deallocate
-    use MemoryManagerExtModule, only: memorylist_remove
-    use SimVariablesModule, only: idm_context
     ! -- dummy
     class(GwfDisType) :: this
-    ! -- locals
-! ------------------------------------------------------------------------------
     !
     ! -- Deallocate idm memory
     call memorylist_remove(this%name_model, 'DIS', idm_context)
@@ -182,16 +158,11 @@ subroutine dis3d_da(this)
     call mem_deallocate(this%bot3d)
     call mem_deallocate(this%idomain)
     !
-    ! -- Return
-    return
   end subroutine dis3d_da
 
   !> @brief Copy options from IDM into package
   !<
   subroutine source_options(this)
-    ! -- modules
-    use MemoryManagerExtModule, only: mem_set_value
-    use GwfDisInputModule, only: GwfDisParamFoundType
     ! -- dummy
     class(GwfDisType) :: this
     ! -- locals
@@ -212,50 +183,46 @@ subroutine source_options(this)
       call this%log_options(found)
     end if
     !
-    ! -- Return
-    return
   end subroutine source_options
 
   !> @brief Write user options to list file
   !<
   subroutine log_options(this, found)
-    use GwfDisInputModule, only: GwfDisParamFoundType
+    ! -- dummy
     class(GwfDisType) :: this
     type(GwfDisParamFoundType), intent(in) :: found
-
+    !
     write (this%iout, '(1x,a)') 'Setting Discretization Options'
-
+    !
     if (found%length_units) then
       write (this%iout, '(4x,a,i0)') 'Model length unit [0=UND, 1=FEET, &
       &2=METERS, 3=CENTIMETERS] set as ', this%lenuni
     end if
-
+    !
     if (found%nogrb) then
       write (this%iout, '(4x,a,i0)') 'Binary grid file [0=GRB, 1=NOGRB] &
         &set as ', this%nogrb
     end if
-
+    !
     if (found%xorigin) then
       write (this%iout, '(4x,a,G0)') 'XORIGIN = ', this%xorigin
     end if
-
+    !
     if (found%yorigin) then
       write (this%iout, '(4x,a,G0)') 'YORIGIN = ', this%yorigin
     end if
-
+    !
     if (found%angrot) then
       write (this%iout, '(4x,a,G0)') 'ANGROT = ', this%angrot
     end if
-
+    !
     write (this%iout, '(1x,a,/)') 'End Setting Discretization Options'
-
+    !
   end subroutine log_options
 
   !> @brief Copy dimensions from IDM into package
   !<
   subroutine source_dimensions(this)
-    use MemoryManagerExtModule, only: mem_set_value
-    use GwfDisInputModule, only: GwfDisParamFoundType
     ! -- dummy
     class(GwfDisType) :: this
     ! -- locals
@@ -312,51 +279,39 @@ subroutine source_dimensions(this)
       end do
     end do
     !
-    ! -- Return
-    return
   end subroutine source_dimensions
 
   !> @brief Write dimensions to list file
   !<
   subroutine log_dimensions(this, found)
-    use GwfDisInputModule, only: GwfDisParamFoundType
+    ! -- dummy
     class(GwfDisType) :: this
     type(GwfDisParamFoundType), intent(in) :: found
-
+    !
     write (this%iout, '(1x,a)') 'Setting Discretization Dimensions'
-
+    !
     if (found%nlay) then
       write (this%iout, '(4x,a,i0)') 'NLAY = ', this%nlay
     end if
-
+    !
     if (found%nrow) then
       write (this%iout, '(4x,a,i0)') 'NROW = ', this%nrow
     end if
-
+    !
     if (found%ncol) then
       write (this%iout, '(4x,a,i0)') 'NCOL = ', this%ncol
     end if
-
+    !
     write (this%iout, '(1x,a,/)') 'End Setting Discretization Dimensions'
-
+    !
   end subroutine log_dimensions
 
+  !> @brief Copy grid data from IDM into package
+  !<
   subroutine source_griddata(this)
-! ******************************************************************************
-! source_griddata -- update simulation mempath griddata
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerExtModule, only: mem_set_value
-    use GwfDisInputModule, only: GwfDisParamFoundType
     ! -- dummy
     class(GwfDisType) :: this
-    ! -- locals
     type(GwfDisParamFoundType) :: found
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- update defaults with idm sourced values
     call mem_set_value(this%delr, 'DELR', this%input_mempath, found%delr)
@@ -370,57 +325,49 @@ subroutine source_griddata(this)
       call this%log_griddata(found)
     end if
     !
-    ! -- Return
-    return
   end subroutine source_griddata
 
   !> @brief Write dimensions to list file
   !<
   subroutine log_griddata(this, found)
-    use GwfDisInputModule, only: GwfDisParamFoundType
+    ! -- dummy
     class(GwfDisType) :: this
     type(GwfDisParamFoundType), intent(in) :: found
-
+    !
     write (this%iout, '(1x,a)') 'Setting Discretization Griddata'
-
+    !
     if (found%delr) then
       write (this%iout, '(4x,a)') 'DELR set from input file'
     end if
-
+    !
     if (found%delc) then
       write (this%iout, '(4x,a)') 'DELC set from input file'
     end if
-
+    !
     if (found%top) then
       write (this%iout, '(4x,a)') 'TOP set from input file'
     end if
-
+    !
     if (found%botm) then
       write (this%iout, '(4x,a)') 'BOTM set from input file'
     end if
-
+    !
     if (found%idomain) then
       write (this%iout, '(4x,a)') 'IDOMAIN set from input file'
     end if
-
+    !
     write (this%iout, '(1x,a,/)') 'End Setting Discretization Griddata'
-
+    !
   end subroutine log_griddata
 
+  !> @brief Finalize grid (check properties, allocate arrays, compute connections)
+  !<
   subroutine grid_finalize(this)
-! ******************************************************************************
-! grid_finalize -- Finalize grid
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
-    use ConstantsModule, only: LINELENGTH, DZERO
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwfDisType) :: this
     ! -- locals
-    character(len=300) :: ermsg
     integer(I4B) :: n, i, j, k
     integer(I4B) :: node
     integer(I4B) :: noder
@@ -435,7 +382,6 @@ subroutine grid_finalize(this)
       "(/1x, 'The specified IDOMAIN results in a reduced number of cells.',&
       &/1x, 'Number of user nodes: ',I0,&
       &/1X, 'Number of nodes in solution: ', I0, //)"
-! ------------------------------------------------------------------------------
     !
     ! -- count active cells
     this%nodes = 0
@@ -469,8 +415,8 @@ subroutine grid_finalize(this)
           dz = top - this%bot3d(j, i, k)
           if (dz <= DZERO) then
             n = n + 1
-            write (ermsg, fmt=fmtdz) k, i, j, top, this%bot3d(j, i, k)
-            call store_error(ermsg)
+            write (errmsg, fmt=fmtdz) k, i, j, top, this%bot3d(j, i, k)
+            call store_error(errmsg)
           end if
         end do
       end do
@@ -576,21 +522,13 @@ subroutine grid_finalize(this)
     this%nja = this%con%nja
     this%njas = this%con%njas
     !
-    ! -- Return
-    return
   end subroutine grid_finalize
 
+  !> @brief Write a binary grid file
+  !<
   subroutine write_grb(this, icelltype)
-! ******************************************************************************
-! write_grb -- Write the binary grid file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
-    use InputOutputModule, only: getunit, openfile
     use OpenSpecModule, only: access, form
-    use ConstantsModule, only: DZERO
     ! -- dummy
     class(GwfDisType) :: this
     integer(I4B), dimension(:), intent(in) :: icelltype
@@ -603,7 +541,6 @@ subroutine write_grb(this, icelltype)
     character(len=*), parameter :: fmtgrdsave = &
       "(4X,'BINARY GRID INFORMATION WILL BE WRITTEN TO:', &
        &/,6X,'UNIT NUMBER: ', I0,/,6X, 'FILE NAME: ', A)"
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize
     ntxt = 16
@@ -701,27 +638,18 @@ subroutine write_grb(this, icelltype)
     ! -- Close the file
     close (iunit)
     !
-    ! -- return
-    return
   end subroutine write_grb
 
+  !> @brief Convert a user nodenumber to a string (nodenumber) or (k,i,j)
+  !<
   subroutine nodeu_to_string(this, nodeu, str)
-! ******************************************************************************
-! nodeu_to_string -- Convert user node number to a string in the form of
-! (nodenumber) or (k,i,j)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use InputOutputModule, only: get_ijk
-    implicit none
+    ! -- dummy
     class(GwfDisType) :: this
     integer(I4B), intent(in) :: nodeu
     character(len=*), intent(inout) :: str
     ! -- local
     integer(I4B) :: i, j, k
     character(len=10) :: kstr, istr, jstr
-! ------------------------------------------------------------------------------
     !
     call get_ijk(nodeu, this%nrow, this%ncol, this%nlay, i, j, k)
     write (kstr, '(i10)') k
@@ -731,28 +659,18 @@ subroutine nodeu_to_string(this, nodeu, str)
           trim(adjustl(istr))//','// &
           trim(adjustl(jstr))//')'
     !
-    ! -- return
-    return
   end subroutine nodeu_to_string
 
+  !> @brief Convert a user nodenumber to an array (nodenumber) or (k,i,j)
+  !<
   subroutine nodeu_to_array(this, nodeu, arr)
-! ******************************************************************************
-! nodeu_to_array -- Convert user node number to cellid and fill array with
-!                   (nodenumber) or (k,j) or (k,i,j)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use InputOutputModule, only: get_ijk
-    implicit none
+    ! -- dummy
     class(GwfDisType) :: this
     integer(I4B), intent(in) :: nodeu
     integer(I4B), dimension(:), intent(inout) :: arr
     ! -- local
-    character(len=LINELENGTH) :: errmsg
     integer(I4B) :: isize
     integer(I4B) :: i, j, k
-! ------------------------------------------------------------------------------
     !
     ! -- check the size of arr
     isize = size(arr)
@@ -771,37 +689,26 @@ subroutine nodeu_to_array(this, nodeu, arr)
     arr(2) = i
     arr(3) = j
     !
-    ! -- return
-    return
   end subroutine nodeu_to_array
 
+  !> @brief Get reduced node number from user node number
+  !<
   function get_nodenumber_idx1(this, nodeu, icheck) result(nodenumber)
-! ******************************************************************************
-! get_nodenumber -- Return a nodenumber from the user specified node number
-!                   with an option to perform a check.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use ConstantsModule, only: LINELENGTH
     ! -- return
     integer(I4B) :: nodenumber
     ! -- dummy
     class(GwfDisType), intent(in) :: this
     integer(I4B), intent(in) :: nodeu
     integer(I4B), intent(in) :: icheck
-    ! -- local
-    character(len=LINELENGTH) :: errmsg
-! ------------------------------------------------------------------------------
     !
     ! -- check the node number if requested
     if (icheck /= 0) then
       !
       ! -- If within valid range, convert to reduced nodenumber
       if (nodeu < 1 .or. nodeu > this%nodesuser) then
-        write (errmsg, '(a,i10)') &
-          'Nodenumber less than 1 or greater than nodes:', nodeu
+        write (errmsg, '(a,i0,a)') &
+          'Node number (', nodeu, &
+          ') less than 1 or greater than the number of nodes.'
         call store_error(errmsg)
         nodenumber = 0
       else
@@ -813,22 +720,11 @@ function get_nodenumber_idx1(this, nodeu, icheck) result(nodenumber)
       if (this%nodes < this%nodesuser) nodenumber = this%nodereduced(nodeu)
     end if
     !
-    ! -- return
-    return
   end function get_nodenumber_idx1
 
-  function get_nodenumber_idx3(this, k, i, j, icheck) &
-    result(nodenumber)
-! ******************************************************************************
-! get_nodenumber_idx3 -- Return a nodenumber from the user specified layer, row,
-!                        and column with an option to perform a check.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use ConstantsModule, only: LINELENGTH
-    use InputOutputModule, only: get_node
-    implicit none
+  !> @brief Get reduced node number from layer, row and column indices
+  !<
+  function get_nodenumber_idx3(this, k, i, j, icheck) result(nodenumber)
     ! -- return
     integer(I4B) :: nodenumber
     ! -- dummy
@@ -836,13 +732,11 @@ function get_nodenumber_idx3(this, k, i, j, icheck) &
     integer(I4B), intent(in) :: k, i, j
     integer(I4B), intent(in) :: icheck
     ! -- local
-    character(len=LINELENGTH) :: errmsg
     integer(I4B) :: nodeu
     ! formats
     character(len=*), parameter :: fmterr = &
       "('Error in structured-grid cell indices: layer = ',i0,', &
       &row = ',i0,', column = ',i0)"
-! ------------------------------------------------------------------------------
     !
     nodeu = get_node(k, i, j, this%nlay, this%nrow, this%ncol)
     if (nodeu < 1) then
@@ -864,31 +758,24 @@ function get_nodenumber_idx3(this, k, i, j, icheck) &
       !
       ! -- Error if outside of range
       if (nodeu < 1 .or. nodeu > this%nodesuser) then
-        write (errmsg, '(a,i10)') &
-          'Nodenumber less than 1 or greater than nodes:', nodeu
+        write (errmsg, '(a,i0,a)') &
+          'Node number (', nodeu, ')less than 1 or greater than nodes.'
         call store_error(errmsg)
       end if
     end if
     !
-    ! -- return
-    return
   end function get_nodenumber_idx3
 
-  subroutine allocate_scalars(this, name_model)
-! ******************************************************************************
-! allocate_scalars -- Allocate and initialize scalars
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
+  !> @brief Allocate and initialize scalar variables
+  !<
+  subroutine allocate_scalars(this, name_model, input_mempath)
     ! -- dummy
     class(GwfDisType) :: this
     character(len=*), intent(in) :: name_model
-! ------------------------------------------------------------------------------
+    character(len=*), intent(in) :: input_mempath
     !
     ! -- Allocate parent scalars
-    call this%DisBaseType%allocate_scalars(name_model)
+    call this%DisBaseType%allocate_scalars(name_model, input_mempath)
     !
     ! -- Allocate
     call mem_allocate(this%nlay, 'NLAY', this%memoryPath)
@@ -901,22 +788,13 @@ subroutine allocate_scalars(this, name_model)
     this%ncol = 0
     this%ndim = 3
     !
-    ! -- Return
-    return
   end subroutine allocate_scalars
 
+  !> @brief Allocate and initialize arrays
+  !<
   subroutine allocate_arrays(this)
-! ******************************************************************************
-! allocate_arrays -- Allocate arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwfDisType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate arrays in DisBaseType (mshape, top, bot, area)
     call this%DisBaseType%allocate_arrays()
@@ -936,22 +814,16 @@ subroutine allocate_arrays(this)
     this%mshape(2) = this%nrow
     this%mshape(3) = this%ncol
     !
-    ! -- Return
-    return
   end subroutine allocate_arrays
 
+  !> @brief Convert a string to a user nodenumber
+  !!
+  !! Parse layer, row and column and return user nodenumber.
+  !! If flag_string is present and true, the first token may be
+  !! non-numeric (e.g. boundary name). In this case, return -2.
+  !<
   function nodeu_from_string(this, lloc, istart, istop, in, iout, line, &
                              flag_string, allow_zero) result(nodeu)
-! ******************************************************************************
-! nodeu_from_string -- Receive a string and convert the string to a user
-!   nodenumber.  The model discretization is DIS; read layer, row, and column.
-!   If flag_string argument is present and true, the first token in string
-!   is allowed to be a string (e.g. boundary name). In this case, if a string
-!   is encountered, return value as -2.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfDisType) :: this
     integer(I4B), intent(inout) :: lloc
@@ -967,8 +839,6 @@ function nodeu_from_string(this, lloc, istart, istop, in, iout, line, &
     integer(I4B) :: k, i, j, nlay, nrow, ncol
     integer(I4B) :: lloclocal, ndum, istat, n
     real(DP) :: r
-    character(len=LINELENGTH) :: ermsg, fname
-! ------------------------------------------------------------------------------
     !
     if (present(flag_string)) then
       if (flag_string) then
@@ -1001,51 +871,50 @@ function nodeu_from_string(this, lloc, istart, istop, in, iout, line, &
       end if
     end if
     !
+    errmsg = ""
+    !
     if (k < 1 .or. k > nlay) then
-      write (ermsg, *) ' Layer number in list is outside of the grid', k
-      call store_error(ermsg)
+      write (errmsg, '(a,i0,a)') &
+        'Layer number in list (', k, ') is outside of the grid.'
     end if
     if (i < 1 .or. i > nrow) then
-      write (ermsg, *) ' Row number in list is outside of the grid', i
-      call store_error(ermsg)
+      write (errmsg, '(a,1x,a,i0,a)') &
+        trim(adjustl(errmsg)), 'Row number in list (', i, &
+        ') is outside of the grid.'
     end if
     if (j < 1 .or. j > ncol) then
-      write (ermsg, *) ' Column number in list is outside of the grid', j
-      call store_error(ermsg)
+      write (errmsg, '(a,1x,a,i0,a)') &
+        trim(adjustl(errmsg)), 'Column number in list (', j, &
+        ') is outside of the grid.'
     end if
+    !
     nodeu = get_node(k, i, j, nlay, nrow, ncol)
     !
     if (nodeu < 1 .or. nodeu > this%nodesuser) then
-      write (ermsg, *) ' Node number in list is outside of the grid', nodeu
-      call store_error(ermsg)
-      inquire (unit=in, name=fname)
-      call store_error('Error converting in file: ')
-      call store_error(trim(adjustl(fname)))
-      call store_error('Cell number cannot be determined in line: ')
-      call store_error(trim(adjustl(line)))
+      write (errmsg, '(a,1x,a,i0,a)') &
+        trim(adjustl(errmsg)), &
+        "Node number in list (", nodeu, ") is outside of the grid. "// &
+        "Cell number cannot be determined in line '"// &
+        trim(adjustl(line))//"'."
+    end if
+    !
+    if (len_trim(adjustl(errmsg)) > 0) then
+      call store_error(errmsg)
       call store_error_unit(in)
     end if
     !
-    ! -- return
-    return
-
   end function nodeu_from_string
 
+  !> @brief Convert a cellid string to a user nodenumber
+  !!
+  !! If flag_string is present and true, the first token may be
+  !! non-numeric (e.g. boundary name). In this case, return -2.
+  !!
+  !! If allow_zero is present and true, and all indices are zero, the
+  !! result can be zero. If allow_zero is false, a zero in any index is an error.
+  !<
   function nodeu_from_cellid(this, cellid, inunit, iout, flag_string, &
                              allow_zero) result(nodeu)
-! ******************************************************************************
-! nodeu_from_cellid -- Receive cellid as a string and convert the string to a
-!   user nodenumber.
-!   If flag_string argument is present and true, the first token in string
-!   is allowed to be a string (e.g. boundary name). In this case, if a string
-!   is encountered, return value as -2.
-!   If allow_zero argument is present and true, if all indices equal zero, the
-!   result can be zero. If allow_zero is false, a zero in any index causes an
-!   error.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     integer(I4B) :: nodeu
     ! -- dummy
@@ -1060,8 +929,6 @@ function nodeu_from_cellid(this, cellid, inunit, iout, flag_string, &
     integer(I4B) :: k, i, j, nlay, nrow, ncol
     integer(I4B) :: istat
     real(DP) :: r
-    character(len=LINELENGTH) :: ermsg, fname
-! ------------------------------------------------------------------------------
     !
     if (present(flag_string)) then
       if (flag_string) then
@@ -1095,84 +962,69 @@ function nodeu_from_cellid(this, cellid, inunit, iout, flag_string, &
       end if
     end if
     !
+    errmsg = ""
+    !
     if (k < 1 .or. k > nlay) then
-      write (ermsg, *) ' Layer number in list is outside of the grid', k
-      call store_error(ermsg)
+      write (errmsg, '(a,i0,a)') &
+        'Layer number in list (', k, ') is outside of the grid.'
     end if
     if (i < 1 .or. i > nrow) then
-      write (ermsg, *) ' Row number in list is outside of the grid', i
-      call store_error(ermsg)
+      write (errmsg, '(a,1x,a,i0,a)') &
+        trim(adjustl(errmsg)), 'Row number in list (', i, &
+        ') is outside of the grid.'
     end if
     if (j < 1 .or. j > ncol) then
-      write (ermsg, *) ' Column number in list is outside of the grid', j
-      call store_error(ermsg)
+      write (errmsg, '(a,1x,a,i0,a)') &
+        trim(adjustl(errmsg)), 'Column number in list (', j, &
+        ') is outside of the grid.'
     end if
+    !
     nodeu = get_node(k, i, j, nlay, nrow, ncol)
     !
     if (nodeu < 1 .or. nodeu > this%nodesuser) then
-      write (ermsg, *) ' Node number in list is outside of the grid', nodeu
-      call store_error(ermsg)
-      inquire (unit=inunit, name=fname)
-      call store_error('Error converting in file: ')
-      call store_error(trim(adjustl(fname)))
-      call store_error('Cell number cannot be determined in cellid: ')
-      call store_error(trim(adjustl(cellid)))
+      write (errmsg, '(a,1x,a,i0,a)') &
+        trim(adjustl(errmsg)), &
+        "Cell number cannot be determined for cellid ("// &
+        trim(adjustl(cellid))//") and results in a user "// &
+        "node number (", nodeu, ") that is outside of the grid."
+    end if
+    !
+    if (len_trim(adjustl(errmsg)) > 0) then
+      call store_error(errmsg)
       call store_error_unit(inunit)
     end if
     !
-    ! -- return
-    return
   end function nodeu_from_cellid
 
+  !> @brief Indicates whether the grid discretization supports layers
+  !<
   logical function supports_layers(this)
-    implicit none
     ! -- dummy
     class(GwfDisType) :: this
     !
     supports_layers = .true.
-    return
+    !
   end function supports_layers
 
+  !> @brief Return number of cells per layer (nrow * ncol)
+  !<
   function get_ncpl(this)
-! ******************************************************************************
-! get_ncpl -- Return number of cells per layer.  This is nrow * ncol
-!   for a DIS3D grid.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    ! -- return
     integer(I4B) :: get_ncpl
-    ! -- dummy
     class(GwfDisType) :: this
-! ------------------------------------------------------------------------------
-    !
     get_ncpl = this%nrow * this%ncol
-    !
-    ! -- Return
-    return
   end function get_ncpl
 
+  !> @brief Get normal vector components between the cell and a given neighbor
+  !!
+  !! The normal points outward from the shared face between noden and nodem.
+  !<
   subroutine connection_normal(this, noden, nodem, ihc, xcomp, ycomp, zcomp, &
                                ipos)
-! ******************************************************************************
-! connection_normal -- calculate the normal vector components for reduced
-!   nodenumber cell (noden) and its shared face with cell nodem.  ihc is the
-!   horizontal connection flag.  Connection normal is a normal vector pointing
-!   outward from the shared face between noden and nodem.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use ConstantsModule, only: DZERO, DONE
-    use InputOutputModule, only: get_ijk
     ! -- dummy
     class(GwfDisType) :: this
-    integer(I4B), intent(in) :: noden
-    integer(I4B), intent(in) :: nodem
-    integer(I4B), intent(in) :: ihc
+    integer(I4B), intent(in) :: noden !< cell (reduced nn)
+    integer(I4B), intent(in) :: nodem !< neighbor (reduced nn)
+    integer(I4B), intent(in) :: ihc !< horizontal connection flag
     real(DP), intent(inout) :: xcomp
     real(DP), intent(inout) :: ycomp
     real(DP), intent(inout) :: zcomp
@@ -1180,7 +1032,6 @@ subroutine connection_normal(this, noden, nodem, ihc, xcomp, ycomp, zcomp, &
     ! -- local
     integer(I4B) :: nodeu1, i1, j1, k1
     integer(I4B) :: nodeu2, i2, j2, k2
-! ------------------------------------------------------------------------------
     !
     ! -- Set vector components based on ihc
     if (ihc == 0) then
@@ -1215,33 +1066,25 @@ subroutine connection_normal(this, noden, nodem, ihc, xcomp, ycomp, zcomp, &
       !
     end if
     !
-    ! -- return
-    return
   end subroutine connection_normal
 
+  !> @brief Get unit vector components between the cell and a given neighbor
+  !!
+  !! Saturation must be provided to compute cell center vertical coordinates.
+  !! Also return the straight-line connection length.
+  !<
   subroutine connection_vector(this, noden, nodem, nozee, satn, satm, ihc, &
                                xcomp, ycomp, zcomp, conlen)
-! ******************************************************************************
-! connection_vector -- calculate the unit vector components from reduced
-!   nodenumber cell (noden) to its neighbor cell (nodem).  The saturation for
-!   for these cells are also required so that the vertical position of the cell
-!   cell centers can be calculated.  ihc is the horizontal flag.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
-    use ConstantsModule, only: DZERO, DONE, DHALF
     use DisvGeom, only: line_unit_vector
-    use InputOutputModule, only: get_ijk
     ! -- dummy
     class(GwfDisType) :: this
-    integer(I4B), intent(in) :: noden
-    integer(I4B), intent(in) :: nodem
+    integer(I4B), intent(in) :: noden !< cell (reduced nn)
+    integer(I4B), intent(in) :: nodem !< neighbor (reduced nn)
     logical, intent(in) :: nozee
     real(DP), intent(in) :: satn
     real(DP), intent(in) :: satm
-    integer(I4B), intent(in) :: ihc
+    integer(I4B), intent(in) :: ihc !< horizontal connection flag
     real(DP), intent(inout) :: xcomp
     real(DP), intent(inout) :: ycomp
     real(DP), intent(inout) :: zcomp
@@ -1252,7 +1095,6 @@ subroutine connection_vector(this, noden, nodem, nozee, satn, satm, ihc, &
     real(DP) :: ds
     integer(I4B) :: i1, i2, j1, j2, k1, k2
     integer(I4B) :: nodeu1, nodeu2, ipos
-! ------------------------------------------------------------------------------
     !
     ! -- Set vector components based on ihc
     if (ihc == 0) then
@@ -1299,30 +1141,72 @@ subroutine connection_vector(this, noden, nodem, nozee, satn, satm, ihc, &
       call line_unit_vector(x1, y1, z1, x2, y2, z2, xcomp, ycomp, zcomp, conlen)
     end if
     !
-    ! -- return
-    return
   end subroutine
 
-  ! return discretization type
+  !> @brief Get the discretization type
+  !<
   subroutine get_dis_type(this, dis_type)
+    ! -- dummy
     class(GwfDisType), intent(in) :: this
     character(len=*), intent(out) :: dis_type
-
+    !
     dis_type = "DIS"
-
+    !
   end subroutine get_dis_type
 
+  !> @brief Get a 2D array of polygon vertices, listed in
+  !!
+  !! clockwise order beginning with the lower left corner
+  !<
+  subroutine get_polyverts(this, ic, polyverts, closed)
+    ! -- dummy
+    class(GwfDisType), intent(inout) :: this
+    integer(I4B), intent(in) :: ic !< cell number (reduced)
+    real(DP), allocatable, intent(out) :: polyverts(:, :) !< polygon vertices (column-major indexing)
+    logical(LGP), intent(in), optional :: closed !< whether to close the polygon, duplicating a vertex
+    ! -- local
+    integer(I4B) :: icu, nverts, irow, jcol, klay
+    real(DP) :: cellx, celly, dxhalf, dyhalf
+    logical(LGP) :: lclosed
+    !
+    nverts = 4
+    !
+    ! check closed option
+    if (.not. (present(closed))) then
+      lclosed = .false.
+    else
+      lclosed = closed
+    end if
+    !
+    ! allocate vertices array
+    if (lclosed) then
+      allocate (polyverts(2, nverts + 1))
+    else
+      allocate (polyverts(2, nverts))
+    end if
+    !
+    ! set vertices
+    icu = this%get_nodeuser(ic)
+    call get_ijk(icu, this%nrow, this%ncol, this%nlay, irow, jcol, klay)
+    cellx = this%cellx(jcol)
+    celly = this%celly(irow)
+    dxhalf = DHALF * this%delr(jcol)
+    dyhalf = DHALF * this%delc(irow)
+    polyverts(:, 1) = (/cellx - dxhalf, celly - dyhalf/) ! SW
+    polyverts(:, 2) = (/cellx - dxhalf, celly + dyhalf/) ! NW
+    polyverts(:, 3) = (/cellx + dxhalf, celly + dyhalf/) ! NE
+    polyverts(:, 4) = (/cellx + dxhalf, celly - dyhalf/) ! SE
+    !
+    ! close if enabled
+    if (lclosed) &
+      polyverts(:, nverts + 1) = polyverts(:, 1)
+    !
+  end subroutine
+
+  !> @brief Read an integer array
+  !<
   subroutine read_int_array(this, line, lloc, istart, istop, iout, in, &
                             iarray, aname)
-! ******************************************************************************
-! read_int_array -- Read a GWF integer array
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use InputOutputModule, only: urword
-    use ConstantsModule, only: LINELENGTH
     ! -- dummy
     class(GwfDisType), intent(inout) :: this
     character(len=*), intent(inout) :: line
@@ -1341,7 +1225,6 @@ subroutine read_int_array(this, line, lloc, istart, istop, iout, in, &
     integer(I4B) :: ncol
     integer(I4B) :: nval
     integer(I4B), dimension(:), pointer, contiguous :: itemp
-! ------------------------------------------------------------------------------
     !
     ! -- Point the temporary pointer array, which is passed to the reading
     !    subroutine.  The temporary array will point to ibuff if it is a
@@ -1377,21 +1260,12 @@ subroutine read_int_array(this, line, lloc, istart, istop, iout, in, &
       call this%fill_grid_array(itemp, iarray)
     end if
     !
-    ! -- return
-    return
   end subroutine read_int_array
 
+  !> @brief Read a double precision array
+  !<
   subroutine read_dbl_array(this, line, lloc, istart, istop, iout, in, &
                             darray, aname)
-! ******************************************************************************
-! read_dbl_array -- Read a GWF double precision array
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use InputOutputModule, only: urword
-    use ConstantsModule, only: LINELENGTH
     ! -- dummy
     class(GwfDisType), intent(inout) :: this
     character(len=*), intent(inout) :: line
@@ -1410,7 +1284,6 @@ subroutine read_dbl_array(this, line, lloc, istart, istop, iout, in, &
     integer(I4B) :: ncol
     integer(I4B) :: nval
     real(DP), dimension(:), pointer, contiguous :: dtemp
-! ------------------------------------------------------------------------------
     !
     ! -- Point the temporary pointer array, which is passed to the reading
     !    subroutine.  The temporary array will point to dbuff if it is a
@@ -1446,22 +1319,15 @@ subroutine read_dbl_array(this, line, lloc, istart, istop, iout, in, &
       call this%fill_grid_array(dtemp, darray)
     end if
     !
-    ! -- return
-    return
   end subroutine read_dbl_array
 
+  !> @brief Read a 2d double array into col icolbnd of darray
+  !!
+  !! For cells that are outside of the active domain,
+  !! do not copy the array value into darray.
+  !<
   subroutine read_layer_array(this, nodelist, darray, ncolbnd, maxbnd, &
                               icolbnd, aname, inunit, iout)
-! ******************************************************************************
-! read_layer_array -- Read a 2d double array into col icolbnd of darray.
-!                     For cells that are outside of the active domain,
-!                     do not copy the array value into darray.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use InputOutputModule, only: get_node
     ! -- dummy
     class(GwfDisType) :: this
     integer(I4B), intent(in) :: maxbnd
@@ -1474,7 +1340,6 @@ subroutine read_layer_array(this, nodelist, darray, ncolbnd, maxbnd, &
     integer(I4B), intent(in) :: iout
     ! -- local
     integer(I4B) :: ir, ic, ncol, nrow, nlay, nval, ipos, nodeu
-! ------------------------------------------------------------------------------
     !
     ! -- set variables
     nlay = this%mshape(1)
@@ -1500,44 +1365,27 @@ subroutine read_layer_array(this, nodelist, darray, ncolbnd, maxbnd, &
       end do
     end do
     !
-    ! -- return
   end subroutine read_layer_array
 
+  !> @brief Record a double precision array.
+  !!
+  !! The array is written to a formatted or unformatted external file
+  !! depending on the arguments.
+  !<
   subroutine record_array(this, darray, iout, iprint, idataun, aname, &
                           cdatafmp, nvaluesp, nwidthp, editdesc, dinact)
-! ******************************************************************************
-! record_array -- Record a double precision array.  The array will be
-!   printed to an external file and/or written to an unformatted external file
-!   depending on the argument specifications.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-!      darray is the double precision array to record
-!      iout is the unit number for ascii output
-!      iprint is a flag indicating whether or not to print the array
-!      idataun is the unit number to which the array will be written in binary
-!        form; if negative then do not write by layers, write entire array
-!      aname is the text descriptor of the array
-!      cdatafmp is the fortran format for writing the array
-!      nvaluesp is the number of values per line for printing
-!      nwidthp is the width of the number for printing
-!      editdesc is the format type (I, G, F, S, E)
-!      dinact is the double precision value to use for cells that are excluded
-!        from the model domain
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfDisType), intent(inout) :: this
-    real(DP), dimension(:), pointer, contiguous, intent(inout) :: darray
-    integer(I4B), intent(in) :: iout
-    integer(I4B), intent(in) :: iprint
-    integer(I4B), intent(in) :: idataun
-    character(len=*), intent(in) :: aname
-    character(len=*), intent(in) :: cdatafmp
-    integer(I4B), intent(in) :: nvaluesp
-    integer(I4B), intent(in) :: nwidthp
-    character(len=*), intent(in) :: editdesc
-    real(DP), intent(in) :: dinact
+    real(DP), dimension(:), pointer, contiguous, intent(inout) :: darray !< double precision array to record
+    integer(I4B), intent(in) :: iout !< ascii output unit number
+    integer(I4B), intent(in) :: iprint !< whether to print the array
+    integer(I4B), intent(in) :: idataun !< binary output unit number, if negative don't write by layers, write entire array
+    character(len=*), intent(in) :: aname !< text descriptor
+    character(len=*), intent(in) :: cdatafmp !< write format
+    integer(I4B), intent(in) :: nvaluesp !< values per line
+    integer(I4B), intent(in) :: nwidthp !< number width
+    character(len=*), intent(in) :: editdesc !< format type (I, G, F, S, E)
+    real(DP), intent(in) :: dinact !< double precision value for cells excluded from model domain
     ! -- local
     integer(I4B) :: k, ifirst
     integer(I4B) :: nlay
@@ -1551,7 +1399,6 @@ subroutine record_array(this, darray, iout, iprint, idataun, aname, &
     character(len=*), parameter :: fmthsv = &
       "(1X,/1X,a,' WILL BE SAVED ON UNIT ',I4, &
        &' AT END OF TIME STEP',I5,', STRESS PERIOD ',I4)"
-! ------------------------------------------------------------------------------
     !
     ! -- set variables
     nlay = this%mshape(1)
@@ -1609,19 +1456,13 @@ subroutine record_array(this, darray, iout, iprint, idataun, aname, &
                   iout, delt, pertim, totim)
     end if
     !
-    ! -- return
-    return
   end subroutine record_array
 
+  !> @brief Record list header for imeth=6
+  !<
   subroutine record_srcdst_list_header(this, text, textmodel, textpackage, &
                                        dstmodel, dstpackage, naux, auxtxt, &
                                        ibdchn, nlist, iout)
-! ******************************************************************************
-! record_srcdst_list_header -- Record list header for imeth=6
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfDisType) :: this
     character(len=16), intent(in) :: text
@@ -1636,7 +1477,6 @@ subroutine record_srcdst_list_header(this, text, textmodel, textpackage, &
     integer(I4B), intent(in) :: iout
     ! -- local
     integer(I4B) :: nlay, nrow, ncol
-! ------------------------------------------------------------------------------
     !
     nlay = this%mshape(1)
     nrow = this%mshape(2)
@@ -1647,35 +1487,20 @@ subroutine record_srcdst_list_header(this, text, textmodel, textpackage, &
                  ibdchn, naux, auxtxt, ncol, nrow, nlay, &
                  nlist, iout, delt, pertim, totim)
     !
-    ! -- return
-    return
   end subroutine record_srcdst_list_header
 
-  subroutine nlarray_to_nodelist(this, nodelist, maxbnd, nbound, aname, &
-                                 inunit, iout)
-! ******************************************************************************
-! nlarray_to_nodelist -- Read an integer array into nodelist. For structured
-!                        model, integer array is layer number; for unstructured
-!                        model, integer array is node number.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use InputOutputModule, only: get_node
-    use ConstantsModule, only: LINELENGTH
+  !> @brief Convert an integer array (layer numbers) to nodelist
+  !<
+  subroutine nlarray_to_nodelist(this, darray, nodelist, maxbnd, nbound, aname)
     ! -- dummy
     class(GwfDisType) :: this
     integer(I4B), intent(in) :: maxbnd
+    integer(I4B), dimension(:), pointer, contiguous :: darray
     integer(I4B), dimension(maxbnd), intent(inout) :: nodelist
     integer(I4B), intent(inout) :: nbound
     character(len=*), intent(in) :: aname
-    integer(I4B), intent(in) :: inunit
-    integer(I4B), intent(in) :: iout
     ! -- local
     integer(I4B) :: il, ir, ic, ncol, nrow, nlay, nval, nodeu, noder, ipos, ierr
-    character(len=LINELENGTH) :: errmsg
-! ------------------------------------------------------------------------------
     !
     ! -- set variables
     nlay = this%mshape(1)
@@ -1685,8 +1510,6 @@ subroutine nlarray_to_nodelist(this, nodelist, maxbnd, nbound, aname, &
     if (this%ndim > 1) then
       !
       nval = ncol * nrow
-      call ReadArray(inunit, this%ibuff, aname, this%ndim, ncol, nrow, nlay, &
-                     nval, iout, 0, 0)
       !
       ! -- Copy array into nodelist
       ipos = 1
@@ -1694,9 +1517,9 @@ subroutine nlarray_to_nodelist(this, nodelist, maxbnd, nbound, aname, &
       do ir = 1, nrow
         do ic = 1, ncol
           nodeu = get_node(1, ir, ic, nlay, nrow, ncol)
-          il = this%ibuff(nodeu)
+          il = darray(nodeu)
           if (il < 1 .or. il > nlay) then
-            write (errmsg, *) 'INVALID LAYER NUMBER: ', il
+            write (errmsg, '(a,1x,i0)') 'Invalid layer number:', il
             call store_error(errmsg, terminate=.TRUE.)
           end if
           nodeu = get_node(il, ir, ic, nlay, nrow, ncol)
@@ -1713,9 +1536,9 @@ subroutine nlarray_to_nodelist(this, nodelist, maxbnd, nbound, aname, &
       ! -- Check for errors
       nbound = ipos - 1
       if (ierr > 0) then
-        write (errmsg, *) 'MAXBOUND DIMENSION IS TOO SMALL.'
-        call store_error(errmsg)
-        write (errmsg, *) 'INCREASE MAXBOUND TO: ', ierr
+        write (errmsg, '(a,1x,i0)') &
+          'MAXBOUND dimension is too small.'// &
+          'INCREASE MAXBOUND TO:', ierr
         call store_error(errmsg, terminate=.TRUE.)
       end if
       !
@@ -1729,10 +1552,10 @@ subroutine nlarray_to_nodelist(this, nodelist, maxbnd, nbound, aname, &
     else
       !
       ! -- For unstructured, read nodelist directly, then check node numbers
-      call ReadArray(inunit, nodelist, aname, this%ndim, maxbnd, iout, 0)
+      nodelist = darray
       do noder = 1, maxbnd
         if (noder < 1 .or. noder > this%nodes) then
-          write (errmsg, *) 'INVALID NODE NUMBER: ', noder
+          write (errmsg, '(a,1x,i0)') 'Invalid node number:', noder
           call store_error(errmsg, terminate=.TRUE.)
         end if
       end do
@@ -1740,7 +1563,6 @@ subroutine nlarray_to_nodelist(this, nodelist, maxbnd, nbound, aname, &
       !
     end if
     !
-    ! -- return
   end subroutine nlarray_to_nodelist
 
 end module GwfDisModule
diff --git a/src/Model/GroundWaterFlow/gwf3dis8idm.f90 b/src/Model/GroundWaterFlow/gwf3dis8idm.f90
index 0c8d8cd90b1..35a4db3f326 100644
--- a/src/Model/GroundWaterFlow/gwf3dis8idm.f90
+++ b/src/Model/GroundWaterFlow/gwf3dis8idm.f90
@@ -1,5 +1,6 @@
 ! ** Do Not Modify! MODFLOW 6 system generated file. **
 module GwfDisInputModule
+  use ConstantsModule, only: LENVARNAME
   use InputDefinitionModule, only: InputParamDefinitionType, &
                                    InputBlockDefinitionType
   private
@@ -40,7 +41,8 @@ module GwfDisInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -56,7 +58,8 @@ module GwfDisInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -72,7 +75,8 @@ module GwfDisInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -88,7 +92,8 @@ module GwfDisInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -104,7 +109,8 @@ module GwfDisInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -120,7 +126,8 @@ module GwfDisInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -136,7 +143,8 @@ module GwfDisInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -152,7 +160,8 @@ module GwfDisInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -168,7 +177,8 @@ module GwfDisInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -184,7 +194,8 @@ module GwfDisInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -200,7 +211,8 @@ module GwfDisInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -216,7 +228,8 @@ module GwfDisInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -232,7 +245,8 @@ module GwfDisInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -268,7 +282,8 @@ module GwfDisInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     ) &
     ]
 
diff --git a/src/Model/GroundWaterFlow/gwf3disu8.f90 b/src/Model/GroundWaterFlow/gwf3disu8.f90
index 003ba6091c8..e5ee2aaac74 100644
--- a/src/Model/GroundWaterFlow/gwf3disu8.f90
+++ b/src/Model/GroundWaterFlow/gwf3disu8.f90
@@ -3,15 +3,20 @@ module GwfDisuModule
   use ArrayReadersModule, only: ReadArray
   use KindModule, only: DP, I4B, LGP
   use ConstantsModule, only: LINELENGTH, LENMEMPATH, LENVARNAME, &
-                             DZERO, DONE
+                             DZERO, DONE, DHALF
   use ConnectionsModule, only: iac_to_ia
-  use InputOutputModule, only: URWORD, ulasav, ulaprufw, ubdsv1, ubdsv06
+  use InputOutputModule, only: URWORD, ulasav, ulaprufw, ubdsv1, ubdsv06, &
+                               getunit, openfile
   use SimModule, only: count_errors, store_error, store_error_unit, &
                        store_error_filename
-  use SimVariablesModule, only: errmsg
+  use SimVariablesModule, only: errmsg, idm_context
   use BaseDisModule, only: DisBaseType
-  use MemoryManagerModule, only: mem_allocate
+  use MemoryManagerModule, only: mem_allocate, mem_deallocate, &
+                                 mem_reallocate, mem_setptr
+  use MemoryManagerExtModule, only: mem_set_value, memorylist_remove
   use TdisModule, only: kstp, kper, pertim, totim, delt
+  use GwfDisuInputModule, only: GwfDisuParamFoundType
+  use DisvGeom, only: line_unit_vector
 
   implicit none
 
@@ -40,7 +45,9 @@ module GwfDisuModule
     integer(I4B), dimension(:), pointer, contiguous :: javert => null() ! cell vertex pointer ja array
     integer(I4B), dimension(:), pointer, contiguous :: idomain => null() ! idomain (nodes)
     logical(LGP) :: readFromFile ! True, when DIS is read from file (almost always)
+
   contains
+
     procedure :: dis_df => disu_df
     procedure :: disu_load
     procedure :: dis_da => disu_da
@@ -78,20 +85,14 @@ module GwfDisuModule
     ! -- Read a node-sized model array (reduced or not)
     procedure :: read_int_array
     procedure :: read_dbl_array
+
   end type GwfDisuType
 
 contains
 
+  !> @brief Create a new unstructured discretization object
+  !<
   subroutine disu_cr(dis, name_model, input_mempath, inunit, iout)
-! ******************************************************************************
-! disu_cr -- Create discretization object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use KindModule, only: LGP
-    use MemoryManagerExtModule, only: mem_set_value
     ! -- dummy
     class(DisBaseType), pointer :: dis
     character(len=*), intent(in) :: name_model
@@ -100,26 +101,19 @@ subroutine disu_cr(dis, name_model, input_mempath, inunit, iout)
     integer(I4B), intent(in) :: iout
     ! -- local
     type(GwfDisuType), pointer :: disnew
-    logical(LGP) :: found_fname
     character(len=*), parameter :: fmtheader = &
       "(1X, /1X, 'DISU -- UNSTRUCTURED GRID DISCRETIZATION PACKAGE,', &
       &' VERSION 2 : 3/27/2014 - INPUT READ FROM MEMPATH: ', A, //)"
-! ------------------------------------------------------------------------------
     !
     ! -- Create a new discretization object
     allocate (disnew)
     dis => disnew
     !
     ! -- Allocate scalars and assign data
-    call dis%allocate_scalars(name_model)
-    dis%input_mempath = input_mempath
+    call dis%allocate_scalars(name_model, input_mempath)
     dis%inunit = inunit
     dis%iout = iout
     !
-    ! -- set name of input file
-    call mem_set_value(dis%input_fname, 'INPUT_FNAME', dis%input_mempath, &
-                       found_fname)
-    !
     ! -- If disu is enabled
     if (inunit > 0) then
       !
@@ -132,21 +126,13 @@ subroutine disu_cr(dis, name_model, input_mempath, inunit, iout)
       call disnew%disu_load()
     end if
     !
-    ! -- Return
-    return
   end subroutine disu_cr
 
+  !> @brief Transfer IDM data into this discretization object
+  !<
   subroutine disu_load(this)
-! ******************************************************************************
-! disu_load -- transfer data into this discretization object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfDisuType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- source input data
     call this%source_options()
@@ -167,38 +153,21 @@ subroutine disu_load(this)
     !    input
     call this%disu_ck()
     !
-    ! -- Return
-    return
   end subroutine disu_load
 
+  !> @brief Define the discretization
+  !<
   subroutine disu_df(this)
-! ******************************************************************************
-! disu_df -- Read discretization information from DISU input file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfDisuType) :: this
-! ------------------------------------------------------------------------------
     !
-    ! -- Finalize the grid by creating the connection object and reducing the
-    !    grid using IDOMAIN, if necessary
     call this%grid_finalize()
     !
-    ! -- Return
-    return
   end subroutine disu_df
 
+  !> @brief Finalize the grid
+  !<
   subroutine grid_finalize(this)
-! ******************************************************************************
-! grid_finalize -- Finalize grid
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_allocate, mem_reallocate
     ! -- dummy
     class(GwfDisuType) :: this
     ! -- locals
@@ -214,7 +183,6 @@ subroutine grid_finalize(this)
       "(/1x, 'The specified IDOMAIN results in a reduced number of cells.',&
       &/1x, 'Number of user nodes: ',I0,&
       &/1X, 'Number of nodes in solution: ', I0, //)"
-! ------------------------------------------------------------------------------
     !
     ! -- count active cells
     this%nodes = 0
@@ -305,18 +273,11 @@ subroutine grid_finalize(this)
     this%nja = this%con%nja
     this%njas = this%con%njas
     !
-    ! -- Return
-    return
   end subroutine grid_finalize
 
+  !> @brief Check discretization info
+  !<
   subroutine disu_ck(this)
-! ******************************************************************************
-! disu_ck -- Check the discretization information
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfDisuType) :: this
     ! -- local
@@ -339,7 +300,6 @@ subroutine disu_ck(this)
       "('Top elevation (', 1pg15.6, ') for cell ', i0, ' is above bottom &
       &elevation (', 1pg15.6, ') for cell ', i0, '. Based on node numbering &
       &rules cell ', i0, ' must be below cell ', i0, '.')"
-! ------------------------------------------------------------------------------
     !
     ! -- Check connectivity
     do n = 1, this%nodesuser
@@ -433,24 +393,13 @@ subroutine disu_ck(this)
       end if
     end if
     !
-    ! -- Return
-    return
   end subroutine disu_ck
 
+  !> @brief Deallocate variables
+  !<
   subroutine disu_da(this)
-! ******************************************************************************
-! disu_da -- Deallocate discretization object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_deallocate
-    use MemoryManagerExtModule, only: memorylist_remove
-    use SimVariablesModule, only: idm_context
     ! -- dummy
     class(GwfDisuType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Deallocate idm memory
     call memorylist_remove(this%name_model, 'DISU', idm_context)
@@ -480,59 +429,41 @@ subroutine disu_da(this)
       call mem_deallocate(this%hwvainp)
       call mem_deallocate(this%angldegxinp)
     end if
-
+    !
     call mem_deallocate(this%idomain)
     call mem_deallocate(this%cellxy)
-
+    !
     call mem_deallocate(this%nodeuser)
     call mem_deallocate(this%nodereduced)
     !
     ! -- DisBaseType deallocate
     call this%DisBaseType%dis_da()
     !
-    ! -- Return
-    return
   end subroutine disu_da
 
+  !> @brief Convert a user nodenumber to a string (nodenumber)
+  !<
   subroutine nodeu_to_string(this, nodeu, str)
-! ******************************************************************************
-! nodeu_to_string -- Convert user node number to a string in the form of
-! (nodenumber) or (k,i,j)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfDisuType) :: this
     integer(I4B), intent(in) :: nodeu
     character(len=*), intent(inout) :: str
     ! -- local
     character(len=10) :: nstr
-! ------------------------------------------------------------------------------
     !
     write (nstr, '(i0)') nodeu
     str = '('//trim(adjustl(nstr))//')'
     !
-    ! -- return
-    return
   end subroutine nodeu_to_string
 
+  !> @brief Convert a user nodenumber to an array (nodenumber)
+  !<
   subroutine nodeu_to_array(this, nodeu, arr)
-! ******************************************************************************
-! nodeu_to_array -- Convert user node number to cellid and fill array with
-!                   (nodenumber) or (k,j) or (k,i,j)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use InputOutputModule, only: get_ijk
-    implicit none
     class(GwfDisuType) :: this
     integer(I4B), intent(in) :: nodeu
     integer(I4B), dimension(:), intent(inout) :: arr
     ! -- local
     integer(I4B) :: isize
-! ------------------------------------------------------------------------------
     !
     ! -- check the size of arr
     isize = size(arr)
@@ -546,69 +477,57 @@ subroutine nodeu_to_array(this, nodeu, arr)
     ! -- fill array
     arr(1) = nodeu
     !
-    ! -- return
-    return
   end subroutine nodeu_to_array
 
   !> @brief Write user options to list file
   !<
   subroutine log_options(this, found)
-    use GwfDisuInputModule, only: GwfDisuParamFoundType
+    ! -- dummy
     class(GwfDisuType) :: this
     type(GwfDisuParamFoundType), intent(in) :: found
-
+    !
     write (this%iout, '(1x,a)') 'Setting Discretization Options'
-
+    !
     if (found%length_units) then
       write (this%iout, '(4x,a,i0)') 'Model length unit [0=UND, 1=FEET, &
       &2=METERS, 3=CENTIMETERS] set as ', this%lenuni
     end if
-
+    !
     if (found%nogrb) then
       write (this%iout, '(4x,a,i0)') 'Binary grid file [0=GRB, 1=NOGRB] &
         &set as ', this%nogrb
     end if
-
+    !
     if (found%xorigin) then
       write (this%iout, '(4x,a,G0)') 'XORIGIN = ', this%xorigin
     end if
-
+    !
     if (found%yorigin) then
       write (this%iout, '(4x,a,G0)') 'YORIGIN = ', this%yorigin
     end if
-
+    !
     if (found%angrot) then
       write (this%iout, '(4x,a,G0)') 'ANGROT = ', this%angrot
     end if
-
+    !
     if (found%voffsettol) then
       write (this%iout, '(4x,a,G0)') 'VERTICAL_OFFSET_TOLERANCE = ', &
         this%voffsettol
     end if
-
+    !
     write (this%iout, '(1x,a,/)') 'End Setting Discretization Options'
-
+    !
   end subroutine log_options
 
   !> @brief Copy options from IDM into package
   !<
   subroutine source_options(this)
-! ******************************************************************************
-! source_options -- source options from memory manager input path
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerExtModule, only: mem_set_value
-    use GwfDisuInputModule, only: GwfDisuParamFoundType
     ! -- dummy
     class(GwfDisuType) :: this
     ! -- locals
     character(len=LENVARNAME), dimension(3) :: lenunits = &
       &[character(len=LENVARNAME) :: 'FEET', 'METERS', 'CENTIMETERS']
     type(GwfDisuParamFoundType) :: found
-! ------------------------------------------------------------------------------
     !
     ! -- update defaults with idm sourced values
     call mem_set_value(this%lenuni, 'LENGTH_UNITS', this%input_mempath, &
@@ -625,52 +544,40 @@ subroutine source_options(this)
       call this%log_options(found)
     end if
     !
-    ! -- Return
-    return
   end subroutine source_options
 
   !> @brief Write dimensions to list file
   !<
   subroutine log_dimensions(this, found)
-    use GwfDisuInputModule, only: GwfDisuParamFoundType
     class(GwfDisuType) :: this
     type(GwfDisuParamFoundType), intent(in) :: found
-
+    !
     write (this%iout, '(1x,a)') 'Setting Discretization Dimensions'
-
+    !
     if (found%nodes) then
       write (this%iout, '(4x,a,i0)') 'NODES = ', this%nodesuser
     end if
-
+    !
     if (found%nja) then
       write (this%iout, '(4x,a,i0)') 'NJA = ', this%njausr
     end if
-
+    !
     if (found%nvert) then
       write (this%iout, '(4x,a,i0)') 'NVERT = ', this%nvert
     end if
-
+    !
     write (this%iout, '(1x,a,/)') 'End Setting Discretization Dimensions'
-
+    !
   end subroutine log_dimensions
 
   !> @brief Copy dimensions from IDM into package
   !<
   subroutine source_dimensions(this)
-! ******************************************************************************
-! source_dimensions -- source dimensions from memory manager input path
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use MemoryManagerExtModule, only: mem_set_value
-    use GwfDisuInputModule, only: GwfDisuParamFoundType
     ! -- dummy
     class(GwfDisuType) :: this
     ! -- locals
     integer(I4B) :: n
     type(GwfDisuParamFoundType) :: found
-! ------------------------------------------------------------------------------
     !
     ! -- update defaults with idm sourced values
     call mem_set_value(this%nodesuser, 'NODES', this%input_mempath, found%nodes)
@@ -722,55 +629,44 @@ subroutine source_dimensions(this)
       this%idomain(n) = 1
     end do
     !
-    ! -- Return
-    return
   end subroutine source_dimensions
 
   !> @brief Write griddata found to list file
   !<
   subroutine log_griddata(this, found)
-    use GwfDisuInputModule, only: GwfDisuParamFoundType
+    ! -- dummy
     class(GwfDisuType) :: this
     type(GwfDisuParamFoundType), intent(in) :: found
-
+    !
     write (this%iout, '(1x,a)') 'Setting Discretization Griddata'
-
+    !
     if (found%top) then
       write (this%iout, '(4x,a)') 'TOP set from input file'
     end if
-
+    !
     if (found%bot) then
       write (this%iout, '(4x,a)') 'BOT set from input file'
     end if
-
+    !
     if (found%area) then
       write (this%iout, '(4x,a)') 'AREA set from input file'
     end if
-
+    !
     if (found%idomain) then
       write (this%iout, '(4x,a)') 'IDOMAIN set from input file'
     end if
-
+    !
     write (this%iout, '(1x,a,/)') 'End Setting Discretization Griddata'
-
+    !
   end subroutine log_griddata
 
+  !> @brief Copy grid data from IDM into package
+  !<
   subroutine source_griddata(this)
-! ******************************************************************************
-! source_griddata -- source griddata from memory manager input path
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerExtModule, only: mem_set_value
-    use GwfDisuInputModule, only: GwfDisuParamFoundType
     ! -- dummy
     class(GwfDisuType) :: this
     ! -- locals
     type(GwfDisuParamFoundType) :: found
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- update defaults with idm sourced values
     call mem_set_value(this%top1d, 'TOP', this%input_mempath, found%top)
@@ -783,66 +679,54 @@ subroutine source_griddata(this)
       call this%log_griddata(found)
     end if
     !
-    ! -- Return
-    return
   end subroutine source_griddata
 
   !> @brief Write griddata found to list file
   !<
   subroutine log_connectivity(this, found, iac)
-    use GwfDisuInputModule, only: GwfDisuParamFoundType
     class(GwfDisuType) :: this
     type(GwfDisuParamFoundType), intent(in) :: found
     integer(I4B), dimension(:), contiguous, pointer, intent(in) :: iac
-
+    !
     write (this%iout, '(1x,a)') 'Setting Discretization Connectivity'
-
+    !
     if (associated(iac)) then
       write (this%iout, '(4x,a)') 'IAC set from input file'
     end if
-
+    !
     if (found%ja) then
       write (this%iout, '(4x,a)') 'JA set from input file'
     end if
-
+    !
     if (found%ihc) then
       write (this%iout, '(4x,a)') 'IHC set from input file'
     end if
-
+    !
     if (found%cl12) then
       write (this%iout, '(4x,a)') 'CL12 set from input file'
     end if
-
+    !
     if (found%hwva) then
       write (this%iout, '(4x,a)') 'HWVA set from input file'
     end if
-
+    !
     if (found%angldegx) then
       write (this%iout, '(4x,a)') 'ANGLDEGX set from input file'
     end if
-
+    !
     write (this%iout, '(1x,a,/)') 'End Setting Discretization Connectivity'
-
+    !
   end subroutine log_connectivity
 
+  !> @brief Copy grid connectivity info from IDM into package
+  !<
   subroutine source_connectivity(this)
-! ******************************************************************************
-! source_connectivity -- source connection data from memory manager input path
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_setptr
-    use MemoryManagerExtModule, only: mem_set_value
-    use GwfDisuInputModule, only: GwfDisuParamFoundType
     ! -- dummy
     class(GwfDisuType) :: this
     ! -- locals
     type(GwfDisuParamFoundType) :: found
     integer(I4B), dimension(:), contiguous, pointer :: iac => null()
     ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- update defaults with idm sourced values
     call mem_set_value(this%jainp, 'JA', this%input_mempath, found%ja)
@@ -866,19 +750,11 @@ subroutine source_connectivity(this)
       call this%log_connectivity(found, iac)
     end if
     !
-    ! -- Return
-    return
   end subroutine source_connectivity
 
+  !> @brief Copy grid vertex data from IDM into package
+  !<
   subroutine source_vertices(this)
-! ******************************************************************************
-! source_vertices -- source vertex data from memory manager input path
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_setptr
     ! -- dummy
     class(GwfDisuType) :: this
     ! -- local
@@ -886,7 +762,6 @@ subroutine source_vertices(this)
     real(DP), dimension(:), contiguous, pointer :: vert_x => null()
     real(DP), dimension(:), contiguous, pointer :: vert_y => null()
     ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- set pointers to memory manager input arrays
     call mem_setptr(vert_x, 'XV', this%input_mempath)
@@ -907,10 +782,10 @@ subroutine source_vertices(this)
       write (this%iout, '(1x,a)') 'Discretization Vertex data loaded'
     end if
     !
-    ! -- Return
-    return
   end subroutine source_vertices
 
+  !> @brief Build data structures to hold cell vertex info
+  !<
   subroutine define_cellverts(this, icell2d, ncvert, icvert)
     ! -- modules
     use SparseModule, only: sparsematrix
@@ -923,7 +798,6 @@ subroutine define_cellverts(this, icell2d, ncvert, icvert)
     type(sparsematrix) :: vert_spm
     integer(I4B) :: i, j, ierr
     integer(I4B) :: icv_idx, startvert, maxnnz = 5
-! ------------------------------------------------------------------------------
     !
     ! -- initialize sparse matrix
     call vert_spm%init(this%nodesuser, this%nvert, maxnnz)
@@ -949,19 +823,11 @@ subroutine define_cellverts(this, icell2d, ncvert, icvert)
     call vert_spm%filliaja(this%iavert, this%javert, ierr)
     call vert_spm%destroy()
     !
-    ! -- Return
-    return
   end subroutine define_cellverts
 
+  !> @brief Copy cell2d data from IDM into package
+  !<
   subroutine source_cell2d(this)
-! ******************************************************************************
-! source_cell2d -- source cell2d data from memory manager input path
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_setptr
     ! -- dummy
     class(GwfDisuType) :: this
     ! -- locals
@@ -971,8 +837,6 @@ subroutine source_cell2d(this)
     real(DP), dimension(:), contiguous, pointer :: cell_x => null()
     real(DP), dimension(:), contiguous, pointer :: cell_y => null()
     integer(I4B) :: i
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- set pointers to input path ncvert and icvert
     call mem_setptr(icell2d, 'ICELL2D', this%input_mempath)
@@ -1006,19 +870,12 @@ subroutine source_cell2d(this)
       write (this%iout, '(1x,a)') 'Discretization Cell2d data loaded'
     end if
     !
-    ! -- Return
-    return
   end subroutine source_cell2d
 
+  !> @brief Write a binary grid file
+  !<
   subroutine write_grb(this, icelltype)
-! ******************************************************************************
-! write_grb -- Write the binary grid file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
-    use InputOutputModule, only: getunit, openfile
     use OpenSpecModule, only: access, form
     ! -- dummy
     class(GwfDisuType) :: this
@@ -1029,10 +886,10 @@ subroutine write_grb(this, icelltype)
     character(len=50) :: txthdr
     character(len=lentxt) :: txt
     character(len=LINELENGTH) :: fname
+    ! -- formats
     character(len=*), parameter :: fmtgrdsave = &
       "(4X,'BINARY GRID INFORMATION WILL BE WRITTEN TO:', &
        &/,6X,'UNIT NUMBER: ', I0,/,6X, 'FILE NAME: ', A)"
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize
     ntxt = 10
@@ -1134,30 +991,21 @@ subroutine write_grb(this, icelltype)
     ! -- Close the file
     close (iunit)
     !
-    ! -- return
-    return
   end subroutine write_grb
 
+  !> @brief Get reduced node number from user node number
+  !<
   function get_nodenumber_idx1(this, nodeu, icheck) result(nodenumber)
-! ******************************************************************************
-! get_nodenumber -- Return a nodenumber from the user specified node number
-!                   with an option to perform a check.  This subroutine
-!                   can be overridden by child classes to perform mapping
-!                   to a model node number
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     class(GwfDisuType), intent(in) :: this
     integer(I4B), intent(in) :: nodeu
     integer(I4B), intent(in) :: icheck
     integer(I4B) :: nodenumber
-! ------------------------------------------------------------------------------
     !
     if (icheck /= 0) then
       if (nodeu < 1 .or. nodeu > this%nodes) then
-        write (errmsg, '(a,i10)') &
-          'Nodenumber less than 1 or greater than nodes:', nodeu
+        write (errmsg, '(a,i0,a,i0,a)') &
+          'Node number (', nodeu, ') is less than 1 or greater than nodes (', &
+          this%nodes, ').'
         call store_error(errmsg)
       end if
     end if
@@ -1170,33 +1018,25 @@ function get_nodenumber_idx1(this, nodeu, icheck) result(nodenumber)
       nodenumber = this%nodereduced(nodeu)
     end if
     !
-    ! -- return
-    return
   end function get_nodenumber_idx1
 
+  !> @brief Get normal vector components between the cell and a given neighbor
+  !!
+  !! The normal points outward from the shared face between noden and nodem.
+  !<
   subroutine connection_normal(this, noden, nodem, ihc, xcomp, ycomp, zcomp, &
                                ipos)
-! ******************************************************************************
-! connection_normal -- calculate the normal vector components for reduced
-!   nodenumber cell (noden) and its shared face with cell nodem.  ihc is the
-!   horizontal connection flag.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfDisuType) :: this
-    integer(I4B), intent(in) :: noden
-    integer(I4B), intent(in) :: nodem
-    integer(I4B), intent(in) :: ihc
+    integer(I4B), intent(in) :: noden !< cell (reduced nn)
+    integer(I4B), intent(in) :: nodem !< neighbor (reduced nn)
+    integer(I4B), intent(in) :: ihc !< horizontal connection flag
     real(DP), intent(inout) :: xcomp
     real(DP), intent(inout) :: ycomp
     real(DP), intent(inout) :: zcomp
     integer(I4B), intent(in) :: ipos
     ! -- local
     real(DP) :: angle, dmult
-! ------------------------------------------------------------------------------
     !
     ! -- Set vector components based on ihc
     if (ihc == 0) then
@@ -1224,25 +1064,15 @@ subroutine connection_normal(this, noden, nodem, ihc, xcomp, ycomp, zcomp, &
       zcomp = DZERO
     end if
     !
-    ! -- return
-    return
   end subroutine connection_normal
 
+  !> @brief Get unit vector components between the cell and a given neighbor
+  !!
+  !! Saturation must be provided to compute cell center vertical coordinates.
+  !! Also return the straight-line connection length.
+  !<
   subroutine connection_vector(this, noden, nodem, nozee, satn, satm, ihc, &
                                xcomp, ycomp, zcomp, conlen)
-! ******************************************************************************
-! connection_vector -- calculate the unit vector components from reduced
-!   nodenumber cell (noden) to its neighbor cell (nodem).  The saturation for
-!   for these cells are also required so that the vertical position of the cell
-!   cell centers can be calculated.  ihc is the horizontal flag.  Also return
-!   the straight-line connection length.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use ConstantsModule, only: DHALF
-    use DisvGeom, only: line_unit_vector
     ! -- dummy
     class(GwfDisuType) :: this
     integer(I4B), intent(in) :: noden
@@ -1257,7 +1087,6 @@ subroutine connection_vector(this, noden, nodem, nozee, satn, satm, ihc, &
     real(DP), intent(inout) :: conlen
     ! -- local
     real(DP) :: xn, xm, yn, ym, zn, zm
-! ------------------------------------------------------------------------------
     !
     ! -- Terminate with error if requesting unit vector components for problems
     !    without cell data
@@ -1297,36 +1126,29 @@ subroutine connection_vector(this, noden, nodem, nozee, satn, satm, ihc, &
     call line_unit_vector(xn, yn, zn, xm, ym, zm, xcomp, ycomp, zcomp, &
                           conlen)
     !
-    ! -- return
-    return
   end subroutine connection_vector
 
-  ! return discretization type
+  !> @brief Get the discretization type
+  !<
   subroutine get_dis_type(this, dis_type)
+    ! -- dummy
     class(GwfDisuType), intent(in) :: this
     character(len=*), intent(out) :: dis_type
-
+    !
     dis_type = "DISU"
-
+    !
   end subroutine get_dis_type
 
-  subroutine allocate_scalars(this, name_model)
-! ******************************************************************************
-! allocate_scalars -- Allocate and initialize scalar variables in this class
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_allocate
+  !> @brief Allocate and initialize scalar variables
+  !<
+  subroutine allocate_scalars(this, name_model, input_mempath)
     ! -- dummy
     class(GwfDisuType) :: this
     character(len=*), intent(in) :: name_model
-    ! -- local
-! ------------------------------------------------------------------------------
+    character(len=*), intent(in) :: input_mempath
     !
     ! -- Allocate parent scalars
-    call this%DisBaseType%allocate_scalars(name_model)
+    call this%DisBaseType%allocate_scalars(name_model, input_mempath)
     !
     ! -- Allocate variables for DISU
     call mem_allocate(this%njausr, 'NJAUSR', this%memoryPath)
@@ -1342,23 +1164,13 @@ subroutine allocate_scalars(this, name_model)
     this%iangledegx = 0
     this%readFromFile = .false.
     !
-    ! -- Return
-    return
   end subroutine allocate_scalars
 
+  !> @brief Allocate and initialize arrays
+  !<
   subroutine allocate_arrays(this)
-! ******************************************************************************
-! allocate_arrays -- Read discretization information from file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwfDisuType) :: this
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate arrays in DisBaseType (mshape, top, bot, area)
     call this%DisBaseType%allocate_arrays()
@@ -1376,32 +1188,30 @@ subroutine allocate_arrays(this)
     ! -- Initialize
     this%mshape(1) = this%nodesuser
     !
-    ! -- Return
-    return
   end subroutine allocate_arrays
 
+  !> @brief Allocate arrays in memory manager
+  !<
   subroutine allocate_arrays_mem(this)
+    ! -- modules
     use MemoryManagerModule, only: mem_allocate
+    ! -- dummy
     class(GwfDisuType) :: this
-
+    !
     call mem_allocate(this%idomain, this%nodes, 'IDOMAIN', this%memoryPath)
     call mem_allocate(this%vertices, 2, this%nvert, 'VERTICES', this%memoryPath)
     call mem_allocate(this%cellxy, 2, this%nodes, 'CELLXY', this%memoryPath)
-
+    !
   end subroutine allocate_arrays_mem
 
+  !> @brief Convert a string to a user nodenumber
+  !!
+  !! Parse and return user nodenumber.
+  !! If flag_string is present and true, the first token may be
+  !! non-numeric (e.g. boundary name). In this case, return -2.
+  !<
   function nodeu_from_string(this, lloc, istart, istop, in, iout, line, &
                              flag_string, allow_zero) result(nodeu)
-! ******************************************************************************
-! nodeu_from_string -- Receive a string and convert the string to a user
-!   nodenumber.  The model is unstructured; just read user nodenumber.
-!   If flag_string argument is present and true, the first token in string
-!   is allowed to be a string (e.g. boundary name). In this case, if a string
-!   is encountered, return value as -2.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfDisuType) :: this
     integer(I4B), intent(inout) :: lloc
@@ -1416,8 +1226,6 @@ function nodeu_from_string(this, lloc, istart, istop, in, iout, line, &
     ! -- local
     integer(I4B) :: lloclocal, ndum, istat, n
     real(DP) :: r
-    character(len=LINELENGTH) :: fname
-! ------------------------------------------------------------------------------
     !
     if (present(flag_string)) then
       if (flag_string) then
@@ -1444,36 +1252,26 @@ function nodeu_from_string(this, lloc, istart, istop, in, iout, line, &
     end if
     !
     if (nodeu < 1 .or. nodeu > this%nodesuser) then
-      write (errmsg, *) ' Node number in list is outside of the grid', nodeu
+      write (errmsg, '(a,i0,a)') &
+        "Node number in list (", nodeu, ") is outside of the grid. "// &
+        "Cell number cannot be determined in line '"// &
+        trim(adjustl(line))//"'."
       call store_error(errmsg)
-      inquire (unit=in, name=fname)
-      call store_error('Error converting in file: ')
-      call store_error(trim(adjustl(fname)))
-      call store_error('Cell number cannot be determined in line: ')
-      call store_error(trim(adjustl(line)))
       call store_error_unit(in)
     end if
     !
-    ! -- return
-    return
-
   end function nodeu_from_string
 
+  !> @brief Convert a cellid string to a user nodenumber
+  !!
+  !! If flag_string is present and true, the first token may be
+  !! non-numeric (e.g. boundary name). In this case, return -2.
+  !!
+  !! If allow_zero is present and true, and all indices are zero, the
+  !! result can be zero. If allow_zero is false, a zero in any index is an error.
+  !<
   function nodeu_from_cellid(this, cellid, inunit, iout, flag_string, &
                              allow_zero) result(nodeu)
-! ******************************************************************************
-! nodeu_from_cellid -- Receive cellid as a string and convert the string to a
-!   user nodenumber.
-!   If flag_string argument is present and true, the first token in string
-!   is allowed to be a string (e.g. boundary name). In this case, if a string
-!   is encountered, return value as -2.
-!   If allow_zero argument is present and true, if all indices equal zero, the
-!   result can be zero. If allow_zero is false, a zero in any index causes an
-!   error.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     integer(I4B) :: nodeu
     ! -- dummy
@@ -1487,8 +1285,6 @@ function nodeu_from_cellid(this, cellid, inunit, iout, flag_string, &
     integer(I4B) :: lloclocal, istart, istop, ndum, n
     integer(I4B) :: istat
     real(DP) :: r
-    character(len=LINELENGTH) :: fname
-! ------------------------------------------------------------------------------
     !
     if (present(flag_string)) then
       if (flag_string) then
@@ -1516,59 +1312,42 @@ function nodeu_from_cellid(this, cellid, inunit, iout, flag_string, &
     end if
     !
     if (nodeu < 1 .or. nodeu > this%nodesuser) then
-      write (errmsg, *) ' Node number in list is outside of the grid', nodeu
+      write (errmsg, '(a,i0,a)') &
+        "Cell number cannot be determined for cellid ("// &
+        trim(adjustl(cellid))//") and results in a user "// &
+        "node number (", nodeu, ") that is outside of the grid."
       call store_error(errmsg)
-      inquire (unit=inunit, name=fname)
-      call store_error('Error converting in file: ')
-      call store_error(trim(adjustl(fname)))
-      call store_error('Cell number cannot be determined in cellid: ')
-      call store_error(trim(adjustl(cellid)))
       call store_error_unit(inunit)
     end if
     !
-    ! -- return
-    return
   end function nodeu_from_cellid
 
+  !> @brief Indicates whether the grid discretization supports layers
+  !<
   logical function supports_layers(this)
-    implicit none
     ! -- dummy
     class(GwfDisuType) :: this
     !
     supports_layers = .false.
-    return
+    !
   end function supports_layers
 
+  !> @brief Get number of cells per layer (total nodes since DISU isn't layered)
+  !<
   function get_ncpl(this)
-! ******************************************************************************
-! get_ncpl -- Return number of cells per layer.  This is nodes
-!   for a DISU grid, as there are no layers.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- return
     integer(I4B) :: get_ncpl
     ! -- dummy
     class(GwfDisuType) :: this
-! ------------------------------------------------------------------------------
     !
     get_ncpl = this%nodesuser
     !
-    ! -- Return
-    return
   end function get_ncpl
 
+  !> @brief Read an integer array
+  !<
   subroutine read_int_array(this, line, lloc, istart, istop, iout, in, &
                             iarray, aname)
-! ******************************************************************************
-! read_int_array -- Read a GWF integer array
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfDisuType), intent(inout) :: this
     character(len=*), intent(inout) :: line
@@ -1582,7 +1361,6 @@ subroutine read_int_array(this, line, lloc, istart, istop, iout, in, &
     ! -- local
     integer(I4B) :: nval
     integer(I4B), dimension(:), pointer, contiguous :: itemp
-! ------------------------------------------------------------------------------
     !
     ! -- Point the temporary pointer array, which is passed to the reading
     !    subroutine.  The temporary array will point to ibuff if it is a
@@ -1605,19 +1383,12 @@ subroutine read_int_array(this, line, lloc, istart, istop, iout, in, &
       call this%fill_grid_array(itemp, iarray)
     end if
     !
-    ! -- return
-    return
   end subroutine read_int_array
 
+  !> @brief Read a double precision array
+  !<
   subroutine read_dbl_array(this, line, lloc, istart, istop, iout, in, &
                             darray, aname)
-! ******************************************************************************
-! read_dbl_array -- Read a GWF double precision array
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfDisuType), intent(inout) :: this
     character(len=*), intent(inout) :: line
@@ -1631,7 +1402,6 @@ subroutine read_dbl_array(this, line, lloc, istart, istop, iout, in, &
     ! -- local
     integer(I4B) :: nval
     real(DP), dimension(:), pointer, contiguous :: dtemp
-! ------------------------------------------------------------------------------
     !
     ! -- Point the temporary pointer array, which is passed to the reading
     !    subroutine.  The temporary array will point to dbuff if it is a
@@ -1653,45 +1423,27 @@ subroutine read_dbl_array(this, line, lloc, istart, istop, iout, in, &
       call this%fill_grid_array(dtemp, darray)
     end if
     !
-    ! -- return
-    return
   end subroutine read_dbl_array
 
+  !> @brief Record a double precision array
+  !!
+  !! The array is written to a formatted or unformatted external file
+  !! depending on the arguments.
+  !<
   subroutine record_array(this, darray, iout, iprint, idataun, aname, &
                           cdatafmp, nvaluesp, nwidthp, editdesc, dinact)
-! ******************************************************************************
-! record_array -- Record a double precision array.  The array will be
-!   printed to an external file and/or written to an unformatted external file
-!   depending on the argument specifications.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-!      darray is the double precision array to record
-!      iout is the unit number for ascii output
-!      iprint is a flag indicating whether or not to print the array
-!      idataun is the unit number to which the array will be written in binary
-!        form; if negative then do not write by layers, write entire array
-!      aname is the text descriptor of the array
-!      cdatafmp is the fortran format for writing the array
-!      nvaluesp is the number of values per line for printing
-!      nwidthp is the width of the number for printing
-!      editdesc is the format type (I, G, F, S, E)
-!      dinact is the double precision value to use for cells that are excluded
-!        from the model domain
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfDisuType), intent(inout) :: this
-    real(DP), dimension(:), pointer, contiguous, intent(inout) :: darray
-    integer(I4B), intent(in) :: iout
-    integer(I4B), intent(in) :: iprint
-    integer(I4B), intent(in) :: idataun
-    character(len=*), intent(in) :: aname
-    character(len=*), intent(in) :: cdatafmp
-    integer(I4B), intent(in) :: nvaluesp
-    integer(I4B), intent(in) :: nwidthp
-    character(len=*), intent(in) :: editdesc
-    real(DP), intent(in) :: dinact
+    real(DP), dimension(:), pointer, contiguous, intent(inout) :: darray !< double precision array to record
+    integer(I4B), intent(in) :: iout !< ascii output unit number
+    integer(I4B), intent(in) :: iprint !< whether to print the array
+    integer(I4B), intent(in) :: idataun !< binary output unit number
+    character(len=*), intent(in) :: aname !< text descriptor
+    character(len=*), intent(in) :: cdatafmp ! write format
+    integer(I4B), intent(in) :: nvaluesp !< values per line
+    integer(I4B), intent(in) :: nwidthp !< number width
+    character(len=*), intent(in) :: editdesc !< format type (I, G, F, S, E)
+    real(DP), intent(in) :: dinact !< double precision value for cells excluded from model domain
     ! -- local
     integer(I4B) :: k, ifirst
     integer(I4B) :: nlay
@@ -1705,7 +1457,6 @@ subroutine record_array(this, darray, iout, iprint, idataun, aname, &
     character(len=*), parameter :: fmthsv = &
       "(1X,/1X,a,' WILL BE SAVED ON UNIT ',I4, &
        &' AT END OF TIME STEP',I5,', STRESS PERIOD ',I4)"
-! ------------------------------------------------------------------------------
     !
     ! -- set variables
     nlay = 1
@@ -1763,19 +1514,13 @@ subroutine record_array(this, darray, iout, iprint, idataun, aname, &
                   iout, delt, pertim, totim)
     end if
     !
-    ! -- return
-    return
   end subroutine record_array
 
+  !> @brief Record list header for imeth=6
+  !<
   subroutine record_srcdst_list_header(this, text, textmodel, textpackage, &
                                        dstmodel, dstpackage, naux, auxtxt, &
                                        ibdchn, nlist, iout)
-! ******************************************************************************
-! record_srcdst_list_header -- Record list header for imeth=6
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfDisuType) :: this
     character(len=16), intent(in) :: text
@@ -1790,7 +1535,6 @@ subroutine record_srcdst_list_header(this, text, textmodel, textpackage, &
     integer(I4B), intent(in) :: iout
     ! -- local
     integer(I4B) :: nlay, nrow, ncol
-! ------------------------------------------------------------------------------
     !
     nlay = 1
     nrow = 1
@@ -1801,22 +1545,22 @@ subroutine record_srcdst_list_header(this, text, textmodel, textpackage, &
                  ibdchn, naux, auxtxt, ncol, nrow, nlay, &
                  nlist, iout, delt, pertim, totim)
     !
-    ! -- return
-    return
   end subroutine record_srcdst_list_header
 
   !> @brief Cast base to DISU
   !<
   function CastAsDisuType(dis) result(disu)
+    ! -- dummy
     class(*), pointer :: dis !< base pointer to DISU object
+    ! -- return
     class(GwfDisuType), pointer :: disu !< the resulting DISU pointer
-
+    !
     disu => null()
     select type (dis)
     class is (GwfDisuType)
       disu => dis
     end select
-
+    !
   end function CastAsDisuType
 
 end module GwfDisuModule
diff --git a/src/Model/GroundWaterFlow/gwf3disu8idm.f90 b/src/Model/GroundWaterFlow/gwf3disu8idm.f90
index 10a61f84702..7f09d38be19 100644
--- a/src/Model/GroundWaterFlow/gwf3disu8idm.f90
+++ b/src/Model/GroundWaterFlow/gwf3disu8idm.f90
@@ -1,5 +1,6 @@
 ! ** Do Not Modify! MODFLOW 6 system generated file. **
 module GwfDisuInputModule
+  use ConstantsModule, only: LENVARNAME
   use InputDefinitionModule, only: InputParamDefinitionType, &
                                    InputBlockDefinitionType
   private
@@ -54,7 +55,8 @@ module GwfDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -70,7 +72,8 @@ module GwfDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -86,7 +89,8 @@ module GwfDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -102,7 +106,8 @@ module GwfDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -118,7 +123,8 @@ module GwfDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -134,7 +140,8 @@ module GwfDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -150,7 +157,8 @@ module GwfDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -166,7 +174,8 @@ module GwfDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -182,7 +191,8 @@ module GwfDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -198,7 +208,8 @@ module GwfDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -214,7 +225,8 @@ module GwfDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -230,7 +242,8 @@ module GwfDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -246,7 +259,8 @@ module GwfDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -262,7 +276,8 @@ module GwfDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -278,7 +293,8 @@ module GwfDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -294,7 +310,8 @@ module GwfDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -310,7 +327,8 @@ module GwfDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -326,7 +344,8 @@ module GwfDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -342,7 +361,8 @@ module GwfDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -358,7 +378,8 @@ module GwfDisuInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -374,7 +395,8 @@ module GwfDisuInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -390,7 +412,8 @@ module GwfDisuInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -406,7 +429,8 @@ module GwfDisuInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -422,7 +446,8 @@ module GwfDisuInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -438,7 +463,8 @@ module GwfDisuInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -454,7 +480,8 @@ module GwfDisuInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -470,7 +497,8 @@ module GwfDisuInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -515,10 +543,11 @@ module GwfDisuInputModule
     'VERTICES', & ! fortran variable
     'RECARRAY IV XV YV', & ! type
     'NVERT', & ! shape
-    .true., & ! required
+    .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -531,10 +560,11 @@ module GwfDisuInputModule
     'CELL2D', & ! fortran variable
     'RECARRAY ICELL2D XC YC NCVERT ICVERT', & ! type
     'NODES', & ! shape
-    .true., & ! required
+    .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -573,13 +603,13 @@ module GwfDisuInputModule
     ), &
     InputBlockDefinitionType( &
     'VERTICES', & ! blockname
-    .true., & ! required
+    .false., & ! required
     .true., & ! aggregate
     .false. & ! block_variable
     ), &
     InputBlockDefinitionType( &
     'CELL2D', & ! blockname
-    .true., & ! required
+    .false., & ! required
     .true., & ! aggregate
     .false. & ! block_variable
     ) &
diff --git a/src/Model/GroundWaterFlow/gwf3disv8.f90 b/src/Model/GroundWaterFlow/gwf3disv8.f90
index 63630cc0190..41237ddacf8 100644
--- a/src/Model/GroundWaterFlow/gwf3disv8.f90
+++ b/src/Model/GroundWaterFlow/gwf3disv8.f90
@@ -1,17 +1,21 @@
 module GwfDisvModule
 
   use ArrayReadersModule, only: ReadArray
-  use KindModule, only: DP, I4B
-  use ConstantsModule, only: LINELENGTH, LENMEMPATH, LENVARNAME, DZERO, DONE, &
-                             DHALF
+  use KindModule, only: DP, I4B, LGP
+  use ConstantsModule, only: LINELENGTH, LENMEMPATH, LENVARNAME, &
+                             DZERO, DONE, DHALF
   use BaseDisModule, only: DisBaseType
-  use InputOutputModule, only: get_node, URWORD, ulasav, ulaprufw, ubdsv1, &
-                               ubdsv06
+  use GeomUtilModule, only: get_node, get_ijk, get_jk
+  use InputOutputModule, only: URWORD, ulasav, &
+                               ulaprufw, ubdsv1, ubdsv06, getunit, openfile
   use SimModule, only: count_errors, store_error, store_error_unit, &
                        store_error_filename
-  use DisvGeom, only: DisvGeomType
-  use MemoryManagerModule, only: mem_allocate
+  use SimVariablesModule, only: errmsg, idm_context
+  use DisvGeom, only: DisvGeomType, line_unit_vector
+  use MemoryManagerModule, only: mem_allocate, mem_deallocate, mem_setptr
+  use MemoryManagerExtModule, only: mem_set_value, memorylist_remove
   use TdisModule, only: kstp, kper, pertim, totim, delt
+  use GwfDisvInputModule, only: GwfDisvParamFoundType
 
   implicit none
   private
@@ -28,7 +32,9 @@ module GwfDisvModule
     real(DP), dimension(:), pointer, contiguous :: top1d => null() ! top elevations for each cell at top of model (ncpl)
     real(DP), dimension(:, :), pointer, contiguous :: bot2d => null() ! bottom elevations for each cell (ncpl, nlay)
     integer(I4B), dimension(:, :), pointer, contiguous :: idomain => null() ! idomain (ncpl, nlay)
+
   contains
+
     procedure :: dis_df => disv_df
     procedure :: dis_da => disv_da
     procedure :: disv_load
@@ -48,6 +54,7 @@ module GwfDisvModule
     procedure :: connection_vector
     procedure :: supports_layers
     procedure :: get_ncpl
+    procedure :: get_polyverts
     ! -- private
     procedure :: source_options
     procedure :: source_dimensions
@@ -65,44 +72,36 @@ module GwfDisvModule
     procedure :: allocate_arrays
     procedure :: get_cell2d_area
     !
+    ! -- Read a node-sized model array (reduced or not)
     procedure :: read_int_array
     procedure :: read_dbl_array
-    !
+
   end type GwfDisvType
 
 contains
 
+  !> @brief Create a new discretization by vertices object
+  !<
   subroutine disv_cr(dis, name_model, input_mempath, inunit, iout)
-! ******************************************************************************
-! disv_cr -- Create a new discretization by vertices object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use KindModule, only: LGP
-    use MemoryManagerExtModule, only: mem_set_value
+    ! -- dummy
     class(DisBaseType), pointer :: dis
     character(len=*), intent(in) :: name_model
     character(len=*), intent(in) :: input_mempath
     integer(I4B), intent(in) :: inunit
     integer(I4B), intent(in) :: iout
+    ! -- local
     type(GwfDisvType), pointer :: disnew
-    logical(LGP) :: found_fname
+    ! -- formats
     character(len=*), parameter :: fmtheader = &
       "(1X, /1X, 'DISV -- VERTEX GRID DISCRETIZATION PACKAGE,', &
       &' VERSION 1 : 12/23/2015 - INPUT READ FROM MEMPATH: ', A, //)"
-! ------------------------------------------------------------------------------
+    !
     allocate (disnew)
     dis => disnew
-    call disnew%allocate_scalars(name_model)
-    dis%input_mempath = input_mempath
+    call disnew%allocate_scalars(name_model, input_mempath)
     dis%inunit = inunit
     dis%iout = iout
     !
-    ! -- set name of input file
-    call mem_set_value(dis%input_fname, 'INPUT_FNAME', dis%input_mempath, &
-                       found_fname)
-    !
     ! -- If disv enabled
     if (inunit > 0) then
       !
@@ -115,22 +114,13 @@ subroutine disv_cr(dis, name_model, input_mempath, inunit, iout)
       call disnew%disv_load()
     end if
     !
-    ! -- Return
-    return
   end subroutine disv_cr
 
+  !> @brief Transfer IDM data into this discretization object
+  !<
   subroutine disv_load(this)
-! ******************************************************************************
-! disv_load -- transfer data into this discretization object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfDisvType) :: this
-    ! -- locals
-! ------------------------------------------------------------------------------
     !
     ! -- source input data
     call this%source_options()
@@ -139,45 +129,23 @@ subroutine disv_load(this)
     call this%source_vertices()
     call this%source_cell2d()
     !
-    ! -- Return
-    return
   end subroutine disv_load
 
+  !> @brief Define the discretization
+  !<
   subroutine disv_df(this)
-! ******************************************************************************
-! disv_df -- Define
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfDisvType) :: this
-    ! -- locals
-! ------------------------------------------------------------------------------
     !
-    ! -- Final grid initialization
     call this%grid_finalize()
     !
-    ! -- Return
-    return
   end subroutine disv_df
 
+  !> @brief Deallocate variables
+  !<
   subroutine disv_da(this)
-! ******************************************************************************
-! disv_da -- Deallocate discretization data
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_deallocate
-    use MemoryManagerExtModule, only: memorylist_remove
-    use SimVariablesModule, only: idm_context
     ! -- dummy
     class(GwfDisvType) :: this
-    ! -- locals
-! ------------------------------------------------------------------------------
     !
     ! -- Deallocate idm memory
     call memorylist_remove(this%name_model, 'DISV', idm_context)
@@ -203,29 +171,17 @@ subroutine disv_da(this)
     call mem_deallocate(this%bot2d)
     call mem_deallocate(this%idomain)
     !
-    ! -- Return
-    return
   end subroutine disv_da
 
   !> @brief Copy options from IDM into package
   !<
   subroutine source_options(this)
-! ******************************************************************************
-! source_options -- source options from memory manager input path
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerExtModule, only: mem_set_value
-    use GwfDisvInputModule, only: GwfDisvParamFoundType
     ! -- dummy
     class(GwfDisvType) :: this
     ! -- locals
     character(len=LENVARNAME), dimension(3) :: lenunits = &
       &[character(len=LENVARNAME) :: 'FEET', 'METERS', 'CENTIMETERS']
     type(GwfDisvParamFoundType) :: found
-! ------------------------------------------------------------------------------
     !
     ! -- update defaults with idm sourced values
     call mem_set_value(this%lenuni, 'LENGTH_UNITS', this%input_mempath, &
@@ -240,62 +196,51 @@ subroutine source_options(this)
       call this%log_options(found)
     end if
     !
-    ! -- Return
-    return
   end subroutine source_options
 
   !> @brief Write user options to list file
   !<
   subroutine log_options(this, found)
-    use GwfDisvInputModule, only: GwfDisvParamFoundType
+    ! -- dummy
     class(GwfDisvType) :: this
     type(GwfDisvParamFoundType), intent(in) :: found
-
+    !
     write (this%iout, '(1x,a)') 'Setting Discretization Options'
-
+    !
     if (found%length_units) then
       write (this%iout, '(4x,a,i0)') 'Model length unit [0=UND, 1=FEET, &
       &2=METERS, 3=CENTIMETERS] set as ', this%lenuni
     end if
-
+    !
     if (found%nogrb) then
       write (this%iout, '(4x,a,i0)') 'Binary grid file [0=GRB, 1=NOGRB] &
         &set as ', this%nogrb
     end if
-
+    !
     if (found%xorigin) then
       write (this%iout, '(4x,a,G0)') 'XORIGIN = ', this%xorigin
     end if
-
+    !
     if (found%yorigin) then
       write (this%iout, '(4x,a,G0)') 'YORIGIN = ', this%yorigin
     end if
-
+    !
     if (found%angrot) then
       write (this%iout, '(4x,a,G0)') 'ANGROT = ', this%angrot
     end if
-
+    !
     write (this%iout, '(1x,a,/)') 'End Setting Discretization Options'
-
+    !
   end subroutine log_options
 
   !> @brief Copy dimensions from IDM into package
   !<
   subroutine source_dimensions(this)
-! ******************************************************************************
-! source_dimensions -- source dimensions from memory manager input path
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use MemoryManagerExtModule, only: mem_set_value
-    use GwfDisvInputModule, only: GwfDisvParamFoundType
     ! -- dummy
     class(GwfDisvType) :: this
     ! -- locals
     integer(I4B) :: j, k
     type(GwfDisvParamFoundType) :: found
-! ------------------------------------------------------------------------------
     !
     ! -- update defaults with idm sourced values
     call mem_set_value(this%nlay, 'NLAY', this%input_mempath, found%nlay)
@@ -345,51 +290,41 @@ subroutine source_dimensions(this)
       end do
     end do
     !
-    ! -- Return
-    return
   end subroutine source_dimensions
 
   !> @brief Write dimensions to list file
   !<
   subroutine log_dimensions(this, found)
-    use GwfDisvInputModule, only: GwfDisvParamFoundType
+    ! -- dummy
     class(GwfDisvType) :: this
     type(GwfDisvParamFoundType), intent(in) :: found
-
+    !
     write (this%iout, '(1x,a)') 'Setting Discretization Dimensions'
-
+    !
     if (found%nlay) then
       write (this%iout, '(4x,a,i0)') 'NLAY = ', this%nlay
     end if
-
+    !
     if (found%ncpl) then
       write (this%iout, '(4x,a,i0)') 'NCPL = ', this%ncpl
     end if
-
+    !
     if (found%nvert) then
       write (this%iout, '(4x,a,i0)') 'NVERT = ', this%nvert
     end if
-
+    !
     write (this%iout, '(1x,a,/)') 'End Setting Discretization Dimensions'
-
+    !
   end subroutine log_dimensions
 
+  !> @brief Copy grid data from IDM into package
+  !<
   subroutine source_griddata(this)
-! ******************************************************************************
-! source_griddata -- source griddata from memory manager input path
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerExtModule, only: mem_set_value
-    use GwfDisvInputModule, only: GwfDisvParamFoundType
     ! -- dummy
     class(GwfDisvType) :: this
     ! -- locals
     type(GwfDisvParamFoundType) :: found
     ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- update defaults with idm sourced values
     call mem_set_value(this%top1d, 'TOP', this%input_mempath, found%top)
@@ -401,50 +336,42 @@ subroutine source_griddata(this)
       call this%log_griddata(found)
     end if
     !
-    ! -- Return
-    return
   end subroutine source_griddata
 
   !> @brief Write griddata found to list file
   !<
   subroutine log_griddata(this, found)
-    use GwfDisvInputModule, only: GwfDisvParamFoundType
+    ! -- dummy
     class(GwfDisvType) :: this
     type(GwfDisvParamFoundType), intent(in) :: found
-
+    !
     write (this%iout, '(1x,a)') 'Setting Discretization Griddata'
-
+    !
     if (found%top) then
       write (this%iout, '(4x,a)') 'TOP set from input file'
     end if
-
+    !
     if (found%botm) then
       write (this%iout, '(4x,a)') 'BOTM set from input file'
     end if
-
+    !
     if (found%idomain) then
       write (this%iout, '(4x,a)') 'IDOMAIN set from input file'
     end if
-
+    !
     write (this%iout, '(1x,a,/)') 'End Setting Discretization Griddata'
-
+    !
   end subroutine log_griddata
 
+  !> @brief Finalize grid (check properties, allocate arrays, compute connections)
+  !<
   subroutine grid_finalize(this)
-! ******************************************************************************
-! grid_finalize -- Finalize grid
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfDisvType) :: this
     ! -- locals
     integer(I4B) :: node, noder, j, k
     real(DP) :: top
     real(DP) :: dz
-    character(len=300) :: ermsg
     ! -- formats
     character(len=*), parameter :: fmtdz = &
       "('CELL (',i0,',',i0,') THICKNESS <= 0. ', &
@@ -453,8 +380,6 @@ subroutine grid_finalize(this)
       "(/1x, 'The specified IDOMAIN results in a reduced number of cells.',&
       &/1x, 'Number of user nodes: ',I0,&
       &/1X, 'Number of nodes in solution: ', I0, //)"
-    ! -- data
-! ------------------------------------------------------------------------------
     !
     ! -- count active cells
     this%nodes = 0
@@ -484,8 +409,8 @@ subroutine grid_finalize(this)
           end if
           dz = top - this%bot2d(j, k)
           if (dz <= DZERO) then
-            write (ermsg, fmt=fmtdz) k, j, top, this%bot2d(j, k)
-            call store_error(ermsg)
+            write (errmsg, fmt=fmtdz) k, j, top, this%bot2d(j, k)
+            call store_error(errmsg)
           end if
         end if
       end do
@@ -563,27 +488,17 @@ subroutine grid_finalize(this)
     ! -- Build connections
     call this%connect()
     !
-    ! -- Return
-    return
   end subroutine grid_finalize
 
+  !> @brief Load grid vertices from IDM into package
+  !<
   subroutine source_vertices(this)
-! ******************************************************************************
-! source_vertices -- source vertex data from memory manager input path
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_setptr
     ! -- dummy
     class(GwfDisvType) :: this
     ! -- local
     integer(I4B) :: i
     real(DP), dimension(:), contiguous, pointer :: vert_x => null()
     real(DP), dimension(:), contiguous, pointer :: vert_y => null()
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- set pointers to memory manager input arrays
     call mem_setptr(vert_x, 'XV', this%input_mempath)
@@ -604,10 +519,10 @@ subroutine source_vertices(this)
       write (this%iout, '(1x,a)') 'Discretization Vertex data loaded'
     end if
     !
-    ! -- Return
-    return
   end subroutine source_vertices
 
+  !> @brief Build data structures to hold cell vertex info
+  !<
   subroutine define_cellverts(this, icell2d, ncvert, icvert)
     ! -- modules
     use SparseModule, only: sparsematrix
@@ -620,7 +535,6 @@ subroutine define_cellverts(this, icell2d, ncvert, icvert)
     type(sparsematrix) :: vert_spm
     integer(I4B) :: i, j, ierr
     integer(I4B) :: icv_idx, startvert, maxnnz = 5
-! ------------------------------------------------------------------------------
     !
     ! -- initialize sparse matrix
     call vert_spm%init(this%ncpl, this%nvert, maxnnz)
@@ -646,19 +560,11 @@ subroutine define_cellverts(this, icell2d, ncvert, icvert)
     call vert_spm%filliaja(this%iavert, this%javert, ierr)
     call vert_spm%destroy()
     !
-    ! -- Return
-    return
   end subroutine define_cellverts
 
+  !> @brief Copy cell2d data from IDM into package
+  !<
   subroutine source_cell2d(this)
-! ******************************************************************************
-! source_cell2d -- source cell2d data from memory manager input path
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_setptr
     ! -- dummy
     class(GwfDisvType) :: this
     ! -- locals
@@ -668,8 +574,6 @@ subroutine source_cell2d(this)
     real(DP), dimension(:), contiguous, pointer :: cell_x => null()
     real(DP), dimension(:), contiguous, pointer :: cell_y => null()
     integer(I4B) :: i
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- set pointers to input path ncvert and icvert
     call mem_setptr(icell2d, 'ICELL2D', this%input_mempath)
@@ -704,18 +608,11 @@ subroutine source_cell2d(this)
       write (this%iout, '(1x,a)') 'Discretization Cell2d data loaded'
     end if
     !
-    ! -- Return
-    return
   end subroutine source_cell2d
 
+  !> @brief Build grid connections
+  !<
   subroutine connect(this)
-! ******************************************************************************
-! connect -- Build grid connections
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfDisvType) :: this
     ! -- local
@@ -724,8 +621,6 @@ subroutine connect(this)
     integer(I4B) :: narea_eq_zero
     integer(I4B) :: narea_lt_zero
     real(DP) :: area
-    character(len=LINELENGTH) :: errmsg
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize
     narea_eq_zero = 0
@@ -740,14 +635,14 @@ subroutine connect(this)
       end do
       if (area < DZERO) then
         narea_lt_zero = narea_lt_zero + 1
-        write (errmsg, '(a,i0)') &
-          &'Calculated CELL2D area less than zero for cell ', j
+        write (errmsg, '(a,i0,a)') &
+          &'Calculated CELL2D area less than zero for cell ', j, '.'
         call store_error(errmsg)
       end if
       if (area == DZERO) then
         narea_eq_zero = narea_eq_zero + 1
-        write (errmsg, '(a,i0)') &
-          'Calculated CELL2D area is zero for cell ', j
+        write (errmsg, '(a,i0,a)') &
+          'Calculated CELL2D area is zero for cell ', j, '.'
         call store_error(errmsg)
       end if
     end do
@@ -755,16 +650,16 @@ subroutine connect(this)
     ! -- check for errors
     if (count_errors() > 0) then
       if (narea_lt_zero > 0) then
-        write (errmsg, '(i0, a)') narea_lt_zero, &
-          ' cell(s) have an area less than zero.  Calculated cell &
-          &areas must be greater than zero.  Negative areas often &
+        write (errmsg, '(i0,a)') narea_lt_zero, &
+          ' cell(s) have an area less than zero. Calculated cell &
+          &areas must be greater than zero. Negative areas often &
           &mean vertices are not listed in clockwise order.'
         call store_error(errmsg)
       end if
       if (narea_eq_zero > 0) then
-        write (errmsg, '(i0, a)') narea_eq_zero, &
-          ' cell(s) have an area equal to zero.  Calculated cell &
-          &areas must be greater than zero.  Calculated cell &
+        write (errmsg, '(i0,a)') narea_eq_zero, &
+          ' cell(s) have an area equal to zero. Calculated cell &
+          &areas must be greater than zero. Calculated cell &
           &areas equal to zero indicate that the cell is not defined &
           &by a valid polygon.'
         call store_error(errmsg)
@@ -785,20 +680,12 @@ subroutine connect(this)
     this%nja = this%con%nja
     this%njas = this%con%njas
     !
-    !
-    ! -- return
-    return
   end subroutine connect
 
+  !> @brief Write a binary grid file
+  !<
   subroutine write_grb(this, icelltype)
-! ******************************************************************************
-! write_grb -- Write the binary grid file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
-    use InputOutputModule, only: getunit, openfile
     use OpenSpecModule, only: access, form
     ! -- dummy
     class(GwfDisvType) :: this
@@ -809,10 +696,10 @@ subroutine write_grb(this, icelltype)
     character(len=50) :: txthdr
     character(len=lentxt) :: txt
     character(len=LINELENGTH) :: fname
+    ! -- formats
     character(len=*), parameter :: fmtgrdsave = &
       "(4X,'BINARY GRID INFORMATION WILL BE WRITTEN TO:', &
        &/,6X,'UNIT NUMBER: ', I0,/,6X, 'FILE NAME: ', A)"
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize
     ntxt = 20
@@ -927,20 +814,11 @@ subroutine write_grb(this, icelltype)
     ! -- Close the file
     close (iunit)
     !
-    ! -- return
-    return
   end subroutine write_grb
 
+  !> @brief Convert a user nodenumber to a string (nodenumber) or (k,j)
+  !<
   subroutine nodeu_to_string(this, nodeu, str)
-! ******************************************************************************
-! nodeu_to_string -- Convert user node number to a string in the form of
-! (nodenumber) or (k,j)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use InputOutputModule, only: get_ijk
     ! -- dummy
     class(GwfDisvType) :: this
     integer(I4B), intent(in) :: nodeu
@@ -948,7 +826,6 @@ subroutine nodeu_to_string(this, nodeu, str)
     ! -- local
     integer(I4B) :: i, j, k
     character(len=10) :: kstr, jstr
-! ------------------------------------------------------------------------------
     !
     call get_ijk(nodeu, 1, this%ncpl, this%nlay, i, j, k)
     write (kstr, '(i10)') k
@@ -956,35 +833,25 @@ subroutine nodeu_to_string(this, nodeu, str)
     str = '('//trim(adjustl(kstr))//','// &
           trim(adjustl(jstr))//')'
     !
-    ! -- return
-    return
   end subroutine nodeu_to_string
 
+  !> @brief Convert a user nodenumber to an array (nodenumber) or (k,j)
+  !<
   subroutine nodeu_to_array(this, nodeu, arr)
-! ******************************************************************************
-! nodeu_to_array -- Convert user node number to cellid and fill array with
-!                   (nodenumber) or (k, j) or (k,i,j)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use InputOutputModule, only: get_ijk
-    implicit none
+    ! -- dummy
     class(GwfDisvType) :: this
     integer(I4B), intent(in) :: nodeu
     integer(I4B), dimension(:), intent(inout) :: arr
     ! -- local
-    character(len=LINELENGTH) :: errmsg
     integer(I4B) :: isize
     integer(I4B) :: i, j, k
-! ------------------------------------------------------------------------------
     !
     ! -- check the size of arr
     isize = size(arr)
     if (isize /= this%ndim) then
       write (errmsg, '(a,i0,a,i0,a)') &
         'Program error: nodeu_to_array size of array (', isize, &
-        ') is not equal to the discretization dimension (', this%ndim, ')'
+        ') is not equal to the discretization dimension (', this%ndim, ').'
       call store_error(errmsg, terminate=.TRUE.)
     end if
     !
@@ -995,19 +862,11 @@ subroutine nodeu_to_array(this, nodeu, arr)
     arr(1) = k
     arr(2) = j
     !
-    ! -- return
-    return
   end subroutine nodeu_to_array
 
+  !> @brief Get reduced node number from user node number
+  !<
   function get_nodenumber_idx1(this, nodeu, icheck) result(nodenumber)
-! ******************************************************************************
-! get_nodenumber -- Return a nodenumber from the user specified node number
-!                   with an option to perform a check.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- return
     integer(I4B) :: nodenumber
     ! -- dummy
@@ -1015,18 +874,17 @@ function get_nodenumber_idx1(this, nodeu, icheck) result(nodenumber)
     integer(I4B), intent(in) :: nodeu
     integer(I4B), intent(in) :: icheck
     ! -- local
-    character(len=LINELENGTH) :: errmsg
-! ------------------------------------------------------------------------------
     !
     ! -- check the node number if requested
     if (icheck /= 0) then
       !
       ! -- If within valid range, convert to reduced nodenumber
       if (nodeu < 1 .or. nodeu > this%nodesuser) then
-        write (errmsg, '(a,i10)') &
-          'Nodenumber less than 1 or greater than nodes:', nodeu
-        call store_error(errmsg)
         nodenumber = 0
+        write (errmsg, '(a,i0,a,i0,a)') &
+          'Node number (', nodeu, ') is less than 1 or greater than nodes (', &
+          this%nodesuser, ').'
+        call store_error(errmsg)
       else
         nodenumber = nodeu
         if (this%nodes < this%nodesuser) nodenumber = this%nodereduced(nodeu)
@@ -1036,21 +894,11 @@ function get_nodenumber_idx1(this, nodeu, icheck) result(nodenumber)
       if (this%nodes < this%nodesuser) nodenumber = this%nodereduced(nodeu)
     end if
     !
-    ! -- return
-    return
   end function get_nodenumber_idx1
 
-  function get_nodenumber_idx2(this, k, j, icheck) &
-    result(nodenumber)
-! ******************************************************************************
-! get_nodenumber_idx2 -- Return a nodenumber from the user specified layer and
-!                       column with an option to perform a check.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use InputOutputModule, only: get_node
-    implicit none
+  !> @brief Get reduced node number from layer and within-layer node indices
+  !<
+  function get_nodenumber_idx2(this, k, j, icheck) result(nodenumber)
     ! -- return
     integer(I4B) :: nodenumber
     ! -- dummy
@@ -1058,12 +906,10 @@ function get_nodenumber_idx2(this, k, j, icheck) &
     integer(I4B), intent(in) :: k, j
     integer(I4B), intent(in) :: icheck
     ! -- local
-    character(len=LINELENGTH) :: errmsg
     integer(I4B) :: nodeu
-    ! formats
+    ! -- formats
     character(len=*), parameter :: fmterr = &
       &"('Error in disv grid cell indices: layer = ',i0,', node = ',i0)"
-! ------------------------------------------------------------------------------
     !
     nodeu = get_node(k, 1, j, this%nlay, 1, this%ncpl)
     if (nodeu < 1) then
@@ -1076,48 +922,51 @@ function get_nodenumber_idx2(this, k, j, icheck) &
     ! -- check the node number if requested
     if (icheck /= 0) then
       !
-      if (k < 1 .or. k > this%nlay) &
-        call store_error('Layer less than one or greater than nlay')
-      if (j < 1 .or. j > this%ncpl) &
-        call store_error('Node number less than one or greater than ncpl')
+      errmsg = ""
+      !
+      if (k < 1 .or. k > this%nlay) then
+        write (errmsg, '(a,i0,a)') &
+          'Layer number in list (', k, ') is outside of the grid.'
+      end if
+      if (j < 1 .or. j > this%ncpl) then
+        write (errmsg, '(a,1x,a,i0,a)') &
+          trim(adjustl(errmsg)), 'Node number in list (', j, &
+          ') is outside of the grid.'
+      end if
       !
       ! -- Error if outside of range
       if (nodeu < 1 .or. nodeu > this%nodesuser) then
-        write (errmsg, '(a,i10)') &
-          'Nodenumber less than 1 or greater than nodes:', nodeu
+        write (errmsg, '(a,1x,a,i0,a,i0,a)') &
+          trim(adjustl(errmsg)), &
+          'Node number (', nodeu, ') is less than 1 or greater '// &
+          'than nodes (', this%nodesuser, ').'
+      end if
+      !
+      if (len_trim(adjustl(errmsg)) > 0) then
         call store_error(errmsg)
       end if
+      !
     end if
     !
-    ! -- return
-    return
   end function get_nodenumber_idx2
 
+  !> @brief Get normal vector components between the cell and a given neighbor
+  !!
+  !! The normal points outward from the shared face between noden and nodem.
+  !<
   subroutine connection_normal(this, noden, nodem, ihc, xcomp, ycomp, zcomp, &
                                ipos)
-! ******************************************************************************
-! connection_normal -- calculate the normal vector components for reduced
-!   nodenumber cell (noden) and its shared face with cell nodem.  ihc is the
-!   horizontal connection flag.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfDisvType) :: this
-    integer(I4B), intent(in) :: noden
-    integer(I4B), intent(in) :: nodem
-    integer(I4B), intent(in) :: ihc
+    integer(I4B), intent(in) :: noden !< cell (reduced nn)
+    integer(I4B), intent(in) :: nodem !< neighbor (reduced nn)
+    integer(I4B), intent(in) :: ihc !< horizontal connection flag
     real(DP), intent(inout) :: xcomp
     real(DP), intent(inout) :: ycomp
     real(DP), intent(inout) :: zcomp
     integer(I4B), intent(in) :: ipos
     ! -- local
-    !integer(I4B) :: ipos
-    !integer(I4B) :: ncell3d, mcell3d
     real(DP) :: angle, dmult
-! ------------------------------------------------------------------------------
     !
     ! -- Set vector components based on ihc
     if (ihc == 0) then
@@ -1144,33 +993,23 @@ subroutine connection_normal(this, noden, nodem, ihc, xcomp, ycomp, zcomp, &
       zcomp = DZERO
     end if
     !
-    ! -- return
-    return
   end subroutine connection_normal
 
+  !> @brief Get unit vector components between the cell and a given neighbor
+  !!
+  !! Saturation must be provided to compute cell center vertical coordinates.
+  !! Also return the straight-line connection length.
+  !<
   subroutine connection_vector(this, noden, nodem, nozee, satn, satm, ihc, &
                                xcomp, ycomp, zcomp, conlen)
-! ******************************************************************************
-! connection_vector -- calculate the unit vector components from reduced
-!   nodenumber cell (noden) to its neighbor cell (nodem).  The saturation for
-!   for these cells are also required so that the vertical position of the cell
-!   cell centers can be calculated.  ihc is the horizontal flag.  Also return
-!   the straight-line connection length.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use InputOutputModule, only: get_jk
-    use DisvGeom, only: line_unit_vector
     ! -- dummy
     class(GwfDisvType) :: this
-    integer(I4B), intent(in) :: noden
-    integer(I4B), intent(in) :: nodem
+    integer(I4B), intent(in) :: noden !< cell (reduced nn)
+    integer(I4B), intent(in) :: nodem !< neighbor (reduced nn)
     logical, intent(in) :: nozee
     real(DP), intent(in) :: satn
     real(DP), intent(in) :: satm
-    integer(I4B), intent(in) :: ihc
+    integer(I4B), intent(in) :: ihc !< horizontal connection flag
     real(DP), intent(inout) :: xcomp
     real(DP), intent(inout) :: ycomp
     real(DP), intent(inout) :: zcomp
@@ -1178,7 +1017,6 @@ subroutine connection_vector(this, noden, nodem, nozee, satn, satm, ihc, &
     ! -- local
     integer(I4B) :: nodeu, ncell2d, mcell2d, k
     real(DP) :: xn, xm, yn, ym, zn, zm
-! ------------------------------------------------------------------------------
     !
     ! -- Set vector components based on ihc
     if (ihc == 0) then
@@ -1217,35 +1055,29 @@ subroutine connection_vector(this, noden, nodem, nozee, satn, satm, ihc, &
                             conlen)
     end if
     !
-    ! -- return
-    return
   end subroutine connection_vector
 
-  ! return discretization type
+  !> @brief Get the discretization type
+  !<
   subroutine get_dis_type(this, dis_type)
+    ! -- dummy
     class(GwfDisvType), intent(in) :: this
     character(len=*), intent(out) :: dis_type
-
+    !
     dis_type = "DISV"
-
+    !
   end subroutine get_dis_type
 
-  subroutine allocate_scalars(this, name_model)
-! ******************************************************************************
-! allocate_scalars -- Allocate and initialize scalars
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_allocate
+  !> @brief Allocate and initialize scalars
+  !<
+  subroutine allocate_scalars(this, name_model, input_mempath)
     ! -- dummy
     class(GwfDisvType) :: this
     character(len=*), intent(in) :: name_model
-! ------------------------------------------------------------------------------
+    character(len=*), intent(in) :: input_mempath
     !
     ! -- Allocate parent scalars
-    call this%DisBaseType%allocate_scalars(name_model)
+    call this%DisBaseType%allocate_scalars(name_model, input_mempath)
     !
     ! -- Allocate
     call mem_allocate(this%nlay, 'NLAY', this%memoryPath)
@@ -1258,22 +1090,13 @@ subroutine allocate_scalars(this, name_model)
     this%nvert = 0
     this%ndim = 2
     !
-    ! -- Return
-    return
   end subroutine allocate_scalars
 
+  !> @brief Allocate and initialize arrays
+  !<
   subroutine allocate_arrays(this)
-! ******************************************************************************
-! allocate_arrays -- Allocate arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwfDisvType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate arrays in DisBaseType (mshape, top, bot, area)
     call this%DisBaseType%allocate_arrays()
@@ -1291,21 +1114,16 @@ subroutine allocate_arrays(this)
     this%mshape(1) = this%nlay
     this%mshape(2) = this%ncpl
     !
-    ! -- Return
-    return
   end subroutine allocate_arrays
 
+  !> @brief Get the signed area of the cell
+  !!
+  !! A negative result means points are in counter-clockwise orientation.
+  !! Area is computed from the formula:
+  !! a = 1/2 *[(x1*y2 + x2*y3 + x3*y4 + ... + xn*y1) -
+  !!           (x2*y1 + x3*y2 + x4*y3 + ... + x1*yn)]
+  !<
   function get_cell2d_area(this, icell2d) result(area)
-! ******************************************************************************
-! get_cell2d_area -- Calculate and return the signed area of the cell.  A
-!   negative area means the points are in counter clockwise orientation.
-!   a = 1/2 *[(x1*y2 + x2*y3 + x3*y4 + ... + xn*y1) -
-!             (x2*y1 + x3*y2 + x4*y3 + ... + x1*yn)]
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- module
     ! -- dummy
     class(GwfDisvType) :: this
     integer(I4B), intent(in) :: icell2d
@@ -1315,13 +1133,18 @@ function get_cell2d_area(this, icell2d) result(area)
     integer(I4B) :: ivert
     integer(I4B) :: nvert
     integer(I4B) :: icount
+    integer(I4B) :: iv1
     real(DP) :: x
     real(DP) :: y
-! ------------------------------------------------------------------------------
+    real(DP) :: x1
+    real(DP) :: y1
     !
     area = DZERO
     nvert = this%iavert(icell2d + 1) - this%iavert(icell2d)
     icount = 1
+    iv1 = this%javert(this%iavert(icell2d))
+    x1 = this%vertices(1, iv1)
+    y1 = this%vertices(2, iv1)
     do ivert = this%iavert(icell2d), this%iavert(icell2d + 1) - 1
       x = this%vertices(1, this%javert(ivert))
       if (icount < nvert) then
@@ -1329,7 +1152,7 @@ function get_cell2d_area(this, icell2d) result(area)
       else
         y = this%vertices(2, this%javert(this%iavert(icell2d)))
       end if
-      area = area + x * y
+      area = area + (x - x1) * (y - y1)
       icount = icount + 1
     end do
     !
@@ -1341,28 +1164,22 @@ function get_cell2d_area(this, icell2d) result(area)
       else
         x = this%vertices(1, this%javert(this%iavert(icell2d)))
       end if
-      area = area - x * y
+      area = area - (x - x1) * (y - y1)
       icount = icount + 1
     end do
     !
     area = -DONE * area * DHALF
     !
-    ! -- return
-    return
   end function get_cell2d_area
 
+  !> @brief Convert a string to a user nodenumber
+  !!
+  !! Parse layer and within-layer cell number and return user nodenumber.
+  !! If flag_string is present and true, the first token may be
+  !! non-numeric (e.g. boundary name). In this case, return -2.
+  !<
   function nodeu_from_string(this, lloc, istart, istop, in, iout, line, &
                              flag_string, allow_zero) result(nodeu)
-! ******************************************************************************
-! nodeu_from_string -- Receive a string and convert the string to a user
-!   nodenumber.  The model discretization is DISV; read layer and cell number.
-!   If flag_string argument is present and true, the first token in string
-!   is allowed to be a string (e.g. boundary name). In this case, if a string
-!   is encountered, return value as -2.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfDisvType) :: this
     integer(I4B), intent(inout) :: lloc
@@ -1378,8 +1195,6 @@ function nodeu_from_string(this, lloc, istart, istop, in, iout, line, &
     integer(I4B) :: j, k, nlay, nrow, ncpl
     integer(I4B) :: lloclocal, ndum, istat, n
     real(DP) :: r
-    character(len=LINELENGTH) :: ermsg, fname
-! ------------------------------------------------------------------------------
     !
     if (present(flag_string)) then
       if (flag_string) then
@@ -1411,46 +1226,45 @@ function nodeu_from_string(this, lloc, istart, istop, in, iout, line, &
       end if
     end if
     !
+    errmsg = ''
+    !
     if (k < 1 .or. k > nlay) then
-      write (ermsg, *) ' Layer number in list is outside of the grid', k
-      call store_error(ermsg)
+      write (errmsg, '(a,i0,a)') &
+        'Layer number in list (', k, ') is outside of the grid.'
     end if
     if (j < 1 .or. j > ncpl) then
-      write (ermsg, *) ' Cell2d number in list is outside of the grid', j
-      call store_error(ermsg)
+      write (errmsg, '(a,1x,a,i0,a)') &
+        trim(adjustl(errmsg)), 'Cell2d number in list (', j, &
+        ') is outside of the grid.'
     end if
+    !
     nodeu = get_node(k, 1, j, nlay, nrow, ncpl)
     !
     if (nodeu < 1 .or. nodeu > this%nodesuser) then
-      write (ermsg, *) ' Node number in list is outside of the grid', nodeu
-      call store_error(ermsg)
-      inquire (unit=in, name=fname)
-      call store_error('Error converting in file: ')
-      call store_error(trim(adjustl(fname)))
-      call store_error('Cell number cannot be determined in line: ')
-      call store_error(trim(adjustl(line)))
+      write (errmsg, '(a,1x,a,i0,a)') &
+        trim(adjustl(errmsg)), &
+        "Node number in list (", nodeu, ") is outside of the grid. "// &
+        "Cell number cannot be determined in line '"// &
+        trim(adjustl(line))//"'."
+    end if
+    !
+    if (len_trim(adjustl(errmsg)) > 0) then
+      call store_error(errmsg)
       call store_error_unit(in)
     end if
     !
-    ! -- return
-    return
   end function nodeu_from_string
 
+  !> @brief Convert a cellid string to a user nodenumber
+  !!
+  !! If flag_string is present and true, the first token may be
+  !! non-numeric (e.g. boundary name). In this case, return -2.
+  !!
+  !! If allow_zero is present and true, and all indices are zero, the
+  !! result can be zero. If allow_zero is false, a zero in any index is an error.
+  !<
   function nodeu_from_cellid(this, cellid, inunit, iout, flag_string, &
                              allow_zero) result(nodeu)
-! ******************************************************************************
-! nodeu_from_cellid -- Receive cellid as a string and convert the string to a
-!   user nodenumber.
-!   If flag_string argument is present and true, the first token in string
-!   is allowed to be a string (e.g. boundary name). In this case, if a string
-!   is encountered, return value as -2.
-!   If allow_zero argument is present and true, if all indices equal zero, the
-!   result can be zero. If allow_zero is false, a zero in any index causes an
-!   error.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     integer(I4B) :: nodeu
     ! -- dummy
@@ -1465,8 +1279,6 @@ function nodeu_from_cellid(this, cellid, inunit, iout, flag_string, &
     integer(I4B) :: lloclocal, ndum, istat, n
     integer(I4B) :: istart, istop
     real(DP) :: r
-    character(len=LINELENGTH) :: ermsg, fname
-! ------------------------------------------------------------------------------
     !
     if (present(flag_string)) then
       if (flag_string) then
@@ -1499,70 +1311,108 @@ function nodeu_from_cellid(this, cellid, inunit, iout, flag_string, &
       end if
     end if
     !
+    errmsg = ''
+    !
     if (k < 1 .or. k > nlay) then
-      write (ermsg, *) ' Layer number in list is outside of the grid', k
-      call store_error(ermsg)
+      write (errmsg, '(a,i0,a)') &
+        'Layer number in list (', k, ') is outside of the grid.'
     end if
     if (j < 1 .or. j > ncpl) then
-      write (ermsg, *) ' Cell2d number in list is outside of the grid', j
-      call store_error(ermsg)
+      write (errmsg, '(a,1x,a,i0,a)') &
+        trim(adjustl(errmsg)), 'Cell2d number in list (', j, &
+        ') is outside of the grid.'
     end if
+    !
     nodeu = get_node(k, 1, j, nlay, nrow, ncpl)
     !
     if (nodeu < 1 .or. nodeu > this%nodesuser) then
-      write (ermsg, *) ' Node number in list is outside of the grid', nodeu
-      call store_error(ermsg)
-      inquire (unit=inunit, name=fname)
-      call store_error('Error converting in file: ')
-      call store_error(trim(adjustl(fname)))
-      call store_error('Cell number cannot be determined in cellid: ')
-      call store_error(trim(adjustl(cellid)))
+      write (errmsg, '(a,1x,a,i0,a)') &
+        trim(adjustl(errmsg)), &
+        "Cell number cannot be determined for cellid ("// &
+        trim(adjustl(cellid))//") and results in a user "// &
+        "node number (", nodeu, ") that is outside of the grid."
+    end if
+    !
+    if (len_trim(adjustl(errmsg)) > 0) then
+      call store_error(errmsg)
       call store_error_unit(inunit)
     end if
     !
-    ! -- return
-    return
   end function nodeu_from_cellid
 
+  !> @brief Indicates whether the grid discretization supports layers
+  !<
   logical function supports_layers(this)
-    implicit none
     ! -- dummy
     class(GwfDisvType) :: this
     !
     supports_layers = .true.
-    return
+    !
   end function supports_layers
 
+  !> @brief Get number of cells per layer (ncpl)
+  !<
   function get_ncpl(this)
-! ******************************************************************************
-! get_ncpl -- Return number of cells per layer.  This is ncpl
-!   for a DISV grid.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- return
     integer(I4B) :: get_ncpl
     ! -- dummy
     class(GwfDisvType) :: this
-! ------------------------------------------------------------------------------
     !
     get_ncpl = this%ncpl
     !
-    ! -- Return
-    return
   end function get_ncpl
 
+  !> @brief Get a 2D array of polygon vertices, listed in clockwise order
+  !! beginning with the lower left corner
+  !<
+  subroutine get_polyverts(this, ic, polyverts, closed)
+    ! -- dummy
+    class(GwfDisvType), intent(inout) :: this
+    integer(I4B), intent(in) :: ic !< cell number (reduced)
+    real(DP), allocatable, intent(out) :: polyverts(:, :) !< polygon vertices (column-major indexing)
+    logical(LGP), intent(in), optional :: closed !< whether to close the polygon, duplicating a vertex
+    ! -- local
+    integer(I4B) :: icu, icu2d, iavert, ncpl, nverts, m, j
+    logical(LGP) :: lclosed
+    !
+    ! count vertices
+    ncpl = this%get_ncpl()
+    icu = this%get_nodeuser(ic)
+    icu2d = icu - ((icu - 1) / ncpl) * ncpl
+    nverts = this%iavert(icu2d + 1) - this%iavert(icu2d) - 1
+    if (nverts .le. 0) nverts = nverts + size(this%javert)
+    !
+    ! check closed option
+    if (.not. (present(closed))) then
+      lclosed = .false.
+    else
+      lclosed = closed
+    end if
+    !
+    ! allocate vertices array
+    if (lclosed) then
+      allocate (polyverts(2, nverts + 1))
+    else
+      allocate (polyverts(2, nverts))
+    end if
+    !
+    ! set vertices
+    iavert = this%iavert(icu2d)
+    do m = 1, nverts
+      j = this%javert(iavert - 1 + m)
+      polyverts(:, m) = (/this%vertices(1, j), this%vertices(2, j)/)
+    end do
+    !
+    ! close if enabled
+    if (lclosed) &
+      polyverts(:, nverts + 1) = polyverts(:, 1)
+    !
+  end subroutine
+
+  !> @brief Read an integer array
+  !<
   subroutine read_int_array(this, line, lloc, istart, istop, iout, in, &
                             iarray, aname)
-! ******************************************************************************
-! read_int_array -- Read a GWF integer array
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfDisvType), intent(inout) :: this
     character(len=*), intent(inout) :: line
@@ -1581,7 +1431,6 @@ subroutine read_int_array(this, line, lloc, istart, istop, iout, in, &
     integer(I4B) :: ncol
     integer(I4B) :: nval
     integer(I4B), dimension(:), pointer, contiguous :: itemp
-! ------------------------------------------------------------------------------
     !
     ! -- Point the temporary pointer array, which is passed to the reading
     !    subroutine.  The temporary array will point to ibuff if it is a
@@ -1617,19 +1466,12 @@ subroutine read_int_array(this, line, lloc, istart, istop, iout, in, &
       call this%fill_grid_array(itemp, iarray)
     end if
     !
-    ! -- return
-    return
   end subroutine read_int_array
 
+  !> @brief Read a double precision array
+  !<
   subroutine read_dbl_array(this, line, lloc, istart, istop, iout, in, &
                             darray, aname)
-! ******************************************************************************
-! read_dbl_array -- Read a GWF double precision array
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfDisvType), intent(inout) :: this
     character(len=*), intent(inout) :: line
@@ -1648,7 +1490,6 @@ subroutine read_dbl_array(this, line, lloc, istart, istop, iout, in, &
     integer(I4B) :: ncol
     integer(I4B) :: nval
     real(DP), dimension(:), pointer, contiguous :: dtemp
-! ------------------------------------------------------------------------------
     !
     ! -- Point the temporary pointer array, which is passed to the reading
     !    subroutine.  The temporary array will point to dbuff if it is a
@@ -1684,22 +1525,15 @@ subroutine read_dbl_array(this, line, lloc, istart, istop, iout, in, &
       call this%fill_grid_array(dtemp, darray)
     end if
     !
-    ! -- return
-    return
   end subroutine read_dbl_array
 
+  !> @brief Read a 2d double array into col icolbnd of darray
+  !!
+  !! For cells that are outside of the active domain, do not copy the array
+  !! value into darray.
+  !<
   subroutine read_layer_array(this, nodelist, darray, ncolbnd, maxbnd, &
                               icolbnd, aname, inunit, iout)
-! ******************************************************************************
-! read_layer_array -- Read a 2d double array into col icolbnd of darray.
-!                     For cells that are outside of the active domain,
-!                     do not copy the array value into darray.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use InputOutputModule, only: get_node
     ! -- dummy
     class(GwfDisvType) :: this
     integer(I4B), intent(in) :: ncolbnd
@@ -1712,7 +1546,6 @@ subroutine read_layer_array(this, nodelist, darray, ncolbnd, maxbnd, &
     integer(I4B), intent(in) :: iout
     ! -- local
     integer(I4B) :: ir, ic, ncol, nrow, nlay, nval, ipos, nodeu
-! ------------------------------------------------------------------------------
     !
     ! -- set variables
     nlay = this%mshape(1)
@@ -1736,44 +1569,27 @@ subroutine read_layer_array(this, nodelist, darray, ncolbnd, maxbnd, &
       end do
     end do
     !
-    ! -- return
   end subroutine read_layer_array
 
+  !> @brief Record a double precision array
+  !!
+  !! The array is written to a formatted or unformatted external file depending
+  !! on the arguments.
+  !<
   subroutine record_array(this, darray, iout, iprint, idataun, aname, &
                           cdatafmp, nvaluesp, nwidthp, editdesc, dinact)
-! ******************************************************************************
-! record_array -- Record a double precision array.  The array will be
-!   printed to an external file and/or written to an unformatted external file
-!   depending on the argument specifications.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-!      darray is the double precision array to record
-!      iout is the unit number for ascii output
-!      iprint is a flag indicating whether or not to print the array
-!      idataun is the unit number to which the array will be written in binary
-!        form; if negative then do not write by layers, write entire array
-!      aname is the text descriptor of the array
-!      cdatafmp is the fortran format for writing the array
-!      nvaluesp is the number of values per line for printing
-!      nwidthp is the width of the number for printing
-!      editdesc is the format type (I, G, F, S, E)
-!      dinact is the double precision value to use for cells that are excluded
-!        from the model domain
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfDisvType), intent(inout) :: this
-    real(DP), dimension(:), pointer, contiguous, intent(inout) :: darray
-    integer(I4B), intent(in) :: iout
-    integer(I4B), intent(in) :: iprint
-    integer(I4B), intent(in) :: idataun
-    character(len=*), intent(in) :: aname
-    character(len=*), intent(in) :: cdatafmp
-    integer(I4B), intent(in) :: nvaluesp
-    integer(I4B), intent(in) :: nwidthp
-    character(len=*), intent(in) :: editdesc
-    real(DP), intent(in) :: dinact
+    real(DP), dimension(:), pointer, contiguous, intent(inout) :: darray !< double precision array to record
+    integer(I4B), intent(in) :: iout !< ascii output unit number
+    integer(I4B), intent(in) :: iprint !< whether to print the array
+    integer(I4B), intent(in) :: idataun !< binary output unit number, if negative don't write by layers, write entire array
+    character(len=*), intent(in) :: aname !< text descriptor
+    character(len=*), intent(in) :: cdatafmp !< write format
+    integer(I4B), intent(in) :: nvaluesp !< values per line
+    integer(I4B), intent(in) :: nwidthp !< number width
+    character(len=*), intent(in) :: editdesc !< format type (I, G, F, S, E)
+    real(DP), intent(in) :: dinact !< double precision value for cells excluded from model domain
     ! -- local
     integer(I4B) :: k, ifirst
     integer(I4B) :: nlay
@@ -1787,7 +1603,6 @@ subroutine record_array(this, darray, iout, iprint, idataun, aname, &
     character(len=*), parameter :: fmthsv = &
       "(1X,/1X,a,' WILL BE SAVED ON UNIT ',I4, &
        &' AT END OF TIME STEP',I5,', STRESS PERIOD ',I4)"
-! ------------------------------------------------------------------------------
     !
     ! -- set variables
     nlay = this%mshape(1)
@@ -1845,19 +1660,13 @@ subroutine record_array(this, darray, iout, iprint, idataun, aname, &
                   iout, delt, pertim, totim)
     end if
     !
-    ! -- return
-    return
   end subroutine record_array
 
+  !> @brief Record list header for imeth=6
+  !<
   subroutine record_srcdst_list_header(this, text, textmodel, textpackage, &
                                        dstmodel, dstpackage, naux, auxtxt, &
                                        ibdchn, nlist, iout)
-! ******************************************************************************
-! record_srcdst_list_header -- Record list header for imeth=6
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfDisvType) :: this
     character(len=16), intent(in) :: text
@@ -1872,7 +1681,6 @@ subroutine record_srcdst_list_header(this, text, textmodel, textpackage, &
     integer(I4B), intent(in) :: iout
     ! -- local
     integer(I4B) :: nlay, nrow, ncol
-! ------------------------------------------------------------------------------
     !
     nlay = this%mshape(1)
     nrow = 1
@@ -1883,34 +1691,20 @@ subroutine record_srcdst_list_header(this, text, textmodel, textpackage, &
                  ibdchn, naux, auxtxt, ncol, nrow, nlay, &
                  nlist, iout, delt, pertim, totim)
     !
-    ! -- return
-    return
   end subroutine record_srcdst_list_header
 
-  subroutine nlarray_to_nodelist(this, nodelist, maxbnd, nbound, aname, &
-                                 inunit, iout)
-! ******************************************************************************
-! nlarray_to_nodelist -- Read an integer array into nodelist. For structured
-!                        model, integer array is layer number; for unstructured
-!                        model, integer array is node number.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use InputOutputModule, only: get_node
+  !> @brief Convert an integer array (layer numbers) to nodelist
+  !<
+  subroutine nlarray_to_nodelist(this, darray, nodelist, maxbnd, nbound, aname)
     ! -- dummy
     class(GwfDisvType) :: this
     integer(I4B), intent(in) :: maxbnd
+    integer(I4B), dimension(:), pointer, contiguous :: darray
     integer(I4B), dimension(maxbnd), intent(inout) :: nodelist
     integer(I4B), intent(inout) :: nbound
     character(len=*), intent(in) :: aname
-    integer(I4B), intent(in) :: inunit
-    integer(I4B), intent(in) :: iout
     ! -- local
     integer(I4B) :: il, ir, ic, ncol, nrow, nlay, nval, nodeu, noder, ipos, ierr
-    character(len=LINELENGTH) :: errmsg
-! ------------------------------------------------------------------------------
     !
     ! -- set variables
     nlay = this%mshape(1)
@@ -1918,7 +1712,6 @@ subroutine nlarray_to_nodelist(this, nodelist, maxbnd, nbound, aname, &
     ncol = this%mshape(2)
     !
     nval = ncol * nrow
-    call ReadArray(inunit, this%ibuff, aname, this%ndim, nval, iout, 0)
     !
     ! -- Copy array into nodelist
     ipos = 1
@@ -1926,9 +1719,10 @@ subroutine nlarray_to_nodelist(this, nodelist, maxbnd, nbound, aname, &
     do ir = 1, nrow
       do ic = 1, ncol
         nodeu = get_node(1, ir, ic, nlay, nrow, ncol)
-        il = this%ibuff(nodeu)
+        il = darray(nodeu)
         if (il < 1 .or. il > nlay) then
-          write (errmsg, *) 'Invalid layer number: ', il
+          write (errmsg, '(a,i0,a)') &
+            'Invalid layer number (', il, ').'
           call store_error(errmsg, terminate=.TRUE.)
         end if
         nodeu = get_node(il, ir, ic, nlay, nrow, ncol)
@@ -1945,8 +1739,8 @@ subroutine nlarray_to_nodelist(this, nodelist, maxbnd, nbound, aname, &
     ! -- Check for errors
     nbound = ipos - 1
     if (ierr > 0) then
-      write (errmsg, '(a, i0)') &
-        'MAXBOUND dimension is too small.  Increase MAXBOUND to ', ierr
+      write (errmsg, '(a,i0,a)') &
+        'MAXBOUND dimension is too small. Increase MAXBOUND to ', ierr, '.'
       call store_error(errmsg, terminate=.TRUE.)
     end if
     !
@@ -1957,7 +1751,6 @@ subroutine nlarray_to_nodelist(this, nodelist, maxbnd, nbound, aname, &
       end do
     end if
     !
-    ! -- return
   end subroutine nlarray_to_nodelist
 
 end module GwfDisvModule
diff --git a/src/Model/GroundWaterFlow/gwf3disv8idm.f90 b/src/Model/GroundWaterFlow/gwf3disv8idm.f90
index 142d32945d7..657d138186f 100644
--- a/src/Model/GroundWaterFlow/gwf3disv8idm.f90
+++ b/src/Model/GroundWaterFlow/gwf3disv8idm.f90
@@ -1,5 +1,6 @@
 ! ** Do Not Modify! MODFLOW 6 system generated file. **
 module GwfDisvInputModule
+  use ConstantsModule, only: LENVARNAME
   use InputDefinitionModule, only: InputParamDefinitionType, &
                                    InputBlockDefinitionType
   private
@@ -46,7 +47,8 @@ module GwfDisvInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -62,7 +64,8 @@ module GwfDisvInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -78,7 +81,8 @@ module GwfDisvInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -94,7 +98,8 @@ module GwfDisvInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -110,7 +115,8 @@ module GwfDisvInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -126,7 +132,8 @@ module GwfDisvInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -142,7 +149,8 @@ module GwfDisvInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -158,7 +166,8 @@ module GwfDisvInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -174,7 +183,8 @@ module GwfDisvInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -190,7 +200,8 @@ module GwfDisvInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -206,7 +217,8 @@ module GwfDisvInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -222,7 +234,8 @@ module GwfDisvInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -238,7 +251,8 @@ module GwfDisvInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -254,7 +268,8 @@ module GwfDisvInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -270,7 +285,8 @@ module GwfDisvInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -286,7 +302,8 @@ module GwfDisvInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -302,7 +319,8 @@ module GwfDisvInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -318,7 +336,8 @@ module GwfDisvInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -334,7 +353,8 @@ module GwfDisvInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -374,7 +394,8 @@ module GwfDisvInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -390,7 +411,8 @@ module GwfDisvInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
diff --git a/src/Model/GroundWaterFlow/gwf3drn8.f90 b/src/Model/GroundWaterFlow/gwf3drn8.f90
index c0b5562c555..64a7f1240d3 100644
--- a/src/Model/GroundWaterFlow/gwf3drn8.f90
+++ b/src/Model/GroundWaterFlow/gwf3drn8.f90
@@ -2,13 +2,14 @@ module DrnModule
   use KindModule, only: DP, I4B
   use ConstantsModule, only: DZERO, DONE, DTWO, &
                              LENFTYPE, LENPACKAGENAME, LENAUXNAME, LINELENGTH
+  use SimVariablesModule, only: errmsg
+  use SimModule, only: count_errors, store_error, store_error_filename
   use MemoryHelperModule, only: create_mem_path
   use SmoothingModule, only: sQSaturation, sQSaturationDerivative, &
                              sQuadraticSaturation
   use BndModule, only: BndType
+  use BndExtModule, only: BndExtType
   use ObsModule, only: DefaultObsIdProcessor
-  use TimeSeriesLinkModule, only: TimeSeriesLinkType, &
-                                  GetTimeSeriesLinkFromList
   use MatrixBaseModule
   !
   implicit none
@@ -20,14 +21,20 @@ module DrnModule
   character(len=LENFTYPE) :: ftype = 'DRN'
   character(len=LENPACKAGENAME) :: text = '             DRN'
   !
-  type, extends(BndType) :: DrnType
+  type, extends(BndExtType) :: DrnType
 
+    real(DP), dimension(:), pointer, contiguous :: elev => null() !< DRN elevation
+    real(DP), dimension(:), pointer, contiguous :: cond => null() !< DRN conductance at aquifer interface
     integer(I4B), pointer :: iauxddrncol => null()
     integer(I4B), pointer :: icubic_scaling => null()
 
   contains
+
     procedure :: allocate_scalars => drn_allocate_scalars
-    procedure :: bnd_options => drn_options
+    procedure :: allocate_arrays => drn_allocate_arrays
+    procedure :: source_options => drn_options
+    procedure :: log_drn_options
+    procedure :: bnd_rp => drn_rp
     procedure :: bnd_ck => drn_ck
     procedure :: bnd_cf => drn_cf
     procedure :: bnd_fc => drn_fc
@@ -36,24 +43,20 @@ module DrnModule
     procedure :: define_listlabel
     procedure :: get_drain_elevations
     procedure :: get_drain_factor
+    procedure :: bound_value => drn_bound_value
+    procedure :: cond_mult
     ! -- methods for observations
     procedure, public :: bnd_obs_supported => drn_obs_supported
     procedure, public :: bnd_df_obs => drn_df_obs
-    ! -- method for time series
-    procedure, public :: bnd_rp_ts => drn_rp_ts
+    procedure, public :: drn_store_user_cond
   end type DrnType
 
 contains
 
-  subroutine drn_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
-! ******************************************************************************
-! drn_create -- Create a New Drn Package
-! Subroutine: (1) create new-style package
-!             (2) point packobj to the new package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Create a New Drn Package and point packobj to the new package
+  !<
+  subroutine drn_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
+                        mempath)
     ! -- dummy
     class(BndType), pointer :: packobj
     integer(I4B), intent(in) :: id
@@ -62,16 +65,16 @@ subroutine drn_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     integer(I4B), intent(in) :: iout
     character(len=*), intent(in) :: namemodel
     character(len=*), intent(in) :: pakname
+    character(len=*), intent(in) :: mempath
     ! -- local
     type(DrnType), pointer :: drnobj
-! ------------------------------------------------------------------------------
     !
     ! -- allocate the object and assign values to object variables
     allocate (drnobj)
     packobj => drnobj
     !
     ! -- create name and memory path
-    call packobj%set_names(ibcnum, namemodel, pakname, ftype)
+    call packobj%set_names(ibcnum, namemodel, pakname, ftype, mempath)
     packobj%text = text
     !
     ! -- allocate scalars
@@ -85,52 +88,45 @@ subroutine drn_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     packobj%iout = iout
     packobj%id = id
     packobj%ibcnum = ibcnum
-    packobj%ncolbnd = 2 ! drnelev, conductance
-    packobj%iscloc = 2 !sfac applies to conductance
     packobj%ictMemPath = create_mem_path(namemodel, 'NPF')
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine drn_create
 
+  !> @brief Deallocate memory
+  !<
   subroutine drn_da(this)
-! ******************************************************************************
-! drn_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(DrnType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Deallocate parent package
-    call this%BndType%bnd_da()
+    call this%BndExtType%bnd_da()
     !
     ! -- scalars
     call mem_deallocate(this%iauxddrncol)
     call mem_deallocate(this%icubic_scaling)
     !
-    ! -- return
+    ! -- arrays
+    call mem_deallocate(this%elev, 'ELEV', this%memoryPath)
+    call mem_deallocate(this%cond, 'COND', this%memoryPath)
+    !
+    ! -- Return
     return
   end subroutine drn_da
 
+  !> @brief Allocate package scalar members
+  !<
   subroutine drn_allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars -- allocate scalar members
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(DrnType) :: this
-! ------------------------------------------------------------------------------
     !
-    ! -- call standard BndType allocate scalars
-    call this%BndType%allocate_scalars()
+    ! -- call base type allocate scalars
+    call this%BndExtType%allocate_scalars()
     !
     ! -- allocate the object and assign values to object variables
     call mem_allocate(this%iauxddrncol, 'IAUXDDRNCOL', this%memoryPath)
@@ -144,60 +140,90 @@ subroutine drn_allocate_scalars(this)
       this%icubic_scaling = 0
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine drn_allocate_scalars
 
-  subroutine drn_options(this, option, found)
-! ******************************************************************************
-! drn_options -- set options specific to DrnType
-!
-! drn_options overrides BndType%bnd_options
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Allocate package arrays
+  !<
+  subroutine drn_allocate_arrays(this, nodelist, auxvar)
+    ! -- modules
+    use MemoryManagerModule, only: mem_allocate, mem_setptr, mem_checkin
+    ! -- dummy
+    class(DrnType) :: this
+    integer(I4B), dimension(:), pointer, contiguous, optional :: nodelist
+    real(DP), dimension(:, :), pointer, contiguous, optional :: auxvar
+    !
+    ! -- call base type allocate arrays
+    call this%BndExtType%allocate_arrays(nodelist, auxvar)
+    !
+    ! -- set drn input context pointers
+    call mem_setptr(this%elev, 'ELEV', this%input_mempath)
+    call mem_setptr(this%cond, 'COND', this%input_mempath)
+    !
+    ! --checkin drn input context pointers
+    call mem_checkin(this%elev, 'ELEV', this%memoryPath, &
+                     'ELEV', this%input_mempath)
+    call mem_checkin(this%cond, 'COND', this%memoryPath, &
+                     'COND', this%input_mempath)
+    !
+    ! -- Return
+    return
+  end subroutine drn_allocate_arrays
+
+  !> @brief Read and prepare
+  !<
+  subroutine drn_rp(this)
+    use TdisModule, only: kper
+    ! -- dummy
+    class(DrnType), intent(inout) :: this
+    !
+    if (this%iper /= kper) return
+    !
+    ! -- Call the parent class read and prepare
+    call this%BndExtType%bnd_rp()
+    !
+    ! -- store user cond
+    if (this%ivsc == 1) then
+      call this%drn_store_user_cond()
+    end if
+    !
+    ! -- Write the list to iout if requested
+    if (this%iprpak /= 0) then
+      call this%write_list()
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine drn_rp
+
+  !> @brief Source options specific to DrnType
+  !<
+  subroutine drn_options(this)
+    ! -- modules
     use InputOutputModule, only: urword
-    use SimModule, only: store_error
+    use MemoryManagerExtModule, only: mem_set_value
+    use CharacterStringModule, only: CharacterStringType
+    use GwfDrnInputModule, only: GwfDrnParamFoundType
     ! -- dummy
     class(DrnType), intent(inout) :: this
-    character(len=*), intent(inout) :: option
-    logical, intent(inout) :: found
     ! -- local
-    character(len=LINELENGTH) :: errmsg
+    type(GwfDrnParamFoundType) :: found
     character(len=LENAUXNAME) :: ddrnauxname
     integer(I4B) :: n
-! ------------------------------------------------------------------------------
     !
-    found = .true.
-    select case (option)
-    case ('MOVER')
-      this%imover = 1
-      write (this%iout, '(4x,A)') 'MOVER OPTION ENABLED'
-    case ('AUXDEPTHNAME')
-      call this%parser%GetStringCaps(ddrnauxname)
-      this%iauxddrncol = -1
-      write (this%iout, '(4x,a,a)') &
-        'AUXILIARY DRAIN DEPTH NAME: ', trim(ddrnauxname)
-      !
-      ! -- right now these are options that are only available in the
-      !    development version and are not included in the documentation.
-      !    These options are only available when IDEVELOPMODE in
-      !    constants module is set to 1
-    case ('DEV_CUBIC_SCALING')
-      call this%parser%DevOpt()
-      this%icubic_scaling = 1
-      write (this%iout, '(4x,a,1x,a)') &
-        'CUBIC SCALING will be used for drains with non-zero DDRN values', &
-        'even if the NEWTON-RAPHSON method is not being used.'
-    case default
-      !
-      ! -- No options found
-      found = .false.
-    end select
+    ! -- source base class options
+    call this%BndExtType%source_options()
     !
-    ! -- DDRN was specified, so find column of auxvar that will be used
-    if (this%iauxddrncol < 0) then
+    ! -- source drain options
+    call mem_set_value(this%imover, 'MOVER', this%input_mempath, found%mover)
+    call mem_set_value(ddrnauxname, 'AUXDEPTHNAME', this%input_mempath, &
+                       found%auxdepthname)
+    call mem_set_value(this%icubic_scaling, 'ICUBICSFAC', this%input_mempath, &
+                       found%icubicsfac)
+    !
+    if (found%auxdepthname) then
+      this%iauxddrncol = -1
       !
       ! -- Error if no aux variable specified
       if (this%naux == 0) then
@@ -225,24 +251,56 @@ subroutine drn_options(this, option, found)
       end if
     end if
     !
-    ! -- return
+    if (found%icubicsfac) then
+      call this%parser%DevOpt()
+    end if
+    !
+    ! -- log DRN specific options
+    call this%log_drn_options(found)
+    !
+    ! -- Return
     return
   end subroutine drn_options
 
-  subroutine drn_ck(this)
-! ******************************************************************************
-! drn_ck -- Check drain boundary condition data
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @ brief Log DRN specific package options
+  !<
+  subroutine log_drn_options(this, found)
     ! -- modules
-    use ConstantsModule, only: LINELENGTH
-    use SimModule, only: store_error, count_errors, store_error_unit
+    use GwfDrnInputModule, only: GwfDrnParamFoundType
+    ! -- dummy variables
+    class(DrnType), intent(inout) :: this !< BndExtType object
+    type(GwfDrnParamFoundType), intent(in) :: found
+    ! -- local variables
+    ! -- format
+    !
+    ! -- log found options
+    write (this%iout, '(/1x,a)') 'PROCESSING '//trim(adjustl(this%text)) &
+      //' OPTIONS'
+    !
+    if (found%mover) then
+      write (this%iout, '(4x,A)') 'MOVER OPTION ENABLED'
+    end if
+    !
+    if (found%icubicsfac) then
+      write (this%iout, '(4x,a,1x,a)') &
+        'CUBIC SCALING will be used for drains with non-zero DDRN values', &
+        'even if the NEWTON-RAPHSON method is not being used.'
+    end if
+    !
+    ! -- close logging block
+    write (this%iout, '(1x,a)') &
+      'END OF '//trim(adjustl(this%text))//' OPTIONS'
+    !
+    ! -- Return
+    return
+  end subroutine log_drn_options
+
+  !> @brief Check drain boundary condition data
+  !<
+  subroutine drn_ck(this)
     ! -- dummy
     class(DrnType), intent(inout) :: this
     ! -- local
-    character(len=LINELENGTH) :: errmsg
     integer(I4B) :: i
     integer(I4B) :: node
     real(DP) :: bt
@@ -256,7 +314,6 @@ subroutine drn_ck(this)
     character(len=*), parameter :: fmtdrnerr = &
       "('DRN BOUNDARY (',i0,') ELEVATION (',f10.3,') IS LESS THAN CELL &
       &BOTTOM (',f10.3,')')"
-! ------------------------------------------------------------------------------
     !
     ! -- check stress period data
     do i = 1, this%nbound
@@ -280,44 +337,30 @@ subroutine drn_ck(this)
     !
     ! -- write summary of drain package error messages
     if (count_errors() > 0) then
-      call store_error_unit(this%inunit)
+      call store_error_filename(this%input_fname)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine drn_ck
 
-  subroutine drn_cf(this, reset_mover)
-! ******************************************************************************
-! drn_cf -- Formulate the HCOF and RHS terms
-! Subroutine: (1) skip if no drains
-!             (2) calculate hcof and rhs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Formulate the HCOF and RHS terms
+  !!
+  !! Skip if no drains
+  !<
+  subroutine drn_cf(this)
     ! -- dummy
     class(DrnType) :: this
-    logical, intent(in), optional :: reset_mover
     ! -- local
     integer(I4B) :: i
     integer(I4B) :: node
     real(DP) :: cdrn
     real(DP) :: drnbot
     real(DP) :: fact
-    logical :: lrm
-! ------------------------------------------------------------------------------
     !
     ! -- Return if no drains
     if (this%nbound == 0) return
     !
-    ! -- pakmvrobj cf
-    lrm = .true.
-    if (present(reset_mover)) lrm = reset_mover
-    if (this%imover == 1 .and. lrm) then
-      call this%pakmvrobj%cf()
-    end if
-    !
     ! -- Calculate hcof and rhs for each drn entry
     do i = 1, this%nbound
       node = this%nodelist(i)
@@ -328,7 +371,8 @@ subroutine drn_cf(this, reset_mover)
       end if
       !
       ! -- set local variables for this drain
-      cdrn = this%bound(2, i)
+      cdrn = this%cond_mult(i)
+
       !
       ! -- calculate the drainage scaling factor
       call this%get_drain_factor(i, fact, drnbot)
@@ -338,17 +382,13 @@ subroutine drn_cf(this, reset_mover)
       this%hcof(i) = -fact * cdrn
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine drn_cf
 
+  !> @brief Copy rhs and hcof into solution rhs and amat
+  !<
   subroutine drn_fc(this, rhs, ia, idxglo, matrix_sln)
-! **************************************************************************
-! drn_fc -- Copy rhs and hcof into solution rhs and amat
-! **************************************************************************
-!
-!    SPECIFICATIONS:
-! --------------------------------------------------------------------------
     ! -- dummy
     class(DrnType) :: this
     real(DP), dimension(:), intent(inout) :: rhs
@@ -363,7 +403,6 @@ subroutine drn_fc(this, rhs, ia, idxglo, matrix_sln)
     real(DP) :: drnbot
     real(DP) :: drncond
     real(DP) :: qdrn
-! --------------------------------------------------------------------------
     !
     ! -- packmvrobj fc
     if (this%imover == 1) then
@@ -383,23 +422,19 @@ subroutine drn_fc(this, rhs, ia, idxglo, matrix_sln)
       ! -- If mover is active and this drain is discharging,
       !    store available water (as positive value).
       if (this%imover == 1 .and. fact > DZERO) then
-        drncond = this%bound(2, i)
+        drncond = this%cond_mult(i)
         qdrn = fact * drncond * (this%xnew(n) - drnbot)
         call this%pakmvrobj%accumulate_qformvr(i, qdrn)
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine drn_fc
 
+  !> @brief Fill newton terms
+  !<
   subroutine drn_fn(this, rhs, ia, idxglo, matrix_sln)
-! **************************************************************************
-! drn_fn -- Fill newton terms
-! **************************************************************************
-!
-!    SPECIFICATIONS:
-! --------------------------------------------------------------------------
     implicit none
     ! -- dummy
     class(DrnType) :: this
@@ -417,8 +452,6 @@ subroutine drn_fn(this, rhs, ia, idxglo, matrix_sln)
     real(DP) :: drntop
     real(DP) :: drnbot
     real(DP) :: drterm
-! --------------------------------------------------------------------------
-
     !
     ! -- Copy package rhs and hcof into solution rhs and amat
     if (this%iauxddrncol /= 0) then
@@ -431,7 +464,7 @@ subroutine drn_fn(this, rhs, ia, idxglo, matrix_sln)
         end if
         !
         ! -- set local variables for this drain
-        cdrn = this%bound(2, i)
+        cdrn = this%cond_mult(i)
         xnew = this%xnew(node)
         !
         ! -- calculate the drainage depth and the top and bottom of
@@ -452,20 +485,16 @@ subroutine drn_fn(this, rhs, ia, idxglo, matrix_sln)
       end do
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine drn_fn
 
+  !> @brief Define the list heading that is written to iout when PRINT_INPUT
+  !! option is used
+  !<
   subroutine define_listlabel(this)
-! ******************************************************************************
-! define_listlabel -- Define the list heading that is written to iout when
-!   PRINT_INPUT option is used.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     class(DrnType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- create the header list label
     this%listlabel = trim(this%filtyp)//' NO.'
@@ -485,18 +514,14 @@ subroutine define_listlabel(this)
       write (this%listlabel, '(a, a16)') trim(this%listlabel), 'BOUNDARY NAME'
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine define_listlabel
 
+  !> @brief Define drain depth and the top and bottom elevations used to scale
+  !! the drain conductance
+  !<
   subroutine get_drain_elevations(this, i, drndepth, drntop, drnbot)
-! ******************************************************************************
-! get_drain_elevations -- Define drain depth and the top and bottom elevations
-!                         used to scale the drain conductance.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(DrnType), intent(inout) :: this
     integer(I4B), intent(in) :: i
@@ -506,11 +531,10 @@ subroutine get_drain_elevations(this, i, drndepth, drntop, drnbot)
     ! -- local
     real(DP) :: drnelev
     real(DP) :: elev
-! ------------------------------------------------------------------------------
     !
     ! -- initialize dummy and local variables
     drndepth = DZERO
-    drnelev = this%bound(1, i)
+    drnelev = this%elev(i)
     !
     ! -- set the drain depth
     if (this%iauxddrncol > 0) then
@@ -527,17 +551,13 @@ subroutine get_drain_elevations(this, i, drndepth, drntop, drnbot)
       drnbot = drnelev
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine get_drain_elevations
 
+  !> @brief Get the drain conductance scale factor
+  !<
   subroutine get_drain_factor(this, i, factor, opt_drnbot)
-! ******************************************************************************
-! get_drain_factor -- Get the drain conductance scale factor.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(DrnType), intent(inout) :: this
     integer(I4B), intent(in) :: i
@@ -549,7 +569,6 @@ subroutine get_drain_factor(this, i, factor, opt_drnbot)
     real(DP) :: drndepth
     real(DP) :: drntop
     real(DP) :: drnbot
-! ------------------------------------------------------------------------------
     !
     ! -- set local variables for this drain
     node = this%nodelist(i)
@@ -579,45 +598,38 @@ subroutine get_drain_factor(this, i, factor, opt_drnbot)
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine get_drain_factor
 
   ! -- Procedures related to observations
 
+  !> @brief Return true because DRN package supports observations
+  !!
+  !! Overrides BndType%bnd_obs_supported()
+  !<
   logical function drn_obs_supported(this)
-! ******************************************************************************
-! drn_obs_supported
-!   -- Return true because DRN package supports observations.
-!   -- Overrides BndType%bnd_obs_supported()
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     implicit none
+    ! -- dummy
     class(DrnType) :: this
-! ------------------------------------------------------------------------------
+    !
     drn_obs_supported = .true.
     !
-    ! -- return
+    ! -- Return
     return
   end function drn_obs_supported
 
+  !> @brief Store observation type supported by DRN package
+  !!
+  !! Overrides BndType%bnd_df_obs
+  !<
   subroutine drn_df_obs(this)
-! ******************************************************************************
-! drn_df_obs (implements bnd_df_obs)
-!   -- Store observation type supported by DRN package.
-!   -- Overrides BndType%bnd_df_obs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     implicit none
     ! -- dummy
     class(DrnType) :: this
     ! -- local
     integer(I4B) :: indx
-! ------------------------------------------------------------------------------
+    !
     call this%obs%StoreObsType('drn', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => DefaultObsIdProcessor
     !
@@ -626,37 +638,74 @@ subroutine drn_df_obs(this)
     call this%obs%StoreObsType('to-mvr', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => DefaultObsIdProcessor
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine drn_df_obs
 
-  ! -- Procedure related to time series
-
-  subroutine drn_rp_ts(this)
-    ! -- Assign tsLink%Text appropriately for
-    !    all time series in use by package.
-    !    In DRN package variables ELEV and COND
-    !    can be controlled by time series.
+  !> @brief Store user-specified drain conductance
+  !<
+  subroutine drn_store_user_cond(this)
     ! -- dummy
-    class(DrnType), intent(inout) :: this
+    class(DrnType), intent(inout) :: this !< BndExtType object
     ! -- local
-    integer(I4B) :: i, nlinks
-    type(TimeSeriesLinkType), pointer :: tslink => null()
-    !
-    nlinks = this%TsManager%boundtslinks%Count()
-    do i = 1, nlinks
-      tslink => GetTimeSeriesLinkFromList(this%TsManager%boundtslinks, i)
-      if (associated(tslink)) then
-        select case (tslink%JCol)
-        case (1)
-          tslink%Text = 'ELEV'
-        case (2)
-          tslink%Text = 'COND'
-        end select
-      end if
+    integer(I4B) :: n
+    !
+    ! -- store backup copy of conductance values
+    do n = 1, this%nbound
+      this%condinput(n) = this%cond_mult(n)
     end do
     !
+    ! -- Return
+    return
+  end subroutine drn_store_user_cond
+
+  !> @brief Apply multiplier to conductance value depending on user-selected option
+  !<
+  function cond_mult(this, row) result(cond)
+    ! -- modules
+    use ConstantsModule, only: DZERO
+    ! -- dummy variables
+    class(DrnType), intent(inout) :: this !< BndExtType object
+    integer(I4B), intent(in) :: row
+    ! -- result
+    real(DP) :: cond
+    !
+    if (this%iauxmultcol > 0) then
+      cond = this%cond(row) * this%auxvar(this%iauxmultcol, row)
+    else
+      cond = this%cond(row)
+    end if
+    !
+    ! -- Return
+    return
+  end function cond_mult
+
+  !> @brief Return requested boundary value
+  !<
+  function drn_bound_value(this, col, row) result(bndval)
+    ! -- modules
+    use ConstantsModule, only: DZERO
+    ! -- dummy variables
+    class(DrnType), intent(inout) :: this !< BndExtType object
+    integer(I4B), intent(in) :: col
+    integer(I4B), intent(in) :: row
+    ! -- result
+    real(DP) :: bndval
+    !
+    select case (col)
+    case (1)
+      bndval = this%elev(row)
+    case (2)
+      bndval = this%cond_mult(row)
+    case default
+      errmsg = 'Programming error. DRN bound value requested column '&
+               &'outside range of ncolbnd (2).'
+      call store_error(errmsg)
+      call store_error_filename(this%input_fname)
+    end select
+    !
+    ! -- Return
     return
-  end subroutine drn_rp_ts
+  end function drn_bound_value
 
 end module DrnModule
diff --git a/src/Model/GroundWaterFlow/gwf3drn8idm.f90 b/src/Model/GroundWaterFlow/gwf3drn8idm.f90
new file mode 100644
index 00000000000..ddd87932b4c
--- /dev/null
+++ b/src/Model/GroundWaterFlow/gwf3drn8idm.f90
@@ -0,0 +1,487 @@
+! ** Do Not Modify! MODFLOW 6 system generated file. **
+module GwfDrnInputModule
+  use ConstantsModule, only: LENVARNAME
+  use InputDefinitionModule, only: InputParamDefinitionType, &
+                                   InputBlockDefinitionType
+  private
+  public gwf_drn_param_definitions
+  public gwf_drn_aggregate_definitions
+  public gwf_drn_block_definitions
+  public GwfDrnParamFoundType
+  public gwf_drn_multi_package
+
+  type GwfDrnParamFoundType
+    logical :: auxiliary = .false.
+    logical :: auxmultname = .false.
+    logical :: auxdepthname = .false.
+    logical :: boundnames = .false.
+    logical :: iprpak = .false.
+    logical :: iprflow = .false.
+    logical :: ipakcb = .false.
+    logical :: ts_filerecord = .false.
+    logical :: ts6 = .false.
+    logical :: filein = .false.
+    logical :: ts6_filename = .false.
+    logical :: obs_filerecord = .false.
+    logical :: obs6 = .false.
+    logical :: obs6_filename = .false.
+    logical :: mover = .false.
+    logical :: icubicsfac = .false.
+    logical :: maxbound = .false.
+    logical :: cellid = .false.
+    logical :: elev = .false.
+    logical :: cond = .false.
+    logical :: auxvar = .false.
+    logical :: boundname = .false.
+  end type GwfDrnParamFoundType
+
+  logical :: gwf_drn_multi_package = .true.
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_auxiliary = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXILIARY', & ! tag name
+    'AUXILIARY', & ! fortran variable
+    'STRING', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_auxmultname = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXMULTNAME', & ! tag name
+    'AUXMULTNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_auxdepthname = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXDEPTHNAME', & ! tag name
+    'AUXDEPTHNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_boundnames = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'OPTIONS', & ! block
+    'BOUNDNAMES', & ! tag name
+    'BOUNDNAMES', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_iprpak = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_INPUT', & ! tag name
+    'IPRPAK', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_iprflow = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_FLOWS', & ! tag name
+    'IPRFLOW', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_ipakcb = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'OPTIONS', & ! block
+    'SAVE_FLOWS', & ! tag name
+    'IPAKCB', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_ts_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS_FILERECORD', & ! tag name
+    'TS_FILERECORD', & ! fortran variable
+    'RECORD TS6 FILEIN TS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_ts6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS6', & ! tag name
+    'TS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_filein = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'OPTIONS', & ! block
+    'FILEIN', & ! tag name
+    'FILEIN', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_ts6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS6_FILENAME', & ! tag name
+    'TS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_obs_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS_FILERECORD', & ! tag name
+    'OBS_FILERECORD', & ! fortran variable
+    'RECORD OBS6 FILEIN OBS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_obs6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6', & ! tag name
+    'OBS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_obs6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6_FILENAME', & ! tag name
+    'OBS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_mover = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'OPTIONS', & ! block
+    'MOVER', & ! tag name
+    'MOVER', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_icubicsfac = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'OPTIONS', & ! block
+    'DEV_CUBIC_SCALING', & ! tag name
+    'ICUBICSFAC', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_maxbound = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'DIMENSIONS', & ! block
+    'MAXBOUND', & ! tag name
+    'MAXBOUND', & ! fortran variable
+    'INTEGER', & ! type
+    '', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_cellid = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'PERIOD', & ! block
+    'CELLID', & ! tag name
+    'CELLID', & ! fortran variable
+    'INTEGER1D', & ! type
+    'NCELLDIM', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_elev = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'PERIOD', & ! block
+    'ELEV', & ! tag name
+    'ELEV', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_cond = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'PERIOD', & ! block
+    'COND', & ! tag name
+    'COND', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_auxvar = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'PERIOD', & ! block
+    'AUX', & ! tag name
+    'AUXVAR', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_boundname = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'PERIOD', & ! block
+    'BOUNDNAME', & ! tag name
+    'BOUNDNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_drn_param_definitions(*) = &
+    [ &
+    gwfdrn_auxiliary, &
+    gwfdrn_auxmultname, &
+    gwfdrn_auxdepthname, &
+    gwfdrn_boundnames, &
+    gwfdrn_iprpak, &
+    gwfdrn_iprflow, &
+    gwfdrn_ipakcb, &
+    gwfdrn_ts_filerecord, &
+    gwfdrn_ts6, &
+    gwfdrn_filein, &
+    gwfdrn_ts6_filename, &
+    gwfdrn_obs_filerecord, &
+    gwfdrn_obs6, &
+    gwfdrn_obs6_filename, &
+    gwfdrn_mover, &
+    gwfdrn_icubicsfac, &
+    gwfdrn_maxbound, &
+    gwfdrn_cellid, &
+    gwfdrn_elev, &
+    gwfdrn_cond, &
+    gwfdrn_auxvar, &
+    gwfdrn_boundname &
+    ]
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfdrn_spd = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'DRN', & ! subcomponent
+    'PERIOD', & ! block
+    'STRESS_PERIOD_DATA', & ! tag name
+    'SPD', & ! fortran variable
+    'RECARRAY CELLID ELEV COND AUX BOUNDNAME', & ! type
+    'MAXBOUND', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_drn_aggregate_definitions(*) = &
+    [ &
+    gwfdrn_spd &
+    ]
+
+  type(InputBlockDefinitionType), parameter :: &
+    gwf_drn_block_definitions(*) = &
+    [ &
+    InputBlockDefinitionType( &
+    'OPTIONS', & ! blockname
+    .false., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'DIMENSIONS', & ! blockname
+    .true., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'PERIOD', & ! blockname
+    .true., & ! required
+    .true., & ! aggregate
+    .true. & ! block_variable
+    ) &
+    ]
+
+end module GwfDrnInputModule
diff --git a/src/Model/GroundWaterFlow/gwf3evt8.f90 b/src/Model/GroundWaterFlow/gwf3evt8.f90
index 34d687cfbdf..66ce0154798 100644
--- a/src/Model/GroundWaterFlow/gwf3evt8.f90
+++ b/src/Model/GroundWaterFlow/gwf3evt8.f90
@@ -1,18 +1,18 @@
 module EvtModule
   !
-  use KindModule, only: DP, I4B
+  use KindModule, only: DP, I4B, LGP
   use ConstantsModule, only: DZERO, DONE, LENFTYPE, LENPACKAGENAME, MAXCHARLEN, &
                              IWETLAKE
   use MemoryHelperModule, only: create_mem_path
   use BndModule, only: BndType
-  use SimModule, only: store_error, store_error_unit, count_errors
+  use BndExtModule, only: BndExtType
+  use SimModule, only: store_error, store_error_filename, count_errors
   use SimVariablesModule, only: errmsg
   use ObsModule, only: DefaultObsIdProcessor
-  use TimeArraySeriesLinkModule, only: TimeArraySeriesLinkType
-  use TimeSeriesLinkModule, only: TimeSeriesLinkType, &
-                                  GetTimeSeriesLinkFromList
   use BlockParserModule, only: BlockParserType
+  use CharacterStringModule, only: CharacterStringType
   use MatrixBaseModule
+  use GeomUtilModule, only: get_node
   !
   implicit none
   !
@@ -23,21 +23,28 @@ module EvtModule
   character(len=LENPACKAGENAME) :: text = '             EVT'
   character(len=LENPACKAGENAME) :: texta = '           EVTA'
   !
-  type, extends(BndType) :: EvtType
+  type, extends(BndExtType) :: EvtType
     ! -- logicals
-    logical, private :: segsdefined = .true.
-    logical, private :: fixed_cell = .false.
-    logical, private :: read_as_arrays = .false.
-    logical, private :: surfratespecified = .false.
+    logical, pointer, private :: segsdefined
+    logical, pointer, private :: fixed_cell
+    logical, pointer, private :: read_as_arrays
+    logical, pointer, private :: surfratespecified
     ! -- integers
-    integer(I4B), pointer :: inievt => null()
-    integer(I4B), pointer, private :: nseg => null()
+    integer(I4B), pointer, private :: nseg => null() !< number of ET segments
     ! -- arrays
+    real(DP), dimension(:), pointer, contiguous :: surface => null() !< elevation of the ET surface
+    real(DP), dimension(:), pointer, contiguous :: rate => null() !< maximum ET flux rate
+    real(DP), dimension(:), pointer, contiguous :: depth => null() !< ET extinction depth
+    real(DP), dimension(:, :), pointer, contiguous :: pxdp => null() !< proportion of ET extinction depth at bottom of segment
+    real(DP), dimension(:, :), pointer, contiguous :: petm => null() !< proportion of max ET flux rate at bottom of segment
+    real(DP), dimension(:), pointer, contiguous :: petm0 => null() !< proportion of max ET flux rate that will apply when head is at or above ET surface
     integer(I4B), dimension(:), pointer, contiguous :: nodesontop => null()
   contains
     procedure :: evt_allocate_scalars
-    procedure :: bnd_options => evt_options
-    procedure :: read_dimensions => evt_read_dimensions
+    procedure :: allocate_arrays => evt_allocate_arrays
+    procedure :: source_options => evt_source_options
+    procedure :: source_dimensions => evt_source_dimensions
+    procedure :: evt_log_options
     procedure :: read_initial_attr => evt_read_initial_attr
     procedure :: bnd_rp => evt_rp
     procedure :: set_nodesontop
@@ -45,40 +52,21 @@ module EvtModule
     procedure :: bnd_fc => evt_fc
     procedure :: bnd_da => evt_da
     procedure :: define_listlabel => evt_define_listlabel
-    procedure, private :: evt_rp_array
-    procedure, private :: evt_rp_list
+    procedure :: bound_value => evt_bound_value
     procedure, private :: default_nodelist
     procedure, private :: check_pxdp
     ! -- for observations
     procedure, public :: bnd_obs_supported => evt_obs_supported
     procedure, public :: bnd_df_obs => evt_df_obs
-    ! -- for time series
-    procedure, public :: bnd_rp_ts => evt_rp_ts
   end type EvtType
 
-  ! EVT uses BndType%bound array columns:
-  ! Index                  Description                   old name  Keyword
-  !  (1,n)                 ET Surface elevation            ETSS    SURFACE
-  !  (2,n)                 Max ET Rate                     ETSR    RATE
-  !  (3,n)                 Extinction Depth                ETSX    DEPTH
-  ! Used only if nseg > 1 and surfratespecified is false:
-  !   4->2+nseg            Proportion of Extinction Depth  PXDP    PXDP
-  !   3+nseg->3+2(nseg-1)  Proportion of Max ET Rate       PETM    PETM
-  ! If nseg > 1 and surfratespecified is true:
-  !   4->3+nseg            Proportion of Extinction Depth  PXDP    PXDP
-  !   4+nseg->3+2(nseg)    Proportion of Max ET Rate       PETM    PETM
-
 contains
 
-  subroutine evt_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
-! ******************************************************************************
-! evt_create -- Create a new Evapotranspiration Segments Package
-! Subroutine: (1) create new-style package
-!             (2) point packobj to the new package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Create a new Evapotranspiration Segments Package and point pakobj
+  !! to the new package
+  !<
+  subroutine evt_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
+                        mempath)
     ! -- dummy
     class(BndType), pointer :: packobj
     integer(I4B), intent(in) :: id
@@ -87,16 +75,16 @@ subroutine evt_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     integer(I4B), intent(in) :: iout
     character(len=*), intent(in) :: namemodel
     character(len=*), intent(in) :: pakname
+    character(len=*), intent(in) :: mempath
     ! -- local
     type(EvtType), pointer :: evtobj
-! ------------------------------------------------------------------------------
     !
     ! -- allocate evt object and scalar variables
     allocate (evtobj)
     packobj => evtobj
     !
     ! -- create name and memory path
-    call packobj%set_names(ibcnum, namemodel, pakname, ftype)
+    call packobj%set_names(ibcnum, namemodel, pakname, ftype, mempath)
     packobj%text = text
     !
     ! -- allocate scalars
@@ -109,61 +97,163 @@ subroutine evt_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     packobj%iout = iout
     packobj%id = id
     packobj%ibcnum = ibcnum
-    packobj%ncolbnd = 3 ! Assumes NSEG = 1 and SURF_RATE_SPECIFIED=False
-    packobj%iscloc = 2 ! sfac applies to max. ET rate
     packobj%ictMemPath = create_mem_path(namemodel, 'NPF')
-    ! indxconvertflux is Column index of bound that will be multiplied by
-    ! cell area to convert flux rates to flow rates
-    packobj%indxconvertflux = 2
-    packobj%AllowTimeArraySeries = .true.
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine evt_create
 
+  !> @brief Allocate package scalar members
+  !<
   subroutine evt_allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars -- allocate scalar members
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
-    use MemoryManagerModule, only: mem_allocate
+    use MemoryManagerModule, only: mem_allocate, mem_setptr
     ! -- dummy
     class(EvtType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- call standard BndType allocate scalars
-    call this%BndType%allocate_scalars()
+    call this%BndExtType%allocate_scalars()
     !
     ! -- allocate the object and assign values to object variables
-    call mem_allocate(this%inievt, 'INIEVT', this%memoryPath)
     call mem_allocate(this%nseg, 'NSEG', this%memoryPath)
     !
+    ! -- allocate internal members
+    allocate (this%segsdefined)
+    allocate (this%fixed_cell)
+    allocate (this%read_as_arrays)
+    allocate (this%surfratespecified)
+    !
     ! -- Set values
-    this%inievt = 0
     this%nseg = 1
+    this%segsdefined = .true.
     this%fixed_cell = .false.
+    this%read_as_arrays = .false.
+    this%surfratespecified = .false.
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine evt_allocate_scalars
 
-  subroutine evt_options(this, option, found)
-! ******************************************************************************
-! evt_options -- set options specific to EvtType
-!   evt_options overrides BndType%bnd_options
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Allocate package arrays
+  !<
+  subroutine evt_allocate_arrays(this, nodelist, auxvar)
+    ! -- modules
+    use MemoryManagerModule, only: mem_allocate, mem_setptr, mem_checkin
+    ! -- dummy
+    class(EvtType) :: this
+    integer(I4B), dimension(:), pointer, contiguous, optional :: nodelist
+    real(DP), dimension(:, :), pointer, contiguous, optional :: auxvar
+    !
+    ! -- call standard BndType allocate scalars
+    call this%BndExtType%allocate_arrays(nodelist, auxvar)
+    !
+    ! -- set EVT input context pointers
+    call mem_setptr(this%surface, 'SURFACE', this%input_mempath)
+    call mem_setptr(this%rate, 'RATE', this%input_mempath)
+    call mem_setptr(this%depth, 'DEPTH', this%input_mempath)
+    !
+    ! -- checkin EVT input context pointers
+    call mem_checkin(this%surface, 'SURFACE', this%memoryPath, &
+                     'SURFACE', this%input_mempath)
+    call mem_checkin(this%rate, 'RATE', this%memoryPath, &
+                     'RATE', this%input_mempath)
+    call mem_checkin(this%depth, 'DEPTH', this%memoryPath, &
+                     'DEPTH', this%input_mempath)
+    !
+    ! -- set list input segment descriptors
+    if (.not. this%read_as_arrays) then
+      if (this%nseg > 1) then
+        !
+        ! -- set pxdp and petm input context pointers
+        call mem_setptr(this%pxdp, 'PXDP', this%input_mempath)
+        call mem_setptr(this%petm, 'PETM', this%input_mempath)
+        !
+        ! -- checkin pxdp and petm input context pointers
+        call mem_checkin(this%pxdp, 'PXDP', this%memoryPath, &
+                         'PXDP', this%input_mempath)
+        call mem_checkin(this%petm, 'PETM', this%memoryPath, &
+                         'PETM', this%input_mempath)
+      end if
+      !
+      if (this%surfratespecified) then
+        !
+        ! -- set petm0 input context pointer
+        call mem_setptr(this%petm0, 'PETM0', this%input_mempath)
+        !
+        ! -- cehckin petm0 input context pointer
+        call mem_checkin(this%petm0, 'PETM0', this%memoryPath, &
+                         'PETM0', this%input_mempath)
+      end if
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine evt_allocate_arrays
+
+  !> @brief Source options specific to EvtType
+  !<
+  subroutine evt_source_options(this)
+    ! -- modules
+    use MemoryManagerExtModule, only: mem_set_value
     ! -- dummy
     class(EvtType), intent(inout) :: this
-    character(len=*), intent(inout) :: option
-    logical, intent(inout) :: found
     ! -- local
-    character(len=MAXCHARLEN) :: ermsg
+    logical(LGP) :: found_fixed_cell = .false.
+    logical(LGP) :: found_readasarrays = .false.
+    logical(LGP) :: found_surfratespec = .false.
+    !
+    ! -- source common bound options
+    call this%BndExtType%source_options()
+    !
+    ! -- update defaults with idm sourced values
+    call mem_set_value(this%fixed_cell, 'FIXED_CELL', &
+                       this%input_mempath, found_fixed_cell)
+    call mem_set_value(this%read_as_arrays, 'READASARRAYS', &
+                       this%input_mempath, found_readasarrays)
+    call mem_set_value(this%surfratespecified, 'SURFRATESPEC', &
+                       this%input_mempath, found_surfratespec)
+    !
+    if (found_readasarrays) then
+      if (this%dis%supports_layers()) then
+        this%text = texta
+      else
+        errmsg = 'READASARRAYS option is not compatible with selected'// &
+                 ' discretization type.'
+        call store_error(errmsg)
+        call store_error_filename(this%input_fname)
+      end if
+    end if
+    !
+    if (found_readasarrays .and. found_surfratespec) then
+      if (this%read_as_arrays) then
+        errmsg = 'READASARRAYS option is not compatible with the'// &
+                 ' SURF_RATE_SPECIFIED option.'
+        call store_error(errmsg)
+        call store_error_filename(this%input_fname)
+      end if
+    end if
+    !
+    ! -- log evt specific options
+    call this%evt_log_options(found_fixed_cell, found_readasarrays, &
+                              found_surfratespec)
+    !
+    ! -- Return
+    return
+  end subroutine evt_source_options
+
+  !> @brief Source options specific to EvtType
+  !<
+  subroutine evt_log_options(this, found_fixed_cell, found_readasarrays, &
+                             found_surfratespec)
+    ! -- modules
+    use MemoryManagerModule, only: mem_reallocate, mem_setptr
+    use MemoryManagerExtModule, only: mem_set_value
+    use CharacterStringModule, only: CharacterStringType
+    ! -- dummy
+    class(EvtType), intent(inout) :: this
+    logical(LGP), intent(in) :: found_fixed_cell
+    logical(LGP), intent(in) :: found_readasarrays
+    logical(LGP), intent(in) :: found_surfratespec
     ! -- formats
     character(len=*), parameter :: fmtihact = &
       &"(4x, 'EVAPOTRANSPIRATION WILL BE APPLIED TO HIGHEST ACTIVE CELL.')"
@@ -175,173 +265,110 @@ subroutine evt_options(this, option, found)
       &"(4x, 'ET RATE AT SURFACE WILL BE ZERO.')"
     character(len=*), parameter :: fmtsrs = &
       &"(4x, 'ET RATE AT SURFACE WILL BE AS SPECIFIED BY PETM0.')"
-! ------------------------------------------------------------------------------
     !
-    ! -- Check for FIXED_CELL AND LAYERED
-    select case (option)
-    case ('FIXED_CELL')
-      this%fixed_cell = .true.
+    ! -- log found options
+    write (this%iout, '(/1x,a)') 'PROCESSING '//trim(adjustl(this%text)) &
+      //' OPTIONS'
+    !
+    if (found_fixed_cell) then
       write (this%iout, fmtfixedcell)
-      found = .true.
-    case ('SURF_RATE_SPECIFIED')
-      this%surfratespecified = .true.
-      write (this%iout, fmtsrs)
-      found = .true.
-      !
-      if (this%read_as_arrays) then
-        ermsg = 'READASARRAYS option is not compatible with the'// &
-                ' SURF_RATE_SPECIFIED option.'
-        call store_error(ermsg)
-        call this%parser%StoreErrorUnit()
-      end if
-    case ('READASARRAYS')
-      if (this%dis%supports_layers()) then
-        this%read_as_arrays = .true.
-        this%text = texta
-      else
-        ermsg = 'READASARRAYS option is not compatible with selected'// &
-                ' discretization type.'
-        call store_error(ermsg)
-        call this%parser%StoreErrorUnit()
-      end if
-      !
-      if (this%surfratespecified) then
-        ermsg = 'READASARRAYS option is not compatible with the'// &
-                ' SURF_RATE_SPECIFIED option.'
-        call store_error(ermsg)
-        call this%parser%StoreErrorUnit()
-      end if
-      !
-      ! -- Write option
+    end if
+    !
+    if (found_readasarrays) then
       write (this%iout, fmtreadasarrays)
-      !
-      found = .true.
-    case default
-      !
-      ! -- No options found
-      found = .false.
-    end select
+    end if
+    !
+    if (found_surfratespec) then
+      write (this%iout, fmtsrs)
+    end if
+    !
+    ! -- close logging block
+    write (this%iout, '(1x,a)') &
+      'END OF '//trim(adjustl(this%text))//' OPTIONS'
     !
-    ! -- return
+    ! -- Return
     return
-  end subroutine evt_options
+  end subroutine evt_log_options
 
-  subroutine evt_read_dimensions(this)
-! ******************************************************************************
-! bnd_read_dimensions -- Read the dimensions for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use ConstantsModule, only: LINELENGTH
-    use SimModule, only: store_error, store_error_unit
+  !> @brief Source the dimensions for this package
+  !<
+  subroutine evt_source_dimensions(this)
+    ! -- modules
+    use MemoryManagerExtModule, only: mem_set_value
     ! -- dummy
     class(EvtType), intent(inout) :: this
     ! -- local
-    character(len=LINELENGTH) :: keyword
-    integer(I4B) :: ierr
-    logical :: isfound, endOfBlock
+    logical(LGP) :: found_nseg = .false.
     ! -- format
     character(len=*), parameter :: fmtnsegerr = &
       &"('Error: In EVT, NSEG must be > 0 but is specified as ',i0)"
-! ------------------------------------------------------------------------------
     !
     ! Dimensions block is not required if:
     !   (1) discretization is DIS or DISV, and
     !   (2) READASARRAYS option has been specified.
     if (this%read_as_arrays) then
       this%maxbound = this%dis%get_ncpl()
+      !
+      ! -- verify dimensions were set
+      if (this%maxbound <= 0) then
+        write (errmsg, '(a)') &
+          'MAXBOUND must be an integer greater than zero.'
+        call store_error(errmsg)
+        call store_error_filename(this%input_fname)
+      end if
+      !
     else
-      ! -- get dimensions block
-      call this%parser%GetBlock('DIMENSIONS', isfound, ierr, &
-                                supportOpenClose=.true.)
       !
-      ! -- parse dimensions block if detected
-      if (isfound) then
-        write (this%iout, '(/1x,a)') 'PROCESSING '//trim(adjustl(this%text))// &
-          ' DIMENSIONS'
-        do
-          call this%parser%GetNextLine(endOfBlock)
-          if (endOfBlock) exit
-          call this%parser%GetStringCaps(keyword)
-          select case (keyword)
-          case ('MAXBOUND')
-            if (this%read_as_arrays) then
-              errmsg = 'When READASARRAYS option is used for the selected'// &
-                       ' discretization package, MAXBOUND may not be specified.'
-              call store_error(errmsg)
-              call this%parser%StoreErrorUnit()
-            else
-              this%maxbound = this%parser%GetInteger()
-              write (this%iout, '(4x,a,i7)') 'MAXBOUND = ', this%maxbound
-            end if
-          case ('NSEG')
-            this%nseg = this%parser%GetInteger()
-            write (this%iout, '(4x,a,i0)') 'NSEG = ', this%nseg
-            if (this%nseg < 1) then
-              write (errmsg, fmtnsegerr) this%nseg
-              call store_error(errmsg)
-              call this%parser%StoreErrorUnit()
-            elseif (this%nseg > 1) then
-              ! NSEG>1 is supported only if readasarrays is false
-              if (this%read_as_arrays) then
-                errmsg = 'In the EVT package, NSEG cannot be greater than 1'// &
-                         ' when READASARRAYS is used.'
-                call store_error(errmsg)
-                call this%parser%StoreErrorUnit()
-              end if
-              ! -- Recalculate number of columns required in bound array.
-              if (this%surfratespecified) then
-                this%ncolbnd = 4 + 2 * (this%nseg - 1)
-              else
-                this%ncolbnd = 3 + 2 * (this%nseg - 1)
-              end if
-            elseif (this%nseg == 1) then
-              ! if surf_rate_specified is true, will still read petm0
-              if (this%surfratespecified) then
-                this%ncolbnd = this%ncolbnd + 1
-              end if
-            end if
-          case default
-            write (errmsg, '(a,a)') &
-              'Unknown '//trim(this%text)//' DIMENSION: ', trim(keyword)
-            call store_error(errmsg)
-            call this%parser%StoreErrorUnit()
-          end select
-        end do
+      ! -- source maxbound
+      call this%BndExtType%source_dimensions()
+      !
+      ! -- log found options
+      write (this%iout, '(/1x,a)') 'PROCESSING '//trim(adjustl(this%text)) &
+        //' DIMENSIONS'
+      !
+      ! -- update defaults with idm sourced values
+      call mem_set_value(this%nseg, 'NSEG', this%input_mempath, found_nseg)
+      !
+      if (found_nseg) then
         !
-        write (this%iout, '(1x,a)') &
-          'END OF '//trim(adjustl(this%text))//' DIMENSIONS'
-      else
-        call store_error('Required DIMENSIONS block not found.')
-        call this%parser%StoreErrorUnit()
+        write (this%iout, '(4x,a,i0)') 'NSEG = ', this%nseg
+        !
+        if (this%nseg < 1) then
+          write (errmsg, fmtnsegerr) this%nseg
+          call store_error(errmsg)
+          call store_error_filename(this%input_fname)
+          !
+        elseif (this%nseg > 1) then
+          ! NSEG>1 is supported only if readasarrays is false
+          if (this%read_as_arrays) then
+            errmsg = 'In the EVT package, NSEG cannot be greater than 1'// &
+                     ' when READASARRAYS is used.'
+            call store_error(errmsg)
+            call store_error_filename(this%input_fname)
+          end if
+          !
+        end if
       end if
-    end if
-    !
-    ! -- verify dimensions were set
-    if (this%maxbound <= 0) then
-      write (errmsg, '(a)') &
-        'MAXBOUND must be an integer greater than zero.'
-      call store_error(errmsg)
-      call this%parser%StoreErrorUnit()
+      !
+      ! -- close logging block
+      write (this%iout, '(1x,a)') &
+        'END OF '//trim(adjustl(this%text))//' DIMENSIONS'
+      !
     end if
     !
     ! -- Call define_listlabel to construct the list label that is written
     !    when PRINT_INPUT option is used.
     call this%define_listlabel()
     !
-    ! -- return
+    ! -- Return
     return
-  end subroutine evt_read_dimensions
+  end subroutine evt_source_dimensions
 
+  !> @brief Part of allocate and read
+  !!
+  !! If READASARRAYS has been specified, assign default IEVT = 1
+  !<
   subroutine evt_read_initial_attr(this)
-! ******************************************************************************
-! evt_read_initial_attr -- Part of allocate and read
-! If READASARRAYS has been specified, assign default IEVT = 1
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(EvtType), intent(inout) :: this
     !
@@ -349,138 +376,49 @@ subroutine evt_read_initial_attr(this)
       call this%default_nodelist()
     end if
     !
+    ! -- Return
     return
   end subroutine evt_read_initial_attr
 
+  !> @brief Read and Prepare
+  !!
+  !! Read itmp and new boundaries if itmp > 0
+  !<
   subroutine evt_rp(this)
-! ******************************************************************************
-! evt_rp -- Read and Prepare
-!   Read new boundaries
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use ConstantsModule, only: LINELENGTH
-    use TdisModule, only: kper, nper
-    use SimModule, only: store_error
-    use ArrayHandlersModule, only: ifind
+    use TdisModule, only: kper
+    implicit none
     ! -- dummy
     class(EvtType), intent(inout) :: this
-    ! -- local
-    integer(I4B) :: ierr
-    integer(I4B) :: node, n
-    integer(I4B) :: inievt, inrate, insurf, indepth
-    integer(I4B) :: kpxdp, kpetm
-    logical :: isfound, supportopenclose
-    character(len=LINELENGTH) :: line, msg
-    ! -- formats
-    character(len=*), parameter :: fmtblkerr = &
-      &"('Error.  Looking for BEGIN PERIOD iper.  Found ', a, ' instead.')"
-    character(len=*), parameter :: fmtlsp = &
-      &"(1X,/1X,'REUSING ',A,'S FROM LAST STRESS PERIOD')"
-    character(len=*), parameter :: fmtnbd = &
-      "(1X,/1X,'THE NUMBER OF ACTIVE ',A,'S (',I6,&
-      &') IS GREATER THAN MAXIMUM(',I6,')')"
-! ------------------------------------------------------------------------------
-    !
-    ! -- Set ionper to the stress period number for which a new block of data
-    !    will be read.
-    if (this%inunit == 0) return
-    !
-    ! -- get stress period data
-    if (this%ionper < kper) then
-      !
-      ! -- get period block
-      supportopenclose = .not. this%read_as_arrays
-      ! When reading a list, OPEN/CLOSE is handled by list reader,
-      ! so supportOpenClose needs to be false in call the GetBlock.
-      ! When reading as arrays, set supportOpenClose as desired.
-      call this%parser%GetBlock('PERIOD', isfound, ierr, &
-                                blockRequired=.false.)
-      if (isfound) then
-        !
-        ! -- read ionper and check for increasing period numbers
-        call this%read_check_ionper()
-      else
-        !
-        ! -- PERIOD block not found
-        if (ierr < 0) then
-          ! -- End of file found; data applies for remainder of simulation.
-          this%ionper = nper + 1
-        else
-          ! -- Found invalid block
-          call this%parser%GetCurrentLine(line)
-          write (errmsg, fmtblkerr) adjustl(trim(line))
-          call store_error(errmsg)
-          call this%parser%StoreErrorUnit()
-        end if
-      end if
-    end if
     !
-    ! -- Read data if ionper == kper
-    inrate = 0
-    insurf = 0
-    indepth = 0
-    inievt = 0
-    if (this%ionper == kper) then
-      !
-      ! -- Remove all time-series links associated with this package
-      call this%TsManager%Reset(this%packName)
-      call this%TasManager%Reset(this%packName)
-      !
-      ! -- Read IEVT, SURFACE, RATE, DEPTH, PXDP, PETM, and AUX
-      !    variables, if any
-      kpetm = 0
-      kpxdp = 0
+    if (this%iper /= kper) return
+    !
+    if (this%read_as_arrays) then
       !
-      if (.not. this%read_as_arrays) then
-        ! -- Read EVT input as a list
-        call this%evt_rp_list(inrate)
-      else
-        ! -- Read Evt input as arrays
-        call this%evt_rp_array(line, inrate, insurf, indepth, &
-                               kpxdp, kpetm)
-      end if
+      ! -- update nodelist based on IRCH input
+      call nodelist_update(this%nodelist, this%nbound, this%maxbound, &
+                           this%dis, this%input_mempath)
       !
-      ! -- Ensure that all required PXDP and PETM arrays
-      !    have been defined or redefined.
-      if (this%surfratespecified) then
-        if (kpxdp == this%nseg .and. kpetm == this%nseg) then
-          this%segsdefined = .true.
-        end if
-      else
-        if (kpxdp == this%nseg - 1 .and. kpxdp == this%nseg - 1) then
-          this%segsdefined = .true.
-        end if
-      end if
-      if (.not. this%segsdefined) then
-        msg = 'Error in EVT input: Definition of PXDP or PETM is incomplete.'
-        call store_error(msg)
-        call this%parser%StoreErrorUnit()
-      end if
     else
-      write (this%iout, fmtlsp) trim(this%filtyp)
-    end if
-    !
-    ! -- If rate was read, then multiply by cell area.  If inrate = 2, then
-    !    rate is begin managed as a time series, and the time series object
-    !    will multiply the rate by the cell area.
-    if (inrate == 1) then
-      do n = 1, this%nbound
-        node = this%nodelist(n)
-        if (node > 0) then
-          this%bound(2, n) = this%bound(2, n) * this%dis%get_area(node)
-        end if
-      end do
+      !
+      ! -- process the input list arrays
+      call this%BndExtType%bnd_rp()
       !
       ! -- ensure pxdp is monotonically increasing
       if (this%nseg > 1) then
         call this%check_pxdp()
       end if
+      !
+      ! -- Write the list to iout if requested
+      if (this%iprpak /= 0) then
+        call this%write_list()
+      end if
+      !
     end if
     !
-    ! -- return
+    ! -- copy nodelist to nodesontop if not fixed cell
+    if (.not. this%fixed_cell) call this%set_nodesontop()
+    !
+    ! -- Return
     return
   end subroutine evt_rp
 
@@ -489,7 +427,6 @@ end subroutine evt_rp
   !! If the number of EVT segments (nseg) is greater than one, then
   !! pxdp must be monotically increasing from zero to one.  Check
   !! to make sure this is the case.
-  !!
   !<
   subroutine check_pxdp(this)
     ! -- dummy
@@ -518,7 +455,7 @@ subroutine check_pxdp(this)
         !
         ! -- set and check pxdp2
         if (i < this%nseg) then
-          pxdp2 = this%bound(i + 3, n)
+          pxdp2 = this%pxdp(i, n)
           if (pxdp2 <= DZERO .or. pxdp2 >= DONE) then
             call this%dis%noder_to_string(node, nodestr)
             write (errmsg, fmtpxdp0) pxdp2, trim(nodestr)
@@ -547,23 +484,17 @@ subroutine check_pxdp(this)
       call this%parser%StoreErrorUnit()
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine check_pxdp
 
+  !> @brief Store nodelist in nodesontop
+  !<
   subroutine set_nodesontop(this)
-! ******************************************************************************
-! set_nodesontop -- store nodelist in nodesontop
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(EvtType), intent(inout) :: this
     ! -- local
     integer(I4B) :: n
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- allocate if necessary
     if (.not. associated(this%nodesontop)) then
@@ -575,27 +506,21 @@ subroutine set_nodesontop(this)
       this%nodesontop(n) = this%nodelist(n)
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine set_nodesontop
 
-  subroutine evt_cf(this, reset_mover)
-! ******************************************************************************
-! evt_cf -- Formulate the HCOF and RHS terms
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Formulate the HCOF and RHS terms
+  !<
+  subroutine evt_cf(this)
     ! -- dummy
     class(EvtType) :: this
-    logical, intent(in), optional :: reset_mover
     ! -- local
     integer(I4B) :: i, iseg, node
     integer(I4B) :: idxdepth, idxrate
     real(DP) :: c, d, h, s, x
     real(DP) :: petm0
     real(DP) :: petm1, petm2, pxdp1, pxdp2, thcof, trhs
-! ------------------------------------------------------------------------------
     !
     ! -- Return if no ET nodes
     if (this%nbound == 0) return
@@ -631,11 +556,16 @@ subroutine evt_cf(this, reset_mover)
       ! -- if ibound is positive and not overlain by a lake, then add terms
       if (this%ibound(node) > 0 .and. this%ibound(node) /= IWETLAKE) then
         !
-        c = this%bound(2, i) ! RATE -- max. ET rate
-        s = this%bound(1, i) ! SURFACE -- ET surface elevation
+        if (this%iauxmultcol > 0) then
+          c = this%rate(i) * this%dis%get_area(node) * &
+              this%auxvar(this%iauxmultcol, i)
+        else
+          c = this%rate(i) * this%dis%get_area(node)
+        end if
+        s = this%surface(i)
         h = this%xnew(node)
         if (this%surfratespecified) then
-          petm0 = this%bound(4 + 2 * (this%nseg - 1), i) ! PETM0
+          petm0 = this%petm0(i)
         end if
         !
         ! -- If head in cell is greater than or equal to SURFACE, ET is constant
@@ -650,7 +580,7 @@ subroutine evt_cf(this, reset_mover)
         else
           ! -- If depth to water >= extinction depth, then ET is 0
           d = S - h
-          x = this%bound(3, i) ! DEPTH -- extinction depth
+          x = this%depth(i)
           if (d < x) then
             ! -- Variable range. add ET terms to both RHS and HCOF.
             if (this%nseg > 1) then
@@ -673,8 +603,8 @@ subroutine evt_cf(this, reset_mover)
               end if
               ! -- Initialize indices to point to elements preceding
               !    pxdp1 and petm1 (values for lower end of segment 1).
-              idxdepth = 3
-              idxrate = 2 + this%nseg
+              idxdepth = 0
+              idxrate = 0
               ! -- Iterate through segments to find segment that contains
               !    current depth of head below ET surface.
               segloop: do iseg = 1, this%nseg
@@ -685,8 +615,8 @@ subroutine evt_cf(this, reset_mover)
                   idxdepth = idxdepth + 1
                   idxrate = idxrate + 1
                   ! -- Get proportions for lower end of segment
-                  pxdp2 = this%bound(idxdepth, i)
-                  petm2 = this%bound(idxrate, i)
+                  pxdp2 = this%pxdp(idxdepth, i)
+                  petm2 = this%petm(idxrate, i)
                 else
                   pxdp2 = DONE
                   petm2 = DZERO
@@ -718,17 +648,13 @@ subroutine evt_cf(this, reset_mover)
       !
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine evt_cf
 
+  !> @brief Copy rhs and hcof into solution rhs and amat
+  !<
   subroutine evt_fc(this, rhs, ia, idxglo, matrix_sln)
-! **************************************************************************
-! evt_fc -- Copy rhs and hcof into solution rhs and amat
-! **************************************************************************
-!
-!    SPECIFICATIONS:
-! --------------------------------------------------------------------------
     ! -- dummy
     class(EvtType) :: this
     real(DP), dimension(:), intent(inout) :: rhs
@@ -737,7 +663,6 @@ subroutine evt_fc(this, rhs, ia, idxglo, matrix_sln)
     class(MatrixBaseType), pointer :: matrix_sln
     ! -- local
     integer(I4B) :: i, n, ipos
-! --------------------------------------------------------------------------
     !
     ! -- Copy package rhs and hcof into solution rhs and amat
     do i = 1, this%nbound
@@ -754,379 +679,57 @@ subroutine evt_fc(this, rhs, ia, idxglo, matrix_sln)
       call matrix_sln%add_value_pos(idxglo(ipos), this%hcof(i))
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine evt_fc
 
+  !> @brief Deallocate
+  !<
   subroutine evt_da(this)
-! ******************************************************************************
-! evt_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(EvtType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- arrays
     if (associated(this%nodesontop)) deallocate (this%nodesontop)
+    call mem_deallocate(this%surface, 'SURFACE', this%memoryPath)
+    call mem_deallocate(this%rate, 'RATE', this%memoryPath)
+    call mem_deallocate(this%depth, 'DEPTH', this%memoryPath)
+    !
+    if (.not. this%read_as_arrays) then
+      if (this%nseg > 1) then
+        call mem_deallocate(this%pxdp, 'PXDP', this%memoryPath)
+        call mem_deallocate(this%petm, 'PETM', this%memoryPath)
+      end if
+      !
+      if (this%surfratespecified) then
+        call mem_deallocate(this%petm0, 'PETM0', this%memoryPath)
+      end if
+    end if
     !
     ! -- scalars
-    call mem_deallocate(this%inievt)
     call mem_deallocate(this%nseg)
+    deallocate (this%segsdefined)
+    deallocate (this%fixed_cell)
+    deallocate (this%read_as_arrays)
+    deallocate (this%surfratespecified)
     !
     ! -- Deallocate parent package
-    call this%BndType%bnd_da()
+    call this%BndExtType%bnd_da()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine evt_da
 
-  subroutine evt_rp_array(this, line, inrate, insurf, indepth, &
-                          kpxdp, kpetm)
-! ******************************************************************************
-! evt_rp_array -- Read and Prepare EVT as arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use ConstantsModule, only: LENTIMESERIESNAME, LINELENGTH
-    use SimModule, only: store_error
-    use ArrayHandlersModule, only: ifind
-    ! -- dummy
-    class(EvtType), intent(inout) :: this
-    character(len=LINELENGTH), intent(inout) :: line
-    integer(I4B), intent(inout) :: inrate
-    integer(I4B), intent(inout) :: insurf
-    integer(I4B), intent(inout) :: indepth
-    integer(I4B), intent(inout) :: kpxdp
-    integer(I4B), intent(inout) :: kpetm
-    ! -- local
-    integer(I4B) :: n
-    integer(I4B) :: indx, ipos
-    integer(I4B) :: jcol, jauxcol, lpos, ivarsread
-    character(len=LENTIMESERIESNAME) :: tasName
-    character(len=24), dimension(6) :: aname
-    character(len=100) :: ermsg, keyword, atemp
-    logical :: found, endOfBlock
-    logical :: convertFlux
-    !
-    ! -- these time array series pointers need to be non-contiguous
-    !    beacuse a slice of bound is passed
-    real(DP), dimension(:), pointer :: bndArrayPtr => null()
-    real(DP), dimension(:), pointer :: auxArrayPtr => null()
-    real(DP), dimension(:), pointer :: auxMultArray => null()
-    type(TimeArraySeriesLinkType), pointer :: tasLink => null()
-    ! -- formats
-    character(len=*), parameter :: fmtevtauxmult = &
-      "(4x, 'THE ET RATE ARRAY IS BEING MULTIPLED BY THE AUXILIARY ARRAY WITH &
-        &THE NAME: ', A)"
-    ! -- data
-    data aname(1)/'     LAYER OR NODE INDEX'/
-    data aname(2)/'              ET SURFACE'/
-    data aname(3)/' EVAPOTRANSPIRATION RATE'/
-    data aname(4)/'        EXTINCTION DEPTH'/
-    data aname(5)/'EXTINCT. DEP. PROPORTION'/
-    data aname(6)/'      ET RATE PROPORTION'/
-! ------------------------------------------------------------------------------
-    !
-    ! -- Initialize
-    jauxcol = 0
-    ivarsread = 0
-    !
-    ! -- Read IEVT, SURFACE, RATE, DEPTH, PXDP, PETM, and AUX
-    !    as arrays
-    kpetm = 0
-    kpxdp = 0
-    do
-      call this%parser%GetNextLine(endOfBlock)
-      if (endOfBlock) exit
-      call this%parser%GetStringCaps(keyword)
-      !
-      ! -- Parse the keywords
-      select case (keyword)
-      case ('IEVT')
-        !
-        ! -- Check to see if other variables have already been read.  If so,
-        !    then terminate with an error that IEVT must be read first.
-        if (ivarsread > 0) then
-          call store_error('IEVT is not first variable in &
-            &period block or it is specified more than once.')
-          call this%parser%StoreErrorUnit()
-        end if
-        !
-        ! -- Read the IEVT array
-        call this%dis%nlarray_to_nodelist(this%nodelist, this%maxbound, &
-                                          this%nbound, aname(1), &
-                                          this%parser%iuactive, this%iout)
-        !
-        ! -- set flag to indicate that IEVT has been read
-        this%inievt = 1
-        !
-        ! -- if highest_active option set, then need to store nodelist
-        !    in the nodesontop array
-        if (.not. this%fixed_cell) call this%set_nodesontop()
-        !
-      case ('SURFACE')
-        !
-        if (this%inievt == 0) then
-          call store_error('IEVT must be read at least once &
-            &prior to reading the SURFACE array.')
-          call this%parser%StoreErrorUnit()
-        end if
-        !
-        ! -- Read the surface array, then indicate
-        !    that surface array was read by setting insurf
-        call this%dis%read_layer_array(this%nodelist, this%bound, this%ncolbnd, &
-                                       this%maxbound, 1, aname(2), &
-                                       this%parser%iuactive, this%iout)
-        insurf = 1
-        !
-      case ('RATE')
-        !
-        ! -- Look for keyword TIMEARRAYSERIES and time-array series
-        !    name on line, following RATE
-        call this%parser%GetStringCaps(keyword)
-        if (keyword == 'TIMEARRAYSERIES') then
-          ! -- Get time-array series name
-          call this%parser%GetStringCaps(tasName)
-          ! -- Ensure that time-array series has been defined and that name
-          !    of time-array series is valid.
-          jcol = 2 ! for max ET rate
-          bndArrayPtr => this%bound(jcol, :)
-          ! Make a time-array-series link and add it to the list of links
-          ! contained in the TimeArraySeriesManagerType object.
-          convertflux = .true.
-          call this%TasManager%MakeTasLink(this%packName, bndArrayPtr, &
-                                           this%iprpak, tasName, 'RATE', &
-                                           convertFlux, this%nodelist, &
-                                           this%parser%iuactive)
-          lpos = this%TasManager%CountLinks()
-          tasLink => this%TasManager%GetLink(lpos)
-          inrate = 2
-        else
-          !
-          ! -- Read the Max. ET Rate array, then indicate
-          !    that rate array was read by setting inrate
-          call this%dis%read_layer_array(this%nodelist, this%bound, &
-                                         this%ncolbnd, this%maxbound, 2, &
-                                         aname(3), this%parser%iuactive, &
-                                         this%iout)
-          inrate = 1
-        end if
-        !
-      case ('DEPTH')
-        !
-        if (this%inievt == 0) then
-          call store_error('IEVT must be read at least once &
-                           &prior to reading the DEPTH array.')
-          call this%parser%StoreErrorUnit()
-        end if
-        !
-        ! -- Read the extinction-depth array, then indicate
-        !    that depth array was read by setting indepth
-        call this%dis%read_layer_array(this%nodelist, this%bound, this%ncolbnd, &
-                                       this%maxbound, 3, aname(4), &
-                                       this%parser%iuactive, this%iout)
-        indepth = 1
-        !
-      case ('PXDP')
-        if (this%nseg < 2) then
-          ermsg = 'EVT input: PXDP cannot be specified when NSEG < 2'
-          call store_error(ermsg)
-          call this%parser%StoreErrorUnit()
-        end if
-        !
-        if (this%inievt == 0) then
-          call store_error('IEVT must be read at least once &
-                           &prior to reading any PXDP array.')
-          call this%parser%StoreErrorUnit()
-        end if
-        !
-        ! -- Assign column for this PXDP vector in bound array
-        kpxdp = kpxdp + 1
-        if (kpxdp < this%nseg - 1) this%segsdefined = .false.
-        if (kpxdp > this%nseg - 1) then
-          ermsg = 'EVT: Number of PXDP arrays exceeds NSEG-1.'
-          call store_error(ermsg)
-          call this%parser%StoreErrorUnit()
-        end if
-        indx = 3 + kpxdp
-        !
-        ! -- Read the PXDP array
-        call this%dis%read_layer_array(this%nodelist, this%bound, this%ncolbnd, &
-                                       this%maxbound, indx, aname(5), &
-                                       this%parser%iuactive, this%iout)
-        !
-      case ('PETM')
-        if (this%nseg < 2) then
-          ermsg = 'EVT input: PETM cannot be specified when NSEG < 2'
-          call store_error(ermsg)
-          call this%parser%StoreErrorUnit()
-        end if
-        !
-        if (this%inievt == 0) then
-          call store_error('IEVT must be read at least once &
-                           &prior to reading any PETM array.')
-          call this%parser%StoreErrorUnit()
-        end if
-        !
-        ! -- Assign column for this PETM vector in bound array
-        kpetm = kpetm + 1
-        if (kpetm < this%nseg - 1) this%segsdefined = .false.
-        if (kpetm > this%nseg - 1) then
-          ermsg = 'EVT: Number of PETM arrays exceeds NSEG-1.'
-          call store_error(ermsg)
-          call this%parser%StoreErrorUnit()
-        end if
-        indx = 3 + this%nseg - 1 + kpetm
-        !
-        ! -- Read the PETM array
-        call this%dis%read_layer_array(this%nodelist, this%bound, this%ncolbnd, &
-                                       this%maxbound, indx, aname(6), &
-                                       this%parser%iuactive, this%iout)
-        !
-      case default
-        !
-        ! -- Check for auxname, and if found, then read into auxvar array
-        found = .false.
-        ipos = ifind(this%auxname, keyword)
-        if (ipos > 0) then
-          found = .true.
-          atemp = keyword
-          !
-          ! -- Look for keyword TIMEARRAYSERIES and time-array series
-          !    name on line, following auxname
-          call this%parser%GetStringCaps(keyword)
-          if (keyword == 'TIMEARRAYSERIES') then
-            ! -- Get time-array series name
-            call this%parser%GetStringCaps(tasName)
-            jauxcol = jauxcol + 1
-            auxArrayPtr => this%auxvar(jauxcol, :)
-            ! Make a time-array-series link and add it to the list of links
-            ! contained in the TimeArraySeriesManagerType object.
-            convertflux = .false.
-            call this%TasManager%MakeTasLink(this%packName, auxArrayPtr, &
-                                             this%iprpak, tasName, &
-                                             this%auxname(ipos), convertFlux, &
-                                             this%nodelist, this%parser%iuactive)
-          else
-            !
-            ! -- Read the aux variable array
-            call this%dis%read_layer_array(this%nodelist, this%auxvar, &
-                                           this%naux, this%maxbound, ipos, &
-                                           atemp, this%parser%iuactive, &
-                                           this%iout)
-          end if
-        end if
-        !
-        ! -- Nothing found
-        if (.not. found) then
-          call this%parser%GetCurrentLine(line)
-          call store_error('Looking for valid variable name.  Found: ')
-          call store_error(trim(line))
-          call this%parser%StoreErrorUnit()
-        end if
-        !
-        ! If this aux variable has been designated as a multiplier array
-        ! by presence of AUXMULTNAME, set local pointer appropriately.
-        if (this%iauxmultcol > 0 .and. this%iauxmultcol == ipos) then
-          auxMultArray => this%auxvar(this%iauxmultcol, :)
-        end if
-      end select
-      !
-      ! -- Increment the number of variables read
-      ivarsread = ivarsread + 1
-      !
-    end do
-    !
-    ! -- Ensure that all required PXDP and PETM arrays
-    !    have been defined or redefined.
-    if (kpxdp == this%nseg - 1 .and. kpxdp == this%nseg - 1) then
-      this%segsdefined = .true.
-    end if
-    if (.not. this%segsdefined) then
-      ermsg = 'EVT input: Definition of PXDP or PETM is incomplete.'
-      call store_error(ermsg)
-      call this%parser%StoreErrorUnit()
-    end if
-    !
-    ! If the multiplier-array pointer has been assigned and
-    ! stress is controlled by a time-array series, assign
-    ! multiplier-array pointer in time-array series link.
-    if (associated(auxMultArray)) then
-      if (associated(tasLink)) then
-        tasLink%RMultArray => auxMultArray
-      end if
-    end if
-    !
-    ! -- If et rate was read and auxmultcol was specified, then multiply
-    !    the et rate by the multplier column
-    if (inrate == 1 .and. this%iauxmultcol > 0) then
-      write (this%iout, fmtevtauxmult) this%auxname(this%iauxmultcol)
-      do n = 1, this%nbound
-        this%bound(this%iscloc, n) = this%bound(this%iscloc, n) * &
-                                     this%auxvar(this%iauxmultcol, n)
-      end do
-    end if
-    !
-    return
-  end subroutine evt_rp_array
-
-  subroutine evt_rp_list(this, inrate)
-! ******************************************************************************
-! evt_rp_list -- Read and Prepare EVT as a list
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Define the list heading that is written to iout when PRINT_INPUT
+  !! option is used
+  !<
+  subroutine evt_define_listlabel(this)
     ! -- dummy
     class(EvtType), intent(inout) :: this
-    integer(I4B), intent(inout) :: inrate
     ! -- local
-    integer(I4B) :: maxboundorig, nlist
-! ------------------------------------------------------------------------------
-    !
-    nlist = -1
-    maxboundorig = this%maxbound
-    call this%dis%read_list(this%parser%iuactive, this%iout, this%iprpak, &
-                            nlist, this%inamedbound, this%iauxmultcol, &
-                            this%nodelist, this%bound, this%auxvar, &
-                            this%auxname, this%boundname, this%listlabel, &
-                            this%packName, this%tsManager, this%iscloc, &
-                            this%indxconvertflux)
-    this%nbound = nlist
-    if (this%maxbound > maxboundorig) then
-      ! -- The arrays that belong to BndType have been extended.
-      ! Now, EVT array nodesontop needs to be recreated.
-      if (associated(this%nodesontop)) then
-        deallocate (this%nodesontop)
-      end if
-    end if
-    if (.not. this%fixed_cell) call this%set_nodesontop()
-    inrate = 1
-    !
-    ! -- terminate the period block
-    call this%parser%terminateblock()
-    !
-    return
-  end subroutine evt_rp_list
-
-  subroutine evt_define_listlabel(this)
-! ******************************************************************************
-! define_listlabel -- Define the list heading that is written to iout when
-!   PRINT_INPUT option is used.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    class(EvtType), intent(inout) :: this
     integer(I4B) :: nsegm1, i
-! ------------------------------------------------------------------------------
     !
     ! -- create the header list label
     this%listlabel = trim(this%filtyp)//' NO.'
@@ -1169,27 +772,22 @@ subroutine evt_define_listlabel(this)
       write (this%listlabel, '(a, a16)') trim(this%listlabel), 'BOUNDARY NAME'
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine evt_define_listlabel
 
+  !> @brief Assign default nodelist when READASARRAYS is specified.
+  !!
+  !! Equivalent to reading IEVT as CONSTANT 1
+  !<
   subroutine default_nodelist(this)
-! ******************************************************************************
-! default_nodelist -- Assign default nodelist when READASARRAYS is specified.
-!                     Equivalent to reading IEVT as CONSTANT 1
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
-    use InputOutputModule, only: get_node
     use SimModule, only: store_error
     use ConstantsModule, only: LINELENGTH
     ! -- dummy
     class(EvtType) :: this
     ! -- local
     integer(I4B) :: il, ir, ic, ncol, nrow, nlay, nodeu, noder, ipos
-! ------------------------------------------------------------------------------
     !
     ! -- set variables
     if (this%dis%ndim == 3) then
@@ -1214,95 +812,159 @@ subroutine default_nodelist(this)
       end do
     end do
     !
-    ! Set flag that indicates IEVT has been assigned, and assign nbound.
-    this%inievt = 1
+    ! -- assign nbound.
     this%nbound = ipos - 1
     !
     ! -- if fixed_cell option not set, then need to store nodelist
     !    in the nodesontop array
     if (.not. this%fixed_cell) call this%set_nodesontop()
     !
-    ! -- return
+    ! -- Return
+    return
   end subroutine default_nodelist
 
   ! -- Procedures related to observations
 
+  !> @brief Return true because EVT package supports observations
+  !!
+  !! Overrides BndType%bnd_obs_supported()
+  !<
   logical function evt_obs_supported(this)
-! ******************************************************************************
-! evt_obs_supported
-!   -- Return true because EVT package supports observations.
-!   -- Overrides BndType%bnd_obs_supported()
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(EvtType) :: this
-! ------------------------------------------------------------------------------
+    !
     evt_obs_supported = .true.
     !
-    ! -- return
+    ! -- Return
     return
   end function evt_obs_supported
 
+  !> @brief Store observation type supported by EVT package
+  !!
+  !! Overrides BndType%bnd_df_obs
+  !<
   subroutine evt_df_obs(this)
-! ******************************************************************************
-! evt_df_obs (implements bnd_df_obs)
-!   -- Store observation type supported by EVT package.
-!   -- Overrides BndType%bnd_df_obs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(EvtType) :: this
     ! -- local
     integer(I4B) :: indx
-! ------------------------------------------------------------------------------
+    !
     call this%obs%StoreObsType('evt', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => DefaultObsIdProcessor
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine evt_df_obs
 
-  ! -- Procedure related to time series
+  !> @brief Return requested boundary value
+  !<
+  function evt_bound_value(this, col, row) result(bndval)
+    ! -- modules
+    use ConstantsModule, only: DZERO
+    ! -- dummy variables
+    class(EvtType), intent(inout) :: this !< BndExtType object
+    integer(I4B), intent(in) :: col
+    integer(I4B), intent(in) :: row
+    ! -- result
+    real(DP) :: bndval
+    ! -- local
+    integer(I4B) :: idx
+    !
+    ! -- initialize
+    idx = 0
+    !
+    select case (col)
+    case (1)
+      bndval = this%surface(row)
+    case (2)
+      if (this%iauxmultcol > 0) then
+        bndval = this%rate(row) * this%auxvar(this%iauxmultcol, row)
+      else
+        bndval = this%rate(row)
+      end if
+    case (3)
+      bndval = this%depth(row)
+    case default
+      if (col > 0) then
+        if (this%nseg > 1) then
+          if (col < (3 + this%nseg)) then
+            idx = col - 3
+            bndval = this%pxdp(idx, row)
+          else if (col < (3 + (2 * this%nseg) - 1)) then
+            idx = col - (3 + this%nseg - 1)
+            bndval = this%petm(idx, row)
+          else if (col == (3 + (2 * this%nseg) - 1)) then
+            if (this%surfratespecified) then
+              idx = 1
+              bndval = this%petm0(row)
+            end if
+          end if
+        else if (this%surfratespecified) then
+          if (col == 4) then
+            idx = 1
+            bndval = this%petm0(row)
+          end if
+        end if
+      end if
+      !
+      ! -- set error if idx not found
+      if (idx == 0) then
+        write (errmsg, '(a,i0,a)') &
+          'Programming error. EVT bound value requested column '&
+          &'outside range of ncolbnd (', this%ncolbnd, ').'
+        call store_error(errmsg)
+        call store_error_filename(this%input_fname)
+      end if
+      !
+    end select
+    !
+    ! -- Return
+    return
+  end function evt_bound_value
 
-  subroutine evt_rp_ts(this)
-! ******************************************************************************
-! evt_rp_ts -- Assign tsLink%Text appropriately for
-!    all time series in use by package.
-!    In EVT package the SURFACE, RATE, DEPTH, PXDP, and PETM variables
-!    can be controlled by time series.
-!    Define Text only when time series is used for SURFACE, RATE, or DEPTH.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Update the nodelist based on IEVT input
+  !!
+  !! This is a module scoped routine to check for IEVT input. If array input
+  !! was provided, INIEVT and IEVT will be allocated in the input context.
+  !! If the read state variable INIEVT is set to 1 during this period update,
+  !! IEVT input was read and is used here to update the nodelist.
+  !<
+  subroutine nodelist_update(nodelist, nbound, maxbound, &
+                             dis, input_mempath)
+    ! -- modules
+    use MemoryManagerModule, only: mem_setptr
+    use BaseDisModule, only: DisBaseType
     ! -- dummy
-    class(EvtType), intent(inout) :: this
+    integer(I4B), dimension(:), contiguous, &
+      pointer, intent(inout) :: nodelist
+    class(DisBaseType), pointer, intent(in) :: dis
+    character(len=*), intent(in) :: input_mempath
+    integer(I4B), intent(inout) :: nbound
+    integer(I4B), intent(in) :: maxbound
+    ! -- format
+    character(len=24) :: aname = '     LAYER OR NODE INDEX'
     ! -- local
-    integer(I4B) :: i, nlinks
-    type(TimeSeriesLinkType), pointer :: tslink => null()
-! ------------------------------------------------------------------------------
-    !
-    nlinks = this%TsManager%boundtslinks%Count()
-    do i = 1, nlinks
-      tslink => GetTimeSeriesLinkFromList(this%TsManager%boundtslinks, i)
-      if (associated(tslink)) then
-        select case (tslink%JCol)
-        case (1)
-          tslink%Text = 'SURFACE'
-        case (2)
-          tslink%Text = 'RATE'
-        case (3)
-          tslink%Text = 'DEPTH'
-        end select
-      end if
-    end do
+    integer(I4B), dimension(:), contiguous, pointer :: ievt => null()
+    integer(I4B), pointer :: inievt => NULL()
+    !
+    ! -- set pointer to input context INIEVT
+    call mem_setptr(inievt, 'INIEVT', input_mempath)
+    !
+    ! -- check INIEVT read state
+    if (inievt == 1) then
+      ! -- ievt was read this period
+      !
+      ! -- set pointer to input context IEVT
+      call mem_setptr(ievt, 'IEVT', input_mempath)
+      !
+      ! -- update nodelist
+      call dis%nlarray_to_nodelist(ievt, nodelist, &
+                                   maxbound, nbound, aname)
+    end if
     !
+    ! -- Return
     return
-  end subroutine evt_rp_ts
+  end subroutine nodelist_update
 
 end module EvtModule
 
diff --git a/src/Model/GroundWaterFlow/gwf3evt8idm.f90 b/src/Model/GroundWaterFlow/gwf3evt8idm.f90
new file mode 100644
index 00000000000..9ed6fe5ba12
--- /dev/null
+++ b/src/Model/GroundWaterFlow/gwf3evt8idm.f90
@@ -0,0 +1,563 @@
+! ** Do Not Modify! MODFLOW 6 system generated file. **
+module GwfEvtInputModule
+  use ConstantsModule, only: LENVARNAME
+  use InputDefinitionModule, only: InputParamDefinitionType, &
+                                   InputBlockDefinitionType
+  private
+  public gwf_evt_param_definitions
+  public gwf_evt_aggregate_definitions
+  public gwf_evt_block_definitions
+  public GwfEvtParamFoundType
+  public gwf_evt_multi_package
+
+  type GwfEvtParamFoundType
+    logical :: fixed_cell = .false.
+    logical :: auxiliary = .false.
+    logical :: auxmultname = .false.
+    logical :: boundnames = .false.
+    logical :: iprpak = .false.
+    logical :: iprflow = .false.
+    logical :: ipakcb = .false.
+    logical :: ts_filerecord = .false.
+    logical :: ts6 = .false.
+    logical :: filein = .false.
+    logical :: ts6_filename = .false.
+    logical :: obs_filerecord = .false.
+    logical :: obs6 = .false.
+    logical :: obs6_filename = .false.
+    logical :: surfratespec = .false.
+    logical :: maxbound = .false.
+    logical :: nseg = .false.
+    logical :: cellid = .false.
+    logical :: surface = .false.
+    logical :: rate = .false.
+    logical :: depth = .false.
+    logical :: pxdp = .false.
+    logical :: petm = .false.
+    logical :: petm0 = .false.
+    logical :: auxvar = .false.
+    logical :: boundname = .false.
+  end type GwfEvtParamFoundType
+
+  logical :: gwf_evt_multi_package = .true.
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_fixed_cell = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'OPTIONS', & ! block
+    'FIXED_CELL', & ! tag name
+    'FIXED_CELL', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_auxiliary = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXILIARY', & ! tag name
+    'AUXILIARY', & ! fortran variable
+    'STRING', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_auxmultname = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXMULTNAME', & ! tag name
+    'AUXMULTNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_boundnames = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'OPTIONS', & ! block
+    'BOUNDNAMES', & ! tag name
+    'BOUNDNAMES', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_iprpak = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_INPUT', & ! tag name
+    'IPRPAK', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_iprflow = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_FLOWS', & ! tag name
+    'IPRFLOW', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_ipakcb = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'OPTIONS', & ! block
+    'SAVE_FLOWS', & ! tag name
+    'IPAKCB', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_ts_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS_FILERECORD', & ! tag name
+    'TS_FILERECORD', & ! fortran variable
+    'RECORD TS6 FILEIN TS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_ts6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS6', & ! tag name
+    'TS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_filein = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'OPTIONS', & ! block
+    'FILEIN', & ! tag name
+    'FILEIN', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_ts6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS6_FILENAME', & ! tag name
+    'TS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_obs_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS_FILERECORD', & ! tag name
+    'OBS_FILERECORD', & ! fortran variable
+    'RECORD OBS6 FILEIN OBS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_obs6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6', & ! tag name
+    'OBS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_obs6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6_FILENAME', & ! tag name
+    'OBS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_surfratespec = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'OPTIONS', & ! block
+    'SURF_RATE_SPECIFIED', & ! tag name
+    'SURFRATESPEC', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_maxbound = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'DIMENSIONS', & ! block
+    'MAXBOUND', & ! tag name
+    'MAXBOUND', & ! fortran variable
+    'INTEGER', & ! type
+    '', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_nseg = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'DIMENSIONS', & ! block
+    'NSEG', & ! tag name
+    'NSEG', & ! fortran variable
+    'INTEGER', & ! type
+    '', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_cellid = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'PERIOD', & ! block
+    'CELLID', & ! tag name
+    'CELLID', & ! fortran variable
+    'INTEGER1D', & ! type
+    'NCELLDIM', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_surface = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'PERIOD', & ! block
+    'SURFACE', & ! tag name
+    'SURFACE', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_rate = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'PERIOD', & ! block
+    'RATE', & ! tag name
+    'RATE', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_depth = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'PERIOD', & ! block
+    'DEPTH', & ! tag name
+    'DEPTH', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_pxdp = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'PERIOD', & ! block
+    'PXDP', & ! tag name
+    'PXDP', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NSEG-1', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_petm = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'PERIOD', & ! block
+    'PETM', & ! tag name
+    'PETM', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NSEG-1', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_petm0 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'PERIOD', & ! block
+    'PETM0', & ! tag name
+    'PETM0', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_auxvar = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'PERIOD', & ! block
+    'AUX', & ! tag name
+    'AUXVAR', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_boundname = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'PERIOD', & ! block
+    'BOUNDNAME', & ! tag name
+    'BOUNDNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_evt_param_definitions(*) = &
+    [ &
+    gwfevt_fixed_cell, &
+    gwfevt_auxiliary, &
+    gwfevt_auxmultname, &
+    gwfevt_boundnames, &
+    gwfevt_iprpak, &
+    gwfevt_iprflow, &
+    gwfevt_ipakcb, &
+    gwfevt_ts_filerecord, &
+    gwfevt_ts6, &
+    gwfevt_filein, &
+    gwfevt_ts6_filename, &
+    gwfevt_obs_filerecord, &
+    gwfevt_obs6, &
+    gwfevt_obs6_filename, &
+    gwfevt_surfratespec, &
+    gwfevt_maxbound, &
+    gwfevt_nseg, &
+    gwfevt_cellid, &
+    gwfevt_surface, &
+    gwfevt_rate, &
+    gwfevt_depth, &
+    gwfevt_pxdp, &
+    gwfevt_petm, &
+    gwfevt_petm0, &
+    gwfevt_auxvar, &
+    gwfevt_boundname &
+    ]
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevt_spd = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVT', & ! subcomponent
+    'PERIOD', & ! block
+    'STRESS_PERIOD_DATA', & ! tag name
+    'SPD', & ! fortran variable
+    'RECARRAY CELLID SURFACE RATE DEPTH PXDP PETM PETM0 AUX BOUNDNAME', & ! type
+    'MAXBOUND', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_evt_aggregate_definitions(*) = &
+    [ &
+    gwfevt_spd &
+    ]
+
+  type(InputBlockDefinitionType), parameter :: &
+    gwf_evt_block_definitions(*) = &
+    [ &
+    InputBlockDefinitionType( &
+    'OPTIONS', & ! blockname
+    .false., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'DIMENSIONS', & ! blockname
+    .true., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'PERIOD', & ! blockname
+    .true., & ! required
+    .true., & ! aggregate
+    .true. & ! block_variable
+    ) &
+    ]
+
+end module GwfEvtInputModule
diff --git a/src/Model/GroundWaterFlow/gwf3evta8idm.f90 b/src/Model/GroundWaterFlow/gwf3evta8idm.f90
new file mode 100644
index 00000000000..a5f9a6ea56d
--- /dev/null
+++ b/src/Model/GroundWaterFlow/gwf3evta8idm.f90
@@ -0,0 +1,421 @@
+! ** Do Not Modify! MODFLOW 6 system generated file. **
+module GwfEvtaInputModule
+  use ConstantsModule, only: LENVARNAME
+  use InputDefinitionModule, only: InputParamDefinitionType, &
+                                   InputBlockDefinitionType
+  private
+  public gwf_evta_param_definitions
+  public gwf_evta_aggregate_definitions
+  public gwf_evta_block_definitions
+  public GwfEvtaParamFoundType
+  public gwf_evta_multi_package
+
+  type GwfEvtaParamFoundType
+    logical :: readasarrays = .false.
+    logical :: fixed_cell = .false.
+    logical :: auxiliary = .false.
+    logical :: auxmultname = .false.
+    logical :: iprpak = .false.
+    logical :: iprflow = .false.
+    logical :: ipakcb = .false.
+    logical :: tas_filerecord = .false.
+    logical :: tas6 = .false.
+    logical :: filein = .false.
+    logical :: tas6_filename = .false.
+    logical :: obs_filerecord = .false.
+    logical :: obs6 = .false.
+    logical :: obs6_filename = .false.
+    logical :: ievt = .false.
+    logical :: surface = .false.
+    logical :: rate = .false.
+    logical :: depth = .false.
+    logical :: auxvar = .false.
+  end type GwfEvtaParamFoundType
+
+  logical :: gwf_evta_multi_package = .true.
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_readasarrays = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'OPTIONS', & ! block
+    'READASARRAYS', & ! tag name
+    'READASARRAYS', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_fixed_cell = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'OPTIONS', & ! block
+    'FIXED_CELL', & ! tag name
+    'FIXED_CELL', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_auxiliary = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXILIARY', & ! tag name
+    'AUXILIARY', & ! fortran variable
+    'STRING', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_auxmultname = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXMULTNAME', & ! tag name
+    'AUXMULTNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_iprpak = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_INPUT', & ! tag name
+    'IPRPAK', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_iprflow = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_FLOWS', & ! tag name
+    'IPRFLOW', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_ipakcb = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'OPTIONS', & ! block
+    'SAVE_FLOWS', & ! tag name
+    'IPAKCB', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_tas_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'OPTIONS', & ! block
+    'TAS_FILERECORD', & ! tag name
+    'TAS_FILERECORD', & ! fortran variable
+    'RECORD TAS6 FILEIN TAS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_tas6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'OPTIONS', & ! block
+    'TAS6', & ! tag name
+    'TAS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_filein = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'OPTIONS', & ! block
+    'FILEIN', & ! tag name
+    'FILEIN', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_tas6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'OPTIONS', & ! block
+    'TAS6_FILENAME', & ! tag name
+    'TAS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_obs_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS_FILERECORD', & ! tag name
+    'OBS_FILERECORD', & ! fortran variable
+    'RECORD OBS6 FILEIN OBS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_obs6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6', & ! tag name
+    'OBS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_obs6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6_FILENAME', & ! tag name
+    'OBS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_ievt = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'PERIOD', & ! block
+    'IEVT', & ! tag name
+    'IEVT', & ! fortran variable
+    'INTEGER1D', & ! type
+    'NCPL', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_surface = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'PERIOD', & ! block
+    'SURFACE', & ! tag name
+    'SURFACE', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NCPL', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_rate = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'PERIOD', & ! block
+    'RATE', & ! tag name
+    'RATE', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NCPL', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_depth = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'PERIOD', & ! block
+    'DEPTH', & ! tag name
+    'DEPTH', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NCPL', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfevta_auxvar = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'EVTA', & ! subcomponent
+    'PERIOD', & ! block
+    'AUX', & ! tag name
+    'AUXVAR', & ! fortran variable
+    'DOUBLE2D', & ! type
+    'NAUX NCPL', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_evta_param_definitions(*) = &
+    [ &
+    gwfevta_readasarrays, &
+    gwfevta_fixed_cell, &
+    gwfevta_auxiliary, &
+    gwfevta_auxmultname, &
+    gwfevta_iprpak, &
+    gwfevta_iprflow, &
+    gwfevta_ipakcb, &
+    gwfevta_tas_filerecord, &
+    gwfevta_tas6, &
+    gwfevta_filein, &
+    gwfevta_tas6_filename, &
+    gwfevta_obs_filerecord, &
+    gwfevta_obs6, &
+    gwfevta_obs6_filename, &
+    gwfevta_ievt, &
+    gwfevta_surface, &
+    gwfevta_rate, &
+    gwfevta_depth, &
+    gwfevta_auxvar &
+    ]
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_evta_aggregate_definitions(*) = &
+    [ &
+    InputParamDefinitionType &
+    ( &
+    '', & ! component
+    '', & ! subcomponent
+    '', & ! block
+    '', & ! tag name
+    '', & ! fortran variable
+    '', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    ) &
+    ]
+
+  type(InputBlockDefinitionType), parameter :: &
+    gwf_evta_block_definitions(*) = &
+    [ &
+    InputBlockDefinitionType( &
+    'OPTIONS', & ! blockname
+    .true., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'PERIOD', & ! blockname
+    .true., & ! required
+    .false., & ! aggregate
+    .true. & ! block_variable
+    ) &
+    ]
+
+end module GwfEvtaInputModule
diff --git a/src/Model/GroundWaterFlow/gwf3ghb8.f90 b/src/Model/GroundWaterFlow/gwf3ghb8.f90
index d3b2b956164..f4f4cc3dda2 100644
--- a/src/Model/GroundWaterFlow/gwf3ghb8.f90
+++ b/src/Model/GroundWaterFlow/gwf3ghb8.f90
@@ -1,11 +1,12 @@
 module ghbmodule
   use KindModule, only: DP, I4B
   use ConstantsModule, only: DZERO, LENFTYPE, LENPACKAGENAME
+  use SimVariablesModule, only: errmsg
+  use SimModule, only: count_errors, store_error, store_error_filename
   use MemoryHelperModule, only: create_mem_path
   use BndModule, only: BndType
+  use BndExtModule, only: BndExtType
   use ObsModule, only: DefaultObsIdProcessor
-  use TimeSeriesLinkModule, only: TimeSeriesLinkType, &
-                                  GetTimeSeriesLinkFromList
   use MatrixBaseModule
   !
   implicit none
@@ -17,31 +18,33 @@ module ghbmodule
   character(len=LENFTYPE) :: ftype = 'GHB'
   character(len=LENPACKAGENAME) :: text = '             GHB'
   !
-  type, extends(BndType) :: GhbType
+  type, extends(BndExtType) :: GhbType
+    real(DP), dimension(:), pointer, contiguous :: bhead => null() !< GHB boundary head
+    real(DP), dimension(:), pointer, contiguous :: cond => null() !< GHB hydraulic conductance
   contains
-    procedure :: bnd_options => ghb_options
+    procedure :: allocate_arrays => ghb_allocate_arrays
+    procedure :: source_options => ghb_options
+    procedure :: log_ghb_options
+    procedure :: bnd_rp => ghb_rp
     procedure :: bnd_ck => ghb_ck
     procedure :: bnd_cf => ghb_cf
     procedure :: bnd_fc => ghb_fc
+    procedure :: bnd_da => ghb_da
     procedure :: define_listlabel
+    procedure :: bound_value => ghb_bound_value
+    procedure :: cond_mult
     ! -- methods for observations
     procedure, public :: bnd_obs_supported => ghb_obs_supported
     procedure, public :: bnd_df_obs => ghb_df_obs
-    ! -- method for time series
-    procedure, public :: bnd_rp_ts => ghb_rp_ts
+    procedure, public :: ghb_store_user_cond
   end type GhbType
 
 contains
 
-  subroutine ghb_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
-! ******************************************************************************
-! ghb_create -- Create a New Ghb Package
-! Subroutine: (1) create new-style package
-!             (2) point bndobj to the new package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Create a New Ghb Package and point bndobj to the new package
+  !<
+  subroutine ghb_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
+                        mempath)
     ! -- dummy
     class(BndType), pointer :: packobj
     integer(I4B), intent(in) :: id
@@ -50,16 +53,16 @@ subroutine ghb_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     integer(I4B), intent(in) :: iout
     character(len=*), intent(in) :: namemodel
     character(len=*), intent(in) :: pakname
+    character(len=*), intent(in) :: mempath
     ! -- local
     type(GhbType), pointer :: ghbobj
-! ------------------------------------------------------------------------------
     !
     ! -- allocate the object and assign values to object variables
     allocate (ghbobj)
     packobj => ghbobj
     !
     ! -- create name and memory path
-    call packobj%set_names(ibcnum, namemodel, pakname, ftype)
+    call packobj%set_names(ibcnum, namemodel, pakname, ftype, mempath)
     packobj%text = text
     !
     ! -- allocate scalars
@@ -72,51 +75,138 @@ subroutine ghb_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     packobj%iout = iout
     packobj%id = id
     packobj%ibcnum = ibcnum
-    packobj%ncolbnd = 2
-    packobj%iscloc = 2
     packobj%ictMemPath = create_mem_path(namemodel, 'NPF')
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine ghb_create
 
-  subroutine ghb_options(this, option, found)
-! ******************************************************************************
-! ghb_options -- set options specific to GhbType
-!
-! ghb_options overrides BndType%bnd_options
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Deallocate memory
+  !<
+  subroutine ghb_da(this)
+    ! -- modules
+    use MemoryManagerModule, only: mem_deallocate
+    ! -- dummy
+    class(GhbType) :: this
+    !
+    ! -- Deallocate parent package
+    call this%BndExtType%bnd_da()
+    !
+    ! -- arrays
+    call mem_deallocate(this%bhead, 'BHEAD', this%memoryPath)
+    call mem_deallocate(this%cond, 'COND', this%memoryPath)
+    !
+    ! -- Return
+    return
+  end subroutine ghb_da
+
+  !> @brief Set options specific to GhbType
+  !<
+  subroutine ghb_options(this)
+    ! -- modules
+    use MemoryManagerExtModule, only: mem_set_value
+    use CharacterStringModule, only: CharacterStringType
+    use GwfGhbInputModule, only: GwfGhbParamFoundType
     ! -- dummy
     class(GhbType), intent(inout) :: this
-    character(len=*), intent(inout) :: option
-    logical, intent(inout) :: found
-! ------------------------------------------------------------------------------
+    ! -- local
+    type(GwfGhbParamFoundType) :: found
     !
-    select case (option)
-    case ('MOVER')
-      this%imover = 1
-      write (this%iout, '(4x,A)') 'MOVER OPTION ENABLED'
-      found = .true.
-    case default
-      !
-      ! -- No options found
-      found = .false.
-    end select
+    ! -- source base class options
+    call this%BndExtType%source_options()
+    !
+    ! -- source options from input context
+    call mem_set_value(this%imover, 'MOVER', this%input_mempath, found%mover)
     !
-    ! -- return
+    ! -- log ghb specific options
+    call this%log_ghb_options(found)
+    !
+    ! -- Return
     return
   end subroutine ghb_options
 
+  !> @brief Log options specific to GhbType
+  !<
+  subroutine log_ghb_options(this, found)
+    ! -- modules
+    use GwfGhbInputModule, only: GwfGhbParamFoundType
+    ! -- dummy
+    class(GhbType), intent(inout) :: this !< BndExtType object
+    type(GwfGhbParamFoundType), intent(in) :: found
+    !
+    ! -- log found options
+    write (this%iout, '(/1x,a)') 'PROCESSING '//trim(adjustl(this%text)) &
+      //' OPTIONS'
+    !
+    if (found%mover) then
+      write (this%iout, '(4x,A)') 'MOVER OPTION ENABLED'
+    end if
+    !
+    ! -- close logging block
+    write (this%iout, '(1x,a)') &
+      'END OF '//trim(adjustl(this%text))//' OPTIONS'
+    !
+    ! -- Return
+    return
+  end subroutine log_ghb_options
+
+  !> @brief Allocate arrays
+  !<
+  subroutine ghb_allocate_arrays(this, nodelist, auxvar)
+    ! -- modules
+    use MemoryManagerModule, only: mem_allocate, mem_setptr, mem_checkin
+    ! -- dummy
+    class(GhbType) :: this
+    integer(I4B), dimension(:), pointer, contiguous, optional :: nodelist
+    real(DP), dimension(:, :), pointer, contiguous, optional :: auxvar
+    !
+    ! -- call base type allocate arrays
+    call this%BndExtType%allocate_arrays(nodelist, auxvar)
+    !
+    ! -- set ghb input context pointers
+    call mem_setptr(this%bhead, 'BHEAD', this%input_mempath)
+    call mem_setptr(this%cond, 'COND', this%input_mempath)
+    !
+    ! --checkin ghb input context pointers
+    call mem_checkin(this%bhead, 'BHEAD', this%memoryPath, &
+                     'BHEAD', this%input_mempath)
+    call mem_checkin(this%cond, 'COND', this%memoryPath, &
+                     'COND', this%input_mempath)
+    !
+    ! -- Return
+    return
+  end subroutine ghb_allocate_arrays
+
+  !> @brief Read and prepare
+  !<
+  subroutine ghb_rp(this)
+    ! -- modules
+    use TdisModule, only: kper
+    ! -- dummy
+    class(GhbType), intent(inout) :: this
+    !
+    if (this%iper /= kper) return
+    !
+    ! -- Call the parent class read and prepare
+    call this%BndExtType%bnd_rp()
+    !
+    ! -- store user cond
+    if (this%ivsc == 1) then
+      call this%ghb_store_user_cond()
+    end if
+    !
+    ! -- Write the list to iout if requested
+    if (this%iprpak /= 0) then
+      call this%write_list()
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine ghb_rp
+
+  !> @brief Check ghb boundary condition data
+  !<
   subroutine ghb_ck(this)
-! ******************************************************************************
-! ghb_ck -- Check ghb boundary condition data
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error, count_errors, store_error_unit
@@ -131,15 +221,14 @@ subroutine ghb_ck(this)
     character(len=*), parameter :: fmtghberr = &
       "('GHB BOUNDARY (',i0,') HEAD (',f10.3,') IS LESS THAN CELL &
       &BOTTOM (',f10.3,')')"
-! ------------------------------------------------------------------------------
     !
     ! -- check stress period data
     do i = 1, this%nbound
       node = this%nodelist(i)
       bt = this%dis%bot(node)
       ! -- accumulate errors
-      if (this%bound(1, i) < bt .and. this%icelltype(node) /= 0) then
-        write (errmsg, fmt=fmtghberr) i, this%bound(1, i), bt
+      if (this%bhead(i) < bt .and. this%icelltype(node) /= 0) then
+        write (errmsg, fmt=fmtghberr) i, this%bhead(i), bt
         call store_error(errmsg)
       end if
     end do
@@ -149,37 +238,23 @@ subroutine ghb_ck(this)
       call store_error_unit(this%inunit)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine ghb_ck
 
-  subroutine ghb_cf(this, reset_mover)
-! ******************************************************************************
-! ghb_cf -- Formulate the HCOF and RHS terms
-! Subroutine: (1) skip if no ghbs
-!             (2) calculate hcof and rhs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Formulate the HCOF and RHS terms
+  !!
+  !! Skip if no GHBs
+  !<
+  subroutine ghb_cf(this)
     ! -- dummy
     class(GhbType) :: this
-    logical, intent(in), optional :: reset_mover
     ! -- local
     integer(I4B) :: i, node
-    logical :: lrm
-! ------------------------------------------------------------------------------
     !
     ! -- Return if no ghbs
     if (this%nbound .eq. 0) return
     !
-    ! -- packmvrobj cf
-    lrm = .true.
-    if (present(reset_mover)) lrm = reset_mover
-    if (this%imover == 1 .and. lrm) then
-      call this%pakmvrobj%cf()
-    end if
-    !
     ! -- Calculate hcof and rhs for each ghb entry
     do i = 1, this%nbound
       node = this%nodelist(i)
@@ -188,21 +263,17 @@ subroutine ghb_cf(this, reset_mover)
         this%rhs(i) = DZERO
         cycle
       end if
-      this%hcof(i) = -this%bound(2, i)
-      this%rhs(i) = -this%bound(2, i) * this%bound(1, i)
+      this%hcof(i) = -this%cond_mult(i)
+      this%rhs(i) = -this%cond_mult(i) * this%bhead(i)
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine ghb_cf
 
+  !> @brief Copy rhs and hcof into solution rhs and amat
+  !<
   subroutine ghb_fc(this, rhs, ia, idxglo, matrix_sln)
-! **************************************************************************
-! ghb_fc -- Copy rhs and hcof into solution rhs and amat
-! **************************************************************************
-!
-!    SPECIFICATIONS:
-! --------------------------------------------------------------------------
     ! -- dummy
     class(GhbType) :: this
     real(DP), dimension(:), intent(inout) :: rhs
@@ -212,7 +283,6 @@ subroutine ghb_fc(this, rhs, ia, idxglo, matrix_sln)
     ! -- local
     integer(I4B) :: i, n, ipos
     real(DP) :: cond, bhead, qghb
-! --------------------------------------------------------------------------
     !
     ! -- pakmvrobj fc
     if (this%imover == 1) then
@@ -228,28 +298,24 @@ subroutine ghb_fc(this, rhs, ia, idxglo, matrix_sln)
       !
       ! -- If mover is active and this boundary is discharging,
       !    store available water (as positive value).
-      bhead = this%bound(1, i)
+      bhead = this%bhead(i)
       if (this%imover == 1 .and. this%xnew(n) > bhead) then
-        cond = this%bound(2, i)
+        cond = this%cond_mult(i)
         qghb = cond * (this%xnew(n) - bhead)
         call this%pakmvrobj%accumulate_qformvr(i, qghb)
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine ghb_fc
 
+  !> @brief Define the list heading that is written to iout when PRINT_INPUT
+  !! option is used
+  !<
   subroutine define_listlabel(this)
-! ******************************************************************************
-! define_listlabel -- Define the list heading that is written to iout when
-!   PRINT_INPUT option is used.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     class(GhbType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- create the header list label
     this%listlabel = trim(this%filtyp)//' NO.'
@@ -269,43 +335,38 @@ subroutine define_listlabel(this)
       write (this%listlabel, '(a, a16)') trim(this%listlabel), 'BOUNDARY NAME'
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine define_listlabel
 
   ! -- Procedures related to observations
 
+  !> @brief Return true because GHB package supports observations
+  !!
+  !! Overrides BndType%bnd_obs_supported()
+  !<
   logical function ghb_obs_supported(this)
-    ! ******************************************************************************
-    ! ghb_obs_supported
-    !   -- Return true because GHB package supports observations.
-    !   -- Overrides BndType%bnd_obs_supported()
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
     implicit none
+    ! -- dummy
     class(GhbType) :: this
-    ! ------------------------------------------------------------------------------
+    !
     ghb_obs_supported = .true.
+    !
+    ! -- Return
     return
   end function ghb_obs_supported
 
+  !> @brief Store observation type supported by GHB package
+  !!
+  !! Overrides BndType%bnd_df_obs
+  !<
   subroutine ghb_df_obs(this)
-    ! ******************************************************************************
-    ! ghb_df_obs (implements bnd_df_obs)
-    !   -- Store observation type supported by GHB package.
-    !   -- Overrides BndType%bnd_df_obs
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
     implicit none
     ! -- dummy
     class(GhbType) :: this
     ! -- local
     integer(I4B) :: indx
-    ! ------------------------------------------------------------------------------
+    !
     call this%obs%StoreObsType('ghb', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => DefaultObsIdProcessor
     !
@@ -314,37 +375,74 @@ subroutine ghb_df_obs(this)
     call this%obs%StoreObsType('to-mvr', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => DefaultObsIdProcessor
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine ghb_df_obs
-  !
-  ! -- Procedure related to time series
-  !
-  subroutine ghb_rp_ts(this)
-    ! -- Assign tsLink%Text appropriately for
-    !    all time series in use by package.
-    !    In GHB package variables BHEAD and COND
-    !    can be controlled by time series.
+
+  !> @brief Store user-specified conductance for GHB boundary type
+  !<
+  subroutine ghb_store_user_cond(this)
     ! -- dummy
-    class(GhbType), intent(inout) :: this
+    class(GhbType), intent(inout) :: this !< BndExtType object
     ! -- local
-    integer(I4B) :: i, nlinks
-    type(TimeSeriesLinkType), pointer :: tslink => null()
-    !
-    nlinks = this%TsManager%boundtslinks%Count()
-    do i = 1, nlinks
-      tslink => GetTimeSeriesLinkFromList(this%TsManager%boundtslinks, i)
-      if (associated(tslink)) then
-        select case (tslink%JCol)
-        case (1)
-          tslink%Text = 'BHEAD'
-        case (2)
-          tslink%Text = 'COND'
-        end select
-      end if
+    integer(I4B) :: n
+    !
+    ! -- store backup copy of conductance values
+    do n = 1, this%nbound
+      this%condinput(n) = this%cond_mult(n)
     end do
     !
+    ! -- Return
+    return
+  end subroutine ghb_store_user_cond
+
+  !> @brief Apply multiplier to GHB conductance if option AUXMULTCOL is used
+  !<
+  function cond_mult(this, row) result(cond)
+    ! -- modules
+    use ConstantsModule, only: DZERO
+    ! -- dummy variables
+    class(GhbType), intent(inout) :: this !< BndExtType object
+    integer(I4B), intent(in) :: row
+    ! -- result
+    real(DP) :: cond
+    !
+    if (this%iauxmultcol > 0) then
+      cond = this%cond(row) * this%auxvar(this%iauxmultcol, row)
+    else
+      cond = this%cond(row)
+    end if
+    !
+    ! -- Return
+    return
+  end function cond_mult
+
+  !> @brief Return requested boundary value
+  !<
+  function ghb_bound_value(this, col, row) result(bndval)
+    ! -- modules
+    use ConstantsModule, only: DZERO
+    ! -- dummy
+    class(GhbType), intent(inout) :: this !< BndExtType object
+    integer(I4B), intent(in) :: col
+    integer(I4B), intent(in) :: row
+    ! -- result
+    real(DP) :: bndval
+    !
+    select case (col)
+    case (1)
+      bndval = this%bhead(row)
+    case (2)
+      bndval = this%cond_mult(row)
+    case default
+      errmsg = 'Programming error. GHB bound value requested column '&
+               &'outside range of ncolbnd (2).'
+      call store_error(errmsg)
+      call store_error_filename(this%input_fname)
+    end select
+    !
+    ! -- Return
     return
-  end subroutine ghb_rp_ts
+  end function ghb_bound_value
 
 end module ghbmodule
diff --git a/src/Model/GroundWaterFlow/gwf3ghb8idm.f90 b/src/Model/GroundWaterFlow/gwf3ghb8idm.f90
new file mode 100644
index 00000000000..2774d26c883
--- /dev/null
+++ b/src/Model/GroundWaterFlow/gwf3ghb8idm.f90
@@ -0,0 +1,449 @@
+! ** Do Not Modify! MODFLOW 6 system generated file. **
+module GwfGhbInputModule
+  use ConstantsModule, only: LENVARNAME
+  use InputDefinitionModule, only: InputParamDefinitionType, &
+                                   InputBlockDefinitionType
+  private
+  public gwf_ghb_param_definitions
+  public gwf_ghb_aggregate_definitions
+  public gwf_ghb_block_definitions
+  public GwfGhbParamFoundType
+  public gwf_ghb_multi_package
+
+  type GwfGhbParamFoundType
+    logical :: auxiliary = .false.
+    logical :: auxmultname = .false.
+    logical :: boundnames = .false.
+    logical :: iprpak = .false.
+    logical :: iprflow = .false.
+    logical :: ipakcb = .false.
+    logical :: ts_filerecord = .false.
+    logical :: ts6 = .false.
+    logical :: filein = .false.
+    logical :: ts6_filename = .false.
+    logical :: obs_filerecord = .false.
+    logical :: obs6 = .false.
+    logical :: obs6_filename = .false.
+    logical :: mover = .false.
+    logical :: maxbound = .false.
+    logical :: cellid = .false.
+    logical :: bhead = .false.
+    logical :: cond = .false.
+    logical :: auxvar = .false.
+    logical :: boundname = .false.
+  end type GwfGhbParamFoundType
+
+  logical :: gwf_ghb_multi_package = .true.
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_auxiliary = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXILIARY', & ! tag name
+    'AUXILIARY', & ! fortran variable
+    'STRING', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_auxmultname = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXMULTNAME', & ! tag name
+    'AUXMULTNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_boundnames = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'OPTIONS', & ! block
+    'BOUNDNAMES', & ! tag name
+    'BOUNDNAMES', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_iprpak = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_INPUT', & ! tag name
+    'IPRPAK', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_iprflow = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_FLOWS', & ! tag name
+    'IPRFLOW', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_ipakcb = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'OPTIONS', & ! block
+    'SAVE_FLOWS', & ! tag name
+    'IPAKCB', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_ts_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS_FILERECORD', & ! tag name
+    'TS_FILERECORD', & ! fortran variable
+    'RECORD TS6 FILEIN TS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_ts6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS6', & ! tag name
+    'TS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_filein = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'OPTIONS', & ! block
+    'FILEIN', & ! tag name
+    'FILEIN', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_ts6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS6_FILENAME', & ! tag name
+    'TS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_obs_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS_FILERECORD', & ! tag name
+    'OBS_FILERECORD', & ! fortran variable
+    'RECORD OBS6 FILEIN OBS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_obs6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6', & ! tag name
+    'OBS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_obs6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6_FILENAME', & ! tag name
+    'OBS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_mover = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'OPTIONS', & ! block
+    'MOVER', & ! tag name
+    'MOVER', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_maxbound = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'DIMENSIONS', & ! block
+    'MAXBOUND', & ! tag name
+    'MAXBOUND', & ! fortran variable
+    'INTEGER', & ! type
+    '', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_cellid = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'PERIOD', & ! block
+    'CELLID', & ! tag name
+    'CELLID', & ! fortran variable
+    'INTEGER1D', & ! type
+    'NCELLDIM', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_bhead = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'PERIOD', & ! block
+    'BHEAD', & ! tag name
+    'BHEAD', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_cond = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'PERIOD', & ! block
+    'COND', & ! tag name
+    'COND', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_auxvar = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'PERIOD', & ! block
+    'AUX', & ! tag name
+    'AUXVAR', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_boundname = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'PERIOD', & ! block
+    'BOUNDNAME', & ! tag name
+    'BOUNDNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_ghb_param_definitions(*) = &
+    [ &
+    gwfghb_auxiliary, &
+    gwfghb_auxmultname, &
+    gwfghb_boundnames, &
+    gwfghb_iprpak, &
+    gwfghb_iprflow, &
+    gwfghb_ipakcb, &
+    gwfghb_ts_filerecord, &
+    gwfghb_ts6, &
+    gwfghb_filein, &
+    gwfghb_ts6_filename, &
+    gwfghb_obs_filerecord, &
+    gwfghb_obs6, &
+    gwfghb_obs6_filename, &
+    gwfghb_mover, &
+    gwfghb_maxbound, &
+    gwfghb_cellid, &
+    gwfghb_bhead, &
+    gwfghb_cond, &
+    gwfghb_auxvar, &
+    gwfghb_boundname &
+    ]
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfghb_spd = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'GHB', & ! subcomponent
+    'PERIOD', & ! block
+    'STRESS_PERIOD_DATA', & ! tag name
+    'SPD', & ! fortran variable
+    'RECARRAY CELLID BHEAD COND AUX BOUNDNAME', & ! type
+    'MAXBOUND', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_ghb_aggregate_definitions(*) = &
+    [ &
+    gwfghb_spd &
+    ]
+
+  type(InputBlockDefinitionType), parameter :: &
+    gwf_ghb_block_definitions(*) = &
+    [ &
+    InputBlockDefinitionType( &
+    'OPTIONS', & ! blockname
+    .false., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'DIMENSIONS', & ! blockname
+    .true., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'PERIOD', & ! blockname
+    .true., & ! required
+    .true., & ! aggregate
+    .true. & ! block_variable
+    ) &
+    ]
+
+end module GwfGhbInputModule
diff --git a/src/Model/GroundWaterFlow/gwf3hfb8.f90 b/src/Model/GroundWaterFlow/gwf3hfb8.f90
index 8fc3199f551..76f951a75e5 100644
--- a/src/Model/GroundWaterFlow/gwf3hfb8.f90
+++ b/src/Model/GroundWaterFlow/gwf3hfb8.f90
@@ -45,6 +45,7 @@ module GwfHfbModule
     integer(I4B), pointer :: ivsc => null() !< flag indicating if viscosity is active in the model
 
   contains
+
     procedure :: hfb_ar
     procedure :: hfb_rp
     procedure :: hfb_fc
@@ -63,19 +64,14 @@ module GwfHfbModule
 
 contains
 
+  !> @brief Create a new hfb object
+  !<
   subroutine hfb_cr(hfbobj, name_model, inunit, iout)
-! ******************************************************************************
-! hfb_cr -- Create a new hfb object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(GwfHfbType), pointer :: hfbobj
     character(len=*), intent(in) :: name_model
     integer(I4B), intent(in) :: inunit
     integer(I4B), intent(in) :: iout
-! ------------------------------------------------------------------------------
     !
     ! -- Create the object
     allocate (hfbobj)
@@ -97,13 +93,9 @@ subroutine hfb_cr(hfbobj, name_model, inunit, iout)
     return
   end subroutine hfb_cr
 
+  !> @brief Allocate and read
+  !<
   subroutine hfb_ar(this, ibound, xt3d, dis, invsc, vsc)
-! ******************************************************************************
-! hfb_ar -- Allocate and read
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_setptr
     use MemoryHelperModule, only: create_mem_path
@@ -114,12 +106,10 @@ subroutine hfb_ar(this, ibound, xt3d, dis, invsc, vsc)
     class(DisBaseType), pointer, intent(inout) :: dis !< discretization package
     integer(I4B), pointer :: invsc !< indicates if viscosity package is active
     type(GwfVscType), pointer, intent(in) :: vsc !< viscosity package
-    ! -- local
     ! -- formats
     character(len=*), parameter :: fmtheader = &
       "(1x, /1x, 'HFB -- HORIZONTAL FLOW BARRIER PACKAGE, VERSION 8, ', &
       &'4/24/2015 INPUT READ FROM UNIT ', i4, //)"
-! ------------------------------------------------------------------------------
     !
     ! -- Print a message identifying the node property flow package.
     write (this%iout, fmtheader) this%inunit
@@ -128,7 +118,7 @@ subroutine hfb_ar(this, ibound, xt3d, dis, invsc, vsc)
     this%dis => dis
     this%ibound => ibound
     this%xt3d => xt3d
-
+    !
     call mem_setptr(this%icelltype, 'ICELLTYPE', &
                     create_mem_path(this%name_model, 'NPF'))
     call mem_setptr(this%ihc, 'IHC', create_mem_path(this%name_model, 'CON'))
@@ -156,17 +146,13 @@ subroutine hfb_ar(this, ibound, xt3d, dis, invsc, vsc)
         trim(this%filtyp)//' Package calculations: '//trim(adjustl(this%packName))
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine hfb_ar
 
+  !> @brief Check for new HFB stress period data
+  !<
   subroutine hfb_rp(this)
-! ******************************************************************************
-! hfb_rp -- Check for new hfb stress period data
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error, count_errors, store_error_unit
@@ -182,7 +168,6 @@ subroutine hfb_rp(this)
       &"('Error.  Looking for BEGIN PERIOD iper.  Found ', a, ' instead.')"
     character(len=*), parameter :: fmtlsp = &
       &"(1X,/1X,'REUSING ',A,'S FROM LAST STRESS PERIOD')"
-! ------------------------------------------------------------------------------
     !
     ! -- Set ionper to the stress period number for which a new block of data
     !    will be read.
@@ -220,21 +205,19 @@ subroutine hfb_rp(this)
       write (this%iout, fmtlsp) 'HFB'
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine hfb_rp
 
+  !> @brief Fill matrix terms
+  !!
+  !! Fill amatsln for the following conditions:
+  !!   1. XT3D
+  !!     OR
+  !!   2. Not Newton, and
+  !!   3. Cell type n is convertible or cell type m is convertible
+  !<
   subroutine hfb_fc(this, kiter, matrix_sln, idxglo, rhs, hnew)
-! ******************************************************************************
-! hfb_fc -- Fill amatsln for the following conditions:
-!   1.  Not Newton, and
-!   2.  Cell type n is convertible or cell type m is convertible
-!  OR
-!   3.  XT3D
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DHALF, DZERO, DONE
     ! -- dummy
@@ -254,7 +237,6 @@ subroutine hfb_fc(this, kiter, matrix_sln, idxglo, rhs, hnew)
     real(DP) :: fawidth, faheight
     real(DP) :: topn, topm, botn, botm
     real(DP) :: viscratio
-! ------------------------------------------------------------------------------
     !
     ! -- initialize variables
     viscratio = DONE
@@ -373,19 +355,16 @@ subroutine hfb_fc(this, kiter, matrix_sln, idxglo, rhs, hnew)
       !
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine hfb_fc
 
+  !> @brief flowja will automatically include the effects of the hfb for
+  !! confined and newton cases when xt3d is not used.
+  !!
+  !! This method recalculates flowja for the other cases.
+  !<
   subroutine hfb_cq(this, hnew, flowja)
-! ******************************************************************************
-! hfb_cq -- flowja will automatically include the effects of the hfb
-!   for confined and newton cases when xt3d is not used.  This method
-!   recalculates flowja for the other cases.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DHALF, DZERO, DONE
     ! -- dummy
@@ -402,8 +381,7 @@ subroutine hfb_cq(this, hnew, flowja)
     real(DP) :: fawidth, faheight
     real(DP) :: topn, topm, botn, botm
     real(DP) :: viscratio
-! ------------------------------------------------------------------------------
-!
+    !
     ! -- initialize viscratio
     viscratio = DONE
     !
@@ -482,24 +460,17 @@ subroutine hfb_cq(this, hnew, flowja)
       !
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine hfb_cq
 
+  !> @brief Deallocate memory
+  !<
   subroutine hfb_da(this)
-! ******************************************************************************
-! hfb_da -- Deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(GwfHfbType) :: this
-! ------------------------------------------------------------------------------
-    !
-    ! -- Strings
     !
     ! -- Scalars
     call mem_deallocate(this%maxhfb)
@@ -535,22 +506,17 @@ subroutine hfb_da(this)
     this%hwva => null()
     this%vsc => null()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine hfb_da
 
+  !> @brief Allocate package scalars
+  !<
   subroutine allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars -- Allocate scalars
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwfHfbType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- allocate scalars in NumericalPackageType
     call this%NumericalPackageType%allocate_scalars()
@@ -567,24 +533,19 @@ subroutine allocate_scalars(this)
     this%nhfb = 0
     this%ivsc = 0
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine allocate_scalars
 
+  !> @brief Allocate package arrays
+  !<
   subroutine allocate_arrays(this)
-! ******************************************************************************
-! allocate_arrays -- Allocate arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwfHfbType) :: this
     ! -- local
     integer(I4B) :: ihfb
-! ------------------------------------------------------------------------------
     !
     call mem_allocate(this%noden, this%maxhfb, 'NODEN', this%memoryPath)
     call mem_allocate(this%nodem, this%maxhfb, 'NODEM', this%memoryPath)
@@ -598,17 +559,13 @@ subroutine allocate_arrays(this)
       this%idxloc(ihfb) = 0
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine allocate_arrays
 
+  !> @brief Read a hfb options block
+  !<
   subroutine read_options(this)
-! ******************************************************************************
-! read_options -- read a hfb options block
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error, store_error_unit
@@ -618,7 +575,6 @@ subroutine read_options(this)
     character(len=LINELENGTH) :: errmsg, keyword
     integer(I4B) :: ierr
     logical :: isfound, endOfBlock
-! ------------------------------------------------------------------------------
     !
     ! -- get options block
     call this%parser%GetBlock('OPTIONS', isfound, ierr, &
@@ -646,17 +602,13 @@ subroutine read_options(this)
       write (this%iout, '(1x,a)') 'END OF HFB OPTIONS'
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine read_options
 
+  !> @brief Read the dimensions for this package
+  !<
   subroutine read_dimensions(this)
-! ******************************************************************************
-! read_dimensions -- Read the dimensions for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error, store_error_unit
     ! -- dummy
@@ -665,8 +617,6 @@ subroutine read_dimensions(this)
     character(len=LINELENGTH) :: errmsg, keyword
     integer(I4B) :: ierr
     logical :: isfound, endOfBlock
-    ! -- format
-! ------------------------------------------------------------------------------
     !
     ! -- get dimensions block
     call this%parser%GetBlock('DIMENSIONS', isfound, ierr, &
@@ -705,20 +655,18 @@ subroutine read_dimensions(this)
       call this%parser%StoreErrorUnit()
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine read_dimensions
 
+  !> @brief Read HFB period block
+  !!
+  !! Data are in form of:
+  !!   L, IROW1, ICOL1, IROW2, ICOL2, HYDCHR
+  !! or for unstructured:
+  !!   N1, N2, HYDCHR
+  !<
   subroutine read_data(this)
-! ******************************************************************************
-! read_data -- Read hfb period block
-!   Data are in form of L, IROW1, ICOL1, IROW2, ICOL2, HYDCHR
-!   or for unstructured
-!                       N1, N2, HYDCHR
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error, count_errors, store_error_unit
@@ -731,7 +679,6 @@ subroutine read_data(this)
     logical :: endOfBlock
     ! -- formats
     character(len=*), parameter :: fmthfb = "(i10, 2a10, 1(1pg15.6))"
-! ------------------------------------------------------------------------------
     !
     write (this%iout, '(//,1x,a)') 'READING HFB DATA'
     if (this%iprpak > 0) then
@@ -786,18 +733,15 @@ subroutine read_data(this)
     call this%check_data()
     write (this%iout, '(1x,a)') 'END READING HFB DATA'
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine read_data
 
+  !> @brief Check for hfb's between two unconnected cells and write a warning
+  !!
+  !! Store ipos in idxloc
+  !<
   subroutine check_data(this)
-! ******************************************************************************
-! check_data -- Check for hfb's between two unconnected cells and write a
-!   warning.  Store ipos in idxloc.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error, count_errors, store_error_unit
@@ -814,7 +758,6 @@ subroutine check_data(this)
       &' is between two unconnected cells: ', a, ' and ', a)"
     character(len=*), parameter :: fmtverr = "(1x, 'HFB no. ',i0, &
       &' is between two cells not horizontally connected: ', a, ' and ', a)"
-! ------------------------------------------------------------------------------
     !
     do ihfb = 1, this%nhfb
       n = this%noden(ihfb)
@@ -854,43 +797,35 @@ subroutine check_data(this)
       call store_error_unit(this%inunit)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine check_data
 
+  !> @brief Reset condsat to its value prior to being modified by hfb's
+  !<
   subroutine condsat_reset(this)
-! ******************************************************************************
-! condsat_reset -- Reset condsat to its value prior to being modified by hfb's
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfHfbType) :: this
     ! -- local
     integer(I4B) :: ihfb
     integer(I4B) :: ipos
-! ------------------------------------------------------------------------------
     !
     do ihfb = 1, this%nhfb
       ipos = this%idxloc(ihfb)
       this%condsat(this%jas(ipos)) = this%csatsav(ihfb)
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine condsat_reset
 
+  !> @brief Modify condsat
+  !!
+  !! Modify condsat for the following conditions:
+  !!   1.  If Newton is active
+  !!   2.  If icelltype for n and icelltype for m is 0
+  !<
   subroutine condsat_modify(this)
-! ******************************************************************************
-! condsat_modify -- Modify condsat for the following conditions:
-!   1.  If Newton is active
-!   2.  If icelltype for n and icelltype for m is 0
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DHALF, DZERO
     ! -- dummy
@@ -901,7 +836,6 @@ subroutine condsat_modify(this)
     real(DP) :: cond, condhfb
     real(DP) :: fawidth, faheight
     real(DP) :: topn, topm, botn, botm
-! ------------------------------------------------------------------------------
     !
     do ihfb = 1, this%nhfb
       ipos = this%idxloc(ihfb)
@@ -935,7 +869,7 @@ subroutine condsat_modify(this)
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine condsat_modify
 
diff --git a/src/Model/GroundWaterFlow/gwf3ic8.f90 b/src/Model/GroundWaterFlow/gwf3ic8.f90
index 033f565819b..8d51e717aa7 100644
--- a/src/Model/GroundWaterFlow/gwf3ic8.f90
+++ b/src/Model/GroundWaterFlow/gwf3ic8.f90
@@ -1,6 +1,7 @@
 module GwfIcModule
 
-  use KindModule, only: DP, I4B
+  use KindModule, only: DP, I4B, LGP
+  use ConstantsModule, only: LINELENGTH
   use NumericalPackageModule, only: NumericalPackageType
   use BlockParserModule, only: BlockParserType
   use BaseDisModule, only: DisBaseType
@@ -11,238 +12,155 @@ module GwfIcModule
   public :: ic_cr
 
   type, extends(NumericalPackageType) :: GwfIcType
+
     real(DP), dimension(:), pointer, contiguous :: strt => null() ! starting head
+
   contains
+
     procedure :: ic_ar
     procedure :: ic_da
+    procedure, private :: ic_load
     procedure, private :: allocate_arrays
-    procedure, private :: read_options
-    procedure :: read_data
+    procedure, private :: source_griddata
+
   end type GwfIcType
 
 contains
 
-  subroutine ic_cr(ic, name_model, inunit, iout, dis)
-! ******************************************************************************
-! ic_cr -- Create a new initial conditions object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Create a new initial conditions object
+  !<
+  subroutine ic_cr(ic, name_model, input_mempath, inunit, iout, dis)
+    ! -- modules
+    use MemoryManagerExtModule, only: mem_set_value
     ! -- dummy
     type(GwfIcType), pointer :: ic
     character(len=*), intent(in) :: name_model
+    character(len=*), intent(in) :: input_mempath
     integer(I4B), intent(in) :: inunit
     integer(I4B), intent(in) :: iout
     class(DisBaseType), pointer, intent(in) :: dis
-! ------------------------------------------------------------------------------
+    ! -- formats
+    character(len=*), parameter :: fmtic = &
+      "(1x, /1x, 'IC -- Initial Conditions Package, Version 8, 3/28/2015', &
+      &' input read from mempath: ', A, //)"
     !
-    ! -- Create the object
+    ! -- create IC object
     allocate (ic)
     !
     ! -- create name and memory path
-    call ic%set_names(1, name_model, 'IC', 'IC')
+    call ic%set_names(1, name_model, 'IC', 'IC', input_mempath)
     !
-    ! -- Allocate scalars
+    ! -- allocate scalars
     call ic%allocate_scalars()
     !
+    ! -- set variables
     ic%inunit = inunit
     ic%iout = iout
     !
     ! -- set pointers
     ic%dis => dis
     !
-    ! -- Initialize block parser
-    call ic%parser%Initialize(ic%inunit, ic%iout)
-    !
-    ! -- Return
-    return
+    ! -- check if pkg is enabled,
+    if (inunit > 0) then
+      ! print message identifying pkg
+      write (ic%iout, fmtic) input_mempath
+    end if
   end subroutine ic_cr
 
-  subroutine ic_ar(this, x)
-! ******************************************************************************
-! ic_ar -- Allocate and read initial conditions
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Load data from IDM into package
+  !<
+  subroutine ic_load(this)
     ! -- modules
     use BaseDisModule, only: DisBaseType
-    use SimModule, only: store_error
+    ! -- dummy
+    class(GwfIcType) :: this
+    !
+    call this%source_griddata()
+  end subroutine ic_load
+
+  !> @brief Allocate arrays, load from IDM, and assign head
+  !<
+  subroutine ic_ar(this, x)
     ! -- dummy
     class(GwfIcType) :: this
     real(DP), dimension(:), intent(inout) :: x
-    ! -- locals
+    ! -- local
     integer(I4B) :: n
-! ------------------------------------------------------------------------------
-    !
-    ! -- Print a message identifying the initial conditions package.
-    write (this%iout, 1) this%inunit
-1   format(1x, /1x, 'IC -- INITIAL CONDITIONS PACKAGE, VERSION 8, 3/28/2015', &
-           ' INPUT READ FROM UNIT ', i0)
     !
-    ! -- Allocate arrays
+    ! -- allocate arrays
     call this%allocate_arrays(this%dis%nodes)
     !
-    ! -- Read options
-    call this%read_options()
+    ! -- load from IDM
+    call this%ic_load()
     !
-    ! -- Read data
-    call this%read_data()
-    !
-    ! -- Assign x equal to strt
+    ! -- assign starting head
     do n = 1, this%dis%nodes
       x(n) = this%strt(n)
     end do
-    !
-    ! -- Return
-    return
   end subroutine ic_ar
 
+  !> @brief Deallocate
+  !<
   subroutine ic_da(this)
-! ******************************************************************************
-! ic_da -- Deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
+    use MemoryManagerExtModule, only: memorylist_remove
+    use SimVariablesModule, only: idm_context
     ! -- dummy
     class(GwfIcType) :: this
-! ------------------------------------------------------------------------------
     !
-    ! -- deallocate parent
-    call this%NumericalPackageType%da()
-    !
-    ! -- Scalars
+    ! -- deallocate IDM memory
+    call memorylist_remove(this%name_model, 'IC', idm_context)
     !
-    ! -- Arrays
+    ! -- deallocate arrays
     call mem_deallocate(this%strt)
     !
-    ! -- Return
-    return
+    ! -- deallocate parent
+    call this%NumericalPackageType%da()
   end subroutine ic_da
 
+  !> @brief Allocate arrays
+  !<
   subroutine allocate_arrays(this, nodes)
-! ******************************************************************************
-! allocate_arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwfIcType) :: this
     integer(I4B), intent(in) :: nodes
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate
     call mem_allocate(this%strt, nodes, 'STRT', this%memoryPath)
-    !
-    ! -- Return
-    return
   end subroutine allocate_arrays
 
-  subroutine read_options(this)
-! ******************************************************************************
-! read_options
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Copy grid data from IDM into package
+  !<
+  subroutine source_griddata(this)
     ! -- modules
-    use ConstantsModule, only: LINELENGTH
-    use SimModule, only: store_error
+    use SimModule, only: store_error, store_error_filename
+    use MemoryManagerExtModule, only: mem_set_value
+    use GwfIcInputModule, only: GwfIcParamFoundType
     ! -- dummy
     class(GwfIcType) :: this
     ! -- local
-    character(len=LINELENGTH) :: errmsg, keyword
-    integer(I4B) :: ierr
-    logical :: isfound, endOfBlock
-    ! -- formats
-! ------------------------------------------------------------------------------
-    !
-    ! -- get options block
-    call this%parser%GetBlock('OPTIONS', isfound, ierr, &
-                              supportOpenClose=.true., blockRequired=.false.)
-    !
-    ! -- parse options block if detected
-    if (isfound) then
-      write (this%iout, '(1x,a)') 'PROCESSING IC OPTIONS'
-      do
-        call this%parser%GetNextLine(endOfBlock)
-        if (endOfBlock) exit
-        call this%parser%GetStringCaps(keyword)
-        select case (keyword)
-        case default
-          write (errmsg, '(a,a)') 'Unknown IC option: ', trim(keyword)
-          call store_error(errmsg)
-          call this%parser%StoreErrorUnit()
-        end select
-      end do
-      write (this%iout, '(1x,a)') 'END OF IC OPTIONS'
+    character(len=LINELENGTH) :: errmsg
+    type(GwfIcParamFoundType) :: found
+    integer(I4B), dimension(:), pointer, contiguous :: map
+    !
+    ! -- set map to convert user to reduced node data
+    map => null()
+    if (this%dis%nodes < this%dis%nodesuser) map => this%dis%nodeuser
+    !
+    ! -- set values
+    call mem_set_value(this%strt, 'STRT', this%input_mempath, map, found%strt)
+    !
+    ! -- ensure STRT was found
+    if (.not. found%strt) then
+      write (errmsg, '(a)') 'Error in GRIDDATA block: STRT not found.'
+      call store_error(errmsg, terminate=.false.)
+      call store_error_filename(this%input_fname)
+    else if (this%iout > 0) then
+      write (this%iout, '(4x,a)') 'STRT set from input file'
     end if
-    !
-    ! -- Return
-    return
-  end subroutine read_options
-
-  subroutine read_data(this)
-! ******************************************************************************
-! read_data
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use ConstantsModule, only: LINELENGTH
-    use SimModule, only: store_error
-    ! -- dummy
-    class(GwfIcType) :: this
-    ! -- local
-    character(len=LINELENGTH) :: errmsg, keyword
-    character(len=:), allocatable :: line
-    integer(I4B) :: istart, istop, lloc, ierr
-    logical :: isfound, endOfBlock
-    character(len=24) :: aname(1)
-    ! -- formats
-! ------------------------------------------------------------------------------
-    !
-    ! -- Setup the label
-    aname(1) = '    INITIAL HEAD'
-    !
-    ! -- get griddata block
-    call this%parser%GetBlock('GRIDDATA', isfound, ierr)
-    if (isfound) then
-      write (this%iout, '(1x,a)') 'PROCESSING GRIDDATA'
-      do
-        call this%parser%GetNextLine(endOfBlock)
-        if (endOfBlock) exit
-        call this%parser%GetStringCaps(keyword)
-        call this%parser%GetRemainingLine(line)
-        lloc = 1
-        select case (keyword)
-        case ('STRT')
-          call this%dis%read_grid_array(line, lloc, istart, istop, this%iout, &
-                                        this%parser%iuactive, this%strt, &
-                                        aname(1))
-        case default
-          write (errmsg, '(a,a)') 'Unknown GRIDDATA tag: ', trim(keyword)
-          call store_error(errmsg)
-          call this%parser%StoreErrorUnit()
-        end select
-      end do
-      write (this%iout, '(1x,a)') 'END PROCESSING GRIDDATA'
-    else
-      call store_error('Required GRIDDATA block not found.')
-      call this%parser%StoreErrorUnit()
-    end if
-    !
-    ! -- Return
-    return
-  end subroutine read_data
+  end subroutine source_griddata
 
 end module GwfIcModule
diff --git a/src/Model/GroundWaterFlow/gwf3ic8idm.f90 b/src/Model/GroundWaterFlow/gwf3ic8idm.f90
new file mode 100644
index 00000000000..f943a35dc98
--- /dev/null
+++ b/src/Model/GroundWaterFlow/gwf3ic8idm.f90
@@ -0,0 +1,79 @@
+! ** Do Not Modify! MODFLOW 6 system generated file. **
+module GwfIcInputModule
+  use ConstantsModule, only: LENVARNAME
+  use InputDefinitionModule, only: InputParamDefinitionType, &
+                                   InputBlockDefinitionType
+  private
+  public gwf_ic_param_definitions
+  public gwf_ic_aggregate_definitions
+  public gwf_ic_block_definitions
+  public GwfIcParamFoundType
+  public gwf_ic_multi_package
+
+  type GwfIcParamFoundType
+    logical :: strt = .false.
+  end type GwfIcParamFoundType
+
+  logical :: gwf_ic_multi_package = .false.
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfic_strt = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'IC', & ! subcomponent
+    'GRIDDATA', & ! block
+    'STRT', & ! tag name
+    'STRT', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NODES', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .true., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_ic_param_definitions(*) = &
+    [ &
+    gwfic_strt &
+    ]
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_ic_aggregate_definitions(*) = &
+    [ &
+    InputParamDefinitionType &
+    ( &
+    '', & ! component
+    '', & ! subcomponent
+    '', & ! block
+    '', & ! tag name
+    '', & ! fortran variable
+    '', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    ) &
+    ]
+
+  type(InputBlockDefinitionType), parameter :: &
+    gwf_ic_block_definitions(*) = &
+    [ &
+    InputBlockDefinitionType( &
+    'OPTIONS', & ! blockname
+    .false., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'GRIDDATA', & ! blockname
+    .true., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ) &
+    ]
+
+end module GwfIcInputModule
diff --git a/src/Model/GroundWaterFlow/gwf3idm.f90 b/src/Model/GroundWaterFlow/gwf3idm.f90
index 0aaf3b5ac74..8b8acf82eeb 100644
--- a/src/Model/GroundWaterFlow/gwf3idm.f90
+++ b/src/Model/GroundWaterFlow/gwf3idm.f90
@@ -1,5 +1,6 @@
 ! ** Do Not Modify! MODFLOW 6 system generated file. **
 module GwfNamInputModule
+  use ConstantsModule, only: LENVARNAME
   use InputDefinitionModule, only: InputParamDefinitionType, &
                                    InputBlockDefinitionType
   private
@@ -37,7 +38,8 @@ module GwfNamInputModule
     .false., & ! required
     .false., & ! multi-record
     .true., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -53,7 +55,8 @@ module GwfNamInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -69,7 +72,8 @@ module GwfNamInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -85,7 +89,8 @@ module GwfNamInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -101,7 +106,8 @@ module GwfNamInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -117,7 +123,8 @@ module GwfNamInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -133,7 +140,8 @@ module GwfNamInputModule
     .false., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -149,7 +157,8 @@ module GwfNamInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -165,7 +174,8 @@ module GwfNamInputModule
     .true., & ! required
     .true., & ! multi-record
     .true., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -181,7 +191,8 @@ module GwfNamInputModule
     .false., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -212,7 +223,8 @@ module GwfNamInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
diff --git a/src/Model/GroundWaterFlow/gwf3lak8.f90 b/src/Model/GroundWaterFlow/gwf3lak8.f90
index 366ebc54e23..3834f640263 100644
--- a/src/Model/GroundWaterFlow/gwf3lak8.f90
+++ b/src/Model/GroundWaterFlow/gwf3lak8.f90
@@ -1,6 +1,6 @@
 module LakModule
   !
-  use KindModule, only: DP, I4B
+  use KindModule, only: DP, I4B, LGP
   use ConstantsModule, only: LINELENGTH, LENBOUNDNAME, LENTIMESERIESNAME, &
                              IWETLAKE, MAXADPIT, &
                              DZERO, DPREC, DEM30, DEM9, DEM6, DEM5, &
@@ -23,13 +23,15 @@ module LakModule
   use TableModule, only: TableType, table_cr
   use ObserveModule, only: ObserveType
   use ObsModule, only: ObsType
-  use InputOutputModule, only: get_node, URWORD, extract_idnum_or_bndname
+  use GeomUtilModule, only: get_node
+  use InputOutputModule, only: URWORD, extract_idnum_or_bndname
   use BaseDisModule, only: DisBaseType
-  use SimModule, only: count_errors, store_error, store_error_unit
-  use GenericUtilitiesModule, only: sim_message, is_same
+  use SimModule, only: count_errors, store_error, store_error_unit, &
+                       deprecation_warning
+  use MathUtilModule, only: is_close
   use BlockParserModule, only: BlockParserType
   use BaseDisModule, only: DisBaseType
-  use SimVariablesModule, only: errmsg
+  use SimVariablesModule, only: errmsg, warnmsg
   use MatrixBaseModule
   !
   implicit none
@@ -199,7 +201,9 @@ module LakModule
     real(DP), dimension(:, :), pointer, contiguous :: viscratios => null() !< viscosity ratios (1: lak vsc ratio; 2: gwf vsc ratio)
     !
     ! -- type bound procedures
+
   contains
+
     procedure :: lak_allocate_scalars
     procedure :: lak_allocate_arrays
     procedure :: bnd_options => lak_options
@@ -282,15 +286,10 @@ module LakModule
 
 contains
 
+  !> @brief Create a new LAK Package and point bndobj to the new package
+  !<
   subroutine lak_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
-! ******************************************************************************
-! lak_create -- Create a New LAKE Package
-! Subroutine: (1) create new-style package
-!             (2) point bndobj to the new package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     class(BndType), pointer :: packobj
     integer(I4B), intent(in) :: id
     integer(I4B), intent(in) :: ibcnum
@@ -298,8 +297,8 @@ subroutine lak_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     integer(I4B), intent(in) :: iout
     character(len=*), intent(in) :: namemodel
     character(len=*), intent(in) :: pakname
+    ! -- local
     type(LakType), pointer :: lakobj
-! ------------------------------------------------------------------------------
     !
     ! -- allocate the object and assign values to object variables
     allocate (lakobj)
@@ -314,7 +313,7 @@ subroutine lak_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     !
     ! -- initialize package
     call packobj%pack_initialize()
-
+    !
     packobj%inunit = inunit
     packobj%iout = iout
     packobj%id = id
@@ -324,20 +323,15 @@ subroutine lak_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     packobj%isadvpak = 1
     packobj%ictMemPath = create_mem_path(namemodel, 'NPF')
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_create
 
+  !> @brief Allocate scalar members
+  !<
   subroutine lak_allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars -- allocate scalar members
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- call standard BndType allocate scalars
     call this%BndType%allocate_scalars()
@@ -392,23 +386,18 @@ subroutine lak_allocate_scalars(this)
     this%idense = 0
     this%ivsc = 0
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_allocate_scalars
 
+  !> @brief Allocate scalar members
+  !<
   subroutine lak_allocate_arrays(this)
-! ******************************************************************************
-! allocate_scalars -- allocate scalar members
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(LakType), intent(inout) :: this
     ! -- local
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     ! -- call standard BndType allocate scalars
     call this%BndType%allocate_arrays()
@@ -464,17 +453,13 @@ subroutine lak_allocate_arrays(this)
     ! -- allocate viscratios to size 0
     call mem_allocate(this%viscratios, 2, 0, 'VISCRATIOS', this%memoryPath)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_allocate_arrays
 
+  !> @brief Read the dimensions for this package
+  !<
   subroutine lak_read_lakes(this)
-! ******************************************************************************
-! pak1read_dimensions -- Read the dimensions for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error, count_errors, store_error_unit
@@ -487,7 +472,7 @@ subroutine lak_read_lakes(this)
     character(len=9) :: cno
     character(len=50), dimension(:), allocatable :: caux
     integer(I4B) :: ierr, ival
-    logical :: isfound, endOfBlock
+    logical(LGP) :: isfound, endOfBlock
     integer(I4B) :: n
     integer(I4B) :: ii, jj
     integer(I4B) :: iaux
@@ -496,9 +481,6 @@ subroutine lak_read_lakes(this)
     integer(I4B) :: nconn
     integer(I4B), dimension(:), pointer, contiguous :: nboundchk
     real(DP), pointer :: bndElem => null()
-    ! -- format
-    !
-    ! -- code
     !
     ! -- initialize itmp
     itmp = 0
@@ -607,39 +589,39 @@ subroutine lak_read_lakes(this)
         call this%parser%GetNextLine(endOfBlock)
         if (endOfBlock) exit
         n = this%parser%GetInteger()
-
+        !
         if (n < 1 .or. n > this%nlakes) then
           write (errmsg, '(a,1x,i0)') 'lakeno MUST BE > 0 and <= ', this%nlakes
           call store_error(errmsg)
           cycle
         end if
-
+        !
         ! -- increment nboundchk
         nboundchk(n) = nboundchk(n) + 1
-
+        !
         ! -- strt
         this%strt(n) = this%parser%GetDouble()
-
+        !
         ! nlakeconn
         ival = this%parser%GetInteger()
-
+        !
         if (ival < 0) then
           write (errmsg, '(a,1x,i0)') 'nlakeconn MUST BE >= 0 for lake ', n
           call store_error(errmsg)
         end if
-
+        !
         nconn = nconn + ival
         this%nlakeconn(n) = ival
-
+        !
         ! -- get aux data
         do iaux = 1, this%naux
           call this%parser%GetString(caux(iaux))
         end do
-
+        !
         ! -- set default bndName
         write (cno, '(i9.9)') n
         bndName = 'Lake'//cno
-
+        !
         ! -- lakename
         if (this%inamedbound /= 0) then
           call this%parser%GetStringCaps(bndNameTemp)
@@ -648,7 +630,7 @@ subroutine lak_read_lakes(this)
           end if
         end if
         this%lakename(n) = bndName
-
+        !
         ! -- fill time series aware data
         ! -- fill aux data
         do jj = 1, this%naux
@@ -660,7 +642,7 @@ subroutine lak_read_lakes(this)
                                              this%tsManager, this%iprpak, &
                                              this%auxname(jj))
         end do
-
+        !
         nlak = nlak + 1
       end do
       !
@@ -675,7 +657,7 @@ subroutine lak_read_lakes(this)
           call store_error(errmsg)
         end if
       end do
-
+      !
       write (this%iout, '(1x,a)') 'END OF '//trim(adjustl(this%text))// &
         ' PACKAGEDATA'
     else
@@ -690,7 +672,7 @@ subroutine lak_read_lakes(this)
     ! -- set MAXBOUND
     this%MAXBOUND = nconn
     write (this%iout, '(//4x,a,i7)') 'MAXBOUND = ', this%maxbound
-
+    !
     ! -- set idxlakeconn
     this%idxlakeconn(1) = 1
     do n = 1, this%nlakes
@@ -705,17 +687,13 @@ subroutine lak_read_lakes(this)
     ! -- deallocate local storage for nboundchk
     deallocate (nboundchk)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_read_lakes
 
+  !> @brief Read the lake connections for this package
+  !<
   subroutine lak_read_lake_connections(this)
-! ******************************************************************************
-! lak_read_lake_connections -- Read the lake connections for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use ConstantsModule, only: LINELENGTH, LENVARNAME
     use SimModule, only: store_error, count_errors
     ! -- dummy
@@ -723,19 +701,17 @@ subroutine lak_read_lake_connections(this)
     ! -- local
     character(len=LINELENGTH) :: keyword, cellid
     integer(I4B) :: ierr, ival
-    logical :: isfound, endOfBlock
+    logical(LGP) :: isfound, endOfBlock
+    logical(LGP) :: is_lake_bed
     real(DP) :: rval
     integer(I4B) :: j, n
     integer(I4B) :: nn
     integer(I4B) :: ipos, ipos0
     integer(I4B) :: icellid, icellid0
-    real(DP) :: top, bot
+    real(DP) :: top
+    real(DP) :: bot
     integer(I4B), dimension(:), pointer, contiguous :: nboundchk
     character(len=LENVARNAME) :: ctypenm
-
-    ! -- format
-    !
-    ! -- code
     !
     ! -- allocate local storage
     allocate (nboundchk(this%MAXBOUND))
@@ -749,7 +725,6 @@ subroutine lak_read_lake_connections(this)
     !
     ! -- parse connectiondata block if detected
     if (isfound) then
-
       ! -- allocate connection data using memory manager
       call mem_allocate(this%imap, this%MAXBOUND, 'IMAP', this%memoryPath)
       call mem_allocate(this%cellid, this%MAXBOUND, 'CELLID', this%memoryPath)
@@ -768,7 +743,7 @@ subroutine lak_read_lake_connections(this)
       call mem_allocate(this%satcond, this%MAXBOUND, 'SATCOND', this%memoryPath)
       call mem_allocate(this%simcond, this%MAXBOUND, 'SIMCOND', this%memoryPath)
       call mem_allocate(this%simlakgw, this%MAXBOUND, 'SIMLAKGW', this%memoryPath)
-
+      !
       ! -- process the lake connection data
       write (this%iout, '(/1x,a)') 'PROCESSING '//trim(adjustl(this%text))// &
         ' LAKE_CONNECTIONS'
@@ -776,13 +751,13 @@ subroutine lak_read_lake_connections(this)
         call this%parser%GetNextLine(endOfBlock)
         if (endOfBlock) exit
         n = this%parser%GetInteger()
-
+        !
         if (n < 1 .or. n > this%nlakes) then
           write (errmsg, '(a,1x,i0)') 'lakeno MUST BE > 0 and <= ', this%nlakes
           call store_error(errmsg)
           cycle
         end if
-
+        !
         ! -- read connection number
         ival = this%parser%GetInteger()
         if (ival < 1 .or. ival > this%nlakeconn(n)) then
@@ -791,17 +766,17 @@ subroutine lak_read_lake_connections(this)
           call store_error(errmsg)
           cycle
         end if
-
+        !
         j = ival
         ipos = this%idxlakeconn(n) + ival - 1
-
+        !
         ! -- set imap
         this%imap(ipos) = n
-
+        !
         !
         ! -- increment nboundchk
         nboundchk(ipos) = nboundchk(ipos) + 1
-
+        !
         ! -- read gwfnodes from the line
         call this%parser%GetCellid(this%dis%ndim, cellid)
         nn = this%dis%noder_from_cellid(cellid, &
@@ -813,11 +788,11 @@ subroutine lak_read_lake_connections(this)
             'INVALID cellid FOR LAKE ', n, 'connection', j
           call store_error(errmsg)
         end if
-
+        !
         ! -- set gwf cellid for connection
         this%cellid(ipos) = nn
         this%nodesontop(ipos) = nn
-
+        !
         ! -- read ictype
         call this%parser%GetStringCaps(keyword)
         select case (keyword)
@@ -836,28 +811,47 @@ subroutine lak_read_lake_connections(this)
           call store_error(errmsg)
         end select
         write (ctypenm, '(a16)') keyword
-
+        !
         ! -- bed leakance
-        !this%bedleak(ipos) = this%parser%GetDouble()
+        !this%bedleak(ipos) = this%parser%GetDouble() !TODO: use this when NONE keyword deprecated
         call this%parser%GetStringCaps(keyword)
         select case (keyword)
         case ('NONE')
-          this%bedleak(ipos) = -DONE
+          is_lake_bed = .FALSE.
+          this%bedleak(ipos) = DNODATA
+          !
+          ! -- create warning message
+          write (warnmsg, '(2(a,1x,i0,1x),a,1pe7.1,a)') &
+            'BEDLEAK for connection', j, 'in lake', n, 'is specified to '// &
+            'be NONE. Lake connections where the lake-GWF connection '// &
+            'conductance is solely a function of aquifer properties '// &
+            'in the connected GWF cell should be specified with a '// &
+            'DNODATA (', DNODATA, ') value.'
+          !
+          ! -- create deprecation warning
+          call deprecation_warning('CONNECTIONDATA', 'bedleak=NONE', '6.5.0', &
+                                   warnmsg, this%parser%GetUnit())
         case default
-          read (keyword, *) this%bedleak(ipos)
+          read (keyword, *) rval
+          if (is_close(rval, DNODATA)) then
+            is_lake_bed = .FALSE.
+          else
+            is_lake_bed = .TRUE.
+          end if
+          this%bedleak(ipos) = rval
         end select
-
-        if (keyword /= 'NONE' .and. this%bedleak(ipos) < dzero) then
+        !
+        if (is_lake_bed .and. this%bedleak(ipos) < DZERO) then
           write (errmsg, '(a,1x,i0,1x,a)') 'bedleak FOR LAKE ', n, 'MUST BE >= 0'
           call store_error(errmsg)
         end if
-
+        !
         ! -- belev
         this%belev(ipos) = this%parser%GetDouble()
-
+        !
         ! -- telev
         this%telev(ipos) = this%parser%GetDouble()
-
+        !
         ! -- connection length
         rval = this%parser%GetDouble()
         if (rval <= DZERO) then
@@ -873,7 +867,7 @@ subroutine lak_read_lake_connections(this)
           end if
         end if
         this%connlength(ipos) = rval
-
+        !
         ! -- connection width
         rval = this%parser%GetDouble()
         if (rval < dzero) then
@@ -1009,17 +1003,13 @@ subroutine lak_read_lake_connections(this)
       call this%parser%StoreErrorUnit()
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_read_lake_connections
 
+  !> @brief Read the lake tables for this package
+  !<
   subroutine lak_read_tables(this)
-! ******************************************************************************
-! lak_read_tables -- Read the lake tables for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error, count_errors
     ! -- dummy
@@ -1029,16 +1019,11 @@ subroutine lak_read_tables(this)
     character(len=LINELENGTH) :: line
     character(len=LINELENGTH) :: keyword
     integer(I4B) :: ierr
-    logical :: isfound, endOfBlock
+    logical(LGP) :: isfound, endOfBlock
     integer(I4B) :: n
     integer(I4B) :: iconn
     integer(I4B) :: ntabs
     integer(I4B), dimension(:), pointer, contiguous :: nboundchk
-! ------------------------------------------------------------------------------
-
-    ! -- format
-    !
-    ! -- code
     !
     ! -- skip of no outlets
     if (this%ntables < 1) return
@@ -1066,17 +1051,17 @@ subroutine lak_read_tables(this)
         call this%parser%GetNextLine(endOfBlock)
         if (endOfBlock) exit
         n = this%parser%GetInteger()
-
+        !
         if (n < 1 .or. n > this%nlakes) then
           write (errmsg, '(a,1x,i0)') 'lakeno MUST BE > 0 and <= ', this%nlakes
           call store_error(errmsg)
           cycle readtable
         end if
-
+        !
         ! -- increment ntab and nboundchk
         ntabs = ntabs + 1
         nboundchk(n) = nboundchk(n) + 1
-
+        !
         ! -- read FILE keyword
         call this%parser%GetStringCaps(keyword)
         select case (keyword)
@@ -1097,7 +1082,7 @@ subroutine lak_read_tables(this)
           cycle readtable
         end select
       end do readtable
-
+      !
       write (this%iout, '(1x,a)') &
         'END OF '//trim(adjustl(this%text))//' LAKE_TABLES'
       !
@@ -1144,18 +1129,14 @@ subroutine lak_read_tables(this)
     end do
     deallocate (laketables)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_read_tables
 
+  !> @brief Copy the laketables structure data into flattened vectors that are
+  !! stored in the memory manager
+  !<
   subroutine laktables_to_vectors(this, laketables)
-! ******************************************************************************
-! laktables_to_vectors -- Copy the laketables structure data into flattened
-!   vectors that are stored in the memory manager
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     class(LakType), intent(inout) :: this
     type(LakTabType), intent(in), dimension(:), contiguous :: laketables
     integer(I4B) :: n
@@ -1163,7 +1144,6 @@ subroutine laktables_to_vectors(this, laketables)
     integer(I4B) :: j
     integer(I4B) :: ipos
     integer(I4B) :: iconn
-! ------------------------------------------------------------------------------
     !
     ! -- allocate index array for lak tables
     call mem_allocate(this%ialaktab, this%nlakes + 1, 'IALAKTAB', this%memoryPath)
@@ -1201,17 +1181,13 @@ subroutine laktables_to_vectors(this, laketables)
       end do
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine laktables_to_vectors
 
+  !> @brief Read the lake table for this package
+  !<
   subroutine lak_read_table(this, ilak, filename, laketable)
-! ******************************************************************************
-! lak_read_table -- Read the lake table for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use ConstantsModule, only: LINELENGTH
     use InputOutputModule, only: openfile
     use SimModule, only: store_error, count_errors
@@ -1223,7 +1199,7 @@ subroutine lak_read_table(this, ilak, filename, laketable)
     ! -- local
     character(len=LINELENGTH) :: keyword
     integer(I4B) :: ierr
-    logical :: isfound, endOfBlock
+    logical(LGP) :: isfound, endOfBlock
     integer(I4B) :: iu
     integer(I4B) :: n
     integer(I4B) :: ipos
@@ -1239,11 +1215,6 @@ subroutine lak_read_table(this, ilak, filename, laketable)
     ! -- formats
     character(len=*), parameter :: fmttaberr = &
       &'(a,1x,i0,1x,a,1x,g15.6,1x,a,1x,i0,1x,a,1x,i0,1x,a,1x,g15.6,1x,a)'
-! ------------------------------------------------------------------------------
-
-    ! -- format
-    !
-    ! -- code
     !
     ! -- initialize locals
     n = 0
@@ -1288,7 +1259,7 @@ subroutine lak_read_table(this, ilak, filename, laketable)
             write (errmsg, '(a,1x,i0)') 'LAKE TABLE NCOL MUST BE >= ', jmin
             call store_error(errmsg)
           end if
-
+          !
         case default
           write (errmsg, '(a,a)') &
             'UNKNOWN '//trim(this%text)//' DIMENSIONS KEYWORD: ', trim(keyword)
@@ -1328,13 +1299,13 @@ subroutine lak_read_table(this, ilak, filename, laketable)
       if (this%ictype(ipos) == 2 .or. this%ictype(ipos) == 3) then
         allocate (laketable%tabwarea(n))
       end if
-
+      !
       ! -- get table block
       call parser%GetBlock('TABLE', isfound, ierr, supportOpenClose=.true.)
       !
       ! -- parse well_connections block if detected
       if (isfound) then
-
+        !
         ! -- process the table data
         if (this%iprpak /= 0) then
           write (this%iout, '(/1x,a)') &
@@ -1356,7 +1327,7 @@ subroutine lak_read_table(this, ilak, filename, laketable)
             laketable%tabwarea(ipos) = parser%GetDouble()
           end if
         end do readtabledata
-
+        !
         if (this%iprpak /= 0) then
           write (this%iout, '(1x,a)') &
             'END OF '//trim(adjustl(this%text))//' TABLE'
@@ -1446,17 +1417,13 @@ subroutine lak_read_table(this, ilak, filename, laketable)
     ! Close the table file and clear other parser members
     call parser%Clear()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_read_table
 
+  !> @brief Read the lake outlets for this package
+  !<
   subroutine lak_read_outlets(this)
-! ******************************************************************************
-! lak_read_outlets -- Read the lake outlets for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error, count_errors
     use TimeSeriesManagerModule, only: read_value_or_time_series_adv
@@ -1467,16 +1434,11 @@ subroutine lak_read_outlets(this)
     character(len=LENBOUNDNAME) :: bndName
     character(len=9) :: citem
     integer(I4B) :: ierr, ival
-    logical :: isfound, endOfBlock
+    logical(LGP) :: isfound, endOfBlock
     integer(I4B) :: n
     integer(I4B) :: jj
     integer(I4B), dimension(:), pointer, contiguous :: nboundchk
     real(DP), pointer :: bndElem => null()
-    !
-    ! -- format
-    !
-    ! -- code
-! ------------------------------------------------------------------------------
     !
     ! -- get well_connections block
     call this%parser%GetBlock('OUTLETS', isfound, ierr, &
@@ -1513,7 +1475,7 @@ subroutine lak_read_outlets(this)
         do n = 1, this%noutlets
           this%outrate(n) = DZERO
         end do
-
+        !
         ! -- process the lake connection data
         write (this%iout, '(/1x,a)') &
           'PROCESSING '//trim(adjustl(this%text))//' OUTLETS'
@@ -1541,7 +1503,7 @@ subroutine lak_read_outlets(this)
             cycle readoutlet
           end if
           this%lakein(n) = ival
-
+          !
           ! -- read outlet lakeout
           ival = this%parser%GetInteger()
           if (ival < 0 .or. ival > this%nlakes) then
@@ -1551,7 +1513,7 @@ subroutine lak_read_outlets(this)
             cycle readoutlet
           end if
           this%lakeout(n) = ival
-
+          !
           ! -- read ictype
           call this%parser%GetStringCaps(keyword)
           select case (keyword)
@@ -1567,11 +1529,11 @@ subroutine lak_read_outlets(this)
             call store_error(errmsg)
             cycle readoutlet
           end select
-
+          !
           ! -- build bndname for outlet
           write (citem, '(i9.9)') n
           bndName = 'OUTLET'//citem
-
+          !
           ! -- set a few variables for timeseries aware variables
           jj = 1
           !
@@ -1627,7 +1589,7 @@ subroutine lak_read_outlets(this)
           'SPECIFIED OR IS SPECIFIED TO BE 0.'
         call store_error(errmsg)
       end if
-
+      !
     else
       if (this%noutlets > 0) then
         call store_error('REQUIRED OUTLETS BLOCK NOT FOUND.')
@@ -1640,17 +1602,13 @@ subroutine lak_read_outlets(this)
       call this%parser%StoreErrorUnit()
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_read_outlets
 
+  !> @brief Read the dimensions for this package
+  !<
   subroutine lak_read_dimensions(this)
-! ******************************************************************************
-! pak1read_dimensions -- Read the dimensions for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error, count_errors
     ! -- dummy
@@ -1658,9 +1616,7 @@ subroutine lak_read_dimensions(this)
     ! -- local
     character(len=LINELENGTH) :: keyword
     integer(I4B) :: ierr
-    logical :: isfound, endOfBlock
-    ! -- format
-! ------------------------------------------------------------------------------
+    logical(LGP) :: isfound, endOfBlock
     !
     ! -- initialize dimensions to -1
     this%nlakes = -1
@@ -1699,7 +1655,7 @@ subroutine lak_read_dimensions(this)
     else
       call store_error('REQUIRED DIMENSIONS BLOCK NOT FOUND.')
     end if
-
+    !
     if (this%nlakes < 0) then
       write (errmsg, '(a)') &
         'NLAKES WAS NOT SPECIFIED OR WAS SPECIFIED INCORRECTLY.'
@@ -1733,17 +1689,13 @@ subroutine lak_read_dimensions(this)
     ! -- setup the stage table object
     call this%lak_setup_tableobj()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_read_dimensions
 
+  !> @brief Read the initial parameters for this package
+  !<
   subroutine lak_read_initial_attr(this)
-! ******************************************************************************
-! pak1read_dimensions -- Read the initial parameters for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use ConstantsModule, only: LINELENGTH
     use MemoryHelperModule, only: create_mem_path
     use SimModule, only: store_error, count_errors
@@ -1780,8 +1732,6 @@ subroutine lak_read_initial_attr(this)
     data ctype(1)/'HORIZONTAL'/
     data ctype(2)/'EMBEDDEDH '/
     data ctype(3)/'EMBEDDEDV '/
-    ! -- format
-! ------------------------------------------------------------------------------
     !
     ! -- initialize xnewpak and set stage
     do n = 1, this%nlakes
@@ -1827,7 +1777,7 @@ subroutine lak_read_initial_attr(this)
     ! -- allocate temporary storage
     allocate (clb(this%MAXBOUND))
     allocate (caq(this%MAXBOUND))
-
+    !
     ! -- calculate saturated conductance for each connection
     do n = 1, this%nlakes
       do j = this%idxlakeconn(n), this%idxlakeconn(n + 1) - 1
@@ -1882,10 +1832,10 @@ subroutine lak_read_initial_attr(this)
           end if
           length = this%connlength(j)
         end if
-        if (this%bedleak(j) < DZERO) then
-          clb(j) = -DONE
+        if (is_close(this%bedleak(j), DNODATA)) then
+          clb(j) = DNODATA
         else if (this%bedleak(j) > DZERO) then
-          clb(j) = done / this%bedleak(j)
+          clb(j) = DONE / this%bedleak(j)
         else
           clb(j) = DZERO
         end if
@@ -1894,7 +1844,7 @@ subroutine lak_read_initial_attr(this)
         else
           caq(j) = DZERO
         end if
-        if (this%bedleak(j) < DZERO) then
+        if (is_close(this%bedleak(j), DNODATA)) then
           this%satcond(j) = area / caq(j)
         else if (clb(j) * caq(j) > DZERO) then
           this%satcond(j) = area / (clb(j) + caq(j))
@@ -1929,7 +1879,7 @@ subroutine lak_read_initial_attr(this)
           nn = this%cellid(j)
           area = this%warea(j)
           c1 = DZERO
-          if (clb(j) < DZERO) then
+          if (is_close(clb(j), DNODATA)) then
             cbedleak = '     NONE     '
             cbedcond = '     NONE     '
           else if (clb(j) > DZERO) then
@@ -1961,7 +1911,7 @@ subroutine lak_read_initial_attr(this)
       write (this%iout, '(1x,a)') &
         'IF EMBEDDED CONNECTION, CONDUCTANCES ARE PER &
         &UNIT EXCHANGE AREA (1/T).'
-
+      !
       !        write(this%iout,*) n, idx, nodestr, this%sarea(j), this%warea(j)
       !
       ! -- calculate stage, surface area, wetted area, volume relation
@@ -1982,7 +1932,7 @@ subroutine lak_read_initial_attr(this)
           s = s + dx
         end do
         write (this%iout, "(1x,70('-'))")
-
+        !
         write (this%iout, '(//1x,a,1x,i10)') 'STAGE/VOLUME RELATION FOR LAKE  ', n
         write (this%iout, '(/1x,4(a14))') '              ', '              ', &
     &                                    '    CALCULATED', '         STAGE'
@@ -2010,12 +1960,14 @@ subroutine lak_read_initial_attr(this)
     deallocate (clb)
     deallocate (caq)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_read_initial_attr
 
-! -- simple subroutine for linear interpolation of two vectors
-!       function assumes x data is sorted in ascending order
+  !> @brief Perform linear interpolation of two vectors.
+  !!
+  !! Function assumes x data is sorted in ascending order
+  !<
   subroutine lak_linear_interpolation(this, n, x, y, z, v)
     ! -- dummy
     class(LakType), intent(inout) :: this
@@ -2057,17 +2009,14 @@ subroutine lak_linear_interpolation(this, n, x, y, z, v)
         end if
       end do
     end if
-    ! return
+    !
+    ! -- Return
     return
   end subroutine lak_linear_interpolation
 
+  !> @brief Calculate the surface area of a lake at a given stage
+  !<
   subroutine lak_calculate_sarea(this, ilak, stage, sarea)
-! ******************************************************************************
-! lak_calculate_sarea -- Calculate the surface area of a lake at a given stage.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
@@ -2081,8 +2030,7 @@ subroutine lak_calculate_sarea(this, ilak, stage, sarea)
     real(DP) :: botl
     real(DP) :: sat
     real(DP) :: sa
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     sarea = DZERO
     i = this%ntabrow(ilak)
     if (i > 0) then
@@ -2107,17 +2055,13 @@ subroutine lak_calculate_sarea(this, ilak, stage, sarea)
       end do
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_sarea
 
+  !> @brief Calculate the wetted area of a lake at a given stage.
+  !<
   subroutine lak_calculate_warea(this, ilak, stage, warea, hin)
-! ******************************************************************************
-! lak_calculate_warea -- Calculate the wetted area of a lake at a given stage.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
@@ -2129,8 +2073,7 @@ subroutine lak_calculate_warea(this, ilak, stage, warea, hin)
     integer(I4B) :: igwfnode
     real(DP) :: head
     real(DP) :: wa
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     warea = DZERO
     do i = this%idxlakeconn(ilak), this%idxlakeconn(ilak + 1) - 1
       if (present(hin)) then
@@ -2143,18 +2086,13 @@ subroutine lak_calculate_warea(this, ilak, stage, warea, hin)
       warea = warea + wa
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_warea
 
+  !> @brief Calculate the wetted area of a lake connection at a given stage
+  !<
   subroutine lak_calculate_conn_warea(this, ilak, iconn, stage, head, wa)
-! ******************************************************************************
-! lak_calculate_conn_warea -- Calculate the wetted area of a lake connection
-!                             at a given stage.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
@@ -2171,8 +2109,7 @@ subroutine lak_calculate_conn_warea(this, ilak, iconn, stage, head, wa)
     real(DP) :: botl
     real(DP) :: vv
     real(DP) :: sat
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     wa = DZERO
     topl = this%telev(iconn)
     botl = this%belev(iconn)
@@ -2203,17 +2140,13 @@ subroutine lak_calculate_conn_warea(this, ilak, iconn, stage, head, wa)
       wa = sat * this%warea(iconn)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_conn_warea
 
+  !> @brief Calculate the volume of a lake at a given stage
+  !<
   subroutine lak_calculate_vol(this, ilak, stage, volume)
-! ******************************************************************************
-! lak_calculate_vol -- Calculate the volume of a lake at a given stage.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
@@ -2229,8 +2162,7 @@ subroutine lak_calculate_vol(this, ilak, stage, volume)
     real(DP) :: sa
     real(DP) :: v
     real(DP) :: sat
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     volume = DZERO
     i = this%ntabrow(ilak)
     if (i > 0) then
@@ -2264,18 +2196,13 @@ subroutine lak_calculate_vol(this, ilak, stage, volume)
       end do
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_vol
 
+  !> @brief Calculate the total conductance for a lake at a provided stage
+  !<
   subroutine lak_calculate_conductance(this, ilak, stage, conductance)
-! ******************************************************************************
-! lak_calculate_conductance -- Calculate the total conductance for a lake at a
-!                              provided stage.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
@@ -2284,28 +2211,22 @@ subroutine lak_calculate_conductance(this, ilak, stage, conductance)
     ! -- local
     integer(I4B) :: i
     real(DP) :: c
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     conductance = DZERO
     do i = this%idxlakeconn(ilak), this%idxlakeconn(ilak + 1) - 1
       call this%lak_calculate_conn_conductance(ilak, i, stage, stage, c)
       conductance = conductance + c
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_conductance
 
+  !> @brief Calculate the controlling lake stage or groundwater head used to
+  !! calculate the conductance for a lake connection from a provided stage and
+  !! groundwater head
+  !<
   subroutine lak_calculate_cond_head(this, iconn, stage, head, vv)
-! ******************************************************************************
-! lak_calculate_conn_head -- Calculate the controlling lake stage or groundwater
-!                            head used to calculate the conductance for a lake
-!                            connection from a provided stage and groundwater
-!                            head.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: iconn
@@ -2317,8 +2238,7 @@ subroutine lak_calculate_cond_head(this, iconn, stage, head, vv)
     real(DP) :: hh
     real(DP) :: topl
     real(DP) :: botl
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     topl = this%telev(iconn)
     botl = this%belev(iconn)
     ss = min(stage, topl)
@@ -2331,19 +2251,14 @@ subroutine lak_calculate_cond_head(this, iconn, stage, head, vv)
       vv = DHALF * (ss + hh)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_cond_head
 
+  !> @brief Calculate the conductance for a lake connection at a provided stage
+  !! and groundwater head
+  !<
   subroutine lak_calculate_conn_conductance(this, ilak, iconn, stage, head, cond)
-! ******************************************************************************
-! lak_calculate_conn_conductance -- Calculate the conductance for a lake
-!                                   connection at a provided stage
-!                                   and groundwater head.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
@@ -2361,8 +2276,7 @@ subroutine lak_calculate_conn_conductance(this, ilak, iconn, stage, head, cond)
     real(DP) :: sat
     real(DP) :: wa
     real(DP) :: vscratio
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     cond = DZERO
     vscratio = DONE
     topl = this%telev(iconn)
@@ -2407,18 +2321,13 @@ subroutine lak_calculate_conn_conductance(this, ilak, iconn, stage, head, cond)
     end if
     cond = sat * this%satcond(iconn) * vscratio
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_conn_conductance
 
+  !> @brief Calculate the total groundwater-lake flow at a provided stage
+  !<
   subroutine lak_calculate_exchange(this, ilak, stage, totflow)
-! ******************************************************************************
-! lak_calculate_exchange -- Calculate the total groundwater-lake flow at a
-!                           provided stage.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
@@ -2429,8 +2338,7 @@ subroutine lak_calculate_exchange(this, ilak, stage, totflow)
     integer(I4B) :: igwfnode
     real(DP) :: flow
     real(DP) :: hgwf
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     totflow = DZERO
     do j = this%idxlakeconn(ilak), this%idxlakeconn(ilak + 1) - 1
       igwfnode = this%cellid(j)
@@ -2439,19 +2347,15 @@ subroutine lak_calculate_exchange(this, ilak, stage, totflow)
       totflow = totflow + flow
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_exchange
 
+  !> @brief Calculate the groundwater-lake flow at a provided stage and
+  !! groundwater head
+  !<
   subroutine lak_calculate_conn_exchange(this, ilak, iconn, stage, head, flow, &
                                          gwfhcof, gwfrhs)
-! ******************************************************************************
-! lak_calculate_conn_exchange -- Calculate the groundwater-lake flow at a
-!                                provided stage and groundwater head.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
@@ -2468,8 +2372,7 @@ subroutine lak_calculate_conn_exchange(this, ilak, iconn, stage, head, flow, &
     real(DP) :: hh
     real(DP) :: gwfhcof0
     real(DP) :: gwfrhs0
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     flow = DZERO
     call this%lak_calculate_conn_conductance(ilak, iconn, stage, head, cond)
     botl = this%belev(iconn)
@@ -2510,19 +2413,15 @@ subroutine lak_calculate_conn_exchange(this, ilak, iconn, stage, head, flow, &
     if (present(gwfhcof)) gwfhcof = gwfhcof0
     if (present(gwfrhs)) gwfrhs = gwfrhs0
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_conn_exchange
 
+  !> @brief Calculate the groundwater-lake flow at a provided stage and
+  !! groundwater head
+  !<
   subroutine lak_estimate_conn_exchange(this, iflag, ilak, iconn, idry, stage, &
                                         head, flow, source, gwfhcof, gwfrhs)
-! ******************************************************************************
-! lak_estimate_conn_exchange -- Calculate the groundwater-lake flow at a
-!                               provided stage and groundwater head.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: iflag
@@ -2537,8 +2436,7 @@ subroutine lak_estimate_conn_exchange(this, iflag, ilak, iconn, idry, stage, &
     real(DP), intent(inout), optional :: gwfrhs
     ! -- local
     real(DP) :: gwfhcof0, gwfrhs0
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     flow = DZERO
     idry = 0
     call this%lak_calculate_conn_exchange(ilak, iconn, stage, head, flow, &
@@ -2561,18 +2459,14 @@ subroutine lak_estimate_conn_exchange(this, iflag, ilak, iconn, idry, stage, &
     if (present(gwfhcof)) gwfhcof = gwfhcof0
     if (present(gwfrhs)) gwfrhs = gwfrhs0
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_estimate_conn_exchange
 
+  !> @brief Calculate the storage change in a lake based on provided stages
+  !! and a passed delt
+  !<
   subroutine lak_calculate_storagechange(this, ilak, stage, stage0, delt, dvr)
-! ******************************************************************************
-! lak_calculate_storagechange -- Calculate the storage change in a lake based on
-!                         provided stages and a passed delt.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
@@ -2583,8 +2477,7 @@ subroutine lak_calculate_storagechange(this, ilak, stage, stage0, delt, dvr)
     ! -- local
     real(DP) :: v
     real(DP) :: v0
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     dvr = DZERO
     if (this%gwfiss /= 1) then
       call this%lak_calculate_vol(ilak, stage, v)
@@ -2592,17 +2485,13 @@ subroutine lak_calculate_storagechange(this, ilak, stage, stage0, delt, dvr)
       dvr = (v0 - v) / delt
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_storagechange
 
+  !> @brief Calculate the rainfall for a lake
+  !<
   subroutine lak_calculate_rainfall(this, ilak, stage, ra)
-! ******************************************************************************
-! lak_calculate_rainfall -- Calculate the rainfall for a lake .
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
@@ -2611,8 +2500,7 @@ subroutine lak_calculate_rainfall(this, ilak, stage, ra)
     ! -- local
     integer(I4B) :: iconn
     real(DP) :: sa
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     ! -- rainfall
     iconn = this%idxlakeconn(ilak)
     if (this%ictype(iconn) == 2 .or. this%ictype(iconn) == 3) then
@@ -2622,64 +2510,47 @@ subroutine lak_calculate_rainfall(this, ilak, stage, ra)
     end if
     ra = this%rainfall(ilak) * sa
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_rainfall
 
+  !> @brief Calculate runoff to a lake
+  !<
   subroutine lak_calculate_runoff(this, ilak, ro)
-! ******************************************************************************
-! lak_calculate_runoff -- Calculate runoff to a lake.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
     real(DP), intent(inout) :: ro
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     ! -- runoff
     ro = this%runoff(ilak)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_runoff
 
+  !> @brief Calculate specified inflow to a lake
+  !<
   subroutine lak_calculate_inflow(this, ilak, qin)
-! ******************************************************************************
-! lak_calculate_inflow -- Calculate specified inflow to a lake.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
     real(DP), intent(inout) :: qin
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     ! -- inflow to lake
     qin = this%inflow(ilak)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_inflow
 
+  !> @brief Calculate the external flow terms to a lake
+  !<
   subroutine lak_calculate_external(this, ilak, ex)
-! ******************************************************************************
-! lak_calculate_external -- Calculate the external flow terms to a lake.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
     real(DP), intent(inout) :: ex
-    ! -- local
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- If mover is active, add receiver water to rhs and
     !    store available water (as positive value)
@@ -2688,26 +2559,19 @@ subroutine lak_calculate_external(this, ilak, ex)
       ex = this%pakmvrobj%get_qfrommvr(ilak)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_external
 
+  !> @brief Calculate the withdrawal from a lake subject to an available volume
+  !<
   subroutine lak_calculate_withdrawal(this, ilak, avail, wr)
-! ******************************************************************************
-! lak_calculate_withdrawal -- Calculate the withdrawal from a lake subject to
-!                             an available volume.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
     real(DP), intent(inout) :: avail
     real(DP), intent(inout) :: wr
-    ! -- local
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     ! -- withdrawals - limit to sum of inflows and available volume
     wr = this%withdrawal(ilak)
     if (wr > avail) then
@@ -2719,18 +2583,14 @@ subroutine lak_calculate_withdrawal(this, ilak, avail, wr)
     end if
     avail = avail + wr
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_withdrawal
 
+  !> @brief Calculate the evaporation from a lake at a provided stage subject
+  !! to an available volume
+  !<
   subroutine lak_calculate_evaporation(this, ilak, stage, avail, ev)
-! ******************************************************************************
-! lak_calculate_evaporation -- Calculate the evaporation from a lake at a
-!                              provided stage subject to an available volume.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
@@ -2739,13 +2599,12 @@ subroutine lak_calculate_evaporation(this, ilak, stage, avail, ev)
     real(DP), intent(inout) :: ev
     ! -- local
     real(DP) :: sa
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     ! -- evaporation - limit to sum of inflows and available volume
     call this%lak_calculate_sarea(ilak, stage, sa)
     ev = sa * this%evaporation(ilak)
     if (ev > avail) then
-      if (is_same(avail, DPREC)) then
+      if (is_close(avail, DPREC)) then
         ev = DZERO
       else
         ev = -avail
@@ -2755,25 +2614,19 @@ subroutine lak_calculate_evaporation(this, ilak, stage, avail, ev)
     end if
     avail = avail + ev
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_evaporation
 
+  !> @brief Calculate the outlet inflow to a lake
+  !<
   subroutine lak_calculate_outlet_inflow(this, ilak, outinf)
-! ******************************************************************************
-! lak_calculate_outlet_inflow -- Calculate the outlet inflow to a lake.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
     real(DP), intent(inout) :: outinf
     ! -- local
     integer(I4B) :: n
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     outinf = DZERO
     do n = 1, this%noutlets
@@ -2785,17 +2638,13 @@ subroutine lak_calculate_outlet_inflow(this, ilak, outinf)
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_outlet_inflow
 
+  !> @brief Calculate the outlet outflow from a lake
+  !<
   subroutine lak_calculate_outlet_outflow(this, ilak, stage, avail, outoutf)
-! ******************************************************************************
-! lak_calculate_outlet_outflow -- Calculate the outlet outflow from a lake.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
@@ -2809,8 +2658,6 @@ subroutine lak_calculate_outlet_outflow(this, ilak, stage, avail, outoutf)
     real(DP) :: c
     real(DP) :: gsm
     real(DP) :: rate
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     outoutf = DZERO
     do n = 1, this%noutlets
@@ -2852,25 +2699,20 @@ subroutine lak_calculate_outlet_outflow(this, ilak, stage, avail, outoutf)
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_outlet_outflow
 
+  !> @brief Get the outlet inflow to a lake from another lake
+  !<
   subroutine lak_get_internal_inlet(this, ilak, outinf)
-! ******************************************************************************
-! lak_get_internal_inlet -- Get the outlet inflow to a lake from another lake.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
     real(DP), intent(inout) :: outinf
     ! -- local
     integer(I4B) :: n
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     outinf = DZERO
     do n = 1, this%noutlets
       if (this%lakeout(n) == ilak) then
@@ -2881,25 +2723,20 @@ subroutine lak_get_internal_inlet(this, ilak, outinf)
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_get_internal_inlet
 
+  !> @brief Get the outlet from a lake to another lake
+  !<
   subroutine lak_get_internal_outlet(this, ilak, outoutf)
-! ******************************************************************************
-! lak_get_internal_outlet -- Get the outlet from a lake to another lake.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
     real(DP), intent(inout) :: outoutf
     ! -- local
     integer(I4B) :: n
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     outoutf = DZERO
     do n = 1, this%noutlets
       if (this%lakein(n) == ilak) then
@@ -2908,26 +2745,20 @@ subroutine lak_get_internal_outlet(this, ilak, outoutf)
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_get_internal_outlet
 
+  !> @brief Get the outlet outflow from a lake to an external boundary
+  !<
   subroutine lak_get_external_outlet(this, ilak, outoutf)
-! ******************************************************************************
-! lak_get_external_outlet -- Get the outlet outflow from a lake to an external
-!                            boundary.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
     real(DP), intent(inout) :: outoutf
     ! -- local
     integer(I4B) :: n
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     outoutf = DZERO
     do n = 1, this%noutlets
       if (this%lakein(n) == ilak) then
@@ -2936,26 +2767,20 @@ subroutine lak_get_external_outlet(this, ilak, outoutf)
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_get_external_outlet
 
+  !> @brief Get the mover outflow from a lake to an external boundary
+  !<
   subroutine lak_get_external_mover(this, ilak, outoutf)
-! ******************************************************************************
-! lak_get_external_mover -- Get the mover outflow from a lake to an external
-!                           boundary.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
     real(DP), intent(inout) :: outoutf
     ! -- local
     integer(I4B) :: n
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     outoutf = DZERO
     if (this%imover == 1) then
       do n = 1, this%noutlets
@@ -2966,25 +2791,20 @@ subroutine lak_get_external_mover(this, ilak, outoutf)
       end do
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_get_external_mover
 
+  !> @brief Get the mover outflow from a lake to another lake
+  !<
   subroutine lak_get_internal_mover(this, ilak, outoutf)
-! ******************************************************************************
-! lak_get_internal_mover -- Get the mover outflow from a lake to another lake.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
     real(DP), intent(inout) :: outoutf
     ! -- local
     integer(I4B) :: n
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     outoutf = DZERO
     if (this%imover == 1) then
       do n = 1, this%noutlets
@@ -2995,25 +2815,20 @@ subroutine lak_get_internal_mover(this, ilak, outoutf)
       end do
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_get_internal_mover
 
+  !> @brief Get the outlet to mover from a lake
+  !<
   subroutine lak_get_outlet_tomover(this, ilak, outoutf)
-! ******************************************************************************
-! lak_get_outlet_tomover -- Get the outlet to mover from a lake.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
     real(DP), intent(inout) :: outoutf
     ! -- local
     integer(I4B) :: n
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     outoutf = DZERO
     if (this%imover == 1) then
       do n = 1, this%noutlets
@@ -3023,17 +2838,13 @@ subroutine lak_get_outlet_tomover(this, ilak, outoutf)
       end do
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_get_outlet_tomover
 
+  !> @brief Determine the stage from a provided volume
+  !<
   subroutine lak_vol2stage(this, ilak, vol, stage)
-! ******************************************************************************
-! lak_vol2stage-- Determine the stage from a provided volume.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
@@ -3049,8 +2860,7 @@ subroutine lak_vol2stage(this, ilak, vol, stage)
     real(DP) :: en0, en1
     real(DP) :: ds, ds0
     real(DP) :: denom
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     s0 = this%lakebot(ilak)
     call this%lak_calculate_vol(ilak, s0, v0)
     s1 = this%laketop(ilak)
@@ -3113,15 +2923,13 @@ subroutine lak_vol2stage(this, ilak, vol, stage)
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_vol2stage
 
+  !> @brief Determine if a valid lake or outlet number has been specified
   function lak_check_valid(this, itemno) result(ierr)
-! ******************************************************************************
-!  lak_check_valid -- Determine if a valid lake or outlet number has been
-!                     specified.
-! ******************************************************************************
+    ! -- modules
     use SimModule, only: store_error
     ! -- return
     integer(I4B) :: ierr
@@ -3130,8 +2938,7 @@ function lak_check_valid(this, itemno) result(ierr)
     integer(I4B), intent(in) :: itemno
     ! -- local
     integer(I4B) :: ival
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     ierr = 0
     ival = abs(itemno)
     if (itemno > 0) then
@@ -3151,16 +2958,15 @@ function lak_check_valid(this, itemno) result(ierr)
         ierr = 1
       end if
     end if
+    !
+    ! -- Return
+    return
   end function lak_check_valid
 
+  !> @brief Set a stress period attribute for lakweslls(itemno) using keywords
+  !<
   subroutine lak_set_stressperiod(this, itemno)
-! ******************************************************************************
-! lak_set_stressperiod -- Set a stress period attribute for lakweslls(itemno)
-!                         using keywords.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use TimeSeriesManagerModule, only: read_value_or_time_series_adv
     use SimModule, only: store_error
     ! -- dummy
@@ -3174,8 +2980,6 @@ subroutine lak_set_stressperiod(this, itemno)
     integer(I4B) :: ii
     integer(I4B) :: jj
     real(DP), pointer :: bndElem => null()
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- read line
     call this%parser%GetStringCaps(keyword)
@@ -3372,28 +3176,23 @@ subroutine lak_set_stressperiod(this, itemno)
         trim(keyword)//'.'
     end select
     !
-    ! -- return
+    ! -- Return
 999 return
   end subroutine lak_set_stressperiod
 
+  !> @brief Issue a parameter error for lakweslls(ilak)
+  !!
+  !! Read itmp and new boundaries if itmp > 0
+  !<
   subroutine lak_set_attribute_error(this, ilak, keyword, msg)
-! ******************************************************************************
-! lak_set_attribute_error -- Issue a parameter error for lakweslls(ilak)
-! Subroutine: (1) read itmp
-!             (2) read new boundaries if itmp>0
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use SimModule, only: store_error
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: ilak
     character(len=*), intent(in) :: keyword
     character(len=*), intent(in) :: msg
-    ! -- local
-    ! -- formats
-! ------------------------------------------------------------------------------
+    !
     if (len(msg) == 0) then
       write (errmsg, '(a,1x,a,1x,i0,1x,a)') &
         keyword, ' for LAKE', ilak, 'has already been set.'
@@ -3401,19 +3200,16 @@ subroutine lak_set_attribute_error(this, ilak, keyword, msg)
       write (errmsg, '(a,1x,a,1x,i0,1x,a)') keyword, ' for LAKE', ilak, msg
     end if
     call store_error(errmsg)
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_set_attribute_error
 
+  !> @brief Set options specific to LakType
+  !!
+  !! lak_options overrides BndType%bnd_options
+  !<
   subroutine lak_options(this, option, found)
-! ******************************************************************************
-! lak_options -- set options specific to LakType
-!
-! lak_options overrides BndType%bnd_options
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use ConstantsModule, only: MAXCHARLEN, DZERO, MNORMAL
     use OpenSpecModule, only: access, form
     use SimModule, only: store_error
@@ -3421,7 +3217,7 @@ subroutine lak_options(this, option, found)
     ! -- dummy
     class(LakType), intent(inout) :: this
     character(len=*), intent(inout) :: option
-    logical, intent(inout) :: found
+    logical(LGP), intent(inout) :: found
     ! -- local
     character(len=MAXCHARLEN) :: fname, keyword
     real(DP) :: r
@@ -3441,7 +3237,6 @@ subroutine lak_options(this, option, found)
       &"(4x, 'MAXIMUM LAK ITERATION VALUE (',i0,') SPECIFIED.')"
     character(len=*), parameter :: fmtdmaxchg = &
       &"(4x, 'MAXIMUM STAGE CHANGE VALUE (',g0,') SPECIFIED.')"
-! ------------------------------------------------------------------------------
     !
     found = .true.
     select case (option)
@@ -3564,24 +3359,17 @@ subroutine lak_options(this, option, found)
       found = .false.
     end select
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_options
 
+  !> @brief Allocate and Read
+  !!
+  !! Create new LAK package and point bndobj to the new package
+  !<
   subroutine lak_ar(this)
-    ! ******************************************************************************
-    ! lak_ar -- Allocate and Read
-    ! Subroutine: (1) create new-style package
-    !             (2) point bndobj to the new package
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
-    ! -- local
-    ! -- format
-    ! ------------------------------------------------------------------------------
     !
     call this%obs%obs_ar()
     !
@@ -3597,19 +3385,16 @@ subroutine lak_ar(this)
       call this%pakmvrobj%ar(this%noutlets, this%nlakes, this%memoryPath)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_ar
 
+  !> @brief Read and Prepare
+  !!
+  !! Read itmp and read new boundaries if itmp > 0
+  !<
   subroutine lak_rp(this)
-! ******************************************************************************
-! lak_rp -- Read and Prepare
-! Subroutine: (1) read itmp
-!             (2) read new boundaries if itmp>0
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use ConstantsModule, only: LINELENGTH
     use TdisModule, only: kper, nper
     use SimModule, only: store_error, count_errors
@@ -3619,8 +3404,8 @@ subroutine lak_rp(this)
     character(len=LINELENGTH) :: title
     character(len=LINELENGTH) :: line
     character(len=LINELENGTH) :: text
-    logical :: isfound
-    logical :: endOfBlock
+    logical(LGP) :: isfound
+    logical(LGP) :: endOfBlock
     integer(I4B) :: ierr
     integer(I4B) :: node
     integer(I4B) :: n
@@ -3631,7 +3416,6 @@ subroutine lak_rp(this)
       &"('Looking for BEGIN PERIOD iper.  Found ', a, ' instead.')"
     character(len=*), parameter :: fmtlsp = &
       &"(1X,/1X,'REUSING ',A,'S FROM LAST STRESS PERIOD')"
-! ------------------------------------------------------------------------------
     !
     ! -- set nbound to maxbound
     this%nbound = this%maxbound
@@ -3707,7 +3491,7 @@ subroutine lak_rp(this)
           call this%inputtab%line_to_columns(line)
         end if
       end do stressperiod
-
+      !
       if (this%iprpak /= 0) then
         call this%inputtab%finalize_table()
       end if
@@ -3740,17 +3524,13 @@ subroutine lak_rp(this)
       end do
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_rp
 
+  !> @brief Add package connection to matrix
+  !<
   subroutine lak_ad(this)
-! ******************************************************************************
-! lak_ad -- Add package connection to matrix
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SimVariablesModule, only: iFailedStepRetry
     ! -- dummy
@@ -3759,7 +3539,6 @@ subroutine lak_ad(this)
     integer(I4B) :: n
     integer(I4B) :: j
     integer(I4B) :: iaux
-! ------------------------------------------------------------------------------
     !
     ! -- Advance the time series
     call this%TsManager%ad()
@@ -3815,30 +3594,23 @@ subroutine lak_ad(this)
     !    "current" value.
     call this%obs%obs_ad()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_ad
 
-  subroutine lak_cf(this, reset_mover)
-    ! ******************************************************************************
-    ! lak_cf -- Formulate the HCOF and RHS terms
-    ! Subroutine: (1) skip if no lakes
-    !             (2) calculate hcof and rhs
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
+  !> @brief Formulate the HCOF and RHS terms
+  !!
+  !! Skip if no lakes, otherwise calculate hcof and rhs
+  !<
+  subroutine lak_cf(this)
     ! -- dummy
     class(LakType) :: this
-    logical, intent(in), optional :: reset_mover
     ! -- local
     integer(I4B) :: j, n
     integer(I4B) :: igwfnode
     real(DP) :: hlak, blak
-    logical :: lrm
-    ! ------------------------------------------------------------------------------
-    !!
-    !! -- Calculate lak conductance and update package RHS and HCOF
+    !
+    ! -- Calculate lak conductance and update package RHS and HCOF
     !call this%lak_cfupdate()
     !
     ! -- save groundwater seepage for lake solution
@@ -3852,13 +3624,6 @@ subroutine lak_cf(this, reset_mover)
       call this%lak_calculate_exchange(n, this%s0(n), this%qgwf0(n))
     end do
     !
-    ! -- pakmvrobj cf
-    lrm = .true.
-    if (present(reset_mover)) lrm = reset_mover
-    if (this%imover == 1 .and. lrm) then
-      call this%pakmvrobj%cf()
-    end if
-    !
     ! -- find highest active cell
     do n = 1, this%nlakes
       do j = this%idxlakeconn(n), this%idxlakeconn(n + 1) - 1
@@ -3911,7 +3676,7 @@ subroutine lak_cf(this, reset_mover)
           this%ibound(igwfnode) = 1
         end if
       end do
-
+      !
     end do
     !
     ! -- Store the lake stage and cond in bound array for other
@@ -3922,13 +3687,9 @@ subroutine lak_cf(this, reset_mover)
     return
   end subroutine lak_cf
 
+  !> @brief Copy rhs and hcof into solution rhs and amat
+  !<
   subroutine lak_fc(this, rhs, ia, idxglo, matrix_sln)
-    ! **************************************************************************
-    ! lak_fc -- Copy rhs and hcof into solution rhs and amat
-    ! **************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! --------------------------------------------------------------------------
     ! -- dummy
     class(LakType) :: this
     real(DP), dimension(:), intent(inout) :: rhs
@@ -3939,7 +3700,6 @@ subroutine lak_fc(this, rhs, ia, idxglo, matrix_sln)
     integer(I4B) :: j, n
     integer(I4B) :: igwfnode
     integer(I4B) :: ipossymd
-! --------------------------------------------------------------------------
     !
     ! -- pakmvrobj fc
     if (this%imover == 1) then
@@ -3960,17 +3720,13 @@ subroutine lak_fc(this, rhs, ia, idxglo, matrix_sln)
       end do
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_fc
 
+  !> @brief Fill newton terms
+  !<
   subroutine lak_fn(this, rhs, ia, idxglo, matrix_sln)
-! **************************************************************************
-! lak_fn -- Fill newton terms
-! **************************************************************************
-!
-!    SPECIFICATIONS:
-! --------------------------------------------------------------------------
     ! -- dummy
     class(LakType) :: this
     real(DP), dimension(:), intent(inout) :: rhs
@@ -3993,7 +3749,7 @@ subroutine lak_fn(this, rhs, ia, idxglo, matrix_sln)
     real(DP) :: q1
     real(DP) :: rterm
     real(DP) :: drterm
-! --------------------------------------------------------------------------
+    !
     do n = 1, this%nlakes
       if (this%iboundpak(n) == 0) cycle
       hlak = this%xnewpak(n)
@@ -4025,19 +3781,15 @@ subroutine lak_fn(this, rhs, ia, idxglo, matrix_sln)
         end if
       end do
     end do
-
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_fn
 
+  !> @brief Final convergence check for package
+  !<
   subroutine lak_cc(this, innertot, kiter, iend, icnvgmod, cpak, ipak, dpak)
-! **************************************************************************
-! lak_cc -- Final convergence check for package
-! **************************************************************************
-!
-!    SPECIFICATIONS:
-! --------------------------------------------------------------------------
+    ! -- modules
     use TdisModule, only: totim, kstp, kper, delt
     ! -- dummy
     class(LakType), intent(inout) :: this
@@ -4086,8 +3838,6 @@ subroutine lak_cc(this, innertot, kiter, iend, icnvgmod, cpak, ipak, dpak)
     real(DP) :: dqoutmax
     real(DP) :: dqfrommvr
     real(DP) :: dqfrommvrmax
-    ! format
-! --------------------------------------------------------------------------
     !
     ! -- initialize local variables
     icheck = this%iconvchk
@@ -4331,17 +4081,13 @@ subroutine lak_cc(this, innertot, kiter, iend, icnvgmod, cpak, ipak, dpak)
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_cc
 
+  !> @brief Calculate flows
+  !<
   subroutine lak_cq(this, x, flowja, iadv)
-! ******************************************************************************
-! lak_cq -- Calculate flows
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: delt
     ! -- dummy
@@ -4356,7 +4102,6 @@ subroutine lak_cq(this, x, flowja, iadv)
     integer(I4B) :: j, n
     real(DP) :: hlak
     real(DP) :: v0, v1
-! ------------------------------------------------------------------------------
     !
     call this%lak_solve(update=.false.)
     !
@@ -4440,10 +4185,12 @@ subroutine lak_cq(this, x, flowja, iadv)
     ! -- fill the budget object
     call this%lak_fill_budobj()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_cq
 
+  !> @brief Output LAK package flow terms
+  !<
   subroutine lak_ot_package_flows(this, icbcfl, ibudfl)
     use TdisModule, only: kstp, kper, delt, pertim, totim
     class(LakType) :: this
@@ -4466,9 +4213,13 @@ subroutine lak_ot_package_flows(this, icbcfl, ibudfl)
     if (ibudfl /= 0 .and. this%iprflow /= 0) then
       call this%budobj%write_flowtable(this%dis, kstp, kper)
     end if
-
+    !
+    ! -- Return
+    return
   end subroutine lak_ot_package_flows
 
+  !> @brief Write flows to binary file and/or print flows to budget
+  !<
   subroutine lak_ot_model_flows(this, icbcfl, ibudfl, icbcun, imap)
     class(LakType) :: this
     integer(I4B), intent(in) :: icbcfl
@@ -4478,8 +4229,13 @@ subroutine lak_ot_model_flows(this, icbcfl, ibudfl, icbcun, imap)
     !
     ! -- write the flows from the budobj
     call this%BndType%bnd_ot_model_flows(icbcfl, ibudfl, icbcun, this%imap)
+    !
+    ! -- Return
+    return
   end subroutine lak_ot_model_flows
 
+  !> @brief Save LAK-calculated values to binary file
+  !<
   subroutine lak_ot_dv(this, idvsave, idvprint)
     use TdisModule, only: kstp, kper, pertim, totim
     use ConstantsModule, only: DHNOFLO, DHDRY
@@ -4495,7 +4251,6 @@ subroutine lak_ot_dv(this, idvsave, idvprint)
     real(DP) :: sa
     real(DP) :: wa
     !
-    !
     ! -- set unit number for binary dependent variable output
     ibinun = 0
     if (this%istageout /= 0) then
@@ -4541,9 +4296,13 @@ subroutine lak_ot_dv(this, idvsave, idvprint)
         call this%stagetab%add_term(v)
       end do
     end if
-
+    !
+    ! -- Return
+    return
   end subroutine lak_ot_dv
 
+  !> @brief Write LAK budget to listing file
+  !<
   subroutine lak_ot_bdsummary(this, kstp, kper, iout, ibudfl)
     ! -- module
     use TdisModule, only: totim
@@ -4556,23 +4315,17 @@ subroutine lak_ot_bdsummary(this, kstp, kper, iout, ibudfl)
     !
     call this%budobj%write_budtable(kstp, kper, iout, ibudfl, totim)
     !
+    ! -- Return
     return
   end subroutine lak_ot_bdsummary
 
+  !> @brief Deallocate objects
+  !<
   subroutine lak_da(this)
-    ! **************************************************************************
-    ! lak_da -- Deallocate objects
-    ! **************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! --------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(LakType) :: this
-    ! -- local
-    ! -- format
-    ! --------------------------------------------------------------------------
     !
     ! -- arrays
     deallocate (this%lakename)
@@ -4622,9 +4375,11 @@ subroutine lak_da(this)
     !
     ! -- package csv table
     if (this%ipakcsv > 0) then
-      call this%pakcsvtab%table_da()
-      deallocate (this%pakcsvtab)
-      nullify (this%pakcsvtab)
+      if (associated(this%pakcsvtab)) then
+        call this%pakcsvtab%table_da()
+        deallocate (this%pakcsvtab)
+        nullify (this%pakcsvtab)
+      end if
     end if
     !
     ! -- scalars
@@ -4730,16 +4485,12 @@ subroutine lak_da(this)
     return
   end subroutine lak_da
 
+  !> @brief Define the list heading that is written to iout when PRINT_INPUT
+  !! option is used
+  !<
   subroutine define_listlabel(this)
-! ******************************************************************************
-! define_listlabel -- Define the list heading that is written to iout when
-!   PRINT_INPUT option is used.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     class(LakType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- create the header list label
     this%listlabel = trim(this%filtyp)//' NO.'
@@ -4758,26 +4509,21 @@ subroutine define_listlabel(this)
       write (this%listlabel, '(a, a16)') trim(this%listlabel), 'BOUNDARY NAME'
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine define_listlabel
 
+  !> @brief Set pointers to model arrays and variables so that a package has
+  !! access to these things
+  !<
   subroutine lak_set_pointers(this, neq, ibound, xnew, xold, flowja)
-! ******************************************************************************
-! set_pointers -- Set pointers to model arrays and variables so that a package
-!                 has access to these things.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     class(LakType) :: this
     integer(I4B), pointer :: neq
     integer(I4B), dimension(:), pointer, contiguous :: ibound
     real(DP), dimension(:), pointer, contiguous :: xnew
     real(DP), dimension(:), pointer, contiguous :: xold
     real(DP), dimension(:), pointer, contiguous :: flowja
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- call base BndType set_pointers
     call this%BndType%set_pointers(neq, ibound, xnew, xold, flowja)
@@ -4795,40 +4541,33 @@ subroutine lak_set_pointers(this, neq, ibound, xnew, xold, flowja)
     !  this%xnewpak(n) = DEP20
     !end do
     !
-    ! -- return
+    ! -- Return
+    return
   end subroutine lak_set_pointers
 
-  !
-  ! -- Procedures related to observations (type-bound)
+  !> @brief Procedures related to observations (type-bound)
+  !!
+  !! Return true because LAK package supports observations. Overrides
+  !! BndType%bnd_obs_supported()
+  !<
   logical function lak_obs_supported(this)
-    ! ******************************************************************************
-    ! lak_obs_supported
-    !   -- Return true because LAK package supports observations.
-    !   -- Overrides BndType%bnd_obs_supported()
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
-    ! ------------------------------------------------------------------------------
+    ! -- dummy
     class(LakType) :: this
+    !
     lak_obs_supported = .true.
+    !
+    ! -- Return
     return
   end function lak_obs_supported
 
+  !> @brief Store observation type supported by LAK package. Overrides
+  !! BndType%bnd_df_obs
+  !<
   subroutine lak_df_obs(this)
-    ! ******************************************************************************
-    ! lak_df_obs (implements bnd_df_obs)
-    !   -- Store observation type supported by LAK package.
-    !   -- Overrides BndType%bnd_df_obs
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType) :: this
     ! -- local
     integer(I4B) :: indx
-    ! ------------------------------------------------------------------------------
     !
     ! -- Store obs type and assign procedure pointer
     !    for stage observation type.
@@ -4925,18 +4664,14 @@ subroutine lak_df_obs(this)
     call this%obs%StoreObsType('conductance', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => lak_process_obsID
     !
+    ! -- Return
     return
   end subroutine lak_df_obs
 
+  !> @brief Calculate observations this time step and call ObsType%SaveOneSimval
+  !! for each LakType observation.
+  !<
   subroutine lak_bd_obs(this)
-    ! **************************************************************************
-    ! lak_bd_obs
-    !   -- Calculate observations this time step and call
-    !      ObsType%SaveOneSimval for each LakType observation.
-    ! **************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! --------------------------------------------------------------------------
     ! -- dummy
     class(LakType) :: this
     ! -- local
@@ -4950,7 +4685,6 @@ subroutine lak_bd_obs(this)
     real(DP) :: v
     real(DP) :: v2
     type(ObserveType), pointer :: obsrv => null()
-    !---------------------------------------------------------------------------
     !
     ! Write simulated values for all LAK observations
     if (this%obs%npakobs > 0) then
@@ -5089,9 +4823,15 @@ subroutine lak_bd_obs(this)
       end if
     end if
     !
+    ! -- Return
     return
   end subroutine lak_bd_obs
 
+  !> @brief Process each observation
+  !!
+  !! Only done the first stress period since boundaries are fixed for the
+  !! simulation
+  !<
   subroutine lak_rp_obs(this)
     use TdisModule, only: kper
     ! -- dummy
@@ -5103,9 +4843,8 @@ subroutine lak_rp_obs(this)
     integer(I4B) :: nn2
     integer(I4B) :: jj
     character(len=LENBOUNDNAME) :: bname
-    logical :: jfound
+    logical(LGP) :: jfound
     class(ObserveType), pointer :: obsrv => null()
-    ! --------------------------------------------------------------------------
     ! -- formats
 10  format('Boundary "', a, '" for observation "', a, &
            '" is invalid in package "', a, '"')
@@ -5237,14 +4976,18 @@ subroutine lak_rp_obs(this)
       end if
     end if
     !
+    ! -- Return
     return
   end subroutine lak_rp_obs
 
   !
   ! -- Procedures related to observations (NOT type-bound)
+
+  !> @brief This procedure is pointed to by ObsDataType%ProcesssIdPtr. It
+  !! processes the ID string of an observation definition for LAK package
+  !! observations.
+  !<
   subroutine lak_process_obsID(obsrv, dis, inunitobs, iout)
-    ! -- This procedure is pointed to by ObsDataType%ProcesssIdPtr. It processes
-    !    the ID string of an observation definition for LAK package observations.
     ! -- dummy
     type(ObserveType), intent(inout) :: obsrv
     class(DisBaseType), intent(in) :: dis
@@ -5255,7 +4998,6 @@ subroutine lak_process_obsID(obsrv, dis, inunitobs, iout)
     integer(I4B) :: icol, istart, istop
     character(len=LINELENGTH) :: strng
     character(len=LENBOUNDNAME) :: bndname
-    ! formats
     !
     strng = obsrv%IDstring
     ! -- Extract lake number from strng and store it.
@@ -5290,19 +5032,17 @@ subroutine lak_process_obsID(obsrv, dis, inunitobs, iout)
     ! -- store lake number (NodeNumber)
     obsrv%NodeNumber = nn1
     !
+    ! -- Return
     return
   end subroutine lak_process_obsID
 
   !
   ! -- private LAK methods
   !
+
+  !> @brief Accumulate constant head terms for budget
+  !<
   subroutine lak_accumulate_chterm(this, ilak, rrate, chratin, chratout)
-    ! **************************************************************************
-    ! lak_accumulate_chterm -- Accumulate constant head terms for budget.
-    ! **************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! --------------------------------------------------------------------------
     ! -- dummy
     class(LakType) :: this
     integer(I4B), intent(in) :: ilak
@@ -5311,7 +5051,7 @@ subroutine lak_accumulate_chterm(this, ilak, rrate, chratin, chratout)
     real(DP), intent(inout) :: chratout
     ! -- locals
     real(DP) :: q
-    ! format
+    !
     ! code
     if (this%iboundpak(ilak) < 0) then
       q = -rrate
@@ -5328,21 +5068,19 @@ subroutine lak_accumulate_chterm(this, ilak, rrate, chratin, chratout)
         chratin = chratin + q
       end if
     end if
-    ! -- return
+    !
+    ! -- Return
     return
   end subroutine lak_accumulate_chterm
 
+  !> @brief Update LAK satcond and package rhs and hcof
+  !<
   subroutine lak_cfupdate(this)
-    ! ******************************************************************************
-    ! lak_cfupdate -- Update LAK satcond and package rhs and hcof
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
+    ! -- dummy
     class(LakType), intent(inout) :: this
+    ! -- local
     integer(I4B) :: j, n, node
     real(DP) :: hlak, head, clak, blak
-    ! ------------------------------------------------------------------------------
     !
     ! -- Return if no lak lakes
     if (this%nbound .eq. 0) return
@@ -5380,18 +5118,14 @@ subroutine lak_cfupdate(this)
     return
   end subroutine lak_cfupdate
 
+  !> @brief Store the lake head and connection conductance in the bound array
+  !<
   subroutine lak_bound_update(this)
-    ! ******************************************************************************
-    ! lak_bound_update -- store the lake head and connection conductance in the
-    !   bound array
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
+    ! -- dummy
     class(LakType), intent(inout) :: this
+    ! -- local
     integer(I4B) :: j, n, node
     real(DP) :: hlak, head, clak
-    ! ------------------------------------------------------------------------------
     !
     ! -- Return if no lak lakes
     if (this%nbound == 0) return
@@ -5412,19 +5146,16 @@ subroutine lak_bound_update(this)
     return
   end subroutine lak_bound_update
 
+  !> @brief Solve for lake stage
+  !<
   subroutine lak_solve(this, update)
-    ! **************************************************************************
-    ! lak_solve -- Solve for lake stage
-    ! **************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! --------------------------------------------------------------------------
+    ! -- modules
     use TdisModule, only: delt
-    logical, intent(in), optional :: update
     ! -- dummy
     class(LakType), intent(inout) :: this
+    logical(LGP), intent(in), optional :: update
     ! -- local
-    logical :: lupdate
+    logical(LGP) :: lupdate
     integer(I4B) :: i
     integer(I4B) :: j
     integer(I4B) :: n
@@ -5465,7 +5196,6 @@ subroutine lak_solve(this, update)
     real(DP) :: ts
     real(DP) :: area
     real(DP) :: qtolfact
-! --------------------------------------------------------------------------
     !
     ! -- set lupdate
     if (present(update)) then
@@ -5526,10 +5256,10 @@ subroutine lak_solve(this, update)
       call this%lak_calculate_outlet_inflow(n, outinf)
       this%flwin(n) = this%flwin(n) + outinf
     end do
-
+    !
     iicnvg = 0
     maxiter = this%maxlakit
-
+    !
     ! -- outer loop
     converge: do iter = 1, maxiter
       ncnv = 0
@@ -5538,7 +5268,7 @@ subroutine lak_solve(this, update)
       end do
       if (iter == maxiter) ncnv = 0
       if (ncnv == 0) iicnvg = 1
-
+      !
       ! -- initialize variables
       do n = 1, this%nlakes
         this%evap(n) = DZERO
@@ -5558,7 +5288,7 @@ subroutine lak_solve(this, update)
           this%flwiter1(n) = DEP20 !1.D+10
         end if
       end do
-
+      !
       estseep: do i = 1, 2
         lakseep: do n = 1, this%nlakes
           ! -- skip inactive lakes
@@ -5602,11 +5332,11 @@ subroutine lak_solve(this, update)
                 end if
               end if
             end if
-
+            !
           end do calcconnseep
         end do lakseep
       end do estseep
-
+      !
       laklevel: do n = 1, this%nlakes
         ibflg = 0
         hlak = this%xnewpak(n)
@@ -5656,7 +5386,6 @@ subroutine lak_solve(this, update)
             call this%lak_calculate_external(n, ex)
             this%flwin(n) = this%surfin(n) + ro + qinf + ex + &
                             max(v0, v1) / delt
-
             !
             ! -- compute new lake stage using Newton's method
             resid = this%precip(n) + this%evap(n) + this%withr(n) + ro + &
@@ -5769,9 +5498,9 @@ subroutine lak_solve(this, update)
           this%dh0(n) = dh
         end if
       end do laklevel
-
+      !
       if (iicnvg == 1) exit converge
-
+      !
     end do converge
     !
     ! -- Mover terms: store outflow after diversion loss
@@ -5783,14 +5512,13 @@ subroutine lak_solve(this, update)
       end do
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_solve
 
   !> @ brief Lake package bisection method
-    !!
-    !!  Use bisection method to find lake stage that reduces the residual
-    !!
+  !!
+  !!  Use bisection method to find lake stage that reduces the residual
   !<
   subroutine lak_bisection(this, n, ibflg, hlak, temporary_stage, dh, residual)
     ! -- dummy
@@ -5836,19 +5564,16 @@ subroutine lak_bisection(this, n, ibflg, hlak, temporary_stage, dh, residual)
     end do
     dh = hlak - temporary_stage
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_bisection
 
+  !> @brief Calculate the available volumetric rate for a lake given a passed
+  !! stage
+  !<
   subroutine lak_calculate_available(this, n, hlak, avail, &
                                      ra, ro, qinf, ex, headp)
-    ! **************************************************************************
-    ! lak_calculate_available -- Calculate the available volumetric rate for
-    !                            a lake given a passed stage
-    ! **************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! --------------------------------------------------------------------------
+    ! -- modules
     use TdisModule, only: delt
     ! -- dummy
     class(LakType), intent(inout) :: this
@@ -5868,7 +5593,6 @@ subroutine lak_calculate_available(this, n, hlak, avail, &
     real(DP) :: head
     real(DP) :: qlakgw
     real(DP) :: v0
-    ! code
     !
     ! -- set hp
     if (present(headp)) then
@@ -5909,18 +5633,14 @@ subroutine lak_calculate_available(this, n, hlak, avail, &
     call this%lak_calculate_vol(n, this%xoldpak(n), v0)
     avail = avail + v0 / delt
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_available
 
+  !> @brief Calculate the residual for a lake given a passed stage
+  !<
   subroutine lak_calculate_residual(this, n, hlak, resid, headp)
-    ! **************************************************************************
-    ! lak_calculate_residual -- Calculate the residual for a lake given a
-    !                           passed stage
-    ! **************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! --------------------------------------------------------------------------
+    ! -- modules
     use TdisModule, only: delt
     ! -- dummy
     class(LakType), intent(inout) :: this
@@ -5949,8 +5669,6 @@ subroutine lak_calculate_residual(this, n, hlak, resid, headp)
     real(DP) :: v0
     real(DP) :: v1
     !
-    ! -- code
-    !
     ! -- set hp
     if (present(headp)) then
       hp = headp
@@ -6000,17 +5718,13 @@ subroutine lak_calculate_residual(this, n, hlak, resid, headp)
       resid = resid + (v0 - v1) / delt
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_residual
 
+  !> @brief Set up the budget object that stores all the lake flows
+  !<
   subroutine lak_setup_budobj(this)
-! ******************************************************************************
-! lak_setup_budobj -- Set up the budget object that stores all the lake flows
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LENBUDTXT
     ! -- dummy
@@ -6024,7 +5738,6 @@ subroutine lak_setup_budobj(this)
     real(DP) :: q
     character(len=LENBUDTXT) :: text
     character(len=LENBUDTXT), dimension(1) :: auxtxt
-! ------------------------------------------------------------------------------
     !
     ! -- Determine the number of lake budget terms. These are fixed for
     !    the simulation and cannot change
@@ -6260,18 +5973,13 @@ subroutine lak_setup_budobj(this)
       call this%budobj%flowtable_df(this%iout)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_setup_budobj
 
+  !> @brief Copy flow terms into this%budobj
+  !<
   subroutine lak_fill_budobj(this)
-! ******************************************************************************
-! lak_fill_budobj -- copy flow terms into this%budobj
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(LakType) :: this
     ! -- local
@@ -6289,8 +5997,6 @@ subroutine lak_fill_budobj(this)
     real(DP) :: v, v1
     real(DP) :: q
     real(DP) :: lkstg, gwhead, wa
-    ! -- formats
-! -----------------------------------------------------------------------------
     !
     ! -- initialize counter
     idx = 0
@@ -6318,7 +6024,7 @@ subroutine lak_fill_budobj(this)
         end if
       end do
     end if
-
+    !
     ! -- GWF (LEAKAGE)
     idx = idx + 1
     call this%budobj%budterm(idx)%reset(this%maxbound)
@@ -6340,7 +6046,7 @@ subroutine lak_fill_budobj(this)
         call this%budobj%budterm(idx)%update_term(n, n2, q, this%qauxcbc)
       end do
     end do
-
+    !
     ! -- RAIN
     idx = idx + 1
     call this%budobj%budterm(idx)%reset(this%nlakes)
@@ -6348,7 +6054,7 @@ subroutine lak_fill_budobj(this)
       q = this%precip(n)
       call this%budobj%budterm(idx)%update_term(n, n, q)
     end do
-
+    !
     ! -- EVAPORATION
     idx = idx + 1
     call this%budobj%budterm(idx)%reset(this%nlakes)
@@ -6356,7 +6062,7 @@ subroutine lak_fill_budobj(this)
       q = this%evap(n)
       call this%budobj%budterm(idx)%update_term(n, n, q)
     end do
-
+    !
     ! -- RUNOFF
     idx = idx + 1
     call this%budobj%budterm(idx)%reset(this%nlakes)
@@ -6364,7 +6070,7 @@ subroutine lak_fill_budobj(this)
       q = this%runoff(n)
       call this%budobj%budterm(idx)%update_term(n, n, q)
     end do
-
+    !
     ! -- INFLOW
     idx = idx + 1
     call this%budobj%budterm(idx)%reset(this%nlakes)
@@ -6372,7 +6078,7 @@ subroutine lak_fill_budobj(this)
       q = this%inflow(n)
       call this%budobj%budterm(idx)%update_term(n, n, q)
     end do
-
+    !
     ! -- WITHDRAWAL
     idx = idx + 1
     call this%budobj%budterm(idx)%reset(this%nlakes)
@@ -6380,7 +6086,7 @@ subroutine lak_fill_budobj(this)
       q = this%withr(n)
       call this%budobj%budterm(idx)%update_term(n, n, q)
     end do
-
+    !
     ! -- EXTERNAL OUTFLOW
     idx = idx + 1
     call this%budobj%budterm(idx)%reset(this%nlakes)
@@ -6391,7 +6097,7 @@ subroutine lak_fill_budobj(this)
       q = q + v
       call this%budobj%budterm(idx)%update_term(n, n, q)
     end do
-
+    !
     ! -- STORAGE
     idx = idx + 1
     call this%budobj%budterm(idx)%reset(this%nlakes)
@@ -6401,7 +6107,7 @@ subroutine lak_fill_budobj(this)
       this%qauxcbc(1) = v1
       call this%budobj%budterm(idx)%update_term(n, n, q, this%qauxcbc)
     end do
-
+    !
     ! -- CONSTANT FLOW
     idx = idx + 1
     call this%budobj%budterm(idx)%reset(this%nlakes)
@@ -6409,10 +6115,10 @@ subroutine lak_fill_budobj(this)
       q = this%chterm(n)
       call this%budobj%budterm(idx)%update_term(n, n, q)
     end do
-
+    !
     ! -- MOVER
     if (this%imover == 1) then
-
+      !
       ! -- FROM MOVER
       idx = idx + 1
       call this%budobj%budterm(idx)%reset(this%nlakes)
@@ -6420,7 +6126,7 @@ subroutine lak_fill_budobj(this)
         q = this%pakmvrobj%get_qfrommvr(n)
         call this%budobj%budterm(idx)%update_term(n, n, q)
       end do
-
+      !
       ! -- TO MOVER
       idx = idx + 1
       call this%budobj%budterm(idx)%reset(this%noutlets)
@@ -6432,9 +6138,9 @@ subroutine lak_fill_budobj(this)
         end if
         call this%budobj%budterm(idx)%update_term(n1, n1, q)
       end do
-
+      !
     end if
-
+    !
     ! -- AUXILIARY VARIABLES
     naux = this%naux
     if (naux > 0) then
@@ -6455,20 +6161,16 @@ subroutine lak_fill_budobj(this)
     ! --Terms are filled, now accumulate them for this time step
     call this%budobj%accumulate_terms()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_fill_budobj
 
+  !> @brief Set up the table object that is used to write the lak stage data
+  !!
+  !! The terms listed here must correspond in number and order to the ones
+  !! written to the stage table in the lak_ot method
+  !<
   subroutine lak_setup_tableobj(this)
-! ******************************************************************************
-! lak_setup_tableobj -- Set up the table object that is used to write the lak
-!                       stage data. The terms listed here must correspond in
-!                       number and order to the ones written to the stage table
-!                       in the lak_ot method.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH, LENBUDTXT
     ! -- dummy
@@ -6477,7 +6179,6 @@ subroutine lak_setup_tableobj(this)
     integer(I4B) :: nterms
     character(len=LINELENGTH) :: title
     character(len=LINELENGTH) :: text
-! ------------------------------------------------------------------------------
     !
     ! -- setup stage table
     if (this%iprhed > 0) then
@@ -6527,23 +6228,17 @@ subroutine lak_setup_tableobj(this)
       call this%stagetab%initialize_column(text, 12, alignment=TABCENTER)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_setup_tableobj
 
+  !> @brief Activate addition of density terms
+  !<
   subroutine lak_activate_density(this)
-! ******************************************************************************
-! lak_activate_density -- Activate addition of density terms
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     ! -- local
     integer(I4B) :: i, j
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- Set idense and reallocate denseterms to be of size MAXBOUND
     this%idense = 1
@@ -6557,14 +6252,13 @@ subroutine lak_activate_density(this)
     write (this%iout, '(/1x,a)') 'DENSITY TERMS HAVE BEEN ACTIVATED FOR LAKE &
       &PACKAGE: '//trim(adjustl(this%packName))
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_activate_density
 
   !> @brief Activate viscosity terms
-    !!
-    !! Method to activate addition of viscosity terms for a LAK package reach.
-    !!
+  !!
+  !! Method to activate addition of viscosity terms for a LAK package reach.
   !<
   subroutine lak_activate_viscosity(this)
     ! -- modules
@@ -6587,36 +6281,30 @@ subroutine lak_activate_viscosity(this)
     write (this%iout, '(/1x,a)') 'VISCOSITY HAS BEEN ACTIVATED FOR LAK &
       &PACKAGE: '//trim(adjustl(this%packName))
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_activate_viscosity
 
+  !> @brief Calculate the groundwater-lake density exchange terms
+  !!
+  !! Arguments are as follows:
+  !!     iconn       : lak-gwf connection number
+  !!     stage       : lake stage
+  !!     head        : gwf head
+  !!     cond        : conductance
+  !!     botl        : bottom elevation of this connection
+  !!     flow        : calculated flow, updated here with density terms
+  !!     gwfhcof     : gwf head coefficient, updated here with density terms
+  !!     gwfrhs      : gwf right-hand-side value, updated here with density terms
+  !!
+  !! Member variable used here
+  !!     denseterms  : shape (3, MAXBOUND), filled by buoyancy package
+  !!                     col 1 is relative density of lake (denselak / denseref)
+  !!                     col 2 is relative density of gwf cell (densegwf / denseref)
+  !!                     col 3 is elevation of gwf cell
+  !<
   subroutine lak_calculate_density_exchange(this, iconn, stage, head, cond, &
                                             botl, flow, gwfhcof, gwfrhs)
-! ******************************************************************************
-! lak_calculate_density_exchange -- Calculate the groundwater-lake density
-!                                   exchange terms.
-!
-! -- Arguments are as follows:
-!     iconn       : lak-gwf connection number
-!     stage       : lake stage
-!     head        : gwf head
-!     cond        : conductance
-!     botl        : bottom elevation of this connection
-!     flow        : calculated flow, updated here with density terms
-!     gwfhcof     : gwf head coefficient, updated here with density terms
-!     gwfrhs      : gwf right-hand-side value, updated here with density terms
-!
-! -- Member variable used here
-!     denseterms  : shape (3, MAXBOUND), filled by buoyancy package
-!                     col 1 is relative density of lake (denselak / denseref)
-!                     col 2 is relative density of gwf cell (densegwf / denseref)
-!                     col 3 is elevation of gwf cell
-!
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(LakType), intent(inout) :: this
     integer(I4B), intent(in) :: iconn
@@ -6639,10 +6327,8 @@ subroutine lak_calculate_density_exchange(this, iconn, stage, head, cond, &
     real(DP) :: elevavg
     real(DP) :: d1
     real(DP) :: d2
-    logical :: stage_below_bot
-    logical :: head_below_bot
-    ! -- formats
-! ------------------------------------------------------------------------------
+    logical(LGP) :: stage_below_bot
+    logical(LGP) :: head_below_bot
     !
     ! -- Set lak density to lak density or gwf density
     if (stage >= botl) then
@@ -6708,7 +6394,7 @@ subroutine lak_calculate_density_exchange(this, iconn, stage, head, cond, &
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lak_calculate_density_exchange
 
diff --git a/src/Model/GroundWaterFlow/gwf3maw8.f90 b/src/Model/GroundWaterFlow/gwf3maw8.f90
index 59c79e205c6..df40289b0d3 100644
--- a/src/Model/GroundWaterFlow/gwf3maw8.f90
+++ b/src/Model/GroundWaterFlow/gwf3maw8.f90
@@ -18,7 +18,8 @@ module MawModule
   use TableModule, only: TableType, table_cr
   use ObserveModule, only: ObserveType
   use ObsModule, only: ObsType
-  use InputOutputModule, only: get_node, URWORD, extract_idnum_or_bndname, &
+  use GeomUtilModule, only: get_node
+  use InputOutputModule, only: URWORD, extract_idnum_or_bndname, &
                                GetUnit, openfile
   use BaseDisModule, only: DisBaseType
   use SimModule, only: count_errors, store_error, store_error_unit, &
@@ -163,7 +164,9 @@ module MawModule
     real(DP), dimension(:, :), pointer, contiguous :: viscratios => null() !< viscosity ratios (1: maw vsc ratio; 2: gwf vsc ratio)
     !
     ! -- type bound procedures
+
   contains
+
     procedure :: maw_allocate_scalars
     procedure :: maw_allocate_well_conn_arrays
     procedure :: maw_allocate_arrays
@@ -223,15 +226,12 @@ module MawModule
 
 contains
 
+!> @brief Create a New Multi-Aquifer Well (MAW) Package
+!!
+!! After creating the package object point bndobj to the new package
+!<
   subroutine maw_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
-! ******************************************************************************
-! maw_create -- Create a New Multi-Aquifer Well Package
-! Subroutine: (1) create new-style package
-!             (2) point bndobj to the new package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     class(BndType), pointer :: packobj
     integer(I4B), intent(in) :: id
     integer(I4B), intent(in) :: ibcnum
@@ -240,7 +240,6 @@ subroutine maw_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     character(len=*), intent(in) :: namemodel
     character(len=*), intent(in) :: pakname
     type(MawType), pointer :: mawobj
-! ------------------------------------------------------------------------------
     !
     ! -- allocate the object and assign values to object variables
     allocate (mawobj)
@@ -255,7 +254,7 @@ subroutine maw_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     !
     ! -- initialize package
     call packobj%pack_initialize()
-
+    !
     packobj%inunit = inunit
     packobj%iout = iout
     packobj%id = id
@@ -265,22 +264,17 @@ subroutine maw_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     packobj%isadvpak = 1
     packobj%ictMemPath = create_mem_path(namemodel, 'NPF')
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_create
 
+  !> @brief Allocate scalar members
+  !<
   subroutine maw_allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars -- allocate scalar members
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(MawType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- call standard BndType allocate scalars
     call this%BndType%allocate_scalars()
@@ -326,17 +320,13 @@ subroutine maw_allocate_scalars(this)
     this%idense = 0
     this%ivsc = 0
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_allocate_scalars
 
+  !> @brief Allocate well arrays
+  !<
   subroutine maw_allocate_well_conn_arrays(this)
-! ******************************************************************************
-! maw_allocate_arrays -- allocate well arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
@@ -345,7 +335,6 @@ subroutine maw_allocate_well_conn_arrays(this)
     integer(I4B) :: j
     integer(I4B) :: n
     integer(I4B) :: jj
-! ------------------------------------------------------------------------------
     !
     ! -- allocate character array for budget text
     call mem_allocate(this%cmawbudget, LENBUDTXT, this%bditems, 'CMAWBUDGET', &
@@ -531,39 +520,29 @@ subroutine maw_allocate_well_conn_arrays(this)
     ! -- allocate viscratios to size 0
     call mem_allocate(this%viscratios, 2, 0, 'VISCRATIOS', this%memoryPath)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_allocate_well_conn_arrays
 
+  !> @brief Allocate arrays
+  !<
   subroutine maw_allocate_arrays(this)
-! ******************************************************************************
-! maw_allocate_arrays -- allocate arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(MawType), intent(inout) :: this
     ! -- local
-    !integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     ! -- call standard BndType allocate scalars
     call this%BndType%allocate_arrays()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_allocate_arrays
 
+  !> @brief Read the packagedata for this package
+  !<
   subroutine maw_read_wells(this)
-! ******************************************************************************
-! maw_read_wells -- Read the packagedata for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use ConstantsModule, only: LINELENGTH
     use TimeSeriesManagerModule, only: read_value_or_time_series_adv
     ! -- dummy
@@ -601,9 +580,6 @@ subroutine maw_read_wells(this)
     character(len=*), parameter :: fmthdbot = &
       "('well head (', G0, ') must be greater than or equal to the &
       &BOTTOM_ELEVATION (', G0, ').')"
-! ------------------------------------------------------------------------------
-    !
-    ! -- code
     !
     ! -- allocate and initialize temporary variables
     allocate (strttext(this%nmawwells))
@@ -815,17 +791,13 @@ subroutine maw_read_wells(this)
     deallocate (radius)
     deallocate (bottom)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_read_wells
 
+  !> @brief Read the dimensions for this package
+  !<
   subroutine maw_read_well_connections(this)
-! ******************************************************************************
-! pak1read_dimensions -- Read the dimensions for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use ConstantsModule, only: LINELENGTH
     ! -- dummy
     class(MawType), intent(inout) :: this
@@ -852,11 +824,6 @@ subroutine maw_read_well_connections(this)
     real(DP) :: botw
     integer(I4B), dimension(:), pointer, contiguous :: nboundchk
     integer(I4B), dimension(:), pointer, contiguous :: iachk
-
-! ------------------------------------------------------------------------------
-    ! -- format
-    !
-    ! -- code
     !
     ! -- initialize counters
     ireset_scrntop = 0
@@ -1072,17 +1039,13 @@ subroutine maw_read_well_connections(this)
       call this%parser%StoreErrorUnit()
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_read_well_connections
 
+  !> @brief Read the dimensions for this package
+  !<
   subroutine maw_read_dimensions(this)
-! ******************************************************************************
-! pak1read_dimensions -- Read the dimensions for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use ConstantsModule, only: LINELENGTH
     ! -- dummy
     class(MawType), intent(inout) :: this
@@ -1091,7 +1054,6 @@ subroutine maw_read_dimensions(this)
     integer(I4B) :: ierr
     logical :: isfound, endOfBlock
     ! -- format
-! ------------------------------------------------------------------------------
     !
     ! -- initialize dimensions to -1
     this%nmawwells = -1
@@ -1153,17 +1115,13 @@ subroutine maw_read_dimensions(this)
     ! -- setup the head table object
     call this%maw_setup_tableobj()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_read_dimensions
 
+  !> @brief Read the initial parameters for this package
+  !<
   subroutine maw_read_initial_attr(this)
-! ******************************************************************************
-! maw_read_initial_attr -- Read the initial parameters for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH
     use MemoryManagerModule, only: mem_setptr
@@ -1204,7 +1162,6 @@ subroutine maw_read_initial_attr(this)
       &/1X,2(A10,1X),A20,7(A10,1X))"
     character(len=*), parameter :: fmtwellcd = &
       &"(1X,2(I10,1X),A20,1X,2(G10.3,1X),2(A10,1X),3(G10.3,1X))"
-! ------------------------------------------------------------------------------
     !
     ! -- initialize xnewpak
     do n = 1, this%nmawwells
@@ -1388,18 +1345,13 @@ subroutine maw_read_initial_attr(this)
       call store_error_unit(this%inunit)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_read_initial_attr
 
+  !> @brief Set a stress period attribute for mawweslls(imaw) using keywords
+  !<
   subroutine maw_set_stressperiod(this, imaw, iheadlimit_warning)
-! ******************************************************************************
-! maw_set_stressperiod -- Set a stress period attribute for mawweslls(imaw)
-!                         using keywords.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TimeSeriesManagerModule, only: read_value_or_time_series_adv
     ! -- dummy
@@ -1420,7 +1372,6 @@ subroutine maw_set_stressperiod(this, imaw, iheadlimit_warning)
     ! -- formats
     character(len=*), parameter :: fmthdbot = &
       &"('well head (',G0,') must be >= BOTTOM_ELEVATION (',G0, ').')"
-! ------------------------------------------------------------------------------
     !
     ! -- read remainder of variables on the line
     call this%parser%GetStringCaps(keyword)
@@ -1529,19 +1480,13 @@ subroutine maw_set_stressperiod(this, imaw, iheadlimit_warning)
     end select
 
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_set_stressperiod
 
+  !> @brief Issue a parameter error for mawweslls(imaw)
+  !<
   subroutine maw_set_attribute_error(this, imaw, keyword, msg)
-! ******************************************************************************
-! maw_set_attribute_error -- Issue a parameter error for mawweslls(imaw)
-! Subroutine: (1) read itmp
-!             (2) read new boundaries if itmp>0
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use SimModule, only: store_error
     ! -- dummy
     class(MawType), intent(inout) :: this
@@ -1550,7 +1495,7 @@ subroutine maw_set_attribute_error(this, imaw, keyword, msg)
     character(len=*), intent(in) :: msg
     ! -- local
     ! -- formats
-! ------------------------------------------------------------------------------
+    !
     if (len(msg) == 0) then
       write (errmsg, '(a,1x,a,1x,i0,1x,a)') &
         keyword, ' for MAW well', imaw, 'has already been set.'
@@ -1560,19 +1505,13 @@ subroutine maw_set_attribute_error(this, imaw, keyword, msg)
     end if
     call store_error(errmsg)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_set_attribute_error
 
+  !> @brief Issue parameter errors for mawwells(imaw)
+  !<
   subroutine maw_check_attributes(this)
-! ******************************************************************************
-! maw_check_attributes -- Issue parameter errors for mawwells(imaw)
-! Subroutine: (1) read itmp
-!             (2) read new boundaries if itmp>0
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use SimModule, only: store_error
     ! -- dummy
     class(MawType), intent(inout) :: this
@@ -1583,7 +1522,7 @@ subroutine maw_check_attributes(this)
     integer(I4B) :: j
     integer(I4B) :: jpos
     ! -- formats
-! ------------------------------------------------------------------------------
+    !
     idx = 1
     do n = 1, this%nmawwells
       if (this%ngwfnodes(n) < 1) then
@@ -1639,17 +1578,13 @@ subroutine maw_check_attributes(this)
     end do
     ! -- reset check_attr
     this%check_attr = 0
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_check_attributes
 
+  !> @brief Add package connection to matrix
+  !<
   subroutine maw_ac(this, moffset, sparse)
-! ******************************************************************************
-! bnd_ac -- Add package connection to matrix
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use SparseModule, only: sparsematrix
     ! -- dummy
     class(MawType), intent(inout) :: this
@@ -1662,8 +1597,6 @@ subroutine maw_ac(this, moffset, sparse)
     integer(I4B) :: jglo
     integer(I4B) :: nglo
     ! -- format
-! ------------------------------------------------------------------------------
-    !
     !
     ! -- Add package rows to sparse
     do n = 1, this%nmawwells
@@ -1678,17 +1611,13 @@ subroutine maw_ac(this, moffset, sparse)
 
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_ac
 
+  !> @brief Map package connection to matrix
+  !<
   subroutine maw_mc(this, moffset, matrix_sln)
-! ******************************************************************************
-! bnd_ac -- map package connection to matrix
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use SparseModule, only: sparsematrix
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
@@ -1703,7 +1632,6 @@ subroutine maw_mc(this, moffset, matrix_sln)
     integer(I4B) :: jglo
     integer(I4B) :: ipos
     ! -- format
-! ------------------------------------------------------------------------------
     !
     ! -- allocate connection mapping vectors
     call mem_allocate(this%idxlocnode, this%nmawwells, 'IDXLOCNODE', &
@@ -1744,18 +1672,15 @@ subroutine maw_mc(this, moffset, matrix_sln)
       end do
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_mc
 
+  !> @brief Set options specific to MawType.
+  !!
+  !! Overrides BndType%bnd_options
+  !<
   subroutine maw_read_options(this, option, found)
-! ******************************************************************************
-! maw_read_options -- set options specific to MawType.
-!                     Overrides BndType%bnd_options
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use ConstantsModule, only: MAXCHARLEN, DZERO, MNORMAL
     use OpenSpecModule, only: access, form
     use InputOutputModule, only: urword, getunit, openfile
@@ -1775,7 +1700,6 @@ subroutine maw_read_options(this, option, found)
     character(len=*), parameter :: fmtmawbin = &
       "(4x, 'MAW ', 1x, a, 1x, ' WILL BE SAVED TO FILE: ', a, /4x, &
      &'OPENED ON UNIT: ', I0)"
-! ------------------------------------------------------------------------------
     !
     ! -- Check for 'FLOWING_WELLS' and set this%iflowingwells
     found = .true.
@@ -1869,24 +1793,19 @@ subroutine maw_read_options(this, option, found)
       found = .false.
     end select
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_read_options
 
+  !> @brief Allocate and Read
+  !!
+  !! Create new MAW package and point bndobj to the new package
+  !<
   subroutine maw_ar(this)
-    ! ******************************************************************************
-    ! maw_ar -- Allocate and Read
-    ! Subroutine: (1) create new-style package
-    !             (2) point bndobj to the new package
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
     ! -- dummy
     class(MawType), intent(inout) :: this
     ! -- local
     ! -- format
-    ! ------------------------------------------------------------------------------
     !
     call this%obs%obs_ar()
     !
@@ -1907,19 +1826,15 @@ subroutine maw_ar(this)
       call this%pakmvrobj%ar(this%nmawwells, this%nmawwells, this%memoryPath)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_ar
 
+  !> @brief Read and Prepare
+  !!
+  !! Read itmp and new boundaries if itmp > 0
+  !<
   subroutine maw_rp(this)
-! ******************************************************************************
-! maw_rp -- Read and Prepare
-! Subroutine: (1) read itmp
-!             (2) read new boundaries if itmp>0
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use ConstantsModule, only: LINELENGTH
     use TdisModule, only: kper, nper
     ! -- dummy
@@ -1946,7 +1861,6 @@ subroutine maw_rp(this)
       &"('Looking for BEGIN PERIOD iper.  Found ', a, ' instead.')"
     character(len=*), parameter :: fmtlsp = &
       &"(1X,/1X,'REUSING ',A,'S FROM LAST STRESS PERIOD')"
-! ------------------------------------------------------------------------------
     !
     ! -- initialize counters
     iheadlimit_warning = 0
@@ -2201,17 +2115,13 @@ subroutine maw_rp(this)
       end do
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_rp
 
+  !> @brief Add package connection to matrix
+  !<
   subroutine maw_ad(this)
-! ******************************************************************************
-! maw_ad -- Add package connection to matrix
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use TdisModule, only: kper, kstp
     ! -- dummy
     class(MawType) :: this
@@ -2220,7 +2130,6 @@ subroutine maw_ad(this)
     integer(I4B) :: j
     integer(I4B) :: jj
     integer(I4B) :: ibnd
-! ------------------------------------------------------------------------------
     !
     ! -- Advance the time series
     call this%TsManager%ad()
@@ -2275,47 +2184,29 @@ subroutine maw_ad(this)
     !    "current" value.
     call this%obs%obs_ad()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_ad
 
-  subroutine maw_cf(this, reset_mover)
-    ! ******************************************************************************
-    ! maw_cf -- Formulate the HCOF and RHS terms
-    ! Subroutine: (1) skip if no multi-aquifer wells
-    !             (2) calculate hcof and rhs
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
+  !> @brief Formulate the HCOF and RHS terms
+  !!
+  !! Skip if no multi-aquifer wells, otherwise, calculate hcof and rhs
+  !<
+  subroutine maw_cf(this)
     ! -- dummy
     class(MawType) :: this
-    logical, intent(in), optional :: reset_mover
     ! -- local
-    logical :: lrm
-    ! ------------------------------------------------------------------------------
     !
     ! -- Calculate maw conductance and update package RHS and HCOF
     call this%maw_cfupdate()
     !
-    ! -- pakmvrobj cf
-    lrm = .true.
-    if (present(reset_mover)) lrm = reset_mover
-    if (this%imover == 1 .and. lrm) then
-      call this%pakmvrobj%cf()
-    end if
-    !
     ! -- Return
     return
   end subroutine maw_cf
 
+  !> @brief Copy rhs and hcof into solution rhs and amat
+  !<
   subroutine maw_fc(this, rhs, ia, idxglo, matrix_sln)
-! ******************************************************************************
-! maw_fc -- Copy rhs and hcof into solution rhs and amat
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: delt
     ! -- dummy
@@ -2350,7 +2241,6 @@ subroutine maw_fc(this, rhs, ia, idxglo, matrix_sln)
     real(DP) :: rate
     real(DP) :: ratefw
     real(DP) :: flow
-! --------------------------------------------------------------------------
     !
     ! -- pakmvrobj fc
     if (this%imover == 1) then
@@ -2465,18 +2355,13 @@ subroutine maw_fc(this, rhs, ia, idxglo, matrix_sln)
       end do
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_fc
 
+  !> @brief Fill newton terms
+  !<
   subroutine maw_fn(this, rhs, ia, idxglo, matrix_sln)
-! **************************************************************************
-! maw_fn -- Fill newton terms
-! **************************************************************************
-!
-!    SPECIFICATIONS:
-! --------------------------------------------------------------------------
-    !use TdisModule, only:delt
     ! -- dummy
     class(MawType) :: this
     real(DP), dimension(:), intent(inout) :: rhs
@@ -2514,7 +2399,6 @@ subroutine maw_fn(this, rhs, ia, idxglo, matrix_sln)
     real(DP) :: flow
     real(DP) :: term2
     real(DP) :: rhsterm
-! --------------------------------------------------------------------------
     !
     ! -- Calculate Newton-Raphson corrections
     idx = 1
@@ -2636,19 +2520,14 @@ subroutine maw_fn(this, rhs, ia, idxglo, matrix_sln)
       end do
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_fn
 
+  !> @brief Calculate under-relaxation of groundwater flow model MAW Package heads
+  !! for current outer iteration using the well bottom
+  !<
   subroutine maw_nur(this, neqpak, x, xtemp, dx, inewtonur, dxmax, locmax)
-! ******************************************************************************
-! maw_nur -- under-relaxation
-! Subroutine: (1) Under-relaxation of Groundwater Flow Model MAW Package Heads
-!                 for current outer iteration using the well bottom
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(MawType), intent(inout) :: this
     integer(I4B), intent(in) :: neqpak
@@ -2663,8 +2542,6 @@ subroutine maw_nur(this, neqpak, x, xtemp, dx, inewtonur, dxmax, locmax)
     real(DP) :: botw
     real(DP) :: xx
     real(DP) :: dxx
-! ------------------------------------------------------------------------------
-
     !
     ! -- Newton-Raphson under-relaxation
     do n = 1, this%nmawwells
@@ -2690,13 +2567,9 @@ subroutine maw_nur(this, neqpak, x, xtemp, dx, inewtonur, dxmax, locmax)
     return
   end subroutine maw_nur
 
+  !> @brief Calculate flows
+  !<
   subroutine maw_cq(this, x, flowja, iadv)
-! **************************************************************************
-! maw_cq -- Calculate flows
-! **************************************************************************
-!
-!    SPECIFICATIONS:
-! --------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: delt
     use ConstantsModule, only: LENBOUNDNAME
@@ -2716,7 +2589,6 @@ subroutine maw_cq(this, x, flowja, iadv)
     real(DP) :: cfw
     ! -- for observations
     ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- recalculate package HCOF and RHS terms with latest groundwater and
     !    maw heads prior to calling base budget functionality
@@ -2811,11 +2683,14 @@ subroutine maw_cq(this, x, flowja, iadv)
     ! -- fill the budget object
     call this%maw_fill_budobj()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_cq
 
+  !> @brief Write flows to binary file and/or print flows to budget
+  !<
   subroutine maw_ot_model_flows(this, icbcfl, ibudfl, icbcun, imap)
+    ! -- dummy
     class(MawType) :: this
     integer(I4B), intent(in) :: icbcfl
     integer(I4B), intent(in) :: ibudfl
@@ -2826,6 +2701,8 @@ subroutine maw_ot_model_flows(this, icbcfl, ibudfl, icbcun, imap)
     call this%BndType%bnd_ot_model_flows(icbcfl, ibudfl, icbcun, this%imap)
   end subroutine maw_ot_model_flows
 
+  !> @brief Output MAW package flow terms.
+  !<
   subroutine maw_ot_package_flows(this, icbcfl, ibudfl)
     use TdisModule, only: kstp, kper, delt, pertim, totim
     class(MawType) :: this
@@ -2848,9 +2725,13 @@ subroutine maw_ot_package_flows(this, icbcfl, ibudfl)
     if (ibudfl /= 0 .and. this%iprflow /= 0) then
       call this%budobj%write_flowtable(this%dis, kstp, kper)
     end if
-
+    !
+    ! -- Return
+    return
   end subroutine maw_ot_package_flows
 
+  !> @brief Save maw-calculated values to binary file
+  !<
   subroutine maw_ot_dv(this, idvsave, idvprint)
     use TdisModule, only: kstp, kper, pertim, totim
     use ConstantsModule, only: DHNOFLO, DHDRY
@@ -2902,9 +2783,13 @@ subroutine maw_ot_dv(this, idvsave, idvprint)
         call this%headtab%add_term(this%xnewpak(n))
       end do
     end if
-
+    !
+    ! -- Return
+    return
   end subroutine maw_ot_dv
 
+  !> @brief Write MAW budget to listing file
+  !<
   subroutine maw_ot_bdsummary(this, kstp, kper, iout, ibudfl)
     ! -- module
     use TdisModule, only: totim
@@ -2917,24 +2802,18 @@ subroutine maw_ot_bdsummary(this, kstp, kper, iout, ibudfl)
     !
     call this%budobj%write_budtable(kstp, kper, iout, ibudfl, totim)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_ot_bdsummary
 
+  !> @brief Deallocate memory
+  !<
   subroutine maw_da(this)
-! ******************************************************************************
-! maw_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(MawType) :: this
     ! -- local
-    !integer(I4B) :: n
-! ------------------------------------------------------------------------------
     !
     ! -- budobj
     call this%budobj%budgetobject_da()
@@ -3042,20 +2921,15 @@ subroutine maw_da(this)
     ! -- call standard BndType deallocate
     call this%BndType%bnd_da()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_da
 
+  !> @brief Define the list heading that is written to iout when PRINT_INPUT
+  !! option is used.
+  !<
   subroutine define_listlabel(this)
-! ******************************************************************************
-! define_listlabel -- Define the list heading that is written to iout when
-!   PRINT_INPUT option is used.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     class(MawType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- create the header list label
     this%listlabel = trim(this%filtyp)//' NO.'
@@ -3074,18 +2948,14 @@ subroutine define_listlabel(this)
       write (this%listlabel, '(a, a16)') trim(this%listlabel), 'BOUNDARY NAME'
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine define_listlabel
 
+  !> @brief Set pointers to model arrays and variables so that a package has
+  !! has access to these things.
+  !<
   subroutine maw_set_pointers(this, neq, ibound, xnew, xold, flowja)
-! ******************************************************************************
-! set_pointers -- Set pointers to model arrays and variables so that a package
-!                 has access to these things.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate, mem_checkin
     ! -- dummy
@@ -3098,7 +2968,6 @@ subroutine maw_set_pointers(this, neq, ibound, xnew, xold, flowja)
     ! -- local
     integer(I4B) :: n
     integer(I4B) :: istart, iend
-! ------------------------------------------------------------------------------
     !
     ! -- call base BndType set_pointers
     call this%BndType%set_pointers(neq, ibound, xnew, xold, flowja)
@@ -3119,40 +2988,34 @@ subroutine maw_set_pointers(this, neq, ibound, xnew, xold, flowja)
       this%xnewpak(n) = DEP20
     end do
     !
-    ! -- return
+    ! -- Return
+    return
   end subroutine maw_set_pointers
 
-  !
   ! -- Procedures related to observations (type-bound)
+
+  !> @brief Return true because MAW package supports observations
+  !!
+  !! Overrides BndType%bnd_obs_supported()
+  !<
   logical function maw_obs_supported(this)
-    ! ******************************************************************************
-    ! maw_obs_supported
-    !   -- Return true because MAW package supports observations.
-    !   -- Overrides BndType%bnd_obs_supported()
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
     class(MawType) :: this
-    ! ------------------------------------------------------------------------------
+    !
     maw_obs_supported = .true.
+    !
+    ! -- Return
     return
   end function maw_obs_supported
 
+  !> @brief Store observation type supported by MAW package
+  !!
+  !! Overrides BndType%bnd_df_obs
+  !<
   subroutine maw_df_obs(this)
-    ! ******************************************************************************
-    ! maw_df_obs (implements bnd_df_obs)
-    !   -- Store observation type supported by MAW package.
-    !   -- Overrides BndType%bnd_df_obs
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
     ! -- dummy
     class(MawType) :: this
     ! -- local
     integer(I4B) :: indx
-    ! ------------------------------------------------------------------------------
     !
     ! -- Store obs type and assign procedure pointer
     !    for head observation type.
@@ -3209,18 +3072,14 @@ subroutine maw_df_obs(this)
     call this%obs%StoreObsType('fw-conductance', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => maw_process_obsID
     !
+    ! -- Return
     return
   end subroutine maw_df_obs
 
+  !> @brief Calculate observations this time step and call
+  !! ObsType%SaveOneSimval for each MawType observation.
+  !<
   subroutine maw_bd_obs(this)
-    ! **************************************************************************
-    ! maw_bd_obs
-    !   -- Calculate observations this time step and call
-    !      ObsType%SaveOneSimval for each MawType observation.
-    ! **************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! --------------------------------------------------------------------------
     ! -- dummy
     class(MawType) :: this
     ! -- local
@@ -3235,7 +3094,6 @@ subroutine maw_bd_obs(this)
     real(DP) :: v
     real(DP) :: qfact
     type(ObserveType), pointer :: obsrv => null()
-    !---------------------------------------------------------------------------
     !
     ! Calculate, save, and write simulated values for all MAW observations
     if (this%obs%npakobs > 0) then
@@ -3351,10 +3209,15 @@ subroutine maw_bd_obs(this)
       call this%maw_redflow_csv_write()
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_bd_obs
 
+  !> @brief Process each observation
+  !!
+  !! Only done the first stress period since boundaries are fixed for the
+  !! simulation
+  !<
   subroutine maw_rp_obs(this)
     use TdisModule, only: kper
     ! -- dummy
@@ -3369,14 +3232,10 @@ subroutine maw_rp_obs(this)
     character(len=LENBOUNDNAME) :: bname
     logical :: jfound
     class(ObserveType), pointer :: obsrv => null()
-    ! --------------------------------------------------------------------------
     ! -- formats
 10  format('Boundary "', a, '" for observation "', a, &
            '" is invalid in package "', a, '"')
     !
-    ! -- process each package observation
-    !    only done the first stress period since boundaries are fixed
-    !    for the simulation
     if (kper == 1) then
       do i = 1, this%obs%npakobs
         obsrv => this%obs%pakobs(i)%obsrv
@@ -3479,15 +3338,18 @@ subroutine maw_rp_obs(this)
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_rp_obs
 
   !
   ! -- Procedures related to observations (NOT type-bound)
+
+  !> @brief This procedure is pointed to by ObsDataType%ProcesssIdPtr. It
+  !! processes the ID string of an observation definition for MAW package
+  !! observations.
+  !<
   subroutine maw_process_obsID(obsrv, dis, inunitobs, iout)
-    ! -- This procedure is pointed to by ObsDataType%ProcesssIdPtr. It processes
-    !    the ID string of an observation definition for MAW package observations.
     ! -- dummy
     type(ObserveType), intent(inout) :: obsrv
     class(DisBaseType), intent(in) :: dis
@@ -3533,14 +3395,15 @@ subroutine maw_process_obsID(obsrv, dis, inunitobs, iout)
     ! -- store multi-aquifer well number (NodeNumber)
     obsrv%NodeNumber = nn1
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_process_obsID
 
   !
   ! -- private MAW methods
-  !
+
   !> @brief Initialize the auto flow reduce csv output file
+  !<
   subroutine maw_redflow_csv_init(this, fname)
     ! -- dummy variables
     class(MawType), intent(inout) :: this !< MawType object
@@ -3557,10 +3420,13 @@ subroutine maw_redflow_csv_init(this, fname)
       this%ioutredflowcsv
     write (this%ioutredflowcsv, '(a)') &
       'time,period,step,MAWnumber,rate-requested,rate-actual,maw-reduction'
+    !
+    ! -- Return
     return
   end subroutine maw_redflow_csv_init
 
   !> @brief MAW reduced flows only when & where they occur
+  !<
   subroutine maw_redflow_csv_write(this)
     ! -- modules
     use TdisModule, only: totim, kstp, kper
@@ -3584,8 +3450,14 @@ subroutine maw_redflow_csv_write(this)
           totim, kper, kstp, n, this%rate(n), this%ratesim(n), v
       end if
     end do
+    !
+    ! -- Return
+    return
   end subroutine maw_redflow_csv_write
 
+  !> @brief Calculate the appropriate saturated conductance to use based on
+  !! aquifer and multi-aquifer well characteristics
+  !<
   subroutine maw_calculate_satcond(this, i, j, node)
     ! -- dummy
     class(MawType), intent(inout) :: this
@@ -3624,7 +3496,6 @@ subroutine maw_calculate_satcond(this, i, j, node)
     real(DP) :: yx4
     real(DP) :: xy4
     ! -- formats
-    ! ------------------------------------------------------------------------------
     !
     ! -- initialize conductance variables
     iTcontrastErr = 0
@@ -3748,10 +3619,12 @@ subroutine maw_calculate_satcond(this, i, j, node)
     ! -- set saturated conductance
     this%satcond(jpos) = c
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_calculate_satcond
 
+  !> @brief Calculate the saturation between the aquifer maw well_head
+  !<
   subroutine maw_calculate_saturation(this, n, j, node, sat)
     ! -- dummy
     class(MawType), intent(inout) :: this
@@ -3766,7 +3639,6 @@ subroutine maw_calculate_saturation(this, n, j, node, sat)
     real(DP) :: topw
     real(DP) :: botw
     ! -- formats
-    ! ------------------------------------------------------------------------------
     !
     ! -- initialize saturation
     sat = DZERO
@@ -3809,31 +3681,24 @@ subroutine maw_calculate_saturation(this, n, j, node, sat)
       sat = DONE
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_calculate_saturation
 
+  !> @brief Calculate matrix terms for a multi-aquifer well connection. Terms
+  !! for fc and fn methods are calculated based on whether term2 is passed
+  !! Arguments are as follows:
+  !!     n       : maw well number
+  !!     j       : connection number for well n
+  !!     icflow  : flag indicating that flow should be corrected
+  !!     cmaw    : maw-gwf conducance
+  !!     cterm   : correction term for flow to dry cell
+  !!     term    : xxx
+  !!     flow    : calculated flow for this connection, positive into well
+  !!     term2   : xxx
+  !<
   subroutine maw_calculate_conn_terms(this, n, j, icflow, cmaw, cterm, term, &
                                       flow, term2)
-! ******************************************************************************
-! maw_calculate_conn_terms-- Calculate matrix terms for a multi-aquifer well
-!                            connection. Terms for fc and fn methods are
-!                            calculated based on whether term2 is passed
-!
-! -- Arguments are as follows:
-!     n       : maw well number
-!     j       : connection number for well n
-!     icflow  : flag indicating that flow should be corrected
-!     cmaw    : maw-gwf conducance
-!     cterm   : correction term for flow to dry cell
-!     term    : xxx
-!     flow    : calculated flow for this connection, positive into well
-!     term2   : xxx
-!
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(MawType) :: this
     integer(I4B), intent(in) :: n
@@ -3861,7 +3726,6 @@ subroutine maw_calculate_conn_terms(this, n, j, icflow, cmaw, cterm, term, &
     real(DP) :: drterm
     real(DP) :: dhbarterm
     real(DP) :: vscratio
-! ------------------------------------------------------------------------------
     !
     ! -- initialize terms
     cterm = DZERO
@@ -3973,19 +3837,14 @@ subroutine maw_calculate_conn_terms(this, n, j, icflow, cmaw, cterm, term, &
       call this%maw_calculate_density_exchange(jpos, hmaw, hgwf, cmaw, &
                                                bmaw, flow, term, cterm)
     end if
-
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_calculate_conn_terms
 
+  !> @brief Calculate well pumping rate based on constraints
+  !<
   subroutine maw_calculate_wellq(this, n, hmaw, q)
-! **************************************************************************
-! maw_calculate_wellq-- Calculate well pumping rate based on constraints
-! **************************************************************************
-!
-!    SPECIFICATIONS:
-! --------------------------------------------------------------------------
     ! -- dummy
     class(MawType) :: this
     integer(I4B), intent(in) :: n
@@ -3998,7 +3857,6 @@ subroutine maw_calculate_wellq(this, n, hmaw, q)
     real(DP) :: rate
     real(DP) :: weight
     real(DP) :: dq
-! --------------------------------------------------------------------------
     !
     ! -- Initialize q
     q = DZERO
@@ -4148,17 +4006,13 @@ subroutine maw_calculate_wellq(this, n, hmaw, q)
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_calculate_wellq
 
+  !> @brief Calculate groundwater inflow to a maw well
+  !<
   subroutine maw_calculate_qpot(this, n, qnet)
-! ******************************************************************************
-! maw_calculate_qpot -- Calculate groundwater inflow to a maw well
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use TdisModule, only: delt
     ! -- dummy
     class(MawType), intent(inout) :: this
@@ -4181,7 +4035,6 @@ subroutine maw_calculate_qpot(this, n, qnet)
     real(DP) :: hv
     real(DP) :: vscratio
     ! -- format
-! ------------------------------------------------------------------------------
     !
     ! -- initialize qnet and htmp
     qnet = DZERO
@@ -4242,17 +4095,13 @@ subroutine maw_calculate_qpot(this, n, qnet)
       qnet = qnet + cmaw * (hgwf - hv)
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_calculate_qpot
 
+  !> @brief Update MAW satcond and package rhs and hcof
+  !<
   subroutine maw_cfupdate(this)
-    ! ******************************************************************************
-    ! maw_cfupdate -- Update MAW satcond and package rhs and hcof
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
     class(MawType) :: this
     ! -- dummy
     ! -- local
@@ -4266,7 +4115,6 @@ subroutine maw_cfupdate(this)
     real(DP) :: hmaw
     real(DP) :: cterm
     real(DP) :: term
-! ------------------------------------------------------------------------------
     !
     ! -- Return if no maw wells
     if (this%nbound .eq. 0) return
@@ -4309,15 +4157,11 @@ subroutine maw_cfupdate(this)
     return
   end subroutine maw_cfupdate
 
+  !> @brief Set up the budget object that stores all the maw flows
+  !! The terms listed here must correspond in number and order to the ones
+  !! listed in the maw_fill_budobj routine.
+  !<
   subroutine maw_setup_budobj(this)
-! ******************************************************************************
-! maw_setup_budobj -- Set up the budget object that stores all the maw flows
-!   The terms listed here must correspond in number and order to the ones
-!   listed in the maw_fill_budobj routine.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LENBUDTXT
     ! -- dummy
@@ -4330,7 +4174,6 @@ subroutine maw_setup_budobj(this)
     integer(I4B) :: idx
     character(len=LENBUDTXT) :: text
     character(len=LENBUDTXT), dimension(1) :: auxtxt
-! ------------------------------------------------------------------------------
     !
     ! -- Determine the number of maw budget terms. These are fixed for
     !    the simulation and cannot change.
@@ -4474,7 +4317,7 @@ subroutine maw_setup_budobj(this)
                                                maxlist, .false., .false., &
                                                naux)
       !
-      ! --
+      ! -- flowing-well flow to mover
       if (this%iflowingwells > 0) then
         !
         ! --
@@ -4492,7 +4335,7 @@ subroutine maw_setup_budobj(this)
       end if
     end if
     !
-    ! --
+    ! -- auxiliary variable
     naux = this%naux
     if (naux > 0) then
       !
@@ -4514,19 +4357,16 @@ subroutine maw_setup_budobj(this)
       call this%budobj%flowtable_df(this%iout)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_setup_budobj
 
+  !> @brief Copy flow terms into this%budobj
+  !!
+  !! terms include a combination of the following:
+  !! gwf rate [flowing_well] [storage] constant_flow [frommvr tomvr tomvrcf [tomvrfw]] [aux]
+  !<
   subroutine maw_fill_budobj(this)
-! ******************************************************************************
-! maw_fill_budobj -- copy flow terms into this%budobj
-!
-! gwf rate [flowing_well] [storage] constant_flow [frommvr tomvr tomvrcf [tomvrfw]] [aux]
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(MawType) :: this
@@ -4547,7 +4387,6 @@ subroutine maw_fill_budobj(this)
     real(DP) :: b
     real(DP) :: v
     ! -- formats
-! -----------------------------------------------------------------------------
     !
     ! -- initialize counter
     idx = 0
@@ -4732,20 +4571,16 @@ subroutine maw_fill_budobj(this)
     ! --Terms are filled, now accumulate them for this time step
     call this%budobj%accumulate_terms()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_fill_budobj
 
+  !> @brief Set up the table object that is used to write the maw head data
+  !!
+  !! The terms listed here must correspond in number and order to the ones
+  !! written to the head table in the maw_ot method.
+  !<
   subroutine maw_setup_tableobj(this)
-! ******************************************************************************
-! maw_setup_tableobj -- Set up the table object that is used to write the maw
-!                       head data. The terms listed here must correspond in
-!                       number and order to the ones written to the head table
-!                       in the maw_ot method.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH, LENBUDTXT
     ! -- dummy
@@ -4754,7 +4589,6 @@ subroutine maw_setup_tableobj(this)
     integer(I4B) :: nterms
     character(len=LINELENGTH) :: title
     character(len=LINELENGTH) :: text
-! ------------------------------------------------------------------------------
     !
     ! -- setup well head table
     if (this%iprhed > 0) then
@@ -4787,17 +4621,13 @@ subroutine maw_setup_tableobj(this)
       call this%headtab%initialize_column(text, 12, alignment=TABCENTER)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_setup_tableobj
 
+  !> @brief Get position of value in connection data
+  !<
   function get_jpos(this, n, j) result(jpos)
-! ******************************************************************************
-! get_jpos -- position of value in connection data.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return variable
     integer(I4B) :: jpos
     ! -- dummy
@@ -4805,22 +4635,17 @@ function get_jpos(this, n, j) result(jpos)
     integer(I4B), intent(in) :: n
     integer(I4B), intent(in) :: j
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- set jpos
     jpos = this%iaconn(n) + j - 1
     !
-    ! -- return
+    ! -- Return
     return
   end function get_jpos
 
+  !> @brief Get the gwfnode for connection
+  !<
   function get_gwfnode(this, n, j) result(igwfnode)
-! ******************************************************************************
-! get_gwfnode -- get the gwfnode for connection.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return variable
     integer(I4B) :: igwfnode
     ! -- dummy
@@ -4829,29 +4654,23 @@ function get_gwfnode(this, n, j) result(igwfnode)
     integer(I4B), intent(in) :: j
     ! -- local
     integer(I4B) :: jpos
-! ------------------------------------------------------------------------------
     !
     ! -- set jpos
     jpos = this%get_jpos(n, j)
     igwfnode = this%gwfnodes(jpos)
     !
-    ! -- return
+    ! -- Return
     return
   end function get_gwfnode
 
+  !> @brief Activate density terms
+  !<
   subroutine maw_activate_density(this)
-! ******************************************************************************
-! maw_activate_density -- Activate addition of density terms
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(MawType), intent(inout) :: this
     ! -- local
     integer(I4B) :: i, j
     ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- Set idense and reallocate denseterms to be of size MAXBOUND
     this%idense = 1
@@ -4865,14 +4684,13 @@ subroutine maw_activate_density(this)
     write (this%iout, '(/1x,a)') 'DENSITY TERMS HAVE BEEN ACTIVATED FOR MAW &
       &PACKAGE: '//trim(adjustl(this%packName))
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_activate_density
 
   !> @brief Activate viscosity terms
-    !!
-    !! Method to activate addition of viscosity terms for a MAW package reach.
-    !!
+  !!
+  !! Method to activate addition of viscosity terms for a MAW package reach.
   !<
   subroutine maw_activate_viscosity(this)
     ! -- modules
@@ -4895,40 +4713,34 @@ subroutine maw_activate_viscosity(this)
     write (this%iout, '(/1x,a)') 'VISCOSITY HAS BEEN ACTIVATED FOR MAW &
       &PACKAGE: '//trim(adjustl(this%packName))
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_activate_viscosity
 
+  !> @brief Calculate the groundwater-maw density exchnage terms
+  !!
+  !! Arguments are as follows:
+  !!     iconn       : maw-gwf connection number
+  !!     hmaw        : maw head
+  !!     hgwf        : gwf head
+  !!     cond        : conductance
+  !!     bmaw        : bottom elevation of this connection
+  !!     flow        : calculated flow, updated here with density terms, + into maw
+  !!     hcofterm    : head coefficient term
+  !!     rhsterm     : right-hand-side value, updated here with density terms
+  !!
+  !! Member variable used here
+  !!     denseterms  : shape (3, MAXBOUND), filled by buoyancy package
+  !!                     col 1 is relative density of maw (densemaw / denseref)
+  !!                     col 2 is relative density of gwf cell (densegwf / denseref)
+  !!                     col 3 is elevation of gwf cell
+  !!
+  !! Upon return, amat and rhs for maw row should be updated as:
+  !!    amat(idiag) = amat(idiag) - hcofterm
+  !!    rhs(n) = rhs(n) + rhsterm
+  !<
   subroutine maw_calculate_density_exchange(this, iconn, hmaw, hgwf, cond, &
                                             bmaw, flow, hcofterm, rhsterm)
-! ******************************************************************************
-! maw_calculate_density_exchange -- Calculate the groundwater-maw density
-!                                   exchange terms.
-!
-! -- Arguments are as follows:
-!     iconn       : maw-gwf connection number
-!     hmaw        : maw head
-!     hgwf        : gwf head
-!     cond        : conductance
-!     bmaw        : bottom elevation of this connection
-!     flow        : calculated flow, updated here with density terms, + into maw
-!     hcofterm    : head coefficient term
-!     rhsterm     : right-hand-side value, updated here with density terms
-!
-! -- Member variable used here
-!     denseterms  : shape (3, MAXBOUND), filled by buoyancy package
-!                     col 1 is relative density of maw (densemaw / denseref)
-!                     col 2 is relative density of gwf cell (densegwf / denseref)
-!                     col 3 is elevation of gwf cell
-!
-! -- Upon return, amat and rhs for maw row should be updated as:
-!    amat(idiag) = amat(idiag) - hcofterm
-!    rhs(n) = rhs(n) + rhsterm
-!
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(MawType), intent(inout) :: this
     integer(I4B), intent(in) :: iconn
@@ -4947,7 +4759,6 @@ subroutine maw_calculate_density_exchange(this, iconn, hmaw, hgwf, cond, &
     real(DP) :: rdenseavg
     real(DP) :: elevavg
     ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- assign relative density terms, return if zero which means not avail yet
     rdensemaw = this%denseterms(1, iconn)
@@ -4988,7 +4799,7 @@ subroutine maw_calculate_density_exchange(this, iconn, hmaw, hgwf, cond, &
       ! -- Flow should be zero so do nothing
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine maw_calculate_density_exchange
 
diff --git a/src/Model/GroundWaterFlow/gwf3mvr8.f90 b/src/Model/GroundWaterFlow/gwf3mvr8.f90
index 842a13dd1b0..5488b31e0e9 100644
--- a/src/Model/GroundWaterFlow/gwf3mvr8.f90
+++ b/src/Model/GroundWaterFlow/gwf3mvr8.f90
@@ -113,7 +113,7 @@ module GwfMvrModule
   use NumericalPackageModule, only: NumericalPackageType
   use BlockParserModule, only: BlockParserType
   use GwfMvrPeriodDataModule, only: GwfMvrPeriodDataType
-  use PackageMoverModule, only: PackageMoverType
+  use PackageMoverModule, only: PackageMoverType, set_packagemover_pointer
   use BaseDisModule, only: DisBaseType
   use InputOutputModule, only: urword
   use TableModule, only: TableType, table_cr
@@ -145,7 +145,9 @@ module GwfMvrModule
     !
     ! -- table objects
     type(TableType), pointer :: outputtab => null()
+
   contains
+    procedure :: mvr_init
     procedure :: mvr_ar
     procedure :: mvr_rp
     procedure :: mvr_ad
@@ -163,23 +165,21 @@ module GwfMvrModule
     procedure :: read_packages
     procedure :: check_packages
     procedure :: assign_packagemovers
+    procedure :: initialize_movers
+    procedure :: fill_budobj
     procedure :: allocate_scalars
     procedure :: allocate_arrays
     procedure, private :: mvr_setup_budobj
-    procedure, private :: mvr_fill_budobj
     procedure, private :: mvr_setup_outputtab
     procedure, private :: mvr_print_outputtab
+
   end type GwfMvrType
 
 contains
 
+  !> @brief Create a new mvr object
+  !<
   subroutine mvr_cr(mvrobj, name_parent, inunit, iout, dis, iexgmvr)
-! ******************************************************************************
-! mvr_cr -- Create a new mvr object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(GwfMvrType), pointer :: mvrobj
     character(len=*), intent(in) :: name_parent
@@ -187,55 +187,62 @@ subroutine mvr_cr(mvrobj, name_parent, inunit, iout, dis, iexgmvr)
     integer(I4B), intent(in) :: iout
     class(DisBaseType), pointer, intent(in) :: dis
     integer(I4B), optional :: iexgmvr
-! ------------------------------------------------------------------------------
     !
     ! -- Create the object
     allocate (mvrobj)
     !
+    ! -- Init
+    call mvrobj%mvr_init(name_parent, inunit, iout, dis, iexgmvr)
+    !
+    ! -- Return
+    return
+  end subroutine mvr_cr
+
+  subroutine mvr_init(this, name_parent, inunit, iout, dis, iexgmvr)
+    class(GwfMvrType) :: this
+    character(len=*), intent(in) :: name_parent
+    integer(I4B), intent(in) :: inunit
+    integer(I4B), intent(in) :: iout
+    class(DisBaseType), pointer, intent(in) :: dis
+    integer(I4B), optional :: iexgmvr
+    !
     ! -- create name and memory paths. name_parent will either be model name or the
     !    exchange name.
-    call mvrobj%set_names(1, name_parent, 'MVR', 'MVR')
+    call this%set_names(1, name_parent, 'MVR', 'MVR')
     !
     ! -- Allocate scalars
-    call mvrobj%allocate_scalars()
+    call this%allocate_scalars()
     !
     ! -- Set pointer to dis
-    mvrobj%dis => dis
+    this%dis => dis
     !
     ! -- Set variables
-    mvrobj%inunit = inunit
-    mvrobj%iout = iout
+    this%inunit = inunit
+    this%iout = iout
     !
     ! -- Set iexgmvr
-    if (present(iexgmvr)) mvrobj%iexgmvr = iexgmvr
+    if (present(iexgmvr)) this%iexgmvr = iexgmvr
     !
     ! -- Create the budget object
     if (inunit > 0) then
-      call budget_cr(mvrobj%budget, mvrobj%memoryPath)
+      call budget_cr(this%budget, this%memoryPath)
       !
       ! -- Initialize block parser
-      call mvrobj%parser%Initialize(mvrobj%inunit, mvrobj%iout)
+      call this%parser%Initialize(this%inunit, this%iout)
     end if
     !
     ! -- instantiate the budget object
-    call budgetobject_cr(mvrobj%budobj, 'WATER MOVER')
+    call budgetobject_cr(this%budobj, 'WATER MOVER')
     !
     ! -- Return
     return
-  end subroutine mvr_cr
+  end subroutine mvr_init
 
+  !> @brief Allocate and read water mover information
+  !<
   subroutine mvr_ar(this)
-! ******************************************************************************
-! mvr_ar -- Allocate and read water mover information
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfMvrType) :: this
-    ! -- locals
-! ------------------------------------------------------------------------------
     !
     ! -- Print a message identifying the water mover package.
     write (this%iout, 1) this%inunit
@@ -267,15 +274,11 @@ subroutine mvr_ar(this)
     return
   end subroutine mvr_ar
 
+  !> @brief Read and Prepare
+  !!
+  !! Read itmp and read new boundaries if itmp > 0
+  !<
   subroutine mvr_rp(this)
-! ******************************************************************************
-! mvr_rp -- Read and Prepare
-! Subroutine: (1) read itmp
-!             (2) read new boundaries if itmp>0
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH
     use TdisModule, only: kper, nper
@@ -297,7 +300,6 @@ subroutine mvr_rp(this)
     character(len=*), parameter :: fmtnbd = &
       "(1X,/1X,'THE NUMBER OF ACTIVE ',A,'S (',I6, &
        &') IS GREATER THAN MAXIMUM(',I6,')')"
-! ------------------------------------------------------------------------------
     !
     ! -- Set ionper to the stress period number for which a new block of data
     !    will be read.
@@ -351,15 +353,10 @@ subroutine mvr_rp(this)
       call this%gwfmvrperioddata%read_from_parser(this%parser, nlist, mname)
       !
       ! -- Process the input data into the individual mover objects
+      call this%initialize_movers(nlist)
+      !
+      ! -- assign the pointers
       do i = 1, nlist
-        call this%mvr(i)%set_values(this%gwfmvrperioddata%mname1(i), &
-                                    this%gwfmvrperioddata%pname1(i), &
-                                    this%gwfmvrperioddata%id1(i), &
-                                    this%gwfmvrperioddata%mname2(i), &
-                                    this%gwfmvrperioddata%pname2(i), &
-                                    this%gwfmvrperioddata%id2(i), &
-                                    this%gwfmvrperioddata%imvrtype(i), &
-                                    this%gwfmvrperioddata%value(i))
         call this%mvr(i)%prepare(this%parser%iuactive, &
                                  this%pckMemPaths, &
                                  this%pakmovers)
@@ -374,16 +371,16 @@ subroutine mvr_rp(this)
       !
       ! -- Check to make sure all providers and receivers are properly stored
       do i = 1, this%nmvr
-        ipos = ifind(this%pckMemPaths, this%mvr(i)%pckNameSrc)
+        ipos = ifind(this%pckMemPaths, this%mvr(i)%mem_path_src)
         if (ipos < 1) then
           write (errmsg, '(a,a,a)') 'Provider ', &
-            trim(this%mvr(i)%pckNameSrc), ' not listed in packages block.'
+            trim(this%mvr(i)%mem_path_src), ' not listed in packages block.'
           call store_error(errmsg)
         end if
-        ipos = ifind(this%pckMemPaths, this%mvr(i)%pckNameTgt)
+        ipos = ifind(this%pckMemPaths, this%mvr(i)%mem_path_tgt)
         if (ipos < 1) then
           write (errmsg, '(a,a,a)') 'Receiver ', &
-            trim(this%mvr(i)%pckNameTgt), ' not listed in packages block.'
+            trim(this%mvr(i)%mem_path_tgt), ' not listed in packages block.'
           call store_error(errmsg)
         end if
       end do
@@ -398,8 +395,8 @@ subroutine mvr_rp(this)
       !
       ! --
       do i = 1, this%nmvr
-        ii = ifind(this%pckMemPaths, this%mvr(i)%pckNameSrc)
-        jj = ifind(this%pckMemPaths, this%mvr(i)%pckNameTgt)
+        ii = ifind(this%pckMemPaths, this%mvr(i)%mem_path_src)
+        jj = ifind(this%pckMemPaths, this%mvr(i)%mem_path_tgt)
         ipos = (ii - 1) * this%maxpackages + jj
         this%ientries(ipos) = this%ientries(ipos) + 1
       end do
@@ -408,23 +405,34 @@ subroutine mvr_rp(this)
       !
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine mvr_rp
 
+  subroutine initialize_movers(this, nr_active_movers)
+    class(GwfMvrType) :: this
+    integer(I4B) :: nr_active_movers
+    ! local
+    integer(I4B) :: i
+
+    do i = 1, nr_active_movers
+      call this%mvr(i)%set_values(this%gwfmvrperioddata%mname1(i), &
+                                  this%gwfmvrperioddata%pname1(i), &
+                                  this%gwfmvrperioddata%id1(i), &
+                                  this%gwfmvrperioddata%mname2(i), &
+                                  this%gwfmvrperioddata%pname2(i), &
+                                  this%gwfmvrperioddata%id2(i), &
+                                  this%gwfmvrperioddata%imvrtype(i), &
+                                  this%gwfmvrperioddata%value(i))
+    end do
+
+  end subroutine initialize_movers
+
   subroutine mvr_ad(this)
-! ******************************************************************************
-! mvr_ad -- Advance mover
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfMvrType) :: this
     ! -- locals
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     do i = 1, this%nmvr
       call this%mvr(i)%advance()
@@ -434,35 +442,23 @@ subroutine mvr_ad(this)
     return
   end subroutine mvr_ad
 
+  !> @brief Calculate qfrommvr as a function of qtomvr
+  !<
   subroutine mvr_fc(this)
-! ******************************************************************************
-! mvr_fc -- Calculate qfrommvr as a function of qtomvr
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    ! -- dummy
     class(GwfMvrType) :: this
-    ! -- locals
+    ! local
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
-    !
+
     do i = 1, this%nmvr
-      call this%mvr(i)%fc()
+      call this%mvr(i)%update_provider()
+      call this%mvr(i)%update_receiver()
     end do
-    !
-    ! -- Return
-    return
+
   end subroutine mvr_fc
 
+  !> @brief Extra convergence check for mover
+  !<
   subroutine mvr_cc(this, innertot, kiter, iend, icnvgmod, cpak, ipak, dpak)
-! ******************************************************************************
-! mvr_cc -- extra convergence check for mover
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfMvrType) :: this
     integer(I4B), intent(in) :: innertot
@@ -472,12 +468,10 @@ subroutine mvr_cc(this, innertot, kiter, iend, icnvgmod, cpak, ipak, dpak)
     character(len=LENPAKLOC), intent(inout) :: cpak
     integer(I4B), intent(inout) :: ipak
     real(DP), intent(inout) :: dpak
-    ! -- local
     ! -- formats
     character(len=*), parameter :: fmtmvrcnvg = &
       "(/,1x,'MOVER PACKAGE REQUIRES AT LEAST TWO OUTER ITERATIONS. CONVERGE &
       &FLAG HAS BEEN RESET TO FALSE.')"
-! ------------------------------------------------------------------------------
     !
     ! -- If there are active movers, then at least 2 outers required
     if (this%nmvr > 0) then
@@ -488,38 +482,40 @@ subroutine mvr_cc(this, innertot, kiter, iend, icnvgmod, cpak, ipak, dpak)
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine mvr_cc
 
+  !> @brief Fill the mover budget object
+  !<
   subroutine mvr_bd(this)
-! ******************************************************************************
-! mvr_bd -- fill the mover budget object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfMvrType) :: this
     ! -- locals
+    integer(I4B) :: i, mapped_id
+    class(PackageMoverType), pointer :: pkg_mvr
     ! -- formats
 ! ------------------------------------------------------------------------------
+    !
+    ! -- set the feature maps
+    allocate (pkg_mvr)
+    do i = 1, this%nmvr
+      call set_packagemover_pointer(pkg_mvr, this%mvr(i)%mem_path_src)
+      mapped_id = pkg_mvr%iprmap(this%mvr(i)%iRchNrSrc)
+      this%mvr(i)%iRchNrSrcMapped = mapped_id
+    end do
+    deallocate (pkg_mvr)
     !
     ! -- fill the budget object
-    call this%mvr_fill_budobj()
+    call this%fill_budobj()
     !
     ! -- Return
     return
   end subroutine mvr_bd
 
+  !> @brief Write mover terms
+  !<
   subroutine mvr_bdsav(this, icbcfl, ibudfl, isuppress_output)
-! ******************************************************************************
-! mvr_bd -- Write mover terms
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: kstp, kper, delt, pertim, totim
     ! -- dummy
@@ -532,7 +528,6 @@ subroutine mvr_bdsav(this, icbcfl, ibudfl, isuppress_output)
     ! -- formats
     character(len=*), parameter :: fmttkk = &
                                    "(1X,/1X,A,'   PERIOD ',I0,'   STEP ',I0)"
-! ------------------------------------------------------------------------------
     !
     ! -- Print the mover flow table
     if (ibudfl /= 0 .and. this%iprflow /= 0 .and. isuppress_output == 0) then
@@ -555,13 +550,9 @@ subroutine mvr_bdsav(this, icbcfl, ibudfl, isuppress_output)
     return
   end subroutine mvr_bdsav
 
+  !> @brief Write mover terms
+  !<
   subroutine mvr_ot_saveflow(this, icbcfl, ibudfl)
-! ******************************************************************************
-! mvr_bd -- Write mover terms
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: kstp, kper, delt, pertim, totim
     ! -- dummy
@@ -570,7 +561,6 @@ subroutine mvr_ot_saveflow(this, icbcfl, ibudfl)
     integer(I4B), intent(in) :: ibudfl
     ! -- locals
     integer(I4B) :: ibinun
-! ------------------------------------------------------------------------------
     !
     ! -- Save the mover flows from the budobj to a mover binary file
     ibinun = 0
@@ -587,20 +577,13 @@ subroutine mvr_ot_saveflow(this, icbcfl, ibudfl)
     return
   end subroutine mvr_ot_saveflow
 
+  !> @brief Print mover flow table
+  !<
   subroutine mvr_ot_printflow(this, icbcfl, ibudfl)
-! ******************************************************************************
-! mvr_ot_printflow -- Print mover flow table
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfMvrType) :: this
     integer(I4B), intent(in) :: icbcfl
     integer(I4B), intent(in) :: ibudfl
-    ! -- locals
-! ------------------------------------------------------------------------------
     !
     ! -- Print the mover flow table
     if (ibudfl /= 0 .and. this%iprflow /= 0) then
@@ -611,13 +594,9 @@ subroutine mvr_ot_printflow(this, icbcfl, ibudfl)
     return
   end subroutine mvr_ot_printflow
 
+  !> @brief Write mover budget to listing file
+  !<
   subroutine mvr_ot_bdsummary(this, ibudfl)
-! ******************************************************************************
-! mvr_ot -- Write mover budget to listing file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: kstp, kper, delt, totim
     use ArrayHandlersModule, only: ifind, expandarray
@@ -628,7 +607,6 @@ subroutine mvr_ot_bdsummary(this, ibudfl)
     character(len=LENMEMPATH) :: pckMemPath
     integer(I4B) :: i, j
     real(DP), allocatable, dimension(:) :: ratin, ratout
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate and initialize ratin/ratout
     allocate (ratin(this%maxpackages), ratout(this%maxpackages))
@@ -640,10 +618,10 @@ subroutine mvr_ot_bdsummary(this, ibudfl)
     ! -- Accumulate the rates
     do i = 1, this%nmvr
       do j = 1, this%maxpackages
-        if (this%pckMemPaths(j) == this%mvr(i)%pckNameSrc) then
+        if (this%pckMemPaths(j) == this%mvr(i)%mem_path_src) then
           ratin(j) = ratin(j) + this%mvr(i)%qpactual
         end if
-        if (this%pckMemPaths(j) == this%mvr(i)%pckNameTgt) then
+        if (this%pckMemPaths(j) == this%mvr(i)%mem_path_tgt) then
           ratout(j) = ratout(j) + this%mvr(i)%qpactual
         end if
       end do
@@ -681,20 +659,14 @@ subroutine mvr_ot_bdsummary(this, ibudfl)
     return
   end subroutine mvr_ot_bdsummary
 
+  !> @brief Deallocate
+  !<
   subroutine mvr_da(this)
-! ******************************************************************************
-! mvr_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DONE
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(GwfMvrType) :: this
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- Arrays
     if (this%inunit > 0) then
@@ -743,13 +715,9 @@ subroutine mvr_da(this)
     return
   end subroutine mvr_da
 
+  !> @brief Read options specified in the input options block
+  !<
   subroutine read_options(this)
-! ******************************************************************************
-! read_options
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH, DZERO, DONE
     use OpenSpecModule, only: access, form
@@ -766,7 +734,6 @@ subroutine read_options(this)
     character(len=*), parameter :: fmtmvrbin = &
       "(4x, 'MVR ', 1x, a, 1x, ' WILL BE SAVED TO FILE: ', a, /4x, 'OPENED ON &
       &UNIT: ', I0)"
-! ------------------------------------------------------------------------------
     !
     ! -- get options block
     call this%parser%GetBlock('OPTIONS', isfound, ierr, &
@@ -838,13 +805,9 @@ subroutine read_options(this)
     return
   end subroutine read_options
 
+  !> @brief Check MODELNAMES option set correctly
+  !<
   subroutine check_options(this)
-! ******************************************************************************
-! check_options
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error, store_error_unit
@@ -852,8 +815,6 @@ subroutine check_options(this)
     class(GwfMvrType) :: this
     ! -- local
     character(len=LINELENGTH) :: errmsg
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- Check if not exchange mover but model names are specified
     if (this%iexgmvr == 0 .and. this%imodelnames == 1) then
@@ -877,13 +838,9 @@ subroutine check_options(this)
     return
   end subroutine check_options
 
+  !> @brief Read the dimensions for this package
+  !<
   subroutine read_dimensions(this)
-! ******************************************************************************
-! read_dimensions -- Read the dimensions for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error, count_errors, store_error_unit
@@ -895,8 +852,6 @@ subroutine read_dimensions(this)
     logical :: isfound, endOfBlock
     integer(I4B) :: i
     integer(I4B) :: j
-    ! -- format
-! ------------------------------------------------------------------------------
     !
     ! -- get dimensions block
     call this%parser%GetBlock('DIMENSIONS', isfound, ierr, &
@@ -951,17 +906,13 @@ subroutine read_dimensions(this)
       call this%parser%StoreErrorUnit()
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine read_dimensions
 
+  !> @brief Read the packages that will be managed by this mover
+  !<
   subroutine read_packages(this)
-! ******************************************************************************
-! read_packages -- Read the packages that will be managed by this mover
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH
     use MemoryHelperModule, only: create_mem_path
@@ -973,8 +924,6 @@ subroutine read_packages(this)
     integer(I4B) :: lloc, ierr
     integer(I4B) :: npak
     logical :: isfound, endOfBlock
-    ! -- format
-! ------------------------------------------------------------------------------
     !
     ! -- get packages block
     call this%parser%GetBlock('PACKAGES', isfound, ierr, &
@@ -998,9 +947,8 @@ subroutine read_packages(this)
           this%pckMemPaths(npak) = create_mem_path(this%name_model, word1)
           word = word1
         else
-          this%pckMemPaths(npak) = trim(word1)
           call this%parser%GetStringCaps(word2)
-          this%pckMemPaths(npak) = create_mem_path(this%pckMemPaths(npak), word2)
+          this%pckMemPaths(npak) = create_mem_path(word1, word2)
           word = word2
         end if
         this%paknames(npak) = trim(word)
@@ -1022,17 +970,13 @@ subroutine read_packages(this)
       call this%parser%StoreErrorUnit()
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine read_packages
 
+  !> @brief Check to make sure packages have mover activated
+  !<
   subroutine check_packages(this)
-! ******************************************************************************
-! check_packages -- check to make sure packages have mover activated
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH
     use MemoryManagerModule, only: mem_setptr
@@ -1043,8 +987,6 @@ subroutine check_packages(this)
     character(len=LINELENGTH) :: errmsg
     integer(I4B) :: i
     integer(I4B), pointer :: imover_ptr
-    ! -- format
-! ------------------------------------------------------------------------------
     !
     ! -- Check to make sure mover is activated for each package
     do i = 1, size(this%pckMemPaths)
@@ -1064,25 +1006,19 @@ subroutine check_packages(this)
       call this%parser%StoreErrorUnit()
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine check_packages
 
+  !> @brief Assign pointer to each package's packagemover object
+  !<
   subroutine assign_packagemovers(this)
-! ******************************************************************************
-! assign_packagemovers -- assign pointer to each package's packagemover object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use PackageMoverModule, only: set_packagemover_pointer
     ! -- dummy
     class(GwfMvrType), intent(inout) :: this
     ! -- local
     integer(I4B) :: i
-    ! -- format
-! ------------------------------------------------------------------------------
     !
     ! -- Assign the package mover pointer if it hasn't been assigned yet
     do i = 1, size(this%pckMemPaths)
@@ -1092,24 +1028,18 @@ subroutine assign_packagemovers(this)
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine assign_packagemovers
 
+  !> @brief Allocate package scalars
+  !<
   subroutine allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DONE
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwfMvrType) :: this
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- allocate scalars in NumericalPackageType
     call this%NumericalPackageType%allocate_scalars()
@@ -1141,13 +1071,9 @@ subroutine allocate_scalars(this)
     return
   end subroutine allocate_scalars
 
+  !> @brief Allocate package arrays
+  !<
   subroutine allocate_arrays(this)
-! ******************************************************************************
-! allocate_arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     use ConstantsModule, only: DZERO
@@ -1156,7 +1082,6 @@ subroutine allocate_arrays(this)
     class(GwfMvrType) :: this
     ! -- local
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate
     allocate (this%mvr(this%maxmvr))
@@ -1188,13 +1113,9 @@ subroutine allocate_arrays(this)
     return
   end subroutine allocate_arrays
 
+  !> @brief Set up the budget object that stores all the mvr flows
+  !<
   subroutine mvr_setup_budobj(this)
-! ******************************************************************************
-! mvr_setup_budobj -- Set up the budget object that stores all the mvr flows
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LENBUDTXT
     use MemoryHelperModule, only: split_mem_path
@@ -1211,7 +1132,6 @@ subroutine mvr_setup_budobj(this)
     integer(I4B) :: maxlist
     integer(I4B) :: idx
     character(len=LENBUDTXT) :: text
-! ------------------------------------------------------------------------------
     !
     ! -- Determine the number of mover budget terms. These are fixed for
     !    the simulation and cannot change.  A separate term is required
@@ -1253,11 +1173,11 @@ subroutine mvr_setup_budobj(this)
       end do
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine mvr_setup_budobj
 
-  subroutine mvr_fill_budobj(this)
+  subroutine fill_budobj(this)
 ! ******************************************************************************
 ! mvr_fill_budobj -- copy flow terms into this%budobj
 ! ******************************************************************************
@@ -1283,8 +1203,6 @@ subroutine mvr_fill_budobj(this)
     character(len=LENPACKAGENAME) :: packagename1, packagename2
     character(len=LENMEMPATH) :: pckMemPathsDummy
     real(DP) :: q
-    ! -- formats
-! -----------------------------------------------------------------------------
     !
     ! -- initialize counter
     idx = 0
@@ -1321,15 +1239,14 @@ subroutine mvr_fill_budobj(this)
           !
           ! -- pname1 is provider, pname2 is receiver
           !    flow is always negative because it is coming from provider
-          if (this%pckMemPaths(i) == this%mvr(n)%pckNameSrc) then
-            if (this%pckMemPaths(j) == this%mvr(n)%pckNameTgt) then
+          if (this%pckMemPaths(i) == this%mvr(n)%mem_path_src) then
+            if (this%pckMemPaths(j) == this%mvr(n)%mem_path_tgt) then
               !
               ! -- set q to qpactual
               q = -this%mvr(n)%qpactual
               !
-              ! -- map from irch1 to feature (needed for lake to map outlet to lake number)
-              n1 = this%mvr(n)%iRchNrSrc
-              n1 = this%pakmovers(i)%iprmap(n1)
+              ! -- use mapped index (needed for lake to map outlet to lake number)
+              n1 = this%mvr(n)%iRchNrSrcMapped
               !
               ! -- set receiver id to irch2
               n2 = this%mvr(n)%iRchNrTgt
@@ -1345,17 +1262,13 @@ subroutine mvr_fill_budobj(this)
     ! --Terms are filled, now accumulate them for this time step
     call this%budobj%accumulate_terms()
     !
-    ! -- return
+    ! -- Return
     return
-  end subroutine mvr_fill_budobj
+  end subroutine fill_budobj
 
+  !> @brief Set up output table
+  !<
   subroutine mvr_setup_outputtab(this)
-! ******************************************************************************
-! mvr_setup_outputtab -- set up output table
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfMvrType), intent(inout) :: this
     ! -- local
@@ -1363,7 +1276,6 @@ subroutine mvr_setup_outputtab(this)
     character(len=LINELENGTH) :: text
     integer(I4B) :: ntabcol
     integer(I4B) :: ilen
-! ------------------------------------------------------------------------------
     !
     ! -- allocate and initialize the output table
     if (this%iprflow /= 0) then
@@ -1393,20 +1305,16 @@ subroutine mvr_setup_outputtab(this)
       call this%outputtab%initialize_column(text, ilen)
       text = 'RECEIVER ID'
       call this%outputtab%initialize_column(text, 10)
-
+      !
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine mvr_setup_outputtab
 
+  !> @brief Set up output table
+  !<
   subroutine mvr_print_outputtab(this)
-! ******************************************************************************
-! mvr_setup_outputtab -- set up output table
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- module
     use TdisModule, only: kstp, kper
     ! -- dummy
@@ -1414,7 +1322,6 @@ subroutine mvr_print_outputtab(this)
     ! -- local
     character(len=LINELENGTH) :: title
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     ! -- set table kstp and kper
     call this%outputtab%set_kstpkper(kstp, kper)
@@ -1426,15 +1333,15 @@ subroutine mvr_print_outputtab(this)
     call this%outputtab%set_maxbound(this%nmvr)
     do i = 1, this%nmvr
       call this%outputtab%add_term(i)
-      call this%outputtab%add_term(this%mvr(i)%pckNameSrc)
+      call this%outputtab%add_term(this%mvr(i)%mem_path_src)
       call this%outputtab%add_term(this%mvr(i)%iRchNrSrc)
       call this%outputtab%add_term(this%mvr(i)%qavailable)
       call this%outputtab%add_term(this%mvr(i)%qpactual)
-      call this%outputtab%add_term(this%mvr(i)%pckNameTgt)
+      call this%outputtab%add_term(this%mvr(i)%mem_path_tgt)
       call this%outputtab%add_term(this%mvr(i)%iRchNrTgt)
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine mvr_print_outputtab
 
diff --git a/src/Model/GroundWaterFlow/gwf3npf8.f90 b/src/Model/GroundWaterFlow/gwf3npf8.f90
index fd60dd91cc2..e02a183b87c 100644
--- a/src/Model/GroundWaterFlow/gwf3npf8.f90
+++ b/src/Model/GroundWaterFlow/gwf3npf8.f90
@@ -1,5 +1,6 @@
 module GwfNpfModule
   use KindModule, only: DP, I4B
+  use SimVariablesModule, only: errmsg
   use ConstantsModule, only: DZERO, DEM9, DEM8, DEM7, DEM6, DEM2, &
                              DHALF, DP9, DONE, DTWO, &
                              DLNLOW, DLNHIGH, &
@@ -102,8 +103,9 @@ module GwfNpfModule
     integer(I4B), pointer :: kchangeper => null() ! last stress period in which any node K (or K22, or K33) values were changed (0 if unchanged from start of simulation)
     integer(I4B), pointer :: kchangestp => null() ! last time step in which any node K (or K22, or K33) values were changed (0 if unchanged from start of simulation)
     integer(I4B), dimension(:), pointer, contiguous :: nodekchange => null() ! grid array of flags indicating for each node whether its K (or K22, or K33) value changed (1) at (kchangeper, kchangestp) or not (0)
-    !
+
   contains
+
     procedure :: npf_df
     procedure :: npf_ac
     procedure :: npf_mc
@@ -143,18 +145,15 @@ module GwfNpfModule
     procedure, public :: increase_edge_count
     procedure, public :: set_edge_properties
     procedure, public :: calcSatThickness
+
   end type
 
 contains
 
+  !> @brief Create a new NPF object. Pass a inunit value of 0 if npf data will
+  !! initialized from memory
+  !<
   subroutine npf_cr(npfobj, name_model, input_mempath, inunit, iout)
-! ******************************************************************************
-! npf_cr -- Create a new NPF object. Pass a inunit value of 0 if npf data will
-!           initialized from memory
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use KindModule, only: LGP
     use MemoryManagerExtModule, only: mem_set_value
@@ -164,32 +163,24 @@ subroutine npf_cr(npfobj, name_model, input_mempath, inunit, iout)
     character(len=*), intent(in) :: input_mempath
     integer(I4B), intent(in) :: inunit
     integer(I4B), intent(in) :: iout
-    ! -- locals
-    logical(LGP) :: found_fname
     ! -- formats
     character(len=*), parameter :: fmtheader = &
       "(1x, /1x, 'NPF -- NODE PROPERTY FLOW PACKAGE, VERSION 1, 3/30/2015', &
        &' INPUT READ FROM MEMPATH: ', A, /)"
-! ------------------------------------------------------------------------------
     !
     ! -- Create the object
     allocate (npfobj)
     !
     ! -- create name and memory path
-    call npfobj%set_names(1, name_model, 'NPF', 'NPF')
+    call npfobj%set_names(1, name_model, 'NPF', 'NPF', input_mempath)
     !
     ! -- Allocate scalars
     call npfobj%allocate_scalars()
     !
     ! -- Set variables
-    npfobj%input_mempath = input_mempath
     npfobj%inunit = inunit
     npfobj%iout = iout
     !
-    ! -- set name of input file
-    call mem_set_value(npfobj%input_fname, 'INPUT_FNAME', npfobj%input_mempath, &
-                       found_fname)
-    !
     ! -- check if npf is enabled
     if (inunit > 0) then
       !
@@ -201,7 +192,7 @@ subroutine npf_cr(npfobj, name_model, input_mempath, inunit, iout)
     return
   end subroutine npf_cr
 
-  !> @brief define the NPF package instance
+  !> @brief Define the NPF package instance
   !!
   !! This is a hybrid routine: it either reads the options for this package
   !! from the input file, or the optional argument @param npf_options
@@ -209,12 +200,6 @@ end subroutine npf_cr
   !! xt3d_df is called, when enabled.
   !<
   subroutine npf_df(this, dis, xt3d, ingnc, invsc, npf_options)
-! ******************************************************************************
-! npf_df -- Define
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SimModule, only: store_error
     use Xt3dModule, only: xt3d_cr
@@ -225,9 +210,6 @@ subroutine npf_df(this, dis, xt3d, ingnc, invsc, npf_options)
     integer(I4B), intent(in) :: ingnc !< ghostnodes enabled? (>0 means yes)
     integer(I4B), intent(in) :: invsc !< viscosity enabled? (>0 means yes)
     type(GwfNpfOptionsType), optional, intent(in) :: npf_options !< the optional options, for when not constructing from file
-    ! -- local
-    ! -- data
-! ------------------------------------------------------------------------------
     !
     ! -- Set a pointer to dis
     this%dis => dis
@@ -252,7 +234,7 @@ subroutine npf_df(this, dis, xt3d, ingnc, invsc, npf_options)
       ! -- allocate arrays
       call this%allocate_arrays(this%dis%nodes, this%dis%njas)
     end if
-
+    !
     call this%check_options()
     !
     ! -- Save pointer to xt3d object
@@ -271,21 +253,15 @@ subroutine npf_df(this, dis, xt3d, ingnc, invsc, npf_options)
     return
   end subroutine npf_df
 
+  !> @brief Add connections for extended neighbors to the sparse matrix
+  !<
   subroutine npf_ac(this, moffset, sparse)
-! ******************************************************************************
-! npf_ac -- Add connections for extended neighbors to the sparse matrix
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SparseModule, only: sparsematrix
     ! -- dummy
     class(GwfNpftype) :: this
     integer(I4B), intent(in) :: moffset
     type(sparsematrix), intent(inout) :: sparse
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- Add extended neighbors (neighbors of neighbors)
     if (this%ixt3d /= 0) call this%xt3d%xt3d_ac(moffset, sparse)
@@ -294,20 +270,13 @@ subroutine npf_ac(this, moffset, sparse)
     return
   end subroutine npf_ac
 
+  !> @brief Map connections and construct iax, jax, and idxglox
+  !<
   subroutine npf_mc(this, moffset, matrix_sln)
-! ******************************************************************************
-! npf_mc -- Map connections and construct iax, jax, and idxglox
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfNpftype) :: this
     integer(I4B), intent(in) :: moffset
     class(MatrixBaseType), pointer :: matrix_sln
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     if (this%ixt3d /= 0) call this%xt3d%xt3d_mc(moffset, matrix_sln)
     !
@@ -315,18 +284,12 @@ subroutine npf_mc(this, moffset, matrix_sln)
     return
   end subroutine npf_mc
 
-  !> @brief allocate and read this NPF instance
+  !> @brief Allocate and read this NPF instance
   !!
   !! Allocate remaining package arrays, preprocess the input data and
   !! call *_ar on xt3d, when active.
   !<
   subroutine npf_ar(this, ic, vsc, ibound, hnew)
-! ******************************************************************************
-! npf_ar -- Allocate and Read
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_reallocate
     ! -- dummy
@@ -337,9 +300,6 @@ subroutine npf_ar(this, ic, vsc, ibound, hnew)
     real(DP), dimension(:), pointer, contiguous, intent(inout) :: hnew !< pointer to model head array
     ! -- local
     integer(I4B) :: n
-    ! -- formats
-    ! -- data
-! ------------------------------------------------------------------------------
     !
     ! -- Store pointers to arguments that were passed in
     this%ic => ic
@@ -361,7 +321,6 @@ subroutine npf_ar(this, ic, vsc, ibound, hnew)
     if (this%invsc /= 0) then
       this%vsc => vsc
     end if
-
     !
     ! -- allocate arrays to store original user input in case TVK/VSC modify them
     if (this%invsc > 0) then
@@ -403,10 +362,10 @@ end subroutine npf_ar
   !> @brief Read and prepare method for package
   !!
   !! Read and prepare NPF stress period data.
-  !!
   !<
   subroutine npf_rp(this)
     implicit none
+    ! -- dummy
     class(GwfNpfType) :: this
     !
     ! -- TVK
@@ -414,27 +373,27 @@ subroutine npf_rp(this)
       call this%tvk%rp()
     end if
     !
+    ! -- Return
     return
   end subroutine npf_rp
 
+  !> @brief Advance
+  !!
+  !! Sets hold (head old) to bot whenever a wettable cell is dry
+  !<
   subroutine npf_ad(this, nodes, hold, hnew, irestore)
-! ******************************************************************************
-! npf_ad -- Advance
-! Subroutine (1) Sets hold to bot whenever a wettable cell is dry
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use TdisModule, only: kper, kstp
     !
     implicit none
+    ! -- dummy
     class(GwfNpfType) :: this
     integer(I4B), intent(in) :: nodes
     real(DP), dimension(nodes), intent(inout) :: hold
     real(DP), dimension(nodes), intent(inout) :: hnew
     integer(I4B), intent(in) :: irestore
+    ! -- local
     integer(I4B) :: n
-! ------------------------------------------------------------------------------
     !
     ! -- loop through all cells and set hold=bot if wettable cell is dry
     if (this%irewet > 0) then
@@ -487,13 +446,9 @@ subroutine npf_ad(this, nodes, hold, hnew, irestore)
     return
   end subroutine npf_ad
 
+  !> @brief Routines associated fill coefficients
+  !<
   subroutine npf_cf(this, kiter, nodes, hnew)
-! ******************************************************************************
-! npf_cf -- Formulate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfNpfType) :: this
     integer(I4B) :: kiter
@@ -502,7 +457,6 @@ subroutine npf_cf(this, kiter, nodes, hnew)
     ! -- local
     integer(I4B) :: n
     real(DP) :: satn
-! ------------------------------------------------------------------------------
     !
     ! -- Perform wetting and drying
     if (this%inewton /= 1) then
@@ -525,13 +479,9 @@ subroutine npf_cf(this, kiter, nodes, hnew)
     return
   end subroutine npf_cf
 
+  !> @brief Formulate coefficients
+  !<
   subroutine npf_fc(this, kiter, matrix_sln, idxglo, rhs, hnew)
-! ******************************************************************************
-! npf_fc -- Formulate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DONE
     ! -- dummy
@@ -546,7 +496,6 @@ subroutine npf_fc(this, kiter, matrix_sln, idxglo, rhs, hnew)
     integer(I4B) :: isymcon, idiagm
     real(DP) :: hyn, hym
     real(DP) :: cond
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate conductance and put into amat
     !
@@ -639,13 +588,9 @@ subroutine npf_fc(this, kiter, matrix_sln, idxglo, rhs, hnew)
     return
   end subroutine npf_fc
 
+  !> @brief Fill newton terms
+  !<
   subroutine npf_fn(this, kiter, matrix_sln, idxglo, rhs, hnew)
-! ******************************************************************************
-! npf_fn -- Fill newton terms
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfNpfType) :: this
     integer(I4B) :: kiter
@@ -670,10 +615,8 @@ subroutine npf_fn(this, kiter, matrix_sln, idxglo, rhs, hnew)
     real(DP) :: botup
     real(DP) :: topdn
     real(DP) :: botdn
-! ------------------------------------------------------------------------------
     !
     ! -- add newton terms to solution matrix
-    !
     nodes = this%dis%nodes
     nja = this%dis%con%nja
     if (this%ixt3d /= 0) then
@@ -784,16 +727,12 @@ subroutine npf_fn(this, kiter, matrix_sln, idxglo, rhs, hnew)
     return
   end subroutine npf_fn
 
+  !> @brief Under-relaxation
+  !!
+  !! Under-relaxation of Groundwater Flow Model Heads for current outer
+  !! iteration using the cell bottoms at the bottom of the model
+  !<
   subroutine npf_nur(this, neqmod, x, xtemp, dx, inewtonur, dxmax, locmax)
-! ******************************************************************************
-! bnd_nur -- under-relaxation
-! Subroutine: (1) Under-relaxation of Groundwater Flow Model Heads for current
-!                 outer iteration using the cell bottoms at the bottom of the
-!                 model
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfNpfType) :: this
     integer(I4B), intent(in) :: neqmod
@@ -808,8 +747,6 @@ subroutine npf_nur(this, neqmod, x, xtemp, dx, inewtonur, dxmax, locmax)
     real(DP) :: botm
     real(DP) :: xx
     real(DP) :: dxx
-! ------------------------------------------------------------------------------
-
     !
     ! -- Newton-Raphson under-relaxation
     do n = 1, this%dis%nodes
@@ -832,17 +769,13 @@ subroutine npf_nur(this, neqmod, x, xtemp, dx, inewtonur, dxmax, locmax)
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine npf_nur
 
+  !> @brief Calculate flowja
+  !<
   subroutine npf_cq(this, hnew, flowja)
-! ******************************************************************************
-! npf_cq -- Calculate flowja
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfNpfType) :: this
     real(DP), intent(inout), dimension(:) :: hnew
@@ -850,7 +783,6 @@ subroutine npf_cq(this, hnew, flowja)
     ! -- local
     integer(I4B) :: n, ipos, m
     real(DP) :: qnm
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate the flow across each cell face and store in flowja
     !
@@ -874,19 +806,14 @@ subroutine npf_cq(this, hnew, flowja)
     return
   end subroutine npf_cq
 
+  !> @brief Fractional cell saturation
+  !<
   subroutine sgwf_npf_thksat(this, n, hn, thksat)
-! ******************************************************************************
-! sgwf_npf_thksat -- Fractional cell saturation
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfNpfType) :: this
     integer(I4B), intent(in) :: n
     real(DP), intent(in) :: hn
     real(DP), intent(inout) :: thksat
-! ------------------------------------------------------------------------------
     !
     ! -- Standard Formulation
     if (hn >= this%dis%top(n)) then
@@ -906,13 +833,9 @@ subroutine sgwf_npf_thksat(this, n, hn, thksat)
     return
   end subroutine sgwf_npf_thksat
 
+  !> @brief Flow between two cells
+  !<
   subroutine sgwf_npf_qcalc(this, n, m, hn, hm, icon, qnm)
-! ******************************************************************************
-! sgwf_npf_qcalc -- Flow between two cells
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfNpfType) :: this
     integer(I4B), intent(in) :: n
@@ -926,7 +849,6 @@ subroutine sgwf_npf_qcalc(this, n, m, hn, hm, icon, qnm)
     real(DP) :: condnm
     real(DP) :: hntemp, hmtemp
     integer(I4B) :: ihc
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize
     ihc = this%dis%con%ihc(this%dis%con%jas(icon))
@@ -986,13 +908,9 @@ subroutine sgwf_npf_qcalc(this, n, m, hn, hm, icon, qnm)
     return
   end subroutine sgwf_npf_qcalc
 
+  !> @brief Record flowja and calculate specific discharge if requested
+  !<
   subroutine npf_save_model_flows(this, flowja, icbcfl, icbcun)
-! ******************************************************************************
-! npf_save_model_flows -- Record flowja and calculate specific discharge if requested
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfNpfType) :: this
     real(DP), dimension(:), intent(in) :: flowja
@@ -1000,9 +918,6 @@ subroutine npf_save_model_flows(this, flowja, icbcfl, icbcun)
     integer(I4B), intent(in) :: icbcun
     ! -- local
     integer(I4B) :: ibinun
-    !data
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- Set unit number for binary output
     if (this%ipakcb < 0) then
@@ -1033,13 +948,9 @@ subroutine npf_save_model_flows(this, flowja, icbcfl, icbcun)
     return
   end subroutine npf_save_model_flows
 
+  !> @brief Print budget
+  !<
   subroutine npf_print_model_flows(this, ibudfl, flowja)
-! ******************************************************************************
-! npf_ot -- Budget
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: kper, kstp
     use ConstantsModule, only: LENBIGLINE
@@ -1055,7 +966,6 @@ subroutine npf_print_model_flows(this, ibudfl, flowja)
     ! -- formats
     character(len=*), parameter :: fmtiprflow = &
       &"(/,4x,'CALCULATED INTERCELL FLOW FOR PERIOD ', i0, ' STEP ', i0)"
-! ------------------------------------------------------------------------------
     !
     ! -- Write flowja to list file if requested
     if (ibudfl /= 0 .and. this%iprflow > 0) then
@@ -1080,19 +990,14 @@ subroutine npf_print_model_flows(this, ibudfl, flowja)
     return
   end subroutine npf_print_model_flows
 
+  !> @brief Deallocate variables
+  !<
   subroutine npf_da(this)
-! ******************************************************************************
-! npf_da -- Deallocate variables
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerExtModule, only: memorylist_remove
     use SimVariablesModule, only: idm_context
     ! -- dummy
     class(GwfNpftype) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Deallocate input memory
     call memorylist_remove(this%name_model, 'NPF', idm_context)
@@ -1182,14 +1087,12 @@ end subroutine npf_da
   !!
   !! Allocate and initialize scalars for the VSC package. The base model
   !! allocate scalars method is also called.
-  !!
   !<
   subroutine allocate_scalars(this)
     ! -- modules
     use MemoryHelperModule, only: create_mem_path
     ! -- dummy
     class(GwfNpftype) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- allocate scalars in NumericalPackageType
     call this%NumericalPackageType%allocate_scalars()
@@ -1284,14 +1187,12 @@ end subroutine allocate_scalars
   !> @ brief Store backup copy of hydraulic conductivity when the VSC
   !!         package is activate
   !!
-  !! The K arrays (K11, etc.) get multiplied by the viscosity ratio
-  !! so that subsequent uses of K already take into account the effect
-  !! of viscosity. Thus the original user-specified K array values are
-  !! lost unless they are backed up in k11input, for example.  In a new
-  !! stress period/time step, the values in k11input are multiplied by
-  !! the viscosity ratio, not k11 since it contains viscosity-adjusted
-  !! hydraulic conductivity values.
-  !!
+  !! The K arrays (K11, etc.) get multiplied by the viscosity ratio so that
+  !! subsequent uses of K already take into account the effect of viscosity.
+  !! Thus the original user-specified K array values are lost unless they are
+  !! backed up in k11input, for example.  In a new stress period/time step,
+  !! the values in k11input are multiplied by the viscosity ratio, not k11
+  !! since it contains viscosity-adjusted hydraulic conductivity values.
   !<
   subroutine store_original_k_arrays(this, ncells, njas)
     ! -- modules
@@ -1302,7 +1203,6 @@ subroutine store_original_k_arrays(this, ncells, njas)
     integer(I4B), intent(in) :: njas
     ! -- local
     integer(I4B) :: n
-! ------------------------------------------------------------------------------
     !
     ! -- Retain copy of user-specified K arrays
     do n = 1, ncells
@@ -1315,21 +1215,15 @@ subroutine store_original_k_arrays(this, ncells, njas)
     return
   end subroutine store_original_k_arrays
 
+  !> @brief Allocate npf arrays
+  !<
   subroutine allocate_arrays(this, ncells, njas)
-! ******************************************************************************
-! allocate_arrays -- Allocate npf arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfNpftype) :: this
     integer(I4B), intent(in) :: ncells
     integer(I4B), intent(in) :: njas
     ! -- local
     integer(I4B) :: n
-! ------------------------------------------------------------------------------
     !
     call mem_allocate(this%ithickstartflag, ncells, 'ITHICKSTARTFLAG', &
                       this%memoryPath)
@@ -1379,17 +1273,13 @@ subroutine allocate_arrays(this, ncells, njas)
                   '                  WETDRY', '                  ANGLE1', &
                   '                  ANGLE2', '                  ANGLE3']
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine allocate_arrays
 
+  !> @brief Log npf options sourced from the input mempath
+  !<
   subroutine log_options(this, found)
-! ******************************************************************************
-! log_options -- log npf options sourced from the input mempath
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use KindModule, only: LGP
     use GwfNpfInputModule, only: GwfNpfParamFoundType
@@ -1397,7 +1287,6 @@ subroutine log_options(this, found)
     class(GwfNpftype) :: this
     ! -- locals
     type(GwfNpfParamFoundType), intent(in) :: found
-! ------------------------------------------------------------------------------
     !
     write (this%iout, '(1x,a)') 'Setting NPF Options'
     if (found%iprflow) &
@@ -1464,19 +1353,21 @@ subroutine log_options(this, found)
       write (this%iout, '(4x,a,i5)') &
       'Head rewet equation (IHDWET) has been set to: ', this%ihdwet
     write (this%iout, '(1x,a,/)') 'End Setting NPF Options'
-
+    !
+    ! -- Return
+    return
   end subroutine log_options
 
+  !> @brief Update simulation options from input mempath
+  !<
   subroutine source_options(this)
-! ******************************************************************************
-! source_options -- update simulation options from input mempath
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
+    use SimModule, only: store_error, store_error_filename
+    use MemoryManagerModule, only: mem_setptr, get_isize
     use MemoryManagerExtModule, only: mem_set_value
+    use CharacterStringModule, only: CharacterStringType
     use GwfNpfInputModule, only: GwfNpfParamFoundType
+    use SourceCommonModule, only: filein_fname
     ! -- dummy
     class(GwfNpftype) :: this
     ! -- locals
@@ -1484,7 +1375,6 @@ subroutine source_options(this)
       &[character(len=LENVARNAME) :: 'LOGARITHMIC', 'AMT-LMK', 'AMT-HMK']
     type(GwfNpfParamFoundType) :: found
     character(len=LINELENGTH) :: tvk6_filename
-! ------------------------------------------------------------------------------
     !
     ! -- update defaults with idm sourced values
     call mem_set_value(this%iprflow, 'IPRFLOW', this%input_mempath, found%iprflow)
@@ -1508,8 +1398,6 @@ subroutine source_options(this)
                        found%ik22overk)
     call mem_set_value(this%ik33overk, 'IK33OVERK', this%input_mempath, &
                        found%ik33overk)
-    call mem_set_value(tvk6_filename, 'TVK6_FILENAME', this%input_mempath, &
-                       found%tvk6_filename)
     call mem_set_value(this%inewton, 'INEWTON', this%input_mempath, found%inewton)
     call mem_set_value(this%iusgnrhc, 'IUSGNRHC', this%input_mempath, &
                        found%iusgnrhc)
@@ -1531,19 +1419,19 @@ subroutine source_options(this)
     ! -- save specific discharge active
     if (found%isavspdis) this%icalcspdis = this%isavspdis
     !
-    ! -- TVK6 subpackage file spec provided
-    if (found%tvk6_filename) then
-      this%intvk = GetUnit()
-      call openfile(this%intvk, this%iout, tvk6_filename, 'TVK')
-      call tvk_cr(this%tvk, this%name_model, this%intvk, this%iout)
-    end if
-    !
     ! -- no newton specified
     if (found%inewton) then
       this%inewton = 0
       this%iasym = 0
     end if
     !
+    ! -- enforce 0 or 1 TVK6_FILENAME entries in option block
+    if (filein_fname(tvk6_filename, 'TVK6_FILENAME', this%input_mempath, &
+                     this%input_fname)) then
+      call openfile(this%intvk, this%iout, tvk6_filename, 'TVK')
+      call tvk_cr(this%tvk, this%name_model, this%intvk, this%iout)
+    end if
+    !
     ! -- log options
     if (this%iout > 0) then
       call this%log_options(found)
@@ -1553,10 +1441,13 @@ subroutine source_options(this)
     return
   end subroutine source_options
 
+  !> @brief Set options in the NPF object
+  !<
   subroutine set_options(this, options)
+    ! -- dummy
     class(GwfNpftype) :: this
     type(GwfNpfOptionsType), intent(in) :: options
-
+    !
     this%icellavg = options%icellavg
     this%ithickstrt = options%ithickstrt
     this%iperched = options%iperched
@@ -1566,24 +1457,20 @@ subroutine set_options(this, options)
     this%wetfct = options%wetfct
     this%iwetit = options%iwetit
     this%ihdwet = options%ihdwet
-
+    !
+    ! -- Return
+    return
   end subroutine set_options
 
+  !> @brief Check for conflicting NPF options
+  !<
   subroutine check_options(this)
-! ******************************************************************************
-! check_options -- Check for conflicting NPF options
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SimModule, only: store_error, count_errors, store_error_filename
     use ConstantsModule, only: LINELENGTH
     ! -- dummy
     class(GwfNpftype) :: this
-    ! -- local
-    character(len=LINELENGTH) :: errmsg
-! ------------------------------------------------------------------------------
+    !
     ! -- check if this%iusgnrhc has been enabled for a model that is not using
     !    the Newton-Raphson formulation
     if (this%iusgnrhc > 0 .and. this%inewton == 0) then
@@ -1684,59 +1571,59 @@ end subroutine check_options
   !> @brief Write dimensions to list file
   !<
   subroutine log_griddata(this, found)
+    ! -- modules
     use GwfNpfInputModule, only: GwfNpfParamFoundType
+    ! -- dummy
     class(GwfNpfType) :: this
     type(GwfNpfParamFoundType), intent(in) :: found
-
+    !
     write (this%iout, '(1x,a)') 'Setting NPF Griddata'
-
+    !
     if (found%icelltype) then
       write (this%iout, '(4x,a)') 'ICELLTYPE set from input file'
     end if
-
+    !
     if (found%k) then
       write (this%iout, '(4x,a)') 'K set from input file'
     end if
-
+    !
     if (found%k33) then
       write (this%iout, '(4x,a)') 'K33 set from input file'
     else
       write (this%iout, '(4x,a)') 'K33 not provided.  Setting K33 = K.'
     end if
-
+    !
     if (found%k22) then
       write (this%iout, '(4x,a)') 'K22 set from input file'
     else
       write (this%iout, '(4x,a)') 'K22 not provided.  Setting K22 = K.'
     end if
-
+    !
     if (found%wetdry) then
       write (this%iout, '(4x,a)') 'WETDRY set from input file'
     end if
-
+    !
     if (found%angle1) then
       write (this%iout, '(4x,a)') 'ANGLE1 set from input file'
     end if
-
+    !
     if (found%angle2) then
       write (this%iout, '(4x,a)') 'ANGLE2 set from input file'
     end if
-
+    !
     if (found%angle3) then
       write (this%iout, '(4x,a)') 'ANGLE3 set from input file'
     end if
-
+    !
     write (this%iout, '(1x,a,/)') 'End Setting NPF Griddata'
-
+    !
+    ! -- Return
+    return
   end subroutine log_griddata
 
+  !> @brief Update simulation griddata from input mempath
+  !<
   subroutine source_griddata(this)
-! ******************************************************************************
-! source_griddata -- update simulation griddata from input mempath
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SimModule, only: count_errors, store_error
     use MemoryManagerModule, only: mem_reallocate
@@ -1749,8 +1636,6 @@ subroutine source_griddata(this)
     type(GwfNpfParamFoundType) :: found
     logical, dimension(2) :: afound
     integer(I4B), dimension(:), pointer, contiguous :: map
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- set map to convert user input data into reduced data
     map => null()
@@ -1828,13 +1713,10 @@ subroutine source_griddata(this)
     return
   end subroutine source_griddata
 
+  !> @brief Initialize and check NPF data
+  !<
   subroutine prepcheck(this)
-! ******************************************************************************
-! prepcheck -- Initialize and check NPF data
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use ConstantsModule, only: LINELENGTH, DPIO180
     use SimModule, only: store_error, count_errors, store_error_filename
     ! -- dummy
@@ -1848,7 +1730,6 @@ subroutine prepcheck(this)
       &"(1x, 'Hydraulic property ',a,' is <= 0 for cell ',a, ' ', 1pg15.6)"
     character(len=*), parameter :: fmtkerr2 = &
       &"(1x, '... ', i0,' additional errors not shown for ',a)"
-! ------------------------------------------------------------------------------
     !
     ! -- initialize
     aname => this%aname
@@ -1983,7 +1864,8 @@ subroutine prepcheck(this)
     if (count_errors() > 0) then
       call store_error_filename(this%input_fname)
     end if
-
+    !
+    ! -- Return
     return
   end subroutine prepcheck
 
@@ -1998,10 +1880,12 @@ end subroutine prepcheck
   !! 5. If NEWTON under-relaxation, determine lower most node
   !<
   subroutine preprocess_input(this)
+    ! -- modules
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error, count_errors, store_error_filename
+    ! -- dummy
     class(GwfNpfType) :: this !< the instance of the NPF package
-    ! local
+    ! -- local
     integer(I4B) :: n, m, ii, nn
     real(DP) :: hyn, hym
     real(DP) :: satn, topn, botn
@@ -2009,7 +1893,7 @@ subroutine preprocess_input(this)
     real(DP) :: minbot, botm
     logical :: finished
     character(len=LINELENGTH) :: cellstr, errmsg
-    ! format strings
+    ! -- format
     character(len=*), parameter :: fmtcnv = &
       "(1X,'CELL ', A, &
       &' ELIMINATED BECAUSE ALL HYDRAULIC CONDUCTIVITIES TO NODE ARE 0.')"
@@ -2193,14 +2077,12 @@ subroutine preprocess_input(this)
     !
     ! -- Return
     return
-
   end subroutine preprocess_input
 
   !> @brief Calculate CONDSAT array entries for the given node
   !!
   !! Calculate saturated conductances for all connections of the given node,
   !! or optionally for the upper portion of the matrix only.
-  !!
   !<
   subroutine calc_condsat(this, node, upperOnly)
     ! -- dummy variables
@@ -2290,6 +2172,7 @@ subroutine calc_condsat(this, node, upperOnly)
       this%condsat(jj) = csat
     end do
     !
+    ! -- Return
     return
   end subroutine calc_condsat
 
@@ -2304,7 +2187,7 @@ function calc_initial_sat(this, n) result(satn)
     ! -- dummy variables
     class(GwfNpfType) :: this
     integer(I4B), intent(in) :: n
-    ! -- return
+    ! -- Return
     real(DP) :: satn
     !
     satn = DONE
@@ -2315,13 +2198,9 @@ function calc_initial_sat(this, n) result(satn)
     return
   end function calc_initial_sat
 
+  !> @brief Perform wetting and drying
+  !<
   subroutine sgwf_npf_wetdry(this, kiter, hnew)
-! ******************************************************************************
-! sgwf_npf_wetdry -- Perform wetting and drying
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: kstp, kper
     use SimModule, only: store_error, store_error_filename
@@ -2351,7 +2230,7 @@ subroutine sgwf_npf_wetdry(this, kiter, hnew)
       &"(1X,/1X,'CONSTANT-HEAD CELL WENT DRY -- SIMULATION ABORTED')"
     character(len=*), parameter :: fmtni = &
       &"(1X,'CELLID=',a,' ITERATION=',I0,' TIME STEP=',I0,' STRESS PERIOD=',I0)"
-! ------------------------------------------------------------------------------
+    !
     ! -- Initialize
     ncnvrt = 0
     ihdcnv = 0
@@ -2394,7 +2273,6 @@ subroutine sgwf_npf_wetdry(this, kiter, hnew)
       thck = ttop - bbot
       !
       ! -- If thck<0 print message, set hnew, and ibound
-!      if(thck<0) then
       if (thck <= DZERO) then
         call this%wdmsg(1, ncnvrt, nodcnvrt, acnvrt, ihdcnv, kiter, n)
         hnew(n) = this%hdry
@@ -2424,18 +2302,14 @@ subroutine sgwf_npf_wetdry(this, kiter, hnew)
     return
   end subroutine sgwf_npf_wetdry
 
+  !> @brief Determine if a cell should rewet
+  !!
+  !! This method can be called from any external object that has a head that
+  !! can be used to rewet the GWF cell node.  The ihc value is used to
+  !! determine if it is a vertical or horizontal connection, which can operate
+  !! differently depending on user settings.
+  !<
   subroutine rewet_check(this, kiter, node, hm, ibdm, ihc, hnew, irewet)
-! ******************************************************************************
-! rewet_check -- Determine if a cell should rewet.  This method can
-!   be called from any external object that has a head that can be used to
-!   rewet the GWF cell node.  The ihc value is used to determine if it is a
-!   vertical or horizontal connection, which can operate differently depending
-!   on user settings.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfNpfType) :: this
     integer(I4B), intent(in) :: kiter
@@ -2448,8 +2322,6 @@ subroutine rewet_check(this, kiter, node, hm, ibdm, ihc, hnew, irewet)
     ! -- local
     integer(I4B) :: itflg
     real(DP) :: wd, awd, turnon, bbot
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     irewet = 0
     !
@@ -2498,14 +2370,10 @@ subroutine rewet_check(this, kiter, node, hm, ibdm, ihc, hnew, irewet)
     return
   end subroutine rewet_check
 
+  !> @brief Print wet/dry message
+  !<
   subroutine sgwf_npf_wdmsg(this, icode, ncnvrt, nodcnvrt, acnvrt, ihdcnv, &
                             kiter, n)
-! ******************************************************************************
-! sgwf_npf_wdmsg -- Print wet/dry message
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: kstp, kper
     ! -- dummy
@@ -2524,7 +2392,7 @@ subroutine sgwf_npf_wdmsg(this, icode, ncnvrt, nodcnvrt, acnvrt, ihdcnv, &
       "(1X,/1X,'CELL CONVERSIONS FOR ITER.=',I0, &
        &'  STEP=',I0,'  PERIOD=',I0,'   (NODE or LRC)')"
     character(len=*), parameter :: fmtnode = "(1X,3X,5(A4, A20))"
-! ------------------------------------------------------------------------------
+    !
     ! -- Keep track of cell conversions
     if (icode > 0) then
       ncnvrt = ncnvrt + 1
@@ -2550,22 +2418,17 @@ subroutine sgwf_npf_wdmsg(this, icode, ncnvrt, nodcnvrt, acnvrt, ihdcnv, &
     return
   end subroutine sgwf_npf_wdmsg
 
+  !> @brief Calculate the effective hydraulic conductivity for the n-m connection
+  !!
+  !! n is primary node node number
+  !! m is connected node (not used if vg is provided)
+  !! ihc is horizontal indicator (0 vertical, 1 horizontal, 2 vertically
+  !!   staggered)
+  !! ipos_opt is position of connection in ja array
+  !! vg is the global unit vector that expresses the direction from which to
+  !!   calculate an effective hydraulic conductivity.
+  !<
   function hy_eff(this, n, m, ihc, ipos, vg) result(hy)
-! ******************************************************************************
-! hy_eff -- Calculate the effective hydraulic conductivity for the n-m
-!   connection.
-!     n is primary node node number
-!     m is connected node (not used if vg is provided)
-!     ihc is horizontal indicator (0 vertical, 1 horizontal, 2 vertically
-!       staggered)
-!     ipos_opt is position of connection in ja array
-!     vg is the global unit vector that expresses the direction from which to
-!       calculate an effective hydraulic conductivity.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- return
     real(DP) :: hy
     ! -- dummy
@@ -2580,8 +2443,6 @@ function hy_eff(this, n, m, ihc, ipos, vg) result(hy)
     real(DP) :: hy11, hy22, hy33
     real(DP) :: ang1, ang2, ang3
     real(DP) :: vg1, vg2, vg3
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize
     iipos = 0
@@ -2647,22 +2508,19 @@ function hy_eff(this, n, m, ihc, ipos, vg) result(hy)
     return
   end function hy_eff
 
+  !> @brief Horizontal conductance between two cells
+  !!
+  !! inwtup: if 1, then upstream-weight condsat, otherwise recalculate
+  !!
+  !! This function uses a weighted transmissivity in the harmonic mean
+  !! conductance calculations. This differs from the MODFLOW-NWT and
+  !! MODFLOW-USG conductance calculations for the Newton-Raphson formulation
+  !! which use a weighted hydraulic conductivity.
+  !<
   function hcond(ibdn, ibdm, ictn, ictm, inewton, inwtup, ihc, icellavg, iusg, &
                  iupw, condsat, hn, hm, satn, satm, hkn, hkm, topn, topm, &
                  botn, botm, cln, clm, fawidth, satomega, satminopt) &
     result(condnm)
-! ******************************************************************************
-! hcond -- Horizontal conductance between two cells
-!   inwtup: if 1, then upstream-weight condsat, otherwise recalculate
-!
-! hcond function uses a weighted transmissivity in the harmonic mean
-! conductance calculations. This differs from the MODFLOW-NWT and MODFLOW-USG
-! conductance calculations for the Newton-Raphson formulation which use a
-! weighted hydraulic conductivity.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: condnm
     ! -- dummy
@@ -2704,7 +2562,7 @@ function hcond(ibdn, ibdm, ictn, ictm, inewton, inwtup, ihc, icellavg, iusg, &
     real(DP) :: top, bot
     real(DP) :: athk
     real(DP) :: afac
-! ------------------------------------------------------------------------------
+    !
     if (present(satminopt)) then
       satmin = satminopt
     else
@@ -2752,7 +2610,7 @@ function hcond(ibdn, ibdm, ictn, ictm, inewton, inwtup, ihc, icellavg, iusg, &
           sn = sQuadraticSaturation(topn, botn, hn, satomega, satmin)
           sm = sQuadraticSaturation(topm, botm, hm, satomega, satmin)
         end if
-
+        !
         if (hn > hm) then
           condnm = sn
         else
@@ -2793,7 +2651,7 @@ function hcond(ibdn, ibdm, ictn, ictm, inewton, inwtup, ihc, icellavg, iusg, &
           thksatn = max(min(tpn, sill_top) - sill_bot, DZERO)
           thksatm = max(min(tpm, sill_top) - sill_bot, DZERO)
         end if
-
+        !
         athk = DONE
         if (iusg == 1) then
           if (ihc == 2) then
@@ -2814,15 +2672,11 @@ function hcond(ibdn, ibdm, ictn, ictm, inewton, inwtup, ihc, icellavg, iusg, &
     return
   end function hcond
 
+  !> @brief Vertical conductance between two cells
+  !<
   function vcond(ibdn, ibdm, ictn, ictm, inewton, ivarcv, idewatcv, &
                  condsat, hn, hm, vkn, vkm, satn, satm, topn, topm, botn, &
                  botm, flowarea) result(condnm)
-! ******************************************************************************
-! vcond -- Vertical conductance between two cells
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: condnm
     ! -- dummy
@@ -2850,7 +2704,6 @@ function vcond(ibdn, ibdm, ictn, ictm, inewton, ivarcv, idewatcv, &
     real(DP) :: bovk1
     real(DP) :: bovk2
     real(DP) :: denom
-! ------------------------------------------------------------------------------
     !
     ! -- If either n or m is inactive then conductance is zero
     if (ibdn == 0 .or. ibdm == 0) then
@@ -2900,30 +2753,26 @@ function vcond(ibdn, ibdm, ictn, ictm, inewton, ivarcv, idewatcv, &
     return
   end function vcond
 
+  !> @brief Calculate the conductance between two cells
+  !!
+  !! k1 is hydraulic conductivity for cell 1 (in the direction of cell2)
+  !! k2 is hydraulic conductivity for cell 2 (in the direction of cell1)
+  !! thick1 is the saturated thickness for cell 1
+  !! thick2 is the saturated thickness for cell 2
+  !! cl1 is the distance from the center of cell1 to the shared face with cell2
+  !! cl2 is the distance from the center of cell2 to the shared face with cell1
+  !! h1 is the head for cell1
+  !! h2 is the head for cell2
+  !! width is the width perpendicular to flow
+  !! iavgmeth is the averaging method:
+  !!   0 is harmonic averaging
+  !!   1 is logarithmic averaging
+  !!   2 is arithmetic averaging of sat thickness and logarithmic averaging of
+  !!     hydraulic conductivity
+  !!   3 is arithmetic averaging of sat thickness and harmonic averaging of
+  !!     hydraulic conductivity
+  !<
   function condmean(k1, k2, thick1, thick2, cl1, cl2, width, iavgmeth)
-! ******************************************************************************
-! condmean -- Calculate the conductance between two cells
-!
-!   k1 is hydraulic conductivity for cell 1 (in the direction of cell2)
-!   k2 is hydraulic conductivity for cell 2 (in the direction of cell1)
-!   thick1 is the saturated thickness for cell 1
-!   thick2 is the saturated thickness for cell 2
-!   cl1 is the distance from the center of cell1 to the shared face with cell2
-!   cl2 is the distance from the center of cell2 to the shared face with cell1
-!   h1 is the head for cell1
-!   h2 is the head for cell2
-!   width is the width perpendicular to flow
-!   iavgmeth is the averaging method:
-!     0 is harmonic averaging
-!     1 is logarithmic averaging
-!     2 is arithmetic averaging of sat thickness and logarithmic averaging of
-!       hydraulic conductivity
-!     3 is arithmetic averaging of sat thickness and harmonic averaging of
-!       hydraulic conductivity
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: condmean
     ! -- dummy
@@ -2939,7 +2788,6 @@ function condmean(k1, k2, thick1, thick2, cl1, cl2, width, iavgmeth)
     real(DP) :: t1
     real(DP) :: t2
     real(DP) :: tmean, kmean, denom
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize
     t1 = k1 * thick1
@@ -2990,14 +2838,11 @@ function condmean(k1, k2, thick1, thick2, cl1, cl2, width, iavgmeth)
     return
   end function condmean
 
+  !> @brief Calculate the the logarithmic mean of two double precision numbers
+  !!
+  !! Use an approximation if the ratio is near 1
+  !<
   function logmean(d1, d2)
-! ******************************************************************************
-! logmean -- Calculate the the logarithmic mean of two double precision
-!            numbers.  Use an approximation if the ratio is near 1.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: logmean
     ! -- dummy
@@ -3005,7 +2850,6 @@ function logmean(d1, d2)
     real(DP), intent(in) :: d2
     ! -- local
     real(DP) :: drat
-! ------------------------------------------------------------------------------
     !
     drat = d2 / d1
     if (drat <= DLNLOW .or. drat >= DLNHIGH) then
@@ -3018,31 +2862,28 @@ function logmean(d1, d2)
     return
   end function logmean
 
+  !> @brief Calculate the effective horizontal hydraulic conductivity from an
+  !! ellipse using a specified direction (unit vector vg1, vg2, vg3)
+  !!
+  !! k11 is the hydraulic conductivity of the major ellipse axis
+  !! k22 is the hydraulic conductivity of first minor axis
+  !! k33 is the hydraulic conductivity of the second minor axis
+  !! ang1 is the counter-clockwise rotation (radians) of the ellipse in
+  !!   the (x, y) plane
+  !! ang2 is the rotation of the conductivity ellipsoid upward or
+  !!   downward from the (x, y) plane
+  !! ang3 is the rotation of the conductivity ellipsoid about the major
+  !!   axis
+  !! vg1, vg2, and vg3 are the components of a unit vector in model coordinates
+  !!   in the direction of the connection between cell n and m
+  !!iavgmeth is the averaging method.  If zero, then use harmonic averaging.
+  !!   if one, then use arithmetic averaging.
+  !<
   function hyeff_calc(k11, k22, k33, ang1, ang2, ang3, vg1, vg2, vg3, &
                       iavgmeth) result(hyeff)
-! ******************************************************************************
-! hyeff_calc -- Calculate the effective horizontal hydraulic conductivity from
-!   an ellipse using a specified direction (unit vector vg1, vg2, vg3).
-!   k11 is the hydraulic conductivity of the major ellipse axis
-!   k22 is the hydraulic conductivity of first minor axis
-!   k33 is the hydraulic conductivity of the second minor axis
-!   ang1 is the counter-clockwise rotation (radians) of the ellipse in
-!     the (x, y) plane
-!   ang2 is the rotation of the conductivity ellipsoid upward or
-!     downward from the (x, y) plane
-!   ang3 is the rotation of the conductivity ellipsoid about the major
-!     axis
-!   vg1, vg2, and vg3 are the components of a unit vector in model coordinates
-!     in the direction of the connection between cell n and m
-!  iavgmeth is the averaging method.  If zero, then use harmonic averaging.
-!     if one, then use arithmetic averaging.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DONE
-    ! -- result
+    ! -- return
     real(DP) :: hyeff
     ! -- dummy
     real(DP), intent(in) :: k11
@@ -3060,7 +2901,6 @@ function hyeff_calc(k11, k22, k33, ang1, ang2, ang3, vg1, vg2, vg3, &
     real(DP), dimension(3, 3) :: r
     real(DP) :: ve1, ve2, ve3
     real(DP) :: denom, dnum, d1, d2, d3
-! ------------------------------------------------------------------------------
     !
     ! -- Sin and cos of angles
     s1 = sin(ang1)
@@ -3124,14 +2964,9 @@ function hyeff_calc(k11, k22, k33, ang1, ang2, ang3, vg1, vg2, vg3, &
     return
   end function hyeff_calc
 
+  !> @brief Calculate the 3 conmponents of specific discharge at the cell center
+  !<
   subroutine calc_spdis(this, flowja)
-! ******************************************************************************
-! calc_spdis -- Calculate the 3 conmponents of specific discharge
-!     at the cell center.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SimModule, only: store_error
     ! -- dummy
@@ -3181,7 +3016,6 @@ subroutine calc_spdis(this, flowja)
     real(DP), allocatable, dimension(:) :: bix
     real(DP), allocatable, dimension(:) :: biy
     logical :: nozee = .true.
-! ------------------------------------------------------------------------------
     !
     ! -- Ensure dis has necessary information
     if (this%icalcspdis /= 0 .and. this%dis%con%ianglex == 0) then
@@ -3423,18 +3257,13 @@ subroutine calc_spdis(this, flowja)
     deallocate (bix)
     deallocate (biy)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine calc_spdis
 
+  !> @brief Save specific discharge in binary format to ibinun
+  !<
   subroutine sav_spdis(this, ibinun)
-! ******************************************************************************
-! sav_spdis -- save specific discharge in binary format to ibinun
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfNpfType) :: this
     integer(I4B), intent(in) :: ibinun
@@ -3443,7 +3272,6 @@ subroutine sav_spdis(this, ibinun)
     character(len=16), dimension(3) :: auxtxt
     integer(I4B) :: n
     integer(I4B) :: naux
-! ------------------------------------------------------------------------------
     !
     ! -- Write the header
     text = '      DATA-SPDIS'
@@ -3460,18 +3288,13 @@ subroutine sav_spdis(this, ibinun)
                                           this%spdis(:, n))
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine sav_spdis
 
+  !> @brief Save saturation in binary format to ibinun
+  !<
   subroutine sav_sat(this, ibinun)
-! ******************************************************************************
-! sav_sat -- save saturation in binary format to ibinun
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfNpfType) :: this
     integer(I4B), intent(in) :: ibinun
@@ -3481,7 +3304,6 @@ subroutine sav_sat(this, ibinun)
     real(DP), dimension(1) :: a
     integer(I4B) :: n
     integer(I4B) :: naux
-! ------------------------------------------------------------------------------
     !
     ! -- Write the header
     text = '        DATA-SAT'
@@ -3498,41 +3320,30 @@ subroutine sav_sat(this, ibinun)
       call this%dis%record_mf6_list_entry(ibinun, n, n, DZERO, naux, a)
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine sav_sat
 
+  !> @brief Reserve space for nedges cells that have an edge on them.
+  !!
+  !! This must be called before the npf%allocate_arrays routine, which is
+  !! called from npf%ar.
+  !<
   subroutine increase_edge_count(this, nedges)
-! ******************************************************************************
-! increase_edge_count -- reserve space for nedges cells that have an edge on them.
-!   This must be called before the npf%allocate_arrays routine, which is called
-!   from npf%ar.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfNpfType) :: this
     integer(I4B), intent(in) :: nedges
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     this%nedges = this%nedges + nedges
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine increase_edge_count
 
+  !> @brief Provide the npf package with edge properties
+  !<
   subroutine set_edge_properties(this, nodedge, ihcedge, q, area, nx, ny, &
                                  distance)
-! ******************************************************************************
-! edge_count -- provide the npf package with edge properties.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(GwfNpfType) :: this
     integer(I4B), intent(in) :: nodedge
@@ -3544,7 +3355,6 @@ subroutine set_edge_properties(this, nodedge, ihcedge, q, area, nx, ny, &
     real(DP), intent(in) :: distance
     ! -- local
     integer(I4B) :: lastedge
-! ------------------------------------------------------------------------------
     !
     this%lastedge = this%lastedge + 1
     lastedge = this%lastedge
@@ -3560,19 +3370,21 @@ subroutine set_edge_properties(this, nodedge, ihcedge, q, area, nx, ny, &
     !    edge properties assignment loop, so need to reset lastedge to 0
     if (this%lastedge == this%nedges) this%lastedge = 0
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine set_edge_properties
 
   !> Calculate saturated thickness between cell n and m
   !<
   function calcSatThickness(this, n, m, ihc) result(satThickness)
+    ! -- dummy
     class(GwfNpfType) :: this !< this NPF instance
     integer(I4B) :: n !< node n
     integer(I4B) :: m !< node m
     integer(I4B) :: ihc !< 1 = horizonal connection, 0 for vertical
+    ! -- return
     real(DP) :: satThickness !< saturated thickness
-
+    !
     satThickness = thksatnm(this%ibound(n), &
                             this%ibound(m), &
                             this%icelltype(n), &
@@ -3590,19 +3402,16 @@ function calcSatThickness(this, n, m, ihc) result(satThickness)
                             this%dis%bot(m), &
                             this%satomega, &
                             this%satmin)
-
+    !
+    ! -- Return
+    return
   end function calcSatThickness
 
+  !> @brief Calculate saturated thickness at interface between two cells
+  !<
   function thksatnm(ibdn, ibdm, ictn, ictm, inwtup, ihc, iusg, &
                     hn, hm, satn, satm, topn, topm, botn, botm, &
                     satomega, satminopt) result(res)
-! ******************************************************************************
-! thksatnm -- calculate saturated thickness at interface between two cells
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- return
     real(DP) :: res
     ! -- dummy
@@ -3633,7 +3442,7 @@ function thksatnm(ibdn, ibdm, ictn, ictm, inwtup, ihc, iusg, &
     real(DP) :: sill_top, sill_bot
     real(DP) :: tpn, tpm
     real(DP) :: top, bot
-! ------------------------------------------------------------------------------
+    !
     if (present(satminopt)) then
       satmin = satminopt
     else
diff --git a/src/Model/GroundWaterFlow/gwf3npf8idm.f90 b/src/Model/GroundWaterFlow/gwf3npf8idm.f90
index 79fe5bee186..b4e7f4e7ac2 100644
--- a/src/Model/GroundWaterFlow/gwf3npf8idm.f90
+++ b/src/Model/GroundWaterFlow/gwf3npf8idm.f90
@@ -1,5 +1,6 @@
 ! ** Do Not Modify! MODFLOW 6 system generated file. **
 module GwfNpfInputModule
+  use ConstantsModule, only: LENVARNAME
   use InputDefinitionModule, only: InputParamDefinitionType, &
                                    InputBlockDefinitionType
   private
@@ -64,7 +65,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -80,7 +82,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -96,7 +99,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -112,7 +116,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -128,7 +133,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -144,7 +150,8 @@ module GwfNpfInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -160,7 +167,8 @@ module GwfNpfInputModule
     .false., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -176,7 +184,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -192,7 +201,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -208,7 +218,8 @@ module GwfNpfInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -224,7 +235,8 @@ module GwfNpfInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -240,7 +252,8 @@ module GwfNpfInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -256,7 +269,8 @@ module GwfNpfInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -272,7 +286,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -288,7 +303,8 @@ module GwfNpfInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -304,7 +320,8 @@ module GwfNpfInputModule
     .false., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -320,7 +337,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -336,7 +354,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -352,7 +371,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -368,7 +388,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -384,7 +405,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -400,7 +422,8 @@ module GwfNpfInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -416,7 +439,8 @@ module GwfNpfInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -432,7 +456,8 @@ module GwfNpfInputModule
     .true., & ! required
     .true., & ! multi-record
     .true., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -448,7 +473,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -464,7 +490,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -480,7 +507,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -496,7 +524,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -512,7 +541,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -528,7 +558,8 @@ module GwfNpfInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -544,7 +575,8 @@ module GwfNpfInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -560,7 +592,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -576,7 +609,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -592,7 +626,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -608,7 +643,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -624,7 +660,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -640,7 +677,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -700,7 +738,8 @@ module GwfNpfInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     ) &
     ]
 
diff --git a/src/Model/GroundWaterFlow/gwf3obs8.f90 b/src/Model/GroundWaterFlow/gwf3obs8.f90
index 15490abbcbf..e15ec7c8f57 100644
--- a/src/Model/GroundWaterFlow/gwf3obs8.f90
+++ b/src/Model/GroundWaterFlow/gwf3obs8.f90
@@ -18,7 +18,9 @@ module GwfObsModule
     type(GwfIcType), pointer, private :: ic => null() ! initial conditions
     real(DP), dimension(:), pointer, contiguous, private :: x => null() ! head
     real(DP), dimension(:), pointer, contiguous, private :: flowja => null() ! intercell flows
+
   contains
+
     ! -- Public procedures
     procedure, public :: gwf_obs_ar
     procedure, public :: obs_bd => gwf_obs_bd
@@ -31,20 +33,14 @@ module GwfObsModule
 
 contains
 
+  !> @brief Create a new GwfObsType object
+  !!
+  !! Create oseration object, allocate pointers, initialize values
+  !<
   subroutine gwf_obs_cr(obs, inobs)
-! ******************************************************************************
-! gwf_obs_cr -- Create a new GwfObsType object
-! Subroutine: (1) creates object
-!             (2) allocates pointers
-!             (3) initializes values
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(GwfObsType), pointer, intent(out) :: obs
     integer(I4B), pointer, intent(in) :: inobs
-! ------------------------------------------------------------------------------
     !
     allocate (obs)
     call obs%allocate_scalars()
@@ -52,22 +48,18 @@ subroutine gwf_obs_cr(obs, inobs)
     obs%inputFilename = ''
     obs%inUnitObs => inobs
     !
+    ! -- Return
     return
   end subroutine gwf_obs_cr
 
+  !> @brief Allocate and read
+  !<
   subroutine gwf_obs_ar(this, ic, x, flowja)
-! ******************************************************************************
-! gwf_obs_ar -- allocate and read
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfObsType), intent(inout) :: this
     type(GwfIcType), pointer, intent(in) :: ic
     real(DP), dimension(:), pointer, contiguous, intent(in) :: x
     real(DP), dimension(:), pointer, contiguous, intent(in) :: flowja
-! ------------------------------------------------------------------------------
     !
     ! Call ar method of parent class
     call this%obs_ar()
@@ -75,16 +67,13 @@ subroutine gwf_obs_ar(this, ic, x, flowja)
     ! set pointers
     call this%set_pointers(ic, x, flowja)
     !
+    ! -- Return
     return
   end subroutine gwf_obs_ar
 
+  !> @brief Define
+  !<
   subroutine gwf_obs_df(this, iout, pkgname, filtyp, dis)
-! ******************************************************************************
-! gwt_obs_df -- define
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfObsType), intent(inout) :: this
     integer(I4B), intent(in) :: iout
@@ -93,7 +82,6 @@ subroutine gwf_obs_df(this, iout, pkgname, filtyp, dis)
     class(DisBaseType), pointer :: dis
     ! -- local
     integer(I4B) :: indx
-! ------------------------------------------------------------------------------
     !
     ! Call overridden method of parent class
     call this%ObsType%obs_df(iout, pkgname, filtyp, dis)
@@ -113,16 +101,13 @@ subroutine gwf_obs_df(this, iout, pkgname, filtyp, dis)
     call this%StoreObsType('flow-ja-face', .true., indx)
     this%obsData(indx)%ProcessIdPtr => gwf_process_intercell_obs_id
     !
+    ! -- Return
     return
   end subroutine gwf_obs_df
 
+  !> @brief Save obs
+  !<
   subroutine gwf_obs_bd(this)
-! ******************************************************************************
-! gwf_obs_bd -- save obs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfObsType), intent(inout) :: this
     ! -- local
@@ -130,7 +115,6 @@ subroutine gwf_obs_bd(this)
     real(DP) :: v
     character(len=100) :: msg
     class(ObserveType), pointer :: obsrv => null()
-! ------------------------------------------------------------------------------
     !
     call this%obs_bd_clear()
     !
@@ -160,49 +144,40 @@ subroutine gwf_obs_bd(this)
       end if
     end if
     !
+    ! -- Return
     return
   end subroutine gwf_obs_bd
 
+  !> @brief Do GWF observations need any checking? If so, add checks here
+  !<
   subroutine gwf_obs_rp(this)
-! ******************************************************************************
-! gwf_obs_rp
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     class(GwfObsType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
     ! Do GWF observations need any checking? If so, add checks here
+    !
+    ! -- Return
     return
   end subroutine gwf_obs_rp
 
+  !> @brief Deallocate memory
+  !<
   subroutine gwf_obs_da(this)
-! ******************************************************************************
-! gwf_obs_da
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfObsType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
     nullify (this%ic)
     nullify (this%x)
     nullify (this%flowja)
     call this%ObsType%obs_da()
     !
+    ! -- Return
     return
   end subroutine gwf_obs_da
 
+  !> @brief Set pointers
+  !<
   subroutine set_pointers(this, ic, x, flowja)
-! ******************************************************************************
-! set_pointers
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwfObsType), intent(inout) :: this
     type(GwfIcType), pointer, intent(in) :: ic
@@ -213,18 +188,15 @@ subroutine set_pointers(this, ic, x, flowja)
     this%x => x
     this%flowja => flowja
     !
+    ! -- Return
     return
   end subroutine set_pointers
 
   ! -- Procedures related to GWF observations (NOT type-bound)
 
+  !> @brief Calculate drawdown obseration when requested
+  !<
   subroutine gwf_process_head_drawdown_obs_id(obsrv, dis, inunitobs, iout)
-! ******************************************************************************
-! gwf_process_head_drawdown_obs_id
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(ObserveType), intent(inout) :: obsrv
     class(DisBaseType), intent(in) :: dis
@@ -234,7 +206,6 @@ subroutine gwf_process_head_drawdown_obs_id(obsrv, dis, inunitobs, iout)
     integer(I4B) :: nn1
     integer(I4B) :: icol, istart, istop
     character(len=LINELENGTH) :: ermsg, strng
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize variables
     strng = obsrv%IDstring
@@ -253,16 +224,13 @@ subroutine gwf_process_head_drawdown_obs_id(obsrv, dis, inunitobs, iout)
       call store_error_unit(inunitobs)
     end if
     !
+    ! -- Return
     return
   end subroutine gwf_process_head_drawdown_obs_id
 
+  !> @brief Process flow between two cells when requested
+  !<
   subroutine gwf_process_intercell_obs_id(obsrv, dis, inunitobs, iout)
-! ******************************************************************************
-! gwf_process_intercell_obs_id
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(ObserveType), intent(inout) :: obsrv
     class(DisBaseType), intent(in) :: dis
@@ -274,7 +242,6 @@ subroutine gwf_process_intercell_obs_id(obsrv, dis, inunitobs, iout)
     character(len=LINELENGTH) :: ermsg, strng
     ! formats
 70  format('Error: No connection exists between cells identified in text: ', a)
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize variables
     strng = obsrv%IDstring
@@ -315,6 +282,7 @@ subroutine gwf_process_intercell_obs_id(obsrv, dis, inunitobs, iout)
       call store_error_unit(inunitobs)
     end if
     !
+    ! -- Return
     return
   end subroutine gwf_process_intercell_obs_id
 
diff --git a/src/Model/GroundWaterFlow/gwf3oc8.f90 b/src/Model/GroundWaterFlow/gwf3oc8.f90
index 12e635b7963..03485adc738 100644
--- a/src/Model/GroundWaterFlow/gwf3oc8.f90
+++ b/src/Model/GroundWaterFlow/gwf3oc8.f90
@@ -59,7 +59,7 @@ end subroutine oc_cr
   !<
   subroutine oc_ar(this, head, dis, dnodata)
     ! -- dummy
-    class(GwfOcType) :: this !< GwtOcType object
+    class(GwfOcType) :: this !< GwfOcType object
     real(DP), dimension(:), pointer, contiguous, intent(in) :: head !< model head
     class(DisBaseType), pointer, intent(in) :: dis !< model discretization package
     real(DP), intent(in) :: dnodata !< no data value
diff --git a/src/Model/GroundWaterFlow/gwf3rch8.f90 b/src/Model/GroundWaterFlow/gwf3rch8.f90
index e50ad4f279b..40920754da9 100644
--- a/src/Model/GroundWaterFlow/gwf3rch8.f90
+++ b/src/Model/GroundWaterFlow/gwf3rch8.f90
@@ -1,18 +1,19 @@
 module RchModule
   !
-  use KindModule, only: DP, I4B
+  use KindModule, only: DP, I4B, LGP
   use ConstantsModule, only: DZERO, LENFTYPE, LENPACKAGENAME, MAXCHARLEN, &
-                             IWETLAKE
+                             IWETLAKE, LINELENGTH
   use MemoryHelperModule, only: create_mem_path
   use BndModule, only: BndType
-  use SimModule, only: store_error, store_error_unit
+  use BndExtModule, only: BndExtType
+  use SimModule, only: store_error, store_error_filename
   use SimVariablesModule, only: errmsg
   use ObsModule, only: DefaultObsIdProcessor
   use TimeArraySeriesLinkModule, only: TimeArraySeriesLinkType
-  use TimeSeriesLinkModule, only: TimeSeriesLinkType, &
-                                  GetTimeSeriesLinkFromList
   use BlockParserModule, only: BlockParserType
+  use CharacterStringModule, only: CharacterStringType
   use MatrixBaseModule
+  use GeomUtilModule, only: get_node
   !
   implicit none
   !
@@ -23,42 +24,42 @@ module RchModule
   character(len=LENPACKAGENAME) :: text = '             RCH'
   character(len=LENPACKAGENAME) :: texta = '            RCHA'
   !
-  type, extends(BndType) :: RchType
-    integer(I4B), pointer :: inirch => NULL()
+  type, extends(BndExtType) :: RchType
+    real(DP), dimension(:), pointer, contiguous :: recharge => null() !< boundary recharge array
     integer(I4B), dimension(:), pointer, contiguous :: nodesontop => NULL() ! User provided cell numbers; nodelist is cells where recharge is applied)
-    logical, private :: fixed_cell = .false.
-    logical, private :: read_as_arrays = .false.
+    logical, pointer, private :: fixed_cell
+    logical, pointer, private :: read_as_arrays
+
   contains
+
     procedure :: rch_allocate_scalars
-    procedure :: bnd_options => rch_options
-    procedure :: read_dimensions => rch_read_dimensions
+    procedure :: allocate_arrays => rch_allocate_arrays
+    procedure :: source_options => rch_source_options
+    procedure :: source_dimensions => rch_source_dimensions
+    procedure :: log_rch_options
     procedure :: read_initial_attr => rch_read_initial_attr
     procedure :: bnd_rp => rch_rp
-    procedure :: set_nodesontop
     procedure :: bnd_cf => rch_cf
     procedure :: bnd_fc => rch_fc
     procedure :: bnd_da => rch_da
+    procedure :: set_nodesontop
     procedure :: define_listlabel => rch_define_listlabel
-    procedure, public :: bnd_rp_ts => rch_rp_ts
-    procedure, private :: rch_rp_array
-    procedure, private :: rch_rp_list
+    procedure :: bound_value => rch_bound_value
     procedure, private :: default_nodelist
     ! -- for observations
     procedure, public :: bnd_obs_supported => rch_obs_supported
     procedure, public :: bnd_df_obs => rch_df_obs
+
   end type RchType
 
 contains
 
-  subroutine rch_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
-! ******************************************************************************
-! rch_create -- Create a New Recharge Package
-! Subroutine: (1) create new-style package
-!             (2) point packobj to the new package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Create a New Recharge Package
+  !!
+  !! Create new RCH package and point packobj to the new package
+  !<
+  subroutine rch_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
+                        mempath)
     ! -- dummy
     class(BndType), pointer :: packobj
     integer(I4B), intent(in) :: id
@@ -67,16 +68,16 @@ subroutine rch_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     integer(I4B), intent(in) :: iout
     character(len=*), intent(in) :: namemodel
     character(len=*), intent(in) :: pakname
+    character(len=*), intent(in) :: mempath
     ! -- local
     type(rchtype), pointer :: rchobj
-! ------------------------------------------------------------------------------
     !
     ! -- allocate recharge object and scalar variables
     allocate (rchobj)
     packobj => rchobj
     !
     ! -- create name and memory path
-    call packobj%set_names(ibcnum, namemodel, pakname, ftype)
+    call packobj%set_names(ibcnum, namemodel, pakname, ftype, mempath)
     packobj%text = text
     !
     ! -- allocate scalars
@@ -84,550 +85,229 @@ subroutine rch_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     !
     ! -- initialize package
     call packobj%pack_initialize()
-
+    !
     packobj%inunit = inunit
     packobj%iout = iout
     packobj%id = id
     packobj%ibcnum = ibcnum
-    packobj%ncolbnd = 1
-    packobj%iscloc = 1 ! sfac applies to recharge rate
     packobj%ictMemPath = create_mem_path(namemodel, 'NPF')
-    ! indxconvertflux is Column index of bound that will be multiplied by
-    ! cell area to convert flux rates to flow rates
-    packobj%indxconvertflux = 1
-    packobj%AllowTimeArraySeries = .true.
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine rch_create
 
+  !> @brief Allocate scalar members
+  !<
   subroutine rch_allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars -- allocate scalar members
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(RchType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
-    ! -- call standard BndType allocate scalars
-    call this%BndType%allocate_scalars()
+    ! -- allocate base scalars
+    call this%BndExtType%allocate_scalars()
     !
-    ! -- allocate the object and assign values to object variables
-    call mem_allocate(this%inirch, 'INIRCH', this%memoryPath)
+    ! -- allocate internal members
+    allocate (this%fixed_cell)
+    allocate (this%read_as_arrays)
     !
     ! -- Set values
-    this%inirch = 0
     this%fixed_cell = .false.
+    this%read_as_arrays = .false.
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine rch_allocate_scalars
 
-  subroutine rch_options(this, option, found)
-! ******************************************************************************
-! rch_options -- set options specific to RchType
-!
-! rch_options overrides BndType%bnd_options
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use ConstantsModule, only: DZERO
-    use SimModule, only: store_error
+  !> @brief Allocate package arrays
+  !<
+  subroutine rch_allocate_arrays(this, nodelist, auxvar)
+    ! -- modules
+    use MemoryManagerModule, only: mem_setptr, mem_checkin
+    ! -- dummy
+    class(RchType) :: this
+    integer(I4B), dimension(:), pointer, contiguous, optional :: nodelist
+    real(DP), dimension(:, :), pointer, contiguous, optional :: auxvar
+    !
+    ! -- allocate base arrays
+    call this%BndExtType%allocate_arrays(nodelist, auxvar)
+    !
+    ! -- set recharge input context pointer
+    call mem_setptr(this%recharge, 'RECHARGE', this%input_mempath)
+    !
+    ! -- checkin recharge input context pointer
+    call mem_checkin(this%recharge, 'RECHARGE', this%memoryPath, &
+                     'RECHARGE', this%input_mempath)
+    !
+    ! -- Return
+    return
+  end subroutine rch_allocate_arrays
+
+  !> @brief Source options specific to RchType
+  !<
+  subroutine rch_source_options(this)
+    ! -- modules
+    use MemoryManagerExtModule, only: mem_set_value
     implicit none
     ! -- dummy
     class(RchType), intent(inout) :: this
-    character(len=*), intent(inout) :: option
-    logical, intent(inout) :: found
     ! -- local
-    character(len=MAXCHARLEN) :: ermsg
+    logical(LGP) :: found_fixed_cell = .false.
+    logical(LGP) :: found_readasarrays = .false.
+    !
+    ! -- source common bound options
+    call this%BndExtType%source_options()
+    !
+    ! -- update defaults with idm sourced values
+    call mem_set_value(this%fixed_cell, 'FIXED_CELL', this%input_mempath, &
+                       found_fixed_cell)
+    call mem_set_value(this%read_as_arrays, 'READASARRAYS', this%input_mempath, &
+                       found_readasarrays)
+    !
+    if (found_readasarrays) then
+      if (this%dis%supports_layers()) then
+        this%text = texta
+      else
+        errmsg = 'READASARRAYS option is not compatible with selected'// &
+                 ' discretization type.'
+        call store_error(errmsg)
+        call store_error_filename(this%input_fname)
+      end if
+    end if
+    !
+    ! -- log rch params
+    call this%log_rch_options(found_fixed_cell, found_readasarrays)
+    !
+    ! -- Return
+    return
+  end subroutine rch_source_options
+
+  !> @brief Log options specific to RchType
+  !<
+  subroutine log_rch_options(this, found_fixed_cell, found_readasarrays)
+    implicit none
+    ! -- dummy
+    class(RchType), intent(inout) :: this
+    logical(LGP), intent(in) :: found_fixed_cell
+    logical(LGP), intent(in) :: found_readasarrays
     ! -- formats
-    character(len=*), parameter :: fmtihact = &
-      &"(4x, 'RECHARGE WILL BE APPLIED TO HIGHEST ACTIVE CELL.')"
     character(len=*), parameter :: fmtfixedcell = &
       &"(4x, 'RECHARGE WILL BE APPLIED TO SPECIFIED CELL.')"
     character(len=*), parameter :: fmtreadasarrays = &
       &"(4x, 'RECHARGE INPUT WILL BE READ AS ARRAY(S).')"
-! ------------------------------------------------------------------------------
     !
-    ! -- Check for FIXED_CELL and READASARRAYS
-    select case (option)
-    case ('FIXED_CELL')
-      this%fixed_cell = .true.
+    ! -- log found options
+    write (this%iout, '(/1x,a)') 'PROCESSING '//trim(adjustl(this%text)) &
+      //' OPTIONS'
+    !
+    if (found_fixed_cell) then
       write (this%iout, fmtfixedcell)
-      found = .true.
-    case ('READASARRAYS')
-      if (this%dis%supports_layers()) then
-        this%read_as_arrays = .true.
-        this%text = texta
-      else
-        ermsg = 'READASARRAYS option is not compatible with selected'// &
-                ' discretization type.'
-        call store_error(ermsg)
-        call this%parser%StoreErrorUnit()
-      end if
-      !
-      ! -- Write option
+    end if
+    !
+    if (found_readasarrays) then
       write (this%iout, fmtreadasarrays)
-      !
-      found = .true.
-    case default
-      !
-      ! -- No options found
-      found = .false.
-    end select
+    end if
+    !
+    ! -- close logging block
+    write (this%iout, '(1x,a)') &
+      'END OF '//trim(adjustl(this%text))//' OPTIONS'
     !
-    ! -- return
+    ! -- Return
     return
-  end subroutine rch_options
+  end subroutine log_rch_options
 
-  subroutine rch_read_dimensions(this)
-! ******************************************************************************
-! bnd_read_dimensions -- Read the dimensions for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use ConstantsModule, only: LINELENGTH
-    use SimModule, only: store_error, store_error_unit
+  !> @brief Source the dimensions for this package
+  !!
+  !! Dimensions block is not required if:
+  !!   (1) discretization is DIS or DISV, and
+  !!   (2) READASARRAYS option has been specified.
+  !<
+  subroutine rch_source_dimensions(this)
     ! -- dummy
     class(RchType), intent(inout) :: this
-    ! -- local
-    character(len=LINELENGTH) :: keyword
-    integer(I4B) :: ierr
-    logical :: isfound, endOfBlock
-    ! -- format
-! ------------------------------------------------------------------------------
-    !
-    ! Dimensions block is not required if:
-    !   (1) discretization is DIS or DISV, and
-    !   (2) READASARRAYS option has been specified.
+    !
     if (this%read_as_arrays) then
       this%maxbound = this%dis%get_ncpl()
-    else
-      ! -- get dimensions block
-      call this%parser%GetBlock('DIMENSIONS', isfound, ierr, &
-                                supportOpenClose=.true.)
       !
-      ! -- parse dimensions block if detected
-      if (isfound) then
-        write (this%iout, '(/1x,a)') 'PROCESSING '//trim(adjustl(this%text))// &
-          ' DIMENSIONS'
-        do
-          call this%parser%GetNextLine(endOfBlock)
-          if (endOfBlock) exit
-          call this%parser%GetStringCaps(keyword)
-          select case (keyword)
-          case ('MAXBOUND')
-            this%maxbound = this%parser%GetInteger()
-            write (this%iout, '(4x,a,i7)') 'MAXBOUND = ', this%maxbound
-          case default
-            write (errmsg, '(a,a)') &
-              'Unknown '//trim(this%text)//' DIMENSION: ', trim(keyword)
-            call store_error(errmsg)
-            call this%parser%StoreErrorUnit()
-          end select
-        end do
-        !
-        write (this%iout, '(1x,a)') &
-          'END OF '//trim(adjustl(this%text))//' DIMENSIONS'
-      else
-        call store_error('Required DIMENSIONS block not found.')
-        call this%parser%StoreErrorUnit()
+      ! -- verify dimensions were set
+      if (this%maxbound <= 0) then
+        write (errmsg, '(a)') &
+          'MAXBOUND must be an integer greater than zero.'
+        call store_error(errmsg)
+        call store_error_filename(this%input_fname)
       end if
-    end if
-    !
-    ! -- verify dimensions were set
-    if (this%maxbound <= 0) then
-      write (errmsg, '(a)') &
-        'MAXBOUND must be an integer greater than zero.'
-      call store_error(errmsg)
-      call this%parser%StoreErrorUnit()
+      !
+    else
+      !
+      ! -- source maxbound
+      call this%BndExtType%source_dimensions()
     end if
     !
     ! -- Call define_listlabel to construct the list label that is written
     !    when PRINT_INPUT option is used.
     call this%define_listlabel()
     !
-    ! -- return
+    ! -- Return
     return
-  end subroutine rch_read_dimensions
+  end subroutine rch_source_dimensions
 
+  !> @brief Part of allocate and read
+  !<
   subroutine rch_read_initial_attr(this)
-! ******************************************************************************
-! rch_read_initial_attr -- Part of allocate and read
-! If READASARRAYS has been specified, assign default IRCH = 1
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(RchType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
     if (this%read_as_arrays) then
       call this%default_nodelist()
     end if
     !
+    ! -- Return
     return
   end subroutine rch_read_initial_attr
 
+  !> @brief Read and Prepare
+  !!
+  !! Read itmp and read new boundaries if itmp > 0
+  !<
   subroutine rch_rp(this)
-! ******************************************************************************
-! rch_rp -- Read and Prepare
-! Subroutine: (1) read itmp
-!             (2) read new boundaries if itmp>0
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use ConstantsModule, only: LINELENGTH
-    use TdisModule, only: kper, nper
-    use SimModule, only: store_error
+    ! -- modules
+    use TdisModule, only: kper
     implicit none
     ! -- dummy
     class(RchType), intent(inout) :: this
-    ! -- local
-    integer(I4B) :: ierr
-    integer(I4B) :: node, n
-    integer(I4B) :: inirch, inrech
-    logical :: isfound
-    logical :: supportopenclose
-    character(len=LINELENGTH) :: line
-    ! -- formats
-    character(len=*), parameter :: fmtblkerr = &
-      &"('Looking for BEGIN PERIOD iper.  Found ', a, ' instead.')"
-    character(len=*), parameter :: fmtlsp = &
-      &"(1X,/1X,'REUSING ',A,'S FROM LAST STRESS PERIOD')"
-    character(len=*), parameter :: fmtnbd = &
-      "(1X,/1X,'THE NUMBER OF ACTIVE ',A,'S (',I6, &
-      &') IS GREATER THAN MAXIMUM(',I6,')')"
-    character(len=*), parameter :: fmtdimlayered = &
-      "('When READASARRAYS is specified for the selected discretization &
-      &package, DIMENSIONS block must be omitted.')"
-! ------------------------------------------------------------------------------
-    !
-    if (this%inunit == 0) return
-    !
-    ! -- Set ionper to the stress period number for which a new block of data
-    !    will be read.
-    if (this%ionper < kper) then
-      !
-      ! -- get period block
-      supportopenclose = .not. this%read_as_arrays
-      ! When reading a list, OPEN/CLOSE is handled by list reader,
-      ! so supportOpenClose needs to be false in call the GetBlock.
-      ! When reading as arrays, set supportOpenClose as desired.
-      call this%parser%GetBlock('PERIOD', isfound, ierr, &
-                                blockRequired=.false.)
-      if (isfound) then
-        !
-        ! -- read ionper and check for increasing period numbers
-        call this%read_check_ionper()
-      else
-        !
-        ! -- PERIOD block not found
-        if (ierr < 0) then
-          ! -- End of file found; data applies for remainder of simulation.
-          this%ionper = nper + 1
-        else
-          ! -- Found invalid block
-          call this%parser%GetCurrentLine(line)
-          write (errmsg, fmtblkerr) adjustl(trim(line))
-          call store_error(errmsg)
-          if (this%read_as_arrays) then
-            write (errmsg, fmtdimlayered)
-            call store_error(errmsg)
-          end if
-          call this%parser%StoreErrorUnit()
-        end if
-      end if
-    end if
     !
-    ! -- Read data if ionper == kper
-    inrech = 0
-    inirch = 0
-    if (this%ionper == kper) then
-      !
-      ! -- Remove all time-series links associated with this package
-      call this%TsManager%Reset(this%packName)
-      call this%TasManager%Reset(this%packName)
+    if (this%iper /= kper) return
+    !
+    if (this%read_as_arrays) then
       !
-      if (.not. this%read_as_arrays) then
-        ! -- Read RECHARGE and other input as a list
-        call this%rch_rp_list(inrech)
-        call this%bnd_rp_ts()
-      else
-        ! -- Read RECHARGE, IRCH, and AUX variables as arrays
-        call this%rch_rp_array(line, inrech)
-      end if
+      ! -- update nodelist based on IRCH input
+      call nodelist_update(this%nodelist, this%nbound, this%maxbound, &
+                           this%dis, this%input_mempath)
       !
     else
-      write (this%iout, fmtlsp) trim(this%filtyp)
-    end if
-    !
-    ! -- If recharge was read, then multiply by cell area.  If inrech = 2, then
-    !    recharge is begin managed as a time series, and the time series object
-    !    will multiply the recharge rate by the cell area.
-    if (inrech == 1) then
-      do n = 1, this%nbound
-        node = this%nodelist(n)
-        if (node > 0) then
-          this%bound(1, n) = this%bound(1, n) * this%dis%get_area(node)
-        end if
-      end do
-    end if
-    !
-    ! -- return
-    return
-  end subroutine rch_rp
-
-  subroutine rch_rp_array(this, line, inrech)
-! ******************************************************************************
-! rch_rp_array -- Read and Prepare Recharge as arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use ConstantsModule, only: LENTIMESERIESNAME, LINELENGTH
-    use SimModule, only: store_error
-    use ArrayHandlersModule, only: ifind
-    implicit none
-    ! -- dummy
-    class(RchType), intent(inout) :: this
-    character(len=LINELENGTH), intent(inout) :: line
-    integer(I4B), intent(inout) :: inrech
-    ! -- local
-    integer(I4B) :: n
-    integer(I4B) :: ipos
-    integer(I4B) :: jcol, jauxcol, lpos, ivarsread
-    character(len=LENTIMESERIESNAME) :: tasName
-    character(len=24), dimension(2) :: aname
-    character(len=LINELENGTH) :: keyword, atemp
-    logical :: found, endOfBlock
-    logical :: convertFlux
-    !
-    ! -- these time array series pointers need to be non-contiguous
-    !    beacuse a slice of bound is passed
-    real(DP), dimension(:), pointer :: bndArrayPtr => null()
-    real(DP), dimension(:), pointer :: auxArrayPtr => null()
-    real(DP), dimension(:), pointer :: auxMultArray => null()
-    type(TimeArraySeriesLinkType), pointer :: tasLink => null()
-    ! -- formats
-    character(len=*), parameter :: fmtrchauxmult = &
-      "(4x, 'THE RECHARGE ARRAY IS BEING MULTIPLED BY THE AUXILIARY ARRAY WITH &
-        &THE NAME: ', A)"
-    ! -- data
-    data aname(1)/'     LAYER OR NODE INDEX'/
-    data aname(2)/'                RECHARGE'/
-    !
-! ------------------------------------------------------------------------------
-    !
-    ! -- Initialize
-    jauxcol = 0
-    ivarsread = 0
-    !
-    ! -- Read RECHARGE, IRCH, and AUX variables as arrays
-    do
-      call this%parser%GetNextLine(endOfBlock)
-      if (endOfBlock) exit
-      call this%parser%GetStringCaps(keyword)
-      !
-      ! -- Parse the keywords
-      select case (keyword)
-      case ('RECHARGE')
-        !
-        ! -- Look for keyword TIMEARRAYSERIES and time-array series
-        !    name on line, following RECHARGE
-        call this%parser%GetStringCaps(keyword)
-        if (keyword == 'TIMEARRAYSERIES') then
-          ! -- Get time-array series name
-          call this%parser%GetStringCaps(tasName)
-          jcol = 1 ! for recharge rate
-          bndArrayPtr => this%bound(jcol, :)
-          ! Make a time-array-series link and add it to the list of links
-          ! contained in the TimeArraySeriesManagerType object.
-          convertflux = .true.
-          call this%TasManager%MakeTasLink(this%packName, bndArrayPtr, &
-                                           this%iprpak, tasName, 'RECHARGE', &
-                                           convertFlux, this%nodelist, &
-                                           this%parser%iuactive)
-          lpos = this%TasManager%CountLinks()
-          tasLink => this%TasManager%GetLink(lpos)
-          inrech = 2
-        else
-          !
-          ! -- Read the recharge array, then indicate
-          !    that recharge was read by setting inrech
-          call this%dis%read_layer_array(this%nodelist, this%bound, &
-                                         this%ncolbnd, this%maxbound, 1, &
-                                         aname(2), this%parser%iuactive, &
-                                         this%iout)
-          inrech = 1
-        end if
-        !
-      case ('IRCH')
-        !
-        ! -- Check to see if other variables have already been read.  If so,
-        !    then terminate with an error that IRCH must be read first.
-        if (ivarsread > 0) then
-          call store_error('IRCH IS NOT FIRST VARIABLE IN &
-            &PERIOD BLOCK OR IT IS SPECIFIED MORE THAN ONCE.')
-          call this%parser%StoreErrorUnit()
-        end if
-        !
-        ! -- Read the IRCH array
-        call this%dis%nlarray_to_nodelist(this%nodelist, this%maxbound, &
-                                          this%nbound, aname(1), &
-                                          this%parser%iuactive, this%iout)
-        !
-        ! -- set flag to indicate that irch array has been read
-        this%inirch = 1
-        !
-        ! -- if fixed_cell option not set, then need to store nodelist
-        !    in the nodesontop array
-        if (.not. this%fixed_cell) call this%set_nodesontop()
-        !
-      case default
-        !
-        ! -- Check for auxname, and if found, then read into auxvar array
-        found = .false.
-        ipos = ifind(this%auxname, keyword)
-        if (ipos > 0) then
-          found = .true.
-          atemp = keyword
-          !
-          ! -- Look for keyword TIMEARRAYSERIES and time-array series
-          !    name on line, following auxname
-          call this%parser%GetStringCaps(keyword)
-          if (keyword == 'TIMEARRAYSERIES') then
-            ! -- Get time-array series name
-            call this%parser%GetStringCaps(tasName)
-            jauxcol = jauxcol + 1
-            auxArrayPtr => this%auxvar(jauxcol, :)
-            ! Make a time-array-series link and add it to the list of links
-            ! contained in the TimeArraySeriesManagerType object.
-            convertflux = .false.
-            call this%TasManager%MakeTasLink(this%packName, auxArrayPtr, &
-                                             this%iprpak, tasName, &
-                                             this%auxname(ipos), convertFlux, &
-                                             this%nodelist, &
-                                             this%parser%iuactive)
-          else
-            !
-            ! -- Read the aux variable array
-            call this%dis%read_layer_array(this%nodelist, this%auxvar, &
-                                           this%naux, this%maxbound, ipos, &
-                                           atemp, this%parser%iuactive, this%iout)
-          end if
-        end if
-        !
-        ! -- Nothing found
-        if (.not. found) then
-          call this%parser%GetCurrentLine(line)
-          errmsg = 'LOOKING FOR VALID VARIABLE NAME.  FOUND: '//trim(line)
-          call store_error(errmsg)
-          call this%parser%StoreErrorUnit()
-        end if
-        !
-        ! -- If this aux variable has been designated as a multiplier array
-        !    by presence of AUXMULTNAME, set local pointer appropriately.
-        if (this%iauxmultcol > 0 .and. this%iauxmultcol == ipos) then
-          auxMultArray => this%auxvar(this%iauxmultcol, :)
-        end if
-      end select
       !
-      ! -- Increment the number of variables read
-      ivarsread = ivarsread + 1
+      call this%BndExtType%bnd_rp()
       !
-    end do
-    !
-    ! -- If the multiplier-array pointer has been assigned and
-    !    stress is controlled by a time-array series, assign
-    !    multiplier-array pointer in time-array series link.
-    if (associated(auxMultArray)) then
-      if (associated(tasLink)) then
-        tasLink%RMultArray => auxMultArray
-      end if
     end if
     !
-    ! -- If recharge was read and auxmultcol was specified, then multiply
-    !    the recharge rate by the multplier column
-    if (inrech == 1 .and. this%iauxmultcol > 0) then
-      write (this%iout, fmtrchauxmult) this%auxname(this%iauxmultcol)
-      do n = 1, this%nbound
-        this%bound(this%iscloc, n) = this%bound(this%iscloc, n) * &
-                                     this%auxvar(this%iauxmultcol, n)
-      end do
-    end if
-    !
-    return
-  end subroutine rch_rp_array
-
-  subroutine rch_rp_list(this, inrech)
-! ******************************************************************************
-! rch_rp_list -- Read and Prepare Recharge as a list
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    implicit none
-    ! -- dummy
-    class(RchType), intent(inout) :: this
-    integer(I4B), intent(inout) :: inrech
-    ! -- local
-    integer(I4B) :: maxboundorig, nlist
-    !
-! ------------------------------------------------------------------------------
-    !
-    ! -- initialize
-    nlist = -1
-    maxboundorig = this%maxbound
-    !
-    ! -- read the list of recharge values; scale the recharge by auxmultcol
-    !    if it is specified.
-    call this%dis%read_list(this%parser%iuactive, this%iout, this%iprpak, &
-                            nlist, this%inamedbound, this%iauxmultcol, &
-                            this%nodelist, this%bound, this%auxvar, &
-                            this%auxname, this%boundname, this%listlabel, &
-                            this%packName, this%tsManager, this%iscloc, &
-                            this%indxconvertflux)
-    this%nbound = nlist
-    if (this%maxbound > maxboundorig) then
-      ! -- The arrays that belong to BndType have been extended.
-      ! Now, RCH array nodesontop needs to be recreated.
-      if (associated(this%nodesontop)) then
-        deallocate (this%nodesontop)
-      end if
-    end if
+    ! -- copy nodelist to nodesontop if not fixed cell
     if (.not. this%fixed_cell) call this%set_nodesontop()
-    inrech = 1
     !
-    ! -- terminate the period block
-    call this%parser%terminateblock()
+    ! -- Write the list to iout if requested
+    if (this%iprpak /= 0) then
+      call this%write_list()
+    end if
     !
+    ! -- Return
     return
-  end subroutine rch_rp_list
+  end subroutine rch_rp
 
+  !> @brief Store nodelist in nodesontop
+  !<
   subroutine set_nodesontop(this)
-! ******************************************************************************
-! set_nodesontop -- store nodelist in nodesontop
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     implicit none
     ! -- dummy
     class(RchType), intent(inout) :: this
     ! -- local
     integer(I4B) :: n
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- allocate if necessary
     if (.not. associated(this%nodesontop)) then
@@ -639,25 +319,19 @@ subroutine set_nodesontop(this)
       this%nodesontop(n) = this%nodelist(n)
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine set_nodesontop
 
-  subroutine rch_cf(this, reset_mover)
-! ******************************************************************************
-! rch_cf -- Formulate the HCOF and RHS terms
-! Subroutine: (1) skip if no recharge
-!             (2) calculate hcof and rhs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Formulate the HCOF and RHS terms
+  !!
+  !! Skip if no recharge. Otherwise, calculate hcof and rhs
+  !<
+  subroutine rch_cf(this)
     ! -- dummy
     class(rchtype) :: this
-    logical, intent(in), optional :: reset_mover
     ! -- local
     integer(I4B) :: i, node
-! ------------------------------------------------------------------------------
     !
     ! -- Return if no recharge
     if (this%nbound == 0) return
@@ -688,7 +362,12 @@ subroutine rch_cf(this, reset_mover)
       !
       ! -- Set rhs and hcof
       this%hcof(i) = DZERO
-      this%rhs(i) = -this%bound(1, i)
+      if (this%iauxmultcol > 0) then
+        this%rhs(i) = -this%recharge(i) * this%dis%get_area(node) * &
+                      this%auxvar(this%iauxmultcol, i)
+      else
+        this%rhs(i) = -this%recharge(i) * this%dis%get_area(node)
+      end if
       if (this%ibound(node) <= 0) then
         this%rhs(i) = DZERO
         cycle
@@ -699,17 +378,13 @@ subroutine rch_cf(this, reset_mover)
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine rch_cf
 
+  !> @brief Copy rhs and hcof into solution rhs and amat
+  !<
   subroutine rch_fc(this, rhs, ia, idxglo, matrix_sln)
-! **************************************************************************
-! rch_fc -- Copy rhs and hcof into solution rhs and amat
-! **************************************************************************
-!
-!    SPECIFICATIONS:
-! --------------------------------------------------------------------------
     ! -- dummy
     class(RchType) :: this
     real(DP), dimension(:), intent(inout) :: rhs
@@ -718,7 +393,6 @@ subroutine rch_fc(this, rhs, ia, idxglo, matrix_sln)
     class(MatrixBaseType), pointer :: matrix_sln
     ! -- local
     integer(I4B) :: i, n, ipos
-! --------------------------------------------------------------------------
     !
     ! -- Copy package rhs and hcof into solution rhs and amat
     do i = 1, this%nbound
@@ -735,46 +409,39 @@ subroutine rch_fc(this, rhs, ia, idxglo, matrix_sln)
       call matrix_sln%add_value_pos(idxglo(ipos), this%hcof(i))
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine rch_fc
 
+  !> @brief Deallocate memory
+  !<
   subroutine rch_da(this)
-! ******************************************************************************
-! rch_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(RchType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Deallocate parent package
-    call this%BndType%bnd_da()
+    call this%BndExtType%bnd_da()
     !
     ! -- scalars
-    call mem_deallocate(this%inirch)
+    deallocate (this%fixed_cell)
+    deallocate (this%read_as_arrays)
     !
     ! -- arrays
     if (associated(this%nodesontop)) deallocate (this%nodesontop)
+    call mem_deallocate(this%recharge, 'RECHARGE', this%memoryPath)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine rch_da
 
+  !> @brief Define the list heading that is written to iout when PRINT_INPUT
+  !! option is used.
+  !<
   subroutine rch_define_listlabel(this)
-! ******************************************************************************
-! define_listlabel -- Define the list heading that is written to iout when
-!   PRINT_INPUT option is used.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     class(RchType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- create the header list label
     this%listlabel = trim(this%filtyp)//' NO.'
@@ -795,27 +462,19 @@ subroutine rch_define_listlabel(this)
       write (this%listlabel, '(a, a16)') trim(this%listlabel), 'BOUNDARY NAME'
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine rch_define_listlabel
 
+  !> @brief Assign default nodelist when READASARRAYS is specified.
+  !!
+  !! Equivalent to reading IRCH as CONSTANT 1
+  !<
   subroutine default_nodelist(this)
-! ******************************************************************************
-! default_nodelist -- Assign default nodelist when READASARRAYS is specified.
-!                     Equivalent to reading IRCH as CONSTANT 1
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use InputOutputModule, only: get_node
-    use SimModule, only: store_error
-    use ConstantsModule, only: LINELENGTH
     ! -- dummy
     class(RchType) :: this
     ! -- local
     integer(I4B) :: il, ir, ic, ncol, nrow, nlay, nodeu, noder, ipos
-! ------------------------------------------------------------------------------
     !
     ! -- set variables
     if (this%dis%ndim == 3) then
@@ -840,84 +499,129 @@ subroutine default_nodelist(this)
       end do
     end do
     !
-    ! Set flag that indicates IRCH has been assigned, and assign nbound.
-    this%inirch = 1
+    ! -- Assign nbound
     this%nbound = ipos - 1
     !
     ! -- if fixed_cell option not set, then need to store nodelist
     !    in the nodesontop array
     if (.not. this%fixed_cell) call this%set_nodesontop()
     !
-    ! -- return
+    ! -- Return
+    return
   end subroutine default_nodelist
 
   ! -- Procedures related to observations
+
+  !> @brief
+  !!
+  !! Overrides BndType%bnd_obs_supported()
+  !<
   logical function rch_obs_supported(this)
-    ! ******************************************************************************
-    ! rch_obs_supported
-    !   -- Return true because RCH package supports observations.
-    !   -- Overrides BndType%bnd_obs_supported()
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
     implicit none
+    ! -- dummy
     class(RchType) :: this
-    ! ------------------------------------------------------------------------------
+    !
     rch_obs_supported = .true.
     !
-    ! -- return
+    ! -- Return
     return
   end function rch_obs_supported
 
+  !> @brief Implements bnd_df_obs
+  !!
+  !! Store observation type supported by RCH package. Overrides
+  !! BndType%bnd_df_obs
+  !<
   subroutine rch_df_obs(this)
-    ! ******************************************************************************
-    ! rch_df_obs (implements bnd_df_obs)
-    !   -- Store observation type supported by RCH package.
-    !   -- Overrides BndType%bnd_df_obs
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
     implicit none
     ! -- dummy
     class(RchType) :: this
     ! -- local
     integer(I4B) :: indx
-    ! ------------------------------------------------------------------------------
+    !
     call this%obs%StoreObsType('rch', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => DefaultObsIdProcessor
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine rch_df_obs
 
-  !
-  ! -- Procedure related to time series
-  subroutine rch_rp_ts(this)
-    ! -- Assign tsLink%Text appropriately for
-    !    all time series in use by package.
-    !    In RCH package only the RECHARGE variable
-    !    can be controlled by time series.
+  !> @brief Return requested boundary value
+  !<
+  function rch_bound_value(this, col, row) result(bndval)
+    ! -- modules
+    use ConstantsModule, only: DZERO
     ! -- dummy
-    class(RchType), intent(inout) :: this
-    ! -- local
-    integer(I4B) :: i, nlinks
-    type(TimeSeriesLinkType), pointer :: tslink => null()
-    !
-    nlinks = this%TsManager%boundtslinks%Count()
-    do i = 1, nlinks
-      tslink => GetTimeSeriesLinkFromList(this%TsManager%boundtslinks, i)
-      if (associated(tslink)) then
-        select case (tslink%JCol)
-        case (1)
-          tslink%Text = 'RECHARGE'
-        end select
+    class(RchType), intent(inout) :: this !< BndExtType object
+    integer(I4B), intent(in) :: col
+    integer(I4B), intent(in) :: row
+    ! -- result
+    real(DP) :: bndval
+    !
+    select case (col)
+    case (1)
+      if (this%iauxmultcol > 0) then
+        bndval = this%recharge(row) * this%auxvar(this%iauxmultcol, row)
+      else
+        bndval = this%recharge(row)
       end if
-    end do
+    case default
+      errmsg = 'Programming error. RCH bound value requested column '&
+               &'outside range of ncolbnd (1).'
+      call store_error(errmsg)
+      call store_error_filename(this%input_fname)
+    end select
+    !
+    ! -- Return
+    return
+  end function rch_bound_value
+
+  !> @brief Update the nodelist based on IRCH input
+  !!
+  !! This is a module scoped routine to check for IRCH
+  !! input. If array input was provided, INIRCH and IRCH
+  !! will be allocated in the input context.  If the read
+  !! state variable INIRCH is set to 1 during this period
+  !! update, IRCH input was read and is used here to update
+  !! the nodelist.
+  !!
+  !<
+  subroutine nodelist_update(nodelist, nbound, maxbound, &
+                             dis, input_mempath)
+    ! -- modules
+    use MemoryManagerModule, only: mem_setptr
+    use BaseDisModule, only: DisBaseType
+    ! -- dummy
+    integer(I4B), dimension(:), contiguous, &
+      pointer, intent(inout) :: nodelist
+    class(DisBaseType), pointer, intent(in) :: dis
+    character(len=*), intent(in) :: input_mempath
+    integer(I4B), intent(inout) :: nbound
+    integer(I4B), intent(in) :: maxbound
+    character(len=24) :: aname = '     LAYER OR NODE INDEX'
+    ! -- local
+    integer(I4B), dimension(:), contiguous, &
+      pointer :: irch => null()
+    integer(I4B), pointer :: inirch => NULL()
+    !
+    ! -- set pointer to input context INIRCH
+    call mem_setptr(inirch, 'INIRCH', input_mempath)
+    !
+    ! -- check INIRCH read state
+    if (inirch == 1) then
+      ! -- irch was read this period
+      !
+      ! -- set pointer to input context IRCH
+      call mem_setptr(irch, 'IRCH', input_mempath)
+      !
+      ! -- update nodelist
+      call dis%nlarray_to_nodelist(irch, nodelist, &
+                                   maxbound, nbound, aname)
+    end if
     !
+    ! -- Return
     return
-  end subroutine rch_rp_ts
+  end subroutine nodelist_update
 
 end module RchModule
 
diff --git a/src/Model/GroundWaterFlow/gwf3rch8idm.f90 b/src/Model/GroundWaterFlow/gwf3rch8idm.f90
new file mode 100644
index 00000000000..a39fff2acda
--- /dev/null
+++ b/src/Model/GroundWaterFlow/gwf3rch8idm.f90
@@ -0,0 +1,430 @@
+! ** Do Not Modify! MODFLOW 6 system generated file. **
+module GwfRchInputModule
+  use ConstantsModule, only: LENVARNAME
+  use InputDefinitionModule, only: InputParamDefinitionType, &
+                                   InputBlockDefinitionType
+  private
+  public gwf_rch_param_definitions
+  public gwf_rch_aggregate_definitions
+  public gwf_rch_block_definitions
+  public GwfRchParamFoundType
+  public gwf_rch_multi_package
+
+  type GwfRchParamFoundType
+    logical :: fixed_cell = .false.
+    logical :: auxiliary = .false.
+    logical :: auxmultname = .false.
+    logical :: boundnames = .false.
+    logical :: iprpak = .false.
+    logical :: iprflow = .false.
+    logical :: ipakcb = .false.
+    logical :: ts_filerecord = .false.
+    logical :: ts6 = .false.
+    logical :: filein = .false.
+    logical :: ts6_filename = .false.
+    logical :: obs_filerecord = .false.
+    logical :: obs6 = .false.
+    logical :: obs6_filename = .false.
+    logical :: maxbound = .false.
+    logical :: cellid = .false.
+    logical :: recharge = .false.
+    logical :: auxvar = .false.
+    logical :: boundname = .false.
+  end type GwfRchParamFoundType
+
+  logical :: gwf_rch_multi_package = .true.
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_fixed_cell = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'OPTIONS', & ! block
+    'FIXED_CELL', & ! tag name
+    'FIXED_CELL', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_auxiliary = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXILIARY', & ! tag name
+    'AUXILIARY', & ! fortran variable
+    'STRING', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_auxmultname = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXMULTNAME', & ! tag name
+    'AUXMULTNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_boundnames = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'OPTIONS', & ! block
+    'BOUNDNAMES', & ! tag name
+    'BOUNDNAMES', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_iprpak = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_INPUT', & ! tag name
+    'IPRPAK', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_iprflow = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_FLOWS', & ! tag name
+    'IPRFLOW', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_ipakcb = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'OPTIONS', & ! block
+    'SAVE_FLOWS', & ! tag name
+    'IPAKCB', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_ts_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS_FILERECORD', & ! tag name
+    'TS_FILERECORD', & ! fortran variable
+    'RECORD TS6 FILEIN TS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_ts6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS6', & ! tag name
+    'TS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_filein = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'OPTIONS', & ! block
+    'FILEIN', & ! tag name
+    'FILEIN', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_ts6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS6_FILENAME', & ! tag name
+    'TS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_obs_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS_FILERECORD', & ! tag name
+    'OBS_FILERECORD', & ! fortran variable
+    'RECORD OBS6 FILEIN OBS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_obs6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6', & ! tag name
+    'OBS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_obs6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6_FILENAME', & ! tag name
+    'OBS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_maxbound = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'DIMENSIONS', & ! block
+    'MAXBOUND', & ! tag name
+    'MAXBOUND', & ! fortran variable
+    'INTEGER', & ! type
+    '', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_cellid = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'PERIOD', & ! block
+    'CELLID', & ! tag name
+    'CELLID', & ! fortran variable
+    'INTEGER1D', & ! type
+    'NCELLDIM', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_recharge = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'PERIOD', & ! block
+    'RECHARGE', & ! tag name
+    'RECHARGE', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_auxvar = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'PERIOD', & ! block
+    'AUX', & ! tag name
+    'AUXVAR', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_boundname = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'PERIOD', & ! block
+    'BOUNDNAME', & ! tag name
+    'BOUNDNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_rch_param_definitions(*) = &
+    [ &
+    gwfrch_fixed_cell, &
+    gwfrch_auxiliary, &
+    gwfrch_auxmultname, &
+    gwfrch_boundnames, &
+    gwfrch_iprpak, &
+    gwfrch_iprflow, &
+    gwfrch_ipakcb, &
+    gwfrch_ts_filerecord, &
+    gwfrch_ts6, &
+    gwfrch_filein, &
+    gwfrch_ts6_filename, &
+    gwfrch_obs_filerecord, &
+    gwfrch_obs6, &
+    gwfrch_obs6_filename, &
+    gwfrch_maxbound, &
+    gwfrch_cellid, &
+    gwfrch_recharge, &
+    gwfrch_auxvar, &
+    gwfrch_boundname &
+    ]
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrch_spd = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCH', & ! subcomponent
+    'PERIOD', & ! block
+    'STRESS_PERIOD_DATA', & ! tag name
+    'SPD', & ! fortran variable
+    'RECARRAY CELLID RECHARGE AUX BOUNDNAME', & ! type
+    'MAXBOUND', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_rch_aggregate_definitions(*) = &
+    [ &
+    gwfrch_spd &
+    ]
+
+  type(InputBlockDefinitionType), parameter :: &
+    gwf_rch_block_definitions(*) = &
+    [ &
+    InputBlockDefinitionType( &
+    'OPTIONS', & ! blockname
+    .false., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'DIMENSIONS', & ! blockname
+    .true., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'PERIOD', & ! blockname
+    .true., & ! required
+    .true., & ! aggregate
+    .true. & ! block_variable
+    ) &
+    ]
+
+end module GwfRchInputModule
diff --git a/src/Model/GroundWaterFlow/gwf3rcha8idm.f90 b/src/Model/GroundWaterFlow/gwf3rcha8idm.f90
new file mode 100644
index 00000000000..d692d12ee29
--- /dev/null
+++ b/src/Model/GroundWaterFlow/gwf3rcha8idm.f90
@@ -0,0 +1,383 @@
+! ** Do Not Modify! MODFLOW 6 system generated file. **
+module GwfRchaInputModule
+  use ConstantsModule, only: LENVARNAME
+  use InputDefinitionModule, only: InputParamDefinitionType, &
+                                   InputBlockDefinitionType
+  private
+  public gwf_rcha_param_definitions
+  public gwf_rcha_aggregate_definitions
+  public gwf_rcha_block_definitions
+  public GwfRchaParamFoundType
+  public gwf_rcha_multi_package
+
+  type GwfRchaParamFoundType
+    logical :: readasarrays = .false.
+    logical :: fixed_cell = .false.
+    logical :: auxiliary = .false.
+    logical :: auxmultname = .false.
+    logical :: iprpak = .false.
+    logical :: iprflow = .false.
+    logical :: ipakcb = .false.
+    logical :: tas_filerecord = .false.
+    logical :: tas6 = .false.
+    logical :: filein = .false.
+    logical :: tas6_filename = .false.
+    logical :: obs_filerecord = .false.
+    logical :: obs6 = .false.
+    logical :: obs6_filename = .false.
+    logical :: irch = .false.
+    logical :: recharge = .false.
+    logical :: auxvar = .false.
+  end type GwfRchaParamFoundType
+
+  logical :: gwf_rcha_multi_package = .true.
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrcha_readasarrays = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCHA', & ! subcomponent
+    'OPTIONS', & ! block
+    'READASARRAYS', & ! tag name
+    'READASARRAYS', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrcha_fixed_cell = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCHA', & ! subcomponent
+    'OPTIONS', & ! block
+    'FIXED_CELL', & ! tag name
+    'FIXED_CELL', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrcha_auxiliary = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCHA', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXILIARY', & ! tag name
+    'AUXILIARY', & ! fortran variable
+    'STRING', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrcha_auxmultname = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCHA', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXMULTNAME', & ! tag name
+    'AUXMULTNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrcha_iprpak = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCHA', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_INPUT', & ! tag name
+    'IPRPAK', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrcha_iprflow = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCHA', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_FLOWS', & ! tag name
+    'IPRFLOW', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrcha_ipakcb = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCHA', & ! subcomponent
+    'OPTIONS', & ! block
+    'SAVE_FLOWS', & ! tag name
+    'IPAKCB', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrcha_tas_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCHA', & ! subcomponent
+    'OPTIONS', & ! block
+    'TAS_FILERECORD', & ! tag name
+    'TAS_FILERECORD', & ! fortran variable
+    'RECORD TAS6 FILEIN TAS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrcha_tas6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCHA', & ! subcomponent
+    'OPTIONS', & ! block
+    'TAS6', & ! tag name
+    'TAS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrcha_filein = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCHA', & ! subcomponent
+    'OPTIONS', & ! block
+    'FILEIN', & ! tag name
+    'FILEIN', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrcha_tas6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCHA', & ! subcomponent
+    'OPTIONS', & ! block
+    'TAS6_FILENAME', & ! tag name
+    'TAS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrcha_obs_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCHA', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS_FILERECORD', & ! tag name
+    'OBS_FILERECORD', & ! fortran variable
+    'RECORD OBS6 FILEIN OBS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrcha_obs6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCHA', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6', & ! tag name
+    'OBS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrcha_obs6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCHA', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6_FILENAME', & ! tag name
+    'OBS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrcha_irch = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCHA', & ! subcomponent
+    'PERIOD', & ! block
+    'IRCH', & ! tag name
+    'IRCH', & ! fortran variable
+    'INTEGER1D', & ! type
+    'NCPL', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrcha_recharge = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCHA', & ! subcomponent
+    'PERIOD', & ! block
+    'RECHARGE', & ! tag name
+    'RECHARGE', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NCPL', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfrcha_auxvar = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RCHA', & ! subcomponent
+    'PERIOD', & ! block
+    'AUX', & ! tag name
+    'AUXVAR', & ! fortran variable
+    'DOUBLE2D', & ! type
+    'NAUX NCPL', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_rcha_param_definitions(*) = &
+    [ &
+    gwfrcha_readasarrays, &
+    gwfrcha_fixed_cell, &
+    gwfrcha_auxiliary, &
+    gwfrcha_auxmultname, &
+    gwfrcha_iprpak, &
+    gwfrcha_iprflow, &
+    gwfrcha_ipakcb, &
+    gwfrcha_tas_filerecord, &
+    gwfrcha_tas6, &
+    gwfrcha_filein, &
+    gwfrcha_tas6_filename, &
+    gwfrcha_obs_filerecord, &
+    gwfrcha_obs6, &
+    gwfrcha_obs6_filename, &
+    gwfrcha_irch, &
+    gwfrcha_recharge, &
+    gwfrcha_auxvar &
+    ]
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_rcha_aggregate_definitions(*) = &
+    [ &
+    InputParamDefinitionType &
+    ( &
+    '', & ! component
+    '', & ! subcomponent
+    '', & ! block
+    '', & ! tag name
+    '', & ! fortran variable
+    '', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    ) &
+    ]
+
+  type(InputBlockDefinitionType), parameter :: &
+    gwf_rcha_block_definitions(*) = &
+    [ &
+    InputBlockDefinitionType( &
+    'OPTIONS', & ! blockname
+    .true., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'PERIOD', & ! blockname
+    .true., & ! required
+    .false., & ! aggregate
+    .true. & ! block_variable
+    ) &
+    ]
+
+end module GwfRchaInputModule
diff --git a/src/Model/GroundWaterFlow/gwf3riv8.f90 b/src/Model/GroundWaterFlow/gwf3riv8.f90
index 8feffb43f43..5822f72944f 100644
--- a/src/Model/GroundWaterFlow/gwf3riv8.f90
+++ b/src/Model/GroundWaterFlow/gwf3riv8.f90
@@ -1,11 +1,12 @@
 module rivmodule
   use KindModule, only: DP, I4B
   use ConstantsModule, only: DZERO, LENFTYPE, LENPACKAGENAME
+  use SimVariablesModule, only: errmsg
+  use SimModule, only: count_errors, store_error, store_error_filename
   use MemoryHelperModule, only: create_mem_path
   use BndModule, only: BndType
+  use BndExtModule, only: BndExtType
   use ObsModule, only: DefaultObsIdProcessor
-  use TimeSeriesLinkModule, only: TimeSeriesLinkType, &
-                                  GetTimeSeriesLinkFromList
   use MatrixBaseModule
   !
   implicit none
@@ -17,31 +18,36 @@ module rivmodule
   character(len=LENFTYPE) :: ftype = 'RIV'
   character(len=LENPACKAGENAME) :: text = '             RIV'
   !
-  type, extends(BndType) :: RivType
+  type, extends(BndExtType) :: RivType
+    real(DP), dimension(:), pointer, contiguous :: stage => null() !< RIV head
+    real(DP), dimension(:), pointer, contiguous :: cond => null() !< RIV bed hydraulic conductance
+    real(DP), dimension(:), pointer, contiguous :: rbot => null() !< RIV bed bottom elevation
+
   contains
-    procedure :: bnd_options => riv_options
+
+    procedure :: allocate_arrays => riv_allocate_arrays
+    procedure :: source_options => riv_options
+    procedure :: log_riv_options
+    procedure :: bnd_rp => riv_rp
     procedure :: bnd_ck => riv_ck
     procedure :: bnd_cf => riv_cf
     procedure :: bnd_fc => riv_fc
+    procedure :: bnd_da => riv_da
     procedure :: define_listlabel
+    procedure :: bound_value => riv_bound_value
+    procedure :: cond_mult
     ! -- methods for observations
     procedure, public :: bnd_obs_supported => riv_obs_supported
     procedure, public :: bnd_df_obs => riv_df_obs
-    ! -- method for time series
-    procedure, public :: bnd_rp_ts => riv_rp_ts
+    procedure, public :: riv_store_user_cond
   end type RivType
 
 contains
 
-  subroutine riv_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
-! ******************************************************************************
-! riv_create -- Create a New Riv Package
-! Subroutine: (1) create new-style package
-!             (2) point packobj to the new package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Create a New Riv Package and point packobj to the new package
+  !<
+  subroutine riv_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
+                        mempath)
     ! -- dummy
     class(BndType), pointer :: packobj
     integer(I4B), intent(in) :: id
@@ -50,16 +56,16 @@ subroutine riv_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     integer(I4B), intent(in) :: iout
     character(len=*), intent(in) :: namemodel
     character(len=*), intent(in) :: pakname
+    character(len=*), intent(in) :: mempath
     ! -- local
     type(RivType), pointer :: rivobj
-! ------------------------------------------------------------------------------
     !
     ! -- allocate the object and assign values to object variables
     allocate (rivobj)
     packobj => rivobj
     !
     ! -- create name and memory path
-    call packobj%set_names(ibcnum, namemodel, pakname, ftype)
+    call packobj%set_names(ibcnum, namemodel, pakname, ftype, mempath)
     packobj%text = text
     !
     ! -- allocate scalars
@@ -67,58 +73,147 @@ subroutine riv_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     !
     ! -- initialize package
     call packobj%pack_initialize()
-
+    !
     packobj%inunit = inunit
     packobj%iout = iout
     packobj%id = id
     packobj%ibcnum = ibcnum
-    packobj%ncolbnd = 3 ! stage, conductance, rbot
-    packobj%iscloc = 2 !sfac applies to conductance
     packobj%ictMemPath = create_mem_path(namemodel, 'NPF')
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine riv_create
 
-  subroutine riv_options(this, option, found)
-! ******************************************************************************
-! riv_options -- set options specific to RivType
-!
-! riv_options overrides BndType%bnd_options
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use InputOutputModule, only: urword
+  !> @brief Deallocate memory
+  !<
+  subroutine riv_da(this)
+    ! -- modules
+    use MemoryManagerModule, only: mem_deallocate
+    ! -- dummy
+    class(RivType) :: this
+    !
+    ! -- Deallocate parent package
+    call this%BndExtType%bnd_da()
+    !
+    ! -- arrays
+    call mem_deallocate(this%stage, 'STAGE', this%memoryPath)
+    call mem_deallocate(this%cond, 'COND', this%memoryPath)
+    call mem_deallocate(this%rbot, 'RBOT', this%memoryPath)
+    !
+    ! -- Return
+    return
+  end subroutine riv_da
+
+  !> @brief Set options specific to RivType
+  !<
+  subroutine riv_options(this)
+    ! -- modules
+    use MemoryManagerExtModule, only: mem_set_value
+    use CharacterStringModule, only: CharacterStringType
+    use GwfRivInputModule, only: GwfRivParamFoundType
     ! -- dummy
     class(RivType), intent(inout) :: this
-    character(len=*), intent(inout) :: option
-    logical, intent(inout) :: found
     ! -- local
-! ------------------------------------------------------------------------------
+    type(GwfRivParamFoundType) :: found
     !
-    select case (option)
-    case ('MOVER')
-      this%imover = 1
-      write (this%iout, '(4x,A)') 'MOVER OPTION ENABLED'
-      found = .true.
-    case default
-      !
-      ! -- No options found
-      found = .false.
-    end select
+    ! -- source base class options
+    call this%BndExtType%source_options()
+    !
+    ! -- source options from input context
+    call mem_set_value(this%imover, 'MOVER', this%input_mempath, found%mover)
+    !
+    ! -- log riv specific options
+    call this%log_riv_options(found)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine riv_options
 
+  !> @brief Log options specific to RivType
+  !<
+  subroutine log_riv_options(this, found)
+    ! -- modules
+    use GwfRivInputModule, only: GwfRivParamFoundType
+    ! -- dummy variables
+    class(RivType), intent(inout) :: this !< BndExtType object
+    type(GwfRivParamFoundType), intent(in) :: found
+    !
+    ! -- log found options
+    write (this%iout, '(/1x,a)') 'PROCESSING '//trim(adjustl(this%text)) &
+      //' OPTIONS'
+    !
+    if (found%mover) then
+      write (this%iout, '(4x,A)') 'MOVER OPTION ENABLED'
+    end if
+    !
+    ! -- close logging block
+    write (this%iout, '(1x,a)') &
+      'END OF '//trim(adjustl(this%text))//' OPTIONS'
+    !
+    ! -- Return
+    return
+  end subroutine log_riv_options
+
+  !> @brief Allocate package arrays
+  !<
+  subroutine riv_allocate_arrays(this, nodelist, auxvar)
+    ! -- modules
+    use MemoryManagerModule, only: mem_allocate, mem_setptr, mem_checkin
+    ! -- dummy
+    class(RivType) :: this
+    integer(I4B), dimension(:), pointer, contiguous, optional :: nodelist
+    real(DP), dimension(:, :), pointer, contiguous, optional :: auxvar
+    !
+    ! -- call base type allocate arrays
+    call this%BndExtType%allocate_arrays(nodelist, auxvar)
+    !
+    ! -- set riv input context pointers
+    call mem_setptr(this%stage, 'STAGE', this%input_mempath)
+    call mem_setptr(this%cond, 'COND', this%input_mempath)
+    call mem_setptr(this%rbot, 'RBOT', this%input_mempath)
+    !
+    ! --checkin riv input context pointers
+    call mem_checkin(this%stage, 'STAGE', this%memoryPath, &
+                     'STAGE', this%input_mempath)
+    call mem_checkin(this%cond, 'COND', this%memoryPath, &
+                     'COND', this%input_mempath)
+    call mem_checkin(this%rbot, 'RBOT', this%memoryPath, &
+                     'RBOT', this%input_mempath)
+    !
+    ! -- Return
+    return
+  end subroutine riv_allocate_arrays
+
+  !> @brief Read and prepare
+  !<
+  subroutine riv_rp(this)
+    ! -- modules
+    use TdisModule, only: kper
+    ! -- dummy
+    class(RivType), intent(inout) :: this
+    !
+    if (this%iper /= kper) return
+    !
+    ! -- Call the parent class read and prepare
+    call this%BndExtType%bnd_rp()
+    !
+    ! -- store user cond
+    if (this%ivsc == 1) then
+      call this%riv_store_user_cond()
+    end if
+    !
+    ! -- Write the list to iout if requested
+    if (this%iprpak /= 0) then
+      call this%write_list()
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine riv_rp
+
+  !> @brief Check river boundary condition data
+  !<
   subroutine riv_ck(this)
-! ******************************************************************************
-! riv_ck -- Check river boundary condition data
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error, count_errors, store_error_unit
@@ -141,14 +236,13 @@ subroutine riv_ck(this)
     character(len=*), parameter :: fmtriverr3 = &
       "('RIV BOUNDARY (',i0,') RIVER STAGE (',f10.4,') IS LESS &
       &THAN CELL BOTTOM (',f10.4,')')"
-! ------------------------------------------------------------------------------
     !
     ! -- check stress period data
     do i = 1, this%nbound
       node = this%nodelist(i)
       bt = this%dis%bot(node)
-      stage = this%bound(1, i)
-      rbot = this%bound(3, i)
+      stage = this%stage(i)
+      rbot = this%rbot(i)
       ! -- accumulate errors
       if (rbot < bt .and. this%icelltype(node) /= 0) then
         write (errmsg, fmt=fmtriverr) i, rbot, bt
@@ -169,38 +263,24 @@ subroutine riv_ck(this)
       call store_error_unit(this%inunit)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine riv_ck
 
-  subroutine riv_cf(this, reset_mover)
-! ******************************************************************************
-! riv_cf -- Formulate the HCOF and RHS terms
-! Subroutine: (1) skip in no rivs
-!             (2) calculate hcof and rhs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Formulate the HCOF and RHS terms
+  !!
+  !! Skip in no rivs, otherwise calculate hcof and rhs
+  !<
+  subroutine riv_cf(this)
     ! -- dummy
     class(RivType) :: this
-    logical, intent(in), optional :: reset_mover
     ! -- local
     integer(I4B) :: i, node
     real(DP) :: hriv, criv, rbot
-    logical :: lrm
-! ------------------------------------------------------------------------------
     !
     ! -- Return if no rivs
     if (this%nbound .eq. 0) return
     !
-    ! -- pakmvrobj cf
-    lrm = .true.
-    if (present(reset_mover)) lrm = reset_mover
-    if (this%imover == 1 .and. lrm) then
-      call this%pakmvrobj%cf()
-    end if
-    !
     ! -- Calculate hcof and rhs for each riv entry
     do i = 1, this%nbound
       node = this%nodelist(i)
@@ -209,9 +289,9 @@ subroutine riv_cf(this, reset_mover)
         this%rhs(i) = DZERO
         cycle
       end if
-      hriv = this%bound(1, i)
-      criv = this%bound(2, i)
-      rbot = this%bound(3, i)
+      hriv = this%stage(i)
+      criv = this%cond_mult(i)
+      rbot = this%rbot(i)
       if (this%xnew(node) <= rbot) then
         this%rhs(i) = -criv * (hriv - rbot)
         this%hcof(i) = DZERO
@@ -221,17 +301,13 @@ subroutine riv_cf(this, reset_mover)
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine riv_cf
 
+  !> @brief Copy rhs and hcof into solution rhs and amat
+  !<
   subroutine riv_fc(this, rhs, ia, idxglo, matrix_sln)
-! **************************************************************************
-! riv_fc -- Copy rhs and hcof into solution rhs and amat
-! **************************************************************************
-!
-!    SPECIFICATIONS:
-! --------------------------------------------------------------------------
     ! -- dummy
     class(RivType) :: this
     real(DP), dimension(:), intent(inout) :: rhs
@@ -241,7 +317,6 @@ subroutine riv_fc(this, rhs, ia, idxglo, matrix_sln)
     ! -- local
     integer(I4B) :: i, n, ipos
     real(DP) :: cond, stage, qriv !, rbot
-! --------------------------------------------------------------------------
     !
     ! -- pakmvrobj fc
     if (this%imover == 1) then
@@ -257,28 +332,24 @@ subroutine riv_fc(this, rhs, ia, idxglo, matrix_sln)
       !
       ! -- If mover is active and this river cell is discharging,
       !    store available water (as positive value).
-      stage = this%bound(1, i)
+      stage = this%stage(i)
       if (this%imover == 1 .and. this%xnew(n) > stage) then
-        cond = this%bound(2, i)
+        cond = this%cond_mult(i)
         qriv = cond * (this%xnew(n) - stage)
         call this%pakmvrobj%accumulate_qformvr(i, qriv)
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine riv_fc
 
+  !> @brief Define the list heading that is written to iout when PRINT_INPUT
+  !! option is used.
+  !<
   subroutine define_listlabel(this)
-! ******************************************************************************
-! define_listlabel -- Define the list heading that is written to iout when
-!   PRINT_INPUT option is used.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     class(RivType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- create the header list label
     this%listlabel = trim(this%filtyp)//' NO.'
@@ -299,43 +370,38 @@ subroutine define_listlabel(this)
       write (this%listlabel, '(a, a16)') trim(this%listlabel), 'BOUNDARY NAME'
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine define_listlabel
 
   ! -- Procedures related to observations
 
+  !> @brief Return true because RIV package supports observations
+  !!
+  !! Return true because RIV package supports observations.
+  !>
   logical function riv_obs_supported(this)
-! ******************************************************************************
-! riv_obs_supported
-!   -- Return true because RIV package supports observations.
-!   -- Overrides BndType%bnd_obs_supported()
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     implicit none
+    ! -- dummy
     class(RivType) :: this
-! ------------------------------------------------------------------------------
+    !
     riv_obs_supported = .true.
+    !
+    ! -- Return
     return
   end function riv_obs_supported
 
+  !> @brief Store observation type supported by RIV package
+  !!
+  !! Overrides BndType%bnd_df_obs
+  !<
   subroutine riv_df_obs(this)
-    ! ******************************************************************************
-    ! riv_df_obs (implements bnd_df_obs)
-    !   -- Store observation type supported by RIV package.
-    !   -- Overrides BndType%bnd_df_obs
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
     implicit none
     ! -- dummy
     class(RivType) :: this
     ! -- local
     integer(I4B) :: indx
-    ! ------------------------------------------------------------------------------
+    !
     call this%obs%StoreObsType('riv', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => DefaultObsIdProcessor
     !
@@ -344,39 +410,76 @@ subroutine riv_df_obs(this)
     call this%obs%StoreObsType('to-mvr', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => DefaultObsIdProcessor
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine riv_df_obs
 
-  ! -- Procedure related to time series
-
-  subroutine riv_rp_ts(this)
-    ! -- Assign tsLink%Text appropriately for
-    !    all time series in use by package.
-    !    In RIV package variables STAGE, COND, and RBOT
-    !    can be controlled by time series.
+  !> @brief Store user-specified conductance value
+  !<
+  subroutine riv_store_user_cond(this)
     ! -- dummy
-    class(RivType), intent(inout) :: this
+    class(RivType), intent(inout) :: this !< BndExtType object
     ! -- local
-    integer(I4B) :: i, nlinks
-    type(TimeSeriesLinkType), pointer :: tslink => null()
-    !
-    nlinks = this%TsManager%boundtslinks%Count()
-    do i = 1, nlinks
-      tslink => GetTimeSeriesLinkFromList(this%TsManager%boundtslinks, i)
-      if (associated(tslink)) then
-        select case (tslink%JCol)
-        case (1)
-          tslink%Text = 'STAGE'
-        case (2)
-          tslink%Text = 'COND'
-        case (3)
-          tslink%Text = 'RBOT'
-        end select
-      end if
+    integer(I4B) :: n
+    !
+    ! -- store backup copy of conductance values
+    do n = 1, this%nbound
+      this%condinput(n) = this%cond_mult(n)
     end do
     !
+    ! -- Return
+    return
+  end subroutine riv_store_user_cond
+
+  !> @brief Apply multiplier to conductance if auxmultcol option is in use
+  !<
+  function cond_mult(this, row) result(cond)
+    ! -- modules
+    use ConstantsModule, only: DZERO
+    ! -- dummy
+    class(RivType), intent(inout) :: this !< BndExtType object
+    integer(I4B), intent(in) :: row
+    ! -- result
+    real(DP) :: cond
+    !
+    if (this%iauxmultcol > 0) then
+      cond = this%cond(row) * this%auxvar(this%iauxmultcol, row)
+    else
+      cond = this%cond(row)
+    end if
+    !
+    ! -- Return
+    return
+  end function cond_mult
+
+  !> @brief Return requested boundary value
+  !<
+  function riv_bound_value(this, col, row) result(bndval)
+    ! -- modules
+    use ConstantsModule, only: DZERO
+    ! -- dummy
+    class(RivType), intent(inout) :: this !< BndExtType object
+    integer(I4B), intent(in) :: col
+    integer(I4B), intent(in) :: row
+    ! -- result
+    real(DP) :: bndval
+    !
+    select case (col)
+    case (1)
+      bndval = this%stage(row)
+    case (2)
+      bndval = this%cond_mult(row)
+    case (3)
+      bndval = this%rbot(row)
+    case default
+      errmsg = 'Programming error. RIV bound value requested column '&
+               &'outside range of ncolbnd (3).'
+      call store_error(errmsg)
+      call store_error_filename(this%input_fname)
+    end select
+    !
+    ! -- Return
     return
-  end subroutine riv_rp_ts
+  end function riv_bound_value
 
 end module rivmodule
diff --git a/src/Model/GroundWaterFlow/gwf3riv8idm.f90 b/src/Model/GroundWaterFlow/gwf3riv8idm.f90
new file mode 100644
index 00000000000..b32255ad30f
--- /dev/null
+++ b/src/Model/GroundWaterFlow/gwf3riv8idm.f90
@@ -0,0 +1,468 @@
+! ** Do Not Modify! MODFLOW 6 system generated file. **
+module GwfRivInputModule
+  use ConstantsModule, only: LENVARNAME
+  use InputDefinitionModule, only: InputParamDefinitionType, &
+                                   InputBlockDefinitionType
+  private
+  public gwf_riv_param_definitions
+  public gwf_riv_aggregate_definitions
+  public gwf_riv_block_definitions
+  public GwfRivParamFoundType
+  public gwf_riv_multi_package
+
+  type GwfRivParamFoundType
+    logical :: auxiliary = .false.
+    logical :: auxmultname = .false.
+    logical :: boundnames = .false.
+    logical :: iprpak = .false.
+    logical :: iprflow = .false.
+    logical :: ipakcb = .false.
+    logical :: ts_filerecord = .false.
+    logical :: ts6 = .false.
+    logical :: filein = .false.
+    logical :: ts6_filename = .false.
+    logical :: obs_filerecord = .false.
+    logical :: obs6 = .false.
+    logical :: obs6_filename = .false.
+    logical :: mover = .false.
+    logical :: maxbound = .false.
+    logical :: cellid = .false.
+    logical :: stage = .false.
+    logical :: cond = .false.
+    logical :: rbot = .false.
+    logical :: auxvar = .false.
+    logical :: boundname = .false.
+  end type GwfRivParamFoundType
+
+  logical :: gwf_riv_multi_package = .true.
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_auxiliary = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXILIARY', & ! tag name
+    'AUXILIARY', & ! fortran variable
+    'STRING', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_auxmultname = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXMULTNAME', & ! tag name
+    'AUXMULTNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_boundnames = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'OPTIONS', & ! block
+    'BOUNDNAMES', & ! tag name
+    'BOUNDNAMES', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_iprpak = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_INPUT', & ! tag name
+    'IPRPAK', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_iprflow = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_FLOWS', & ! tag name
+    'IPRFLOW', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_ipakcb = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'OPTIONS', & ! block
+    'SAVE_FLOWS', & ! tag name
+    'IPAKCB', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_ts_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS_FILERECORD', & ! tag name
+    'TS_FILERECORD', & ! fortran variable
+    'RECORD TS6 FILEIN TS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_ts6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS6', & ! tag name
+    'TS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_filein = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'OPTIONS', & ! block
+    'FILEIN', & ! tag name
+    'FILEIN', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_ts6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS6_FILENAME', & ! tag name
+    'TS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_obs_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS_FILERECORD', & ! tag name
+    'OBS_FILERECORD', & ! fortran variable
+    'RECORD OBS6 FILEIN OBS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_obs6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6', & ! tag name
+    'OBS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_obs6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6_FILENAME', & ! tag name
+    'OBS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_mover = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'OPTIONS', & ! block
+    'MOVER', & ! tag name
+    'MOVER', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_maxbound = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'DIMENSIONS', & ! block
+    'MAXBOUND', & ! tag name
+    'MAXBOUND', & ! fortran variable
+    'INTEGER', & ! type
+    '', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_cellid = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'PERIOD', & ! block
+    'CELLID', & ! tag name
+    'CELLID', & ! fortran variable
+    'INTEGER1D', & ! type
+    'NCELLDIM', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_stage = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'PERIOD', & ! block
+    'STAGE', & ! tag name
+    'STAGE', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_cond = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'PERIOD', & ! block
+    'COND', & ! tag name
+    'COND', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_rbot = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'PERIOD', & ! block
+    'RBOT', & ! tag name
+    'RBOT', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_auxvar = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'PERIOD', & ! block
+    'AUX', & ! tag name
+    'AUXVAR', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_boundname = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'PERIOD', & ! block
+    'BOUNDNAME', & ! tag name
+    'BOUNDNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_riv_param_definitions(*) = &
+    [ &
+    gwfriv_auxiliary, &
+    gwfriv_auxmultname, &
+    gwfriv_boundnames, &
+    gwfriv_iprpak, &
+    gwfriv_iprflow, &
+    gwfriv_ipakcb, &
+    gwfriv_ts_filerecord, &
+    gwfriv_ts6, &
+    gwfriv_filein, &
+    gwfriv_ts6_filename, &
+    gwfriv_obs_filerecord, &
+    gwfriv_obs6, &
+    gwfriv_obs6_filename, &
+    gwfriv_mover, &
+    gwfriv_maxbound, &
+    gwfriv_cellid, &
+    gwfriv_stage, &
+    gwfriv_cond, &
+    gwfriv_rbot, &
+    gwfriv_auxvar, &
+    gwfriv_boundname &
+    ]
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfriv_spd = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'RIV', & ! subcomponent
+    'PERIOD', & ! block
+    'STRESS_PERIOD_DATA', & ! tag name
+    'SPD', & ! fortran variable
+    'RECARRAY CELLID STAGE COND RBOT AUX BOUNDNAME', & ! type
+    'MAXBOUND', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_riv_aggregate_definitions(*) = &
+    [ &
+    gwfriv_spd &
+    ]
+
+  type(InputBlockDefinitionType), parameter :: &
+    gwf_riv_block_definitions(*) = &
+    [ &
+    InputBlockDefinitionType( &
+    'OPTIONS', & ! blockname
+    .false., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'DIMENSIONS', & ! blockname
+    .true., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'PERIOD', & ! blockname
+    .true., & ! required
+    .true., & ! aggregate
+    .true. & ! block_variable
+    ) &
+    ]
+
+end module GwfRivInputModule
diff --git a/src/Model/GroundWaterFlow/gwf3sfr8.f90 b/src/Model/GroundWaterFlow/gwf3sfr8.f90
index 2a043350ec7..c9a4141fc9d 100644
--- a/src/Model/GroundWaterFlow/gwf3sfr8.f90
+++ b/src/Model/GroundWaterFlow/gwf3sfr8.f90
@@ -28,7 +28,7 @@ module SfrModule
   use BudgetObjectModule, only: BudgetObjectType, budgetobject_cr
   use TableModule, only: TableType, table_cr
   use ObserveModule, only: ObserveType
-  use InputOutputModule, only: extract_idnum_or_bndname
+  use InputOutputModule, only: extract_idnum_or_bndname, upcase
   use BaseDisModule, only: DisBaseType
   use SimModule, only: count_errors, store_error, store_error_unit, &
                        store_warning, deprecation_warning
@@ -844,7 +844,6 @@ subroutine sfr_read_packagedata(this)
     ! -- local variables
     character(len=LINELENGTH) :: text
     character(len=LINELENGTH) :: cellid
-    character(len=LINELENGTH) :: keyword
     character(len=10) :: cnum
     character(len=LENBOUNDNAME) :: bndName
     character(len=LENBOUNDNAME) :: bndNameTemp
@@ -904,19 +903,30 @@ subroutine sfr_read_packagedata(this)
         call this%parser%GetCellid(this%dis%ndim, cellid, flag_string=.true.)
         this%igwfnode(n) = this%dis%noder_from_cellid(cellid, this%inunit, &
                                                       this%iout, &
-                                                      flag_string=.true.)
+                                                      flag_string=.true., &
+                                                      allow_zero=.true.)
         this%igwftopnode(n) = this%igwfnode(n)
         !
         ! -- read the cellid string and determine if 'none' is specified
         if (this%igwfnode(n) < 1) then
-          call this%parser%GetStringCaps(keyword)
           this%ianynone = this%ianynone + 1
-          if (keyword /= 'NONE') then
+          call upcase(cellid)
+          if (cellid == 'NONE') then
+            call this%parser%GetStringCaps(cellid)
+            !
+            ! -- create warning message
             write (cnum, '(i0)') n
-            errmsg = 'Cell ID ('//trim(cellid)// &
-                     ') for unconnected reach '//trim(cnum)// &
-                     ' must be NONE'
-            call store_error(errmsg)
+            warnmsg = 'CELLID for unconnected reach '//trim(cnum)// &
+                      ' specified to be NONE. Unconnected reaches '// &
+                      'should be specified with a zero for each grid '// &
+                      'dimension. For example, for a DIS grid a CELLID '// &
+                      'of 0 0 0 should be specified for unconnected reaches'
+            !
+            ! -- create deprecation warning
+            call deprecation_warning('PACKAGEDATA', 'CELLID=NONE', '6.5.0', &
+                                     warnmsg, this%parser%GetUnit())
+          else
+
           end if
         end if
         ! -- get reach length
@@ -1945,14 +1955,12 @@ end subroutine sfr_ad
     !!  added to the coefficient matrix and right-hand side vector.
     !!
   !<
-  subroutine sfr_cf(this, reset_mover)
+  subroutine sfr_cf(this)
     ! -- dummy variables
     class(SfrType) :: this !< SfrType object
-    logical(LGP), intent(in), optional :: reset_mover !< boolean for resetting mover
     ! -- local variables
     integer(I4B) :: n
     integer(I4B) :: igwfnode
-    logical(LGP) :: lrm
     !
     ! -- return if no sfr reaches
     if (this%nbound == 0) return
@@ -1969,13 +1977,6 @@ subroutine sfr_cf(this, reset_mover)
       this%nodelist(n) = igwfnode
     end do
     !
-    ! -- pakmvrobj cf
-    lrm = .true.
-    if (present(reset_mover)) lrm = reset_mover
-    if (this%imover == 1 .and. lrm) then
-      call this%pakmvrobj%cf()
-    end if
-    !
     ! -- return
     return
   end subroutine sfr_cf
@@ -2694,9 +2695,11 @@ subroutine sfr_da(this)
     !
     ! -- deallocate package csv table
     if (this%ipakcsv > 0) then
-      call this%pakcsvtab%table_da()
-      deallocate (this%pakcsvtab)
-      nullify (this%pakcsvtab)
+      if (associated(this%pakcsvtab)) then
+        call this%pakcsvtab%table_da()
+        deallocate (this%pakcsvtab)
+        nullify (this%pakcsvtab)
+      end if
     end if
     !
     ! -- deallocate scalars
@@ -3833,6 +3836,10 @@ subroutine sfr_update_flows(this, n, qd, qgwf)
       do i = this%ia(n) + 1, this%ia(n + 1) - 1
         if (this%idir(i) > 0) cycle
         this%qconn(i) = DZERO
+        idiv = this%idiv(i)
+        if (idiv == 0) cycle
+        jpos = this%iadiv(n) + idiv - 1
+        this%divq(jpos) = DZERO
       end do
     end if
     !
diff --git a/src/Model/GroundWaterFlow/gwf3tvk8.f90 b/src/Model/GroundWaterFlow/gwf3tvk8.f90
index 48385d07329..e801efdbd6d 100644
--- a/src/Model/GroundWaterFlow/gwf3tvk8.f90
+++ b/src/Model/GroundWaterFlow/gwf3tvk8.f90
@@ -31,7 +31,9 @@ module TvkModule
     integer(I4B), pointer :: kchangeper => null() !< NPF last stress period in which any node K (or K22, or K33) values were changed (0 if unchanged from start of simulation)
     integer(I4B), pointer :: kchangestp => null() !< NPF last time step in which any node K (or K22, or K33) values were changed (0 if unchanged from start of simulation)
     integer(I4B), dimension(:), pointer, contiguous :: nodekchange => null() !< NPF grid array of flags indicating for each node whether its K (or K22, or K33) value changed (1) at (kchangeper, kchangestp) or not (0)
+
   contains
+
     procedure :: da => tvk_da
     procedure :: ar_set_pointers => tvk_ar_set_pointers
     procedure :: read_option => tvk_read_option
@@ -46,10 +48,9 @@ module TvkModule
   !> @brief Create a new TvkType object
   !!
   !! Create a new time-varying conductivity (TvkType) object.
-  !!
   !<
   subroutine tvk_cr(tvk, name_model, inunit, iout)
-    ! -- dummy variables
+    ! -- dummy
     type(TvkType), pointer, intent(out) :: tvk
     character(len=*), intent(in) :: name_model
     integer(I4B), intent(in) :: inunit
@@ -58,6 +59,7 @@ subroutine tvk_cr(tvk, name_model, inunit, iout)
     allocate (tvk)
     call tvk%init(name_model, 'TVK', 'TVK', inunit, iout)
     !
+    ! -- Return
     return
   end subroutine tvk_cr
 
@@ -65,12 +67,11 @@ end subroutine tvk_cr
   !!
   !! Announce package version and set array and variable pointers from the NPF
   !! package for access by TVK.
-  !!
   !<
   subroutine tvk_ar_set_pointers(this)
-    ! -- dummy variables
+    ! -- dummy
     class(TvkType) :: this
-    ! -- local variables
+    ! -- local
     character(len=LENMEMPATH) :: npfMemoryPath
     ! -- formats
     character(len=*), parameter :: fmttvk = &
@@ -92,6 +93,7 @@ subroutine tvk_ar_set_pointers(this)
     call mem_setptr(this%kchangestp, 'KCHANGESTP', npfMemoryPath)
     call mem_setptr(this%nodekchange, 'NODEKCHANGE', npfMemoryPath)
     !
+    ! -- Return
     return
   end subroutine tvk_ar_set_pointers
 
@@ -99,10 +101,9 @@ end subroutine tvk_ar_set_pointers
   !!
   !! Process a single TVK-specific option. Used when reading the OPTIONS block
   !! of the TVK package input file.
-  !!
   !<
   function tvk_read_option(this, keyword) result(success)
-    ! -- dummy variables
+    ! -- dummy
     class(TvkType) :: this
     character(len=*), intent(in) :: keyword
     ! -- return
@@ -111,6 +112,7 @@ function tvk_read_option(this, keyword) result(success)
     ! -- There are no TVK-specific options, so just return false
     success = .false.
     !
+    ! -- Return
     return
   end function tvk_read_option
 
@@ -118,10 +120,9 @@ end function tvk_read_option
   !!
   !! Return a pointer to the given node's value in the appropriate NPF array
   !! based on the given variable name string.
-  !!
   !<
   function tvk_get_pointer_to_value(this, n, varName) result(bndElem)
-    ! -- dummy variables
+    ! -- dummy
     class(TvkType) :: this
     integer(I4B), intent(in) :: n
     character(len=*), intent(in) :: varName
@@ -139,6 +140,7 @@ function tvk_get_pointer_to_value(this, n, varName) result(bndElem)
       bndElem => null()
     end select
     !
+    ! -- Return
     return
   end function tvk_get_pointer_to_value
 
@@ -146,10 +148,9 @@ end function tvk_get_pointer_to_value
   !!
   !! Deferred procedure implementation called by the TvBaseType code when a
   !! property value change occurs at (kper, kstp).
-  !!
   !<
   subroutine tvk_set_changed_at(this, kper, kstp)
-    ! -- dummy variables
+    ! -- dummy
     class(TvkType) :: this
     integer(I4B), intent(in) :: kper
     integer(I4B), intent(in) :: kstp
@@ -157,6 +158,7 @@ subroutine tvk_set_changed_at(this, kper, kstp)
     this%kchangeper = kper
     this%kchangestp = kstp
     !
+    ! -- Return
     return
   end subroutine tvk_set_changed_at
 
@@ -165,7 +167,6 @@ end subroutine tvk_set_changed_at
   !! Deferred procedure implementation called by the TvBaseType code when a
   !! new time step commences, indicating that any previously set per-node
   !! property value change flags should be reset.
-  !!
   !<
   subroutine tvk_reset_change_flags(this)
     ! -- dummy variables
@@ -178,6 +179,7 @@ subroutine tvk_reset_change_flags(this)
       this%nodekchange(i) = 0
     end do
     !
+    ! -- Return
     return
   end subroutine tvk_reset_change_flags
 
@@ -187,14 +189,13 @@ end subroutine tvk_reset_change_flags
   !! property value change occurs. Check if the property value of the given
   !! variable at the given node is invalid, and log an error if so. Update
   !! K22 and K33 values appropriately when specified as anisotropy.
-  !!
   !<
   subroutine tvk_validate_change(this, n, varName)
-    ! -- dummy variables
+    ! -- dummy
     class(TvkType) :: this
     integer(I4B), intent(in) :: n
     character(len=*), intent(in) :: varName
-    ! -- local variables
+    ! -- local
     character(len=LINELENGTH) :: cellstr
     ! -- formats
     character(len=*), parameter :: fmtkerr = &
@@ -234,16 +235,16 @@ subroutine tvk_validate_change(this, n, varName)
       end if
     end if
     !
+    ! -- Return
     return
   end subroutine tvk_validate_change
 
   !> @brief Deallocate package memory
   !!
   !! Deallocate TVK package scalars and arrays.
-  !!
   !<
   subroutine tvk_da(this)
-    ! -- dummy variables
+    ! -- dummy
     class(TvkType) :: this
     !
     ! -- Nullify pointers to other package variables
@@ -259,6 +260,7 @@ subroutine tvk_da(this)
     ! -- Deallocate parent
     call tvbase_da(this)
     !
+    ! -- Return
     return
   end subroutine tvk_da
 
diff --git a/src/Model/GroundWaterFlow/gwf3tvs8.f90 b/src/Model/GroundWaterFlow/gwf3tvs8.f90
index 390810b77e2..e516424c4fe 100644
--- a/src/Model/GroundWaterFlow/gwf3tvs8.f90
+++ b/src/Model/GroundWaterFlow/gwf3tvs8.f90
@@ -27,7 +27,9 @@ module TvsModule
     integer(I4B), pointer :: iusesy => null() !< STO flag set if any cell is convertible (0, 1)
     real(DP), dimension(:), pointer, contiguous :: ss => null() !< STO specfic storage or storage coefficient
     real(DP), dimension(:), pointer, contiguous :: sy => null() !< STO specific yield
+
   contains
+
     procedure :: da => tvs_da
     procedure :: ar_set_pointers => tvs_ar_set_pointers
     procedure :: read_option => tvs_read_option
@@ -42,10 +44,9 @@ module TvsModule
   !> @brief Create a new TvsType object
   !!
   !! Create a new time-varying storage (TVS) object.
-  !!
   !<
   subroutine tvs_cr(tvs, name_model, inunit, iout)
-    ! -- dummy variables
+    ! -- dummy
     type(TvsType), pointer, intent(out) :: tvs
     character(len=*), intent(in) :: name_model
     integer(I4B), intent(in) :: inunit
@@ -54,6 +55,7 @@ subroutine tvs_cr(tvs, name_model, inunit, iout)
     allocate (tvs)
     call tvs%init(name_model, 'TVS', 'TVS', inunit, iout)
     !
+    ! -- Return
     return
   end subroutine tvs_cr
 
@@ -61,12 +63,11 @@ end subroutine tvs_cr
   !!
   !! Announce package version, set array and variable pointers from the STO
   !! package for access by TVS, and enable storage change integration.
-  !!
   !<
   subroutine tvs_ar_set_pointers(this)
-    ! -- dummy variables
+    ! -- dummy
     class(TvsType) :: this
-    ! -- local variables
+    ! -- local
     character(len=LENMEMPATH) :: stoMemoryPath
     ! -- formats
     character(len=*), parameter :: fmttvs = &
@@ -87,6 +88,7 @@ subroutine tvs_ar_set_pointers(this)
     ! -- Instruct STO to integrate storage changes, since TVS is active
     this%integratechanges = 1
     !
+    ! -- Return
     return
   end subroutine tvs_ar_set_pointers
 
@@ -94,10 +96,9 @@ end subroutine tvs_ar_set_pointers
   !!
   !! Process a single TVS-specific option. Used when reading the OPTIONS block
   !! of the TVS package input file.
-  !!
   !<
   function tvs_read_option(this, keyword) result(success)
-    ! -- dummy variables
+    ! -- dummy
     class(TvsType) :: this
     character(len=*), intent(in) :: keyword
     ! -- return
@@ -116,6 +117,7 @@ function tvs_read_option(this, keyword) result(success)
       success = .false.
     end select
     !
+    ! -- Return
     return
   end function tvs_read_option
 
@@ -123,10 +125,9 @@ end function tvs_read_option
   !!
   !! Return a pointer to the given node's value in the appropriate STO array
   !! based on the given variable name string.
-  !!
   !<
   function tvs_get_pointer_to_value(this, n, varName) result(bndElem)
-    ! -- dummy variables
+    ! -- dummy
     class(TvsType) :: this
     integer(I4B), intent(in) :: n
     character(len=*), intent(in) :: varName
@@ -142,6 +143,7 @@ function tvs_get_pointer_to_value(this, n, varName) result(bndElem)
       bndElem => null()
     end select
     !
+    ! -- Return
     return
   end function tvs_get_pointer_to_value
 
@@ -149,10 +151,9 @@ end function tvs_get_pointer_to_value
   !!
   !! Deferred procedure implementation called by the TvBaseType code when a
   !! property value change occurs at (kper, kstp).
-  !!
   !<
   subroutine tvs_set_changed_at(this, kper, kstp)
-    ! -- dummy variables
+    ! -- dummy
     class(TvsType) :: this
     integer(I4B), intent(in) :: kper
     integer(I4B), intent(in) :: kstp
@@ -160,6 +161,7 @@ subroutine tvs_set_changed_at(this, kper, kstp)
     ! -- No need to record TVS/STO changes, as no other packages cache
     ! -- Ss or Sy values
     !
+    ! -- Return
     return
   end subroutine tvs_set_changed_at
 
@@ -168,14 +170,15 @@ end subroutine tvs_set_changed_at
   !! Deferred procedure implementation called by the TvBaseType code when a
   !! new time step commences, indicating that any previously set per-node
   !! property value change flags should be reset.
-  !!
   !<
   subroutine tvs_reset_change_flags(this)
+    ! -- dummy
     class(TvsType) :: this
     !
     ! -- No need to record TVS/STO changes, as no other packages cache
     ! -- Ss or Sy values
     !
+    ! -- Return
     return
   end subroutine tvs_reset_change_flags
 
@@ -184,14 +187,13 @@ end subroutine tvs_reset_change_flags
   !! Deferred procedure implementation called by the TvBaseType code after a
   !! property value change occurs. Check if the property value of the given
   !! variable at the given node is invalid, and log an error if so.
-  !!
   !<
   subroutine tvs_validate_change(this, n, varName)
-    ! -- dummy variables
+    ! -- dummy
     class(TvsType) :: this
     integer(I4B), intent(in) :: n
     character(len=*), intent(in) :: varName
-    ! -- local variables
+    ! -- local
     character(len=LINELENGTH) :: cellstr
     ! -- formats
     character(len=*), parameter :: fmtserr = &
@@ -223,16 +225,16 @@ subroutine tvs_validate_change(this, n, varName)
       end if
     end if
     !
+    ! -- Return
     return
   end subroutine tvs_validate_change
 
   !> @brief Deallocate package memory
   !!
   !! Deallocate TVS package scalars and arrays.
-  !!
   !<
   subroutine tvs_da(this)
-    ! -- dummy variables
+    ! -- dummy
     class(TvsType) :: this
     !
     ! -- Nullify pointers to other package variables
@@ -244,6 +246,7 @@ subroutine tvs_da(this)
     ! -- Deallocate parent
     call tvbase_da(this)
     !
+    ! -- Return
     return
   end subroutine tvs_da
 
diff --git a/src/Model/GroundWaterFlow/gwf3uzf8.f90 b/src/Model/GroundWaterFlow/gwf3uzf8.f90
index 51204499414..d8b7019fc6a 100644
--- a/src/Model/GroundWaterFlow/gwf3uzf8.f90
+++ b/src/Model/GroundWaterFlow/gwf3uzf8.f90
@@ -10,7 +10,6 @@ module UzfModule
                              DHNOFLO, DHDRY, &
                              TABLEFT, TABCENTER, TABRIGHT, &
                              TABSTRING, TABUCSTRING, TABINTEGER, TABREAL
-  use GenericUtilitiesModule, only: sim_message
   use MemoryManagerModule, only: mem_allocate, mem_reallocate, mem_setptr, &
                                  mem_deallocate
   use MemoryHelperModule, only: create_mem_path
@@ -169,15 +168,9 @@ module UzfModule
 
 contains
 
+  !> @brief Create a New UZF Package and point packobj to the new package
+  !<
   subroutine uzf_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
-! ******************************************************************************
-! uzf_create -- Create a New UZF Package
-! Subroutine: (1) create new-style package
-!             (2) point packobj to the new package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
@@ -190,7 +183,6 @@ subroutine uzf_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     character(len=*), intent(in) :: pakname
     ! -- local
     type(UzfType), pointer :: uzfobj
-! ------------------------------------------------------------------------------
     !
     ! -- allocate the object and assign values to object variables
     allocate (uzfobj)
@@ -215,17 +207,13 @@ subroutine uzf_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     packobj%isadvpak = 1
     packobj%ictMemPath = create_mem_path(namemodel, 'NPF')
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_create
 
+  !> @brief Allocate and Read
+  !<
   subroutine uzf_ar(this)
-! ******************************************************************************
-! uzf_ar -- Allocate and Read
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate, mem_setptr, mem_reallocate
     ! -- dummy
@@ -233,7 +221,6 @@ subroutine uzf_ar(this)
     ! -- local
     integer(I4B) :: n, i
     real(DP) :: hgwf
-! ------------------------------------------------------------------------------
     !
     call this%obs%obs_ar()
     !
@@ -269,24 +256,18 @@ subroutine uzf_ar(this)
       call this%pakmvrobj%ar(this%maxbound, this%maxbound, this%memoryPath)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_ar
 
+  !> @brief Allocate arrays used for uzf
+  !<
   subroutine uzf_allocate_arrays(this)
-! ******************************************************************************
-! allocate_arrays -- allocate arrays used for uzf
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(UzfType), intent(inout) :: this
     ! -- local
     integer(I4B) :: i
     integer(I4B) :: j
-! ------------------------------------------------------------------------------
     !
     ! -- call standard BndType allocate scalars (now done from AR)
     !call this%BndType%allocate_arrays()
@@ -309,11 +290,11 @@ subroutine uzf_allocate_arrays(this)
     call mem_allocate(this%rch0, this%nodes, 'RCH0', this%memoryPath)
     call mem_allocate(this%qsto, this%nodes, 'QSTO', this%memoryPath)
     call mem_allocate(this%deriv, this%nodes, 'DERIV', this%memoryPath)
-
+    !
     ! -- integer vectors
     call mem_allocate(this%ia, this%dis%nodes + 1, 'IA', this%memoryPath)
     call mem_allocate(this%ja, this%nodes, 'JA', this%memoryPath)
-
+    !
     ! -- allocate timeseries aware variables
     call mem_allocate(this%sinf, this%nodes, 'SINF', this%memoryPath)
     call mem_allocate(this%pet, this%nodes, 'PET', this%memoryPath)
@@ -324,7 +305,7 @@ subroutine uzf_allocate_arrays(this)
     call mem_allocate(this%rootact, this%nodes, 'ROOTACT', this%memoryPath)
     call mem_allocate(this%uauxvar, this%naux, this%nodes, 'UAUXVAR', &
                       this%memoryPath)
-
+    !
     ! -- initialize
     do i = 1, this%nodes
       this%appliedinf(i) = DZERO
@@ -388,20 +369,16 @@ subroutine uzf_allocate_arrays(this)
       this%qauxcbc(i) = DZERO
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_allocate_arrays
-!
 
+  !> @brief Set options specific to UzfType
+  !!
+  !! Overrides BoundaryPackageType%child_class_options
+  !<
   subroutine uzf_options(this, option, found)
-! ******************************************************************************
-! uzf_options -- set options specific to UzfType
-!
-! uzf_options overrides BoundaryPackageType%child_class_options
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use ConstantsModule, only: DZERO, MNORMAL
     use OpenSpecModule, only: access, form
     use SimModule, only: store_error
@@ -436,8 +413,6 @@ subroutine uzf_options(this, option, found)
       &a, /4x, 'OPENED ON UNIT: ', I0)"
     character(len=*), parameter :: fmtuzfopt = &
       &"(4x, 'UZF ', a, ' VALUE (',g15.7,') SPECIFIED.')"
-
-! ------------------------------------------------------------------------------
     !
     !
     found = .true.
@@ -541,26 +516,20 @@ subroutine uzf_options(this, option, found)
       ! -- No options found
       found = .false.
     end select
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_options
 !
+  !> @brief Set dimensions specific to UzfType
+  !<
   subroutine uzf_readdimensions(this)
-! ******************************************************************************
-! uzf_readdimensions -- set dimensions specific to UzfType
-!
-! uzf_readdimensions BoundaryPackageType%readdimensions
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use InputOutputModule, only: urword
     use SimModule, only: store_error, count_errors
     class(uzftype), intent(inout) :: this
     character(len=LINELENGTH) :: keyword
     integer(I4B) :: ierr
     logical :: isfound, endOfBlock
-! ------------------------------------------------------------------------------
     !
     ! -- initialize dimensions to -1
     this%nodes = -1
@@ -659,20 +628,17 @@ subroutine uzf_readdimensions(this)
     ! -- setup the budget object
     call this%uzf_setup_budobj()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_readdimensions
 
+  !> @brief Read stress data
+  !!
+  !!  - check if bc changes
+  !!  - read new bc for stress period
+  !!  - set kinematic variables to bc values
+  !<
   subroutine uzf_rp(this)
-! ******************************************************************************
-! uzf_rp -- Read stress data
-! Subroutine: (1) check if bc changes
-!             (2) read new bc for stress period
-!             (3) set kinematic variables to bc values
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: kper, nper
     use TimeSeriesManagerModule, only: read_value_or_time_series_adv
@@ -708,7 +674,6 @@ subroutine uzf_rp(this)
       &WHENEVER ICBCFL IS NOT ZERO.')"
     character(len=*), parameter :: fmtflow = &
       &"(4x, 'FLOWS WILL BE SAVED TO FILE: ', a, /4x, 'OPENED ON UNIT: ', I7)"
-! ------------------------------------------------------------------------------
     !
     ! -- Set ionper to the stress period number for which a new block of data
     !    will be read.
@@ -958,17 +923,13 @@ subroutine uzf_rp(this)
     ! -- Save old ss flag
     this%issflagold = this%issflag
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_rp
 
+  !> @brief Advance UZF Package
+  !<
   subroutine uzf_ad(this)
-! ******************************************************************************
-! uzf_ad -- Advance UZF Package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SimVariablesModule, only: iFailedStepRetry
     ! -- dummy
@@ -978,7 +939,6 @@ subroutine uzf_ad(this)
     integer(I4B) :: ivertflag
     integer(I4B) :: n, iaux
     real(DP) :: rval1, rval2, rval3
-! ------------------------------------------------------------------------------
     !
     ! -- Advance the time series
     call this%TsManager%ad()
@@ -1069,23 +1029,17 @@ subroutine uzf_ad(this)
     return
   end subroutine uzf_ad
 
-  subroutine uzf_cf(this, reset_mover)
-! ******************************************************************************
-! uzf_cf -- Formulate the HCOF and RHS terms
-! Subroutine: (1) skip if no UZF cells
-!             (2) calculate hcof and rhs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Formulate the HCOF and RHS terms
+  !!
+  !!   - skip if no UZF cells
+  !!   - calculate hcof and rhs
+  !<
+  subroutine uzf_cf(this)
     ! -- modules
     ! -- dummy
     class(UzfType) :: this
-    logical, intent(in), optional :: reset_mover
     ! -- locals
     integer(I4B) :: n
-    logical :: lrm
-! ------------------------------------------------------------------------------
     !
     ! -- Return if no UZF cells
     if (this%nodes == 0) return
@@ -1098,24 +1052,13 @@ subroutine uzf_cf(this, reset_mover)
       this%gwd0(n) = this%gwd(n)
     end do
     !
-    ! -- pakmvrobj cf
-    lrm = .true.
-    if (present(reset_mover)) lrm = reset_mover
-    if (this%imover == 1 .and. lrm) then
-      call this%pakmvrobj%cf()
-    end if
-    !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_cf
 
+  !> @brief Copy rhs and hcof into solution rhs and amat
+  !<
   subroutine uzf_fc(this, rhs, ia, idxglo, matrix_sln)
-! ******************************************************************************
-! uzf_fc -- Copy rhs and hcof into solution rhs and amat
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(UzfType) :: this
     real(DP), dimension(:), intent(inout) :: rhs
@@ -1124,7 +1067,6 @@ subroutine uzf_fc(this, rhs, ia, idxglo, matrix_sln)
     class(MatrixBaseType), pointer :: matrix_sln
     ! -- local
     integer(I4B) :: i, n, ipos
-! ------------------------------------------------------------------------------
     !
     ! -- pakmvrobj fc
     if (this%imover == 1) then
@@ -1143,17 +1085,13 @@ subroutine uzf_fc(this, rhs, ia, idxglo, matrix_sln)
       call matrix_sln%add_value_pos(idxglo(ipos), this%hcof(i))
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_fc
-!
+
+  !> @brief Fill newton terms
+  !<
   subroutine uzf_fn(this, rhs, ia, idxglo, matrix_sln)
-! **************************************************************************
-! uzf_fn -- Fill newton terms
-! **************************************************************************
-!
-!    SPECIFICATIONS:
-! --------------------------------------------------------------------------
     ! -- dummy
     class(UzfType) :: this
     real(DP), dimension(:), intent(inout) :: rhs
@@ -1163,7 +1101,6 @@ subroutine uzf_fn(this, rhs, ia, idxglo, matrix_sln)
     ! -- local
     integer(I4B) :: i, n
     integer(I4B) :: ipos
-! --------------------------------------------------------------------------
     !
     ! -- Add derivative terms to rhs and amat
     do i = 1, this%nodes
@@ -1173,17 +1110,14 @@ subroutine uzf_fn(this, rhs, ia, idxglo, matrix_sln)
       rhs(n) = rhs(n) + this%deriv(i) * this%xnew(n)
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_fn
 
+  !> @brief Final convergence check for package
+  !<
   subroutine uzf_cc(this, innertot, kiter, iend, icnvgmod, cpak, ipak, dpak)
-! **************************************************************************
-! uzf_cc -- Final convergence check for package
-! **************************************************************************
-!
-!    SPECIFICATIONS:
-! --------------------------------------------------------------------------
+    ! -- modules
     use TdisModule, only: totim, kstp, kper, delt
     ! -- dummy
     class(Uzftype), intent(inout) :: this
@@ -1217,8 +1151,6 @@ subroutine uzf_cc(this, innertot, kiter, iend, icnvgmod, cpak, ipak, dpak)
     real(DP) :: dseepmax
     real(DP) :: dqfrommvr
     real(DP) :: dqfrommvrmax
-    ! format
-! --------------------------------------------------------------------------
     !
     ! -- initialize local variables
     icheck = this%iconvchk
@@ -1409,17 +1341,13 @@ subroutine uzf_cc(this, innertot, kiter, iend, icnvgmod, cpak, ipak, dpak)
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_cc
 
+  !> @brief Calculate flows
+  !<
   subroutine uzf_cq(this, x, flowja, iadv)
-! **************************************************************************
-! uzf_cq -- Calculate flows
-! **************************************************************************
-!
-!    SPECIFICATIONS:
-! --------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: delt
     use ConstantsModule, only: LENBOUNDNAME, DZERO, DHNOFLO, DHDRY
@@ -1440,7 +1368,6 @@ subroutine uzf_cq(this, x, flowja, iadv)
     ! -- formats
     character(len=*), parameter :: fmttkk = &
       &"(1X,/1X,A,'   PERIOD ',I0,'   STEP ',I0)"
-! ------------------------------------------------------------------------------
     !
     ! -- Make uzf solution for budget calculations, and then reset waves.
     !    Final uzf solve will be done as part of ot().
@@ -1518,12 +1445,13 @@ subroutine uzf_cq(this, x, flowja, iadv)
     ! -- fill the budget object
     call this%uzf_fill_budobj()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_cq
 
   function get_storage_change(top, bot, carea, hold, hnew, wcold, wcnew, &
                               thtr, delt, iss) result(qsto)
+    ! -- dummy
     real(DP), intent(in) :: top
     real(DP), intent(in) :: bot
     real(DP), intent(in) :: hold
@@ -1534,7 +1462,9 @@ function get_storage_change(top, bot, carea, hold, hnew, wcold, wcnew, &
     real(DP), intent(in) :: carea
     real(DP), intent(in) :: delt
     integer(I4B) :: iss
+    ! -- return
     real(DP) :: qsto
+    ! -- local
     real(DP) :: thknew
     real(DP) :: thkold
     if (iss == 0) then
@@ -1551,9 +1481,13 @@ function get_storage_change(top, bot, carea, hold, hnew, wcold, wcnew, &
     else
       qsto = DZERO
     end if
+    !
+    ! -- Return
     return
   end function get_storage_change
 
+  !> @brief Add package ratin/ratout to model budget
+  !<
   subroutine uzf_bd(this, model_budget)
     ! -- add package ratin/ratout to model budget
     use TdisModule, only: delt
@@ -1564,12 +1498,12 @@ subroutine uzf_bd(this, model_budget)
     real(DP) :: ratout
     integer(I4B) :: isuppress_output
     isuppress_output = 0
-
+    !
     ! -- Calculate flow from uzf to gwf (UZF-GWRCH)
     call rate_accumulator(this%rch, ratin, ratout)
     call model_budget%addentry(ratin, ratout, delt, this%bdtxt(2), &
                                isuppress_output, this%packName)
-
+    !
     ! -- GW discharge and GW discharge to mover
     if (this%iseepflag == 1) then
       call rate_accumulator(-this%gwd, ratin, ratout)
@@ -1581,24 +1515,21 @@ subroutine uzf_bd(this, model_budget)
                                    isuppress_output, this%packName)
       end if
     end if
-
+    !
     ! -- groundwater et (gwet array is positive, so switch ratin/ratout)
     if (this%igwetflag /= 0) then
       call rate_accumulator(-this%gwet, ratin, ratout)
       call model_budget%addentry(ratin, ratout, delt, this%bdtxt(4), &
                                  isuppress_output, this%packName)
     end if
-
+    !
+    ! -- Return
     return
   end subroutine uzf_bd
 
+  !> @brief Write flows to binary file and/or print flows to budget
+  !<
   subroutine uzf_ot_model_flows(this, icbcfl, ibudfl, icbcun, imap)
-! ******************************************************************************
-! bnd_ot_model_flows -- write flows to binary file and/or print flows to budget
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LENBOUNDNAME, DZERO
     use BndModule, only: save_print_model_flows
@@ -1611,8 +1542,6 @@ subroutine uzf_ot_model_flows(this, icbcfl, ibudfl, icbcun, imap)
     ! -- local
     character(len=LINELENGTH) :: title
     integer(I4B) :: itxt
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- UZF-GWRCH
     itxt = 2
@@ -1672,12 +1601,16 @@ subroutine uzf_ot_model_flows(this, icbcfl, ibudfl, icbcun, imap)
                                   this%boundname)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_ot_model_flows
 
+  !> @brief Output UZF package flow terms
+  !<
   subroutine uzf_ot_package_flows(this, icbcfl, ibudfl)
+    ! -- modules
     use TdisModule, only: kstp, kper, delt, pertim, totim
+    ! -- dummy
     class(UzfType) :: this
     integer(I4B), intent(in) :: icbcfl
     integer(I4B), intent(in) :: ibudfl
@@ -1698,15 +1631,22 @@ subroutine uzf_ot_package_flows(this, icbcfl, ibudfl)
     if (ibudfl /= 0 .and. this%iprflow /= 0) then
       call this%budobj%write_flowtable(this%dis, kstp, kper)
     end if
-
+    !
+    ! -- Return
+    return
   end subroutine uzf_ot_package_flows
 
+  !> @brief Save UZF-calculated values to binary file
+  !<
   subroutine uzf_ot_dv(this, idvsave, idvprint)
+    ! -- modules
     use TdisModule, only: kstp, kper, pertim, totim
+    ! -- dummy
     use InputOutputModule, only: ulasav
     class(UzfType) :: this
     integer(I4B), intent(in) :: idvsave
     integer(I4B), intent(in) :: idvprint
+    ! -- local
     integer(I4B) :: ibinun
     !
     ! -- set unit number for binary dependent variable output
@@ -1721,8 +1661,13 @@ subroutine uzf_ot_dv(this, idvsave, idvprint)
       call ulasav(this%wcnew, '   WATER-CONTENT', kstp, kper, pertim, &
                   totim, this%nodes, 1, 1, ibinun)
     end if
+    !
+    ! -- Return
+    return
   end subroutine uzf_ot_dv
 
+  !> @brief Write UZF budget to listing file
+  !<
   subroutine uzf_ot_bdsummary(this, kstp, kper, iout, ibudfl)
     ! -- module
     use TdisModule, only: totim
@@ -1735,17 +1680,13 @@ subroutine uzf_ot_bdsummary(this, kstp, kper, iout, ibudfl)
     !
     call this%budobj%write_budtable(kstp, kper, iout, ibudfl, totim)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_ot_bdsummary
 
+  !> @brief Formulate the HCOF and RHS terms
+  !<
   subroutine uzf_solve(this, reset_state)
-! ******************************************************************************
-! uzf_solve -- Formulate the HCOF and RHS terms
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: delt
     logical, intent(in) :: reset_state !< flag indicating that waves should be reset after solution
@@ -1760,7 +1701,6 @@ subroutine uzf_solve(this, reset_state)
     real(DP) :: qformvr
     real(DP) :: wc
     real(DP) :: watabold
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize
     ierr = 0
@@ -1862,20 +1802,16 @@ subroutine uzf_solve(this, reset_state)
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_solve
 
+  !> @brief Define the list heading that is written to iout when PRINT_INPUT
+  !!  option is used
+  !<
   subroutine define_listlabel(this)
-! ******************************************************************************
-! define_listlabel -- Define the list heading that is written to iout when
-!   PRINT_INPUT option is used.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     class(UzfType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- create the header list label
     this%listlabel = trim(this%filtyp)//' NO.'
@@ -1894,18 +1830,21 @@ subroutine define_listlabel(this)
       write (this%listlabel, '(a, a16)') trim(this%listlabel), 'BOUNDARY NAME'
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine define_listlabel
 
+  !> @brief Identify overlying cell ID based on user-specified mapping
+  !<
   subroutine findcellabove(this, n, nml)
+    ! -- dummy
     class(UzfType) :: this
     integer(I4B), intent(in) :: n
     integer(I4B), intent(inout) :: nml
+    ! -- local
     integer(I4B) :: m, ipos
-! ------------------------------------------------------------------------------
-!
-    ! -- return nml = n if no cell is above it
+    !
+    ! -- Return nml = n if no cell is above it
     nml = n
     do ipos = this%dis%con%ia(n) + 1, this%dis%con%ia(n + 1) - 1
       m = this%dis%con%ja(ipos)
@@ -1918,17 +1857,17 @@ subroutine findcellabove(this, n, nml)
         end if
       end if
     end do
+    !
+    ! -- Return
     return
   end subroutine findcellabove
 
+  !> @brief Read UZF cell properties and set them for UzfCellGroup type
+  !<
   subroutine read_cell_properties(this)
-! ******************************************************************************
-! read_cell_properties -- Read UZF cell properties and set them for
-!                         UzfCellGroup type.
-! ******************************************************************************
+    ! -- modules
     use InputOutputModule, only: urword
     use SimModule, only: store_error, count_errors
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(UzfType), intent(inout) :: this
     ! -- local
@@ -1945,8 +1884,6 @@ subroutine read_cell_properties(this)
     integer(I4B), dimension(:), allocatable :: rowmaxnnz
     type(sparsematrix) :: sparse
     integer(I4B), dimension(:), allocatable :: nboundchk
-! ------------------------------------------------------------------------------
-!
     !
     ! -- allocate space for node counter and initilize
     allocate (rowmaxnnz(this%dis%nodes))
@@ -2158,16 +2095,13 @@ subroutine read_cell_properties(this)
     deallocate (rowmaxnnz)
     deallocate (nboundchk)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine read_cell_properties
 
+  !> @brief Read UZF cell properties and set them for UZFCellGroup type
+  !<
   subroutine print_cell_properties(this)
-! ******************************************************************************
-! print_cell_properties -- Read UZF cell properties and set them for
-!                          UZFCellGroup type.
-! ******************************************************************************
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(UzfType), intent(inout) :: this
     ! -- local
@@ -2178,8 +2112,6 @@ subroutine print_cell_properties(this)
     integer(I4B) :: ntabcols
     integer(I4B) :: i
     integer(I4B) :: node
-! ------------------------------------------------------------------------------
-!
     !
     ! -- setup inputtab tableobj
     !
@@ -2247,17 +2179,16 @@ subroutine print_cell_properties(this)
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine print_cell_properties
 
+  !> @brief Check UZF cell areas
+  !<
   subroutine check_cell_area(this)
-! ******************************************************************************
-! check_cell_area -- Check UZF cell areas.
-! ******************************************************************************
+    ! -- modules
     use InputOutputModule, only: urword
     use SimModule, only: store_error, count_errors
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(UzfType) :: this
     ! -- local
@@ -2275,8 +2206,6 @@ subroutine check_cell_area(this)
     real(DP) :: sumarea
     real(DP) :: cellarea
     real(DP) :: d
-! ------------------------------------------------------------------------------
-!
     !
     ! -- check that the area of vertically connected uzf cells is the equal
     do i = 1, this%nodes
@@ -2331,40 +2260,36 @@ subroutine check_cell_area(this)
     if (count_errors() > 0) then
       call this%parser%StoreErrorUnit()
     end if
-    ! -- return
+    ! -- Return
     return
   end subroutine check_cell_area
 
   ! -- Procedures related to observations (type-bound)
+
+  !> @brief Return true because uzf package supports observations
+  !!
+  !! Overrides BndType%bnd_obs_supported
+  !<
   logical function uzf_obs_supported(this)
-! ******************************************************************************
-! uzf_obs_supported
-!   -- Return true because uzf package supports observations.
-!   -- Overrides BndType%bnd_obs_supported
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     class(UzfType) :: this
-! ------------------------------------------------------------------------------
+    !
     uzf_obs_supported = .true.
+    !
+    ! -- Return
     return
   end function uzf_obs_supported
 
+  !> @brief Implements bnd_df_obs
+  !!
+  !! Store observation type supported by uzf package.
+  !! Overrides BndType%bnd_df_obs
+  !<
   subroutine uzf_df_obs(this)
-! ******************************************************************************
-! uzf_df_obs (implements bnd_df_obs)
-!   -- Store observation type supported by uzf package.
-!   -- Overrides BndType%bnd_df_obs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(UzfType) :: this
     ! -- local
     integer(I4B) :: indx
-    ! ------------------------------------------------------------------------------
     !
     ! -- Store obs type and assign procedure pointer
     !
@@ -2416,19 +2341,14 @@ subroutine uzf_df_obs(this)
     call this%obs%StoreObsType('water-content', .false., indx)
     this%obs%obsData(indx)%ProcessIdPtr => uzf_process_obsID
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_df_obs
-!
+
+  !> @brief Calculate observations this time step and call ObsType%SaveOneSimval
+  !! for each UzfType observation
+  !<
   subroutine uzf_bd_obs(this)
-    ! **************************************************************************
-    ! uzf_bd_obs
-    !   -- Calculate observations this time step and call
-    !      ObsType%SaveOneSimval for each UzfType observation.
-    ! **************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! --------------------------------------------------------------------------
     ! -- dummy
     class(UzfType) :: this
     ! -- local
@@ -2437,7 +2357,6 @@ subroutine uzf_bd_obs(this)
     integer(I4B) :: n
     real(DP) :: v
     type(ObserveType), pointer :: obsrv => null()
-    !---------------------------------------------------------------------------
     !
     ! -- Make final uzf solution, and do not reset waves.  This will advance
     !    the waves to their new state at the end of the time step.  This should
@@ -2519,11 +2438,17 @@ subroutine uzf_bd_obs(this)
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_bd_obs
-!
+
+  !> @brief Process each observation
+  !!
+  !! Only done the first stress period since boundaries are fixed for the
+  !! simulation
+  !<
   subroutine uzf_rp_obs(this)
+    ! -- modules
     use TdisModule, only: kper
     ! -- dummy
     class(UzfType), intent(inout) :: this
@@ -2537,13 +2462,9 @@ subroutine uzf_rp_obs(this)
     real(DP) :: dmax
     character(len=LENBOUNDNAME) :: bname
     class(ObserveType), pointer :: obsrv => null()
-    ! --------------------------------------------------------------------------
     ! -- formats
 60  format('Invalid node number in OBS input: ', i0)
     !
-    ! -- process each package observation
-    !    only done the first stress period since boundaries are fixed
-    !    for the simulation
     if (kper == 1) then
       do i = 1, this%obs%npakobs
         obsrv => this%obs%pakobs(i)%obsrv
@@ -2642,13 +2563,19 @@ subroutine uzf_rp_obs(this)
       end if
     end if
     !
+    ! -- Return
     return
   end subroutine uzf_rp_obs
-  !
+
   ! -- Procedures related to observations (NOT type-bound)
+
+  !> @brief This procedure is pointed to by ObsDataType%ProcesssIdPtr
+  !!
+  !! Process the ID string of an observation definition for UZF-package
+  !! observations
+  !<
   subroutine uzf_process_obsID(obsrv, dis, inunitobs, iout)
-    ! -- This procedure is pointed to by ObsDataType%ProcesssIdPtr. It processes
-    !    the ID string of an observation definition for UZF-package observations.
+    ! -- .
     ! -- dummy
     type(ObserveType), intent(inout) :: obsrv
     class(DisBaseType), intent(in) :: dis
@@ -2693,22 +2620,17 @@ subroutine uzf_process_obsID(obsrv, dis, inunitobs, iout)
       obsrv%Obsdepth = obsdepth
     end if
     !
+    ! -- Return
     return
   end subroutine uzf_process_obsID
 
+  !> @brief Allocate scalar members
+  !<
   subroutine uzf_allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars -- allocate scalar members
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
-
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(UzfType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- call standard BndType allocate scalars
     call this%BndType%allocate_scalars()
@@ -2736,7 +2658,7 @@ subroutine uzf_allocate_scalars(this)
     call mem_allocate(this%igwetflag, 'IGWETFLAG', this%memoryPath)
     call mem_allocate(this%iuzf2uzf, 'IUZF2UZF', this%memoryPath)
     call mem_allocate(this%cbcauxitems, 'CBCAUXITEMS', this%memoryPath)
-
+    !
     call mem_allocate(this%iconvchk, 'ICONVCHK', this%memoryPath)
     !
     ! -- initialize scalars
@@ -2761,30 +2683,24 @@ subroutine uzf_allocate_scalars(this)
     ! -- convergence check
     this%iconvchk = 1
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_allocate_scalars
-!
+
+  !> @brief Deallocate objects
+  !<
   subroutine uzf_da(this)
-! ******************************************************************************
-! uzf_da -- Deallocate objects
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(UzfType) :: this
-    ! -- locals
-    ! -- format
-! ------------------------------------------------------------------------------
     !
     ! -- deallocate uzf objects
     call this%uzfobj%dealloc()
     deallocate (this%uzfobj)
     nullify (this%uzfobj)
     call this%uzfobjwork%dealloc()
-
+    !
     call this%budobj%budgetobject_da()
     deallocate (this%budobj)
     nullify (this%budobj)
@@ -2796,9 +2712,11 @@ subroutine uzf_da(this)
     !
     ! -- package csv table
     if (this%ipakcsv > 0) then
-      call this%pakcsvtab%table_da()
-      deallocate (this%pakcsvtab)
-      nullify (this%pakcsvtab)
+      if (associated(this%pakcsvtab)) then
+        call this%pakcsvtab%table_da()
+        deallocate (this%pakcsvtab)
+        nullify (this%pakcsvtab)
+      end if
     end if
     !
     ! -- deallocate scalars
@@ -2869,15 +2787,12 @@ subroutine uzf_da(this)
     return
   end subroutine uzf_da
 
+  !> @brief Set up the budget object that stores all the uzf flows
+  !!
+  !! The terms listed here must correspond in number and order to the ones
+  !! listed in the uzf_fill_budobj routine
+  !<
   subroutine uzf_setup_budobj(this)
-! ******************************************************************************
-! uzf_setup_budobj -- Set up the budget object that stores all the uzf flows
-!   The terms listed here must correspond in number and order to the ones
-!   listed in the uzf_fill_budobj routine.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LENBUDTXT
     ! -- dummy
@@ -2892,7 +2807,6 @@ subroutine uzf_setup_budobj(this)
     real(DP) :: q
     character(len=LENBUDTXT) :: text
     character(len=LENBUDTXT), dimension(1) :: auxtxt
-! ------------------------------------------------------------------------------
     !
     ! -- Determine the number of uzf to uzf connections
     nlen = 0
@@ -3075,19 +2989,13 @@ subroutine uzf_setup_budobj(this)
       call this%budobj%flowtable_df(this%iout, cellids='GWF')
     end if
     !
-    ! -- return
+    ! -- Return
     return
-
   end subroutine uzf_setup_budobj
 
+  !> @brief Copy flow terms into this%budobj
+  !<
   subroutine uzf_fill_budobj(this)
-! ******************************************************************************
-! uzf_fill_budobj -- copy flow terms into this%budobj
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(UzfType) :: this
     ! -- local
@@ -3103,8 +3011,6 @@ subroutine uzf_fill_budobj(this)
     real(DP) :: thick
     real(DP) :: fm
     real(DP) :: v
-    ! -- formats
-! -----------------------------------------------------------------------------
     !
     ! -- initialize counter
     idx = 0
@@ -3236,7 +3142,7 @@ subroutine uzf_fill_budobj(this)
     ! --Terms are filled, now accumulate them for this time step
     call this%budobj%accumulate_terms()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzf_fill_budobj
 
diff --git a/src/Model/GroundWaterFlow/gwf3vsc8.f90 b/src/Model/GroundWaterFlow/gwf3vsc8.f90
index d803f5937ee..56af59c0424 100644
--- a/src/Model/GroundWaterFlow/gwf3vsc8.f90
+++ b/src/Model/GroundWaterFlow/gwf3vsc8.f90
@@ -64,6 +64,7 @@ module GwfVscModule
     integer(I4B), dimension(:), pointer, contiguous :: nodekchange => null() ! grid array of flags indicating for each node whether its K (or K22, or K33) value changed (1) at (kchangeper, kchangestp) or not (0)
 
   contains
+
     procedure :: vsc_df
     procedure :: vsc_ar
     procedure, public :: vsc_ar_bnd
@@ -90,16 +91,11 @@ module GwfVscModule
 
 contains
 
+  !> @brief Generic function to calculate changes in fluid viscosity using a
+  !! linear formulation
+  !<
   function calc_visc(ivisc, viscref, dviscdc, cviscref, conc, &
                      a2, a3, a4) result(visc)
-! ******************************************************************************
-! calc_visc -- generic function to calculate changes in fluid viscosity
-!                  using a linear formulation
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-
     ! -- dummy
     integer(I4B), dimension(:), intent(in) :: ivisc
     real(DP), intent(in) :: viscref
@@ -114,11 +110,10 @@ function calc_visc(ivisc, viscref, dviscdc, cviscref, conc, &
     integer(I4B) :: i
     real(DP) :: mu_t
     real(DP) :: expon
-! ------------------------------------------------------------------------------
     !
     nviscspec = size(dviscdc)
     visc = viscref
-
+    !
     do i = 1, nviscspec
       if (ivisc(i) == 1) then
         visc = visc + dviscdc(i) * (conc(i) - cviscref(i))
@@ -136,14 +131,13 @@ function calc_visc(ivisc, viscref, dviscdc, cviscref, conc, &
       ! end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end function calc_visc
 
   !> @ brief Create a new package object
   !!
   !!  Create a new VSC Package object.
-  !!
   !<
   subroutine vsc_cr(vscobj, name_model, inunit, iout)
     ! -- dummy
@@ -151,7 +145,6 @@ subroutine vsc_cr(vscobj, name_model, inunit, iout)
     character(len=*), intent(in) :: name_model
     integer(I4B), intent(in) :: inunit
     integer(I4B), intent(in) :: iout
-! ------------------------------------------------------------------------------
     !
     ! -- Create the object
     allocate (vscobj)
@@ -176,27 +169,23 @@ end subroutine vsc_cr
   !> @ brief Define viscosity package options and dimensions
   !!
   !!  Define viscosity package options and dimensions
-  !!
   !<
   subroutine vsc_df(this, dis, vsc_input)
-    ! -- modules
     ! -- dummy
     class(GwfVscType) :: this !< this viscosity package
     class(DisBaseType), pointer, intent(in) :: dis !< pointer to discretization
     type(GwfVscInputDataType), optional, intent(in) :: vsc_input !< optional vsc input data, otherwise read from file
-    ! -- local
     ! -- formats
     character(len=*), parameter :: fmtvsc = &
       "(1x,/1x,'VSC -- Viscosity Package, version 1, 11/15/2022', &
       &' input read from unit ', i0, //)"
-! ------------------------------------------------------------------------------
     !
     ! --print a message identifying the viscosity package
     write (this%iout, fmtvsc) this%inunit
     !
     ! -- store pointers to arguments that were passed in
     this%dis => dis
-
+    !
     if (.not. present(vsc_input)) then
       !
       ! -- Read viscosity options
@@ -212,7 +201,7 @@ subroutine vsc_df(this, dis, vsc_input)
     !
     ! -- Allocate arrays
     call this%allocate_arrays(dis%nodes)
-
+    !
     if (.not. present(vsc_input)) then
       !
       ! -- Read viscosity packagedata
@@ -230,16 +219,11 @@ end subroutine vsc_df
   !!
   !!  Generic method to allocate and read static data for the viscosity
   !!  package available within the GWF model type.
-  !!
   !<
   subroutine vsc_ar(this, ibound)
-    ! -- modules
     ! -- dummy
     class(GwfVscType) :: this
     integer(I4B), dimension(:), pointer :: ibound
-    ! -- local
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- store pointers to arguments that were passed in
     this%ibound => ibound
@@ -256,7 +240,6 @@ end subroutine vsc_ar
   !! Viscosity ar_bnd rountine to activate viscosity in the advanced
   !! packages.  This routine is called from gwf_ar() as it moves through each
   !! package
-  !!
   !<
   subroutine vsc_ar_bnd(this, packobj)
     ! -- modules
@@ -270,8 +253,6 @@ subroutine vsc_ar_bnd(this, packobj)
     ! -- dummy
     class(GwfVscType) :: this
     class(BndType), pointer :: packobj
-    ! -- local
-    ! ----------------------------------------------------------------------------
     !
     ! -- Add density terms based on boundary package type
     select case (packobj%filtyp)
@@ -303,7 +284,6 @@ subroutine vsc_ar_bnd(this, packobj)
       type is (LakType)
         call packobj%lak_activate_viscosity()
       end select
-
     case ('SFR')
       !
       ! -- activate viscosity for sfr package
@@ -311,7 +291,6 @@ subroutine vsc_ar_bnd(this, packobj)
       type is (SfrType)
         call packobj%sfr_activate_viscosity()
       end select
-
     case ('MAW')
       !
       ! -- activate viscosity for maw package
@@ -319,7 +298,6 @@ subroutine vsc_ar_bnd(this, packobj)
       type is (MawType)
         call packobj%maw_activate_viscosity()
       end select
-
     case default
       !
       ! -- nothing
@@ -333,12 +311,11 @@ end subroutine vsc_ar_bnd
   !!
   !! Set array and variable pointers from the NPF
   !! package for access by VSC.
-  !!
   !<
   subroutine set_npf_pointers(this)
-    ! -- dummy variables
+    ! -- dummy
     class(GwfVscType) :: this
-    ! -- local variables
+    ! -- local
     character(len=LENMEMPATH) :: npfMemoryPath
     !
     ! -- Set pointers to other package variables
@@ -354,13 +331,13 @@ subroutine set_npf_pointers(this)
     call mem_setptr(this%kchangestp, 'KCHANGESTP', npfMemoryPath)
     call mem_setptr(this%nodekchange, 'NODEKCHANGE', npfMemoryPath)
     !
+    ! -- Return
     return
   end subroutine set_npf_pointers
 
   !> @ brief Read new period data in viscosity package
   !!
   !!  Method to read and prepare period data for the VSC package.
-  !!
   !<
   subroutine vsc_rp(this)
     ! -- modules
@@ -376,7 +353,6 @@ subroutine vsc_rp(this)
        &for species ',i0,'. One or more model names may be specified &
        &incorrectly in the PACKAGEDATA block or a GWF-GWT exchange may need &
        &to be activated.')"
-! ------------------------------------------------------------------------------
     !
     ! -- Check to make sure all concentration pointers have been set
     if (kstp * kper == 1) then
@@ -391,22 +367,18 @@ subroutine vsc_rp(this)
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine vsc_rp
 
   !> @ brief Advance the viscosity package
   !!
-  !!  Advance data in the VSC package. The method sets or
-  !!  advances time series, time array series, and observation
-  !!  data.
-  !!
+  !!  Advance data in the VSC package. The method sets or advances time series,
+  !!  time array series, and observation data.
   !<
   subroutine vsc_ad(this)
     ! -- dummy
     class(GwfVscType) :: this
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- update viscosity using the latest concentration/temperature
     call this%vsc_calcvisc()
@@ -519,6 +491,9 @@ subroutine vsc_ad_standard_bnd(packobj, hnew, visc, viscref, locelev, &
                                  ivisc, a2, a3, a4, ctemp)
     ! -- modules
     use BndModule, only: BndType
+    use DrnModule, only: DrnType
+    use RivModule, only: RivType
+    use GhbModule, only: GhbType
     class(BndType), pointer :: packobj
     ! -- dummy
     real(DP), intent(in), dimension(:) :: hnew
@@ -536,7 +511,6 @@ subroutine vsc_ad_standard_bnd(packobj, hnew, visc, viscref, locelev, &
     integer(I4B) :: n
     integer(I4B) :: node
     real(DP) :: viscbnd
-! -------------------------------------------------------------------------------
     !
     ! -- Process density terms for each GHB
     do n = 1, packobj%nbound
@@ -551,8 +525,29 @@ subroutine vsc_ad_standard_bnd(packobj, hnew, visc, viscref, locelev, &
                                    packobj%auxvar)
       !
       ! -- update boundary conductance based on viscosity effects
-      packobj%bound(2, n) = update_bnd_cond(viscbnd, viscref, &
+      select case (packobj%filtyp)
+      case ('DRN')
+        select type (packobj)
+        type is (DrnType)
+          packobj%cond(n) = update_bnd_cond(viscbnd, viscref, &
+                                            packobj%condinput(n))
+        end select
+      case ('GHB')
+        select type (packobj)
+        type is (GhbType)
+          packobj%cond(n) = update_bnd_cond(viscbnd, viscref, &
+                                            packobj%condinput(n))
+        end select
+      case ('RIV')
+        select type (packobj)
+        type is (RivType)
+          packobj%cond(n) = update_bnd_cond(viscbnd, viscref, &
                                             packobj%condinput(n))
+        end select
+      case default
+        packobj%bound(2, n) = update_bnd_cond(viscbnd, viscref, &
+                                              packobj%condinput(n))
+      end select
       !
     end do
     !
@@ -586,7 +581,6 @@ subroutine vsc_ad_sfr(packobj, visc, viscref, elev, locvisc, locconc, &
     integer(I4B) :: n
     integer(I4B) :: node
     real(DP) :: viscsfr
-! -------------------------------------------------------------------------------
     !
     ! -- update viscosity ratios for updating hyd. cond (and conductance)
     select type (packobj)
@@ -644,7 +638,6 @@ subroutine vsc_ad_lak(packobj, visc, viscref, elev, locvisc, locconc, &
     integer(I4B) :: n
     integer(I4B) :: node
     real(DP) :: visclak
-! -------------------------------------------------------------------------------
     !
     ! -- update viscosity ratios for updating hyd. cond (and conductance)
     select type (packobj)
@@ -702,7 +695,6 @@ subroutine vsc_ad_maw(packobj, visc, viscref, elev, locvisc, locconc, &
     integer(I4B) :: n
     integer(I4B) :: node
     real(DP) :: viscmaw
-! -------------------------------------------------------------------------------
     !
     ! -- update viscosity ratios for updating hyd. cond (and conductance)
     select type (packobj)
@@ -740,7 +732,6 @@ end subroutine vsc_ad_maw
   !! active boundary package's conductance term.
   !<
   function update_bnd_cond(bndvisc, viscref, spcfdcond) result(updatedcond)
-    ! -- modules
     ! -- dummy
     real(DP), intent(in) :: viscref
     real(DP), intent(in) :: bndvisc
@@ -748,7 +739,6 @@ function update_bnd_cond(bndvisc, viscref, spcfdcond) result(updatedcond)
     ! -- local
     real(DP) :: vscratio
     real(DP) :: updatedcond
-! -------------------------------------------------------------------------------
     !
     vscratio = calc_vsc_ratio(viscref, bndvisc)
     !
@@ -767,7 +757,6 @@ function calc_vsc_ratio(viscref, bndvisc) result(viscratio)
     real(DP), intent(in) :: bndvisc
     ! -- local
     real(DP) :: viscratio
-! -------------------------------------------------------------------------------
     !
     viscratio = viscref / bndvisc
     !
@@ -797,11 +786,10 @@ function calc_bnd_viscosity(n, locvisc, locconc, viscref, dviscdc, cviscref, &
     real(DP), dimension(:), intent(in) :: cviscref
     real(DP), dimension(:), intent(inout) :: ctemp
     real(DP), dimension(:, :), intent(in) :: auxvar
-    ! -- return
+    ! -- Return
     real(DP) :: viscbnd
     ! -- local
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     ! -- assign boundary viscosity based on one of three options
     if (locvisc > 0) then
@@ -821,7 +809,7 @@ function calc_bnd_viscosity(n, locvisc, locconc, viscref, dviscdc, cviscref, &
       viscbnd = viscref
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end function calc_bnd_viscosity
 
@@ -842,8 +830,7 @@ subroutine get_visc_ratio(this, n, m, gwhdn, gwhdm, viscratio)
     real(DP), intent(inout) :: viscratio
     ! -- loca
     integer(I4B) :: cellid
-! ------------------------------------------------------------------------------
-!
+    !
     viscratio = DONE
     if (gwhdm > gwhdn) then
       cellid = m
@@ -852,7 +839,7 @@ subroutine get_visc_ratio(this, n, m, gwhdn, gwhdm, viscratio)
     end if
     call this%calc_q_visc(cellid, viscratio)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine get_visc_ratio
 
@@ -866,11 +853,10 @@ subroutine calc_q_visc(this, cellid, viscratio)
     ! -- dummy variables
     class(GwfVscType) :: this
     integer(I4B), intent(in) :: cellid
-    ! -- return
+    ! -- Return
     real(DP), intent(inout) :: viscratio
     ! -- local
     real(DP) :: visc
-! ------------------------------------------------------------------------------
     !
     ! -- Retrieve viscosity for the passed node number
     visc = this%visc(cellid)
@@ -878,7 +864,7 @@ subroutine calc_q_visc(this, cellid, viscratio)
     ! -- Calculate the viscosity ratio for the
     viscratio = calc_vsc_ratio(this%viscref, visc)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine calc_q_visc
 
@@ -890,13 +876,11 @@ end subroutine calc_q_visc
   !! for each cell.
   !<
   subroutine update_k_with_vsc(this)
-    ! -- modules
     ! -- dummy
     class(GwfVscType) :: this
     ! -- local
     integer(I4B) :: n
     real(DP) :: viscratio
-! ------------------------------------------------------------------------------
     !
     ! -- For viscosity-based K's, apply change of K to K11 by starting with
     !    user-specified K values and not the K's leftover from the last viscosity
@@ -912,7 +896,7 @@ subroutine update_k_with_vsc(this)
     ! -- Flag kchange
     call this%vsc_set_changed_at(kper, kstp)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine update_k_with_vsc
 
@@ -920,7 +904,6 @@ end subroutine update_k_with_vsc
   !!
   !! Procedure called by VSC code when K updated due to viscosity changes.
   !! K values changed at (kper, kstp).
-  !!
   !<
   subroutine vsc_set_changed_at(this, kper, kstp)
     ! -- dummy variables
@@ -931,13 +914,13 @@ subroutine vsc_set_changed_at(this, kper, kstp)
     this%kchangeper = kper
     this%kchangestp = kstp
     !
+    ! -- Return
     return
   end subroutine vsc_set_changed_at
 
   !> @ brief Output viscosity package dependent-variable terms.
   !!
   !!  Save calculated viscosity array to binary file
-  !!
   !<
   subroutine vsc_ot_dv(this, idvfl)
     ! -- dummy
@@ -950,7 +933,6 @@ subroutine vsc_ot_dv(this, idvfl)
     integer(I4B) :: nvaluesp
     integer(I4B) :: nwidthp
     real(DP) :: dinact
-! ------------------------------------------------------------------------------
     !
     ! -- Set unit number for viscosity output
     if (this%ioutvisc /= 0) then
@@ -969,7 +951,7 @@ subroutine vsc_ot_dv(this, idvfl)
       if (this%ioutvisc /= 0) then
         ibinun = this%ioutvisc
         call this%dis%record_array(this%visc, this%iout, iprint, ibinun, &
-                                   '         VISCOSITY', cdatafmp, nvaluesp, &
+                                   '       VISCOSITY', cdatafmp, nvaluesp, &
                                    nwidthp, editdesc, dinact)
       end if
     end if
@@ -981,13 +963,10 @@ end subroutine vsc_ot_dv
   !> @ brief Deallocate viscosity package memory
   !!
   !!  Deallocate viscosity package scalars and arrays.
-  !!
   !<
   subroutine vsc_da(this)
-    ! -- modules
     ! -- dummy
     class(GwfVscType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Deallocate arrays if package was active
     if (this%inunit > 0) then
@@ -1034,7 +1013,6 @@ end subroutine vsc_da
   !> @ brief Read dimensions
   !!
   !! Read dimensions for the viscosity package
-  !!
   !<
   subroutine read_dimensions(this)
     ! -- modules
@@ -1044,8 +1022,6 @@ subroutine read_dimensions(this)
     character(len=LINELENGTH) :: errmsg, keyword
     integer(I4B) :: ierr
     logical :: isfound, endOfBlock
-    ! -- format
-! ------------------------------------------------------------------------------
     !
     ! -- get dimensions block
     call this%parser%GetBlock('DIMENSIONS', isfound, ierr, &
@@ -1081,17 +1057,15 @@ subroutine read_dimensions(this)
       call this%parser%StoreErrorUnit()
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine read_dimensions
 
   !> @ brief Read data for package
   !!
   !!  Method to read data for the viscosity package.
-  !!
   !<
   subroutine read_packagedata(this)
-    ! -- modules
     ! -- dummy
     class(GwfVscType) :: this
     ! -- local
@@ -1109,7 +1083,6 @@ subroutine read_packagedata(this)
       "('Invalid value for IRHOSPEC (',i0,') detected in VSC Package. &
       &IRHOSPEC must be > 0 and <= NVISCSPECIES, and duplicate values &
       &are not allowed.')"
-! ------------------------------------------------------------------------------
     !
     ! -- initialize
     allocate (itemp(this%nviscspecies))
@@ -1191,41 +1164,41 @@ subroutine read_packagedata(this)
     !
     write (this%iout, '(/,1x,a)') 'End of VSC PACKAGEDATA block'
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine read_packagedata
 
   !> @brief Sets package data instead of reading from file
   !<
   subroutine set_packagedata(this, input_data)
+    ! -- dummy
     class(GwfVscType) :: this !< this vscoancy pkg
     type(GwfVscInputDataType), intent(in) :: input_data !< the input data to be set
-    ! local
+    ! -- local
     integer(I4B) :: ispec
-
+    !
     do ispec = 1, this%nviscspecies
       this%dviscdc(ispec) = input_data%dviscdc(ispec)
       this%cviscref(ispec) = input_data%cviscref(ispec)
       this%cmodelname(ispec) = input_data%cmodelname(ispec)
       this%cauxspeciesname(ispec) = input_data%cauxspeciesname(ispec)
     end do
-
+    !
+    ! -- Return
+    return
   end subroutine set_packagedata
 
   !> @brief Calculate fluid viscosity
   !!
   !! Calculates fluid viscosity based on concentration or
   !! temperature
-  !!
   !<
   subroutine vsc_calcvisc(this)
     ! -- dummy
     class(GwfVscType) :: this
-
     ! -- local
     integer(I4B) :: n
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate the viscosity using the specified concentration and/or
     !    temperature arrays
@@ -1251,21 +1224,12 @@ end subroutine vsc_calcvisc
   !!
   !! Allocate and initialize scalars for the VSC package. The base model
   !! allocate scalars method is also called.
-  !!
   !<
   subroutine allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DZERO, DTEN, DEP3
     ! -- dummy
     class(GwfVscType) :: this
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- allocate scalars in NumericalPackageType
     call this%NumericalPackageType%allocate_scalars()
@@ -1303,16 +1267,13 @@ end subroutine allocate_scalars
   !> @ brief Allocate arrays
   !!
   !! Allocate and initialize arrays for the VSC package.
-  !!
   !<
   subroutine allocate_arrays(this, nodes)
-    ! -- modules
     ! -- dummy
     class(GwfVscType) :: this
     integer(I4B), intent(in) :: nodes
     ! -- local
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate
     call mem_allocate(this%visc, nodes, 'VISC', this%memoryPath)
@@ -1348,7 +1309,6 @@ end subroutine allocate_arrays
   !> @ brief Read Options block
   !!
   !! Reads the options block inside the VSC package.
-  !!
   !<
   subroutine read_options(this)
     ! -- modules
@@ -1371,7 +1331,6 @@ subroutine read_options(this)
     character(len=*), parameter :: fmtnonlinear = &
       "(/,1x,'Viscosity will vary non-linearly with temperature &
       &change ')"
-! ------------------------------------------------------------------------------
     !
     ! -- get options block
     call this%parser%GetBlock('OPTIONS', isfound, ierr, &
@@ -1498,9 +1457,10 @@ end subroutine read_options
   !> @brief Sets options as opposed to reading them from a file
   !<
   subroutine set_options(this, input_data)
+    ! -- dummy
     class(GwfVscType) :: this
     type(GwfVscInputDataType), intent(in) :: input_data !< the input data to be set
-
+    !
     this%viscref = input_data%viscref
     !
     ! -- Return
@@ -1513,10 +1473,8 @@ end subroutine set_options
   !! and store a pointer to these in the VSC package so that
   !! viscosity can be calculated from them.  This routine is called
   !! from the gwfgwt exchange in the exg_ar() method.
-  !!
   !<
   subroutine set_concentration_pointer(this, modelname, conc, icbund, istmpr)
-    ! -- modules
     ! -- dummy
     class(GwfVscType) :: this
     character(len=LENMODELNAME), intent(in) :: modelname
@@ -1526,7 +1484,6 @@ subroutine set_concentration_pointer(this, modelname, conc, icbund, istmpr)
     ! -- local
     integer(I4B) :: i
     logical :: found
-! ------------------------------------------------------------------------------
     !
     this%iconcset = 1
     found = .false.
diff --git a/src/Model/GroundWaterFlow/gwf3wel8.f90 b/src/Model/GroundWaterFlow/gwf3wel8.f90
index f06e2774b33..9bc5281412f 100644
--- a/src/Model/GroundWaterFlow/gwf3wel8.f90
+++ b/src/Model/GroundWaterFlow/gwf3wel8.f90
@@ -15,16 +15,15 @@
 module WelModule
   ! -- modules used by WelModule methods
   use KindModule, only: DP, I4B
-  use ConstantsModule, only: DZERO, DEM1, DONE, LENFTYPE, DNODATA, MAXCHARLEN
+  use ConstantsModule, only: DZERO, DEM1, DONE, LENFTYPE, DNODATA, LINELENGTH
   use SimVariablesModule, only: errmsg
-  use SimModule, only: store_error
+  use SimModule, only: store_error, store_error_filename
   use MemoryHelperModule, only: create_mem_path
   use BndModule, only: BndType
+  use BndExtModule, only: BndExtType
   use ObsModule, only: DefaultObsIdProcessor
   use SmoothingModule, only: sQSaturation, sQSaturationDerivative
   use ObserveModule, only: ObserveType
-  use TimeSeriesLinkModule, only: TimeSeriesLinkType, &
-                                  GetTimeSeriesLinkFromList
   use BlockParserModule, only: BlockParserType
   use InputOutputModule, only: GetUnit, openfile
   use MatrixBaseModule
@@ -37,24 +36,28 @@ module WelModule
   character(len=LENFTYPE) :: ftype = 'WEL' !< package ftype
   character(len=16) :: text = '             WEL' !< package flow text string
   !
-  type, extends(BndType) :: WelType
+  type, extends(BndExtType) :: WelType
+    real(DP), dimension(:), pointer, contiguous :: q => null() !< volumetric well rate
     integer(I4B), pointer :: iflowred => null() !< flag indicating if the AUTO_FLOW_REDUCE option is active
     real(DP), pointer :: flowred => null() !< AUTO_FLOW_REDUCE variable
     integer(I4B), pointer :: ioutafrcsv => null() !< unit number for CSV output file containing wells with reduced puping rates
   contains
     procedure :: allocate_scalars => wel_allocate_scalars
-    procedure :: bnd_options => wel_options
+    procedure :: allocate_arrays => wel_allocate_arrays
+    procedure :: source_options => wel_options
+    procedure :: log_wel_options
+    procedure :: bnd_rp => wel_rp
     procedure :: bnd_cf => wel_cf
     procedure :: bnd_fc => wel_fc
     procedure :: bnd_fn => wel_fn
     procedure :: bnd_da => wel_da
     procedure :: define_listlabel
+    procedure :: bound_value => wel_bound_value
+    procedure :: q_mult
     ! -- methods for observations
     procedure, public :: bnd_obs_supported => wel_obs_supported
     procedure, public :: bnd_df_obs => wel_df_obs
     procedure, public :: bnd_bd_obs => wel_bd_obs
-    ! -- methods for time series
-    procedure, public :: bnd_rp_ts => wel_rp_ts
     ! -- afr
     procedure, private :: wel_afr_csv_init
     procedure, private :: wel_afr_csv_write
@@ -67,7 +70,8 @@ module WelModule
   !!  Create a new WEL Package object
   !!
   !<
-  subroutine wel_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
+  subroutine wel_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
+                        mempath)
     ! -- dummy variables
     class(BndType), pointer :: packobj !< pointer to default package type
     integer(I4B), intent(in) :: id !< package id
@@ -76,6 +80,7 @@ subroutine wel_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     integer(I4B), intent(in) :: iout !< unit number of model listing file
     character(len=*), intent(in) :: namemodel !< model name
     character(len=*), intent(in) :: pakname !< package name
+    character(len=*), intent(in) :: mempath !< input mempath
     ! -- local variables
     type(WelType), pointer :: welobj
     !
@@ -84,7 +89,7 @@ subroutine wel_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     packobj => welobj
     !
     ! -- create name and memory path
-    call packobj%set_names(ibcnum, namemodel, pakname, ftype)
+    call packobj%set_names(ibcnum, namemodel, pakname, ftype, mempath)
     packobj%text = text
     !
     ! -- allocate scalars
@@ -97,8 +102,6 @@ subroutine wel_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     packobj%iout = iout
     packobj%id = id
     packobj%ibcnum = ibcnum
-    packobj%ncolbnd = 1
-    packobj%iscloc = 1
     packobj%ictMemPath = create_mem_path(namemodel, 'NPF')
     !
     ! -- return
@@ -117,12 +120,13 @@ subroutine wel_da(this)
     class(WelType) :: this !< WelType object
     !
     ! -- Deallocate parent package
-    call this%BndType%bnd_da()
+    call this%BndExtType%bnd_da()
     !
     ! -- scalars
     call mem_deallocate(this%iflowred)
     call mem_deallocate(this%flowred)
     call mem_deallocate(this%ioutafrcsv)
+    call mem_deallocate(this%q, 'Q', this%memoryPath)
     !
     ! -- return
     return
@@ -140,8 +144,8 @@ subroutine wel_allocate_scalars(this)
     ! -- dummy variables
     class(WelType) :: this !< WelType object
     !
-    ! -- call standard BndType allocate scalars
-    call this%BndType%allocate_scalars()
+    ! -- call base type allocate scalars
+    call this%BndExtType%allocate_scalars()
     !
     ! -- allocate the object and assign values to object variables
     call mem_allocate(this%iflowred, 'IFLOWRED', this%memoryPath)
@@ -157,67 +161,152 @@ subroutine wel_allocate_scalars(this)
     return
   end subroutine wel_allocate_scalars
 
-  !> @ brief Read additional options for package
+  !> @ brief Allocate arrays
     !!
-    !!  Read additional options for WEL package.
+    !! Allocate and initialize arrays for the WEL package
     !!
   !<
-  subroutine wel_options(this, option, found)
+  subroutine wel_allocate_arrays(this, nodelist, auxvar)
+    ! -- modules
+    use MemoryManagerModule, only: mem_allocate, mem_setptr, mem_checkin
+    ! -- dummy
+    class(WelType) :: this
+    integer(I4B), dimension(:), pointer, contiguous, optional :: nodelist
+    real(DP), dimension(:, :), pointer, contiguous, optional :: auxvar
+    ! -- local
+    !
+    ! -- call BndExtType allocate scalars
+    call this%BndExtType%allocate_arrays(nodelist, auxvar)
+    !
+    ! -- set constant head array input context pointer
+    call mem_setptr(this%q, 'Q', this%input_mempath)
+    !
+    ! -- checkin constant head array input context pointer
+    call mem_checkin(this%q, 'Q', this%memoryPath, &
+                     'Q', this%input_mempath)
+    !
+    ! -- return
+    return
+  end subroutine wel_allocate_arrays
+
+  !> @ brief Source additional options for package
+    !!
+    !!  Source additional options for WEL package.
+    !!
+  !<
+  subroutine wel_options(this)
     ! -- modules
     use InputOutputModule, only: urword
+    use MemoryManagerExtModule, only: mem_set_value
+    use GwfWelInputModule, only: GwfWelParamFoundType
     ! -- dummy variables
     class(WelType), intent(inout) :: this !< WelType object
-    character(len=*), intent(inout) :: option !< option keyword string
-    logical, intent(inout) :: found !< boolean indicating if option found
     ! -- local variables
-    real(DP) :: r
-    character(len=MAXCHARLEN) :: fname
-    character(len=MAXCHARLEN) :: keyword
+    character(len=LINELENGTH) :: fname
+    type(GwfWelParamFoundType) :: found
     ! -- formats
     character(len=*), parameter :: fmtflowred = &
       &"(4x, 'AUTOMATIC FLOW REDUCTION OF WELLS IMPLEMENTED.')"
     character(len=*), parameter :: fmtflowredv = &
       &"(4x, 'AUTOMATIC FLOW REDUCTION FRACTION (',g15.7,').')"
     !
-    ! -- Check for 'AUTO_FLOW_REDUCE' and set this%iflowred
-    select case (option)
-    case ('AUTO_FLOW_REDUCE')
+    ! -- source base BndExtType options
+    call this%BndExtType%source_options()
+    !
+    ! -- source well options from input context
+    call mem_set_value(this%flowred, 'FLOWRED', this%input_mempath, found%flowred)
+    call mem_set_value(fname, 'AFRCSVFILE', this%input_mempath, found%afrcsvfile)
+    call mem_set_value(this%imover, 'MOVER', this%input_mempath, found%mover)
+    !
+    if (found%flowred) then
+      !
       this%iflowred = 1
-      r = this%parser%GetDouble()
-      if (r <= DZERO) then
-        r = DEM1
-      else if (r > DONE) then
-        r = DONE
-      end if
-      this%flowred = r
       !
-      ! -- Write option and return with found set to true
+      if (this%flowred <= DZERO) then
+        this%flowred = DEM1
+      else if (this%flowred > DONE) then
+        this%flowred = DONE
+      end if
+    end if
+    !
+    if (found%afrcsvfile) then
+      call this%wel_afr_csv_init(fname)
+    end if
+    !
+    if (found%mover) then
+      this%imover = 1
+    end if
+    !
+    ! -- log WEL specific options
+    call this%log_wel_options(found)
+    !
+    ! -- return
+    return
+  end subroutine wel_options
+
+  !> @ brief Log WEL specific package options
+  !<
+  subroutine log_wel_options(this, found)
+    ! -- modules
+    use GwfWelInputModule, only: GwfWelParamFoundType
+    ! -- dummy variables
+    class(WelType), intent(inout) :: this !< BndExtType object
+    type(GwfWelParamFoundType), intent(in) :: found
+    ! -- local variables
+    ! -- format
+    character(len=*), parameter :: fmtflowred = &
+      &"(4x, 'AUTOMATIC FLOW REDUCTION OF WELLS IMPLEMENTED.')"
+    character(len=*), parameter :: fmtflowredv = &
+      &"(4x, 'AUTOMATIC FLOW REDUCTION FRACTION (',g15.7,').')"
+    !
+    ! -- log found options
+    write (this%iout, '(/1x,a)') 'PROCESSING '//trim(adjustl(this%text)) &
+      //' OPTIONS'
+    !
+    if (found%flowred) then
       if (this%iflowred > 0) &
         write (this%iout, fmtflowred)
       write (this%iout, fmtflowredv) this%flowred
-      found = .true.
-    case ('AUTO_FLOW_REDUCE_CSV')
-      call this%parser%GetStringCaps(keyword)
-      if (keyword == 'FILEOUT') then
-        call this%parser%GetString(fname)
-        call this%wel_afr_csv_init(fname)
-      else
-        call store_error('OPTIONAL AUTO_FLOW_REDUCE_CSV KEYWORD MUST BE &
-          &FOLLOWED BY FILEOUT')
-      end if
-    case ('MOVER')
-      this%imover = 1
+    end if
+    !
+    if (found%afrcsvfile) then
+      ! -- currently no-op
+    end if
+    !
+    if (found%mover) then
       write (this%iout, '(4x,A)') 'MOVER OPTION ENABLED'
-      found = .true.
-    case default
-      !
-      ! -- No options found
-      found = .false.
-    end select
+    end if
+    !
+    ! -- close logging block
+    write (this%iout, '(1x,a)') &
+      'END OF '//trim(adjustl(this%text))//' OPTIONS'
     !
     ! -- return
     return
-  end subroutine wel_options
+  end subroutine log_wel_options
+
+  !> @ brief WEL read and prepare
+    !!
+  !<
+  subroutine wel_rp(this)
+    use TdisModule, only: kper
+    ! -- dummy
+    class(WelType), intent(inout) :: this
+    ! -- local
+    !
+    if (this%iper /= kper) return
+    !
+    ! -- Call the parent class read and prepare
+    call this%BndExtType%bnd_rp()
+    !
+    ! -- Write the list to iout if requested
+    if (this%iprpak /= 0) then
+      call this%write_list()
+    end if
+    !
+    ! -- return
+    return
+  end subroutine wel_rp
 
   !> @ brief Formulate the package hcof and rhs terms.
     !!
@@ -225,10 +314,9 @@ end subroutine wel_options
     !!  added to the coefficient matrix and right-hand side vector.
     !!
   !<
-  subroutine wel_cf(this, reset_mover)
+  subroutine wel_cf(this)
     ! -- dummy variables
     class(WelType) :: this !< WelType object
-    logical, intent(in), optional :: reset_mover !< boolean for resetting mover
     ! -- local variables
     integer(I4B) :: i, node, ict
     real(DP) :: qmult
@@ -236,18 +324,10 @@ subroutine wel_cf(this, reset_mover)
     real(DP) :: tp
     real(DP) :: bt
     real(DP) :: thick
-    logical :: lrm
     !
     ! -- Return if no wells
     if (this%nbound == 0) return
     !
-    ! -- pakmvrobj cf
-    lrm = .true.
-    if (present(reset_mover)) lrm = reset_mover
-    if (this%imover == 1 .and. lrm) then
-      call this%pakmvrobj%cf()
-    end if
-    !
     ! -- Calculate hcof and rhs for each well entry
     do i = 1, this%nbound
       node = this%nodelist(i)
@@ -256,7 +336,7 @@ subroutine wel_cf(this, reset_mover)
         this%rhs(i) = DZERO
         cycle
       end if
-      q = this%bound(1, i)
+      q = this%q_mult(i)
       if (this%iflowred /= 0 .and. q < DZERO) then
         ict = this%icelltype(node)
         if (ict /= 0) then
@@ -360,7 +440,7 @@ subroutine wel_fn(this, rhs, ia, idxglo, matrix_sln)
           thick = tp - bt
           tp = bt + this%flowred * thick
           drterm = sQSaturationDerivative(tp, bt, this%xnew(node))
-          drterm = drterm * this%bound(1, i)
+          drterm = drterm * this%q_mult(i)
           !--fill amat and rhs with newton-raphson terms
           call matrix_sln%add_value_pos(idxglo(ipos), drterm)
           rhs(node) = rhs(node) + drterm * this%xnew(node)
@@ -412,11 +492,11 @@ subroutine wel_afr_csv_write(this)
       if (this%ibound(nodereduced) <= 0) then
         cycle
       end if
-      v = this%bound(1, i) + this%rhs(i)
+      v = this%q_mult(i) + this%rhs(i)
       if (v < DZERO) then
         nodeuser = this%dis%get_nodeuser(nodereduced)
         write (this%ioutafrcsv, '(*(G0,:,","))') &
-          totim, kper, kstp, i, nodeuser, this%bound(1, i), this%simvals(i), v
+          totim, kper, kstp, i, nodeuser, this%q_mult(i), this%simvals(i), v
       end if
     end do
   end subroutine wel_afr_csv_write
@@ -539,7 +619,7 @@ subroutine wel_bd_obs(this)
             v = this%simvals(jj)
           case ('WEL-REDUCTION')
             if (this%iflowred > 0) then
-              v = this%bound(1, jj) + this%rhs(jj)
+              v = this%q_mult(jj) + this%rhs(jj)
             end if
           case default
             errmsg = 'Unrecognized observation type: '//trim(obsrv%ObsTypeId)
@@ -561,34 +641,53 @@ subroutine wel_bd_obs(this)
     return
   end subroutine wel_bd_obs
 
-  ! -- Procedure related to time series
+  function q_mult(this, row) result(q)
+    ! -- modules
+    use ConstantsModule, only: DZERO
+    ! -- dummy variables
+    class(WelType), intent(inout) :: this !< BndExtType object
+    integer(I4B), intent(in) :: row
+    ! -- result
+    real(DP) :: q
+    !
+    if (this%iauxmultcol > 0) then
+      q = this%q(row) * this%auxvar(this%iauxmultcol, row)
+    else
+      q = this%q(row)
+    end if
+    !
+    ! -- return
+    return
+  end function q_mult
 
-  !> @brief Assign time series links for the package
+  !> @ brief Return a bound value
     !!
-    !! Assign the time series links for the WEL package. Only
-    !! the Q variable can be defined with time series.
+    !!  Return a bound value associated with an ncolbnd index
+    !!  and row.
     !!
   !<
-  subroutine wel_rp_ts(this)
+  function wel_bound_value(this, col, row) result(bndval)
+    ! -- modules
+    use ConstantsModule, only: DZERO
     ! -- dummy variables
-    class(WelType), intent(inout) :: this !< WelType object
-    ! -- local variables
-    integer(I4B) :: i, nlinks
-    type(TimeSeriesLinkType), pointer :: tslink => null()
-    !
-    ! -- set up the time series links
-    nlinks = this%TsManager%boundtslinks%Count()
-    do i = 1, nlinks
-      tslink => GetTimeSeriesLinkFromList(this%TsManager%boundtslinks, i)
-      if (associated(tslink)) then
-        if (tslink%JCol == 1) then
-          tslink%Text = 'Q'
-        end if
-      end if
-    end do
+    class(WelType), intent(inout) :: this !< BndExtType object
+    integer(I4B), intent(in) :: col
+    integer(I4B), intent(in) :: row
+    ! -- result
+    real(DP) :: bndval
+    !
+    select case (col)
+    case (1)
+      bndval = this%q_mult(row)
+    case default
+      errmsg = 'Programming error. WEL bound value requested column '&
+               &'outside range of ncolbnd (1).'
+      call store_error(errmsg)
+      call store_error_filename(this%input_fname)
+    end select
     !
     ! -- return
     return
-  end subroutine wel_rp_ts
+  end function wel_bound_value
 
 end module WelModule
diff --git a/src/Model/GroundWaterFlow/gwf3wel8idm.f90 b/src/Model/GroundWaterFlow/gwf3wel8idm.f90
new file mode 100644
index 00000000000..5b3b6b68d2f
--- /dev/null
+++ b/src/Model/GroundWaterFlow/gwf3wel8idm.f90
@@ -0,0 +1,525 @@
+! ** Do Not Modify! MODFLOW 6 system generated file. **
+module GwfWelInputModule
+  use ConstantsModule, only: LENVARNAME
+  use InputDefinitionModule, only: InputParamDefinitionType, &
+                                   InputBlockDefinitionType
+  private
+  public gwf_wel_param_definitions
+  public gwf_wel_aggregate_definitions
+  public gwf_wel_block_definitions
+  public GwfWelParamFoundType
+  public gwf_wel_multi_package
+
+  type GwfWelParamFoundType
+    logical :: auxiliary = .false.
+    logical :: auxmultname = .false.
+    logical :: boundnames = .false.
+    logical :: iprpak = .false.
+    logical :: iprflow = .false.
+    logical :: ipakcb = .false.
+    logical :: flowred = .false.
+    logical :: afrcsv_rec = .false.
+    logical :: afrcsv = .false.
+    logical :: fileout = .false.
+    logical :: afrcsvfile = .false.
+    logical :: ts_filerecord = .false.
+    logical :: ts6 = .false.
+    logical :: filein = .false.
+    logical :: ts6_filename = .false.
+    logical :: obs_filerecord = .false.
+    logical :: obs6 = .false.
+    logical :: obs6_filename = .false.
+    logical :: mover = .false.
+    logical :: maxbound = .false.
+    logical :: cellid = .false.
+    logical :: q = .false.
+    logical :: auxvar = .false.
+    logical :: boundname = .false.
+  end type GwfWelParamFoundType
+
+  logical :: gwf_wel_multi_package = .true.
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_auxiliary = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXILIARY', & ! tag name
+    'AUXILIARY', & ! fortran variable
+    'STRING', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_auxmultname = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXMULTNAME', & ! tag name
+    'AUXMULTNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_boundnames = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'BOUNDNAMES', & ! tag name
+    'BOUNDNAMES', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_iprpak = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_INPUT', & ! tag name
+    'IPRPAK', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_iprflow = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_FLOWS', & ! tag name
+    'IPRFLOW', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_ipakcb = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'SAVE_FLOWS', & ! tag name
+    'IPAKCB', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_flowred = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUTO_FLOW_REDUCE', & ! tag name
+    'FLOWRED', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_afrcsv_rec = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'AFRCSV_FILERECORD', & ! tag name
+    'AFRCSV_REC', & ! fortran variable
+    'RECORD AUTO_FLOW_REDUCE_CSV FILEOUT AFRCSVFILE', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_afrcsv = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUTO_FLOW_REDUCE_CSV', & ! tag name
+    'AFRCSV', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_fileout = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'FILEOUT', & ! tag name
+    'FILEOUT', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_afrcsvfile = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'AFRCSVFILE', & ! tag name
+    'AFRCSVFILE', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_ts_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS_FILERECORD', & ! tag name
+    'TS_FILERECORD', & ! fortran variable
+    'RECORD TS6 FILEIN TS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_ts6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS6', & ! tag name
+    'TS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_filein = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'FILEIN', & ! tag name
+    'FILEIN', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_ts6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS6_FILENAME', & ! tag name
+    'TS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_obs_filerecord = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS_FILERECORD', & ! tag name
+    'OBS_FILERECORD', & ! fortran variable
+    'RECORD OBS6 FILEIN OBS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_obs6 = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6', & ! tag name
+    'OBS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_obs6_filename = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6_FILENAME', & ! tag name
+    'OBS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_mover = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'OPTIONS', & ! block
+    'MOVER', & ! tag name
+    'MOVER', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_maxbound = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'DIMENSIONS', & ! block
+    'MAXBOUND', & ! tag name
+    'MAXBOUND', & ! fortran variable
+    'INTEGER', & ! type
+    '', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_cellid = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'PERIOD', & ! block
+    'CELLID', & ! tag name
+    'CELLID', & ! fortran variable
+    'INTEGER1D', & ! type
+    'NCELLDIM', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_q = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'PERIOD', & ! block
+    'Q', & ! tag name
+    'Q', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_auxvar = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'PERIOD', & ! block
+    'AUX', & ! tag name
+    'AUXVAR', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_boundname = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'PERIOD', & ! block
+    'BOUNDNAME', & ! tag name
+    'BOUNDNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_wel_param_definitions(*) = &
+    [ &
+    gwfwel_auxiliary, &
+    gwfwel_auxmultname, &
+    gwfwel_boundnames, &
+    gwfwel_iprpak, &
+    gwfwel_iprflow, &
+    gwfwel_ipakcb, &
+    gwfwel_flowred, &
+    gwfwel_afrcsv_rec, &
+    gwfwel_afrcsv, &
+    gwfwel_fileout, &
+    gwfwel_afrcsvfile, &
+    gwfwel_ts_filerecord, &
+    gwfwel_ts6, &
+    gwfwel_filein, &
+    gwfwel_ts6_filename, &
+    gwfwel_obs_filerecord, &
+    gwfwel_obs6, &
+    gwfwel_obs6_filename, &
+    gwfwel_mover, &
+    gwfwel_maxbound, &
+    gwfwel_cellid, &
+    gwfwel_q, &
+    gwfwel_auxvar, &
+    gwfwel_boundname &
+    ]
+
+  type(InputParamDefinitionType), parameter :: &
+    gwfwel_spd = InputParamDefinitionType &
+    ( &
+    'GWF', & ! component
+    'WEL', & ! subcomponent
+    'PERIOD', & ! block
+    'STRESS_PERIOD_DATA', & ! tag name
+    'SPD', & ! fortran variable
+    'RECARRAY CELLID Q AUX BOUNDNAME', & ! type
+    'MAXBOUND', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwf_wel_aggregate_definitions(*) = &
+    [ &
+    gwfwel_spd &
+    ]
+
+  type(InputBlockDefinitionType), parameter :: &
+    gwf_wel_block_definitions(*) = &
+    [ &
+    InputBlockDefinitionType( &
+    'OPTIONS', & ! blockname
+    .false., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'DIMENSIONS', & ! blockname
+    .true., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'PERIOD', & ! blockname
+    .true., & ! required
+    .true., & ! aggregate
+    .true. & ! block_variable
+    ) &
+    ]
+
+end module GwfWelInputModule
diff --git a/src/Model/GroundWaterTransport/gwt1.f90 b/src/Model/GroundWaterTransport/gwt1.f90
index 0e391664630..8f32e270e72 100644
--- a/src/Model/GroundWaterTransport/gwt1.f90
+++ b/src/Model/GroundWaterTransport/gwt1.f90
@@ -8,22 +8,17 @@
 module GwtModule
 
   use KindModule, only: DP, I4B
-  use ConstantsModule, only: LENFTYPE, LENMEMPATH, DZERO, LENPAKLOC
+  use ConstantsModule, only: LENFTYPE, LENMEMPATH, DZERO, DONE, &
+                             LENPAKLOC, LENVARNAME, LENPACKAGETYPE
   use VersionModule, only: write_listfile_header
   use NumericalModelModule, only: NumericalModelType
-  use TransportModelModule, only: TransportModelType
+
   use BaseModelModule, only: BaseModelType
   use BndModule, only: BndType, AddBndToList, GetBndFromList
-  use GwtIcModule, only: GwtIcType
-  use GwtFmiModule, only: GwtFmiType
-  use GwtAdvModule, only: GwtAdvType
   use GwtDspModule, only: GwtDspType
-  use GwtSsmModule, only: GwtSsmType
-  use GwtMvtModule, only: GwtMvtType
   use GwtMstModule, only: GwtMstType
-  use GwtOcModule, only: GwtOcType
-  use GwtObsModule, only: GwtObsType
   use BudgetModule, only: BudgetType
+  use TransportModelModule
   use MatrixBaseModule
 
   implicit none
@@ -32,28 +27,18 @@ module GwtModule
   public :: gwt_cr
   public :: GwtModelType
   public :: CastAsGwtModel
+  public :: GWT_NBASEPKG, GWT_NMULTIPKG
+  public :: GWT_BASEPKG, GWT_MULTIPKG
+  character(len=LENVARNAME), parameter :: dvt = 'CONCENTRATION   ' !< dependent variable type, varies based on model type
+  character(len=LENVARNAME), parameter :: dvu = 'MASS            ' !< dependent variable unit of measure, either "mass" or "energy"
+  character(len=LENVARNAME), parameter :: dvua = 'M               ' !< abbreviation of the dependent variable unit of measure, either "M" or "E"
 
   type, extends(TransportModelType) :: GwtModelType
 
-    type(GwtIcType), pointer :: ic => null() ! initial conditions package
-    type(GwtFmiType), pointer :: fmi => null() ! flow model interface
     type(GwtMstType), pointer :: mst => null() ! mass storage and transfer package
-    type(GwtAdvType), pointer :: adv => null() ! advection package
     type(GwtDspType), pointer :: dsp => null() ! dispersion package
-    type(GwtSsmType), pointer :: ssm => null() ! source sink mixing package
-    type(GwtMvtType), pointer :: mvt => null() ! mover transport package
-    type(GwtOcType), pointer :: oc => null() ! output control package
-    type(GwtObsType), pointer :: obs => null() ! observation package
-    type(BudgetType), pointer :: budget => null() ! budget object
-    integer(I4B), pointer :: inic => null() ! unit number IC
-    integer(I4B), pointer :: infmi => null() ! unit number FMI
-    integer(I4B), pointer :: inmvt => null() ! unit number MVT
     integer(I4B), pointer :: inmst => null() ! unit number MST
-    integer(I4B), pointer :: inadv => null() ! unit number ADV
     integer(I4B), pointer :: indsp => null() ! DSP enabled flag
-    integer(I4B), pointer :: inssm => null() ! unit number SSM
-    integer(I4B), pointer :: inoc => null() ! unit number OC
-    integer(I4B), pointer :: inobs => null() ! unit number OBS
 
   contains
 
@@ -71,130 +56,122 @@ module GwtModule
     procedure :: model_ot => gwt_ot
     procedure :: model_da => gwt_da
     procedure :: model_bdentry => gwt_bdentry
-
     procedure :: allocate_scalars
-    procedure, private :: package_create
-    procedure, private :: ftype_check
     procedure :: get_iasym => gwt_get_iasym
-    procedure, private :: gwt_ot_flow
-    procedure, private :: gwt_ot_flowja
-    procedure, private :: gwt_ot_dv
-    procedure, private :: gwt_ot_bdsummary
-    procedure, private :: gwt_ot_obs
-    procedure, private :: create_packages
+    procedure :: create_packages => create_gwt_packages
     procedure, private :: create_bndpkgs
-    procedure, private :: create_lstfile
-    procedure, private :: log_namfile_options
+    procedure, private :: package_create
+
   end type GwtModelType
 
+  !> @brief GWT base package array descriptors
+  !!
+  !! GWT6 model base package types.  Only listed packages are candidates
+  !! for input and these will be loaded in the order specified.
+  !<
+  integer(I4B), parameter :: GWT_NBASEPKG = 50
+  character(len=LENPACKAGETYPE), dimension(GWT_NBASEPKG) :: GWT_BASEPKG
+  data GWT_BASEPKG/'DIS6 ', 'DISV6', 'DISU6', '     ', '     ', & !  5
+                  &'IC6  ', 'FMI6 ', 'MST6 ', 'ADV6 ', '     ', & ! 10
+                  &'DSP6 ', 'SSM6 ', 'MVT6 ', 'OC6  ', '     ', & ! 15
+                  &'OBS6 ', '     ', '     ', '     ', '     ', & ! 20
+                  &30*'     '/ ! 50
+
+  !> @brief GWT multi package array descriptors
+  !!
+  !! GWT6 model multi-instance package types.  Only listed packages are
+  !! candidates for input and these will be loaded in the order specified.
+  !<
+  integer(I4B), parameter :: GWT_NMULTIPKG = 50
+  character(len=LENPACKAGETYPE), dimension(GWT_NMULTIPKG) :: GWT_MULTIPKG
+  data GWT_MULTIPKG/'CNC6 ', 'SRC6 ', 'LKT6 ', 'IST6 ', '     ', & !  5
+                   &'SFT6 ', 'MWT6 ', 'UZT6 ', 'API6 ', '     ', & ! 10
+                   &40*'     '/ ! 50
+
+  ! -- size of supported model package arrays
+  integer(I4B), parameter :: NIUNIT_GWT = GWT_NBASEPKG + GWT_NMULTIPKG
+
 contains
 
+  !> @brief Create a new groundwater transport model object
+  !<
   subroutine gwt_cr(filename, id, modelname)
-! ******************************************************************************
-! gwt_cr -- Create a new groundwater transport model object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ListsModule, only: basemodellist
     use BaseModelModule, only: AddBaseModelToList
-    use ConstantsModule, only: LINELENGTH
+    use ConstantsModule, only: LINELENGTH, LENPACKAGENAME
     use MemoryHelperModule, only: create_mem_path
     use MemoryManagerExtModule, only: mem_set_value
-    use SimVariablesModule, only: idm_context
-    use GwfNamInputModule, only: GwfNamParamFoundType
+    use GwtNamInputModule, only: GwtNamParamFoundType
     use BudgetModule, only: budget_cr
     ! -- dummy
     character(len=*), intent(in) :: filename
     integer(I4B), intent(in) :: id
     character(len=*), intent(in) :: modelname
     ! -- local
+    integer(I4B) :: indis
     type(GwtModelType), pointer :: this
     class(BaseModelType), pointer :: model
-    character(len=LENMEMPATH) :: input_mempath
-    character(len=LINELENGTH) :: lst_fname
-    type(GwfNamParamFoundType) :: found
-    ! -- format
-! ------------------------------------------------------------------------------
     !
-    ! -- Allocate a new GWT Model (this) and add it to basemodellist
+    ! -- Allocate a new GWT Model (this)
     allocate (this)
     !
     ! -- Set memory path before allocation in memory manager can be done
     this%memoryPath = create_mem_path(modelname)
     !
+    ! -- Allocate scalars and add model to basemodellist
     call this%allocate_scalars(modelname)
-    model => this
-    call AddBaseModelToList(basemodellist, model)
     !
-    ! -- Assign values
-    this%filename = filename
-    this%name = modelname
-    this%macronym = 'GWT'
-    this%id = id
-    !
-    ! -- set input model namfile memory path
-    input_mempath = create_mem_path(modelname, 'NAM', idm_context)
-    !
-    ! -- copy option params from input context
-    call mem_set_value(lst_fname, 'LIST', input_mempath, found%list)
-    call mem_set_value(this%iprpak, 'PRINT_INPUT', input_mempath, &
-                       found%print_input)
-    call mem_set_value(this%iprflow, 'PRINT_FLOWS', input_mempath, &
-                       found%print_flows)
-    call mem_set_value(this%ipakcb, 'SAVE_FLOWS', input_mempath, found%save_flows)
-    !
-    ! -- create the list file
-    call this%create_lstfile(lst_fname, filename, found%list)
-    !
-    ! -- activate save_flows if found
-    if (found%save_flows) then
-      this%ipakcb = -1
-    end if
+    ! -- set labels for transport model - needed by create_packages() below
+    call this%set_tsp_labels(this%macronym, dvt, dvu, dvua)
     !
-    ! -- log set options
-    if (this%iout > 0) then
-      call this%log_namfile_options(found)
-    end if
+    model => this
+    call AddBaseModelToList(basemodellist, model)
     !
-    ! -- Create utility objects
-    call budget_cr(this%budget, this%name)
+    ! -- Call parent class routine
+    call this%tsp_cr(filename, id, modelname, 'GWT', indis)
     !
     ! -- create model packages
-    call this%create_packages()
+    call this%create_packages(indis)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwt_cr
 
+  !> @brief Define packages of the GWT model
+  !!
+  !! This subroutine defines a gwt model type. Steps include:
+  !!  (1) call df routines for each package
+  !!  (2) set variables and pointers
+  !<
   subroutine gwt_df(this)
-! ******************************************************************************
-! gwt_df -- Define packages of the model
-! Subroutine: (1) call df routines for each package
-!             (2) set variables and pointers
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
-    use ModelPackageInputsModule, only: NIUNIT_GWT
+    use SimModule, only: store_error
     ! -- dummy
     class(GwtModelType) :: this
     ! -- local
     integer(I4B) :: ip
     class(BndType), pointer :: packobj
-! ------------------------------------------------------------------------------
     !
     ! -- Define packages and utility objects
     call this%dis%dis_df()
-    call this%fmi%fmi_df(this%dis, this%inssm)
+    call this%fmi%fmi_df(this%dis)
     if (this%inmvt > 0) call this%mvt%mvt_df(this%dis)
     if (this%inadv > 0) call this%adv%adv_df()
     if (this%indsp > 0) call this%dsp%dsp_df(this%dis)
     if (this%inssm > 0) call this%ssm%ssm_df()
     call this%oc%oc_df()
-    call this%budget%budget_df(NIUNIT_GWT, 'MASS', 'M')
+    call this%budget%budget_df(NIUNIT_GWT, this%depvarunit, &
+                               this%depvarunitabbrev)
+    !
+    ! -- Check for SSM package
+    if (this%inssm == 0) then
+      if (this%fmi%nflowpack > 0) then
+        call store_error('Flow model has boundary packages, but there &
+          &is no SSM package.  The SSM package must be activated.', &
+          terminate=.TRUE.)
+      end if
+    end if
     !
     ! -- Assign or point model members to dis members
     this%neq = this%dis%nodes
@@ -216,17 +193,13 @@ subroutine gwt_df(this)
     ! -- Store information needed for observations
     call this%obs%obs_df(this%iout, this%name, 'GWT', this%dis)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwt_df
 
+  !> @brief Add the internal connections of this model to the sparse matrix
+  !<
   subroutine gwt_ac(this, sparse)
-! ******************************************************************************
-! gwt_ac -- Add the internal connections of this model to the sparse matrix
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SparseModule, only: sparsematrix
     ! -- dummy
@@ -235,7 +208,6 @@ subroutine gwt_ac(this, sparse)
     ! -- local
     class(BndType), pointer :: packobj
     integer(I4B) :: ip
-! ------------------------------------------------------------------------------
     !
     ! -- Add the internal connections of this model to sparse
     call this%dis%dis_ac(this%moffset, sparse)
@@ -248,29 +220,25 @@ subroutine gwt_ac(this, sparse)
       call packobj%bnd_ac(this%moffset, sparse)
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwt_ac
 
+  !> @brief Map the positions of the GWT model connections in the numerical
+  !! solution coefficient matrix.
+  !<
   subroutine gwt_mc(this, matrix_sln)
-! ******************************************************************************
-! gwt_mc -- Map the positions of this models connections in the
-! numerical solution coefficient matrix.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtModelType) :: this
     class(MatrixBaseType), pointer :: matrix_sln !< global system matrix
     ! -- local
     class(BndType), pointer :: packobj
     integer(I4B) :: ip
-! ------------------------------------------------------------------------------
     !
     ! -- Find the position of each connection in the global ia, ja structure
     !    and store them in idxglo.
     call this%dis%dis_mc(this%moffset, this%idxglo, matrix_sln)
+    !
     if (this%indsp > 0) call this%dsp%dsp_mc(this%moffset, matrix_sln)
     !
     ! -- Map any package connections
@@ -279,19 +247,17 @@ subroutine gwt_mc(this, matrix_sln)
       call packobj%bnd_mc(this%moffset, matrix_sln)
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwt_mc
 
+  !> @brief GWT Model Allocate and Read
+  !!
+  !! This subroutine:
+  !!   - allocates and reads packages that are part of this model,
+  !!   - allocates memory for arrays used by this model object
+  !<
   subroutine gwt_ar(this)
-! ******************************************************************************
-! gwt_ar -- GroundWater Transport Model Allocate and Read
-! Subroutine: (1) allocates and reads packages part of this model,
-!             (2) allocates memory for arrays part of this model object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DHNOFLO
     ! -- dummy
@@ -299,7 +265,6 @@ subroutine gwt_ar(this)
     ! -- locals
     integer(I4B) :: ip
     class(BndType), pointer :: packobj
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate and read modules attached to model
     call this%fmi%fmi_ar(this%ibound)
@@ -309,13 +274,22 @@ subroutine gwt_ar(this)
     if (this%inadv > 0) call this%adv%adv_ar(this%dis, this%ibound)
     if (this%indsp > 0) call this%dsp%dsp_ar(this%ibound, this%mst%thetam)
     if (this%inssm > 0) call this%ssm%ssm_ar(this%dis, this%ibound, this%x)
-    if (this%inobs > 0) call this%obs%gwt_obs_ar(this%ic, this%x, this%flowja)
+    if (this%inobs > 0) call this%obs%tsp_obs_ar(this%ic, this%x, this%flowja)
+    !
+    ! -- Set governing equation scale factor. Note that this scale factor
+    ! -- cannot be set arbitrarily. For solute transport, it must be set
+    ! -- to 1.  Setting it to a different value will NOT automatically
+    ! -- scale all the terms of the governing equation correctly by that
+    ! -- value. This is because much of the coding in the associated
+    ! -- packages implicitly assumes the governing equation for solute
+    ! -- transport is scaled by 1. (effectively unscaled).
+    this%eqnsclfac = DONE
     !
     ! -- Call dis_ar to write binary grid file
     !call this%dis%dis_ar(this%npf%icelltype)
     !
     ! -- set up output control
-    call this%oc%oc_ar(this%x, this%dis, DHNOFLO)
+    call this%oc%oc_ar(this%x, this%dis, DHNOFLO, this%depvartype)
     call this%budget%set_ibudcsv(this%oc%ibudcsv)
     !
     ! -- Package input files now open, so allocate and read
@@ -327,18 +301,15 @@ subroutine gwt_ar(this)
       call packobj%bnd_ar()
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwt_ar
 
+  !> @brief GWT Model Read and Prepare
+  !!
+  !! Call the read and prepare routines of the attached packages
+  !<
   subroutine gwt_rp(this)
-! ******************************************************************************
-! gwt_rp -- GroundWater Transport Model Read and Prepare
-! Subroutine: (1) calls package read and prepare routines
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: readnewdata
     ! -- dummy
@@ -346,7 +317,6 @@ subroutine gwt_rp(this)
     ! -- local
     class(BndType), pointer :: packobj
     integer(I4B) :: ip
-! ------------------------------------------------------------------------------
     !
     ! -- In fmi, check for mvt and mvrbudobj consistency
     call this%fmi%fmi_rp(this%inmvt)
@@ -368,14 +338,11 @@ subroutine gwt_rp(this)
     return
   end subroutine gwt_rp
 
+  !> @brief GWT Model Time Step Advance
+  !!
+  !! Call the advance subroutines of the attached packages
+  !<
   subroutine gwt_ad(this)
-! ******************************************************************************
-! gwt_ad -- GroundWater Transport Model Time Step Advance
-! Subroutine: (1) calls package advance subroutines
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SimVariablesModule, only: isimcheck, iFailedStepRetry
     ! -- dummy
@@ -384,7 +351,6 @@ subroutine gwt_ad(this)
     ! -- local
     integer(I4B) :: irestore
     integer(I4B) :: ip, n
-! ------------------------------------------------------------------------------
     !
     ! -- Reset state variable
     irestore = 0
@@ -425,17 +391,15 @@ subroutine gwt_ad(this)
     ! -- Push simulated values to preceding time/subtime step
     call this%obs%obs_ad()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwt_ad
 
+  !> @brief GWT Model calculate coefficients
+  !!
+  !! Call the calculate coefficients subroutines of the attached packages
+  !<
   subroutine gwt_cf(this, kiter)
-! ******************************************************************************
-! gwt_cf -- GroundWater Transport Model calculate coefficients
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtModelType) :: this
@@ -443,7 +407,6 @@ subroutine gwt_cf(this, kiter)
     ! -- local
     class(BndType), pointer :: packobj
     integer(I4B) :: ip
-! ------------------------------------------------------------------------------
     !
     ! -- Call package cf routines
     do ip = 1, this%bndlist%Count()
@@ -451,17 +414,15 @@ subroutine gwt_cf(this, kiter)
       call packobj%bnd_cf()
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwt_cf
 
+  !> @brief GWT Model fill coefficients
+  !!
+  !! Call the fill coefficients subroutines attached packages
+  !<
   subroutine gwt_fc(this, kiter, matrix_sln, inwtflag)
-! ******************************************************************************
-! gwt_fc -- GroundWater Transport Model fill coefficients
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtModelType) :: this
@@ -471,7 +432,6 @@ subroutine gwt_fc(this, kiter, matrix_sln, inwtflag)
     ! -- local
     class(BndType), pointer :: packobj
     integer(I4B) :: ip
-! ------------------------------------------------------------------------------
     !
     ! -- call fc routines
     call this%fmi%fmi_fc(this%dis%nodes, this%xold, this%nja, matrix_sln, &
@@ -501,18 +461,20 @@ subroutine gwt_fc(this, kiter, matrix_sln, inwtflag)
       call packobj%bnd_fc(this%rhs, this%ia, this%idxglo, matrix_sln)
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwt_fc
 
+  !> @brief GWT Model Final Convergence Check
+  !!
+  !! If MVR/MVT is active, call the MVR convergence check subroutines to force
+  !! at least 2 outer iterations. The other advanced transport packages are
+  !! solved in the matrix equations directly which means the solver is
+  !! completing the necessary checks thereby eliminating need to call package
+  !! cc routines.  That is, no need to loop over active packages and run:
+  !! call packobj%bnd_cc(iend, icnvg, hclose, rclose)
+  !<
   subroutine gwt_cc(this, innertot, kiter, iend, icnvgmod, cpak, ipak, dpak)
-! ******************************************************************************
-! gwt_cc -- GroundWater Transport Model Final Convergence Check
-! Subroutine: (1) calls package cc routines
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtModelType) :: this
     integer(I4B), intent(in) :: innertot
@@ -523,32 +485,20 @@ subroutine gwt_cc(this, innertot, kiter, iend, icnvgmod, cpak, ipak, dpak)
     integer(I4B), intent(inout) :: ipak
     real(DP), intent(inout) :: dpak
     ! -- local
-    !class(BndType), pointer :: packobj
-    !integer(I4B) :: ip
     ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- If mover is on, then at least 2 outers required
     if (this%inmvt > 0) call this%mvt%mvt_cc(kiter, iend, icnvgmod, cpak, dpak)
     !
-    ! -- Call package cc routines
-    !do ip = 1, this%bndlist%Count()
-    !  packobj => GetBndFromList(this%bndlist, ip)
-    !  call packobj%bnd_cc(iend, icnvg, hclose, rclose)
-    !enddo
-    !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwt_cc
 
+  !> @brief GWT Model calculate flow
+  !!
+  !! Call the intercell flows (flow ja) subroutine
+  !<
   subroutine gwt_cq(this, icnvg, isuppress_output)
-! ******************************************************************************
-! gwt_cq --Groundwater transport model calculate flow
-! Subroutine: (1) Calculate intercell flows (flowja)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SparseModule, only: csr_diagsum
     ! -- dummy
@@ -559,7 +509,6 @@ subroutine gwt_cq(this, icnvg, isuppress_output)
     integer(I4B) :: i
     integer(I4B) :: ip
     class(BndType), pointer :: packobj
-! ------------------------------------------------------------------------------
     !
     ! -- Construct the flowja array.  Flowja is calculated each time, even if
     !    output is suppressed.  (flowja is positive into a cell.)  The diagonal
@@ -581,7 +530,7 @@ subroutine gwt_cq(this, icnvg, isuppress_output)
     !    conc solution.
     do ip = 1, this%bndlist%Count()
       packobj => GetBndFromList(this%bndlist, ip)
-      call packobj%bnd_cf(reset_mover=.false.)
+      call packobj%bnd_cf()
       call packobj%bnd_cq(this%x, this%flowja)
     end do
     !
@@ -594,15 +543,13 @@ subroutine gwt_cq(this, icnvg, isuppress_output)
     return
   end subroutine gwt_cq
 
+  !> @brief GWT Model Budget
+  !!
+  !! This subroutine:
+  !!  (1) calculates intercell flows (flowja)
+  !!  (2) calculates package contributions to the model budget
+  !<
   subroutine gwt_bd(this, icnvg, isuppress_output)
-! ******************************************************************************
-! gwt_bd --GroundWater Transport Model Budget
-! Subroutine: (1) Calculate intercell flows (flowja)
-!             (2) Calculate package contributions to model budget
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use ConstantsModule, only: DZERO
     ! -- dummy
     class(GwtModelType) :: this
@@ -611,7 +558,6 @@ subroutine gwt_bd(this, icnvg, isuppress_output)
     ! -- local
     integer(I4B) :: ip
     class(BndType), pointer :: packobj
-! ------------------------------------------------------------------------------
     !
     ! -- Save the solution convergence flag
     this%icnvg = icnvg
@@ -629,241 +575,43 @@ subroutine gwt_bd(this, icnvg, isuppress_output)
       packobj => GetBndFromList(this%bndlist, ip)
       call packobj%bnd_bd(this%budget)
     end do
-
     !
     ! -- Return
     return
   end subroutine gwt_bd
 
+  !> @brief Print and/or save model output
+  !!
+  !! Call the parent class output routine
+  !<
   subroutine gwt_ot(this)
-! ******************************************************************************
-! gwt_ot -- GroundWater Transport Model Output
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use TdisModule, only: kstp, kper, tdis_ot, endofperiod
     ! -- dummy
     class(GwtModelType) :: this
     ! -- local
-    integer(I4B) :: idvsave
-    integer(I4B) :: idvprint
     integer(I4B) :: icbcfl
     integer(I4B) :: icbcun
-    integer(I4B) :: ibudfl
-    integer(I4B) :: ipflag
-    ! -- formats
-    character(len=*), parameter :: fmtnocnvg = &
-      "(1X,/9X,'****FAILED TO MEET SOLVER CONVERGENCE CRITERIA IN TIME STEP ', &
-      &I0,' OF STRESS PERIOD ',I0,'****')"
-! ------------------------------------------------------------------------------
-    !
-    ! -- Set write and print flags
-    idvsave = 0
-    idvprint = 0
-    icbcfl = 0
-    ibudfl = 0
-    if (this%oc%oc_save('CONCENTRATION')) idvsave = 1
-    if (this%oc%oc_print('CONCENTRATION')) idvprint = 1
-    if (this%oc%oc_save('BUDGET')) icbcfl = 1
-    if (this%oc%oc_print('BUDGET')) ibudfl = 1
-    icbcun = this%oc%oc_save_unit('BUDGET')
-    !
-    ! -- Override ibudfl and idvprint flags for nonconvergence
-    !    and end of period
-    ibudfl = this%oc%set_print_flag('BUDGET', this%icnvg, endofperiod)
-    idvprint = this%oc%set_print_flag('CONCENTRATION', this%icnvg, endofperiod)
-    !
-    !   Calculate and save observations
-    call this%gwt_ot_obs()
-    !
-    !   Save and print flows
-    call this%gwt_ot_flow(icbcfl, ibudfl, icbcun)
     !
-    !   Save and print dependent variables
-    call this%gwt_ot_dv(idvsave, idvprint, ipflag)
     !
-    !   Print budget summaries
-    call this%gwt_ot_bdsummary(ibudfl, ipflag)
-    !
-    ! -- Timing Output; if any dependendent variables or budgets
-    !    are printed, then ipflag is set to 1.
-    if (ipflag == 1) call tdis_ot(this%iout)
-    !
-    ! -- Write non-convergence message
-    if (this%icnvg == 0) then
-      write (this%iout, fmtnocnvg) kstp, kper
-    end if
+    ! -- Initialize
+    icbcfl = 0
     !
-    ! -- Return
-    return
-  end subroutine gwt_ot
-
-  subroutine gwt_ot_obs(this)
-    class(GwtModelType) :: this
-    class(BndType), pointer :: packobj
-    integer(I4B) :: ip
-
-    ! -- Calculate and save observations
-    call this%obs%obs_bd()
-    call this%obs%obs_ot()
-
-    ! -- Calculate and save package obserations
-    do ip = 1, this%bndlist%Count()
-      packobj => GetBndFromList(this%bndlist, ip)
-      call packobj%bnd_bd_obs()
-      call packobj%bnd_ot_obs()
-    end do
-
-  end subroutine gwt_ot_obs
-
-  subroutine gwt_ot_flow(this, icbcfl, ibudfl, icbcun)
-    class(GwtModelType) :: this
-    integer(I4B), intent(in) :: icbcfl
-    integer(I4B), intent(in) :: ibudfl
-    integer(I4B), intent(in) :: icbcun
-    class(BndType), pointer :: packobj
-    integer(I4B) :: ip
-
-    ! -- Save GWT flows
-    call this%gwt_ot_flowja(this%nja, this%flowja, icbcfl, icbcun)
+    ! -- Because mst belongs to gwt, call mst_ot_flow directly (and not from parent)
+    if (this%oc%oc_save('BUDGET')) icbcfl = 1
+    icbcun = this%oc%oc_save_unit('BUDGET')
     if (this%inmst > 0) call this%mst%mst_ot_flow(icbcfl, icbcun)
-    if (this%infmi > 0) call this%fmi%fmi_ot_flow(icbcfl, icbcun)
-    if (this%inssm > 0) then
-      call this%ssm%ssm_ot_flow(icbcfl=icbcfl, ibudfl=0, icbcun=icbcun)
-    end if
-    do ip = 1, this%bndlist%Count()
-      packobj => GetBndFromList(this%bndlist, ip)
-      call packobj%bnd_ot_model_flows(icbcfl=icbcfl, ibudfl=0, icbcun=icbcun)
-    end do
-
-    ! -- Save advanced package flows
-    do ip = 1, this%bndlist%Count()
-      packobj => GetBndFromList(this%bndlist, ip)
-      call packobj%bnd_ot_package_flows(icbcfl=icbcfl, ibudfl=0)
-    end do
-    if (this%inmvt > 0) then
-      call this%mvt%mvt_ot_saveflow(icbcfl, ibudfl)
-    end if
-
-    ! -- Print GWF flows
-    ! no need to print flowja
-    ! no need to print mst
-    ! no need to print fmi
-    if (this%inssm > 0) then
-      call this%ssm%ssm_ot_flow(icbcfl=icbcfl, ibudfl=ibudfl, icbcun=0)
-    end if
-    do ip = 1, this%bndlist%Count()
-      packobj => GetBndFromList(this%bndlist, ip)
-      call packobj%bnd_ot_model_flows(icbcfl=icbcfl, ibudfl=ibudfl, icbcun=0)
-    end do
-
-    ! -- Print advanced package flows
-    do ip = 1, this%bndlist%Count()
-      packobj => GetBndFromList(this%bndlist, ip)
-      call packobj%bnd_ot_package_flows(icbcfl=0, ibudfl=ibudfl)
-    end do
-    if (this%inmvt > 0) then
-      call this%mvt%mvt_ot_printflow(icbcfl, ibudfl)
-    end if
-
-  end subroutine gwt_ot_flow
-
-  subroutine gwt_ot_flowja(this, nja, flowja, icbcfl, icbcun)
-! ******************************************************************************
-! gwt_ot_flowja -- Write intercell flows
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- dummy
-    class(GwtModelType) :: this
-    integer(I4B), intent(in) :: nja
-    real(DP), dimension(nja), intent(in) :: flowja
-    integer(I4B), intent(in) :: icbcfl
-    integer(I4B), intent(in) :: icbcun
-    ! -- local
-    integer(I4B) :: ibinun
-    ! -- formats
-! ------------------------------------------------------------------------------
     !
-    ! -- Set unit number for binary output
-    if (this%ipakcb < 0) then
-      ibinun = icbcun
-    elseif (this%ipakcb == 0) then
-      ibinun = 0
-    else
-      ibinun = this%ipakcb
-    end if
-    if (icbcfl == 0) ibinun = 0
-    !
-    ! -- Write the face flows if requested
-    if (ibinun /= 0) then
-      call this%dis%record_connection_array(flowja, ibinun, this%iout)
-    end if
+    ! -- Call parent class _ot routines.
+    call this%tsp_ot(this%inmst)
     !
     ! -- Return
     return
-  end subroutine gwt_ot_flowja
-
-  subroutine gwt_ot_dv(this, idvsave, idvprint, ipflag)
-    class(GwtModelType) :: this
-    integer(I4B), intent(in) :: idvsave
-    integer(I4B), intent(in) :: idvprint
-    integer(I4B), intent(inout) :: ipflag
-    class(BndType), pointer :: packobj
-    integer(I4B) :: ip
-
-    ! -- Print advanced package dependent variables
-    do ip = 1, this%bndlist%Count()
-      packobj => GetBndFromList(this%bndlist, ip)
-      call packobj%bnd_ot_dv(idvsave, idvprint)
-    end do
-
-    ! -- save head and print head
-    call this%oc%oc_ot(ipflag)
-
-  end subroutine gwt_ot_dv
-
-  subroutine gwt_ot_bdsummary(this, ibudfl, ipflag)
-    use TdisModule, only: kstp, kper, totim
-    class(GwtModelType) :: this
-    integer(I4B), intent(in) :: ibudfl
-    integer(I4B), intent(inout) :: ipflag
-    class(BndType), pointer :: packobj
-    integer(I4B) :: ip
-
-    !
-    ! -- Package budget summary
-    do ip = 1, this%bndlist%Count()
-      packobj => GetBndFromList(this%bndlist, ip)
-      call packobj%bnd_ot_bdsummary(kstp, kper, this%iout, ibudfl)
-    end do
-
-    ! -- mover budget summary
-    if (this%inmvt > 0) then
-      call this%mvt%mvt_ot_bdsummary(ibudfl)
-    end if
-
-    ! -- model budget summary
-    if (ibudfl /= 0) then
-      ipflag = 1
-      call this%budget%budget_ot(kstp, kper, this%iout)
-    end if
-
-    ! -- Write to budget csv
-    call this%budget%writecsv(totim)
-
-  end subroutine gwt_ot_bdsummary
+  end subroutine gwt_ot
 
+  !> @brief Deallocate
+  !!
+  !! Deallocate memmory at conclusion of model run
+  !<
   subroutine gwt_da(this)
-! ******************************************************************************
-! gwt_da -- Deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     use MemoryManagerExtModule, only: memorylist_remove
@@ -873,7 +621,6 @@ subroutine gwt_da(this)
     ! -- local
     integer(I4B) :: ip
     class(BndType), pointer :: packobj
-! ------------------------------------------------------------------------------
     !
     ! -- Deallocate idm memory
     call memorylist_remove(this%name, 'NAM', idm_context)
@@ -895,11 +642,10 @@ subroutine gwt_da(this)
     ! -- Internal package objects
     deallocate (this%dis)
     deallocate (this%ic)
-    deallocate (this%fmi)
-    deallocate (this%adv)
     deallocate (this%dsp)
     deallocate (this%ssm)
     deallocate (this%mst)
+    deallocate (this%adv)
     deallocate (this%mvt)
     deallocate (this%budget)
     deallocate (this%oc)
@@ -913,20 +659,16 @@ subroutine gwt_da(this)
     end do
     !
     ! -- Scalars
-    call mem_deallocate(this%inic)
-    call mem_deallocate(this%infmi)
-    call mem_deallocate(this%inadv)
     call mem_deallocate(this%indsp)
-    call mem_deallocate(this%inssm)
     call mem_deallocate(this%inmst)
-    call mem_deallocate(this%inmvt)
-    call mem_deallocate(this%inoc)
-    call mem_deallocate(this%inobs)
+    !
+    ! -- Parent class members
+    call this%TransportModelType%tsp_da()
     !
     ! -- NumericalModelType
     call this%NumericalModelType%model_da()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwt_da
 
@@ -935,8 +677,6 @@ end subroutine gwt_da
   !! This subroutine adds a budget entry to the flow budget.  It was added as
   !! a method for the gwt model object so that the exchange object could add its
   !! contributions.
-  !!
-  !! (1) adds the entry to the budget object
   !<
   subroutine gwt_bdentry(this, budterm, budtxt, rowlabel)
     ! -- modules
@@ -947,11 +687,10 @@ subroutine gwt_bdentry(this, budterm, budtxt, rowlabel)
     real(DP), dimension(:, :), intent(in) :: budterm
     character(len=LENBUDTXT), dimension(:), intent(in) :: budtxt
     character(len=*), intent(in) :: rowlabel
-! ------------------------------------------------------------------------------
     !
     call this%budget%addentry(budterm, delt, budtxt, rowlabel=rowlabel)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwt_bdentry
 
@@ -984,60 +723,43 @@ function gwt_get_iasym(this) result(iasym)
       if (packobj%iasym /= 0) iasym = 1
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end function gwt_get_iasym
 
+  !> Allocate memory for non-allocatable members
+  !!
+  !! A subroutine for allocating the scalars specific to the GWT model type.
+  !! Additional scalars used by the parent class are allocated by the parent
+  !! class.
+  !<
   subroutine allocate_scalars(this, modelname)
-! ******************************************************************************
-! allocate_scalars -- Allocate memory for non-allocatable members
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwtModelType) :: this
     character(len=*), intent(in) :: modelname
-! ------------------------------------------------------------------------------
     !
-    ! -- allocate members from parent class
-    call this%NumericalModelType%allocate_scalars(modelname)
+    ! -- allocate parent class scalars
+    call this%allocate_tsp_scalars(modelname)
     !
-    ! -- allocate members that are part of model class
-    call mem_allocate(this%inic, 'INIC', this%memoryPath)
-    call mem_allocate(this%infmi, 'INFMI', this%memoryPath)
-    call mem_allocate(this%inmvt, 'INMVT', this%memoryPath)
+    ! -- allocate additional members specific to GWT model type
     call mem_allocate(this%inmst, 'INMST', this%memoryPath)
-    call mem_allocate(this%inadv, 'INADV', this%memoryPath)
     call mem_allocate(this%indsp, 'INDSP', this%memoryPath)
-    call mem_allocate(this%inssm, 'INSSM', this%memoryPath)
-    call mem_allocate(this%inoc, 'INOC ', this%memoryPath)
-    call mem_allocate(this%inobs, 'INOBS', this%memoryPath)
     !
-    this%inic = 0
-    this%infmi = 0
-    this%inmvt = 0
     this%inmst = 0
-    this%inadv = 0
     this%indsp = 0
-    this%inssm = 0
-    this%inoc = 0
-    this%inobs = 0
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine allocate_scalars
 
-  subroutine package_create(this, filtyp, ipakid, ipaknum, pakname, inunit, &
-                            iout)
-! ******************************************************************************
-! package_create -- Create boundary condition packages for this model
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Create boundary condition packages for this model
+  !!
+  !! Call the package create routines for packages activated by the user.
+  !<
+  subroutine package_create(this, filtyp, ipakid, ipaknum, pakname, mempath, &
+                            inunit, iout)
     ! -- modules
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error
@@ -1056,32 +778,38 @@ subroutine package_create(this, filtyp, ipakid, ipaknum, pakname, inunit, &
     integer(I4B), intent(in) :: ipakid
     integer(I4B), intent(in) :: ipaknum
     character(len=*), intent(in) :: pakname
+    character(len=*), intent(in) :: mempath
     integer(I4B), intent(in) :: inunit
     integer(I4B), intent(in) :: iout
     ! -- local
     class(BndType), pointer :: packobj
     class(BndType), pointer :: packobj2
     integer(I4B) :: ip
-! ------------------------------------------------------------------------------
     !
     ! -- This part creates the package object
     select case (filtyp)
     case ('CNC6')
-      call cnc_create(packobj, ipakid, ipaknum, inunit, iout, this%name, pakname)
+      call cnc_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
+                      pakname, dvt, mempath)
     case ('SRC6')
-      call src_create(packobj, ipakid, ipaknum, inunit, iout, this%name, pakname)
+      call src_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
+                      this%depvartype, pakname)
     case ('LKT6')
       call lkt_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
-                      pakname, this%fmi)
+                      pakname, this%fmi, this%eqnsclfac, this%depvartype, &
+                      this%depvarunit, this%depvarunitabbrev)
     case ('SFT6')
       call sft_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
-                      pakname, this%fmi)
+                      pakname, this%fmi, this%eqnsclfac, this%depvartype, &
+                      this%depvarunit, this%depvarunitabbrev)
     case ('MWT6')
       call mwt_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
-                      pakname, this%fmi)
+                      pakname, this%fmi, this%eqnsclfac, this%depvartype, &
+                      this%depvarunit, this%depvarunitabbrev)
     case ('UZT6')
       call uzt_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
-                      pakname, this%fmi)
+                      pakname, this%fmi, this%eqnsclfac, this%depvartype, &
+                      this%depvarunit, this%depvarunitabbrev)
     case ('IST6')
       call ist_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
                       pakname, this%fmi, this%mst)
@@ -1105,66 +833,25 @@ subroutine package_create(this, filtyp, ipakid, ipaknum, pakname, inunit, &
     end do
     call AddBndToList(this%bndlist, packobj)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine package_create
 
-  subroutine ftype_check(this, indis)
-! ******************************************************************************
-! ftype_check -- Check to make sure required input files have been specified
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use ConstantsModule, only: LINELENGTH
-    use SimModule, only: store_error, count_errors, store_error_filename
-    ! -- dummy
-    class(GwtModelType) :: this
-    integer(I4B), intent(in) :: indis
-    ! -- local
-    character(len=LINELENGTH) :: errmsg
-! ------------------------------------------------------------------------------
-    !
-    ! -- Check for IC6, DIS(u), and MST. Stop if not present.
-    if (this%inic == 0) then
-      write (errmsg, '(a)') &
-        'Initial conditions (IC6) package not specified.'
-      call store_error(errmsg)
-    end if
-    if (indis == 0) then
-      write (errmsg, '(a)') &
-        'Discretization (DIS6 or DISU6) package not specified.'
-      call store_error(errmsg)
-    end if
-    if (this%inmst == 0) then
-      write (errmsg, '(a)') 'Mass storage and transfer (MST6) &
-        &package not specified.'
-      call store_error(errmsg)
-    end if
-    !
-    if (count_errors() > 0) then
-      write (errmsg, '(a)') 'Required package(s) not specified.'
-      call store_error(errmsg)
-      call store_error_filename(this%filename)
-    end if
-    !
-    ! -- return
-    return
-  end subroutine ftype_check
-
   !> @brief Cast to GwtModelType
+  !<
   function CastAsGwtModel(model) result(gwtmodel)
     class(*), pointer :: model !< The object to be cast
     class(GwtModelType), pointer :: gwtmodel !< The GWT model
-
+    !
     gwtmodel => null()
     if (.not. associated(model)) return
     select type (model)
     type is (GwtModelType)
       gwtmodel => model
     end select
-
+    !
+    ! -- Return
+    return
   end function CastAsGwtModel
 
   !> @brief Source package info and begin to process
@@ -1192,7 +879,7 @@ subroutine create_bndpkgs(this, bndpkgs, pkgtypes, pkgnames, &
     character(len=LENMEMPATH) :: mempath
     integer(I4B), pointer :: inunit
     integer(I4B) :: n
-
+    !
     if (allocated(bndpkgs)) then
       !
       ! -- create stress packages
@@ -1210,8 +897,8 @@ subroutine create_bndpkgs(this, bndpkgs, pkgtypes, pkgnames, &
           bndptype = pkgtype
         end if
         !
-        call this%package_create(pkgtype, ipakid, ipaknum, pkgname, inunit, &
-                                 this%iout)
+        call this%package_create(pkgtype, ipakid, ipaknum, pkgname, mempath, &
+                                 inunit, this%iout)
         ipakid = ipakid + 1
         ipaknum = ipaknum + 1
       end do
@@ -1220,13 +907,13 @@ subroutine create_bndpkgs(this, bndpkgs, pkgtypes, pkgnames, &
       deallocate (bndpkgs)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine create_bndpkgs
 
   !> @brief Source package info and begin to process
   !<
-  subroutine create_packages(this)
+  subroutine create_gwt_packages(this, indis)
     ! -- modules
     use ConstantsModule, only: LINELENGTH, LENPACKAGENAME
     use CharacterStringModule, only: CharacterStringType
@@ -1234,20 +921,11 @@ subroutine create_packages(this)
     use MemoryManagerModule, only: mem_setptr
     use MemoryHelperModule, only: create_mem_path
     use SimVariablesModule, only: idm_context
-    use GwfDisModule, only: dis_cr
-    use GwfDisvModule, only: disv_cr
-    use GwfDisuModule, only: disu_cr
-    use GwtIcModule, only: ic_cr
-    use GwtFmiModule, only: fmi_cr
     use GwtMstModule, only: mst_cr
-    use GwtAdvModule, only: adv_cr
     use GwtDspModule, only: dsp_cr
-    use GwtSsmModule, only: ssm_cr
-    use GwtMvtModule, only: mvt_cr
-    use GwtOcModule, only: oc_cr
-    use GwtObsModule, only: gwt_obs_cr
     ! -- dummy
     class(GwtModelType) :: this
+    integer(I4B), intent(in) :: indis
     ! -- local
     type(CharacterStringType), dimension(:), contiguous, &
       pointer :: pkgtypes => null()
@@ -1264,7 +942,6 @@ subroutine create_packages(this)
     integer(I4B), pointer :: inunit
     integer(I4B), dimension(:), allocatable :: bndpkgs
     integer(I4B) :: n
-    integer(I4B) :: indis = 0 ! DIS enabled flag
     character(len=LENMEMPATH) :: mempathdsp = ''
     !
     ! -- set input memory paths, input/model and input/model/namfile
@@ -1286,34 +963,11 @@ subroutine create_packages(this)
       !
       ! -- create dis package as it is a prerequisite for other packages
       select case (pkgtype)
-      case ('DIS6')
-        indis = 1
-        call dis_cr(this%dis, this%name, mempath, indis, this%iout)
-      case ('DISV6')
-        indis = 1
-        call disv_cr(this%dis, this%name, mempath, indis, this%iout)
-      case ('DISU6')
-        indis = 1
-        call disu_cr(this%dis, this%name, mempath, indis, this%iout)
-      case ('IC6')
-        this%inic = inunit
-      case ('FMI6')
-        this%infmi = inunit
-      case ('MVT6')
-        this%inmvt = inunit
       case ('MST6')
         this%inmst = inunit
-      case ('ADV6')
-        this%inadv = inunit
       case ('DSP6')
         this%indsp = 1
         mempathdsp = mempath
-      case ('SSM6')
-        this%inssm = inunit
-      case ('OC6')
-        this%inoc = inunit
-      case ('OBS6')
-        this%inobs = inunit
       case ('CNC6', 'SRC6', 'LKT6', 'SFT6', &
             'MWT6', 'UZT6', 'IST6', 'API6')
         call expandarray(bndpkgs)
@@ -1324,107 +978,17 @@ subroutine create_packages(this)
     end do
     !
     ! -- Create packages that are tied directly to model
-    call ic_cr(this%ic, this%name, this%inic, this%iout, this%dis)
-    call fmi_cr(this%fmi, this%name, this%infmi, this%iout)
     call mst_cr(this%mst, this%name, this%inmst, this%iout, this%fmi)
-    call adv_cr(this%adv, this%name, this%inadv, this%iout, this%fmi)
     call dsp_cr(this%dsp, this%name, mempathdsp, this%indsp, this%iout, &
                 this%fmi)
-    call ssm_cr(this%ssm, this%name, this%inssm, this%iout, this%fmi)
-    call mvt_cr(this%mvt, this%name, this%inmvt, this%iout, this%fmi)
-    call oc_cr(this%oc, this%name, this%inoc, this%iout)
-    call gwt_obs_cr(this%obs, this%inobs)
     !
     ! -- Check to make sure that required ftype's have been specified
-    call this%ftype_check(indis)
+    call this%ftype_check(indis, this%inmst)
     !
     call this%create_bndpkgs(bndpkgs, pkgtypes, pkgnames, mempaths, inunits)
-
-  end subroutine create_packages
-
-  subroutine create_lstfile(this, lst_fname, model_fname, defined)
-    ! -- modules
-    use KindModule, only: LGP
-    use InputOutputModule, only: openfile, getunit
-    ! -- dummy
-    class(GwtModelType) :: this
-    character(len=*), intent(inout) :: lst_fname
-    character(len=*), intent(in) :: model_fname
-    logical(LGP), intent(in) :: defined
-    ! -- local
-    integer(I4B) :: i, istart, istop
-    !
-    ! -- set list file name if not provided
-    if (.not. defined) then
-      !
-      ! -- initialize
-      lst_fname = ' '
-      istart = 0
-      istop = len_trim(model_fname)
-      !
-      ! -- identify '.' character position from back of string
-      do i = istop, 1, -1
-        if (model_fname(i:i) == '.') then
-          istart = i
-          exit
-        end if
-      end do
-      !
-      ! -- if not found start from string end
-      if (istart == 0) istart = istop + 1
-      !
-      ! -- set list file name
-      lst_fname = model_fname(1:istart)
-      istop = istart + 3
-      lst_fname(istart:istop) = '.lst'
-    end if
     !
-    ! -- create the list file
-    this%iout = getunit()
-    call openfile(this%iout, 0, lst_fname, 'LIST', filstat_opt='REPLACE')
-    !
-    ! -- write list file header
-    call write_listfile_header(this%iout, 'GROUNDWATER TRANSPORT MODEL (GWT)')
-    !
-    ! -- return
+    ! -- Return
     return
-  end subroutine create_lstfile
-
-  !> @brief Write model namfile options to list file
-  !<
-  subroutine log_namfile_options(this, found)
-    use GwfNamInputModule, only: GwfNamParamFoundType
-    class(GwtModelType) :: this
-    type(GwfNamParamFoundType), intent(in) :: found
-
-    write (this%iout, '(1x,a)') 'NAMEFILE OPTIONS:'
-
-    if (found%newton) then
-      write (this%iout, '(4x,a)') &
-        'NEWTON-RAPHSON method enabled for the model.'
-      if (found%under_relaxation) then
-        write (this%iout, '(4x,a,a)') &
-          'NEWTON-RAPHSON UNDER-RELAXATION based on the bottom ', &
-          'elevation of the model will be applied to the model.'
-      end if
-    end if
-
-    if (found%print_input) then
-      write (this%iout, '(4x,a)') 'STRESS PACKAGE INPUT WILL BE PRINTED '// &
-        'FOR ALL MODEL STRESS PACKAGES'
-    end if
-
-    if (found%print_flows) then
-      write (this%iout, '(4x,a)') 'PACKAGE FLOWS WILL BE PRINTED '// &
-        'FOR ALL MODEL PACKAGES'
-    end if
-
-    if (found%save_flows) then
-      write (this%iout, '(4x,a)') &
-        'FLOWS WILL BE SAVED TO BUDGET FILE SPECIFIED IN OUTPUT CONTROL'
-    end if
-
-    write (this%iout, '(1x,a)') 'END NAMEFILE OPTIONS:'
-  end subroutine log_namfile_options
+  end subroutine create_gwt_packages
 
 end module GwtModule
diff --git a/src/Model/GroundWaterTransport/gwt1cnc1.f90 b/src/Model/GroundWaterTransport/gwt1cnc1.f90
index 5fc5378f078..366a094c2a1 100644
--- a/src/Model/GroundWaterTransport/gwt1cnc1.f90
+++ b/src/Model/GroundWaterTransport/gwt1cnc1.f90
@@ -2,12 +2,16 @@ module GwtCncModule
   !
   use KindModule, only: DP, I4B
   use ConstantsModule, only: DZERO, DONE, NAMEDBOUNDFLAG, LENFTYPE, &
-                             LENPACKAGENAME
+                             LENPACKAGENAME, LENVARNAME
+  use SimVariablesModule, only: errmsg
+  use SimModule, only: count_errors, store_error, store_error_filename
   use ObsModule, only: DefaultObsIdProcessor
   use BndModule, only: BndType
+  use BndExtModule, only: BndExtType
   use ObserveModule, only: ObserveType
   use TimeSeriesLinkModule, only: TimeSeriesLinkType, &
                                   GetTimeSeriesLinkFromList
+  use InputOutputModule, only: str_pad_left
   use MatrixBaseModule
   !
   implicit none
@@ -18,9 +22,12 @@ module GwtCncModule
   character(len=LENFTYPE) :: ftype = 'CNC'
   character(len=LENPACKAGENAME) :: text = '             CNC'
   !
-  type, extends(BndType) :: GwtCncType
+  type, extends(BndExtType) :: GwtCncType
+
+    real(DP), dimension(:), pointer, contiguous :: tspvar => null() !< constant concentration array
     real(DP), dimension(:), pointer, contiguous :: ratecncin => null() !simulated flows into constant conc (excluding other concs)
     real(DP), dimension(:), pointer, contiguous :: ratecncout => null() !simulated flows out of constant conc (excluding to other concs)
+    character(len=LENVARNAME) :: depvartype = '' !< stores string of dependent variable type, depending on model type
   contains
     procedure :: bnd_rp => cnc_rp
     procedure :: bnd_ad => cnc_ad
@@ -31,6 +38,8 @@ module GwtCncModule
     procedure :: bnd_da => cnc_da
     procedure :: allocate_arrays => cnc_allocate_arrays
     procedure :: define_listlabel
+    procedure :: bound_value => cnc_bound_value
+    procedure :: conc_mult
     ! -- methods for observations
     procedure, public :: bnd_obs_supported => cnc_obs_supported
     procedure, public :: bnd_df_obs => cnc_df_obs
@@ -40,15 +49,12 @@ module GwtCncModule
 
 contains
 
-  subroutine cnc_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
-! ******************************************************************************
-! cnc_create -- Create a New Constant Concentration Package
-! Subroutine: (1) create new-style package
-!             (2) point packobj to the new package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Create a new constant concentration or temperature package
+  !!
+  !! Routine points packobj to the newly created package
+  !<
+  subroutine cnc_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
+                        depvartype, mempath)
     ! -- dummy
     class(BndType), pointer :: packobj
     integer(I4B), intent(in) :: id
@@ -57,20 +63,21 @@ subroutine cnc_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     integer(I4B), intent(in) :: iout
     character(len=*), intent(in) :: namemodel
     character(len=*), intent(in) :: pakname
+    character(len=LENVARNAME), intent(in) :: depvartype
+    character(len=*), intent(in) :: mempath
     ! -- local
     type(GwtCncType), pointer :: cncobj
-! ------------------------------------------------------------------------------
     !
     ! -- allocate the object and assign values to object variables
     allocate (cncobj)
     packobj => cncobj
     !
     ! -- create name and memory path
-    call packobj%set_names(ibcnum, namemodel, pakname, ftype)
+    call packobj%set_names(ibcnum, namemodel, pakname, ftype, mempath)
     packobj%text = text
     !
     ! -- allocate scalars
-    call packobj%allocate_scalars()
+    call cncobj%allocate_scalars()
     !
     ! -- initialize package
     call packobj%pack_initialize()
@@ -80,32 +87,29 @@ subroutine cnc_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     packobj%iout = iout
     packobj%id = id
     packobj%ibcnum = ibcnum
-    packobj%ncolbnd = 1
-    packobj%iscloc = 1
     !
-    ! -- return
+    ! -- Store the appropriate label based on the dependent variable
+    cncobj%depvartype = depvartype
+    !
+    ! -- Return
     return
   end subroutine cnc_create
 
+  !> @brief Allocate arrays specific to the constant concentration/tempeature
+  !! package.
+  !<
   subroutine cnc_allocate_arrays(this, nodelist, auxvar)
-! ******************************************************************************
-! allocate_scalars -- allocate arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
-    use MemoryManagerModule, only: mem_allocate
+    use MemoryManagerModule, only: mem_allocate, mem_setptr, mem_checkin
     ! -- dummy
     class(GwtCncType) :: this
     integer(I4B), dimension(:), pointer, contiguous, optional :: nodelist
     real(DP), dimension(:, :), pointer, contiguous, optional :: auxvar
     ! -- local
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     ! -- call standard BndType allocate scalars
-    call this%BndType%allocate_arrays()
+    call this%BndExtType%allocate_arrays(nodelist, auxvar)
     !
     ! -- allocate ratecncex
     call mem_allocate(this%ratecncin, this%maxbound, 'RATECNCIN', this%memoryPath)
@@ -115,24 +119,28 @@ subroutine cnc_allocate_arrays(this, nodelist, auxvar)
       this%ratecncin(i) = DZERO
       this%ratecncout(i) = DZERO
     end do
+    ! -- set constant head array input context pointer
+    call mem_setptr(this%tspvar, 'TSPVAR', this%input_mempath)
+    !
+    ! -- checkin constant head array input context pointer
+    call mem_checkin(this%tspvar, 'TSPVAR', this%memoryPath, &
+                     'TSPVAR', this%input_mempath)
     !
-    ! -- return
+    !
+    ! -- Return
     return
   end subroutine cnc_allocate_arrays
 
+  !> @brief Constant concentration/temperature read and prepare (rp) routine
+  !<
   subroutine cnc_rp(this)
-! ******************************************************************************
-! cnc_rp -- Read and prepare
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use SimModule, only: store_error
+    use InputOutputModule, only: lowcase
     implicit none
     class(GwtCncType), intent(inout) :: this
     integer(I4B) :: i, node, ibd, ierr
     character(len=30) :: nodestr
-! ------------------------------------------------------------------------------
+    character(len=LENVARNAME) :: dvtype
     !
     ! -- Reset previous CNCs to active cell
     do i = 1, this%nbound
@@ -141,7 +149,7 @@ subroutine cnc_rp(this)
     end do
     !
     ! -- Call the parent class read and prepare
-    call this%BndType%bnd_rp()
+    call this%BndExtType%bnd_rp()
     !
     ! -- Set ibound to -(ibcnum + 1) for constant concentration cells
     ierr = 0
@@ -150,8 +158,10 @@ subroutine cnc_rp(this)
       ibd = this%ibound(node)
       if (ibd < 0) then
         call this%dis%noder_to_string(node, nodestr)
-        call store_error('Cell is already a constant concentration: ' &
-                         //trim(adjustl(nodestr)))
+        dvtype = trim(this%depvartype)
+        call lowcase(dvtype)
+        call store_error('Cell is already a constant ' &
+                         //dvtype//': '//trim(adjustl(nodestr)))
         ierr = ierr + 1
       else
         this%ibound(node) = -this%ibcnum
@@ -160,20 +170,23 @@ subroutine cnc_rp(this)
     !
     ! -- Stop if errors detected
     if (ierr > 0) then
-      call this%parser%StoreErrorUnit()
+      call store_error_filename(this%input_fname)
+    end if
+    !
+    ! -- Write the list to iout if requested
+    if (this%iprpak /= 0) then
+      call this%write_list()
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine cnc_rp
 
+  !> @brief Constant concentration/temperature package advance routine
+  !!
+  !! Add package connections to matrix
+  !<
   subroutine cnc_ad(this)
-! ******************************************************************************
-! cnc_ad -- Advance
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtCncType) :: this
@@ -181,7 +194,6 @@ subroutine cnc_ad(this)
     integer(I4B) :: i, node
     real(DP) :: cb
     ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- Advance the time series
     call this%TsManager%ad()
@@ -189,7 +201,8 @@ subroutine cnc_ad(this)
     ! -- Process each entry in the constant concentration cell list
     do i = 1, this%nbound
       node = this%nodelist(i)
-      cb = this%bound(1, i)
+      cb = this%conc_mult(i)
+      !
       this%xnew(node) = cb
       this%xold(node) = this%xnew(node)
     end do
@@ -199,59 +212,51 @@ subroutine cnc_ad(this)
     !    "current" value.
     call this%obs%obs_ad()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine cnc_ad
 
+  !> @brief Check constant concentration/temperature boundary condition data
+  !<
   subroutine cnc_ck(this)
-! ******************************************************************************
-! cnc_ck -- Check cnc boundary condition data
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
-    use ConstantsModule, only: LINELENGTH
-    use SimModule, only: store_error, count_errors, store_error_unit
     ! -- dummy
     class(GwtCncType), intent(inout) :: this
     ! -- local
-    character(len=LINELENGTH) :: errmsg
     character(len=30) :: nodestr
     integer(I4B) :: i
     integer(I4B) :: node
     ! -- formats
     character(len=*), parameter :: fmtcncerr = &
-      &"('CNC boundary ',i0,' conc (',g0,') is less than zero for cell', a)"
-! ------------------------------------------------------------------------------
+      &"('Specified dependent variable boundary ',i0, &
+      &' conc (',g0,') is less than zero for cell', a)"
     !
     ! -- check stress period data
     do i = 1, this%nbound
       node = this%nodelist(i)
       ! -- accumulate errors
-      if (this%bound(1, i) < DZERO) then
+      if (this%conc_mult(i) < DZERO) then
         call this%dis%noder_to_string(node, nodestr)
-        write (errmsg, fmt=fmtcncerr) i, this%bound(1, i), trim(nodestr)
+        write (errmsg, fmt=fmtcncerr) i, this%tspvar(i), trim(nodestr)
         call store_error(errmsg)
       end if
     end do
     !
     ! -- write summary of cnc package error messages
     if (count_errors() > 0) then
-      call this%parser%StoreErrorUnit()
+      call store_error_filename(this%input_fname)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine cnc_ck
 
+  !> @brief Override bnd_fc and do nothing
+  !!
+  !! For constant concentration/temperature boundary type, the call to bnd_fc
+  !! needs to be overwritten to prevent logic found in bnd from being executed
+  !<
   subroutine cnc_fc(this, rhs, ia, idxglo, matrix_sln)
-! **************************************************************************
-! cnc_fc -- Override bnd_fc and do nothing
-! **************************************************************************
-!
-!    SPECIFICATIONS:
-! --------------------------------------------------------------------------
     ! -- dummy
     class(GwtCncType) :: this
     real(DP), dimension(:), intent(inout) :: rhs
@@ -259,19 +264,17 @@ subroutine cnc_fc(this, rhs, ia, idxglo, matrix_sln)
     integer(I4B), dimension(:), intent(in) :: idxglo
     class(MatrixBaseType), pointer :: matrix_sln
     ! -- local
-! --------------------------------------------------------------------------
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine cnc_fc
 
+  !> @brief Calculate flow associated with constant concentration/temperature
+  !! boundary
+  !!
+  !! This method overrides bnd_cq()
+  !<
   subroutine cnc_cq(this, x, flowja, iadv)
-! ******************************************************************************
-! cnc_cq -- Calculate constant concenration flow.  This method overrides bnd_cq().
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtCncType), intent(inout) :: this
@@ -287,7 +290,6 @@ subroutine cnc_cq(this, x, flowja, iadv)
     real(DP) :: rate
     real(DP) :: ratein, rateout
     real(DP) :: q
-! ------------------------------------------------------------------------------
     !
     ! -- If no boundaries, skip flow calculations.
     if (this%nbound > 0) then
@@ -332,61 +334,65 @@ subroutine cnc_cq(this, x, flowja, iadv)
       !
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine cnc_cq
 
+  !> @brief Add package ratin/ratout to model budget
+  !<
   subroutine cnc_bd(this, model_budget)
-    ! -- add package ratin/ratout to model budget
+    ! -- modules
     use TdisModule, only: delt
     use BudgetModule, only: BudgetType, rate_accumulator
+    ! -- dummy
     class(GwtCncType) :: this
+    ! -- local
     type(BudgetType), intent(inout) :: model_budget
     real(DP) :: ratin
     real(DP) :: ratout
     real(DP) :: dum
     integer(I4B) :: isuppress_output
+    !
     isuppress_output = 0
     call rate_accumulator(this%ratecncin(1:this%nbound), ratin, dum)
     call rate_accumulator(this%ratecncout(1:this%nbound), ratout, dum)
     call model_budget%addentry(ratin, ratout, delt, this%text, &
                                isuppress_output, this%packName)
+    !
+    ! -- Return
+    return
   end subroutine cnc_bd
 
+  !> @brief Deallocate memory
+  !!
+  !!  Method to deallocate memory for the package.
+  !<
   subroutine cnc_da(this)
-! ******************************************************************************
-! cnc_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(GwtCncType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Deallocate parent package
-    call this%BndType%bnd_da()
+    call this%BndExtType%bnd_da()
     !
     ! -- arrays
     call mem_deallocate(this%ratecncin)
     call mem_deallocate(this%ratecncout)
+    call mem_deallocate(this%tspvar, 'TSPVAR', this%memoryPath)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine cnc_da
 
+  !> @brief Define labels used in list file
+  !!
+  !! Define the list heading that is written to iout when PRINT_INPUT option
+  !! is used.
+  !<
   subroutine define_listlabel(this)
-! ******************************************************************************
-! define_listlabel -- Define the list heading that is written to iout when
-!   PRINT_INPUT option is used.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     class(GwtCncType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- create the header list label
     this%listlabel = trim(this%filtyp)//' NO.'
@@ -400,76 +406,67 @@ subroutine define_listlabel(this)
     else
       write (this%listlabel, '(a, a7)') trim(this%listlabel), 'NODE'
     end if
-    write (this%listlabel, '(a, a16)') trim(this%listlabel), 'CONCENTRATION'
+    write (this%listlabel, '(a, a16)') trim(this%listlabel), &
+      trim(this%depvartype)
     if (this%inamedbound == 1) then
       write (this%listlabel, '(a, a16)') trim(this%listlabel), 'BOUNDARY NAME'
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine define_listlabel
 
-  ! -- Procedures related to observations
-
+  !> @brief Procedure related to observation processing
+  !!
+  !! This routine:
+  !!   - returns true because the SDV package supports observations,
+  !!   - overrides packagetype%_obs_supported()
   logical function cnc_obs_supported(this)
-! ******************************************************************************
-! cnc_obs_supported
-!   -- Return true because CNC package supports observations.
-!   -- Overrides packagetype%_obs_supported()
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtCncType) :: this
-! ------------------------------------------------------------------------------
     !
     cnc_obs_supported = .true.
     !
-    ! -- return
+    ! -- Return
     return
   end function cnc_obs_supported
 
+  !> @brief Procedure related to observation processing
+  !!
+  !! This routine:
+  !!   - defines observations
+  !!   - stores observation types supported by either of the SDV packages
+  !!     (CNC or CNT),
+  !!   - overrides BndExtType%bnd_df_obs
+  !<
   subroutine cnc_df_obs(this)
-! ******************************************************************************
-! cnc_df_obs (implements bnd_df_obs)
-!   -- Store observation type supported by CNC package.
-!   -- Overrides BndType%bnd_df_obs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtCncType) :: this
     ! -- local
     integer(I4B) :: indx
-! ------------------------------------------------------------------------------
     !
-    call this%obs%StoreObsType('cnc', .true., indx)
+    call this%obs%StoreObsType(this%filtyp, .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => DefaultObsIdProcessor
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine cnc_df_obs
 
   ! -- Procedure related to time series
 
+  !> @brief Procedure related to time series
+  !!
+  !! Assign tsLink%Text appropriately for all time series in use by package.
+  !! For any specified dependent variable package, for example either the
+  !! constant concentration or constant temperature packages, the dependent
+  !! variable can be controlled by time series.
+  !<
   subroutine cnc_rp_ts(this)
-! ******************************************************************************
-! -- Assign tsLink%Text appropriately for
-!    all time series in use by package.
-!    In CNC package variable CONCENTRATION
-!    can be controlled by time series.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtCncType), intent(inout) :: this
     ! -- local
     integer(I4B) :: i, nlinks
     type(TimeSeriesLinkType), pointer :: tslink => null()
-! ------------------------------------------------------------------------------
     !
     nlinks = this%TsManager%boundtslinks%Count()
     do i = 1, nlinks
@@ -477,13 +474,63 @@ subroutine cnc_rp_ts(this)
       if (associated(tslink)) then
         select case (tslink%JCol)
         case (1)
-          tslink%Text = 'CONCENTRATION'
+          tslink%Text = trim(this%depvartype)
         end select
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine cnc_rp_ts
 
+  !> @brief Apply auxiliary multiplier to specified concentration if
+  !< appropriate
+  function conc_mult(this, row) result(conc)
+    ! -- modules
+    use ConstantsModule, only: DZERO
+    ! -- dummy variables
+    class(GwtCncType), intent(inout) :: this !< BndExtType object
+    integer(I4B), intent(in) :: row
+    ! -- result
+    real(DP) :: conc
+    !
+    if (this%iauxmultcol > 0) then
+      conc = this%tspvar(row) * this%auxvar(this%iauxmultcol, row)
+    else
+      conc = this%tspvar(row)
+    end if
+    !
+    ! -- Return
+    return
+  end function conc_mult
+
+  !> @ brief Return a bound value
+  !!
+  !!  Return a bound value associated with an ncolbnd index and row.
+  !<
+  function cnc_bound_value(this, col, row) result(bndval)
+    ! -- modules
+    use ConstantsModule, only: DZERO
+    ! -- dummy variables
+    class(GwtCncType), intent(inout) :: this !< BndExtType object
+    integer(I4B), intent(in) :: col
+    integer(I4B), intent(in) :: row
+    ! -- result
+    real(DP) :: bndval
+    !
+    select case (col)
+    case (1)
+      bndval = this%conc_mult(row)
+    case default
+      write (errmsg, '(3a)') 'Programming error. ', &
+               & adjustl(trim(this%filtyp)), ' bound value requested column '&
+               &'outside range of ncolbnd (1).'
+      call store_error(errmsg)
+      call store_error_filename(this%input_fname)
+    end select
+    !
+    ! -- Return
+    return
+  end function cnc_bound_value
+
 end module GwtCncModule
diff --git a/src/Model/GroundWaterTransport/gwt1cnc1idm.f90 b/src/Model/GroundWaterTransport/gwt1cnc1idm.f90
new file mode 100644
index 00000000000..2edbab4bfe5
--- /dev/null
+++ b/src/Model/GroundWaterTransport/gwt1cnc1idm.f90
@@ -0,0 +1,411 @@
+! ** Do Not Modify! MODFLOW 6 system generated file. **
+module GwtCncInputModule
+  use ConstantsModule, only: LENVARNAME
+  use InputDefinitionModule, only: InputParamDefinitionType, &
+                                   InputBlockDefinitionType
+  private
+  public gwt_cnc_param_definitions
+  public gwt_cnc_aggregate_definitions
+  public gwt_cnc_block_definitions
+  public GwtCncParamFoundType
+  public gwt_cnc_multi_package
+
+  type GwtCncParamFoundType
+    logical :: auxiliary = .false.
+    logical :: auxmultname = .false.
+    logical :: boundnames = .false.
+    logical :: iprflow = .false.
+    logical :: ipakcb = .false.
+    logical :: iprpak = .false.
+    logical :: ts_filerecord = .false.
+    logical :: ts6 = .false.
+    logical :: filein = .false.
+    logical :: ts6_filename = .false.
+    logical :: obs_filerecord = .false.
+    logical :: obs6 = .false.
+    logical :: obs6_filename = .false.
+    logical :: maxbound = .false.
+    logical :: cellid = .false.
+    logical :: tspvar = .false.
+    logical :: auxvar = .false.
+    logical :: boundname = .false.
+  end type GwtCncParamFoundType
+
+  logical :: gwt_cnc_multi_package = .true.
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_auxiliary = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXILIARY', & ! tag name
+    'AUXILIARY', & ! fortran variable
+    'STRING', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_auxmultname = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'OPTIONS', & ! block
+    'AUXMULTNAME', & ! tag name
+    'AUXMULTNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_boundnames = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'OPTIONS', & ! block
+    'BOUNDNAMES', & ! tag name
+    'BOUNDNAMES', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_iprflow = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_INPUT', & ! tag name
+    'IPRFLOW', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_ipakcb = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'OPTIONS', & ! block
+    'PRINT_FLOWS', & ! tag name
+    'IPAKCB', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_iprpak = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'OPTIONS', & ! block
+    'SAVE_FLOWS', & ! tag name
+    'IPRPAK', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_ts_filerecord = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS_FILERECORD', & ! tag name
+    'TS_FILERECORD', & ! fortran variable
+    'RECORD TS6 FILEIN TS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_ts6 = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS6', & ! tag name
+    'TS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_filein = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'OPTIONS', & ! block
+    'FILEIN', & ! tag name
+    'FILEIN', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_ts6_filename = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'OPTIONS', & ! block
+    'TS6_FILENAME', & ! tag name
+    'TS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_obs_filerecord = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS_FILERECORD', & ! tag name
+    'OBS_FILERECORD', & ! fortran variable
+    'RECORD OBS6 FILEIN OBS6_FILENAME', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_obs6 = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6', & ! tag name
+    'OBS6', & ! fortran variable
+    'KEYWORD', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_obs6_filename = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'OPTIONS', & ! block
+    'OBS6_FILENAME', & ! tag name
+    'OBS6_FILENAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .true., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_maxbound = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'DIMENSIONS', & ! block
+    'MAXBOUND', & ! tag name
+    'MAXBOUND', & ! fortran variable
+    'INTEGER', & ! type
+    '', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_cellid = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'PERIOD', & ! block
+    'CELLID', & ! tag name
+    'CELLID', & ! fortran variable
+    'INTEGER1D', & ! type
+    'NCELLDIM', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_tspvar = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'PERIOD', & ! block
+    'CONC', & ! tag name
+    'TSPVAR', & ! fortran variable
+    'DOUBLE', & ! type
+    '', & ! shape
+    .true., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_auxvar = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'PERIOD', & ! block
+    'AUX', & ! tag name
+    'AUXVAR', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NAUX', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .true. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_boundname = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'PERIOD', & ! block
+    'BOUNDNAME', & ! tag name
+    'BOUNDNAME', & ! fortran variable
+    'STRING', & ! type
+    '', & ! shape
+    .false., & ! required
+    .true., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwt_cnc_param_definitions(*) = &
+    [ &
+    gwtcnc_auxiliary, &
+    gwtcnc_auxmultname, &
+    gwtcnc_boundnames, &
+    gwtcnc_iprflow, &
+    gwtcnc_ipakcb, &
+    gwtcnc_iprpak, &
+    gwtcnc_ts_filerecord, &
+    gwtcnc_ts6, &
+    gwtcnc_filein, &
+    gwtcnc_ts6_filename, &
+    gwtcnc_obs_filerecord, &
+    gwtcnc_obs6, &
+    gwtcnc_obs6_filename, &
+    gwtcnc_maxbound, &
+    gwtcnc_cellid, &
+    gwtcnc_tspvar, &
+    gwtcnc_auxvar, &
+    gwtcnc_boundname &
+    ]
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtcnc_spd = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'CNC', & ! subcomponent
+    'PERIOD', & ! block
+    'STRESS_PERIOD_DATA', & ! tag name
+    'SPD', & ! fortran variable
+    'RECARRAY CELLID CONC AUX BOUNDNAME', & ! type
+    'MAXBOUND', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwt_cnc_aggregate_definitions(*) = &
+    [ &
+    gwtcnc_spd &
+    ]
+
+  type(InputBlockDefinitionType), parameter :: &
+    gwt_cnc_block_definitions(*) = &
+    [ &
+    InputBlockDefinitionType( &
+    'OPTIONS', & ! blockname
+    .false., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'DIMENSIONS', & ! blockname
+    .true., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'PERIOD', & ! blockname
+    .true., & ! required
+    .true., & ! aggregate
+    .true. & ! block_variable
+    ) &
+    ]
+
+end module GwtCncInputModule
diff --git a/src/Model/GroundWaterTransport/gwt1dis1idm.f90 b/src/Model/GroundWaterTransport/gwt1dis1idm.f90
index dda32a6b3a1..9a0330c9461 100644
--- a/src/Model/GroundWaterTransport/gwt1dis1idm.f90
+++ b/src/Model/GroundWaterTransport/gwt1dis1idm.f90
@@ -1,5 +1,6 @@
 ! ** Do Not Modify! MODFLOW 6 system generated file. **
 module GwtDisInputModule
+  use ConstantsModule, only: LENVARNAME
   use InputDefinitionModule, only: InputParamDefinitionType, &
                                    InputBlockDefinitionType
   private
@@ -40,7 +41,8 @@ module GwtDisInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -56,7 +58,8 @@ module GwtDisInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -72,7 +75,8 @@ module GwtDisInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -88,7 +92,8 @@ module GwtDisInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -104,7 +109,8 @@ module GwtDisInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -120,7 +126,8 @@ module GwtDisInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -136,7 +143,8 @@ module GwtDisInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -152,7 +160,8 @@ module GwtDisInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -168,7 +177,8 @@ module GwtDisInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -184,7 +194,8 @@ module GwtDisInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -200,7 +211,8 @@ module GwtDisInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -216,7 +228,8 @@ module GwtDisInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -232,7 +245,8 @@ module GwtDisInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -268,7 +282,8 @@ module GwtDisInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     ) &
     ]
 
diff --git a/src/Model/GroundWaterTransport/gwt1disu1idm.f90 b/src/Model/GroundWaterTransport/gwt1disu1idm.f90
index 1a194976e94..9b552f60f11 100644
--- a/src/Model/GroundWaterTransport/gwt1disu1idm.f90
+++ b/src/Model/GroundWaterTransport/gwt1disu1idm.f90
@@ -1,5 +1,6 @@
 ! ** Do Not Modify! MODFLOW 6 system generated file. **
 module GwtDisuInputModule
+  use ConstantsModule, only: LENVARNAME
   use InputDefinitionModule, only: InputParamDefinitionType, &
                                    InputBlockDefinitionType
   private
@@ -54,7 +55,8 @@ module GwtDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -70,7 +72,8 @@ module GwtDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -86,7 +89,8 @@ module GwtDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -102,7 +106,8 @@ module GwtDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -118,7 +123,8 @@ module GwtDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -134,7 +140,8 @@ module GwtDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -150,7 +157,8 @@ module GwtDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -166,7 +174,8 @@ module GwtDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -182,7 +191,8 @@ module GwtDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -198,7 +208,8 @@ module GwtDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -214,7 +225,8 @@ module GwtDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -230,7 +242,8 @@ module GwtDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -246,7 +259,8 @@ module GwtDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -262,7 +276,8 @@ module GwtDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -278,7 +293,8 @@ module GwtDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -294,7 +310,8 @@ module GwtDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -310,7 +327,8 @@ module GwtDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -326,7 +344,8 @@ module GwtDisuInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -342,7 +361,8 @@ module GwtDisuInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -358,7 +378,8 @@ module GwtDisuInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -374,7 +395,8 @@ module GwtDisuInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -390,7 +412,8 @@ module GwtDisuInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -406,7 +429,8 @@ module GwtDisuInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -422,7 +446,8 @@ module GwtDisuInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -438,7 +463,8 @@ module GwtDisuInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -454,7 +480,8 @@ module GwtDisuInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -470,7 +497,8 @@ module GwtDisuInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -515,10 +543,11 @@ module GwtDisuInputModule
     'VERTICES', & ! fortran variable
     'RECARRAY IV XV YV', & ! type
     'NVERT', & ! shape
-    .true., & ! required
+    .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -531,10 +560,11 @@ module GwtDisuInputModule
     'CELL2D', & ! fortran variable
     'RECARRAY ICELL2D XC YC NCVERT ICVERT', & ! type
     'NODES', & ! shape
-    .true., & ! required
+    .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -573,13 +603,13 @@ module GwtDisuInputModule
     ), &
     InputBlockDefinitionType( &
     'VERTICES', & ! blockname
-    .true., & ! required
+    .false., & ! required
     .true., & ! aggregate
     .false. & ! block_variable
     ), &
     InputBlockDefinitionType( &
     'CELL2D', & ! blockname
-    .true., & ! required
+    .false., & ! required
     .true., & ! aggregate
     .false. & ! block_variable
     ) &
diff --git a/src/Model/GroundWaterTransport/gwt1disv1idm.f90 b/src/Model/GroundWaterTransport/gwt1disv1idm.f90
index 4ed35aca51a..615cc025374 100644
--- a/src/Model/GroundWaterTransport/gwt1disv1idm.f90
+++ b/src/Model/GroundWaterTransport/gwt1disv1idm.f90
@@ -1,5 +1,6 @@
 ! ** Do Not Modify! MODFLOW 6 system generated file. **
 module GwtDisvInputModule
+  use ConstantsModule, only: LENVARNAME
   use InputDefinitionModule, only: InputParamDefinitionType, &
                                    InputBlockDefinitionType
   private
@@ -46,7 +47,8 @@ module GwtDisvInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -62,7 +64,8 @@ module GwtDisvInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -78,7 +81,8 @@ module GwtDisvInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -94,7 +98,8 @@ module GwtDisvInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -110,7 +115,8 @@ module GwtDisvInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -126,7 +132,8 @@ module GwtDisvInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -142,7 +149,8 @@ module GwtDisvInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -158,7 +166,8 @@ module GwtDisvInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -174,7 +183,8 @@ module GwtDisvInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -190,7 +200,8 @@ module GwtDisvInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -206,7 +217,8 @@ module GwtDisvInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -222,7 +234,8 @@ module GwtDisvInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -238,7 +251,8 @@ module GwtDisvInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -254,7 +268,8 @@ module GwtDisvInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -270,7 +285,8 @@ module GwtDisvInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -286,7 +302,8 @@ module GwtDisvInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -302,7 +319,8 @@ module GwtDisvInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -318,7 +336,8 @@ module GwtDisvInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -334,7 +353,8 @@ module GwtDisvInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -374,7 +394,8 @@ module GwtDisvInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -390,7 +411,8 @@ module GwtDisvInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
diff --git a/src/Model/GroundWaterTransport/gwt1dsp1.f90 b/src/Model/GroundWaterTransport/gwt1dsp1.f90
index 50881f867c7..427c7701e86 100644
--- a/src/Model/GroundWaterTransport/gwt1dsp1.f90
+++ b/src/Model/GroundWaterTransport/gwt1dsp1.f90
@@ -4,7 +4,7 @@ module GwtDspModule
   use ConstantsModule, only: DONE, DZERO, DHALF, DPI
   use NumericalPackageModule, only: NumericalPackageType
   use BaseDisModule, only: DisBaseType
-  use GwtFmiModule, only: GwtFmiType
+  use TspFmiModule, only: TspFmiType
   use Xt3dModule, only: Xt3dType, xt3d_cr
   use GwtDspOptionsModule, only: GwtDspOptionsType
   use MatrixBaseModule
@@ -17,7 +17,7 @@ module GwtDspModule
   type, extends(NumericalPackageType) :: GwtDspType
 
     integer(I4B), dimension(:), pointer, contiguous :: ibound => null() ! pointer to GWT model ibound
-    type(GwtFmiType), pointer :: fmi => null() ! pointer to GWT fmi object
+    type(TspFmiType), pointer :: fmi => null() ! pointer to GWT fmi object
     real(DP), dimension(:), pointer, contiguous :: thetam => null() ! pointer to GWT storage porosity (voids per aquifer volume)
     real(DP), dimension(:), pointer, contiguous :: diffc => null() ! molecular diffusion coefficient for each cell
     real(DP), dimension(:), pointer, contiguous :: alh => null() ! longitudinal horizontal dispersivity
@@ -72,13 +72,9 @@ module GwtDspModule
 
 contains
 
+  !> @brief Create a DSP object
+  !<
   subroutine dsp_cr(dspobj, name_model, input_mempath, inunit, iout, fmi)
-! ******************************************************************************
-! dsp_cr -- Create a new DSP object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use KindModule, only: LGP
     use MemoryManagerExtModule, only: mem_set_value
@@ -88,34 +84,27 @@ subroutine dsp_cr(dspobj, name_model, input_mempath, inunit, iout, fmi)
     character(len=*), intent(in) :: input_mempath
     integer(I4B), intent(in) :: inunit
     integer(I4B), intent(in) :: iout
-    type(GwtFmiType), intent(in), target :: fmi
+    type(TspFmiType), intent(in), target :: fmi
     ! -- locals
-    logical(LGP) :: found_fname
     ! -- formats
     character(len=*), parameter :: fmtdsp = &
       "(1x,/1x,'DSP-- DISPERSION PACKAGE, VERSION 1, 1/24/2018', &
       &' INPUT READ FROM MEMPATH: ', A, //)"
-! ------------------------------------------------------------------------------
     !
     ! -- Create the object
     allocate (dspobj)
     !
     ! -- create name and memory path
-    call dspobj%set_names(1, name_model, 'DSP', 'DSP')
+    call dspobj%set_names(1, name_model, 'DSP', 'DSP', input_mempath)
     !
     ! -- Allocate scalars
     call dspobj%allocate_scalars()
     !
     ! -- Set variables
-    dspobj%input_mempath = input_mempath
     dspobj%inunit = inunit
     dspobj%iout = iout
     dspobj%fmi => fmi
     !
-    ! -- set name of input file
-    call mem_set_value(dspobj%input_fname, 'INPUT_FNAME', dspobj%input_mempath, &
-                       found_fname)
-    !
     if (dspobj%inunit > 0) then
       !
       ! -- Print a message identifying the dispersion package.
@@ -128,13 +117,9 @@ subroutine dsp_cr(dspobj, name_model, input_mempath, inunit, iout, fmi)
     return
   end subroutine dsp_cr
 
+  !> @brief Define DSP object
+  !<
   subroutine dsp_df(this, dis, dspOptions)
-! ******************************************************************************
-! dsp_df -- Define
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtDspType) :: this
@@ -142,7 +127,6 @@ subroutine dsp_df(this, dis, dspOptions)
     type(GwtDspOptionsType), optional, intent(in) :: dspOptions !< the optional DSP options, used when not
                                                                 !! creating DSP from file
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- Store pointer to dis
     this%dis => dis
@@ -179,13 +163,11 @@ subroutine dsp_df(this, dis, dspOptions)
     return
   end subroutine dsp_df
 
+  !> @brief Add connections to DSP
+  !!
+  !! Add connections for extended neighbors to the sparse matrix
+  !<
   subroutine dsp_ac(this, moffset, sparse)
-! ******************************************************************************
-! dsp_ac -- Add connections for extended neighbors to the sparse matrix
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SparseModule, only: sparsematrix
     use MemoryManagerModule, only: mem_allocate
@@ -194,7 +176,6 @@ subroutine dsp_ac(this, moffset, sparse)
     integer(I4B), intent(in) :: moffset
     type(sparsematrix), intent(inout) :: sparse
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- Add extended neighbors (neighbors of neighbors)
     if (this%ixt3d > 0) call this%xt3d%xt3d_ac(moffset, sparse)
@@ -203,13 +184,11 @@ subroutine dsp_ac(this, moffset, sparse)
     return
   end subroutine dsp_ac
 
+  !> @brief Map DSP connections
+  !!
+  !! Map connections and construct iax, jax, and idxglox
+  !<
   subroutine dsp_mc(this, moffset, matrix_sln)
-! ******************************************************************************
-! dsp_mc -- Map connections and construct iax, jax, and idxglox
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
@@ -217,7 +196,6 @@ subroutine dsp_mc(this, moffset, matrix_sln)
     integer(I4B), intent(in) :: moffset
     class(MatrixBaseType), pointer :: matrix_sln
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- Call xt3d map connections
     if (this%ixt3d > 0) call this%xt3d%xt3d_mc(moffset, matrix_sln)
@@ -226,13 +204,11 @@ subroutine dsp_mc(this, moffset, matrix_sln)
     return
   end subroutine dsp_mc
 
+  !> @brief Allocate and read method for package
+  !!
+  !!  Method to allocate and read static data for the package.
+  !<
   subroutine dsp_ar(this, ibound, thetam)
-! ******************************************************************************
-! dsp_ar -- Allocate and Read
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtDspType) :: this
@@ -243,7 +219,6 @@ subroutine dsp_ar(this, ibound, thetam)
     character(len=*), parameter :: fmtdsp = &
       "(1x,/1x,'DSP-- DISPERSION PACKAGE, VERSION 1, 1/24/2018', &
       &' INPUT READ FROM UNIT ', i0, //)"
-! ------------------------------------------------------------------------------
     !
     ! -- dsp pointers to arguments that were passed in
     this%ibound => ibound
@@ -253,19 +228,14 @@ subroutine dsp_ar(this, ibound, thetam)
     return
   end subroutine dsp_ar
 
+  !> @brief Advance method for the package
+  !<
   subroutine dsp_ad(this)
-! ******************************************************************************
-! dsp_ad -- Advance
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: kstp, kper
     ! -- dummy
     class(GwtDspType) :: this
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- xt3d
     ! TODO: might consider adding a new mf6 level set pointers method, and
@@ -295,13 +265,11 @@ subroutine dsp_ad(this)
     return
   end subroutine dsp_ad
 
+  !> @brief  Fill coefficient method for package
+  !!
+  !!  Method to calculate and fill coefficients for the package.
+  !<
   subroutine dsp_fc(this, kiter, nodes, nja, matrix_sln, idxglo, rhs, cnew)
-! ******************************************************************************
-! dsp_fc -- Calculate coefficients and fill amat and rhs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtDspType) :: this
@@ -315,7 +283,6 @@ subroutine dsp_fc(this, kiter, nodes, nja, matrix_sln, idxglo, rhs, cnew)
     ! -- local
     integer(I4B) :: n, m, idiag, idiagm, ipos, isympos, isymcon
     real(DP) :: dnm
-! ------------------------------------------------------------------------------
     !
     if (this%ixt3d > 0) then
       call this%xt3d%xt3d_fc(kiter, matrix_sln, idxglo, rhs, cnew)
@@ -348,13 +315,11 @@ subroutine dsp_fc(this, kiter, nodes, nja, matrix_sln, idxglo, rhs, cnew)
     return
   end subroutine dsp_fc
 
+  !> @ brief Calculate flows for package
+  !!
+  !!  Method to calculate dispersion contribution to flowja
+  !<
   subroutine dsp_cq(this, cnew, flowja)
-! ******************************************************************************
-! dsp_cq -- Calculate dispersion contribution to flowja
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtDspType) :: this
@@ -363,7 +328,6 @@ subroutine dsp_cq(this, cnew, flowja)
     ! -- local
     integer(I4B) :: n, m, ipos, isympos
     real(DP) :: dnm
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate dispersion and add to flowja
     if (this%ixt3d > 0) then
@@ -385,20 +349,17 @@ subroutine dsp_cq(this, cnew, flowja)
     return
   end subroutine dsp_cq
 
+  !> @ brief Allocate scalar variables for package
+  !!
+  !!  Method to allocate scalar variables for the package.
+  !<
   subroutine allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     use ConstantsModule, only: DZERO
     ! -- dummy
     class(GwtDspType) :: this
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- allocate scalars in NumericalPackageType
     call this%NumericalPackageType%allocate_scalars()
@@ -441,13 +402,11 @@ subroutine allocate_scalars(this)
     return
   end subroutine allocate_scalars
 
+  !> @ brief Allocate arrays for package
+  !!
+  !!  Method to allocate arrays for the package.
+  !<
   subroutine allocate_arrays(this, nodes)
-! ******************************************************************************
-! allocate_arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     use ConstantsModule, only: DZERO
@@ -455,7 +414,6 @@ subroutine allocate_arrays(this, nodes)
     class(GwtDspType) :: this
     integer(I4B), intent(in) :: nodes
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate
     call mem_allocate(this%alh, nodes, 'ALH', trim(this%memoryPath))
@@ -483,13 +441,11 @@ subroutine allocate_arrays(this, nodes)
     return
   end subroutine allocate_arrays
 
+  !> @ brief Deallocate memory
+  !!
+  !!  Method to deallocate memory for the package.
+  !<
   subroutine dsp_da(this)
-! ******************************************************************************
-! dsp_da
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     use MemoryManagerExtModule, only: memorylist_remove
@@ -497,7 +453,6 @@ subroutine dsp_da(this)
     ! -- dummy
     class(GwtDspType) :: this
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- Deallocate input memory
     call memorylist_remove(this%name_model, 'DSP', idm_context)
@@ -561,15 +516,13 @@ subroutine log_options(this, found)
     write (this%iout, '(4x,a,i0)') 'XT3D formulation [0=INACTIVE, 1=ACTIVE, &
                                    &3=ACTIVE RHS] set to: ', this%ixt3d
     write (this%iout, '(1x,a,/)') 'End Setting DSP Options'
+    ! -- Return
+    return
   end subroutine log_options
 
+  !> @brief Update simulation mempath options
+  !<
   subroutine source_options(this)
-! ******************************************************************************
-! source_options -- update simulation mempath options
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     !use KindModule, only: LGP
     use MemoryManagerExtModule, only: mem_set_value
@@ -578,7 +531,6 @@ subroutine source_options(this)
     class(GwtDspType) :: this
     ! -- locals
     type(GwtDspParamFoundType) :: found
-! ------------------------------------------------------------------------------
     !
     ! -- update defaults with idm sourced values
     call mem_set_value(this%ixt3doff, 'XT3D_OFF', this%input_mempath, &
@@ -636,13 +588,9 @@ subroutine log_griddata(this, found)
 
   end subroutine log_griddata
 
+  !> @brief Update DSP simulation data from input mempath
+  !<
   subroutine source_griddata(this)
-! ******************************************************************************
-! source_griddata -- update dsp simulation data from input mempath
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SimModule, only: count_errors, store_error
     use MemoryManagerModule, only: mem_reallocate, mem_reassignptr
@@ -656,7 +604,6 @@ subroutine source_griddata(this)
     type(GwtDspParamFoundType) :: found
     integer(I4B), dimension(:), pointer, contiguous :: map
     ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- set map
     map => null()
@@ -725,13 +672,9 @@ subroutine source_griddata(this)
     return
   end subroutine source_griddata
 
+  !> @brief Calculate dispersion coefficients
+  !<
   subroutine calcdispellipse(this)
-! ******************************************************************************
-! calcdispellipse -- Calculate dispersion coefficients
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtDspType) :: this
@@ -742,7 +685,6 @@ subroutine calcdispellipse(this)
     real(DP) :: al, at1, at2
     real(DP) :: qzoqsquared
     real(DP) :: dstar
-! ------------------------------------------------------------------------------
     !
     ! -- loop through and calculate dispersion coefficients and angles
     nodes = size(this%d11)
@@ -844,13 +786,9 @@ subroutine calcdispellipse(this)
     return
   end subroutine calcdispellipse
 
+  !> @brief Calculate dispersion coefficients
+  !<
   subroutine calcdispcoef(this)
-! ******************************************************************************
-! calcdispcoef -- Calculate dispersion coefficients
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use GwfNpfModule, only: hyeff_calc
     ! -- dummy
@@ -864,7 +802,6 @@ subroutine calcdispcoef(this)
     real(DP) :: satn, satm, topn, topm, botn, botm
     real(DP) :: hwva, cond, cn, cm, denom
     real(DP) :: anm, amn, thksatn, thksatm, sill_top, sill_bot, tpn, tpm
-! ------------------------------------------------------------------------------
     !
     ! -- set iavgmeth = 1 to use arithmetic averaging for effective dispersion
     iavgmeth = 1
diff --git a/src/Model/GroundWaterTransport/gwt1dsp1idm.f90 b/src/Model/GroundWaterTransport/gwt1dsp1idm.f90
index 0f9e3c29e1d..8b7a4e74332 100644
--- a/src/Model/GroundWaterTransport/gwt1dsp1idm.f90
+++ b/src/Model/GroundWaterTransport/gwt1dsp1idm.f90
@@ -1,5 +1,6 @@
 ! ** Do Not Modify! MODFLOW 6 system generated file. **
 module GwtDspInputModule
+  use ConstantsModule, only: LENVARNAME
   use InputDefinitionModule, only: InputParamDefinitionType, &
                                    InputBlockDefinitionType
   private
@@ -35,7 +36,8 @@ module GwtDspInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -51,7 +53,8 @@ module GwtDspInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -67,7 +70,8 @@ module GwtDspInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -83,7 +87,8 @@ module GwtDspInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -99,7 +104,8 @@ module GwtDspInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -115,7 +121,8 @@ module GwtDspInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -131,7 +138,8 @@ module GwtDspInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -147,7 +155,8 @@ module GwtDspInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .true. & ! layered
+    .true., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -178,7 +187,8 @@ module GwtDspInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     ) &
     ]
 
diff --git a/src/Model/GroundWaterTransport/gwt1fmi1.f90 b/src/Model/GroundWaterTransport/gwt1fmi1.f90
deleted file mode 100644
index cf5680e1868..00000000000
--- a/src/Model/GroundWaterTransport/gwt1fmi1.f90
+++ /dev/null
@@ -1,1570 +0,0 @@
-module GwtFmiModule
-
-  use KindModule, only: DP, I4B
-  use ConstantsModule, only: DONE, DZERO, DHALF, LINELENGTH, LENBUDTXT, &
-                             LENPACKAGENAME
-  use SimModule, only: store_error, store_error_unit
-  use SimVariablesModule, only: errmsg
-  use NumericalPackageModule, only: NumericalPackageType
-  use BaseDisModule, only: DisBaseType
-  use ListModule, only: ListType
-  use BudgetFileReaderModule, only: BudgetFileReaderType
-  use HeadFileReaderModule, only: HeadFileReaderType
-  use PackageBudgetModule, only: PackageBudgetType
-  use BudgetObjectModule, only: BudgetObjectType, budgetobject_cr_bfr
-  use MatrixBaseModule
-
-  implicit none
-  private
-  public :: GwtFmiType
-  public :: fmi_cr
-
-  integer(I4B), parameter :: NBDITEMS = 2
-  character(len=LENBUDTXT), dimension(NBDITEMS) :: budtxt
-  data budtxt/'      FLOW-ERROR', ' FLOW-CORRECTION'/
-
-  type :: DataAdvancedPackageType
-    real(DP), dimension(:), contiguous, pointer :: concpack => null()
-    real(DP), dimension(:), contiguous, pointer :: qmfrommvr => null()
-  end type
-
-  type :: BudObjPtrArray
-    type(BudgetObjectType), pointer :: ptr
-  end type BudObjPtrArray
-
-  type, extends(NumericalPackageType) :: GwtFmiType
-
-    logical, pointer :: flows_from_file => null() !< if .false., then flows come from GWF through GWF-GWT exg
-    integer(I4B), dimension(:), pointer, contiguous :: iatp => null() !< advanced transport package applied to gwfpackages
-    type(ListType), pointer :: gwfbndlist => null() !< list of gwf stress packages
-    integer(I4B), pointer :: iflowsupdated => null() !< flows were updated for this time step
-    integer(I4B), pointer :: iflowerr => null() !< add the flow error correction
-    real(DP), dimension(:), pointer, contiguous :: flowcorrect => null() !< mass flow correction
-    integer(I4B), dimension(:), pointer, contiguous :: ibound => null() !< pointer to GWT ibound
-    real(DP), dimension(:), pointer, contiguous :: gwfflowja => null() !< pointer to the GWF flowja array
-    real(DP), dimension(:, :), pointer, contiguous :: gwfspdis => null() !< pointer to npf specific discharge array
-    real(DP), dimension(:), pointer, contiguous :: gwfhead => null() !< pointer to the GWF head array
-    real(DP), dimension(:), pointer, contiguous :: gwfsat => null() !< pointer to the GWF saturation array
-    integer(I4B), dimension(:), pointer, contiguous :: ibdgwfsat0 => null() !< mark cells with saturation = 0 to exclude from dispersion
-    real(DP), dimension(:), pointer, contiguous :: gwfstrgss => null() !< pointer to flow model QSTOSS
-    real(DP), dimension(:), pointer, contiguous :: gwfstrgsy => null() !< pointer to flow model QSTOSY
-    integer(I4B), pointer :: igwfstrgss => null() !< indicates if gwfstrgss is available
-    integer(I4B), pointer :: igwfstrgsy => null() !< indicates if gwfstrgsy is available
-    integer(I4B), pointer :: iubud => null() !< unit number GWF budget file
-    integer(I4B), pointer :: iuhds => null() !< unit number GWF head file
-    integer(I4B), pointer :: iumvr => null() !< unit number GWF mover budget file
-    integer(I4B), pointer :: nflowpack => null() !< number of GWF flow packages
-    integer(I4B), dimension(:), pointer, contiguous :: igwfmvrterm => null() !< flag to indicate that gwf package is a mover term
-    type(BudgetFileReaderType) :: bfr !< budget file reader
-    type(HeadFileReaderType) :: hfr !< head file reader
-    type(PackageBudgetType), dimension(:), allocatable :: gwfpackages !< used to get flows between a package and gwf
-    type(BudgetObjectType), pointer :: mvrbudobj => null() !< pointer to the mover budget budget object
-    type(DataAdvancedPackageType), &
-      dimension(:), pointer, contiguous :: datp => null()
-    character(len=16), dimension(:), allocatable :: flowpacknamearray !< array of boundary package names (e.g. LAK-1, SFR-3, etc.)
-    type(BudObjPtrArray), dimension(:), allocatable :: aptbudobj !< flow budget objects for the advanced packages
-  contains
-
-    procedure :: fmi_df
-    procedure :: fmi_ar
-    procedure :: fmi_rp
-    procedure :: fmi_ad
-    procedure :: fmi_fc
-    procedure :: fmi_cq
-    procedure :: fmi_bd
-    procedure :: fmi_ot_flow
-    procedure :: fmi_da
-    procedure :: allocate_scalars
-    procedure :: allocate_arrays
-    procedure :: gwfsatold
-    procedure :: read_options
-    procedure :: read_packagedata
-    procedure :: initialize_bfr
-    procedure :: advance_bfr
-    procedure :: finalize_bfr
-    procedure :: initialize_hfr
-    procedure :: advance_hfr
-    procedure :: finalize_hfr
-    procedure :: initialize_gwfterms_from_bfr
-    procedure :: initialize_gwfterms_from_gwfbndlist
-    procedure :: allocate_gwfpackages
-    procedure :: deallocate_gwfpackages
-    procedure :: get_package_index
-    procedure :: set_aptbudobj_pointer
-
-  end type GwtFmiType
-
-contains
-
-  subroutine fmi_cr(fmiobj, name_model, inunit, iout)
-! ******************************************************************************
-! fmi_cr -- Create a new FMI object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- dummy
-    type(GwtFmiType), pointer :: fmiobj
-    character(len=*), intent(in) :: name_model
-    integer(I4B), intent(in) :: inunit
-    integer(I4B), intent(in) :: iout
-! ------------------------------------------------------------------------------
-    !
-    ! -- Create the object
-    allocate (fmiobj)
-    !
-    ! -- create name and memory path
-    call fmiobj%set_names(1, name_model, 'FMI', 'FMI')
-    !
-    ! -- Allocate scalars
-    call fmiobj%allocate_scalars()
-    !
-    ! -- if inunit == 0, then there is no file to read, but it still needs
-    !    to be active in order to manage pointers to gwf model
-    !if (inunit == 0) inunit = 1
-    !
-    ! -- Set variables
-    fmiobj%inunit = inunit
-    fmiobj%iout = iout
-    !
-    ! -- Initialize block parser
-    call fmiobj%parser%Initialize(fmiobj%inunit, fmiobj%iout)
-    !
-    ! -- Return
-    return
-  end subroutine fmi_cr
-
-  subroutine fmi_df(this, dis, inssm)
-! ******************************************************************************
-! fmi_df -- Define
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use SimModule, only: store_error
-    ! -- dummy
-    class(GwtFmiType) :: this
-    class(DisBaseType), pointer, intent(in) :: dis
-    integer(I4B), intent(in) :: inssm
-    ! -- local
-    ! -- formats
-    character(len=*), parameter :: fmtfmi = &
-      "(1x,/1x,'FMI -- FLOW MODEL INTERFACE, VERSION 1, 8/29/2017', &
-      &' INPUT READ FROM UNIT ', i0, //)"
-    character(len=*), parameter :: fmtfmi0 = &
-      &"(1x,/1x,'FMI -- FLOW MODEL INTERFACE, VERSION 1, 8/29/2017')"
-! ------------------------------------------------------------------------------
-    !
-    ! --print a message identifying the FMI package.
-    if (this%iout > 0) then
-      if (this%inunit /= 0) then
-        write (this%iout, fmtfmi) this%inunit
-      else
-        write (this%iout, fmtfmi0)
-        if (this%flows_from_file) then
-          write (this%iout, '(a)') '  FLOWS ARE ASSUMED TO BE ZERO.'
-        else
-          write (this%iout, '(a)') '  FLOWS PROVIDED BY A GWF MODEL IN THIS &
-            &SIMULATION'
-        end if
-      end if
-    end if
-    !
-    ! -- store pointers to arguments that were passed in
-    this%dis => dis
-    !
-    ! -- Read fmi options
-    if (this%inunit /= 0) then
-      call this%read_options()
-    end if
-    !
-    ! -- Read packagedata options
-    if (this%inunit /= 0 .and. this%flows_from_file) then
-      call this%read_packagedata()
-      call this%initialize_gwfterms_from_bfr()
-    end if
-    !
-    ! -- If GWF-GWT exchange is active, then setup gwfterms from bndlist
-    if (.not. this%flows_from_file) then
-      call this%initialize_gwfterms_from_gwfbndlist()
-    end if
-    !
-    ! -- Make sure that ssm is on if there are any boundary packages
-    if (inssm == 0) then
-      if (this%nflowpack > 0) then
-        call store_error('Flow model has boundary packages, but there &
-          &is no SSM package.  The SSM package must be activated.', &
-          terminate=.TRUE.)
-      end if
-    end if
-    !
-    ! -- Return
-    return
-  end subroutine fmi_df
-
-  subroutine fmi_ar(this, ibound)
-! ******************************************************************************
-! fmi_ar -- Allocate and Read
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use SimModule, only: store_error
-    ! -- dummy
-    class(GwtFmiType) :: this
-    integer(I4B), dimension(:), pointer, contiguous :: ibound
-    ! -- local
-    ! -- formats
-! ------------------------------------------------------------------------------
-    !
-    ! -- store pointers to arguments that were passed in
-    this%ibound => ibound
-    !
-    ! -- Allocate arrays
-    call this%allocate_arrays(this%dis%nodes)
-    !
-    ! -- Return
-    return
-  end subroutine fmi_ar
-
-  subroutine fmi_rp(this, inmvr)
-! ******************************************************************************
-! fmi_rp -- Read and prepare
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use TdisModule, only: kper, kstp
-    ! -- dummy
-    class(GwtFmiType) :: this
-    integer(I4B), intent(in) :: inmvr
-    ! -- local
-    ! -- formats
-! ------------------------------------------------------------------------------
-    !
-    ! --Check to make sure MVT Package is active if mvr flows are available.
-    !   This cannot be checked until RP because exchange doesn't set a pointer
-    !   to mvrbudobj until exg_ar().
-    if (kper * kstp == 1) then
-      if (associated(this%mvrbudobj) .and. inmvr == 0) then
-        write (errmsg, '(a)') 'GWF water mover is active but the GWT MVT &
-          &package has not been specified.  activate GWT MVT package.'
-        call store_error(errmsg, terminate=.TRUE.)
-      end if
-      if (.not. associated(this%mvrbudobj) .and. inmvr > 0) then
-        write (errmsg, '(a)') 'GWF water mover terms are not available &
-          &but the GWT MVT package has been activated.  Activate GWF-GWT &
-          &exchange or specify GWFMOVER in FMI PACKAGEDATA.'
-        call store_error(errmsg, terminate=.TRUE.)
-      end if
-    end if
-    !
-    ! -- Return
-    return
-  end subroutine fmi_rp
-
-  subroutine fmi_ad(this, cnew)
-! ******************************************************************************
-! fmi_ad -- advance
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use ConstantsModule, only: DHDRY
-    ! -- dummy
-    class(GwtFmiType) :: this
-    real(DP), intent(inout), dimension(:) :: cnew
-    ! -- local
-    integer(I4B) :: n
-    integer(I4B) :: m
-    integer(I4B) :: ipos
-    real(DP) :: crewet, tflow, flownm
-    character(len=15) :: nodestr
-    character(len=*), parameter :: fmtdry = &
-     &"(/1X,'WARNING: DRY CELL ENCOUNTERED AT ',a,';  RESET AS INACTIVE &
-     &WITH DRY CONCENTRATION = ', G13.5)"
-    character(len=*), parameter :: fmtrewet = &
-     &"(/1X,'DRY CELL REACTIVATED AT ', a,&
-     &' WITH STARTING CONCENTRATION =',G13.5)"
-! ------------------------------------------------------------------------------
-    !
-    ! -- Set flag to indicated that flows are being updated.  For the case where
-    !    flows may be reused (only when flows are read from a file) then set
-    !    the flag to zero to indicated that flows were not updated
-    this%iflowsupdated = 1
-    !
-    ! -- If reading flows from a budget file, read the next set of records
-    if (this%iubud /= 0) then
-      call this%advance_bfr()
-    end if
-    !
-    ! -- If reading heads from a head file, read the next set of records
-    if (this%iuhds /= 0) then
-      call this%advance_hfr()
-    end if
-    !
-    ! -- If mover flows are being read from file, read the next set of records
-    if (this%iumvr /= 0) then
-      call this%mvrbudobj%bfr_advance(this%dis, this%iout)
-    end if
-    !
-    ! -- If advanced package flows are being read from file, read the next set of records
-    if (this%flows_from_file .and. this%inunit /= 0) then
-      do n = 1, size(this%aptbudobj)
-        call this%aptbudobj(n)%ptr%bfr_advance(this%dis, this%iout)
-      end do
-    end if
-    !
-    ! -- if flow cell is dry, then set gwt%ibound = 0 and conc to dry
-    do n = 1, this%dis%nodes
-      !
-      ! -- Calculate the ibound-like array that has 0 if saturation
-      !    is zero and 1 otherwise
-      if (this%gwfsat(n) > DZERO) then
-        this%ibdgwfsat0(n) = 1
-      else
-        this%ibdgwfsat0(n) = 0
-      end if
-      !
-      ! -- Check if active transport cell is inactive for flow
-      if (this%ibound(n) > 0) then
-        if (this%gwfhead(n) == DHDRY) then
-          ! -- transport cell should be made inactive
-          this%ibound(n) = 0
-          cnew(n) = DHDRY
-          call this%dis%noder_to_string(n, nodestr)
-          write (this%iout, fmtdry) trim(nodestr), DHDRY
-        end if
-      end if
-      !
-      ! -- Convert dry transport cell to active if flow has rewet
-      if (cnew(n) == DHDRY) then
-        if (this%gwfhead(n) /= DHDRY) then
-          !
-          ! -- obtain weighted concentration
-          crewet = DZERO
-          tflow = DZERO
-          do ipos = this%dis%con%ia(n) + 1, this%dis%con%ia(n + 1) - 1
-            m = this%dis%con%ja(ipos)
-            flownm = this%gwfflowja(ipos)
-            if (flownm > 0) then
-              if (this%ibound(m) /= 0) then
-                crewet = crewet + cnew(m) * flownm
-                tflow = tflow + this%gwfflowja(ipos)
-              end if
-            end if
-          end do
-          if (tflow > DZERO) then
-            crewet = crewet / tflow
-          else
-            crewet = DZERO
-          end if
-          !
-          ! -- cell is now wet
-          this%ibound(n) = 1
-          cnew(n) = crewet
-          call this%dis%noder_to_string(n, nodestr)
-          write (this%iout, fmtrewet) trim(nodestr), crewet
-        end if
-      end if
-    end do
-    !
-    ! -- Return
-    return
-  end subroutine fmi_ad
-
-  subroutine fmi_fc(this, nodes, cold, nja, matrix_sln, idxglo, rhs)
-! ******************************************************************************
-! fmi_fc -- Calculate coefficients and fill matrix and rhs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    !use BndModule,              only: BndType, GetBndFromList
-    ! -- dummy
-    class(GwtFmiType) :: this
-    integer, intent(in) :: nodes
-    real(DP), intent(in), dimension(nodes) :: cold
-    integer(I4B), intent(in) :: nja
-    class(MatrixBaseType), pointer :: matrix_sln
-    integer(I4B), intent(in), dimension(nja) :: idxglo
-    real(DP), intent(inout), dimension(nodes) :: rhs
-    ! -- local
-    integer(I4B) :: n, idiag, idiag_sln
-! ------------------------------------------------------------------------------
-    !
-    ! -- Calculate the flow imbalance error and make a correction for it
-    if (this%iflowerr /= 0) then
-      !
-      ! -- Correct the transport solution for the flow imbalance by adding
-      !    the flow residual to the diagonal
-      do n = 1, nodes
-        idiag = this%dis%con%ia(n)
-        idiag_sln = idxglo(idiag)
-        call matrix_sln%add_value_pos(idiag_sln, -this%gwfflowja(idiag))
-      end do
-    end if
-    !
-    ! -- Return
-    return
-  end subroutine fmi_fc
-
-  subroutine fmi_cq(this, cnew, flowja)
-! ******************************************************************************
-! fmi_cq -- Calculate flow correction
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    ! -- dummy
-    class(GwtFmiType) :: this
-    real(DP), intent(in), dimension(:) :: cnew
-    real(DP), dimension(:), contiguous, intent(inout) :: flowja
-    ! -- local
-    integer(I4B) :: n
-    integer(I4B) :: idiag
-    real(DP) :: rate
-! ------------------------------------------------------------------------------
-    !
-    ! -- If not adding flow error correction, return
-    if (this%iflowerr /= 0) then
-      !
-      ! -- Accumulate the flow correction term
-      do n = 1, this%dis%nodes
-        rate = DZERO
-        idiag = this%dis%con%ia(n)
-        if (this%ibound(n) > 0) then
-          rate = -this%gwfflowja(idiag) * cnew(n)
-        end if
-        this%flowcorrect(n) = rate
-        flowja(idiag) = flowja(idiag) + rate
-      end do
-    end if
-    !
-    ! -- Return
-    return
-  end subroutine fmi_cq
-
-  subroutine fmi_bd(this, isuppress_output, model_budget)
-! ******************************************************************************
-! mst_bd -- Calculate budget terms
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use TdisModule, only: delt
-    use BudgetModule, only: BudgetType, rate_accumulator
-    ! -- dummy
-    class(GwtFmiType) :: this
-    integer(I4B), intent(in) :: isuppress_output
-    type(BudgetType), intent(inout) :: model_budget
-    ! -- local
-    real(DP) :: rin
-    real(DP) :: rout
-! ------------------------------------------------------------------------------
-    !
-    ! -- flow correction
-    if (this%iflowerr /= 0) then
-      call rate_accumulator(this%flowcorrect, rin, rout)
-      call model_budget%addentry(rin, rout, delt, budtxt(2), isuppress_output)
-    end if
-    !
-    ! -- Return
-    return
-  end subroutine fmi_bd
-
-  subroutine fmi_ot_flow(this, icbcfl, icbcun)
-! ******************************************************************************
-! fmi_ot_flow -- Save budget terms
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- dummy
-    class(GwtFmiType) :: this
-    integer(I4B), intent(in) :: icbcfl
-    integer(I4B), intent(in) :: icbcun
-    ! -- local
-    integer(I4B) :: ibinun
-    integer(I4B) :: iprint, nvaluesp, nwidthp
-    character(len=1) :: cdatafmp = ' ', editdesc = ' '
-    real(DP) :: dinact
-! ------------------------------------------------------------------------------
-    !
-    ! -- Set unit number for binary output
-    if (this%ipakcb < 0) then
-      ibinun = icbcun
-    elseif (this%ipakcb == 0) then
-      ibinun = 0
-    else
-      ibinun = this%ipakcb
-    end if
-    if (icbcfl == 0) ibinun = 0
-    !
-    ! -- Do not save flow corrections if not active
-    if (this%iflowerr == 0) ibinun = 0
-    !
-    ! -- Record the storage rates if requested
-    if (ibinun /= 0) then
-      iprint = 0
-      dinact = DZERO
-      !
-      ! -- flow correction
-      call this%dis%record_array(this%flowcorrect, this%iout, iprint, -ibinun, &
-                                 budtxt(2), cdatafmp, nvaluesp, &
-                                 nwidthp, editdesc, dinact)
-    end if
-    !
-    ! -- Return
-    return
-  end subroutine fmi_ot_flow
-
-  subroutine fmi_da(this)
-! ******************************************************************************
-! fmi_da -- Deallocate variables
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_deallocate
-    ! -- dummy
-    class(GwtFmiType) :: this
-! ------------------------------------------------------------------------------
-    ! -- todo: finalize hfr and bfr either here or in a finalize routine
-    !
-    ! -- deallocate any memory stored with gwfpackages
-    call this%deallocate_gwfpackages()
-    !
-    ! -- deallocate fmi arrays
-    if (associated(this%datp)) then
-      deallocate (this%datp)
-      deallocate (this%gwfpackages)
-      deallocate (this%flowpacknamearray)
-      call mem_deallocate(this%iatp)
-      call mem_deallocate(this%igwfmvrterm)
-    end if
-
-    deallocate (this%aptbudobj)
-    call mem_deallocate(this%flowcorrect)
-    call mem_deallocate(this%ibdgwfsat0)
-    if (this%flows_from_file) then
-      call mem_deallocate(this%gwfstrgss)
-      call mem_deallocate(this%gwfstrgsy)
-    end if
-    !
-    ! -- special treatment, these could be from mem_checkin
-    call mem_deallocate(this%gwfhead, 'GWFHEAD', this%memoryPath)
-    call mem_deallocate(this%gwfsat, 'GWFSAT', this%memoryPath)
-    call mem_deallocate(this%gwfspdis, 'GWFSPDIS', this%memoryPath)
-    call mem_deallocate(this%gwfflowja, 'GWFFLOWJA', this%memoryPath)
-    !
-    ! -- deallocate scalars
-    call mem_deallocate(this%flows_from_file)
-    call mem_deallocate(this%iflowsupdated)
-    call mem_deallocate(this%iflowerr)
-    call mem_deallocate(this%igwfstrgss)
-    call mem_deallocate(this%igwfstrgsy)
-    call mem_deallocate(this%iubud)
-    call mem_deallocate(this%iuhds)
-    call mem_deallocate(this%iumvr)
-    call mem_deallocate(this%nflowpack)
-    !
-    ! -- deallocate parent
-    call this%NumericalPackageType%da()
-    !
-    ! -- Return
-    return
-  end subroutine fmi_da
-
-  subroutine allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_allocate, mem_setptr
-    ! -- dummy
-    class(GwtFmiType) :: this
-    ! -- local
-! ------------------------------------------------------------------------------
-    !
-    ! -- allocate scalars in NumericalPackageType
-    call this%NumericalPackageType%allocate_scalars()
-    !
-    ! -- Allocate
-    call mem_allocate(this%flows_from_file, 'FLOWS_FROM_FILE', this%memoryPath)
-    call mem_allocate(this%iflowsupdated, 'IFLOWSUPDATED', this%memoryPath)
-    call mem_allocate(this%iflowerr, 'IFLOWERR', this%memoryPath)
-    call mem_allocate(this%igwfstrgss, 'IGWFSTRGSS', this%memoryPath)
-    call mem_allocate(this%igwfstrgsy, 'IGWFSTRGSY', this%memoryPath)
-    call mem_allocate(this%iubud, 'IUBUD', this%memoryPath)
-    call mem_allocate(this%iuhds, 'IUHDS', this%memoryPath)
-    call mem_allocate(this%iumvr, 'IUMVR', this%memoryPath)
-    call mem_allocate(this%nflowpack, 'NFLOWPACK', this%memoryPath)
-    !
-    ! -- Although not a scalar, allocate the advanced package transport
-    !    budget object to zero so that it can be dynamically resized later
-    allocate (this%aptbudobj(0))
-    !
-    ! -- Initialize
-    this%flows_from_file = .true.
-    this%iflowsupdated = 1
-    this%iflowerr = 0
-    this%igwfstrgss = 0
-    this%igwfstrgsy = 0
-    this%iubud = 0
-    this%iuhds = 0
-    this%iumvr = 0
-    this%nflowpack = 0
-    !
-    ! -- Return
-    return
-  end subroutine allocate_scalars
-
-  subroutine allocate_arrays(this, nodes)
-! ******************************************************************************
-! allocate_arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use MemoryManagerModule, only: mem_allocate
-    !modules
-    use ConstantsModule, only: DZERO
-    ! -- dummy
-    class(GwtFmiType) :: this
-    integer(I4B), intent(in) :: nodes
-    ! -- local
-    integer(I4B) :: n
-! ------------------------------------------------------------------------------
-    !
-    ! -- Allocate variables needed for all cases
-    if (this%iflowerr == 0) then
-      call mem_allocate(this%flowcorrect, 1, 'FLOWCORRECT', this%memoryPath)
-    else
-      call mem_allocate(this%flowcorrect, nodes, 'FLOWCORRECT', this%memoryPath)
-    end if
-    do n = 1, size(this%flowcorrect)
-      this%flowcorrect(n) = DZERO
-    end do
-    !
-    ! -- Allocate ibdgwfsat0, which is an indicator array marking cells with
-    !    saturation greater than 0.0 with a value of 1
-    call mem_allocate(this%ibdgwfsat0, nodes, 'IBDGWFSAT0', this%memoryPath)
-    do n = 1, nodes
-      this%ibdgwfsat0(n) = 1
-    end do
-    !
-    ! -- Allocate differently depending on whether or not flows are
-    !    being read from a file.
-    if (this%flows_from_file) then
-      call mem_allocate(this%gwfflowja, this%dis%con%nja, 'GWFFLOWJA', &
-                        this%memoryPath)
-      call mem_allocate(this%gwfsat, nodes, 'GWFSAT', this%memoryPath)
-      call mem_allocate(this%gwfhead, nodes, 'GWFHEAD', this%memoryPath)
-      call mem_allocate(this%gwfspdis, 3, nodes, 'GWFSPDIS', this%memoryPath)
-      do n = 1, nodes
-        this%gwfsat(n) = DONE
-        this%gwfhead(n) = DZERO
-        this%gwfspdis(:, n) = DZERO
-      end do
-      do n = 1, size(this%gwfflowja)
-        this%gwfflowja(n) = DZERO
-      end do
-      !
-      ! -- allocate and initialize storage arrays
-      if (this%igwfstrgss == 0) then
-        call mem_allocate(this%gwfstrgss, 1, 'GWFSTRGSS', this%memoryPath)
-      else
-        call mem_allocate(this%gwfstrgss, nodes, 'GWFSTRGSS', this%memoryPath)
-      end if
-      if (this%igwfstrgsy == 0) then
-        call mem_allocate(this%gwfstrgsy, 1, 'GWFSTRGSY', this%memoryPath)
-      else
-        call mem_allocate(this%gwfstrgsy, nodes, 'GWFSTRGSY', this%memoryPath)
-      end if
-      do n = 1, size(this%gwfstrgss)
-        this%gwfstrgss(n) = DZERO
-      end do
-      do n = 1, size(this%gwfstrgsy)
-        this%gwfstrgsy(n) = DZERO
-      end do
-      !
-      ! -- If there is no fmi package, then there are no flows at all or a
-      !    connected GWF model, so allocate gwfpackages to zero
-      if (this%inunit == 0) call this%allocate_gwfpackages(this%nflowpack)
-    end if
-    !
-    ! -- Return
-    return
-  end subroutine allocate_arrays
-
-  function gwfsatold(this, n, delt) result(satold)
-! ******************************************************************************
-! gwfsatold -- calculate the groundwater cell head saturation for the end of
-!   the last time step
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    ! -- dummy
-    class(GwtFmiType) :: this
-    integer(I4B), intent(in) :: n
-    real(DP), intent(in) :: delt
-    ! -- result
-    real(DP) :: satold
-    ! -- local
-    real(DP) :: vcell
-    real(DP) :: vnew
-    real(DP) :: vold
-! ------------------------------------------------------------------------------
-    !
-    ! -- calculate the value
-    vcell = this%dis%area(n) * (this%dis%top(n) - this%dis%bot(n))
-    vnew = vcell * this%gwfsat(n)
-    vold = vnew
-    if (this%igwfstrgss /= 0) vold = vold + this%gwfstrgss(n) * delt
-    if (this%igwfstrgsy /= 0) vold = vold + this%gwfstrgsy(n) * delt
-    satold = vold / vcell
-    !
-    ! -- Return
-    return
-  end function gwfsatold
-
-  subroutine read_options(this)
-! ******************************************************************************
-! read_options -- Read Options
-! Subroutine: (1) read options from input file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use ConstantsModule, only: LINELENGTH, DEM6
-    use InputOutputModule, only: getunit, openfile, urdaux
-    use SimModule, only: store_error, store_error_unit
-    ! -- dummy
-    class(GwtFmiType) :: this
-    ! -- local
-    character(len=LINELENGTH) :: keyword
-    integer(I4B) :: ierr
-    logical :: isfound, endOfBlock
-    character(len=*), parameter :: fmtisvflow = &
-      "(4x,'CELL-BY-CELL FLOW INFORMATION WILL BE SAVED TO BINARY FILE &
-      &WHENEVER ICBCFL IS NOT ZERO AND FLOW IMBALANCE CORRECTION ACTIVE.')"
-    character(len=*), parameter :: fmtifc = &
-      &"(4x,'MASS WILL BE ADDED OR REMOVED TO COMPENSATE FOR FLOW IMBALANCE.')"
-! ------------------------------------------------------------------------------
-    !
-    ! -- get options block
-    call this%parser%GetBlock('OPTIONS', isfound, ierr, blockRequired=.false., &
-                              supportOpenClose=.true.)
-    !
-    ! -- parse options block if detected
-    if (isfound) then
-      write (this%iout, '(1x,a)') 'PROCESSING FMI OPTIONS'
-      do
-        call this%parser%GetNextLine(endOfBlock)
-        if (endOfBlock) exit
-        call this%parser%GetStringCaps(keyword)
-        select case (keyword)
-        case ('SAVE_FLOWS')
-          this%ipakcb = -1
-          write (this%iout, fmtisvflow)
-        case ('FLOW_IMBALANCE_CORRECTION')
-          write (this%iout, fmtifc)
-          this%iflowerr = 1
-        case default
-          write (errmsg, '(a,a)') 'Unknown FMI option: ', &
-            trim(keyword)
-          call store_error(errmsg)
-          call this%parser%StoreErrorUnit()
-        end select
-      end do
-      write (this%iout, '(1x,a)') 'END OF FMI OPTIONS'
-    end if
-    !
-    ! -- return
-    return
-  end subroutine read_options
-
-  subroutine read_packagedata(this)
-! ******************************************************************************
-! read_packagedata -- Read PACKAGEDATA block
-! Subroutine: (1) read packagedata block from input file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use OpenSpecModule, only: ACCESS, FORM
-    use ConstantsModule, only: LINELENGTH, DEM6, LENPACKAGENAME
-    use InputOutputModule, only: getunit, openfile, urdaux
-    use SimModule, only: store_error, store_error_unit
-    ! -- dummy
-    class(GwtFmiType) :: this
-    ! -- local
-    type(BudgetObjectType), pointer :: budobjptr
-    character(len=LINELENGTH) :: keyword, fname
-    character(len=LENPACKAGENAME) :: pname
-    integer(I4B) :: i
-    integer(I4B) :: ierr
-    integer(I4B) :: inunit
-    integer(I4B) :: iapt
-    logical :: isfound, endOfBlock
-    logical :: blockrequired
-    logical :: exist
-    type(BudObjPtrArray), dimension(:), allocatable :: tmpbudobj
-! ------------------------------------------------------------------------------
-    !
-    ! -- initialize
-    iapt = 0
-    blockrequired = .true.
-    !
-    ! -- get options block
-    call this%parser%GetBlock('PACKAGEDATA', isfound, ierr, &
-                              blockRequired=blockRequired, &
-                              supportOpenClose=.true.)
-    !
-    ! -- parse options block if detected
-    if (isfound) then
-      write (this%iout, '(1x,a)') 'PROCESSING FMI PACKAGEDATA'
-      do
-        call this%parser%GetNextLine(endOfBlock)
-        if (endOfBlock) exit
-        call this%parser%GetStringCaps(keyword)
-        select case (keyword)
-        case ('GWFBUDGET')
-          call this%parser%GetStringCaps(keyword)
-          if (keyword /= 'FILEIN') then
-            call store_error('GWFBUDGET keyword must be followed by '// &
-                             '"FILEIN" then by filename.')
-            call this%parser%StoreErrorUnit()
-          end if
-          call this%parser%GetString(fname)
-          inunit = getunit()
-          inquire (file=trim(fname), exist=exist)
-          if (.not. exist) then
-            call store_error('Could not find file '//trim(fname))
-            call this%parser%StoreErrorUnit()
-          end if
-          call openfile(inunit, this%iout, fname, 'DATA(BINARY)', FORM, &
-                        ACCESS, 'UNKNOWN')
-          this%iubud = inunit
-          call this%initialize_bfr()
-        case ('GWFHEAD')
-          call this%parser%GetStringCaps(keyword)
-          if (keyword /= 'FILEIN') then
-            call store_error('GWFHEAD keyword must be followed by '// &
-                             '"FILEIN" then by filename.')
-            call this%parser%StoreErrorUnit()
-          end if
-          call this%parser%GetString(fname)
-          inquire (file=trim(fname), exist=exist)
-          if (.not. exist) then
-            call store_error('Could not find file '//trim(fname))
-            call this%parser%StoreErrorUnit()
-          end if
-          inunit = getunit()
-          call openfile(inunit, this%iout, fname, 'DATA(BINARY)', FORM, &
-                        ACCESS, 'UNKNOWN')
-          this%iuhds = inunit
-          call this%initialize_hfr()
-        case ('GWFMOVER')
-          call this%parser%GetStringCaps(keyword)
-          if (keyword /= 'FILEIN') then
-            call store_error('GWFMOVER keyword must be followed by '// &
-                             '"FILEIN" then by filename.')
-            call this%parser%StoreErrorUnit()
-          end if
-          call this%parser%GetString(fname)
-          inunit = getunit()
-          call openfile(inunit, this%iout, fname, 'DATA(BINARY)', FORM, &
-                        ACCESS, 'UNKNOWN')
-          this%iumvr = inunit
-          call budgetobject_cr_bfr(this%mvrbudobj, 'MVT', this%iumvr, &
-                                   this%iout)
-          call this%mvrbudobj%fill_from_bfr(this%dis, this%iout)
-        case default
-          !
-          ! --expand the size of aptbudobj, which stores a pointer to the budobj
-          allocate (tmpbudobj(iapt))
-          do i = 1, size(this%aptbudobj)
-            tmpbudobj(i)%ptr => this%aptbudobj(i)%ptr
-          end do
-          deallocate (this%aptbudobj)
-          allocate (this%aptbudobj(iapt + 1))
-          do i = 1, size(tmpbudobj)
-            this%aptbudobj(i)%ptr => tmpbudobj(i)%ptr
-          end do
-          deallocate (tmpbudobj)
-          !
-          ! -- Open the budget file and start filling it
-          iapt = iapt + 1
-          pname = keyword(1:LENPACKAGENAME)
-          call this%parser%GetStringCaps(keyword)
-          if (keyword /= 'FILEIN') then
-            call store_error('Package name must be followed by '// &
-                             '"FILEIN" then by filename.')
-            call this%parser%StoreErrorUnit()
-          end if
-          call this%parser%GetString(fname)
-          inunit = getunit()
-          call openfile(inunit, this%iout, fname, 'DATA(BINARY)', FORM, &
-                        ACCESS, 'UNKNOWN')
-          call budgetobject_cr_bfr(budobjptr, pname, inunit, &
-                                   this%iout, colconv2=['GWF             '])
-          call budobjptr%fill_from_bfr(this%dis, this%iout)
-          this%aptbudobj(iapt)%ptr => budobjptr
-        end select
-      end do
-      write (this%iout, '(1x,a)') 'END OF FMI PACKAGEDATA'
-    end if
-    !
-    ! -- return
-    return
-  end subroutine read_packagedata
-
-  subroutine set_aptbudobj_pointer(this, name, budobjptr)
-! ******************************************************************************
-! set_aptbudobj_pointer -- an advanced transport can pass in a name and a
-!   pointer budget object, and this routine will look through the budget
-!   objects managed by FMI and point to the one with the same name, such as
-!   LAK-1, SFR-1, etc.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    class(GwtFmiType) :: this
-    ! -- dumm
-    character(len=*), intent(in) :: name
-    type(BudgetObjectType), pointer :: budobjptr
-    ! -- local
-    integer(I4B) :: i
-! ------------------------------------------------------------------------------
-    !
-    ! -- find and set the pointer
-    do i = 1, size(this%aptbudobj)
-      if (this%aptbudobj(i)%ptr%name == name) then
-        budobjptr => this%aptbudobj(i)%ptr
-        exit
-      end if
-    end do
-    !
-    ! -- return
-    return
-  end subroutine set_aptbudobj_pointer
-
-  subroutine initialize_bfr(this)
-! ******************************************************************************
-! initialize_bfr -- initalize the budget file reader
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    class(GwtFmiType) :: this
-    ! -- dummy
-    integer(I4B) :: ncrbud
-! ------------------------------------------------------------------------------
-    !
-    ! -- Initialize the budget file reader
-    call this%bfr%initialize(this%iubud, this%iout, ncrbud)
-    !
-    ! -- todo: need to run through the budget terms
-    !    and do some checking
-  end subroutine initialize_bfr
-
-  subroutine advance_bfr(this)
-! ******************************************************************************
-! advance_bfr -- advance the budget file reader by reading the next chunk
-!   of information for the current time step and stress period
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use TdisModule, only: kstp, kper
-    ! -- dummy
-    class(GwtFmiType) :: this
-    ! -- local
-    logical :: success
-    integer(I4B) :: n
-    integer(I4B) :: ipos
-    integer(I4B) :: nu, nr
-    integer(I4B) :: ip, i
-    logical :: readnext
-    ! -- format
-    character(len=*), parameter :: fmtkstpkper = &
-      &"(1x,/1x,'FMI READING BUDGET TERMS FOR KSTP ', i0, ' KPER ', i0)"
-    character(len=*), parameter :: fmtbudkstpkper = &
-      "(1x,/1x, 'FMI SETTING BUDGET TERMS FOR KSTP ', i0, ' AND KPER ', &
-      &i0, ' TO BUDGET FILE TERMS FROM KSTP ', i0, ' AND KPER ', i0)"
-! ------------------------------------------------------------------------------
-    !
-    ! -- If the latest record read from the budget file is from a stress
-    ! -- period with only one time step, reuse that record (do not read a
-    ! -- new record) if the GWT model is still in that same stress period,
-    ! -- or if that record is the last one in the budget file.
-    readnext = .true.
-    if (kstp * kper > 1) then
-      if (this%bfr%kstp == 1) then
-        if (this%bfr%kpernext == kper + 1) then
-          readnext = .false.
-        else if (this%bfr%endoffile) then
-          readnext = .false.
-        end if
-      else if (this%bfr%endoffile) then
-        write (errmsg, '(a)') 'Reached end of GWF budget &
-          &file before reading sufficient budget information for this &
-          &GWT simulation.'
-        call store_error(errmsg)
-        call store_error_unit(this%iubud)
-      end if
-    end if
-    !
-    ! -- Read the next record
-    if (readnext) then
-      !
-      ! -- Write the current time step and stress period
-      write (this%iout, fmtkstpkper) kstp, kper
-      !
-      ! -- loop through the budget terms for this stress period
-      !    i is the counter for gwf flow packages
-      ip = 1
-      do n = 1, this%bfr%nbudterms
-        call this%bfr%read_record(success, this%iout)
-        if (.not. success) then
-          write (errmsg, '(a)') 'GWF budget read not successful'
-          call store_error(errmsg)
-          call store_error_unit(this%iubud)
-        end if
-        !
-        ! -- Ensure kper is same between model and budget file
-        if (kper /= this%bfr%kper) then
-          write (errmsg, '(a)') 'Period number in budget file &
-            &does not match period number in transport model.  If there &
-            &is more than one time step in the budget file for a given stress &
-            &period, budget file time steps must match GWT model time steps &
-            &one-for-one in that stress period.'
-          call store_error(errmsg)
-          call store_error_unit(this%iubud)
-        end if
-        !
-        ! -- if budget file kstp > 1, then kstp must match
-        if (this%bfr%kstp > 1 .and. (kstp /= this%bfr%kstp)) then
-          write (errmsg, '(a)') 'Time step number in budget file &
-            &does not match time step number in transport model.  If there &
-            &is more than one time step in the budget file for a given stress &
-            &period, budget file time steps must match gwt model time steps &
-            &one-for-one in that stress period.'
-          call store_error(errmsg)
-          call store_error_unit(this%iubud)
-        end if
-        !
-        ! -- parse based on the type of data, and compress all user node
-        !    numbers into reduced node numbers
-        select case (trim(adjustl(this%bfr%budtxt)))
-        case ('FLOW-JA-FACE')
-          !
-          ! -- bfr%flowja contains only reduced connections so there is
-          !    a one-to-one match with this%gwfflowja
-          do ipos = 1, size(this%bfr%flowja)
-            this%gwfflowja(ipos) = this%bfr%flowja(ipos)
-          end do
-        case ('DATA-SPDIS')
-          do i = 1, this%bfr%nlist
-            nu = this%bfr%nodesrc(i)
-            nr = this%dis%get_nodenumber(nu, 0)
-            if (nr <= 0) cycle
-            this%gwfspdis(1, nr) = this%bfr%auxvar(1, i)
-            this%gwfspdis(2, nr) = this%bfr%auxvar(2, i)
-            this%gwfspdis(3, nr) = this%bfr%auxvar(3, i)
-          end do
-        case ('DATA-SAT')
-          do i = 1, this%bfr%nlist
-            nu = this%bfr%nodesrc(i)
-            nr = this%dis%get_nodenumber(nu, 0)
-            if (nr <= 0) cycle
-            this%gwfsat(nr) = this%bfr%auxvar(1, i)
-          end do
-        case ('STO-SS')
-          do nu = 1, this%dis%nodesuser
-            nr = this%dis%get_nodenumber(nu, 0)
-            if (nr <= 0) cycle
-            this%gwfstrgss(nr) = this%bfr%flow(nu)
-          end do
-        case ('STO-SY')
-          do nu = 1, this%dis%nodesuser
-            nr = this%dis%get_nodenumber(nu, 0)
-            if (nr <= 0) cycle
-            this%gwfstrgsy(nr) = this%bfr%flow(nu)
-          end do
-        case default
-          call this%gwfpackages(ip)%copy_values( &
-            this%bfr%nlist, &
-            this%bfr%nodesrc, &
-            this%bfr%flow, &
-            this%bfr%auxvar)
-          do i = 1, this%gwfpackages(ip)%nbound
-            nu = this%gwfpackages(ip)%nodelist(i)
-            nr = this%dis%get_nodenumber(nu, 0)
-            this%gwfpackages(ip)%nodelist(i) = nr
-          end do
-          ip = ip + 1
-        end select
-      end do
-    else
-      !
-      ! -- write message to indicate that flows are being reused
-      write (this%iout, fmtbudkstpkper) kstp, kper, this%bfr%kstp, this%bfr%kper
-      !
-      ! -- set the flag to indicate that flows were not updated
-      this%iflowsupdated = 0
-    end if
-  end subroutine advance_bfr
-
-  subroutine finalize_bfr(this)
-! ******************************************************************************
-! finalize_bfr -- finalize the budget file reader
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    class(GwtFmiType) :: this
-    ! -- dummy
-! ------------------------------------------------------------------------------
-    !
-    ! -- Finalize the budget file reader
-    call this%bfr%finalize()
-    !
-  end subroutine finalize_bfr
-
-  subroutine initialize_hfr(this)
-! ******************************************************************************
-! initialize_hfr -- initalize the head file reader
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    class(GwtFmiType) :: this
-    ! -- dummy
-! ------------------------------------------------------------------------------
-    !
-    ! -- Initialize the budget file reader
-    call this%hfr%initialize(this%iuhds, this%iout)
-    !
-    ! -- todo: need to run through the head terms
-    !    and do some checking
-  end subroutine initialize_hfr
-
-  subroutine advance_hfr(this)
-! ******************************************************************************
-! advance_hfr -- advance the head file reader
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use TdisModule, only: kstp, kper
-    class(GwtFmiType) :: this
-    integer(I4B) :: nu, nr, i, ilay
-    integer(I4B) :: ncpl
-    real(DP) :: val
-    logical :: readnext
-    logical :: success
-    character(len=*), parameter :: fmtkstpkper = &
-      &"(1x,/1x,'FMI READING HEAD FOR KSTP ', i0, ' KPER ', i0)"
-    character(len=*), parameter :: fmthdskstpkper = &
-      "(1x,/1x, 'FMI SETTING HEAD FOR KSTP ', i0, ' AND KPER ', &
-      &i0, ' TO BINARY FILE HEADS FROM KSTP ', i0, ' AND KPER ', i0)"
-! ------------------------------------------------------------------------------
-    !
-    ! -- If the latest record read from the head file is from a stress
-    ! -- period with only one time step, reuse that record (do not read a
-    ! -- new record) if the GWT model is still in that same stress period,
-    ! -- or if that record is the last one in the head file.
-    readnext = .true.
-    if (kstp * kper > 1) then
-      if (this%hfr%kstp == 1) then
-        if (this%hfr%kpernext == kper + 1) then
-          readnext = .false.
-        else if (this%hfr%endoffile) then
-          readnext = .false.
-        end if
-      else if (this%hfr%endoffile) then
-        write (errmsg, '(a)') 'Reached end of GWF head &
-          &file before reading sufficient head information for this &
-          &GWT simulation.'
-        call store_error(errmsg)
-        call store_error_unit(this%iuhds)
-      end if
-    end if
-    !
-    ! -- Read the next record
-    if (readnext) then
-      !
-      ! -- write to list file that heads are being read
-      write (this%iout, fmtkstpkper) kstp, kper
-      !
-      ! -- loop through the layered heads for this time step
-      do ilay = 1, this%hfr%nlay
-        !
-        ! -- read next head chunk
-        call this%hfr%read_record(success, this%iout)
-        if (.not. success) then
-          write (errmsg, '(a)') 'GWF head read not successful'
-          call store_error(errmsg)
-          call store_error_unit(this%iuhds)
-        end if
-        !
-        ! -- Ensure kper is same between model and head file
-        if (kper /= this%hfr%kper) then
-          write (errmsg, '(a)') 'Period number in head file &
-            &does not match period number in transport model.  If there &
-            &is more than one time step in the head file for a given stress &
-            &period, head file time steps must match gwt model time steps &
-            &one-for-one in that stress period.'
-          call store_error(errmsg)
-          call store_error_unit(this%iuhds)
-        end if
-        !
-        ! -- if head file kstp > 1, then kstp must match
-        if (this%hfr%kstp > 1 .and. (kstp /= this%hfr%kstp)) then
-          write (errmsg, '(a)') 'Time step number in head file &
-            &does not match time step number in transport model.  If there &
-            &is more than one time step in the head file for a given stress &
-            &period, head file time steps must match gwt model time steps &
-            &one-for-one in that stress period.'
-          call store_error(errmsg)
-          call store_error_unit(this%iuhds)
-        end if
-        !
-        ! -- fill the head array for this layer and
-        !    compress into reduced form
-        ncpl = size(this%hfr%head)
-        do i = 1, ncpl
-          nu = (ilay - 1) * ncpl + i
-          nr = this%dis%get_nodenumber(nu, 0)
-          val = this%hfr%head(i)
-          if (nr > 0) this%gwfhead(nr) = val
-        end do
-      end do
-    else
-      write (this%iout, fmthdskstpkper) kstp, kper, this%hfr%kstp, this%hfr%kper
-    end if
-  end subroutine advance_hfr
-
-  subroutine finalize_hfr(this)
-! ******************************************************************************
-! finalize_hfr -- finalize the head file reader
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    class(GwtFmiType) :: this
-    ! -- dummy
-! ------------------------------------------------------------------------------
-    !
-    ! -- Finalize the head file reader
-    close (this%iuhds)
-    !
-  end subroutine finalize_hfr
-
-  subroutine initialize_gwfterms_from_bfr(this)
-! ******************************************************************************
-! initialize_gwfterms_from_bfr -- initalize terms and figure out how many
-!   different terms and packages are contained within the file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_allocate
-    use SimModule, only: store_error, store_error_unit, count_errors
-    ! -- dummy
-    class(GwtFmiType) :: this
-    ! -- local
-    integer(I4B) :: nflowpack
-    integer(I4B) :: i, ip
-    integer(I4B) :: naux
-    logical :: found_flowja
-    logical :: found_dataspdis
-    logical :: found_datasat
-    logical :: found_stoss
-    logical :: found_stosy
-    integer(I4B), dimension(:), allocatable :: imap
-! ------------------------------------------------------------------------------
-    !
-    ! -- Calculate the number of gwf flow packages
-    allocate (imap(this%bfr%nbudterms))
-    imap(:) = 0
-    nflowpack = 0
-    found_flowja = .false.
-    found_dataspdis = .false.
-    found_datasat = .false.
-    found_stoss = .false.
-    found_stosy = .false.
-    do i = 1, this%bfr%nbudterms
-      select case (trim(adjustl(this%bfr%budtxtarray(i))))
-      case ('FLOW-JA-FACE')
-        found_flowja = .true.
-      case ('DATA-SPDIS')
-        found_dataspdis = .true.
-      case ('DATA-SAT')
-        found_datasat = .true.
-      case ('STO-SS')
-        found_stoss = .true.
-        this%igwfstrgss = 1
-      case ('STO-SY')
-        found_stosy = .true.
-        this%igwfstrgsy = 1
-      case default
-        nflowpack = nflowpack + 1
-        imap(i) = 1
-      end select
-    end do
-    !
-    ! -- allocate gwfpackage arrays (gwfpackages, iatp, datp, ...)
-    call this%allocate_gwfpackages(nflowpack)
-    !
-    ! -- Copy the package name and aux names from budget file reader
-    !    to the gwfpackages derived-type variable
-    ip = 1
-    do i = 1, this%bfr%nbudterms
-      if (imap(i) == 0) cycle
-      call this%gwfpackages(ip)%set_name(this%bfr%dstpackagenamearray(i), &
-                                         this%bfr%budtxtarray(i))
-      naux = this%bfr%nauxarray(i)
-      call this%gwfpackages(ip)%set_auxname(naux, this%bfr%auxtxtarray(1:naux, i))
-      ip = ip + 1
-    end do
-    !
-    ! -- Copy just the package names for the boundary packages into
-    !    the flowpacknamearray
-    ip = 1
-    do i = 1, size(imap)
-      if (imap(i) == 1) then
-        this%flowpacknamearray(ip) = this%bfr%dstpackagenamearray(i)
-        ip = ip + 1
-      end if
-    end do
-    !
-    ! -- Error if specific discharge, saturation or flowja not found
-    if (.not. found_dataspdis) then
-      write (errmsg, '(a)') 'Specific discharge not found in &
-                            &budget file. SAVE_SPECIFIC_DISCHARGE and &
-                            &SAVE_FLOWS must be activated in the NPF package.'
-      call store_error(errmsg)
-    end if
-    if (.not. found_datasat) then
-      write (errmsg, '(a)') 'Saturation not found in &
-                            &budget file. SAVE_SATURATION and &
-                            &SAVE_FLOWS must be activated in the NPF package.'
-      call store_error(errmsg)
-    end if
-    if (.not. found_flowja) then
-      write (errmsg, '(a)') 'FLOWJA not found in &
-                            &budget file. SAVE_FLOWS must &
-                            &be activated in the NPF package.'
-      call store_error(errmsg)
-    end if
-    if (count_errors() > 0) then
-      call this%parser%StoreErrorUnit()
-    end if
-    !
-    ! -- return
-    return
-  end subroutine initialize_gwfterms_from_bfr
-
-  subroutine initialize_gwfterms_from_gwfbndlist(this)
-! ******************************************************************************
-! initialize_gwfterms_from_gwfbndlist -- flows are coming from a gwf-gwt
-!   exchange
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use BndModule, only: BndType, GetBndFromList
-    ! -- dummy
-    class(GwtFmiType) :: this
-    ! -- local
-    integer(I4B) :: ngwfpack
-    integer(I4B) :: ngwfterms
-    integer(I4B) :: ip
-    integer(I4B) :: imover
-    integer(I4B) :: ntomvr
-    integer(I4B) :: iterm
-    character(len=LENPACKAGENAME) :: budtxt
-    class(BndType), pointer :: packobj => null()
-! ------------------------------------------------------------------------------
-    !
-    ! -- determine size of gwf terms
-    ngwfpack = this%gwfbndlist%Count()
-    !
-    ! -- Count number of to-mvr terms, but do not include advanced packages
-    !    as those mover terms are not losses from the cell, but rather flows
-    !    within the advanced package
-    ntomvr = 0
-    do ip = 1, ngwfpack
-      packobj => GetBndFromList(this%gwfbndlist, ip)
-      imover = packobj%imover
-      if (packobj%isadvpak /= 0) imover = 0
-      if (imover /= 0) then
-        ntomvr = ntomvr + 1
-      end if
-    end do
-    !
-    ! -- Allocate arrays in fmi of size ngwfterms, which is the number of
-    !    packages plus the number of packages with mover terms.
-    ngwfterms = ngwfpack + ntomvr
-    call this%allocate_gwfpackages(ngwfterms)
-    !
-    ! -- Assign values in the fmi package
-    iterm = 1
-    do ip = 1, ngwfpack
-      !
-      ! -- set and store names
-      packobj => GetBndFromList(this%gwfbndlist, ip)
-      budtxt = adjustl(packobj%text)
-      call this%gwfpackages(iterm)%set_name(packobj%packName, budtxt)
-      this%flowpacknamearray(iterm) = packobj%packName
-      call this%gwfpackages(iterm)%set_auxname(packobj%naux, &
-                                               packobj%auxname)
-      iterm = iterm + 1
-      !
-      ! -- if this package has a mover associated with it, then add another
-      !    term that corresponds to the mover flows
-      imover = packobj%imover
-      if (packobj%isadvpak /= 0) imover = 0
-      if (imover /= 0) then
-        budtxt = trim(adjustl(packobj%text))//'-TO-MVR'
-        call this%gwfpackages(iterm)%set_name(packobj%packName, budtxt)
-        this%flowpacknamearray(iterm) = packobj%packName
-        call this%gwfpackages(iterm)%set_auxname(packobj%naux, &
-                                                 packobj%auxname)
-        this%igwfmvrterm(iterm) = 1
-        iterm = iterm + 1
-      end if
-    end do
-    return
-  end subroutine initialize_gwfterms_from_gwfbndlist
-
-  subroutine allocate_gwfpackages(this, ngwfterms)
-! ******************************************************************************
-! allocate_gwfpackages -- gwfpackages is an array of PackageBudget objects.
-!   This routine allocates gwfpackages to the proper size and initializes some
-!   member variables.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use ConstantsModule, only: LENMEMPATH
-    use MemoryManagerModule, only: mem_allocate
-    ! -- dummy
-    class(GwtFmiType) :: this
-    integer(I4B), intent(in) :: ngwfterms
-    ! -- local
-    integer(I4B) :: n
-    character(len=LENMEMPATH) :: memPath
-! ------------------------------------------------------------------------------
-    !
-    ! -- direct allocate
-    allocate (this%gwfpackages(ngwfterms))
-    allocate (this%flowpacknamearray(ngwfterms))
-    allocate (this%datp(ngwfterms))
-    !
-    ! -- mem_allocate
-    call mem_allocate(this%iatp, ngwfterms, 'IATP', this%memoryPath)
-    call mem_allocate(this%igwfmvrterm, ngwfterms, 'IGWFMVRTERM', this%memoryPath)
-    !
-    ! -- initialize
-    this%nflowpack = ngwfterms
-    do n = 1, this%nflowpack
-      this%iatp(n) = 0
-      this%igwfmvrterm(n) = 0
-      this%flowpacknamearray(n) = ''
-      !
-      ! -- Create a mempath for each individual flow package data set
-      !    of the form, MODELNAME/FMI-FTn
-      write (memPath, '(a, i0)') trim(this%memoryPath)//'-FT', n
-      call this%gwfpackages(n)%initialize(memPath)
-    end do
-    !
-    ! -- return
-    return
-  end subroutine allocate_gwfpackages
-
-  subroutine deallocate_gwfpackages(this)
-! ******************************************************************************
-! deallocate_gwfpackages -- memory in the gwfpackages array
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    ! -- dummy
-    class(GwtFmiType) :: this
-    ! -- local
-    integer(I4B) :: n
-! ------------------------------------------------------------------------------
-    !
-    ! -- initialize
-    do n = 1, this%nflowpack
-      call this%gwfpackages(n)%da()
-    end do
-    !
-    ! -- return
-    return
-  end subroutine deallocate_gwfpackages
-
-  subroutine get_package_index(this, name, idx)
-! ******************************************************************************
-! get_package_index -- find the package index for package called name
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use BndModule, only: BndType, GetBndFromList
-    class(GwtFmiType) :: this
-    character(len=*), intent(in) :: name
-    integer(I4B), intent(inout) :: idx
-    ! -- local
-    integer(I4B) :: ip
-! ------------------------------------------------------------------------------
-    !
-    ! -- Look through all the packages and return the index with name
-    idx = 0
-    do ip = 1, size(this%flowpacknamearray)
-      if (this%flowpacknamearray(ip) == name) then
-        idx = ip
-        exit
-      end if
-    end do
-    if (idx == 0) then
-      call store_error('Error in get_package_index.  Could not find '//name, &
-                       terminate=.TRUE.)
-    end if
-    !
-    ! -- return
-    return
-  end subroutine get_package_index
-
-end module GwtFmiModule
diff --git a/src/Model/GroundWaterTransport/gwt1ic1.f90 b/src/Model/GroundWaterTransport/gwt1ic1.f90
deleted file mode 100644
index e9d872a7137..00000000000
--- a/src/Model/GroundWaterTransport/gwt1ic1.f90
+++ /dev/null
@@ -1,114 +0,0 @@
-module GwtIcModule
-
-  use KindModule, only: DP, I4B
-  use GwfIcModule, only: GwfIcType
-  use BlockParserModule, only: BlockParserType
-  use BaseDisModule, only: DisBaseType
-
-  implicit none
-  private
-  public :: GwtIcType
-  public :: ic_cr
-
-  ! -- Most of the GwtIcType functionality comes from GwfIcType
-  type, extends(GwfIcType) :: GwtIcType
-  contains
-    procedure :: read_data
-  end type GwtIcType
-
-contains
-
-  subroutine ic_cr(ic, name_model, inunit, iout, dis)
-! ******************************************************************************
-! ic_cr -- Create a new initial conditions object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- dummy
-    type(GwtIcType), pointer :: ic
-    character(len=*), intent(in) :: name_model
-    integer(I4B), intent(in) :: inunit
-    integer(I4B), intent(in) :: iout
-    class(DisBaseType), pointer, intent(in) :: dis
-! ------------------------------------------------------------------------------
-    !
-    ! -- Create the object
-    allocate (ic)
-    !
-    ! -- create name and memory path
-    call ic%set_names(1, name_model, 'IC', 'IC')
-    !
-    ! -- Allocate scalars
-    call ic%allocate_scalars()
-    !
-    ic%inunit = inunit
-    ic%iout = iout
-    !
-    ! -- set pointers
-    ic%dis => dis
-    !
-    ! -- Initialize block parser
-    call ic%parser%Initialize(ic%inunit, ic%iout)
-    !
-    ! -- Return
-    return
-  end subroutine ic_cr
-
-  subroutine read_data(this)
-! ******************************************************************************
-! read_data
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use ConstantsModule, only: LINELENGTH
-    use SimModule, only: store_error
-    ! -- dummy
-    class(GwtIcType) :: this
-    ! -- local
-    character(len=LINELENGTH) :: errmsg, keyword
-    character(len=:), allocatable :: line
-    integer(I4B) :: istart, istop, lloc, ierr
-    logical :: isfound, endOfBlock
-    character(len=24) :: aname(1)
-    ! -- formats
-! ------------------------------------------------------------------------------
-    !
-    ! -- Setup the label
-    aname(1) = 'INITIAL CONCENTRATION'
-    !
-    ! -- get griddata block
-    call this%parser%GetBlock('GRIDDATA', isfound, ierr)
-    if (isfound) then
-      write (this%iout, '(1x,a)') 'PROCESSING GRIDDATA'
-      do
-        call this%parser%GetNextLine(endOfBlock)
-        if (endOfBlock) exit
-        call this%parser%GetStringCaps(keyword)
-        call this%parser%GetRemainingLine(line)
-        lloc = 1
-        select case (keyword)
-        case ('STRT')
-          call this%dis%read_grid_array(line, lloc, istart, istop, this%iout, &
-                                        this%parser%iuactive, this%strt, &
-                                        aname(1))
-        case default
-          write (errmsg, '(a,a)') 'Unknown GRIDDATA tag: ', &
-            trim(keyword)
-          call store_error(errmsg)
-          call this%parser%StoreErrorUnit()
-        end select
-      end do
-      write (this%iout, '(1x,a)') 'END PROCESSING GRIDDATA'
-    else
-      call store_error('Required GRIDDATA block not found.')
-      call this%parser%StoreErrorUnit()
-    end if
-    !
-    ! -- Return
-    return
-  end subroutine read_data
-
-end module GwtIcModule
diff --git a/src/Model/GroundWaterTransport/gwt1ic1idm.f90 b/src/Model/GroundWaterTransport/gwt1ic1idm.f90
new file mode 100644
index 00000000000..a2fa79f8d63
--- /dev/null
+++ b/src/Model/GroundWaterTransport/gwt1ic1idm.f90
@@ -0,0 +1,79 @@
+! ** Do Not Modify! MODFLOW 6 system generated file. **
+module GwtIcInputModule
+  use ConstantsModule, only: LENVARNAME
+  use InputDefinitionModule, only: InputParamDefinitionType, &
+                                   InputBlockDefinitionType
+  private
+  public gwt_ic_param_definitions
+  public gwt_ic_aggregate_definitions
+  public gwt_ic_block_definitions
+  public GwtIcParamFoundType
+  public gwt_ic_multi_package
+
+  type GwtIcParamFoundType
+    logical :: strt = .false.
+  end type GwtIcParamFoundType
+
+  logical :: gwt_ic_multi_package = .false.
+
+  type(InputParamDefinitionType), parameter :: &
+    gwtic_strt = InputParamDefinitionType &
+    ( &
+    'GWT', & ! component
+    'IC', & ! subcomponent
+    'GRIDDATA', & ! block
+    'STRT', & ! tag name
+    'STRT', & ! fortran variable
+    'DOUBLE1D', & ! type
+    'NODES', & ! shape
+    .true., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .true., & ! layered
+    .false. & ! timeseries
+    )
+
+  type(InputParamDefinitionType), parameter :: &
+    gwt_ic_param_definitions(*) = &
+    [ &
+    gwtic_strt &
+    ]
+
+  type(InputParamDefinitionType), parameter :: &
+    gwt_ic_aggregate_definitions(*) = &
+    [ &
+    InputParamDefinitionType &
+    ( &
+    '', & ! component
+    '', & ! subcomponent
+    '', & ! block
+    '', & ! tag name
+    '', & ! fortran variable
+    '', & ! type
+    '', & ! shape
+    .false., & ! required
+    .false., & ! multi-record
+    .false., & ! preserve case
+    .false., & ! layered
+    .false. & ! timeseries
+    ) &
+    ]
+
+  type(InputBlockDefinitionType), parameter :: &
+    gwt_ic_block_definitions(*) = &
+    [ &
+    InputBlockDefinitionType( &
+    'OPTIONS', & ! blockname
+    .false., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ), &
+    InputBlockDefinitionType( &
+    'GRIDDATA', & ! blockname
+    .true., & ! required
+    .false., & ! aggregate
+    .false. & ! block_variable
+    ) &
+    ]
+
+end module GwtIcInputModule
diff --git a/src/Model/GroundWaterTransport/gwt1idm.f90 b/src/Model/GroundWaterTransport/gwt1idm.f90
index e63fd582106..d2289c5c688 100644
--- a/src/Model/GroundWaterTransport/gwt1idm.f90
+++ b/src/Model/GroundWaterTransport/gwt1idm.f90
@@ -1,5 +1,6 @@
 ! ** Do Not Modify! MODFLOW 6 system generated file. **
 module GwtNamInputModule
+  use ConstantsModule, only: LENVARNAME
   use InputDefinitionModule, only: InputParamDefinitionType, &
                                    InputBlockDefinitionType
   private
@@ -34,7 +35,8 @@ module GwtNamInputModule
     .false., & ! required
     .false., & ! multi-record
     .true., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -50,7 +52,8 @@ module GwtNamInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -66,7 +69,8 @@ module GwtNamInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -82,7 +86,8 @@ module GwtNamInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -98,7 +103,8 @@ module GwtNamInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -114,7 +120,8 @@ module GwtNamInputModule
     .true., & ! required
     .true., & ! multi-record
     .true., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -130,7 +137,8 @@ module GwtNamInputModule
     .false., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -158,7 +166,8 @@ module GwtNamInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
diff --git a/src/Model/GroundWaterTransport/gwt1ist1.f90 b/src/Model/GroundWaterTransport/gwt1ist1.f90
index 99ed8128e4d..ad0a91ee4a0 100644
--- a/src/Model/GroundWaterTransport/gwt1ist1.f90
+++ b/src/Model/GroundWaterTransport/gwt1ist1.f90
@@ -19,7 +19,7 @@ module GwtIstModule
                              LENBUDTXT, DHNOFLO
   use BndModule, only: BndType
   use BudgetModule, only: BudgetType
-  use GwtFmiModule, only: GwtFmiType
+  use TspFmiModule, only: TspFmiType
   use GwtMstModule, only: GwtMstType, get_zero_order_decay
   use OutputControlDataModule, only: OutputControlDataType
   use MatrixBaseModule
@@ -49,7 +49,7 @@ module GwtIstModule
   !<
   type, extends(BndType) :: GwtIstType
 
-    type(GwtFmiType), pointer :: fmi => null() !< pointer to fmi object
+    type(TspFmiType), pointer :: fmi => null() !< pointer to fmi object
     type(GwtMstType), pointer :: mst => null() !< pointer to mst object
 
     integer(I4B), pointer :: icimout => null() !< unit number for binary cim output
@@ -116,7 +116,7 @@ subroutine ist_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
     character(len=*), intent(in) :: pakname !< name of the package
     ! -- local
     type(GwtIstType), pointer :: istobj
-    type(GwtFmiType), pointer :: fmi
+    type(TspFmiType), pointer :: fmi
     type(GwtMstType), pointer :: mst
     !
     ! -- allocate the object and assign values to object variables
diff --git a/src/Model/GroundWaterTransport/gwt1lkt1.f90 b/src/Model/GroundWaterTransport/gwt1lkt1.f90
index 98ef40abcd0..e8775deec83 100644
--- a/src/Model/GroundWaterTransport/gwt1lkt1.f90
+++ b/src/Model/GroundWaterTransport/gwt1lkt1.f90
@@ -37,10 +37,10 @@ module GwtLktModule
   use ConstantsModule, only: DZERO, DONE, LINELENGTH
   use SimModule, only: store_error
   use BndModule, only: BndType, GetBndFromList
-  use GwtFmiModule, only: GwtFmiType
+  use TspFmiModule, only: TspFmiType
   use LakModule, only: LakType
   use ObserveModule, only: ObserveType
-  use GwtAptModule, only: GwtAptType, apt_process_obsID, &
+  use TspAptModule, only: TspAptType, apt_process_obsID, &
                           apt_process_obsID12
   use MatrixBaseModule
 
@@ -52,7 +52,7 @@ module GwtLktModule
   character(len=*), parameter :: flowtype = 'LAK'
   character(len=16) :: text = '             LKT'
 
-  type, extends(GwtAptType) :: GwtLktType
+  type, extends(TspAptType) :: GwtLktType
 
     integer(I4B), pointer :: idxbudrain => null() ! index of rainfall terms in flowbudptr
     integer(I4B), pointer :: idxbudevap => null() ! index of evaporation terms in flowbudptr
@@ -92,14 +92,10 @@ module GwtLktModule
 
 contains
 
+  !> @brief Create a new lkt package
+  !<
   subroutine lkt_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
-                        fmi)
-! ******************************************************************************
-! mwt_create -- Create a New MWT Package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+                        fmi, eqnsclfac, dvt, dvu, dvua)
     ! -- dummy
     class(BndType), pointer :: packobj
     integer(I4B), intent(in) :: id
@@ -108,10 +104,13 @@ subroutine lkt_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
     integer(I4B), intent(in) :: iout
     character(len=*), intent(in) :: namemodel
     character(len=*), intent(in) :: pakname
-    type(GwtFmiType), pointer :: fmi
+    type(TspFmiType), pointer :: fmi
+    real(DP), intent(in), pointer :: eqnsclfac !< governing equation scale factor
+    character(len=*), intent(in) :: dvt !< For GWT, set to "CONCENTRATION" in TspAptType
+    character(len=*), intent(in) :: dvu !< For GWT, set to "mass" in TspAptType
+    character(len=*), intent(in) :: dvua !< For GWT, set to "M" in TspAptType
     ! -- local
     type(GwtLktType), pointer :: lktobj
-! ------------------------------------------------------------------------------
     !
     ! -- allocate the object and assign values to object variables
     allocate (lktobj)
@@ -139,17 +138,21 @@ subroutine lkt_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
     !    the flow packages
     lktobj%fmi => fmi
     !
-    ! -- return
+    ! -- Store pointer to governing equation scale factor
+    lktobj%eqnsclfac => eqnsclfac
+    !
+    ! -- Set labels that will be used in generalized APT class
+    lktobj%depvartype = dvt
+    lktobj%depvarunit = dvu
+    lktobj%depvarunitabbrev = dvua
+    !
+    ! -- Return
     return
   end subroutine lkt_create
 
+  !> @brief Find corresponding lkt package
+  !<
   subroutine find_lkt_package(this)
-! ******************************************************************************
-! find corresponding lkt package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
@@ -160,7 +163,6 @@ subroutine find_lkt_package(this)
     integer(I4B) :: ip, icount
     integer(I4B) :: nbudterm
     logical :: found
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize found to false, and error later if flow package cannot
     !    be found
@@ -270,14 +272,12 @@ subroutine find_lkt_package(this)
     return
   end subroutine find_lkt_package
 
+  !> @brief Add matrix terms related to LKT
+  !!
+  !! This will be called from TspAptType%apt_fc_expanded()
+  !! in order to add matrix terms specifically for LKT
+  !<
   subroutine lkt_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
-! ******************************************************************************
-! lkt_fc_expanded -- this will be called from GwtAptType%apt_fc_expanded()
-!   in order to add matrix terms specifically for LKT
-! ****************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtLktType) :: this
@@ -292,7 +292,6 @@ subroutine lkt_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
     real(DP) :: rrate
     real(DP) :: rhsval
     real(DP) :: hcofval
-! ------------------------------------------------------------------------------
     !
     ! -- add rainfall contribution
     if (this%idxbudrain /= 0) then
@@ -364,20 +363,15 @@ subroutine lkt_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
     return
   end subroutine lkt_fc_expanded
 
+  !> @brief Add terms specific to lakes to the explicit lake solve
+  !<
   subroutine lkt_solve(this)
-! ******************************************************************************
-! lkt_solve -- add terms specific to lakes to the explicit lake solve
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtLktType) :: this
     ! -- local
     integer(I4B) :: j
     integer(I4B) :: n1, n2
     real(DP) :: rrate
-! ------------------------------------------------------------------------------
     !
     ! -- add rainfall contribution
     if (this%idxbudrain /= 0) then
@@ -431,21 +425,17 @@ subroutine lkt_solve(this)
     return
   end subroutine lkt_solve
 
+  !> @brief Function to return the number of budget terms just for this package.
+  !!
+  !! This overrides a function in the parent class.
+  !<
   function lkt_get_nbudterms(this) result(nbudterms)
-! ******************************************************************************
-! lkt_get_nbudterms -- function to return the number of budget terms just for
-!   this package.  This overrides function in parent.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtLktType) :: this
     ! -- return
     integer(I4B) :: nbudterms
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- Number of budget terms is 6
     nbudterms = 6
@@ -454,13 +444,9 @@ function lkt_get_nbudterms(this) result(nbudterms)
     return
   end function lkt_get_nbudterms
 
+  !> @brief Set up the budget object that stores all the lake flows
+  !<
   subroutine lkt_setup_budobj(this, idx)
-! ******************************************************************************
-! lkt_setup_budobj -- Set up the budget object that stores all the lake flows
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LENBUDTXT
     ! -- dummy
@@ -469,9 +455,8 @@ subroutine lkt_setup_budobj(this, idx)
     ! -- local
     integer(I4B) :: maxlist, naux
     character(len=LENBUDTXT) :: text
-! ------------------------------------------------------------------------------
     !
-    ! --
+    ! -- Addition of mass associated with rainfall directly on lake surface
     text = '        RAINFALL'
     idx = idx + 1
     maxlist = this%flowbudptr%budterm(this%idxbudrain)%maxlist
@@ -484,7 +469,8 @@ subroutine lkt_setup_budobj(this, idx)
                                              maxlist, .false., .false., &
                                              naux)
     !
-    ! --
+    ! -- Loss of dissolved mass associated with evaporation when a non-zero
+    !    evaporative concentration is specified
     text = '     EVAPORATION'
     idx = idx + 1
     maxlist = this%flowbudptr%budterm(this%idxbudevap)%maxlist
@@ -497,7 +483,7 @@ subroutine lkt_setup_budobj(this, idx)
                                              maxlist, .false., .false., &
                                              naux)
     !
-    ! --
+    ! -- Addition of mass associated with runoff that flows to the lake
     text = '          RUNOFF'
     idx = idx + 1
     maxlist = this%flowbudptr%budterm(this%idxbudroff)%maxlist
@@ -510,7 +496,7 @@ subroutine lkt_setup_budobj(this, idx)
                                              maxlist, .false., .false., &
                                              naux)
     !
-    ! --
+    ! -- Addition of mass associated with user-specified inflow to the lake
     text = '      EXT-INFLOW'
     idx = idx + 1
     maxlist = this%flowbudptr%budterm(this%idxbudiflw)%maxlist
@@ -523,7 +509,7 @@ subroutine lkt_setup_budobj(this, idx)
                                              maxlist, .false., .false., &
                                              naux)
     !
-    ! --
+    ! -- Removal of mass associated with user-specified withdrawal from lake
     text = '      WITHDRAWAL'
     idx = idx + 1
     maxlist = this%flowbudptr%budterm(this%idxbudwdrl)%maxlist
@@ -536,7 +522,8 @@ subroutine lkt_setup_budobj(this, idx)
                                              maxlist, .false., .false., &
                                              naux)
     !
-    ! --
+    ! -- Removal of heat associated with outflow from lake that leaves
+    !    model domain
     text = '     EXT-OUTFLOW'
     idx = idx + 1
     maxlist = this%flowbudptr%budterm(this%idxbudoutf)%maxlist
@@ -549,17 +536,13 @@ subroutine lkt_setup_budobj(this, idx)
                                              maxlist, .false., .false., &
                                              naux)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lkt_setup_budobj
 
+  !> @brief Copy flow terms into this%budobj
+  !<
   subroutine lkt_fill_budobj(this, idx, x, ccratin, ccratout)
-! ******************************************************************************
-! lkt_fill_budobj -- copy flow terms into this%budobj
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtLktType) :: this
@@ -572,8 +555,7 @@ subroutine lkt_fill_budobj(this, idx, x, ccratin, ccratout)
     integer(I4B) :: nlist
     real(DP) :: q
     ! -- formats
-! -----------------------------------------------------------------------------
-
+    !
     ! -- RAIN
     idx = idx + 1
     nlist = this%flowbudptr%budterm(this%idxbudrain)%nlist
@@ -583,7 +565,7 @@ subroutine lkt_fill_budobj(this, idx, x, ccratin, ccratout)
       call this%budobj%budterm(idx)%update_term(n1, n2, q)
       call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
     end do
-
+    !
     ! -- EVAPORATION
     idx = idx + 1
     nlist = this%flowbudptr%budterm(this%idxbudevap)%nlist
@@ -593,7 +575,7 @@ subroutine lkt_fill_budobj(this, idx, x, ccratin, ccratout)
       call this%budobj%budterm(idx)%update_term(n1, n2, q)
       call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
     end do
-
+    !
     ! -- RUNOFF
     idx = idx + 1
     nlist = this%flowbudptr%budterm(this%idxbudroff)%nlist
@@ -603,7 +585,7 @@ subroutine lkt_fill_budobj(this, idx, x, ccratin, ccratout)
       call this%budobj%budterm(idx)%update_term(n1, n2, q)
       call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
     end do
-
+    !
     ! -- EXT-INFLOW
     idx = idx + 1
     nlist = this%flowbudptr%budterm(this%idxbudiflw)%nlist
@@ -613,7 +595,7 @@ subroutine lkt_fill_budobj(this, idx, x, ccratin, ccratout)
       call this%budobj%budterm(idx)%update_term(n1, n2, q)
       call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
     end do
-
+    !
     ! -- WITHDRAWAL
     idx = idx + 1
     nlist = this%flowbudptr%budterm(this%idxbudwdrl)%nlist
@@ -623,7 +605,7 @@ subroutine lkt_fill_budobj(this, idx, x, ccratin, ccratout)
       call this%budobj%budterm(idx)%update_term(n1, n2, q)
       call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
     end do
-
+    !
     ! -- EXT-OUTFLOW
     idx = idx + 1
     nlist = this%flowbudptr%budterm(this%idxbudoutf)%nlist
@@ -633,28 +615,23 @@ subroutine lkt_fill_budobj(this, idx, x, ccratin, ccratout)
       call this%budobj%budterm(idx)%update_term(n1, n2, q)
       call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
     end do
-
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lkt_fill_budobj
 
+  !> @brief Allocate scalars specific to the lake mass transport (LKT)
+  !! package.
+  !<
   subroutine allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwtLktType) :: this
     ! -- local
-! ------------------------------------------------------------------------------
     !
-    ! -- allocate scalars in GwtAptType
-    call this%GwtAptType%allocate_scalars()
+    ! -- allocate scalars in TspAptType
+    call this%TspAptType%allocate_scalars()
     !
     ! -- Allocate
     call mem_allocate(this%idxbudrain, 'IDXBUDRAIN', this%memoryPath)
@@ -676,20 +653,16 @@ subroutine allocate_scalars(this)
     return
   end subroutine allocate_scalars
 
+  !> @brief Allocate arrays specific to the lake mass transport (LKT)
+  !! package.
+  !<
   subroutine lkt_allocate_arrays(this)
-! ******************************************************************************
-! lkt_allocate_arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwtLktType), intent(inout) :: this
     ! -- local
     integer(I4B) :: n
-! ------------------------------------------------------------------------------
     !
     ! -- time series
     call mem_allocate(this%concrain, this%ncv, 'CONCRAIN', this%memoryPath)
@@ -697,8 +670,8 @@ subroutine lkt_allocate_arrays(this)
     call mem_allocate(this%concroff, this%ncv, 'CONCROFF', this%memoryPath)
     call mem_allocate(this%conciflw, this%ncv, 'CONCIFLW', this%memoryPath)
     !
-    ! -- call standard GwtApttype allocate arrays
-    call this%GwtAptType%apt_allocate_arrays()
+    ! -- call standard TspAptType allocate arrays
+    call this%TspAptType%apt_allocate_arrays()
     !
     ! -- Initialize
     do n = 1, this%ncv
@@ -713,19 +686,14 @@ subroutine lkt_allocate_arrays(this)
     return
   end subroutine lkt_allocate_arrays
 
+  !> @brief Deallocate memory
+  !<
   subroutine lkt_da(this)
-! ******************************************************************************
-! lkt_da
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(GwtLktType) :: this
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- deallocate scalars
     call mem_deallocate(this%idxbudrain)
@@ -741,21 +709,17 @@ subroutine lkt_da(this)
     call mem_deallocate(this%concroff)
     call mem_deallocate(this%conciflw)
     !
-    ! -- deallocate scalars in GwtAptType
-    call this%GwtAptType%bnd_da()
+    ! -- deallocate scalars in TspAptType
+    call this%TspAptType%bnd_da()
     !
     ! -- Return
     return
   end subroutine lkt_da
 
+  !> @brief Rain term
+  !<
   subroutine lkt_rain_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! lkt_rain_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtLktType) :: this
     integer(I4B), intent(in) :: ientry
@@ -767,7 +731,7 @@ subroutine lkt_rain_term(this, ientry, n1, n2, rrate, &
     ! -- local
     real(DP) :: qbnd
     real(DP) :: ctmp
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudrain)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudrain)%id2(ientry)
     qbnd = this%flowbudptr%budterm(this%idxbudrain)%flow(ientry)
@@ -776,18 +740,14 @@ subroutine lkt_rain_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = -rrate
     if (present(hcofval)) hcofval = DZERO
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lkt_rain_term
 
+  !> @brief Evaporative term
+  !<
   subroutine lkt_evap_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! lkt_evap_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtLktType) :: this
     integer(I4B), intent(in) :: ientry
@@ -800,7 +760,7 @@ subroutine lkt_evap_term(this, ientry, n1, n2, rrate, &
     real(DP) :: qbnd
     real(DP) :: ctmp
     real(DP) :: omega
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudevap)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudevap)%id2(ientry)
     ! -- note that qbnd is negative for evap
@@ -817,18 +777,14 @@ subroutine lkt_evap_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = -(DONE - omega) * qbnd * ctmp
     if (present(hcofval)) hcofval = omega * qbnd
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lkt_evap_term
 
+  !> @brief Runoff term
+  !<
   subroutine lkt_roff_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! lkt_roff_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtLktType) :: this
     integer(I4B), intent(in) :: ientry
@@ -840,7 +796,7 @@ subroutine lkt_roff_term(this, ientry, n1, n2, rrate, &
     ! -- local
     real(DP) :: qbnd
     real(DP) :: ctmp
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudroff)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudroff)%id2(ientry)
     qbnd = this%flowbudptr%budterm(this%idxbudroff)%flow(ientry)
@@ -849,18 +805,17 @@ subroutine lkt_roff_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = -rrate
     if (present(hcofval)) hcofval = DZERO
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lkt_roff_term
 
+  !> @brief Inflow Term
+  !!
+  !! Accounts for mass flowing into a lake from a connected stream, for
+  !! example.
+  !<
   subroutine lkt_iflw_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! lkt_iflw_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtLktType) :: this
     integer(I4B), intent(in) :: ientry
@@ -872,7 +827,7 @@ subroutine lkt_iflw_term(this, ientry, n1, n2, rrate, &
     ! -- local
     real(DP) :: qbnd
     real(DP) :: ctmp
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudiflw)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudiflw)%id2(ientry)
     qbnd = this%flowbudptr%budterm(this%idxbudiflw)%flow(ientry)
@@ -881,18 +836,17 @@ subroutine lkt_iflw_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = -rrate
     if (present(hcofval)) hcofval = DZERO
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lkt_iflw_term
 
+  !> @brief Specified withdrawal term
+  !!
+  !! Accounts for mass associated with a withdrawal of water from a lake
+  !! or group of lakes.
+  !<
   subroutine lkt_wdrl_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! lkt_wdrl_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtLktType) :: this
     integer(I4B), intent(in) :: ientry
@@ -904,7 +858,7 @@ subroutine lkt_wdrl_term(this, ientry, n1, n2, rrate, &
     ! -- local
     real(DP) :: qbnd
     real(DP) :: ctmp
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudwdrl)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudwdrl)%id2(ientry)
     qbnd = this%flowbudptr%budterm(this%idxbudwdrl)%flow(ientry)
@@ -913,18 +867,17 @@ subroutine lkt_wdrl_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = DZERO
     if (present(hcofval)) hcofval = qbnd
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lkt_wdrl_term
 
+  !> @brief Outflow term
+  !!
+  !! Accounts for the mass leaving a lake, for example, mass exiting a
+  !! lake via a flow into a draining stream channel.
+  !<
   subroutine lkt_outf_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! lkt_outf_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtLktType) :: this
     integer(I4B), intent(in) :: ientry
@@ -936,7 +889,7 @@ subroutine lkt_outf_term(this, ientry, n1, n2, rrate, &
     ! -- local
     real(DP) :: qbnd
     real(DP) :: ctmp
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudoutf)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudoutf)%id2(ientry)
     qbnd = this%flowbudptr%budterm(this%idxbudoutf)%flow(ientry)
@@ -945,25 +898,21 @@ subroutine lkt_outf_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = DZERO
     if (present(hcofval)) hcofval = qbnd
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lkt_outf_term
 
+  !> @brief Defined observation types
+  !!
+  !! Store the observation type supported by the APT package and overide
+  !! BndType%bnd_df_obs
+  !<
   subroutine lkt_df_obs(this)
-! ******************************************************************************
-! lkt_df_obs -- obs are supported?
-!   -- Store observation type supported by APT package.
-!   -- Overrides BndType%bnd_df_obs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtLktType) :: this
     ! -- local
     integer(I4B) :: indx
-! ------------------------------------------------------------------------------
     !
     ! -- Store obs type and assign procedure pointer
     !    for concentration observation type.
@@ -1030,13 +979,13 @@ subroutine lkt_df_obs(this)
     call this%obs%StoreObsType('ext-outflow', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => apt_process_obsID
     !
+    ! -- Return
     return
   end subroutine lkt_df_obs
 
   !> @brief Process package specific obs
-    !!
-    !! Method to process specific observations for this package.
-    !!
+  !!
+  !! Method to process specific observations for this package.
   !<
   subroutine lkt_rp_obs(this, obsrv, found)
     ! -- dummy
@@ -1066,16 +1015,13 @@ subroutine lkt_rp_obs(this, obsrv, found)
       found = .false.
     end select
     !
+    ! -- Return
     return
   end subroutine lkt_rp_obs
 
+  !> @brief Calculate observation value and pass it back to APT
+  !<
   subroutine lkt_bd_obs(this, obstypeid, jj, v, found)
-! ******************************************************************************
-! lkt_bd_obs -- calculate observation value and pass it back to APT
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtLktType), intent(inout) :: this
     character(len=*), intent(in) :: obstypeid
@@ -1084,7 +1030,6 @@ subroutine lkt_bd_obs(this, obstypeid, jj, v, found)
     logical, intent(inout) :: found
     ! -- local
     integer(I4B) :: n1, n2
-! ------------------------------------------------------------------------------
     !
     found = .true.
     select case (obstypeid)
@@ -1116,16 +1061,13 @@ subroutine lkt_bd_obs(this, obstypeid, jj, v, found)
       found = .false.
     end select
     !
+    ! -- Return
     return
   end subroutine lkt_bd_obs
 
+  !> @brief Sets the stress period attributes for keyword use.
+  !<
   subroutine lkt_set_stressperiod(this, itemno, keyword, found)
-! ******************************************************************************
-! lkt_set_stressperiod -- Set a stress period attribute for using keywords.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use TimeSeriesManagerModule, only: read_value_or_time_series_adv
     ! -- dummy
     class(GwtLktType), intent(inout) :: this
@@ -1138,7 +1080,6 @@ subroutine lkt_set_stressperiod(this, itemno, keyword, found)
     integer(I4B) :: jj
     real(DP), pointer :: bndElem => null()
     ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! RAINFALL <rainfall>
     ! EVAPORATION <evaporation>
@@ -1200,7 +1141,7 @@ subroutine lkt_set_stressperiod(this, itemno, keyword, found)
     !
 999 continue
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine lkt_set_stressperiod
 
diff --git a/src/Model/GroundWaterTransport/gwt1mst1.f90 b/src/Model/GroundWaterTransport/gwt1mst1.f90
index f962a5f2bef..48842e211b5 100644
--- a/src/Model/GroundWaterTransport/gwt1mst1.f90
+++ b/src/Model/GroundWaterTransport/gwt1mst1.f90
@@ -17,7 +17,7 @@ module GwtMstModule
   use MatrixBaseModule
   use NumericalPackageModule, only: NumericalPackageType
   use BaseDisModule, only: DisBaseType
-  use GwtFmiModule, only: GwtFmiType
+  use TspFmiModule, only: TspFmiType
 
   implicit none
   public :: GwtMstType
@@ -60,7 +60,7 @@ module GwtMstModule
     !
     ! -- misc
     integer(I4B), dimension(:), pointer, contiguous :: ibound => null() !< pointer to model ibound
-    type(GwtFmiType), pointer :: fmi => null() !< pointer to fmi object
+    type(TspFmiType), pointer :: fmi => null() !< pointer to fmi object
 
   contains
 
@@ -100,7 +100,7 @@ subroutine mst_cr(mstobj, name_model, inunit, iout, fmi)
     character(len=*), intent(in) :: name_model !< name of the model
     integer(I4B), intent(in) :: inunit !< unit number of WEL package input file
     integer(I4B), intent(in) :: iout !< unit number of model listing file
-    type(GwtFmiType), intent(in), target :: fmi !< fmi package for this GWT model
+    type(TspFmiType), intent(in), target :: fmi !< fmi package for this GWT model
     !
     ! -- Create the object
     allocate (mstobj)
diff --git a/src/Model/GroundWaterTransport/gwt1mwt1.f90 b/src/Model/GroundWaterTransport/gwt1mwt1.f90
index 15137d3a5c6..842a051235f 100644
--- a/src/Model/GroundWaterTransport/gwt1mwt1.f90
+++ b/src/Model/GroundWaterTransport/gwt1mwt1.f90
@@ -38,10 +38,10 @@ module GwtMwtModule
   use ConstantsModule, only: DZERO, LINELENGTH
   use SimModule, only: store_error
   use BndModule, only: BndType, GetBndFromList
-  use GwtFmiModule, only: GwtFmiType
+  use TspFmiModule, only: TspFmiType
   use MawModule, only: MawType
   use ObserveModule, only: ObserveType
-  use GwtAptModule, only: GwtAptType, apt_process_obsID, &
+  use TspAptModule, only: TspAptType, apt_process_obsID, &
                           apt_process_obsID12
   use MatrixBaseModule
 
@@ -53,7 +53,7 @@ module GwtMwtModule
   character(len=*), parameter :: flowtype = 'MAW'
   character(len=16) :: text = '             MWT'
 
-  type, extends(GwtAptType) :: GwtMwtType
+  type, extends(TspAptType) :: GwtMwtType
 
     integer(I4B), pointer :: idxbudrate => null() ! index of well rate terms in flowbudptr
     integer(I4B), pointer :: idxbudfwrt => null() ! index of flowing well rate terms in flowbudptr
@@ -85,14 +85,10 @@ module GwtMwtModule
 
 contains
 
+  !> Create new MWT package
+  !<
   subroutine mwt_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
-                        fmi)
-! ******************************************************************************
-! mwt_create -- Create a New MWT Package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+                        fmi, eqnsclfac, dvt, dvu, dvua)
     ! -- dummy
     class(BndType), pointer :: packobj
     integer(I4B), intent(in) :: id
@@ -101,10 +97,13 @@ subroutine mwt_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
     integer(I4B), intent(in) :: iout
     character(len=*), intent(in) :: namemodel
     character(len=*), intent(in) :: pakname
-    type(GwtFmiType), pointer :: fmi
+    type(TspFmiType), pointer :: fmi
+    real(DP), intent(in), pointer :: eqnsclfac !< governing equation scale factor
+    character(len=*), intent(in) :: dvt !< For GWT, set to "CONCENTRATION" in TspAptType
+    character(len=*), intent(in) :: dvu !< For GWT, set to "mass" in TspAptType
+    character(len=*), intent(in) :: dvua !< For GWT, set to "M" in TspAptType
     ! -- local
     type(GwtMwtType), pointer :: mwtobj
-! ------------------------------------------------------------------------------
     !
     ! -- allocate the object and assign values to object variables
     allocate (mwtobj)
@@ -132,17 +131,21 @@ subroutine mwt_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
     !    the flow packages
     mwtobj%fmi => fmi
     !
-    ! -- return
+    ! -- Store pointer to governing equation scale factor
+    mwtobj%eqnsclfac => eqnsclfac
+    !
+    ! -- Set labels that will be used in generalized APT class
+    mwtobj%depvartype = dvt
+    mwtobj%depvarunit = dvu
+    mwtobj%depvarunitabbrev = dvua
+    !
+    ! -- Return
     return
   end subroutine mwt_create
 
+  !> @brief find corresponding mwt package
+  !<
   subroutine find_mwt_package(this)
-! ******************************************************************************
-! find corresponding mwt package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
@@ -153,7 +156,6 @@ subroutine find_mwt_package(this)
     integer(I4B) :: ip, icount
     integer(I4B) :: nbudterm
     logical :: found
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize found to false, and error later if flow package cannot
     !    be found
@@ -257,14 +259,12 @@ subroutine find_mwt_package(this)
     return
   end subroutine find_mwt_package
 
+  !> @brief Add matrix terms related to MWT
+  !!
+  !! This routine is called from TspAptType%apt_fc_expanded() in
+  !! order to add matrix terms specifically for MWT
+  !<
   subroutine mwt_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
-! ******************************************************************************
-! mwt_fc_expanded -- this will be called from GwtAptType%apt_fc_expanded()
-!   in order to add matrix terms specifically for this package
-! ****************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtMwtType) :: this
@@ -279,7 +279,6 @@ subroutine mwt_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
     real(DP) :: rrate
     real(DP) :: rhsval
     real(DP) :: hcofval
-! ------------------------------------------------------------------------------
     !
     ! -- add puping rate contribution
     if (this%idxbudrate /= 0) then
@@ -329,21 +328,16 @@ subroutine mwt_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
     return
   end subroutine mwt_fc_expanded
 
+  !> @ brief Add terms specific to multi-aquifer wells to the explicit multi-
+  !! aquifer well solute transport solve
+  !<
   subroutine mwt_solve(this)
-! ******************************************************************************
-! mwt_solve -- add terms specific to multi-aquifer wells to the explicit multi-
-!              aquifer well solve
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtMwtType) :: this
     ! -- local
     integer(I4B) :: j
     integer(I4B) :: n1, n2
     real(DP) :: rrate
-! ------------------------------------------------------------------------------
     !
     ! -- add well pumping contribution
     if (this%idxbudrate /= 0) then
@@ -381,21 +375,17 @@ subroutine mwt_solve(this)
     return
   end subroutine mwt_solve
 
+  !> @brief Function to return the number of budget terms just for this package
+  !!
+  !! This overrides a function in the parent class.
+  !<
   function mwt_get_nbudterms(this) result(nbudterms)
-! ******************************************************************************
-! mwt_get_nbudterms -- function to return the number of budget terms just for
-!   this package.  This overrides function in parent.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtMwtType) :: this
-    ! -- return
+    ! -- Return
     integer(I4B) :: nbudterms
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- Number of budget terms is 4
     nbudterms = 1
@@ -407,14 +397,9 @@ function mwt_get_nbudterms(this) result(nbudterms)
     return
   end function mwt_get_nbudterms
 
+  !> @brief Set up the budget object that stores all the mwt flows
+  !<
   subroutine mwt_setup_budobj(this, idx)
-! ******************************************************************************
-! mwt_setup_budobj -- Set up the budget object that stores all the multi-
-!                     aquifer well flows
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LENBUDTXT
     ! -- dummy
@@ -423,7 +408,6 @@ subroutine mwt_setup_budobj(this, idx)
     ! -- local
     integer(I4B) :: maxlist, naux
     character(len=LENBUDTXT) :: text
-! ------------------------------------------------------------------------------
     !
     ! --
     text = '            RATE'
@@ -437,7 +421,6 @@ subroutine mwt_setup_budobj(this, idx)
                                              this%packName, &
                                              maxlist, .false., .false., &
                                              naux)
-
     !
     ! --
     if (this%idxbudfwrt /= 0) then
@@ -453,7 +436,6 @@ subroutine mwt_setup_budobj(this, idx)
                                                maxlist, .false., .false., &
                                                naux)
     end if
-
     !
     ! --
     if (this%idxbudrtmv /= 0) then
@@ -469,7 +451,6 @@ subroutine mwt_setup_budobj(this, idx)
                                                maxlist, .false., .false., &
                                                naux)
     end if
-
     !
     ! --
     if (this%idxbudfrtm /= 0) then
@@ -485,19 +466,14 @@ subroutine mwt_setup_budobj(this, idx)
                                                maxlist, .false., .false., &
                                                naux)
     end if
-
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine mwt_setup_budobj
 
+  !> @brief Copy flow terms into this%budobj
+  !<
   subroutine mwt_fill_budobj(this, idx, x, ccratin, ccratout)
-! ******************************************************************************
-! mwt_fill_budobj -- copy flow terms into this%budobj
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtMwtType) :: this
@@ -510,8 +486,7 @@ subroutine mwt_fill_budobj(this, idx, x, ccratin, ccratout)
     integer(I4B) :: nlist
     real(DP) :: q
     ! -- formats
-! -----------------------------------------------------------------------------
-
+    !
     ! -- RATE
     idx = idx + 1
     nlist = this%flowbudptr%budterm(this%idxbudrate)%nlist
@@ -521,7 +496,7 @@ subroutine mwt_fill_budobj(this, idx, x, ccratin, ccratout)
       call this%budobj%budterm(idx)%update_term(n1, n2, q)
       call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
     end do
-
+    !
     ! -- FW-RATE
     if (this%idxbudfwrt /= 0) then
       idx = idx + 1
@@ -533,7 +508,7 @@ subroutine mwt_fill_budobj(this, idx, x, ccratin, ccratout)
         call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
       end do
     end if
-
+    !
     ! -- RATE-TO-MVR
     if (this%idxbudrtmv /= 0) then
       idx = idx + 1
@@ -545,7 +520,7 @@ subroutine mwt_fill_budobj(this, idx, x, ccratin, ccratout)
         call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
       end do
     end if
-
+    !
     ! -- FW-RATE-TO-MVR
     if (this%idxbudfrtm /= 0) then
       idx = idx + 1
@@ -557,28 +532,23 @@ subroutine mwt_fill_budobj(this, idx, x, ccratin, ccratout)
         call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
       end do
     end if
-
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine mwt_fill_budobj
 
+  !> @brief Allocate scalars specific to the streamflow mass transport (SFT)
+  !! package.
+  !<
   subroutine allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwtMwtType) :: this
     ! -- local
-! ------------------------------------------------------------------------------
     !
-    ! -- allocate scalars in GwtAptType
-    call this%GwtAptType%allocate_scalars()
+    ! -- allocate scalars in TspAptType
+    call this%TspAptType%allocate_scalars()
     !
     ! -- Allocate
     call mem_allocate(this%idxbudrate, 'IDXBUDRATE', this%memoryPath)
@@ -596,26 +566,22 @@ subroutine allocate_scalars(this)
     return
   end subroutine allocate_scalars
 
+  !> @brief Allocate arrays specific to the streamflow mass transport (SFT)
+  !! package.
+  !<
   subroutine mwt_allocate_arrays(this)
-! ******************************************************************************
-! mwt_allocate_arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwtMwtType), intent(inout) :: this
     ! -- local
     integer(I4B) :: n
-! ------------------------------------------------------------------------------
     !
     ! -- time series
     call mem_allocate(this%concrate, this%ncv, 'CONCRATE', this%memoryPath)
     !
-    ! -- call standard GwtApttype allocate arrays
-    call this%GwtAptType%apt_allocate_arrays()
+    ! -- call standard TspAptType allocate arrays
+    call this%TspAptType%apt_allocate_arrays()
     !
     ! -- Initialize
     do n = 1, this%ncv
@@ -627,19 +593,14 @@ subroutine mwt_allocate_arrays(this)
     return
   end subroutine mwt_allocate_arrays
 
+  !> @brief Deallocate memory
+  !<
   subroutine mwt_da(this)
-! ******************************************************************************
-! mwt_da
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(GwtMwtType) :: this
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- deallocate scalars
     call mem_deallocate(this%idxbudrate)
@@ -650,21 +611,17 @@ subroutine mwt_da(this)
     ! -- deallocate time series
     call mem_deallocate(this%concrate)
     !
-    ! -- deallocate scalars in GwtAptType
-    call this%GwtAptType%bnd_da()
+    ! -- deallocate scalars in TspAptType
+    call this%TspAptType%bnd_da()
     !
     ! -- Return
     return
   end subroutine mwt_da
 
+  !> @brief Rate term associated with pumping (or injection)
+  !<
   subroutine mwt_rate_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! mwt_rate_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtMwtType) :: this
     integer(I4B), intent(in) :: ientry
@@ -677,7 +634,7 @@ subroutine mwt_rate_term(this, ientry, n1, n2, rrate, &
     real(DP) :: qbnd
     real(DP) :: ctmp
     real(DP) :: h, r
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudrate)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudrate)%id2(ientry)
     ! -- note that qbnd is negative for extracting well
@@ -695,18 +652,15 @@ subroutine mwt_rate_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = r
     if (present(hcofval)) hcofval = h
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine mwt_rate_term
 
+  !> @brief Transport matrix term(s) associcated with a flowing-
+  !! well rate term associated with pumping (or injection)
+  !<
   subroutine mwt_fwrt_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! mwt_fwrt_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtMwtType) :: this
     integer(I4B), intent(in) :: ientry
@@ -718,7 +672,7 @@ subroutine mwt_fwrt_term(this, ientry, n1, n2, rrate, &
     ! -- local
     real(DP) :: qbnd
     real(DP) :: ctmp
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudfwrt)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudfwrt)%id2(ientry)
     qbnd = this%flowbudptr%budterm(this%idxbudfwrt)%flow(ientry)
@@ -727,18 +681,17 @@ subroutine mwt_fwrt_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = DZERO
     if (present(hcofval)) hcofval = qbnd
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine mwt_fwrt_term
 
+  !> @brief Rate-to-mvr term associated with pumping (or injection)
+  !!
+  !! Pumped water that is made available to the MVR package for transfer to
+  !! another advanced package
+  !<
   subroutine mwt_rtmv_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! mwt_rtmv_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtMwtType) :: this
     integer(I4B), intent(in) :: ientry
@@ -750,7 +703,7 @@ subroutine mwt_rtmv_term(this, ientry, n1, n2, rrate, &
     ! -- local
     real(DP) :: qbnd
     real(DP) :: ctmp
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudrtmv)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudrtmv)%id2(ientry)
     qbnd = this%flowbudptr%budterm(this%idxbudrtmv)%flow(ientry)
@@ -759,18 +712,17 @@ subroutine mwt_rtmv_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = DZERO
     if (present(hcofval)) hcofval = qbnd
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine mwt_rtmv_term
 
+  !> @brief Flowing well rate-to-mvr term (or injection)
+  !!
+  !! Pumped water that is made available to the MVR package for transfer to
+  !! another advanced package
+  !<
   subroutine mwt_frtm_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! mwt_frtm_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtMwtType) :: this
     integer(I4B), intent(in) :: ientry
@@ -782,7 +734,7 @@ subroutine mwt_frtm_term(this, ientry, n1, n2, rrate, &
     ! -- local
     real(DP) :: qbnd
     real(DP) :: ctmp
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudfrtm)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudfrtm)%id2(ientry)
     qbnd = this%flowbudptr%budterm(this%idxbudfrtm)%flow(ientry)
@@ -791,25 +743,21 @@ subroutine mwt_frtm_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = DZERO
     if (present(hcofval)) hcofval = qbnd
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine mwt_frtm_term
 
+  !> @brief Observations
+  !!
+  !! Store the observation type supported by the APT package and overide
+  !! BndType%bnd_df_obs
+  !<
   subroutine mwt_df_obs(this)
-! ******************************************************************************
-! mwt_df_obs -- obs are supported?
-!   -- Store observation type supported by APT package.
-!   -- Overrides BndType%bnd_df_obs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtMwtType) :: this
     ! -- local
     integer(I4B) :: indx
-! ------------------------------------------------------------------------------
     !
     ! -- Store obs type and assign procedure pointer
     !    for concentration observation type.
@@ -864,13 +812,13 @@ subroutine mwt_df_obs(this)
     call this%obs%StoreObsType('fw-rate-to-mvr', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => apt_process_obsID
     !
+    ! -- Return
     return
   end subroutine mwt_df_obs
 
   !> @brief Process package specific obs
-    !!
-    !! Method to process specific observations for this package.
-    !!
+  !!
+  !! Method to process specific observations for this package.
   !<
   subroutine mwt_rp_obs(this, obsrv, found)
     ! -- dummy
@@ -893,16 +841,13 @@ subroutine mwt_rp_obs(this, obsrv, found)
       found = .false.
     end select
     !
+    ! -- Return
     return
   end subroutine mwt_rp_obs
 
+  !> @brief Calculate observation value and pass it back to APT
+  !<
   subroutine mwt_bd_obs(this, obstypeid, jj, v, found)
-! ******************************************************************************
-! mwt_bd_obs -- calculate observation value and pass it back to APT
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtMwtType), intent(inout) :: this
     character(len=*), intent(in) :: obstypeid
@@ -911,7 +856,6 @@ subroutine mwt_bd_obs(this, obstypeid, jj, v, found)
     logical, intent(inout) :: found
     ! -- local
     integer(I4B) :: n1, n2
-! ------------------------------------------------------------------------------
     !
     found = .true.
     select case (obstypeid)
@@ -935,16 +879,14 @@ subroutine mwt_bd_obs(this, obstypeid, jj, v, found)
       found = .false.
     end select
     !
+    ! -- Return
     return
   end subroutine mwt_bd_obs
 
+  !> @brief Sets the stress period attributes for keyword use.
+  !<
   subroutine mwt_set_stressperiod(this, itemno, keyword, found)
-! ******************************************************************************
-! mwt_set_stressperiod -- Set a stress period attribute for using keywords.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use TimeSeriesManagerModule, only: read_value_or_time_series_adv
     ! -- dummy
     class(GwtMwtType), intent(inout) :: this
@@ -957,7 +899,6 @@ subroutine mwt_set_stressperiod(this, itemno, keyword, found)
     integer(I4B) :: jj
     real(DP), pointer :: bndElem => null()
     ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! RATE <rate>
     !
@@ -982,7 +923,7 @@ subroutine mwt_set_stressperiod(this, itemno, keyword, found)
     !
 999 continue
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine mwt_set_stressperiod
 
diff --git a/src/Model/GroundWaterTransport/gwt1sft1.f90 b/src/Model/GroundWaterTransport/gwt1sft1.f90
index fe310f5eb42..fc6ffafc171 100644
--- a/src/Model/GroundWaterTransport/gwt1sft1.f90
+++ b/src/Model/GroundWaterTransport/gwt1sft1.f90
@@ -36,10 +36,10 @@ module GwtSftModule
   use ConstantsModule, only: DZERO, DONE, LINELENGTH
   use SimModule, only: store_error
   use BndModule, only: BndType, GetBndFromList
-  use GwtFmiModule, only: GwtFmiType
+  use TspFmiModule, only: TspFmiType
   use SfrModule, only: SfrType
   use ObserveModule, only: ObserveType
-  use GwtAptModule, only: GwtAptType, apt_process_obsID, &
+  use TspAptModule, only: TspAptType, apt_process_obsID, &
                           apt_process_obsID12
   use MatrixBaseModule
 
@@ -51,7 +51,7 @@ module GwtSftModule
   character(len=*), parameter :: flowtype = 'SFR'
   character(len=16) :: text = '             SFT'
 
-  type, extends(GwtAptType) :: GwtSftType
+  type, extends(TspAptType) :: GwtSftType
 
     integer(I4B), pointer :: idxbudrain => null() ! index of rainfall terms in flowbudptr
     integer(I4B), pointer :: idxbudevap => null() ! index of evaporation terms in flowbudptr
@@ -89,14 +89,10 @@ module GwtSftModule
 
 contains
 
+  !> @brief Create a new sft package
+  !<
   subroutine sft_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
-                        fmi)
-! ******************************************************************************
-! sft_create -- Create a New SFT Package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+                        fmi, eqnsclfac, dvt, dvu, dvua)
     ! -- dummy
     class(BndType), pointer :: packobj
     integer(I4B), intent(in) :: id
@@ -105,10 +101,13 @@ subroutine sft_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
     integer(I4B), intent(in) :: iout
     character(len=*), intent(in) :: namemodel
     character(len=*), intent(in) :: pakname
-    type(GwtFmiType), pointer :: fmi
+    type(TspFmiType), pointer :: fmi
+    real(DP), intent(in), pointer :: eqnsclfac !< governing equation scale factor
+    character(len=*), intent(in) :: dvt !< For GWT, set to "CONCENTRATION" in TspAptType
+    character(len=*), intent(in) :: dvu !< For GWT, set to "mass" in TspAptType
+    character(len=*), intent(in) :: dvua !< For GWT, set to "M" in TspAptType
     ! -- local
     type(GwtSftType), pointer :: sftobj
-! ------------------------------------------------------------------------------
     !
     ! -- allocate the object and assign values to object variables
     allocate (sftobj)
@@ -123,30 +122,34 @@ subroutine sft_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
     !
     ! -- initialize package
     call packobj%pack_initialize()
-
+    !
     packobj%inunit = inunit
     packobj%iout = iout
     packobj%id = id
     packobj%ibcnum = ibcnum
     packobj%ncolbnd = 1
     packobj%iscloc = 1
-
+    !
     ! -- Store pointer to flow model interface.  When the GwfGwt exchange is
     !    created, it sets fmi%bndlist so that the GWT model has access to all
     !    the flow packages
     sftobj%fmi => fmi
     !
-    ! -- return
+    ! -- Store pointer to governing equation scale factor
+    sftobj%eqnsclfac => eqnsclfac
+    !
+    ! -- Set labels that will be used in generalized APT class
+    sftobj%depvartype = dvt
+    sftobj%depvarunit = dvu
+    sftobj%depvarunitabbrev = dvua
+    !
+    ! -- Return
     return
   end subroutine sft_create
 
+  !> @brief Find corresponding sft package
+  !<
   subroutine find_sft_package(this)
-! ******************************************************************************
-! find corresponding sft package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
@@ -157,7 +160,6 @@ subroutine find_sft_package(this)
     integer(I4B) :: ip, icount
     integer(I4B) :: nbudterm
     logical :: found
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize found to false, and error later if flow package cannot
     !    be found
@@ -264,14 +266,12 @@ subroutine find_sft_package(this)
     return
   end subroutine find_sft_package
 
+  !> @brief Add matrix terms related to SFT
+  !!
+  !! This will be called from TspAptType%apt_fc_expanded()
+  !! in order to add matrix terms specifically for SFT
+  !<
   subroutine sft_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
-! ******************************************************************************
-! sft_fc_expanded -- this will be called from GwtAptType%apt_fc_expanded()
-!   in order to add matrix terms specifically for SFT
-! ****************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtSftType) :: this
@@ -286,7 +286,6 @@ subroutine sft_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
     real(DP) :: rrate
     real(DP) :: rhsval
     real(DP) :: hcofval
-! ------------------------------------------------------------------------------
     !
     ! -- add rainfall contribution
     if (this%idxbudrain /= 0) then
@@ -347,20 +346,15 @@ subroutine sft_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
     return
   end subroutine sft_fc_expanded
 
+  !> @brief Add terms specific to sft to the explicit sft solve
+  !<
   subroutine sft_solve(this)
-! ******************************************************************************
-! sft_solve -- add terms specific to sfr to the explicit sfr solve
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtSftType) :: this
     ! -- local
     integer(I4B) :: j
     integer(I4B) :: n1, n2
     real(DP) :: rrate
-! ------------------------------------------------------------------------------
     !
     ! -- add rainfall contribution
     if (this%idxbudrain /= 0) then
@@ -406,36 +400,28 @@ subroutine sft_solve(this)
     return
   end subroutine sft_solve
 
+  !> @brief Function to return the number of budget terms just for this package.
+  !!
+  !! This overrides a function in the parent class.
+  !<
   function sft_get_nbudterms(this) result(nbudterms)
-! ******************************************************************************
-! sft_get_nbudterms -- function to return the number of budget terms just for
-!   this package.  This overrides function in parent.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtSftType) :: this
     ! -- return
     integer(I4B) :: nbudterms
     ! -- local
-! ------------------------------------------------------------------------------
     !
-    ! -- Number of budget terms is 6
+    ! -- Number of budget terms is 5
     nbudterms = 5
     !
     ! -- Return
     return
   end function sft_get_nbudterms
 
+  !> @brief Set up the budget object that stores all the sft flows
+  !<
   subroutine sft_setup_budobj(this, idx)
-! ******************************************************************************
-! sft_setup_budobj -- Set up the budget object that stores all the sfr flows
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LENBUDTXT
     ! -- dummy
@@ -444,7 +430,6 @@ subroutine sft_setup_budobj(this, idx)
     ! -- local
     integer(I4B) :: maxlist, naux
     character(len=LENBUDTXT) :: text
-! ------------------------------------------------------------------------------
     !
     ! --
     text = '        RAINFALL'
@@ -515,13 +500,9 @@ subroutine sft_setup_budobj(this, idx)
     return
   end subroutine sft_setup_budobj
 
+  !> @brief Copy flow terms into this%budobj
+  !<
   subroutine sft_fill_budobj(this, idx, x, ccratin, ccratout)
-! ******************************************************************************
-! sft_fill_budobj -- copy flow terms into this%budobj
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtSftType) :: this
@@ -534,8 +515,7 @@ subroutine sft_fill_budobj(this, idx, x, ccratin, ccratout)
     integer(I4B) :: nlist
     real(DP) :: q
     ! -- formats
-! -----------------------------------------------------------------------------
-
+    !
     ! -- RAIN
     idx = idx + 1
     nlist = this%flowbudptr%budterm(this%idxbudrain)%nlist
@@ -545,7 +525,7 @@ subroutine sft_fill_budobj(this, idx, x, ccratin, ccratout)
       call this%budobj%budterm(idx)%update_term(n1, n2, q)
       call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
     end do
-
+    !
     ! -- EVAPORATION
     idx = idx + 1
     nlist = this%flowbudptr%budterm(this%idxbudevap)%nlist
@@ -555,7 +535,7 @@ subroutine sft_fill_budobj(this, idx, x, ccratin, ccratout)
       call this%budobj%budterm(idx)%update_term(n1, n2, q)
       call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
     end do
-
+    !
     ! -- RUNOFF
     idx = idx + 1
     nlist = this%flowbudptr%budterm(this%idxbudroff)%nlist
@@ -565,7 +545,7 @@ subroutine sft_fill_budobj(this, idx, x, ccratin, ccratout)
       call this%budobj%budterm(idx)%update_term(n1, n2, q)
       call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
     end do
-
+    !
     ! -- EXT-INFLOW
     idx = idx + 1
     nlist = this%flowbudptr%budterm(this%idxbudiflw)%nlist
@@ -575,7 +555,7 @@ subroutine sft_fill_budobj(this, idx, x, ccratin, ccratout)
       call this%budobj%budterm(idx)%update_term(n1, n2, q)
       call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
     end do
-
+    !
     ! -- EXT-OUTFLOW
     idx = idx + 1
     nlist = this%flowbudptr%budterm(this%idxbudoutf)%nlist
@@ -585,28 +565,23 @@ subroutine sft_fill_budobj(this, idx, x, ccratin, ccratout)
       call this%budobj%budterm(idx)%update_term(n1, n2, q)
       call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
     end do
-
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine sft_fill_budobj
 
+  !> @brief Allocate scalars specific to the streamflow energy transport (SFE)
+  !! package.
+  !<
   subroutine allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwtSftType) :: this
     ! -- local
-! ------------------------------------------------------------------------------
     !
-    ! -- allocate scalars in GwtAptType
-    call this%GwtAptType%allocate_scalars()
+    ! -- allocate scalars in TspAptType
+    call this%TspAptType%allocate_scalars()
     !
     ! -- Allocate
     call mem_allocate(this%idxbudrain, 'IDXBUDRAIN', this%memoryPath)
@@ -626,20 +601,16 @@ subroutine allocate_scalars(this)
     return
   end subroutine allocate_scalars
 
+  !> @brief Allocate arrays specific to the streamflow energy transport (SFE)
+  !! package.
+  !<
   subroutine sft_allocate_arrays(this)
-! ******************************************************************************
-! sft_allocate_arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwtSftType), intent(inout) :: this
     ! -- local
     integer(I4B) :: n
-! ------------------------------------------------------------------------------
     !
     ! -- time series
     call mem_allocate(this%concrain, this%ncv, 'CONCRAIN', this%memoryPath)
@@ -647,8 +618,8 @@ subroutine sft_allocate_arrays(this)
     call mem_allocate(this%concroff, this%ncv, 'CONCROFF', this%memoryPath)
     call mem_allocate(this%conciflw, this%ncv, 'CONCIFLW', this%memoryPath)
     !
-    ! -- call standard GwtApttype allocate arrays
-    call this%GwtAptType%apt_allocate_arrays()
+    ! -- call standard TspAptType allocate arrays
+    call this%TspAptType%apt_allocate_arrays()
     !
     ! -- Initialize
     do n = 1, this%ncv
@@ -658,24 +629,18 @@ subroutine sft_allocate_arrays(this)
       this%conciflw(n) = DZERO
     end do
     !
-    !
     ! -- Return
     return
   end subroutine sft_allocate_arrays
 
+  !> @brief Deallocate memory
+  !<
   subroutine sft_da(this)
-! ******************************************************************************
-! sft_da
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(GwtSftType) :: this
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- deallocate scalars
     call mem_deallocate(this%idxbudrain)
@@ -690,21 +655,17 @@ subroutine sft_da(this)
     call mem_deallocate(this%concroff)
     call mem_deallocate(this%conciflw)
     !
-    ! -- deallocate scalars in GwtAptType
-    call this%GwtAptType%bnd_da()
+    ! -- deallocate scalars in TspAptType
+    call this%TspAptType%bnd_da()
     !
     ! -- Return
     return
   end subroutine sft_da
 
+  !> @brief Rain term
+  !<
   subroutine sft_rain_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! sft_rain_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtSftType) :: this
     integer(I4B), intent(in) :: ientry
@@ -716,7 +677,7 @@ subroutine sft_rain_term(this, ientry, n1, n2, rrate, &
     ! -- local
     real(DP) :: qbnd
     real(DP) :: ctmp
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudrain)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudrain)%id2(ientry)
     qbnd = this%flowbudptr%budterm(this%idxbudrain)%flow(ientry)
@@ -725,18 +686,14 @@ subroutine sft_rain_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = -rrate
     if (present(hcofval)) hcofval = DZERO
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine sft_rain_term
 
+  !> @brief Evaporative term
+  !<
   subroutine sft_evap_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! sft_evap_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtSftType) :: this
     integer(I4B), intent(in) :: ientry
@@ -749,7 +706,7 @@ subroutine sft_evap_term(this, ientry, n1, n2, rrate, &
     real(DP) :: qbnd
     real(DP) :: ctmp
     real(DP) :: omega
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudevap)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudevap)%id2(ientry)
     ! -- note that qbnd is negative for evap
@@ -766,18 +723,14 @@ subroutine sft_evap_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = -(DONE - omega) * qbnd * ctmp
     if (present(hcofval)) hcofval = omega * qbnd
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine sft_evap_term
 
+  !> @brief Runoff term
+  !<
   subroutine sft_roff_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! sft_roff_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtSftType) :: this
     integer(I4B), intent(in) :: ientry
@@ -789,7 +742,7 @@ subroutine sft_roff_term(this, ientry, n1, n2, rrate, &
     ! -- local
     real(DP) :: qbnd
     real(DP) :: ctmp
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudroff)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudroff)%id2(ientry)
     qbnd = this%flowbudptr%budterm(this%idxbudroff)%flow(ientry)
@@ -798,18 +751,18 @@ subroutine sft_roff_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = -rrate
     if (present(hcofval)) hcofval = DZERO
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine sft_roff_term
 
+  !> @brief Inflow Term
+  !!
+  !! Accounts for mass added via streamflow entering into a stream channel;
+  !! for example, energy entering the model domain via a specified flow in a
+  !! stream channel.
+  !<
   subroutine sft_iflw_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! sft_iflw_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtSftType) :: this
     integer(I4B), intent(in) :: ientry
@@ -821,7 +774,7 @@ subroutine sft_iflw_term(this, ientry, n1, n2, rrate, &
     ! -- local
     real(DP) :: qbnd
     real(DP) :: ctmp
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudiflw)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudiflw)%id2(ientry)
     qbnd = this%flowbudptr%budterm(this%idxbudiflw)%flow(ientry)
@@ -830,18 +783,17 @@ subroutine sft_iflw_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = -rrate
     if (present(hcofval)) hcofval = DZERO
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine sft_iflw_term
 
+  !> @brief Outflow term
+  !!
+  !! Accounts for the mass leaving a stream channel; for example, mass exiting the
+  !! model domain via a flow in a stream channel flowing out of the active domain.
+  !<
   subroutine sft_outf_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! sft_outf_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtSftType) :: this
     integer(I4B), intent(in) :: ientry
@@ -853,7 +805,7 @@ subroutine sft_outf_term(this, ientry, n1, n2, rrate, &
     ! -- local
     real(DP) :: qbnd
     real(DP) :: ctmp
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudoutf)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudoutf)%id2(ientry)
     qbnd = this%flowbudptr%budterm(this%idxbudoutf)%flow(ientry)
@@ -862,25 +814,21 @@ subroutine sft_outf_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = DZERO
     if (present(hcofval)) hcofval = qbnd
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine sft_outf_term
 
+  !> @brief Observations
+  !!
+  !! Store the observation type supported by the APT package and overide
+  !! BndType%bnd_df_obs
+  !<
   subroutine sft_df_obs(this)
-! ******************************************************************************
-! sft_df_obs -- obs are supported?
-!   -- Store observation type supported by APT package.
-!   -- Overrides BndType%bnd_df_obs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtSftType) :: this
     ! -- local
     integer(I4B) :: indx
-! ------------------------------------------------------------------------------
     !
     ! -- Store obs type and assign procedure pointer
     !    for concentration observation type.
@@ -942,13 +890,13 @@ subroutine sft_df_obs(this)
     call this%obs%StoreObsType('ext-outflow', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => apt_process_obsID
     !
+    ! -- Return
     return
   end subroutine sft_df_obs
 
   !> @brief Process package specific obs
-    !!
-    !! Method to process specific observations for this package.
-    !!
+  !!
+  !! Method to process specific observations for this package.
   !<
   subroutine sft_rp_obs(this, obsrv, found)
     ! -- dummy
@@ -975,16 +923,13 @@ subroutine sft_rp_obs(this, obsrv, found)
       found = .false.
     end select
     !
+    ! -- Return
     return
   end subroutine sft_rp_obs
 
+  !> @brief Calculate observation value and pass it back to APT
+  !<
   subroutine sft_bd_obs(this, obstypeid, jj, v, found)
-! ******************************************************************************
-! sft_bd_obs -- calculate observation value and pass it back to APT
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtSftType), intent(inout) :: this
     character(len=*), intent(in) :: obstypeid
@@ -993,7 +938,6 @@ subroutine sft_bd_obs(this, obstypeid, jj, v, found)
     logical, intent(inout) :: found
     ! -- local
     integer(I4B) :: n1, n2
-! ------------------------------------------------------------------------------
     !
     found = .true.
     select case (obstypeid)
@@ -1021,16 +965,13 @@ subroutine sft_bd_obs(this, obstypeid, jj, v, found)
       found = .false.
     end select
     !
+    ! -- Return
     return
   end subroutine sft_bd_obs
 
+  !> @brief Sets the stress period attributes for keyword use.
+  !<
   subroutine sft_set_stressperiod(this, itemno, keyword, found)
-! ******************************************************************************
-! sft_set_stressperiod -- Set a stress period attribute for using keywords.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use TimeSeriesManagerModule, only: read_value_or_time_series_adv
     ! -- dummy
     class(GwtSftType), intent(inout) :: this
@@ -1043,7 +984,6 @@ subroutine sft_set_stressperiod(this, itemno, keyword, found)
     integer(I4B) :: jj
     real(DP), pointer :: bndElem => null()
     ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! RAINFALL <rainfall>
     ! EVAPORATION <evaporation>
@@ -1105,7 +1045,7 @@ subroutine sft_set_stressperiod(this, itemno, keyword, found)
     !
 999 continue
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine sft_set_stressperiod
 
diff --git a/src/Model/GroundWaterTransport/gwt1src1.f90 b/src/Model/GroundWaterTransport/gwt1src1.f90
index 1565c40ef09..0314413ce72 100644
--- a/src/Model/GroundWaterTransport/gwt1src1.f90
+++ b/src/Model/GroundWaterTransport/gwt1src1.f90
@@ -1,7 +1,7 @@
 module GwtSrcModule
   !
   use KindModule, only: DP, I4B
-  use ConstantsModule, only: DZERO, DEM1, DONE, LENFTYPE
+  use ConstantsModule, only: DZERO, DEM1, DONE, LENFTYPE, LENVARNAME
   use BndModule, only: BndType
   use ObsModule, only: DefaultObsIdProcessor
   use TimeSeriesLinkModule, only: TimeSeriesLinkType, &
@@ -18,7 +18,11 @@ module GwtSrcModule
   character(len=16) :: text = '             SRC'
   !
   type, extends(BndType) :: GwtSrcType
+
+    character(len=LENVARNAME) :: depvartype = '' !< stores string of dependent variable type, depending on model type
+
   contains
+
     procedure :: allocate_scalars => src_allocate_scalars
     procedure :: bnd_cf => src_cf
     procedure :: bnd_fc => src_fc
@@ -29,19 +33,17 @@ module GwtSrcModule
     procedure, public :: bnd_df_obs => src_df_obs
     ! -- methods for time series
     procedure, public :: bnd_rp_ts => src_rp_ts
+
   end type GwtSrcType
 
 contains
 
-  subroutine src_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
-! ******************************************************************************
-! src_create -- Create a New Src Package
-! Subroutine: (1) create new-style package
-!             (2) point bndobj to the new package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Create a source loading package
+  !!
+  !! This subroutine points bndobj to the newly created package
+  !<
+  subroutine src_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
+                        depvartype)
     ! -- dummy
     class(BndType), pointer :: packobj
     integer(I4B), intent(in) :: id
@@ -50,9 +52,9 @@ subroutine src_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     integer(I4B), intent(in) :: iout
     character(len=*), intent(in) :: namemodel
     character(len=*), intent(in) :: pakname
+    character(len=LENVARNAME), intent(in) :: depvartype
     ! -- local
     type(GwtSrcType), pointer :: srcobj
-! ------------------------------------------------------------------------------
     !
     ! -- allocate the object and assign values to object variables
     allocate (srcobj)
@@ -75,43 +77,38 @@ subroutine src_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname)
     packobj%ncolbnd = 1
     packobj%iscloc = 1
     !
+    ! -- Store the appropriate label based on the dependent variable
+    srcobj%depvartype = depvartype
+    !
     ! -- return
     return
   end subroutine src_create
 
+  !> @brief Deallocate memory
+  !<
   subroutine src_da(this)
-! ******************************************************************************
-! src_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(GwtSrcType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Deallocate parent package
     call this%BndType%bnd_da()
     !
     ! -- scalars
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine src_da
 
+  !> @brief Allocate scalars
+  !!
+  !! Allocate scalars specific to this source loading package
+  !<
   subroutine src_allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars -- allocate scalar members
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwtSrcType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- call standard BndType allocate scalars
     call this%BndType%allocate_scalars()
@@ -120,38 +117,26 @@ subroutine src_allocate_scalars(this)
     !
     ! -- Set values
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine src_allocate_scalars
 
-  subroutine src_cf(this, reset_mover)
-! ******************************************************************************
-! src_cf -- Formulate the HCOF and RHS terms
-! Subroutine: (1) skip if no sources
-!             (2) calculate hcof and rhs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Formulate the HCOF and RHS terms
+  !!
+  !! This subroutine:
+  !!   - calculates hcof and rhs terms
+  !!   - skip if no sources
+  !<
+  subroutine src_cf(this)
     ! -- dummy
     class(GwtSrcType) :: this
-    logical, intent(in), optional :: reset_mover
     ! -- local
     integer(I4B) :: i, node
     real(DP) :: q
-    logical :: lrm
-! ------------------------------------------------------------------------------
     !
     ! -- Return if no sources
     if (this%nbound == 0) return
     !
-    ! -- pakmvrobj cf
-    lrm = .true.
-    if (present(reset_mover)) lrm = reset_mover
-    if (this%imover == 1 .and. lrm) then
-      call this%pakmvrobj%cf()
-    end if
-    !
     ! -- Calculate hcof and rhs for each source entry
     do i = 1, this%nbound
       node = this%nodelist(i)
@@ -164,16 +149,15 @@ subroutine src_cf(this, reset_mover)
       this%rhs(i) = -q
     end do
     !
+    ! -- Return
     return
   end subroutine src_cf
 
+  !> @brief Add matrix terms related to specified mass source loading
+  !!
+  !! Copy rhs and hcof into solution rhs and amat
+  !<
   subroutine src_fc(this, rhs, ia, idxglo, matrix_sln)
-! **************************************************************************
-! src_fc -- Copy rhs and hcof into solution rhs and amat
-! **************************************************************************
-!
-!    SPECIFICATIONS:
-! --------------------------------------------------------------------------
     ! -- dummy
     class(GwtSrcType) :: this
     real(DP), dimension(:), intent(inout) :: rhs
@@ -182,7 +166,6 @@ subroutine src_fc(this, rhs, ia, idxglo, matrix_sln)
     class(MatrixBaseType), pointer :: matrix_sln
     ! -- local
     integer(I4B) :: i, n, ipos
-! --------------------------------------------------------------------------
     !
     ! -- pakmvrobj fc
     if (this%imover == 1) then
@@ -203,20 +186,19 @@ subroutine src_fc(this, rhs, ia, idxglo, matrix_sln)
       end if
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine src_fc
 
+  !> @brief Define list labels
+  !!
+  !! Define the list heading that is written to iout when PRINT_INPUT
+  !! option is used.
+  !<
   subroutine define_listlabel(this)
-! ******************************************************************************
-! define_listlabel -- Define the list heading that is written to iout when
-!   PRINT_INPUT option is used.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     class(GwtSrcType), intent(inout) :: this
-! ------------------------------------------------------------------------------
+    ! -- local
     !
     ! -- create the header list label
     this%listlabel = trim(this%filtyp)//' NO.'
@@ -235,42 +217,41 @@ subroutine define_listlabel(this)
       write (this%listlabel, '(a, a16)') trim(this%listlabel), 'BOUNDARY NAME'
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine define_listlabel
 
   ! -- Procedures related to observations
+  !> @brief Support function for specified mass source loading observations
+  !!
+  !! This function:
+  !!   - returns true because SRC package supports observations.
+  !!   - overrides BndType%bnd_obs_supported()
+  !<
   logical function src_obs_supported(this)
-    ! ******************************************************************************
-    ! src_obs_supported
-    !   -- Return true because SRC package supports observations.
-    !   -- Overrides BndType%bnd_obs_supported()
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
     implicit none
+    ! -- dummy
     class(GwtSrcType) :: this
-    ! ------------------------------------------------------------------------------
+    !
     src_obs_supported = .true.
+    !
+    ! -- Return
     return
   end function src_obs_supported
 
+  !> @brief Define observations
+  !!
+  !! This subroutine:
+  !!   - stores observation types supported by SRC package.
+  !!   - overrides BndType%bnd_df_obs
+  !<
   subroutine src_df_obs(this)
-    ! ******************************************************************************
-    ! src_df_obs (implements bnd_df_obs)
-    !   -- Store observation type supported by SRC package.
-    !   -- Overrides BndType%bnd_df_obs
-    ! ******************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------------
     implicit none
     ! -- dummy
     class(GwtSrcType) :: this
     ! -- local
     integer(I4B) :: indx
-    ! ------------------------------------------------------------------------------
+    !
     call this%obs%StoreObsType('src', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => DefaultObsIdProcessor
     !
@@ -279,17 +260,17 @@ subroutine src_df_obs(this)
     call this%obs%StoreObsType('to-mvr', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => DefaultObsIdProcessor
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine src_df_obs
 
-  ! -- Procedure related to time series
-
+  !> @brief Procedure related to time series
+  !!
+  !! Assign tsLink%Text appropriately for all time series in use by package.
+  !! In the SRC package only the SMASSRATE variable can be controlled by time
+  !! series.
+  !<
   subroutine src_rp_ts(this)
-    ! -- Assign tsLink%Text appropriately for
-    !    all time series in use by package.
-    !    In the SRC package only the SMASSRATE variable
-    !    can be controlled by time series.
     ! -- dummy
     class(GwtSrcType), intent(inout) :: this
     ! -- local
@@ -306,6 +287,7 @@ subroutine src_rp_ts(this)
       end if
     end do
     !
+    ! -- Return
     return
   end subroutine src_rp_ts
 
diff --git a/src/Model/GroundWaterTransport/gwt1uzt1.f90 b/src/Model/GroundWaterTransport/gwt1uzt1.f90
index c6be55aec38..4006062fb28 100644
--- a/src/Model/GroundWaterTransport/gwt1uzt1.f90
+++ b/src/Model/GroundWaterTransport/gwt1uzt1.f90
@@ -30,10 +30,10 @@ module GwtUztModule
   use ConstantsModule, only: DZERO, DONE, LINELENGTH
   use SimModule, only: store_error
   use BndModule, only: BndType, GetBndFromList
-  use GwtFmiModule, only: GwtFmiType
+  use TspFmiModule, only: TspFmiType
   use UzfModule, only: UzfType
   use ObserveModule, only: ObserveType
-  use GwtAptModule, only: GwtAptType, apt_process_obsID, &
+  use TspAptModule, only: TspAptType, apt_process_obsID, &
                           apt_process_obsID12
   use MatrixBaseModule
   implicit none
@@ -44,7 +44,7 @@ module GwtUztModule
   character(len=*), parameter :: flowtype = 'UZF'
   character(len=16) :: text = '             UZT'
 
-  type, extends(GwtAptType) :: GwtUztType
+  type, extends(TspAptType) :: GwtUztType
 
     integer(I4B), pointer :: idxbudinfl => null() ! index of uzf infiltration terms in flowbudptr
     integer(I4B), pointer :: idxbudrinf => null() ! index of rejected infiltration terms in flowbudptr
@@ -77,14 +77,10 @@ module GwtUztModule
 
 contains
 
+  !> @brief Create a new UZT package
+  !<
   subroutine uzt_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
-                        fmi)
-! ******************************************************************************
-! uzt_create -- Create a New UZT Package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+                        fmi, eqnsclfac, dvt, dvu, dvua)
     ! -- dummy
     class(BndType), pointer :: packobj
     integer(I4B), intent(in) :: id
@@ -93,10 +89,13 @@ subroutine uzt_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
     integer(I4B), intent(in) :: iout
     character(len=*), intent(in) :: namemodel
     character(len=*), intent(in) :: pakname
-    type(GwtFmiType), pointer :: fmi
+    type(TspFmiType), pointer :: fmi
+    real(DP), intent(in), pointer :: eqnsclfac !< governing equation scale factor
+    character(len=*), intent(in) :: dvt !< For GWT, set to "CONCENTRATION" in TspAptType
+    character(len=*), intent(in) :: dvu !< For GWT, set to "mass" in TspAptType
+    character(len=*), intent(in) :: dvua !< For GWT, set to "M" in TspAptType
     ! -- local
     type(GwtUztType), pointer :: uztobj
-! ------------------------------------------------------------------------------
     !
     ! -- allocate the object and assign values to object variables
     allocate (uztobj)
@@ -111,30 +110,34 @@ subroutine uzt_create(packobj, id, ibcnum, inunit, iout, namemodel, pakname, &
     !
     ! -- initialize package
     call packobj%pack_initialize()
-
+    !
     packobj%inunit = inunit
     packobj%iout = iout
     packobj%id = id
     packobj%ibcnum = ibcnum
     packobj%ncolbnd = 1
     packobj%iscloc = 1
-
+    !
     ! -- Store pointer to flow model interface.  When the GwfGwt exchange is
     !    created, it sets fmi%bndlist so that the GWT model has access to all
     !    the flow packages
     uztobj%fmi => fmi
     !
-    ! -- return
+    ! -- Store pointer to governing equation scale factor
+    uztobj%eqnsclfac => eqnsclfac
+    !
+    ! -- Set labels that will be used in generalized APT class
+    uztobj%depvartype = dvt
+    uztobj%depvarunit = dvu
+    uztobj%depvarunitabbrev = dvua
+    !
+    ! -- Return
     return
   end subroutine uzt_create
 
+  !> @brief Find corresponding uzt package
+  !<
   subroutine find_uzt_package(this)
-! ******************************************************************************
-! find corresponding uzt package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
@@ -145,7 +148,6 @@ subroutine find_uzt_package(this)
     integer(I4B) :: ip, icount
     integer(I4B) :: nbudterm
     logical :: found
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize found to false, and error later if flow package cannot
     !    be found
@@ -249,14 +251,12 @@ subroutine find_uzt_package(this)
     return
   end subroutine find_uzt_package
 
+  !> @brief Add matrix terms related to UZT
+  !!
+  !! This will be called from TspAptType%apt_fc_expanded()
+  !! in order to add matrix terms specifically for this package
+  !<
   subroutine uzt_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
-! ******************************************************************************
-! uzt_fc_expanded -- this will be called from GwtAptType%apt_fc_expanded()
-!   in order to add matrix terms specifically for this package
-! ****************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtUztType) :: this
@@ -271,7 +271,6 @@ subroutine uzt_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
     real(DP) :: rrate
     real(DP) :: rhsval
     real(DP) :: hcofval
-! ------------------------------------------------------------------------------
     !
     ! -- add infiltration contribution
     if (this%idxbudinfl /= 0) then
@@ -321,21 +320,17 @@ subroutine uzt_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
     return
   end subroutine uzt_fc_expanded
 
+  !> @brief Explicit solve
+  !!
+  !! Add terms specific to the unsaturated zone to the explicit unsaturated-
+  !! zone solve
   subroutine uzt_solve(this)
-! ******************************************************************************
-! uzt_solve -- add terms specific to the unsaturated zone to the explicit
-!              unsaturated-zone solve
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtUztType) :: this
     ! -- local
     integer(I4B) :: j
     integer(I4B) :: n1, n2
     real(DP) :: rrate
-! ------------------------------------------------------------------------------
     !
     ! -- add infiltration contribution
     if (this%idxbudinfl /= 0) then
@@ -373,21 +368,17 @@ subroutine uzt_solve(this)
     return
   end subroutine uzt_solve
 
+  !> @brief Function that returns the number of budget terms for this package
+  !!
+  !! This overrides function in parent.
+  !<
   function uzt_get_nbudterms(this) result(nbudterms)
-! ******************************************************************************
-! uzt_get_nbudterms -- function to return the number of budget terms just for
-!   this package.  This overrides function in parent.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtUztType) :: this
     ! -- return
     integer(I4B) :: nbudterms
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- Number of budget terms is 4
     nbudterms = 0
@@ -400,14 +391,9 @@ function uzt_get_nbudterms(this) result(nbudterms)
     return
   end function uzt_get_nbudterms
 
+  !> @brief Set up the budget object that stores all the unsaturated-zone flows
+  !<
   subroutine uzt_setup_budobj(this, idx)
-! ******************************************************************************
-! uzt_setup_budobj -- Set up the budget object that stores all the unsaturated-
-!                     zone flows
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LENBUDTXT
     ! -- dummy
@@ -416,9 +402,8 @@ subroutine uzt_setup_budobj(this, idx)
     ! -- local
     integer(I4B) :: maxlist, naux
     character(len=LENBUDTXT) :: text
-! ------------------------------------------------------------------------------
     !
-    ! --
+    ! -- Infiltration flux
     text = '    INFILTRATION'
     idx = idx + 1
     maxlist = this%flowbudptr%budterm(this%idxbudinfl)%maxlist
@@ -430,9 +415,8 @@ subroutine uzt_setup_budobj(this, idx)
                                              this%packName, &
                                              maxlist, .false., .false., &
                                              naux)
-
     !
-    ! --
+    ! -- Rejected infiltration flux (and subsequently removed from the model)
     if (this%idxbudrinf /= 0) then
       text = '         REJ-INF'
       idx = idx + 1
@@ -446,9 +430,8 @@ subroutine uzt_setup_budobj(this, idx)
                                                maxlist, .false., .false., &
                                                naux)
     end if
-
     !
-    ! --
+    ! -- Evapotranspiration flux originating from the unsaturated zone
     if (this%idxbuduzet /= 0) then
       text = '            UZET'
       idx = idx + 1
@@ -462,9 +445,8 @@ subroutine uzt_setup_budobj(this, idx)
                                                maxlist, .false., .false., &
                                                naux)
     end if
-
     !
-    ! --
+    ! -- Rejected infiltration flux that is transferred to the MVR/MVT packages
     if (this%idxbudritm /= 0) then
       text = '  INF-REJ-TO-MVR'
       idx = idx + 1
@@ -478,19 +460,13 @@ subroutine uzt_setup_budobj(this, idx)
                                                maxlist, .false., .false., &
                                                naux)
     end if
-
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzt_setup_budobj
 
+  !> @brief Copy flow terms into this%budobj
   subroutine uzt_fill_budobj(this, idx, x, ccratin, ccratout)
-! ******************************************************************************
-! uzt_fill_budobj -- copy flow terms into this%budobj
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtUztType) :: this
@@ -503,8 +479,7 @@ subroutine uzt_fill_budobj(this, idx, x, ccratin, ccratout)
     integer(I4B) :: nlist
     real(DP) :: q
     ! -- formats
-! -----------------------------------------------------------------------------
-
+    !
     ! -- INFILTRATION
     idx = idx + 1
     nlist = this%flowbudptr%budterm(this%idxbudinfl)%nlist
@@ -514,7 +489,7 @@ subroutine uzt_fill_budobj(this, idx, x, ccratin, ccratout)
       call this%budobj%budterm(idx)%update_term(n1, n2, q)
       call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
     end do
-
+    !
     ! -- REJ-INF
     if (this%idxbudrinf /= 0) then
       idx = idx + 1
@@ -526,7 +501,7 @@ subroutine uzt_fill_budobj(this, idx, x, ccratin, ccratout)
         call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
       end do
     end if
-
+    !
     ! -- UZET
     if (this%idxbuduzet /= 0) then
       idx = idx + 1
@@ -538,7 +513,7 @@ subroutine uzt_fill_budobj(this, idx, x, ccratin, ccratout)
         call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
       end do
     end if
-
+    !
     ! -- REJ-INF-TO-MVR
     if (this%idxbudritm /= 0) then
       idx = idx + 1
@@ -550,28 +525,24 @@ subroutine uzt_fill_budobj(this, idx, x, ccratin, ccratout)
         call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
       end do
     end if
-
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzt_fill_budobj
 
+  !> @brief Allocate scalar variables for package
+  !!
+  !!  Method to allocate scalar variables for the package.
+  !<
   subroutine allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwtUztType) :: this
     ! -- local
-! ------------------------------------------------------------------------------
     !
-    ! -- allocate scalars in GwtAptType
-    call this%GwtAptType%allocate_scalars()
+    ! -- allocate scalars in TspAptType
+    call this%TspAptType%allocate_scalars()
     !
     ! -- Allocate
     call mem_allocate(this%idxbudinfl, 'IDXBUDINFL', this%memoryPath)
@@ -589,27 +560,24 @@ subroutine allocate_scalars(this)
     return
   end subroutine allocate_scalars
 
+  !> @brief Allocate arrays for package
+  !!
+  !!  Method to allocate arrays for the package.
+  !<
   subroutine uzt_allocate_arrays(this)
-! ******************************************************************************
-! uzt_allocate_arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(GwtUztType), intent(inout) :: this
     ! -- local
     integer(I4B) :: n
-! ------------------------------------------------------------------------------
     !
     ! -- time series
     call mem_allocate(this%concinfl, this%ncv, 'CONCINFL', this%memoryPath)
     call mem_allocate(this%concuzet, this%ncv, 'CONCUZET', this%memoryPath)
     !
-    ! -- call standard GwtApttype allocate arrays
-    call this%GwtAptType%apt_allocate_arrays()
+    ! -- call standard TspAptType allocate arrays
+    call this%TspAptType%apt_allocate_arrays()
     !
     ! -- Initialize
     do n = 1, this%ncv
@@ -617,24 +585,20 @@ subroutine uzt_allocate_arrays(this)
       this%concuzet(n) = DZERO
     end do
     !
-    !
     ! -- Return
     return
   end subroutine uzt_allocate_arrays
 
+  !> @brief Deallocate memory
+  !!
+  !!  Method to deallocate memory for the package.
+  !<
   subroutine uzt_da(this)
-! ******************************************************************************
-! uzt_da
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(GwtUztType) :: this
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- deallocate scalars
     call mem_deallocate(this%idxbudinfl)
@@ -646,21 +610,20 @@ subroutine uzt_da(this)
     call mem_deallocate(this%concinfl)
     call mem_deallocate(this%concuzet)
     !
-    ! -- deallocate scalars in GwtAptType
-    call this%GwtAptType%bnd_da()
+    ! -- deallocate scalars in TspAptType
+    call this%TspAptType%bnd_da()
     !
     ! -- Return
     return
   end subroutine uzt_da
 
+  !> @brief Infiltration term
+  !!
+  !! Accounts for mass added to the subsurface via infiltration. For example,
+  !! mass entering the model domain via rainfall or irrigation.
+  !<
   subroutine uzt_infl_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! uzt_infl_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtUztType) :: this
     integer(I4B), intent(in) :: ientry
@@ -673,7 +636,7 @@ subroutine uzt_infl_term(this, ientry, n1, n2, rrate, &
     real(DP) :: qbnd
     real(DP) :: ctmp
     real(DP) :: h, r
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudinfl)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudinfl)%id2(ientry)
     ! -- note that qbnd is negative for negative infiltration
@@ -691,18 +654,19 @@ subroutine uzt_infl_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = r
     if (present(hcofval)) hcofval = h
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzt_infl_term
 
+  !> @brief Rejected infiltration term
+  !!
+  !! Accounts for mass that is added to the model from specifying an
+  !! infiltration rate and concentration, but is subsequently removed from
+  !! the model as that portion of the infiltration that is rejected (and
+  !! NOT transferred to another advanced package via the MVR/MVT packages).
+  !<
   subroutine uzt_rinf_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! uzt_rinf_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtUztType) :: this
     integer(I4B), intent(in) :: ientry
@@ -714,7 +678,7 @@ subroutine uzt_rinf_term(this, ientry, n1, n2, rrate, &
     ! -- local
     real(DP) :: qbnd
     real(DP) :: ctmp
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudrinf)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudrinf)%id2(ientry)
     qbnd = this%flowbudptr%budterm(this%idxbudrinf)%flow(ientry)
@@ -723,18 +687,17 @@ subroutine uzt_rinf_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = DZERO
     if (present(hcofval)) hcofval = qbnd
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzt_rinf_term
 
+  !> @brief Evapotranspiration from the unsaturated-zone term
+  !!
+  !! Accounts for mass removed as a result of evapotranspiration from the
+  !! unsaturated zone.
+  !<
   subroutine uzt_uzet_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! uzt_uzet_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtUztType) :: this
     integer(I4B), intent(in) :: ientry
@@ -747,7 +710,7 @@ subroutine uzt_uzet_term(this, ientry, n1, n2, rrate, &
     real(DP) :: qbnd
     real(DP) :: ctmp
     real(DP) :: omega
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbuduzet)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbuduzet)%id2(ientry)
     ! -- note that qbnd is negative for uzet
@@ -764,18 +727,19 @@ subroutine uzt_uzet_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = -(DONE - omega) * qbnd * ctmp
     if (present(hcofval)) hcofval = omega * qbnd
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzt_uzet_term
 
+  !> @brief Rejected infiltration to MVR/MVT term
+  !!
+  !! Accounts for energy that is added to the model from specifying an
+  !! infiltration rate and temperature, but does not infiltrate into the
+  !! subsurface.  This subroutine is called when the rejected infiltration
+  !! is transferred to another advanced package via the MVR/MVT packages.
+  !<
   subroutine uzt_ritm_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-! ******************************************************************************
-! uzt_ritm_term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtUztType) :: this
     integer(I4B), intent(in) :: ientry
@@ -787,7 +751,7 @@ subroutine uzt_ritm_term(this, ientry, n1, n2, rrate, &
     ! -- local
     real(DP) :: qbnd
     real(DP) :: ctmp
-! ------------------------------------------------------------------------------
+    !
     n1 = this%flowbudptr%budterm(this%idxbudritm)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudritm)%id2(ientry)
     qbnd = this%flowbudptr%budterm(this%idxbudritm)%flow(ientry)
@@ -796,25 +760,22 @@ subroutine uzt_ritm_term(this, ientry, n1, n2, rrate, &
     if (present(rhsval)) rhsval = DZERO
     if (present(hcofval)) hcofval = qbnd
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzt_ritm_term
 
+  !> @brief Define UZT Observation
+  !!
+  !! This subroutine:
+  !!   - Stores observation types supported by the parent APT package.
+  !!   - Overrides BndType%bnd_df_obs
+  !<
   subroutine uzt_df_obs(this)
-! ******************************************************************************
-! uzt_df_obs -- obs are supported?
-!   -- Store observation type supported by APT package.
-!   -- Overrides BndType%bnd_df_obs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
     class(GwtUztType) :: this
     ! -- local
     integer(I4B) :: indx
-! ------------------------------------------------------------------------------
     !
     ! -- Store obs type and assign procedure pointer
     !    for concentration observation type.
@@ -870,13 +831,13 @@ subroutine uzt_df_obs(this)
     call this%obs%StoreObsType('rej-inf-to-mvr', .true., indx)
     this%obs%obsData(indx)%ProcessIdPtr => apt_process_obsID
     !
+    ! -- Return
     return
   end subroutine uzt_df_obs
 
   !> @brief Process package specific obs
-    !!
-    !! Method to process specific observations for this package.
-    !!
+  !!
+  !! Method to process specific observations for this package.
   !<
   subroutine uzt_rp_obs(this, obsrv, found)
     ! -- dummy
@@ -902,13 +863,9 @@ subroutine uzt_rp_obs(this, obsrv, found)
     return
   end subroutine uzt_rp_obs
 
+  !> @brief Calculate observation value and pass it back to APT
+  !<
   subroutine uzt_bd_obs(this, obstypeid, jj, v, found)
-! ******************************************************************************
-! uzt_bd_obs -- calculate observation value and pass it back to APT
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(GwtUztType), intent(inout) :: this
     character(len=*), intent(in) :: obstypeid
@@ -917,7 +874,6 @@ subroutine uzt_bd_obs(this, obstypeid, jj, v, found)
     logical, intent(inout) :: found
     ! -- local
     integer(I4B) :: n1, n2
-! ------------------------------------------------------------------------------
     !
     found = .true.
     select case (obstypeid)
@@ -941,16 +897,13 @@ subroutine uzt_bd_obs(this, obstypeid, jj, v, found)
       found = .false.
     end select
     !
+    ! -- Return
     return
   end subroutine uzt_bd_obs
 
+  !> @brief Sets the stress period attributes for keyword use.
+  !<
   subroutine uzt_set_stressperiod(this, itemno, keyword, found)
-! ******************************************************************************
-! uzt_set_stressperiod -- Set a stress period attribute for using keywords.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use TimeSeriesManagerModule, only: read_value_or_time_series_adv
     ! -- dummy
     class(GwtUztType), intent(inout) :: this
@@ -963,7 +916,6 @@ subroutine uzt_set_stressperiod(this, itemno, keyword, found)
     integer(I4B) :: jj
     real(DP), pointer :: bndElem => null()
     ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! INFILTRATION <infiltration>
     ! UZET <uzet>
@@ -1000,7 +952,7 @@ subroutine uzt_set_stressperiod(this, itemno, keyword, found)
     !
 999 continue
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzt_set_stressperiod
 
diff --git a/src/Model/ModelUtilities/BoundaryPackage.f90 b/src/Model/ModelUtilities/BoundaryPackage.f90
index 1ec95293e16..9bda0f770f8 100644
--- a/src/Model/ModelUtilities/BoundaryPackage.f90
+++ b/src/Model/ModelUtilities/BoundaryPackage.f90
@@ -120,6 +120,7 @@ module BndModule
     procedure :: bnd_rp
     procedure :: bnd_ad
     procedure :: bnd_ck
+    procedure :: bnd_reset
     procedure :: bnd_cf
     procedure :: bnd_fc
     procedure :: bnd_fn
@@ -187,7 +188,7 @@ subroutine bnd_df(this, neq, dis)
     !
     ! -- Create time series managers
     call tsmanager_cr(this%TsManager, this%iout)
-    call tasmanager_cr(this%TasManager, dis, this%iout)
+    call tasmanager_cr(this%TasManager, dis, this%name_model, this%iout)
     !
     ! -- create obs package
     call obs_cr(this%obs, this%inobspkg)
@@ -364,7 +365,8 @@ subroutine bnd_rp(this)
       call this%TasManager%Reset(this%packName)
       !
       ! -- Read data as a list
-      call this%dis%read_list(this%parser%iuactive, this%iout, &
+      call this%dis%read_list(this%parser%line_reader, &
+                              this%parser%iuactive, this%iout, &
                               this%iprpak, nlist, this%inamedbound, &
                               this%iauxmultcol, this%nodelist, &
                               this%bound, this%auxvar, this%auxname, &
@@ -444,6 +446,17 @@ subroutine bnd_ck(this)
     return
   end subroutine bnd_ck
 
+  !> @ brief Reset bnd package before formulating
+  !<
+  subroutine bnd_reset(this)
+    class(BndType) :: this !< BndType object
+
+    if (this%imover == 1) then
+      call this%pakmvrobj%reset()
+    end if
+
+  end subroutine bnd_reset
+
   !> @ brief Formulate the package hcof and rhs terms.
     !!
     !!  Formulate the hcof and rhs terms for the package that will be
@@ -452,10 +465,9 @@ end subroutine bnd_ck
     !!  boundary package.
     !!
   !<
-  subroutine bnd_cf(this, reset_mover)
+  subroutine bnd_cf(this)
     ! -- modules
     class(BndType) :: this !< BndType object
-    logical(LGP), intent(in), optional :: reset_mover !< boolean for resetting mover
     !
     ! -- bnd has no cf routine
     !
diff --git a/src/Model/ModelUtilities/BoundaryPackageExt.f90 b/src/Model/ModelUtilities/BoundaryPackageExt.f90
new file mode 100644
index 00000000000..16d6e7e3975
--- /dev/null
+++ b/src/Model/ModelUtilities/BoundaryPackageExt.f90
@@ -0,0 +1,779 @@
+!> @brief This module contains the extended boundary package
+!!
+!! This module contains the extended boundary type that itself
+!! should be extended by model boundary packages that have been
+!! updated to source static and dynamic input data from the
+!! input context.
+!!
+!<
+module BndExtModule
+
+  use KindModule, only: DP, LGP, I4B
+  use ConstantsModule, only: LENMEMPATH, LENBOUNDNAME, LENAUXNAME, LINELENGTH
+  use ObsModule, only: obs_cr
+  use SimVariablesModule, only: errmsg
+  use SimModule, only: store_error, count_errors, store_error_filename
+  use BndModule, only: BndType
+  use GeomUtilModule, only: get_node, get_ijk
+
+  implicit none
+
+  private
+  public :: BndExtType
+
+  !> @ brief BndExtType
+  !!
+  !!  Generic extended boundary package type.  This derived type can be
+  !!  overriden to define concrete boundary package types that source
+  !!  all input from the input context.
+  !<
+  type, extends(BndType) :: BndExtType
+    ! -- characters
+    ! -- scalars
+    integer(I4B), pointer :: iper
+    ! -- arrays
+    integer(I4B), dimension(:, :), pointer, contiguous :: cellid => null()
+  contains
+    procedure :: bnd_df => bndext_df
+    procedure :: bnd_rp => bndext_rp
+    procedure :: bnd_da => bndext_da
+    procedure :: allocate_scalars => bndext_allocate_scalars
+    procedure :: allocate_arrays => bndext_allocate_arrays
+    procedure :: source_options
+    procedure :: source_dimensions
+    procedure :: log_options
+    procedure :: nodelist_update
+    procedure :: check_cellid
+    procedure :: write_list
+    procedure :: bound_value
+  end type BndExtType
+
+  !> @ brief BndExtFoundType
+  !!
+  !!  This type is used to simplify the tracking of common parameters
+  !!  that are sourced from the input context.
+  !<
+  type BndExtFoundType
+    logical :: naux = .false.
+    logical :: ipakcb = .false.
+    logical :: iprpak = .false.
+    logical :: iprflow = .false.
+    logical :: boundnames = .false.
+    logical :: auxmultname = .false.
+    logical :: inewton = .false.
+    logical :: auxiliary = .false.
+    logical :: maxbound = .false.
+  end type BndExtFoundType
+
+contains
+
+  !> @ brief Define boundary package options and dimensions
+    !!
+    !!  Define base boundary package options and dimensions for
+    !!  a model boundary package.
+    !!
+  !<
+  subroutine bndext_df(this, neq, dis)
+    ! -- modules
+    use BaseDisModule, only: DisBaseType
+    use TimeArraySeriesManagerModule, only: TimeArraySeriesManagerType, &
+                                            tasmanager_cr
+    use TimeSeriesManagerModule, only: TimeSeriesManagerType, tsmanager_cr
+    ! -- dummy variables
+    class(BndExtType), intent(inout) :: this !< BndExtType object
+    integer(I4B), intent(inout) :: neq !< number of equations
+    class(DisBaseType), pointer :: dis !< discretization object
+    !
+    ! -- set pointer to dis object for the model
+    this%dis => dis
+    !
+    ! -- Create time series managers
+    ! -- Not in use by this type but BndType uses and deallocates
+    call tsmanager_cr(this%TsManager, this%iout)
+    call tasmanager_cr(this%TasManager, dis, this%name_model, this%iout)
+    !
+    ! -- create obs package
+    call obs_cr(this%obs, this%inobspkg)
+    !
+    ! -- Write information to model list file
+    write (this%iout, 1) this%filtyp, trim(adjustl(this%text)), this%input_mempath
+1   format(1X, /1X, a, ' -- ', a, ' PACKAGE, VERSION 8, 2/22/2014', &
+           ' INPUT READ FROM MEMPATH: ', a)
+    !
+    ! -- source options
+    call this%source_options()
+    !
+    ! -- Define time series managers
+    call this%tsmanager%tsmanager_df()
+    call this%tasmanager%tasmanager_df()
+    !
+    ! -- source dimensions
+    call this%source_dimensions()
+    !
+    ! -- update package moffset for packages that add rows
+    if (this%npakeq > 0) then
+      this%ioffset = neq - this%dis%nodes
+    end if
+    !
+    ! -- update neq
+    neq = neq + this%npakeq
+    !
+    ! -- Store information needed for observations
+    if (this%bnd_obs_supported()) then
+      call this%obs%obs_df(this%iout, this%packName, this%filtyp, this%dis)
+      call this%bnd_df_obs()
+    end if
+    !
+    ! -- return
+    return
+  end subroutine bndext_df
+
+  subroutine bndext_rp(this)
+    ! -- modules
+    use TdisModule, only: kper
+    use MemoryManagerModule, only: mem_deallocate, mem_reallocate
+    use MemoryManagerExtModule, only: mem_set_value
+    ! -- dummy variables
+    class(BndExtType), intent(inout) :: this !< BndExtType object
+    ! -- local variables
+    logical(LGP) :: found
+    integer(I4B) :: n
+    !
+    if (this%iper /= kper) return
+    !
+    ! -- copy nbound from input context
+    call mem_set_value(this%nbound, 'NBOUND', this%input_mempath, &
+                       found)
+    !
+    ! -- convert cellids to node numbers
+    call this%nodelist_update()
+    !
+    ! -- update boundname string list
+    if (this%inamedbound /= 0) then
+      do n = 1, size(this%boundname_cst)
+        this%boundname(n) = this%boundname_cst(n)
+      end do
+    end if
+    !
+    ! -- return
+    return
+  end subroutine bndext_rp
+
+  !> @ brief Deallocate package memory
+  !<
+  subroutine bndext_da(this)
+    ! -- modules
+    use MemoryManagerModule, only: mem_deallocate, mem_setptr
+    ! -- dummy variables
+    class(BndExtType) :: this !< BndExtType object
+    !
+    ! -- deallocate checkin paths
+    call mem_deallocate(this%cellid, 'CELLID', this%memoryPath)
+    call mem_deallocate(this%boundname_cst, 'BOUNDNAME_IDM', this%memoryPath)
+    call mem_deallocate(this%auxvar, 'AUXVAR_IDM', this%memoryPath)
+    !
+    ! -- reassign pointers for base class _da
+    call mem_setptr(this%boundname_cst, 'BOUNDNAME_CST', this%memoryPath)
+    call mem_setptr(this%auxvar, 'AUXVAR', this%memoryPath)
+    !
+    ! -- scalars
+    nullify (this%iper)
+    !
+    ! -- deallocate
+    call this%BndType%bnd_da()
+    !
+    ! -- return
+    return
+  end subroutine bndext_da
+
+  !> @ brief Allocate package scalars
+    !!
+    !!  Allocate and initialize base boundary package scalars. This method
+    !!  only needs to be overridden if additional scalars are defined
+    !!  for a specific package.
+    !!
+  !<
+  subroutine bndext_allocate_scalars(this)
+    ! -- modules
+    use MemoryManagerModule, only: mem_setptr
+    use MemoryManagerExtModule, only: mem_set_value
+    use MemoryHelperModule, only: create_mem_path
+    use SimVariablesModule, only: idm_context
+    ! -- dummy variables
+    class(BndExtType) :: this !< BndExtType object
+    ! -- local variables
+    character(len=LENMEMPATH) :: input_mempath
+    !
+    ! -- set memory path
+    input_mempath = create_mem_path(this%name_model, this%packName, idm_context)
+    !
+    ! -- allocate base BndType scalars
+    call this%BndType%allocate_scalars()
+    !
+    ! -- set pointers to period input data scalars
+    call mem_setptr(this%iper, 'IPER', input_mempath)
+    !
+    ! -- return
+    return
+  end subroutine bndext_allocate_scalars
+
+  !> @ brief Allocate package arrays
+    !!
+    !!  Allocate and initialize base boundary package arrays. This method
+    !!  only needs to be overridden if additional arrays are defined
+    !!  for a specific package.
+    !!
+  !<
+  subroutine bndext_allocate_arrays(this, nodelist, auxvar)
+    ! -- modules
+    use MemoryManagerModule, only: mem_deallocate, mem_setptr, mem_checkin
+    ! -- dummy variables
+    class(BndExtType) :: this !< BndExtType object
+    ! -- local variables
+    integer(I4B), dimension(:), pointer, contiguous, optional :: nodelist !< package nodelist
+    real(DP), dimension(:, :), pointer, contiguous, optional :: auxvar !< package aux variable array
+    !
+    ! -- allocate base BndType arrays
+    call this%BndType%allocate_arrays(nodelist, auxvar)
+    !
+    ! -- set input context pointers
+    call mem_setptr(this%cellid, 'CELLID', this%input_mempath)
+    call mem_setptr(this%boundname_cst, 'BOUNDNAME', this%input_mempath)
+    !
+    ! -- checkin input context pointers
+    call mem_checkin(this%cellid, 'CELLID', this%memoryPath, &
+                     'CELLID', this%input_mempath)
+    call mem_checkin(this%boundname_cst, LENBOUNDNAME, 'BOUNDNAME_IDM', &
+                     this%memoryPath, 'BOUNDNAME', this%input_mempath)
+    !
+    if (present(auxvar)) then
+      ! no-op
+    else
+      ! -- set auxvar input context pointer
+      call mem_setptr(this%auxvar, 'AUXVAR', this%input_mempath)
+      !
+      ! -- checkin auxvar input context pointer
+      call mem_checkin(this%auxvar, 'AUXVAR_IDM', this%memoryPath, &
+                       'AUXVAR', this%input_mempath)
+    end if
+    !
+    ! -- return
+    return
+  end subroutine bndext_allocate_arrays
+
+  !> @ brief Source package options from input context
+  !<
+  subroutine source_options(this)
+    ! -- modules
+    use MemoryManagerModule, only: mem_reallocate, mem_setptr !, get_isize
+    use MemoryManagerExtModule, only: mem_set_value
+    use InputOutputModule, only: GetUnit, openfile
+    use CharacterStringModule, only: CharacterStringType
+    use SourceCommonModule, only: filein_fname
+    ! -- dummy variables
+    class(BndExtType), intent(inout) :: this !< BndExtType object
+    ! -- local variables
+    type(BndExtFoundType) :: found
+    character(len=LENAUXNAME) :: sfacauxname
+    integer(I4B) :: n
+    !
+    ! -- update defaults with idm sourced values
+    call mem_set_value(this%naux, 'NAUX', this%input_mempath, found%naux)
+    call mem_set_value(this%ipakcb, 'IPAKCB', this%input_mempath, found%ipakcb)
+    call mem_set_value(this%iprpak, 'IPRPAK', this%input_mempath, found%iprpak)
+    call mem_set_value(this%iprflow, 'IPRFLOW', this%input_mempath, found%iprflow)
+    call mem_set_value(this%inamedbound, 'BOUNDNAMES', this%input_mempath, &
+                       found%boundnames)
+    call mem_set_value(sfacauxname, 'AUXMULTNAME', this%input_mempath, &
+                       found%auxmultname)
+    call mem_set_value(this%inewton, 'INEWTON', this%input_mempath, found%inewton)
+    !
+    ! -- log found options
+    call this%log_options(found, sfacauxname)
+    !
+    ! -- reallocate aux arrays if aux variables provided
+    if (found%naux .and. this%naux > 0) then
+      call mem_reallocate(this%auxname, LENAUXNAME, this%naux, &
+                          'AUXNAME', this%memoryPath)
+      call mem_reallocate(this%auxname_cst, LENAUXNAME, this%naux, &
+                          'AUXNAME_CST', this%memoryPath)
+      call mem_set_value(this%auxname_cst, 'AUXILIARY', this%input_mempath, &
+                         found%auxiliary)
+      !
+      do n = 1, this%naux
+        this%auxname(n) = this%auxname_cst(n)
+      end do
+    end if
+    !
+    ! -- save flows option active
+    if (found%ipakcb) this%ipakcb = -1
+    !
+    ! -- auxmultname provided
+    if (found%auxmultname) this%iauxmultcol = -1
+    !
+    !
+    ! -- enforce 0 or 1 OBS6_FILENAME entries in option block
+    if (filein_fname(this%obs%inputFilename, 'OBS6_FILENAME', &
+                     this%input_mempath, this%input_fname)) then
+      this%obs%active = .true.
+      this%obs%inUnitObs = GetUnit()
+      call openfile(this%obs%inUnitObs, this%iout, this%obs%inputFilename, 'OBS')
+    end if
+    !
+    ! -- no newton specified
+    if (found%inewton) this%inewton = 0
+    !
+    ! -- AUXMULTNAME was specified, so find column of auxvar that will be multiplier
+    if (this%iauxmultcol < 0) then
+      !
+      ! -- Error if no aux variable specified
+      if (this%naux == 0) then
+        write (errmsg, '(a,2(1x,a))') &
+          'AUXMULTNAME was specified as', trim(adjustl(sfacauxname)), &
+          'but no AUX variables specified.'
+        call store_error(errmsg)
+      end if
+      !
+      ! -- Assign mult column
+      this%iauxmultcol = 0
+      do n = 1, this%naux
+        if (sfacauxname == this%auxname(n)) then
+          this%iauxmultcol = n
+          exit
+        end if
+      end do
+      !
+      ! -- Error if aux variable cannot be found
+      if (this%iauxmultcol == 0) then
+        write (errmsg, '(a,2(1x,a))') &
+          'AUXMULTNAME was specified as', trim(adjustl(sfacauxname)), &
+          'but no AUX variable found with this name.'
+        call store_error(errmsg)
+      end if
+    end if
+    !
+    ! -- terminate if errors were detected
+    if (count_errors() > 0) then
+      call store_error_filename(this%input_fname)
+    end if
+    !
+    ! -- return
+    return
+  end subroutine source_options
+
+  !> @ brief Log package options
+  !<
+  subroutine log_options(this, found, sfacauxname)
+    ! -- modules
+    ! -- dummy variables
+    class(BndExtType), intent(inout) :: this !< BndExtType object
+    type(BndExtFoundType), intent(in) :: found
+    character(len=*), intent(in) :: sfacauxname
+    ! -- local variables
+    ! -- format
+    character(len=*), parameter :: fmtflow = &
+      &"(4x, 'FLOWS WILL BE SAVED TO BUDGET FILE SPECIFIED IN OUTPUT CONTROL')"
+    character(len=*), parameter :: fmttas = &
+      &"(4x, 'TIME-ARRAY SERIES DATA WILL BE READ FROM FILE: ', a)"
+    character(len=*), parameter :: fmtts = &
+      &"(4x, 'TIME-SERIES DATA WILL BE READ FROM FILE: ', a)"
+    character(len=*), parameter :: fmtnme = &
+      &"(a, i0, a)"
+    !
+    ! -- log found options
+    write (this%iout, '(/1x,a)') 'PROCESSING '//trim(adjustl(this%text)) &
+      //' BASE OPTIONS'
+    !
+    if (found%ipakcb) then
+      write (this%iout, fmtflow)
+    end if
+    !
+    if (found%iprpak) then
+      write (this%iout, '(4x,a)') &
+        'LISTS OF '//trim(adjustl(this%text))//' CELLS WILL BE PRINTED.'
+    end if
+    !
+    if (found%iprflow) then
+      write (this%iout, '(4x,a)') trim(adjustl(this%text))// &
+        ' FLOWS WILL BE PRINTED TO LISTING FILE.'
+    end if
+    !
+    if (found%boundnames) then
+      write (this%iout, '(4x,a)') trim(adjustl(this%text))// &
+        ' BOUNDARIES HAVE NAMES IN LAST COLUMN.'
+    end if
+    !
+    if (found%auxmultname) then
+      write (this%iout, '(4x,a,a)') &
+        'AUXILIARY MULTIPLIER NAME: ', sfacauxname
+    end if
+    !
+    if (found%inewton) then
+      write (this%iout, '(4x,a)') &
+        'NEWTON-RAPHSON method disabled for unconfined cells'
+    end if
+    !
+    ! -- close logging block
+    write (this%iout, '(1x,a)') &
+      'END OF '//trim(adjustl(this%text))//' BASE OPTIONS'
+    !
+    ! -- return
+    return
+  end subroutine log_options
+
+  !> @ brief Source package dimensions from input context
+  !<
+  subroutine source_dimensions(this)
+    use MemoryManagerExtModule, only: mem_set_value
+    ! -- dummy variables
+    class(BndExtType), intent(inout) :: this !< BndExtType object
+    ! -- local variables
+    type(BndExtFoundType) :: found
+    !
+    ! -- open dimensions logging block
+    write (this%iout, '(/1x,a)') 'PROCESSING '//trim(adjustl(this%text))// &
+      ' BASE DIMENSIONS'
+    !
+    ! -- update defaults with idm sourced values
+    call mem_set_value(this%maxbound, 'MAXBOUND', this%input_mempath, &
+                       found%maxbound)
+    !
+    write (this%iout, '(4x,a,i7)') 'MAXBOUND = ', this%maxbound
+    !
+    ! -- close logging block
+    write (this%iout, '(1x,a)') &
+      'END OF '//trim(adjustl(this%text))//' BASE DIMENSIONS'
+    !
+    ! -- verify dimensions were set
+    if (this%maxbound <= 0) then
+      write (errmsg, '(a)') 'MAXBOUND must be an integer greater than zero.'
+      call store_error(errmsg)
+      call store_error_filename(this%input_fname)
+    end if
+    !
+    ! -- Call define_listlabel to construct the list label that is written
+    !    when PRINT_INPUT option is used.
+    call this%define_listlabel()
+    !
+    ! -- return
+    return
+  end subroutine source_dimensions
+
+  !> @ brief Update package nodelist
+    !!
+    !! Convert period updated cellids to node numbers.
+    !!
+  !<
+  subroutine nodelist_update(this)
+    ! -- modules
+    use SimVariablesModule, only: errmsg
+    ! -- dummy
+    class(BndExtType) :: this !< BndExtType object
+    ! -- local
+    integer(I4B), dimension(:), pointer :: cellid
+    integer(I4B) :: n, nodeu, noder
+    character(len=LINELENGTH) :: nodestr
+    !
+    ! -- update nodelist
+    do n = 1, this%nbound
+      !
+      ! -- set cellid
+      cellid => this%cellid(:, n)
+      !
+      ! -- ensure cellid is valid, store an error otherwise
+      call this%check_cellid(n, cellid, this%dis%mshape, this%dis%ndim)
+      !
+      ! -- Determine user node number
+      if (this%dis%ndim == 1) then
+        nodeu = cellid(1)
+      elseif (this%dis%ndim == 2) then
+        nodeu = get_node(cellid(1), 1, cellid(2), &
+                         this%dis%mshape(1), 1, &
+                         this%dis%mshape(2))
+      else
+        nodeu = get_node(cellid(1), cellid(2), cellid(3), &
+                         this%dis%mshape(1), &
+                         this%dis%mshape(2), &
+                         this%dis%mshape(3))
+      end if
+      !
+      ! -- update the nodelist
+      if (this%dis%nodes < this%dis%nodesuser) then
+        ! -- convert user to reduced node numbers
+        noder = this%dis%get_nodenumber(nodeu, 0)
+        if (noder <= 0) then
+          call this%dis%nodeu_to_string(nodeu, nodestr)
+          write (errmsg, *) &
+            ' Cell is outside active grid domain: '// &
+            trim(adjustl(nodestr))
+          call store_error(errmsg)
+        end if
+        this%nodelist(n) = noder
+      else
+        this%nodelist(n) = nodeu
+      end if
+    end do
+    !
+    ! -- exit if errors were found
+    if (count_errors() > 0) then
+      write (errmsg, *) count_errors(), ' errors encountered.'
+      call store_error(errmsg)
+      call store_error_filename(this%input_fname)
+    end if
+    !
+    ! -- return
+    return
+  end subroutine nodelist_update
+
+  !> @ brief Check for valid cellid
+  !<
+  subroutine check_cellid(this, ii, cellid, mshape, ndim)
+    ! -- modules
+    use SimVariablesModule, only: errmsg
+    ! -- dummy
+    class(BndExtType) :: this !< BndExtType object
+    ! -- local
+    integer(I4B), intent(in) :: ii
+    integer(I4B), dimension(:), intent(in) :: cellid !< cellid
+    integer(I4B), dimension(:), intent(in) :: mshape !< model shape
+    integer(I4B), intent(in) :: ndim !< size of mshape
+    character(len=20) :: cellstr, mshstr
+    character(len=*), parameter :: fmterr = &
+      "('List entry ',i0,' contains cellid ',a,' but this cellid is invalid &
+      &for model with shape ', a)"
+    character(len=*), parameter :: fmtndim1 = &
+                                   "('(',i0,')')"
+    character(len=*), parameter :: fmtndim2 = &
+                                   "('(',i0,',',i0,')')"
+    character(len=*), parameter :: fmtndim3 = &
+                                   "('(',i0,',',i0,',',i0,')')"
+    select case (ndim)
+    case (1)
+      !
+      if (cellid(1) < 1 .or. cellid(1) > mshape(1)) then
+        write (cellstr, fmtndim1) cellid(1)
+        write (mshstr, fmtndim1) mshape(1)
+        write (errmsg, fmterr) ii, trim(adjustl(cellstr)), trim(adjustl(mshstr))
+        call store_error(errmsg)
+      end if
+      !
+    case (2)
+      !
+      if (cellid(1) < 1 .or. cellid(1) > mshape(1) .or. &
+          cellid(2) < 1 .or. cellid(2) > mshape(2)) then
+        write (cellstr, fmtndim2) cellid(1), cellid(2)
+        write (mshstr, fmtndim2) mshape(1), mshape(2)
+        write (errmsg, fmterr) ii, trim(adjustl(cellstr)), trim(adjustl(mshstr))
+        call store_error(errmsg)
+      end if
+      !
+    case (3)
+      !
+      if (cellid(1) < 1 .or. cellid(1) > mshape(1) .or. &
+          cellid(2) < 1 .or. cellid(2) > mshape(2) .or. &
+          cellid(3) < 1 .or. cellid(3) > mshape(3)) then
+        write (cellstr, fmtndim3) cellid(1), cellid(2), cellid(3)
+        write (mshstr, fmtndim3) mshape(1), mshape(2), mshape(3)
+        write (errmsg, fmterr) ii, trim(adjustl(cellstr)), trim(adjustl(mshstr))
+        call store_error(errmsg)
+      end if
+      !
+    case default
+    end select
+    !
+    ! -- return
+    return
+  end subroutine check_cellid
+
+  !> @ brief Log package list input
+    !!
+    !! Log period list based input. This routine requires a package specific
+    !! bound_value() routine to report accurate bound values.
+    !!
+  !<
+  subroutine write_list(this)
+    ! -- modules
+    use ConstantsModule, only: LINELENGTH, LENBOUNDNAME, &
+                               TABLEFT, TABCENTER, DZERO
+    use InputOutputModule, only: ulstlb
+    use TableModule, only: TableType, table_cr
+    ! -- dummy
+    class(BndExtType) :: this !< BndExtType object
+    ! -- local
+    character(len=10) :: cpos
+    character(len=LINELENGTH) :: tag
+    character(len=LINELENGTH), allocatable, dimension(:) :: words
+    integer(I4B) :: ntabrows
+    integer(I4B) :: ntabcols
+    integer(I4B) :: ipos
+    integer(I4B) :: ii, jj, i, j, k, nod
+    integer(I4B) :: ldim
+    integer(I4B) :: naux
+    type(TableType), pointer :: inputtab => null()
+    ! -- formats
+    character(len=LINELENGTH) :: fmtlstbn
+! ------------------------------------------------------------------------------
+    !
+    ! -- Determine sizes
+    ldim = this%ncolbnd
+    naux = size(this%auxvar, 1)
+    !
+    ! -- dimension table
+    ntabrows = this%nbound
+    !
+    ! -- start building format statement to parse this%label, which
+    !    contains the column headers (except for boundname and auxnames)
+    ipos = index(this%listlabel, 'NO.')
+    if (ipos /= 0) then
+      write (cpos, '(i10)') ipos + 3
+      fmtlstbn = '(a'//trim(adjustl(cpos))
+    else
+      fmtlstbn = '(a7'
+    end if
+    ! -- sequence number, layer, row, and column.
+    if (size(this%dis%mshape) == 3) then
+      ntabcols = 4
+      fmtlstbn = trim(fmtlstbn)//',a7,a7,a7'
+      !
+      ! -- sequence number, layer, and cell2d.
+    else if (size(this%dis%mshape) == 2) then
+      ntabcols = 3
+      fmtlstbn = trim(fmtlstbn)//',a7,a7'
+      !
+      ! -- sequence number and node.
+    else
+      ntabcols = 2
+      fmtlstbn = trim(fmtlstbn)//',a7'
+    end if
+    !
+    ! -- Add fields for non-optional real values
+    ntabcols = ntabcols + ldim
+    do i = 1, ldim
+      fmtlstbn = trim(fmtlstbn)//',a16'
+    end do
+    !
+    ! -- Add field for boundary name
+    if (this%inamedbound == 1) then
+      ntabcols = ntabcols + 1
+      fmtlstbn = trim(fmtlstbn)//',a16'
+    end if
+    !
+    ! -- Add fields for auxiliary variables
+    ntabcols = ntabcols + naux
+    do i = 1, naux
+      fmtlstbn = trim(fmtlstbn)//',a16'
+    end do
+    fmtlstbn = trim(fmtlstbn)//')'
+    !
+    ! -- allocate words
+    allocate (words(ntabcols))
+    !
+    ! -- parse this%listlabel into words
+    read (this%listlabel, fmtlstbn) (words(i), i=1, ntabcols)
+    !
+    ! -- initialize the input table object
+    call table_cr(inputtab, ' ', ' ')
+    call inputtab%table_df(ntabrows, ntabcols, this%iout)
+    !
+    ! -- add the columns
+    ipos = 1
+    call inputtab%initialize_column(words(ipos), 10, alignment=TABCENTER)
+    !
+    ! -- discretization
+    do i = 1, size(this%dis%mshape)
+      ipos = ipos + 1
+      call inputtab%initialize_column(words(ipos), 7, alignment=TABCENTER)
+    end do
+    !
+    ! -- non-optional variables
+    do i = 1, ldim
+      ipos = ipos + 1
+      call inputtab%initialize_column(words(ipos), 16, alignment=TABCENTER)
+    end do
+    !
+    ! -- boundname
+    if (this%inamedbound == 1) then
+      ipos = ipos + 1
+      tag = 'BOUNDNAME'
+      call inputtab%initialize_column(tag, LENBOUNDNAME, alignment=TABLEFT)
+    end if
+    !
+    ! -- aux variables
+    do i = 1, naux
+      call inputtab%initialize_column(this%auxname(i), 16, alignment=TABCENTER)
+    end do
+    !
+    ! -- Write the table
+    do ii = 1, this%nbound
+      call inputtab%add_term(ii)
+      !
+      ! -- discretization
+      if (size(this%dis%mshape) == 3) then
+        nod = this%nodelist(ii)
+        call get_ijk(nod, this%dis%mshape(2), this%dis%mshape(3), &
+                     this%dis%mshape(1), i, j, k)
+        call inputtab%add_term(k)
+        call inputtab%add_term(i)
+        call inputtab%add_term(j)
+      else if (size(this%dis%mshape) == 2) then
+        nod = this%nodelist(ii)
+        call get_ijk(nod, 1, this%dis%mshape(2), this%dis%mshape(1), i, j, k)
+        call inputtab%add_term(k)
+        call inputtab%add_term(j)
+      else
+        nod = this%nodelist(ii)
+        call inputtab%add_term(nod)
+      end if
+      !
+      ! -- non-optional variables
+      do jj = 1, ldim
+        call inputtab%add_term(this%bound_value(jj, ii))
+      end do
+      !
+      ! -- boundname
+      if (this%inamedbound == 1) then
+        call inputtab%add_term(this%boundname(ii))
+      end if
+      !
+      ! -- aux variables
+      do jj = 1, naux
+        call inputtab%add_term(this%auxvar(jj, ii))
+      end do
+    end do
+    !
+    ! -- deallocate the local variables
+    call inputtab%table_da()
+    deallocate (inputtab)
+    nullify (inputtab)
+    deallocate (words)
+    !
+    ! -- return
+    return
+  end subroutine write_list
+
+  !> @ brief Return a bound value
+    !!
+    !!  Return a bound value associated with an ncolbnd index
+    !!  and row.  This function should be overridden in the
+    !!  derived package class.
+    !!
+  !<
+  function bound_value(this, col, row) result(bndval)
+    ! -- modules
+    use ConstantsModule, only: DNODATA
+    ! -- dummy variables
+    class(BndExtType), intent(inout) :: this !< BndExtType object
+    integer(I4B), intent(in) :: col
+    integer(I4B), intent(in) :: row
+    ! -- result
+    real(DP) :: bndval
+    !
+    ! -- override this return value by redefining this
+    !    routine in the derived package.
+    bndval = DNODATA
+    !
+    ! -- return
+    return
+  end function bound_value
+
+end module BndExtModule
diff --git a/src/Model/ModelUtilities/Connections.f90 b/src/Model/ModelUtilities/Connections.f90
index 9dfaec39fae..2092b3a6e53 100644
--- a/src/Model/ModelUtilities/Connections.f90
+++ b/src/Model/ModelUtilities/Connections.f90
@@ -3,9 +3,10 @@ module ConnectionsModule
   use ArrayReadersModule, only: ReadArray
   use KindModule, only: DP, I4B
   use ConstantsModule, only: LENMODELNAME, LENMEMPATH
-  use GenericUtilitiesModule, only: sim_message
+  use MessageModule, only: write_message
   use SimVariablesModule, only: errmsg
   use BlockParserModule, only: BlockParserType
+  use GeomUtilModule, only: get_node
 
   implicit none
   private
@@ -35,7 +36,9 @@ module ConnectionsModule
     integer(I4B), dimension(:), pointer, contiguous :: iausr => null() !< (size:nodesusr+1)
     integer(I4B), dimension(:), pointer, contiguous :: jausr => null() !< (size:nja)
     type(BlockParserType) :: parser !< block parser
+
   contains
+
     procedure :: con_da
     procedure :: allocate_scalars
     procedure :: allocate_arrays
@@ -52,18 +55,13 @@ module ConnectionsModule
 
 contains
 
+  !> @brief Deallocate connection variables
+  !<
   subroutine con_da(this)
-! ******************************************************************************
-! con_da -- Deallocate connection variables
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(ConnectionsType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Strings
     deallocate (this%name_model)
@@ -103,28 +101,23 @@ subroutine con_da(this)
     call mem_deallocate(this%cl1)
     call mem_deallocate(this%cl2)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine con_da
 
+  !> @brief Allocate scalars for ConnectionsType
+  !<
   subroutine allocate_scalars(this, name_model)
-! ******************************************************************************
-! allocate_scalars -- Allocate scalars for ConnectionsType
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     use MemoryHelperModule, only: create_mem_path
     ! -- dummy
     class(ConnectionsType) :: this
     character(len=*), intent(in) :: name_model
-! ------------------------------------------------------------------------------
     !
     ! -- allocate
     allocate (this%name_model)
-
+    !
     this%memoryPath = create_mem_path(name_model, 'CON')
     call mem_allocate(this%nodes, 'NODES', this%memoryPath)
     call mem_allocate(this%nja, 'NJA', this%memoryPath)
@@ -140,17 +133,12 @@ subroutine allocate_scalars(this, name_model)
     return
   end subroutine allocate_scalars
 
+  !> @brief Allocate arrays for ConnectionsType
+  !<
   subroutine allocate_arrays(this)
-! ******************************************************************************
-! allocate_arrays -- Allocate arrays for ConnectionsType
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(ConnectionsType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- allocate space for connection arrays
     call mem_allocate(this%ia, this%nodes + 1, 'IA', this%memoryPath)
@@ -173,13 +161,9 @@ subroutine allocate_arrays(this)
     return
   end subroutine allocate_arrays
 
+  !> @brief Finalize connection data
+  !<
   subroutine con_finalize(this, ihctemp, cl12temp, hwvatemp, angldegx)
-! ******************************************************************************
-! con_finalize -- Finalize connection data
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH, DONE, DHALF, DPIO180, DNODATA
     use SimModule, only: store_error, count_errors, store_error_unit
@@ -220,7 +204,6 @@ subroutine con_finalize(this, ihctemp, cl12temp, hwvatemp, angldegx)
     data aname(4)/'                    CL12'/
     data aname(5)/'                    HWVA'/
     data aname(6)/'                ANGLDEGX'/
-! ------------------------------------------------------------------------------
     !
     ! -- Convert any negative ja numbers to positive
     do ii = 1, this%nja
@@ -341,14 +324,10 @@ subroutine con_finalize(this, ihctemp, cl12temp, hwvatemp, angldegx)
     return
   end subroutine con_finalize
 
+  !> @brief Read and process IAC and JA from an an input block called
+  !! CONNECTIONDATA
+  !<
   subroutine read_connectivity_from_block(this, name_model, nodes, nja, iout)
-! ******************************************************************************
-! read_connectivity_from_block -- Read and process IAC and JA from an
-! an input block called CONNECTIONDATA
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error, count_errors
@@ -377,7 +356,6 @@ subroutine read_connectivity_from_block(this, name_model, nodes, nja, iout)
     ! -- data
     data aname(1)/'                     IAC'/
     data aname(2)/'                      JA'/
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate and initialize dimensions
     call this%allocate_scalars(name_model)
@@ -456,7 +434,7 @@ subroutine read_connectivity_from_block(this, name_model, nodes, nja, iout)
         m = this%ja(ii)
         if (n /= this%ja(this%isym(ii))) then
           write (line, fmtsymerr) aname(2), ii, this%isym(ii)
-          call sim_message(line)
+          call write_message(line)
           call this%parser%StoreErrorUnit()
         end if
       end do
@@ -470,14 +448,9 @@ subroutine read_connectivity_from_block(this, name_model, nodes, nja, iout)
     return
   end subroutine read_connectivity_from_block
 
+  !> @brief Using a vector of cell lengths, calculate the cl1 and cl2 arrays.
+  !<
   subroutine set_cl1_cl2_from_fleng(this, fleng)
-! ******************************************************************************
-! set_cl1_cl2_from_fleng -- Using a vector of cell lengths,
-! calculate the cl1 and cl2 arrays.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DHALF
     ! -- dummy
@@ -485,7 +458,6 @@ subroutine set_cl1_cl2_from_fleng(this, fleng)
     real(DP), dimension(:), intent(in) :: fleng
     ! -- local
     integer(I4B) :: n, m, ii
-! ------------------------------------------------------------------------------
     !
     ! -- Fill symmetric arrays cl1 and cl2 from fleng of the node
     do n = 1, this%nodes
@@ -500,20 +472,15 @@ subroutine set_cl1_cl2_from_fleng(this, fleng)
     return
   end subroutine set_cl1_cl2_from_fleng
 
+  !> @brief Construct the connectivity arrays for a structured
+  !! three-dimensional grid.
+  !<
   subroutine disconnections(this, name_model, nodes, ncol, nrow, nlay, &
                             nrsize, delr, delc, top, bot, nodereduced, &
                             nodeuser)
-! ******************************************************************************
-! disconnections -- Construct the connectivity arrays for a structured
-!   three-dimensional grid.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DHALF, DZERO, DTHREE, DTWO, DPI
     use SparseModule, only: sparsematrix
-    use InputOutputModule, only: get_node
     ! -- dummy
     class(ConnectionsType) :: this
     character(len=*), intent(in) :: name_model
@@ -534,7 +501,6 @@ subroutine disconnections(this, name_model, nodes, ncol, nrow, nlay, &
     type(sparsematrix) :: sparse
     integer(I4B) :: i, j, k, kk, ierror, isympos, nodesuser
     integer(I4B) :: nr, mr
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate scalars
     call this%allocate_scalars(name_model)
@@ -749,20 +715,14 @@ subroutine disconnections(this, name_model, nodes, ncol, nrow, nlay, &
     return
   end subroutine disconnections
 
+  !> @brief Construct the connectivity arrays using cell disv information
+  !<
   subroutine disvconnections(this, name_model, nodes, ncpl, nlay, nrsize, &
                              nvert, vertex, iavert, javert, cellxy, &
                              top, bot, nodereduced, nodeuser)
-! ******************************************************************************
-! disvconnections -- Construct the connectivity arrays using cell disv
-!   information.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DHALF, DZERO, DTHREE, DTWO, DPI
     use SparseModule, only: sparsematrix
-    use InputOutputModule, only: get_node
     use DisvGeom, only: DisvGeomType
     use MemoryManagerModule, only: mem_reallocate
     ! -- dummy
@@ -786,7 +746,6 @@ subroutine disvconnections(this, name_model, nodes, ncpl, nlay, nrsize, &
     type(sparsematrix) :: sparse, vertcellspm
     integer(I4B) :: n, m, ipos, i, j, ierror, nodesuser
     type(DisvGeomType) :: cell1, cell2
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate scalars
     call this%allocate_scalars(name_model)
@@ -857,17 +816,13 @@ subroutine disvconnections(this, name_model, nodes, ncpl, nlay, nrsize, &
     return
   end subroutine disvconnections
 
+  !> @brief Construct the connectivity arrays using disu information.  Grid
+  !! may be reduced
+  !<
   subroutine disuconnections(this, name_model, nodes, nodesuser, nrsize, &
                              nodereduced, nodeuser, iainp, jainp, &
                              ihcinp, cl12inp, hwvainp, angldegxinp, &
                              iangledegx)
-! ******************************************************************************
-! disuconnections -- Construct the connectivity arrays using disu
-!   information.  Grid may be reduced
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DHALF, DZERO, DTHREE, DTWO, DPI
     use SparseModule, only: sparsematrix
@@ -895,7 +850,6 @@ subroutine disuconnections(this, name_model, nodes, nodesuser, nrsize, &
     integer(I4B) :: nr, nu, mr, mu, ipos, iposr, ierror
     integer(I4B), dimension(:), allocatable :: rowmaxnnz
     type(sparsematrix) :: sparse
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate scalars
     call this%allocate_scalars(name_model)
@@ -997,14 +951,10 @@ subroutine disuconnections(this, name_model, nodes, nodesuser, nrsize, &
     return
   end subroutine disuconnections
 
+  !> @brief Fill iausr and jausr if reduced grid, otherwise point them to ia
+  !! and ja.
+  !<
   subroutine iajausr(this, nrsize, nodesuser, nodereduced, nodeuser)
-! ******************************************************************************
-! iajausr -- Fill iausr and jausr if reduced grid, otherwise point them
-!   to ia and ja.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_reallocate, mem_deallocate, mem_setptr
     ! -- dummy
@@ -1015,7 +965,6 @@ subroutine iajausr(this, nrsize, nodesuser, nodereduced, nodeuser)
     integer(I4B), dimension(:), intent(in) :: nodeuser
     ! -- local
     integer(I4B) :: n, nr, ipos
-! ------------------------------------------------------------------------------
     !
     ! -- If reduced system, then need to build iausr and jausr, otherwise point
     !    them to ia and ja.
@@ -1054,19 +1003,17 @@ subroutine iajausr(this, nrsize, nodesuser, nodereduced, nodeuser)
     return
   end subroutine iajausr
 
+  !> @brief Get the index in the JA array corresponding to the connection
+  !! between two nodes of interest.
+  !!
+  !! Node1 is used as the index in the IA array, and IA(Node1) is the row index
+  !! in the (nodes x nodes) matrix represented by the compressed sparse row
+  !! format.
+  !!
+  !! -1 is returned if either node number is invalid.
+  !!  0 is returned if the two nodes are not connected.
+  !<
   function getjaindex(this, node1, node2)
-! ******************************************************************************
-! Get the index in the JA array corresponding to the connection between
-! two nodes of interest.  Node1 is used as the index in the IA array, and
-! IA(Node1) is the row index in the (nodes x nodes) matrix represented by
-! the compressed sparse row format.
-!
-!   -1 is returned if either node number is invalid.
-!    0 is returned if the two nodes are not connected.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     integer(I4B) :: getjaindex
     ! -- dummy
@@ -1074,7 +1021,6 @@ function getjaindex(this, node1, node2)
     integer(I4B), intent(in) :: node1, node2 ! nodes of interest
     ! -- local
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     ! -- error checking
     if (node1 < 1 .or. node1 > this%nodes .or. node2 < 1 .or. &
@@ -1103,13 +1049,9 @@ function getjaindex(this, node1, node2)
     return
   end function getjaindex
 
+  !> @brief Function to fill the isym array
+  !<
   subroutine fillisym(neq, nja, ia, ja, isym)
-! ******************************************************************************
-! fillisym -- function to fill the isym array
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     integer(I4B), intent(in) :: neq
     integer(I4B), intent(in) :: nja
@@ -1118,7 +1060,6 @@ subroutine fillisym(neq, nja, ia, ja, isym)
     integer(I4B), intent(in), dimension(neq + 1) :: ia
     integer(I4B), intent(in), dimension(nja) :: ja
     integer(I4B) :: n, m, ii, jj
-! ------------------------------------------------------------------------------
     !
     do n = 1, neq
       do ii = ia(n), ia(n + 1) - 1
@@ -1141,13 +1082,9 @@ subroutine fillisym(neq, nja, ia, ja, isym)
     return
   end subroutine fillisym
 
+  !> @brief Function to fill the jas array
+  !<
   subroutine filljas(neq, nja, ia, ja, isym, jas)
-! ******************************************************************************
-! fillisym -- function to fill the jas array
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     integer(I4B), intent(in) :: neq
     integer(I4B), intent(in) :: nja
@@ -1157,7 +1094,6 @@ subroutine filljas(neq, nja, ia, ja, isym, jas)
     integer(I4B), intent(inout), dimension(nja) :: jas
     ! -- local
     integer(I4B) :: n, m, ii, ipos
-! ------------------------------------------------------------------------------
     !
     ! -- set diagonal to zero and fill upper
     ipos = 1
@@ -1186,17 +1122,12 @@ subroutine filljas(neq, nja, ia, ja, isym, jas)
     return
   end subroutine filljas
 
+  !> @brief Routine to make cell connections from vertices
+  !<
   subroutine vertexconnect(nodes, nrsize, maxnnz, nlay, ncpl, sparse, &
                            vertcellspm, cell1, cell2, nodereduced)
-! ******************************************************************************
-! vertexconnect -- routine to make cell connections from vertices
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SparseModule, only: sparsematrix
-    use InputOutputModule, only: get_node
     use DisvGeom, only: DisvGeomType
     ! -- dummy
     integer(I4B), intent(in) :: nodes
@@ -1211,7 +1142,6 @@ subroutine vertexconnect(nodes, nrsize, maxnnz, nlay, ncpl, sparse, &
     ! -- local
     integer(I4B), dimension(:), allocatable :: rowmaxnnz
     integer(I4B) :: i, j, k, kk, nr, mr, j1, j2, icol1, icol2, nvert
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate and fill the ia and ja arrays
     allocate (rowmaxnnz(nodes))
@@ -1284,25 +1214,22 @@ subroutine vertexconnect(nodes, nrsize, maxnnz, nlay, ncpl, sparse, &
       end do
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine vertexconnect
 
+  !> @brief routine to set a value in the mask array (which has the same shape
+  !! as this%ja)
+  !<
   subroutine set_mask(this, ipos, maskval)
-! ******************************************************************************
-! set_mask -- routine to set a value in the mask array
-! (which has the same shape as this%ja)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use MemoryManagerModule, only: mem_allocate
+    ! -- dummy
     class(ConnectionsType) :: this
     integer(I4B), intent(in) :: ipos
     integer(I4B), intent(in) :: maskval
-    ! local
+    ! -- local
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     ! if we still point to this%ja, we first need to allocate space
     if (associated(this%mask, this%ja)) then
@@ -1316,23 +1243,18 @@ subroutine set_mask(this, ipos, maskval)
     ! -- set the mask value
     this%mask(ipos) = maskVal
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine set_mask
 
+  !> @brief Convert an iac array into an ia array
+  !<
   subroutine iac_to_ia(iac, ia)
-! ******************************************************************************
-! iac_to_ia -- convert an iac array into an ia array
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     integer(I4B), dimension(:), contiguous, pointer, intent(in) :: iac
     integer(I4B), dimension(:), contiguous, intent(inout) :: ia
     ! -- local
     integer(I4B) :: n, nodes
-! ------------------------------------------------------------------------------
     !
     ! -- Convert iac to ia
     nodes = size(iac)
@@ -1349,7 +1271,7 @@ subroutine iac_to_ia(iac, ia)
     end do
     ia(1) = 1
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine iac_to_ia
 
diff --git a/src/Model/ModelUtilities/DiscretizationBase.f90 b/src/Model/ModelUtilities/DiscretizationBase.f90
index dd03ac8faa3..927b49c6926 100644
--- a/src/Model/ModelUtilities/DiscretizationBase.f90
+++ b/src/Model/ModelUtilities/DiscretizationBase.f90
@@ -1,16 +1,17 @@
 module BaseDisModule
 
-  use KindModule, only: DP, I4B
+  use KindModule, only: DP, I4B, LGP
   use ConstantsModule, only: LENMODELNAME, LENAUXNAME, LINELENGTH, &
                              DZERO, LENMEMPATH, DPIO180
   use SmoothingModule, only: sQuadraticSaturation
   use ConnectionsModule, only: ConnectionsType
-  use InputOutputModule, only: URWORD, ubdsv1
+  use InputOutputModule, only: URWORD, ubdsv1, ubdsvd
   use SimVariablesModule, only: errmsg
   use SimModule, only: count_errors, store_error, &
                        store_error_unit
   use BlockParserModule, only: BlockParserType
   use MemoryManagerModule, only: mem_allocate
+  use MemoryManagerExtModule, only: mem_set_value
   use MemoryHelperModule, only: create_mem_path
   use TdisModule, only: kstp, kper, pertim, totim, delt
   use TimeSeriesManagerModule, only: TimeSeriesManagerType
@@ -24,8 +25,8 @@ module BaseDisModule
 
   type :: DisBaseType
     character(len=LENMEMPATH) :: memoryPath !< path for memory allocation
+    character(len=LENMEMPATH) :: input_mempath = '' !< input context mempath
     character(len=LENMODELNAME), pointer :: name_model => null() !< name of the model
-    character(len=LENMEMPATH), pointer :: input_mempath => null() !< input context mempath
     character(len=LINELENGTH), pointer :: input_fname => null() !< input file name
     integer(I4B), pointer :: inunit => null() !< unit number for input file
     integer(I4B), pointer :: iout => null() !< unit number for output file
@@ -86,6 +87,7 @@ module BaseDisModule
     procedure :: allocate_arrays
     procedure :: get_ncpl
     procedure :: get_cell_volume
+    procedure :: get_polyverts
     procedure :: write_grb
     !
     procedure :: read_int_array
@@ -107,36 +109,21 @@ module BaseDisModule
     procedure, public :: nlarray_to_nodelist
     procedure, public :: highest_active
     procedure, public :: get_area
+    procedure, public :: get_area_factor
 
   end type DisBaseType
 
 contains
 
+  !> @brief Define the discretization
   subroutine dis_df(this)
-! ******************************************************************************
-! dis_df -- Read discretization information from DISU input file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- dummy
     class(DisBaseType) :: this
-! ------------------------------------------------------------------------------
-    !
-    call store_error('Program error: DisBaseType method dis_df not &
-                     &implemented.', terminate=.TRUE.)
-    !
-    ! -- Return
-    return
+    call store_error('Programmer error: dis_df must be overridden', &
+                     terminate=.true.)
   end subroutine dis_df
 
+  !> @brief Add connections to sparse cell connectivity matrix
   subroutine dis_ac(this, moffset, sparse)
-! ******************************************************************************
-! dis_ac -- Add connections to sparse based on cell connectivity
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SparseModule, only: sparsematrix
     ! -- dummy
@@ -145,7 +132,6 @@ subroutine dis_ac(this, moffset, sparse)
     type(sparsematrix), intent(inout) :: sparse
     ! -- local
     integer(I4B) :: i, j, ipos, iglo, jglo
-! ------------------------------------------------------------------------------
     !
     do i = 1, this%nodes
       do ipos = this%con%ia(i), this%con%ia(i + 1) - 1
@@ -155,20 +141,10 @@ subroutine dis_ac(this, moffset, sparse)
         call sparse%addconnection(iglo, jglo, 1)
       end do
     end do
-    !
-    ! -- Return
-    return
   end subroutine dis_ac
 
+  !> @brief Map cell connections in the numerical solution coefficient matrix.
   subroutine dis_mc(this, moffset, idxglo, matrix_sln)
-! ******************************************************************************
-! dis_mc -- Map the positions of cell connections in the numerical solution
-!   coefficient matrix.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(DisBaseType) :: this
     integer(I4B), intent(in) :: moffset
@@ -176,7 +152,6 @@ subroutine dis_mc(this, moffset, idxglo, matrix_sln)
     class(MatrixBaseType), pointer :: matrix_sln
     ! -- local
     integer(I4B) :: i, j, ipos, iglo, jglo
-! ------------------------------------------------------------------------------
     !
     do i = 1, this%nodes
       iglo = i + moffset
@@ -186,26 +161,16 @@ subroutine dis_mc(this, moffset, idxglo, matrix_sln)
         idxglo(ipos) = matrix_sln%get_position(iglo, jglo)
       end do
     end do
-    !
-    ! -- Return
-    return
   end subroutine dis_mc
 
+  !> @brief Allocate and setup variables, and write binary grid file.
   subroutine dis_ar(this, icelltype)
-! ******************************************************************************
-! dis_ar -- Called from AR procedure.  Only task is to write binary grid file.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(DisBaseType) :: this
     integer(I4B), dimension(:), intent(in) :: icelltype
     ! -- local
     integer(I4B), dimension(:), allocatable :: ict
     integer(I4B) :: nu, nr
-! ------------------------------------------------------------------------------
     !
     ! -- Expand icelltype to full grid; fill with 0 if cell is excluded
     allocate (ict(this%nodesuser))
@@ -219,49 +184,25 @@ subroutine dis_ar(this, icelltype)
     end do
     !
     if (this%nogrb == 0) call this%write_grb(ict)
-    !
-    ! -- Return
-    return
   end subroutine dis_ar
 
+  !> @brief Write a binary grid file
   subroutine write_grb(this, icelltype)
-! ******************************************************************************
-! write_grb -- Called from AR procedure.  Only task is to write binary grid file.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    ! -- dummy
     class(DisBaseType) :: this
     integer(I4B), dimension(:), intent(in) :: icelltype
-    ! -- local
-! ------------------------------------------------------------------------------
-    !
-    !
-    call store_error('Program error: DisBaseType method write_grb not &
-                     &implemented.', terminate=.TRUE.)
-    !
-    ! -- Return
-    return
+    call store_error('Programmer error: write_grb must be overridden', &
+                     terminate=.true.)
   end subroutine write_grb
 
+  !> @brier Deallocate variables
   subroutine dis_da(this)
-! ******************************************************************************
-! dis_da -- Deallocate discretization object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(DisBaseType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Strings
     deallocate (this%name_model)
-    deallocate (this%input_mempath)
     deallocate (this%input_fname)
     !
     ! -- Scalars
@@ -292,225 +233,113 @@ subroutine dis_da(this)
     ! -- Connections
     call this%con%con_da()
     deallocate (this%con)
-    !
-    ! -- Return
-    return
   end subroutine dis_da
 
+  !> @brief Convert a user nodenumber to a string (nodenumber), (k,j), or (k,i,j)
   subroutine nodeu_to_string(this, nodeu, str)
-! ******************************************************************************
-! nodeu_to_string -- Convert user node number to a string in the form of
-! (nodenumber) or (k,i,j)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- dummy
     class(DisBaseType) :: this
     integer(I4B), intent(in) :: nodeu
     character(len=*), intent(inout) :: str
-    ! -- local
-! ------------------------------------------------------------------------------
-    !
-    call store_error('Program error: DisBaseType method nodeu_to_string not &
-                     &implemented.', terminate=.TRUE.)
-    !
-    ! -- return
-    return
+
+    call store_error('Programmer error: nodeu_to_string must be overridden', &
+                     terminate=.true.)
   end subroutine nodeu_to_string
 
+  !> @brief Convert a user nodenumber to an array (nodenumber), (k,j), or (k,i,j)
   subroutine nodeu_to_array(this, nodeu, arr)
-! ******************************************************************************
-! nodeu_to_array -- Convert user node number to cellid and fill array with
-!                   (nodenumber) or (k,j) or (k,i,j)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- dummy
     class(DisBaseType) :: this
     integer(I4B), intent(in) :: nodeu
     integer(I4B), dimension(:), intent(inout) :: arr
-    ! -- local
-! ------------------------------------------------------------------------------
-    !
-    call store_error('Program error: DisBaseType method nodeu_to_array not &
-                     &implemented.', terminate=.TRUE.)
-    !
-    ! -- return
-    return
+
+    call store_error('Programmer error: nodeu_to_array must be overridden', &
+                     terminate=.true.)
   end subroutine nodeu_to_array
 
+  !> @brief Convert a reduced nodenumber to a user node number
   function get_nodeuser(this, noder) result(nodenumber)
-! ******************************************************************************
-! get_nodeuser -- Return the user nodenumber from the reduced node number
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- return
-    integer(I4B) :: nodenumber
-    ! -- dummy
     class(DisBaseType) :: this
     integer(I4B), intent(in) :: noder
-! ------------------------------------------------------------------------------
-    !
+    integer(I4B) :: nodenumber
+
     if (this%nodes < this%nodesuser) then
       nodenumber = this%nodeuser(noder)
     else
       nodenumber = noder
     end if
-    !
-    ! -- return
-    return
   end function get_nodeuser
 
   function get_nodenumber_idx1(this, nodeu, icheck) result(nodenumber)
-! ******************************************************************************
-! get_nodenumber -- Return a nodenumber from the user specified node number
-!                   with an option to perform a check.  This subroutine
-!                   can be overridden by child classes to perform mapping
-!                   to a model node number
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use ConstantsModule, only: LINELENGTH
-    use SimModule, only: store_error
-    ! -- dummy
     class(DisBaseType), intent(in) :: this
     integer(I4B), intent(in) :: nodeu
     integer(I4B), intent(in) :: icheck
-    ! -- local
     integer(I4B) :: nodenumber
-! ------------------------------------------------------------------------------
-    !
+
     nodenumber = 0
-    call store_error('Program error: get_nodenumber_idx1 not implemented.', &
-                     terminate=.TRUE.)
-    !
-    ! -- return
-    return
+    call store_error('Programmer error: get_nodenumber_idx1 must be overridden', &
+                     terminate=.true.)
   end function get_nodenumber_idx1
 
   function get_nodenumber_idx2(this, k, j, icheck) result(nodenumber)
-! ******************************************************************************
-! get_nodenumber_idx2 -- This function should never be called.  It must be
-!   overridden by a child class.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use SimModule, only: store_error
-    ! -- dummy
     class(DisBaseType), intent(in) :: this
     integer(I4B), intent(in) :: k, j
     integer(I4B), intent(in) :: icheck
     integer(I4B) :: nodenumber
-! ------------------------------------------------------------------------------
-    !
+
     nodenumber = 0
-    call store_error('Program error: get_nodenumber_idx2 not implemented.', &
-                     terminate=.TRUE.)
-    !
-    ! -- Return
-    return
+    call store_error('Programmer error: get_nodenumber_idx2 must be overridden', &
+                     terminate=.true.)
   end function get_nodenumber_idx2
 
   function get_nodenumber_idx3(this, k, i, j, icheck) result(nodenumber)
-! ******************************************************************************
-! get_nodenumber_idx3 -- This function will not be invoked for an unstructured
-! model, but it may be from a Discretization3dType model.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    use SimModule, only: store_error
-    ! -- dummy
     class(DisBaseType), intent(in) :: this
     integer(I4B), intent(in) :: k, i, j
     integer(I4B), intent(in) :: icheck
     integer(I4B) :: nodenumber
-! ------------------------------------------------------------------------------
-    !
+
     nodenumber = 0
-    call store_error('Program error: get_nodenumber_idx3 not implemented.', &
-                     terminate=.TRUE.)
-    !
-    ! -- Return
-    return
+    call store_error('Programmer error: get_nodenumber_idx3 must be overridden', &
+                     terminate=.true.)
   end function get_nodenumber_idx3
 
+  !> @brief Get normal vector components between the cell and a given neighbor.
+  !! The normal points outward from the shared face between noden and nodem.
   subroutine connection_normal(this, noden, nodem, ihc, xcomp, ycomp, zcomp, &
                                ipos)
-! ******************************************************************************
-! connection_normal -- calculate the normal vector components for reduced
-!   nodenumber cell (noden) and its shared face with cell nodem.  ihc is the
-!   horizontal connection flag.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use SimModule, only: store_error
-    ! -- dummy
     class(DisBaseType) :: this
-    integer(I4B), intent(in) :: noden
-    integer(I4B), intent(in) :: nodem
-    integer(I4B), intent(in) :: ihc
+    integer(I4B), intent(in) :: noden !< cell (reduced nn)
+    integer(I4B), intent(in) :: nodem !< neighbor (reduced nn)
+    integer(I4B), intent(in) :: ihc !< horizontal connection flag
     real(DP), intent(inout) :: xcomp
     real(DP), intent(inout) :: ycomp
     real(DP), intent(inout) :: zcomp
     integer(I4B), intent(in) :: ipos
-! ------------------------------------------------------------------------------
-    !
-    call store_error('Program error: connection_normal not implemented.', &
-                     terminate=.TRUE.)
-    !
-    ! -- return
-    return
+
+    call store_error('Programmer error: connection_normal must be overridden', &
+                     terminate=.true.)
   end subroutine connection_normal
 
+  !> @brief Get unit vector components between the cell and a given neighbor.
+  !! Saturation must be provided to compute cell center vertical coordinates.
+  !! Also return the straight-line connection length.
   subroutine connection_vector(this, noden, nodem, nozee, satn, satm, ihc, &
                                xcomp, ycomp, zcomp, conlen)
-! ******************************************************************************
-! connection_vector -- calculate the unit vector components from reduced
-!   nodenumber cell (noden) to its neighbor cell (nodem).  The saturation for
-!   for these cells are also required so that the vertical position of the cell
-!   cell centers can be calculated.  ihc is the horizontal flag.  Also return
-!   the straight-line connection length.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use SimModule, only: store_error
-    ! -- dummy
     class(DisBaseType) :: this
-    integer(I4B), intent(in) :: noden
-    integer(I4B), intent(in) :: nodem
+    integer(I4B), intent(in) :: noden !< cell (reduced nn)
+    integer(I4B), intent(in) :: nodem !< neighbor (reduced nn)
     logical, intent(in) :: nozee
     real(DP), intent(in) :: satn
     real(DP), intent(in) :: satm
-    integer(I4B), intent(in) :: ihc
+    integer(I4B), intent(in) :: ihc !< horizontal connection flag
     real(DP), intent(inout) :: xcomp
     real(DP), intent(inout) :: ycomp
     real(DP), intent(inout) :: zcomp
     real(DP), intent(inout) :: conlen
-    ! -- local
-! ------------------------------------------------------------------------------
-    !
-    call store_error('Program error: connection_vector not implemented.', &
-                     terminate=.TRUE.)
-    !
-    ! -- return
-    return
+
+    call store_error('Programmer error: connection_vector must be overridden', &
+                     terminate=.true.)
   end subroutine connection_vector
 
-  !> @brief get the x,y for a node transformed into
-  !! 'global coordinates' using xorigin, yorigin, angrot,
-  !< analogously to how flopy does this.
+  !> @brief Get global (x, y) coordinates from cell-local coordinates.
   subroutine dis_transform_xy(x, y, xorigin, yorigin, angrot, xglo, yglo)
     real(DP), intent(in) :: x !< the cell-x coordinate to transform
     real(DP), intent(in) :: y !< the cell-y coordinate to transform
@@ -535,44 +364,31 @@ subroutine dis_transform_xy(x, y, xorigin, yorigin, angrot, xglo, yglo)
     ! then _translate_
     xglo = xglo + xorigin
     yglo = yglo + yorigin
-
   end subroutine dis_transform_xy
 
-  !> @brief return discretization type
-  !<
+  !> @brief Get the discretization type (DIS, DISV, or DISU)
   subroutine get_dis_type(this, dis_type)
     class(DisBaseType), intent(in) :: this
     character(len=*), intent(out) :: dis_type
 
-    ! suppress warning
     dis_type = "Not implemented"
-
-    call store_error('Program error: get_dis_type not implemented.', &
-                     terminate=.TRUE.)
-
+    call store_error('Programmer error: get_dis_type must be overridden', &
+                     terminate=.true.)
   end subroutine get_dis_type
 
-  subroutine allocate_scalars(this, name_model)
-! ******************************************************************************
-! allocate_scalars -- Allocate and initialize scalar variables in this class
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_allocate
+  !> @brief Allocate and initialize scalar variables
+  subroutine allocate_scalars(this, name_model, input_mempath)
     ! -- dummy
     class(DisBaseType) :: this
     character(len=*), intent(in) :: name_model
-    ! -- local
-! ------------------------------------------------------------------------------
+    character(len=*), intent(in) :: input_mempath
+    logical(LGP) :: found
     !
     ! -- Create memory path
     this%memoryPath = create_mem_path(name_model, 'DIS')
     !
     ! -- Allocate
     allocate (this%name_model)
-    allocate (this%input_mempath)
     allocate (this%input_fname)
     !
     call mem_allocate(this%inunit, 'INUNIT', this%memoryPath)
@@ -591,7 +407,7 @@ subroutine allocate_scalars(this, name_model)
     !
     ! -- Initialize
     this%name_model = name_model
-    this%input_mempath = ''
+    this%input_mempath = input_mempath
     this%input_fname = ''
     this%inunit = 0
     this%iout = 0
@@ -607,23 +423,15 @@ subroutine allocate_scalars(this, name_model)
     this%njas = 0
     this%lenuni = 0
     !
-    ! -- Return
-    return
+    ! -- update input filename
+    call mem_set_value(this%input_fname, 'INPUT_FNAME', &
+                       this%input_mempath, found)
   end subroutine allocate_scalars
 
+  !> @brief Allocate and initialize arrays
   subroutine allocate_arrays(this)
-! ******************************************************************************
-! allocate_arrays -- Read discretization information from file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use MemoryManagerModule, only: mem_allocate
-    ! -- dummy
     class(DisBaseType) :: this
     integer :: isize
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate
     call mem_allocate(this%mshape, this%ndim, 'MSHAPE', this%memoryPath)
@@ -646,23 +454,16 @@ subroutine allocate_arrays(this)
     ! -- Allocate the arrays
     call mem_allocate(this%dbuff, isize, 'DBUFF', this%name_model)
     call mem_allocate(this%ibuff, isize, 'IBUFF', this%name_model)
-    !
-    ! -- Return
-    return
   end subroutine allocate_arrays
 
+  !> @brief Convert a string to a user nodenumber.
+  !!
+  !! If DIS or DISV, read indices. If DISU, read user node number directly.
+  !! If flag_string is present and true, the first token may be
+  !! non-numeric (e.g. boundary name). In this case, return -2.
+  !<
   function nodeu_from_string(this, lloc, istart, istop, in, iout, line, &
                              flag_string, allow_zero) result(nodeu)
-! ******************************************************************************
-! nodeu_from_string -- Receive a string and convert the string to a user
-!   nodenumber.  The model is unstructured; just read user nodenumber.
-!   If flag_string argument is present and true, the first token in string
-!   is allowed to be a string (e.g. boundary name). In this case, if a string
-!   is encountered, return value as -2.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(DisBaseType) :: this
     integer(I4B), intent(inout) :: lloc
@@ -674,33 +475,22 @@ function nodeu_from_string(this, lloc, istart, istop, in, iout, line, &
     logical, optional, intent(in) :: flag_string
     logical, optional, intent(in) :: allow_zero
     integer(I4B) :: nodeu
-    ! -- local
-! ------------------------------------------------------------------------------
-    !
-    !
+
     nodeu = 0
-    call store_error('Program error: DisBaseType method nodeu_from_string &
-                     &not implemented.', terminate=.TRUE.)
-    !
-    ! -- return
-    return
+    call store_error('Programmer error: nodeu_from_string must be overridden', &
+                     terminate=.true.)
   end function nodeu_from_string
 
+  !> @brief Convert a cellid string to a user nodenumber.
+  !!
+  !! If flag_string is present and true, the first token may be
+  !! non-numeric (e.g. boundary name). In this case, return -2.
+  !!
+  !! If allow_zero is present and true, and all indices are zero, the
+  !! result can be zero. If allow_zero is false, a zero in any index is an error.
+  !<
   function nodeu_from_cellid(this, cellid, inunit, iout, flag_string, &
                              allow_zero) result(nodeu)
-! ******************************************************************************
-! nodeu_from_cellid -- Receive cellid as a string and convert the string to a
-!   user nodenumber.
-!   If flag_string argument is present and true, the first token in string
-!   is allowed to be a string (e.g. boundary name). In this case, if a string
-!   is encountered, return value as -2.
-!   If allow_zero argument is present and true, if all indices equal zero, the
-!   result can be zero. If allow_zero is false, a zero in any index causes an
-!   error.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(DisBaseType) :: this
     character(len=*), intent(inout) :: cellid
@@ -709,28 +499,21 @@ function nodeu_from_cellid(this, cellid, inunit, iout, flag_string, &
     logical, optional, intent(in) :: flag_string
     logical, optional, intent(in) :: allow_zero
     integer(I4B) :: nodeu
-! ------------------------------------------------------------------------------
-    !
+
     nodeu = 0
-    call store_error('Program error: DisBaseType method nodeu_from_cellid &
-                      &not implemented.', terminate=.TRUE.)
-    !
-    ! -- return
-    return
+    call store_error('Programmer error: nodeu_from_cellid must be overridden', &
+                     terminate=.true.)
   end function nodeu_from_cellid
 
+  !> @brief Convert a string to a reduced nodenumber.
+  !!
+  !! If the model is unstructured; just read user nodenumber.
+  !! If flag_string argument is present and true, the first token in string
+  !! is allowed to be a string (e.g. boundary name). In this case, if a string
+  !! is encountered, return value as -2.
+  !<
   function noder_from_string(this, lloc, istart, istop, in, iout, line, &
                              flag_string) result(noder)
-! ******************************************************************************
-! noder_from_string -- Receive a string and convert the string to a reduced
-!   nodenumber.  The model is unstructured; just read user nodenumber.
-!   If flag_string argument is present and true, the first token in string
-!   is allowed to be a string (e.g. boundary name). In this case, if a string
-!   is encountered, return value as -2.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(DisBaseType) :: this
     integer(I4B), intent(inout) :: lloc
@@ -745,7 +528,6 @@ function noder_from_string(this, lloc, istart, istop, in, iout, line, &
     integer(I4B) :: nodeu
     character(len=LINELENGTH) :: nodestr
     logical :: flag_string_local
-! ------------------------------------------------------------------------------
     !
     if (present(flag_string)) then
       flag_string_local = flag_string
@@ -768,26 +550,18 @@ function noder_from_string(this, lloc, istart, istop, in, iout, line, &
         trim(adjustl(nodestr))
       call store_error(errmsg)
     end if
-    !
-    ! -- return
-    return
   end function noder_from_string
 
+  !> @brief Convert cellid string to reduced nodenumber
+  !!
+  !! If flag_string argument is present and true, the first token in string
+  !! is allowed to be a string (e.g. boundary name). In this case, if a string
+  !! is encountered, return value as -2.
+  !! If allow_zero argument is present and true, if all indices equal zero, the
+  !! result can be zero. If allow_zero is false, a zero in any index is an error.
+  !<
   function noder_from_cellid(this, cellid, inunit, iout, flag_string, &
                              allow_zero) result(noder)
-! ******************************************************************************
-! noder_from_cellid -- Receive cellid as a string and convert it to a reduced
-!   nodenumber.
-!   If flag_string argument is present and true, the first token in string
-!   is allowed to be a string (e.g. boundary name). In this case, if a string
-!   is encountered, return value as -2.
-!   If allow_zero argument is present and true, if all indices equal zero, the
-!   result can be zero. If allow_zero is false, a zero in any index causes an
-!   error.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     integer(I4B) :: noder
     ! -- dummy
@@ -802,7 +576,6 @@ function noder_from_cellid(this, cellid, inunit, iout, flag_string, &
     logical :: allowzerolocal
     character(len=LINELENGTH) :: nodestr
     logical :: flag_string_local
-! ------------------------------------------------------------------------------
     !
     if (present(flag_string)) then
       flag_string_local = flag_string
@@ -831,61 +604,28 @@ function noder_from_cellid(this, cellid, inunit, iout, flag_string, &
         trim(adjustl(nodestr))
       call store_error(errmsg)
     end if
-    !
-    ! -- return
-    return
   end function noder_from_cellid
 
+  !> @brief Indicates whether the grid discretization supports layers.
   logical function supports_layers(this)
-! ******************************************************************************
-! supports_layers
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- dummy
     class(DisBaseType) :: this
-! ------------------------------------------------------------------------------
-    !
-    !
     supports_layers = .false.
-    call store_error('Program error: DisBaseType method supports_layers not &
-                     &implemented.', terminate=.TRUE.)
-    return
+    call store_error('Programmer error: supports_layers must be overridden', &
+                     terminate=.true.)
   end function supports_layers
 
+  !> @brief Return number of cells per layer.
+  !! This is nodes for a DISU grid, as there are no layers.
   function get_ncpl(this)
-! ******************************************************************************
-! get_ncpl -- Return number of cells per layer.  This is nodes
-!   for a DISU grid, as there are no layers.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    ! -- return
     integer(I4B) :: get_ncpl
-    ! -- dummy
     class(DisBaseType) :: this
-! ------------------------------------------------------------------------------
-    !
-    !
     get_ncpl = 0
-    call store_error('Program error: DisBaseType method get_ncpl not &
-                     &implemented.', terminate=.TRUE.)
-    !
-    ! -- Return
-    return
+    call store_error('Programmer error: get_ncpl must be overridden', &
+                     terminate=.true.)
   end function get_ncpl
 
+  !> @brief Return volume of cell n based on x value passed.
   function get_cell_volume(this, n, x)
-! ******************************************************************************
-! get_cell_volume -- Return volume of cell n based on x value passed.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- return
     real(DP) :: get_cell_volume
     ! -- dummy
@@ -897,27 +637,30 @@ function get_cell_volume(this, n, x)
     real(DP) :: bt
     real(DP) :: sat
     real(DP) :: thick
-! ------------------------------------------------------------------------------
-    !
+
     get_cell_volume = DZERO
     tp = this%top(n)
     bt = this%bot(n)
     sat = sQuadraticSaturation(tp, bt, x)
     thick = (tp - bt) * sat
     get_cell_volume = this%area(n) * thick
-    !
-    ! -- Return
-    return
   end function get_cell_volume
 
+  !> @brief Get a 2D array of polygon vertices, listed in
+  !! clockwise order beginning with the lower left corner.
+  subroutine get_polyverts(this, ic, polyverts, closed)
+    class(DisBaseType), intent(inout) :: this
+    integer(I4B), intent(in) :: ic !< cell number (reduced)
+    real(DP), allocatable, intent(out) :: polyverts(:, :) !< polygon vertices (column-major indexing)
+    logical(LGP), intent(in), optional :: closed !< whether to close the polygon, duplicating a vertex
+
+    errmsg = 'Programmer error: get_polyverts must be overridden'
+    call store_error(errmsg, terminate=.true.)
+  end subroutine
+
+  !> @brief Read an integer array
   subroutine read_int_array(this, line, lloc, istart, istop, iout, in, &
                             iarray, aname)
-! ******************************************************************************
-! read_int_array -- Read a GWF integer array
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(DisBaseType), intent(inout) :: this
     character(len=*), intent(inout) :: line
@@ -928,24 +671,14 @@ subroutine read_int_array(this, line, lloc, istart, istop, iout, in, &
     integer(I4B), intent(in) :: iout
     integer(I4B), dimension(:), pointer, contiguous, intent(inout) :: iarray
     character(len=*), intent(in) :: aname
-    !
-    ! -- store error
-    errmsg = 'Programmer error: read_int_array needs to be overridden &
-            &in any DIS type that extends DisBaseType'
-    call store_error(errmsg, terminate=.TRUE.)
-    !
-    ! -- return
-    return
+
+    errmsg = 'Programmer error: read_int_array must be overridden'
+    call store_error(errmsg, terminate=.true.)
   end subroutine read_int_array
 
+  !> @brief Read a double precision array
   subroutine read_dbl_array(this, line, lloc, istart, istop, iout, in, &
                             darray, aname)
-! ******************************************************************************
-! read_dbl_array -- Read a GWF double precision array
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(DisBaseType), intent(inout) :: this
     character(len=*), intent(inout) :: line
@@ -956,23 +689,13 @@ subroutine read_dbl_array(this, line, lloc, istart, istop, iout, in, &
     integer(I4B), intent(in) :: iout
     real(DP), dimension(:), pointer, contiguous, intent(inout) :: darray
     character(len=*), intent(in) :: aname
-    !
-    ! -- str=ore error message
-    errmsg = 'Programmer error: read_dbl_array needs to be overridden &
-            &in any DIS type that extends DisBaseType'
-    call store_error(errmsg, terminate=.TRUE.)
-    !
-    ! -- return
-    return
+
+    errmsg = 'Programmer error: read_dbl_array must be overridden'
+    call store_error(errmsg, terminate=.true.)
   end subroutine read_dbl_array
 
+  !> @brief Fill an integer array
   subroutine fill_int_array(this, ibuff1, ibuff2)
-! ******************************************************************************
-! fill_dbl_array -- Fill a GWF integer array
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(DisBaseType), intent(inout) :: this
     integer(I4B), dimension(:), pointer, contiguous, intent(in) :: ibuff1
@@ -980,24 +703,16 @@ subroutine fill_int_array(this, ibuff1, ibuff2)
     ! -- local
     integer(I4B) :: nodeu
     integer(I4B) :: noder
-! ------------------------------------------------------------------------------
+
     do nodeu = 1, this%nodesuser
       noder = this%get_nodenumber(nodeu, 0)
       if (noder <= 0) cycle
       ibuff2(noder) = ibuff1(nodeu)
     end do
-    !
-    ! -- return
-    return
   end subroutine fill_int_array
 
+  !> @brief Fill a double precision array
   subroutine fill_dbl_array(this, buff1, buff2)
-! ******************************************************************************
-! fill_dbl_array -- Fill a GWF double precision array
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(DisBaseType), intent(inout) :: this
     real(DP), dimension(:), pointer, contiguous, intent(in) :: buff1
@@ -1005,33 +720,28 @@ subroutine fill_dbl_array(this, buff1, buff2)
     ! -- local
     integer(I4B) :: nodeu
     integer(I4B) :: noder
-! ------------------------------------------------------------------------------
+
     do nodeu = 1, this%nodesuser
       noder = this%get_nodenumber(nodeu, 0)
       if (noder <= 0) cycle
       buff2(noder) = buff1(nodeu)
     end do
-    !
-    ! -- return
-    return
   end subroutine fill_dbl_array
 
-  subroutine read_list(this, in, iout, iprpak, nlist, inamedbound, &
-                       iauxmultcol, nodelist, rlist, auxvar, auxname, &
-                       boundname, label, pkgname, tsManager, iscloc, &
+  !> @brief Read a list using the list reader.
+  !!
+  !! Convert user node numbers to reduced numbers.
+  !! Terminate if any nodenumbers are within an inactive domain.
+  !! Set up time series and multiply by iauxmultcol if it exists.
+  !! Write the list to iout if iprpak is set.
+  !<
+  subroutine read_list(this, line_reader, in, iout, iprpak, nlist, &
+                       inamedbound, iauxmultcol, nodelist, rlist, auxvar, &
+                       auxname, boundname, label, pkgname, tsManager, iscloc, &
                        indxconvertflux)
-! ******************************************************************************
-! read_list -- Read a list using the list reader object.
-!              Convert user node numbers to reduced numbers.
-!              Terminate if any nodenumbers are within an inactive domain.
-!              Set up time series and multiply by iauxmultcol if it exists.
-!              Write the list to iout if iprpak is set.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LENBOUNDNAME, LINELENGTH
+    use LongLineReaderModule, only: LongLineReaderType
     use ListReaderModule, only: ListReaderType
     use SimModule, only: store_error, store_error_unit, count_errors
     use InputOutputModule, only: urword
@@ -1039,6 +749,7 @@ subroutine read_list(this, in, iout, iprpak, nlist, inamedbound, &
     use TimeSeriesManagerModule, only: read_value_or_time_series
     ! -- dummy
     class(DisBaseType) :: this
+    type(LongLineReaderType), intent(inout) :: line_reader
     integer(I4B), intent(in) :: in
     integer(I4B), intent(in) :: iout
     integer(I4B), intent(in) :: iprpak
@@ -1051,8 +762,6 @@ subroutine read_list(this, in, iout, iprpak, nlist, inamedbound, &
     character(len=LENAUXNAME), dimension(:), intent(inout) :: auxname
     character(len=LENBOUNDNAME), dimension(:), pointer, contiguous, &
       intent(inout) :: boundname
-    !character(len=:), dimension(:), pointer, contiguous, intent(inout) :: auxname
-    !character(len=:), dimension(:), pointer, contiguous, intent(inout) :: boundname
     character(len=*), intent(in) :: label
     character(len=*), intent(in) :: pkgName
     type(TimeSeriesManagerType) :: tsManager
@@ -1067,11 +776,11 @@ subroutine read_list(this, in, iout, iprpak, nlist, inamedbound, &
     type(ListReaderType) :: lstrdobj
     type(TimeSeriesLinkType), pointer :: tsLinkBnd => null()
     type(TimeSeriesLinkType), pointer :: tsLinkAux => null()
-! ------------------------------------------------------------------------------
     !
     ! -- Read the list
-    call lstrdobj%read_list(in, iout, nlist, inamedbound, this%mshape, &
-                            nodelist, rlist, auxvar, auxname, boundname, label)
+    call lstrdobj%read_list(line_reader, in, iout, nlist, inamedbound, &
+                            this%mshape, nodelist, rlist, auxvar, auxname, &
+                            boundname, label)
     !
     ! -- Go through all locations where a text string was found instead of
     !    a double precision value and make time-series links to rlist
@@ -1167,21 +876,15 @@ subroutine read_list(this, in, iout, iprpak, nlist, inamedbound, &
         call store_error_unit(in)
       end if
     end if
-    !
-    ! -- return
   end subroutine read_list
 
+  !> @brief Read a 2d double array into col icolbnd of darray.
+  !!
+  !! For cells that are outside of the active domain,
+  !! do not copy the array value into darray.
+  !<
   subroutine read_layer_array(this, nodelist, darray, ncolbnd, maxbnd, &
                               icolbnd, aname, inunit, iout)
-! ******************************************************************************
-! read_layer_array -- Read a 2d double array into col icolbnd of darray.
-!                     For cells that are outside of the active domain,
-!                     do not copy the array value into darray.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(DisBaseType) :: this
     integer(I4B), intent(in) :: ncolbnd
@@ -1192,65 +895,36 @@ subroutine read_layer_array(this, nodelist, darray, ncolbnd, maxbnd, &
     character(len=*), intent(in) :: aname
     integer(I4B), intent(in) :: inunit
     integer(I4B), intent(in) :: iout
-    !
-    !
-    errmsg = 'Programmer error: read_layer_array needs to be overridden &
-            &in any DIS type that extends DisBaseType'
-    call store_error(errmsg, terminate=.TRUE.)
-    !
-    ! -- return
+
+    errmsg = 'Programmer error: read_layer_array must be overridden'
+    call store_error(errmsg, terminate=.true.)
   end subroutine read_layer_array
 
+  !> @brief Record a double precision array.
+  !!
+  !! The array is written to a formatted or unformatted external file
+  !! depending on the arguments.
   subroutine record_array(this, darray, iout, iprint, idataun, aname, &
                           cdatafmp, nvaluesp, nwidthp, editdesc, dinact)
-! ******************************************************************************
-! record_array -- Record a double precision array.  The array will be
-!   printed to an external file and/or written to an unformatted external file
-!   depending on the argument specifications.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-!      darray is the double precision array to record
-!      iout is the unit number for ascii output
-!      iprint is a flag indicating whether or not to print the array
-!      idataun is the unit number to which the array will be written in binary
-!        form; if negative then do not write by layers, write entire array
-!      aname is the text descriptor of the array
-!      cdatafmp is the fortran format for writing the array
-!      nvaluesp is the number of values per line for printing
-!      nwidthp is the width of the number for printing
-!      editdesc is the format type (I, G, F, S, E)
-!      dinact is the double precision value to use for cells that are excluded
-!        from the model domain
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(DisBaseType), intent(inout) :: this
-    real(DP), dimension(:), pointer, contiguous, intent(inout) :: darray
-    integer(I4B), intent(in) :: iout
-    integer(I4B), intent(in) :: iprint
-    integer(I4B), intent(in) :: idataun
-    character(len=*), intent(in) :: aname
-    character(len=*), intent(in) :: cdatafmp
-    integer(I4B), intent(in) :: nvaluesp
-    integer(I4B), intent(in) :: nwidthp
-    character(len=*), intent(in) :: editdesc
-    real(DP), intent(in) :: dinact
-    !
-    ! --
-    errmsg = 'Programmer error: record_array needs to be overridden &
-            &in any DIS type that extends DisBaseType'
-    call store_error(errmsg, terminate=.TRUE.)
-    !
+    real(DP), dimension(:), pointer, contiguous, intent(inout) :: darray !< double precision array to record
+    integer(I4B), intent(in) :: iout !< ascii output unit number
+    integer(I4B), intent(in) :: iprint !< whether to print the array
+    integer(I4B), intent(in) :: idataun !< binary output unit number
+    character(len=*), intent(in) :: aname !< text descriptor
+    character(len=*), intent(in) :: cdatafmp !< write format
+    integer(I4B), intent(in) :: nvaluesp !< values per line
+    integer(I4B), intent(in) :: nwidthp !< number width
+    character(len=*), intent(in) :: editdesc !< format type (I, G, F, S, E)
+    real(DP), intent(in) :: dinact !< double precision value for cells excluded from model domain
+
+    errmsg = 'Programmer error: record_array must be overridden'
+    call store_error(errmsg, terminate=.true.)
   end subroutine record_array
 
+  !> @brief Record a connection-based double precision array
   subroutine record_connection_array(this, flowja, ibinun, iout)
-! ******************************************************************************
-! record_connection_array -- Record a connection-based double precision
-! array for either a structured or an unstructured grid.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(DisBaseType) :: this
     real(DP), dimension(:), intent(in) :: flowja
@@ -1260,74 +934,42 @@ subroutine record_connection_array(this, flowja, ibinun, iout)
     character(len=16), dimension(1) :: text
     ! -- data
     data text(1)/'    FLOW-JA-FACE'/
-! ------------------------------------------------------------------------------
-    !
+
     ! -- write full ja array
     call ubdsv1(kstp, kper, text(1), ibinun, flowja, size(flowja), 1, 1, &
                 iout, delt, pertim, totim)
-    !
-    ! -- return
-    return
   end subroutine record_connection_array
 
+  !> @brief Convert reduced node number to string (nodenumber), (k,j) or (k,i,j)
   subroutine noder_to_string(this, noder, str)
-! ******************************************************************************
-! noder_to_string -- Convert reduced node number to a string in the form of
-! (nodenumber) or (k,i,j)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(DisBaseType) :: this
     integer(I4B), intent(in) :: noder
     character(len=*), intent(inout) :: str
     ! -- local
     integer(I4B) :: nodeu
-! ------------------------------------------------------------------------------
-    !
+
     nodeu = this%get_nodeuser(noder)
     call this%nodeu_to_string(nodeu, str)
-    !
-    ! -- return
-    return
   end subroutine noder_to_string
 
+  !> @brief Convert reduced node number to array (nodenumber), (k,j) or (k,i,j)
   subroutine noder_to_array(this, noder, arr)
-! ******************************************************************************
-! noder_to_array -- Convert reduced node number to cellid and fill array with
-!                   (nodenumber) or (k,j) or (k,i,j)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(DisBaseType) :: this
     integer(I4B), intent(in) :: noder
     integer(I4B), dimension(:), intent(inout) :: arr
     ! -- local
     integer(I4B) :: nodeu
-! ------------------------------------------------------------------------------
-    !
+
     nodeu = this%get_nodeuser(noder)
     call this%nodeu_to_array(nodeu, arr)
-    !
-    ! -- return
-    return
   end subroutine noder_to_array
 
+  !> @brief Record list header for imeth=6
   subroutine record_srcdst_list_header(this, text, textmodel, textpackage, &
                                        dstmodel, dstpackage, naux, auxtxt, &
                                        ibdchn, nlist, iout)
-! ******************************************************************************
-! record_srcdst_list_header -- Record list header for imeth=6
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- dummy
     class(DisBaseType) :: this
     character(len=16), intent(in) :: text
     character(len=16), intent(in) :: textmodel
@@ -1339,26 +981,14 @@ subroutine record_srcdst_list_header(this, text, textmodel, textpackage, &
     integer(I4B), intent(in) :: ibdchn
     integer(I4B), intent(in) :: nlist
     integer(I4B), intent(in) :: iout
-    !
-    ! --
-    errmsg = 'Programmer error: record_srcdst_list_header needs to be &
-            &overridden in any DIS type that extends DisBaseType'
-    call store_error(errmsg, terminate=.TRUE.)
-    !
-    ! -- return
-    return
+
+    errmsg = 'Programmer error: record_srcdst_list_header must be overridden'
+    call store_error(errmsg, terminate=.true.)
   end subroutine record_srcdst_list_header
 
+  !> @brief Record list header
   subroutine record_srcdst_list_entry(this, ibdchn, noder, noder2, q, &
                                       naux, aux, olconv, olconv2)
-! ******************************************************************************
-! record_srcdst_list_header -- Record list header
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use InputOutputModule, only: ubdsvd
     ! -- dummy
     class(DisBaseType) :: this
     integer(I4B), intent(in) :: ibdchn
@@ -1374,13 +1004,12 @@ subroutine record_srcdst_list_entry(this, ibdchn, noder, noder2, q, &
     logical :: lconv2
     integer(I4B) :: nodeu
     integer(I4B) :: nodeu2
-! ------------------------------------------------------------------------------
     !
     ! -- Use ubdsvb to write list header
     if (present(olconv)) then
       lconv = olconv
     else
-      lconv = .TRUE.
+      lconv = .true.
     end if
     if (lconv) then
       nodeu = this%get_nodeuser(noder)
@@ -1390,7 +1019,7 @@ subroutine record_srcdst_list_entry(this, ibdchn, noder, noder2, q, &
     if (present(olconv2)) then
       lconv2 = olconv2
     else
-      lconv2 = .TRUE.
+      lconv2 = .true.
     end if
     if (lconv2) then
       nodeu2 = this%get_nodeuser(noder2)
@@ -1398,49 +1027,26 @@ subroutine record_srcdst_list_entry(this, ibdchn, noder, noder2, q, &
       nodeu2 = noder2
     end if
     call ubdsvd(ibdchn, nodeu, nodeu2, q, naux, aux)
-    !
-    ! -- return
-    return
   end subroutine record_srcdst_list_entry
 
-  subroutine nlarray_to_nodelist(this, nodelist, maxbnd, nbound, aname, &
-                                 inunit, iout)
-! ******************************************************************************
-! nlarray_to_nodelist -- Read an integer array into nodelist. For structured
-!                        model, integer array is layer number; for unstructured
-!                        model, integer array is node number.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    use SimModule, only: store_error
-    use ConstantsModule, only: LINELENGTH
-    ! -- dummy
+  !> @brief Convert an integer array to nodelist.
+  !!
+  !! For DIS/DISV, the array is layer number, for DISU it's node number.
+  !<
+  subroutine nlarray_to_nodelist(this, darray, nodelist, maxbnd, nbound, aname)
     class(DisBaseType) :: this
     integer(I4B), intent(in) :: maxbnd
+    integer(I4B), dimension(:), pointer, contiguous :: darray
     integer(I4B), dimension(maxbnd), intent(inout) :: nodelist
     integer(I4B), intent(inout) :: nbound
     character(len=*), intent(in) :: aname
-    integer(I4B), intent(in) :: inunit
-    integer(I4B), intent(in) :: iout
-    !
-    ! --
-    errmsg = 'Programmer error: nlarray_to_nodelist needs to be &
-            &overridden in any DIS type that extends DisBaseType'
-    call store_error(errmsg, terminate=.TRUE.)
-    !
-    ! -- return
-    return
+
+    errmsg = 'Programmer error: nlarray_to_nodelist must be overridden'
+    call store_error(errmsg, terminate=.true.)
   end subroutine nlarray_to_nodelist
 
+  !> @brief Find the first highest active cell beneath cell n
   subroutine highest_active(this, n, ibound)
-! ******************************************************************************
-! highest_active -- Find the first highest active cell beneath cell n
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(DisBaseType) :: this
     integer(I4B), intent(inout) :: n
@@ -1448,7 +1054,6 @@ subroutine highest_active(this, n, ibound)
     ! -- locals
     integer(I4B) :: m, ii, iis
     logical done, bottomcell
-! ------------------------------------------------------------------------------
     !
     ! -- Loop through connected cells until the highest active one (including a
     !    constant head cell) is found.  Return that cell as n.
@@ -1476,30 +1081,43 @@ subroutine highest_active(this, n, ibound)
       end do cloop
       if (bottomcell) done = .true.
     end do
-    !
-    ! -- return
-    return
   end subroutine highest_active
 
+  !> @brief Return the cell area for the given node
   function get_area(this, node) result(area)
-! ******************************************************************************
-! get_area -- Return the cell area for this node
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- return
+    class(DisBaseType) :: this
+    integer(I4B), intent(in) :: node !< reduced node number
     real(DP) :: area
+
+    area = this%area(node)
+  end function get_area
+
+  !> @ brief Calculate the area factor for the cell connection
+  !!
+  !!  Function calculates the area factor for the cell connection. The sum of
+  !!  all area factors for all cell connections to overlying or underlying
+  !!  cells cells will be 1.
+  !!
+  !!  TODO: confirm that this works for cells that are only partially covered
+  !!        by overlying or underlying cells.
+  !<
+  function get_area_factor(this, node, idx_conn) result(area_factor)
+    ! -- return
+    real(DP) :: area_factor !< connection cell area factor
     ! -- dummy
     class(DisBaseType) :: this
-    integer(I4B), intent(in) :: node
-! ------------------------------------------------------------------------------
+    integer(I4B), intent(in) :: node !< cell node number
+    integer(I4B), intent(in) :: idx_conn !< connection index
+    ! -- local
+    real(DP) :: area_node
+    real(DP) :: area_conn
     !
-    ! -- Return the cell area
-    area = this%area(node)
+    ! -- calculate the cell area fraction
+    area_node = this%area(node)
+    area_conn = this%con%hwva(idx_conn)
     !
-    ! -- return
-    return
-  end function get_area
+    ! -- return the cell area factor
+    area_factor = area_conn / area_node
+  end function get_area_factor
 
 end module BaseDisModule
diff --git a/src/Model/ModelUtilities/DisvGeom.f90 b/src/Model/ModelUtilities/DisvGeom.f90
index 581ad424b88..e935afad6fd 100644
--- a/src/Model/ModelUtilities/DisvGeom.f90
+++ b/src/Model/ModelUtilities/DisvGeom.f90
@@ -1,13 +1,14 @@
 module DisvGeom
 
   use KindModule, only: DP, I4B
-  use InputOutputModule, only: get_node, get_jk
+  use GeomUtilModule, only: get_node, get_jk
   implicit none
   private
   public :: DisvGeomType
   public :: line_unit_vector
 
   type DisvGeomType
+
     integer(I4B) :: k
     integer(I4B) :: j
     integer(I4B) :: nodeusr
@@ -26,7 +27,9 @@ module DisvGeom
     real(DP), pointer, dimension(:, :) :: cellxy_grid => null()
     integer(I4B), pointer, dimension(:, :) :: nodereduced => null() ! nodered = nodereduced(nodeusr)
     integer(I4B), pointer, dimension(:) :: nodeuser => null() ! nodeusr = nodesuser(nodered)
+
   contains
+
     procedure :: init
     generic :: set => set_kj, set_nodered
     procedure :: set_kj
@@ -37,12 +40,16 @@ module DisvGeom
     procedure :: connection_vector
     procedure :: shares_edge
     procedure :: get_area
+
   end type DisvGeomType
 
 contains
 
+  !> @brief Initialize
+  !<
   subroutine init(this, nlay, ncpl, nodes, top_grid, bot_grid, iavert, &
                   javert, vertex_grid, cellxy_grid, nodereduced, nodeuser)
+    ! -- dummy
     class(DisvGeomType) :: this
     integer(I4B), intent(in) :: nlay
     integer(I4B), intent(in) :: ncpl
@@ -57,6 +64,7 @@ subroutine init(this, nlay, ncpl, nodes, top_grid, bot_grid, iavert, &
     integer(I4B), dimension(nodes), target :: nodeuser
     ! -- local
     integer(I4B) :: nodesuser
+    !
     this%nlay = nlay
     this%ncpl = ncpl
     this%nodes = nodes
@@ -69,6 +77,7 @@ subroutine init(this, nlay, ncpl, nodes, top_grid, bot_grid, iavert, &
     this%nodereduced => nodereduced
     this%nodeuser => nodeuser
     nodesuser = ncpl * nlay
+    !
     if (nodes < nodesuser) then
       this%reduced = .true.
     else
@@ -76,10 +85,14 @@ subroutine init(this, nlay, ncpl, nodes, top_grid, bot_grid, iavert, &
     end if
   end subroutine init
 
+  !> @brief Set node IDs
+  !<
   subroutine set_kj(this, k, j)
+    ! -- dummy
     class(DisvGeomType) :: this
     integer(I4B), intent(in) :: k
     integer(I4B), intent(in) :: j
+    !
     this%k = k
     this%j = j
     this%nodeusr = get_node(k, 1, j, this%nlay, 1, this%ncpl)
@@ -89,25 +102,39 @@ subroutine set_kj(this, k, j)
       this%nodered = this%nodeusr
     end if
     call this%cell_setup()
+    !
+    ! -- Return
     return
   end subroutine set_kj
 
+  !> @brief Set reduced node number
+  !<
   subroutine set_nodered(this, nodered)
+    ! -- dummy
     class(DisvGeomType) :: this
     integer(I4B), intent(in) :: nodered
+    !
     this%nodered = nodered
+    !
     if (this%reduced) then
       this%nodeusr = this%nodeuser(nodered)
     else
       this%nodeusr = nodered
     end if
+    !
     call get_jk(this%nodeusr, this%ncpl, this%nlay, this%j, this%k)
     call this%cell_setup()
+    !
+    ! -- Return
     return
   end subroutine set_nodered
 
+  !> @brief Set top and bottom elevations of grid cell
+  !<
   subroutine cell_setup(this)
+    ! -- dummy
     class(DisvGeomType) :: this
+    !
     this%top = this%top_grid(this%nodered)
     this%bot = this%bot_grid(this%nodered)
   end subroutine cell_setup
@@ -115,6 +142,7 @@ end subroutine cell_setup
   subroutine cprops(this, cell2, hwva, cl1, cl2, ax, ihc)
     ! -- module
     use ConstantsModule, only: DZERO, DHALF, DONE
+    ! -- dummy
     class(DisvGeomType) :: this
     type(DisvGeomType) :: cell2
     real(DP), intent(out) :: hwva
@@ -177,12 +205,14 @@ subroutine cprops(this, cell2, hwva, cl1, cl2, ax, ihc)
         ax = anglex(x1, y1, x2, y2)
       end if
     end if
+    !
+    ! -- Return
     return
   end subroutine cprops
 
+  !> @brief Return the x and y components of an outward normal facing vector
+  !<
   subroutine edge_normal(this, cell2, xcomp, ycomp)
-    ! return the x and y components of an outward normal
-    ! facing vector
     ! -- module
     use ConstantsModule, only: DZERO, DHALF, DONE
     ! -- dummy
@@ -208,14 +238,17 @@ subroutine edge_normal(this, cell2, xcomp, ycomp)
     y2 = this%vertex_grid(2, ivert2)
     !
     call line_unit_normal(x1, y1, x2, y2, xcomp, ycomp)
+    !
+    ! -- Return
     return
   end subroutine edge_normal
 
+  !> @brief Return the x y and z components of a unit vector that points from
+  !! from the center of this to the center of cell2, and the straight-line
+  !! connection length
+  !<
   subroutine connection_vector(this, cell2, nozee, satn, satm, xcomp, &
                                ycomp, zcomp, conlen)
-    ! return the x y and z components of a unit vector that points
-    ! from the center of this to the center of cell2, and the
-    ! straight-line connection length
     ! -- module
     use ConstantsModule, only: DZERO, DHALF, DONE
     ! -- dummy
@@ -245,22 +278,23 @@ subroutine connection_vector(this, cell2, nozee, satn, satm, xcomp, &
     !
     call line_unit_vector(x1, y1, z1, x2, y2, z2, xcomp, ycomp, zcomp, &
                           conlen)
+    !
+    ! -- Return
     return
   end subroutine connection_vector
 
+  !> @brief Return true if this shares a horizontal edge with cell2
+  !<
   function shares_edge(this, cell2) result(l)
-! ******************************************************************************
-! shares_edge -- Return true if this shares a horizontal edge with cell2
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     class(DisvGeomType) :: this
     type(DisvGeomType) :: cell2
+    ! -- return
     logical l
+    ! -- local
     integer(I4B) :: istart1, istop1, istart2, istop2
     integer(I4B) :: ivert1, ivert2
-! ------------------------------------------------------------------------------
+    !
     istart1 = this%iavert(this%j)
     istop1 = this%iavert(this%j + 1) - 1
     istart2 = cell2%iavert(cell2%j)
@@ -272,30 +306,29 @@ function shares_edge(this, cell2) result(l)
     if (ivert1 == 0 .or. ivert2 == 0) then
       l = .false.
     end if
+    !
+    ! -- Return
     return
   end function shares_edge
 
+  !> @brief Find two common vertices shared by cell1 and cell2.
+  !!
+  !! Return 0 if there are no shared edges.  Proceed forward through ivlist1
+  !! and backward through ivlist2 as a clockwise face in cell1 must correspond
+  !! to a counter clockwise face in cell2.
+  !<
   subroutine shared_edge(ivlist1, ivlist2, ivert1, ivert2)
-! ******************************************************************************
-! shared_edge -- Find two common vertices shared by cell1 and cell2.
-!                ivert1 and ivert2 will return with 0 if there are
-!                no shared edges.  Proceed forward through ivlist1 and
-!                backward through ivlist2 as a clockwise face in cell1
-!                must correspond to a counter clockwise face in cell2
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     integer(I4B), dimension(:) :: ivlist1
     integer(I4B), dimension(:) :: ivlist2
     integer(I4B), intent(out) :: ivert1
     integer(I4B), intent(out) :: ivert2
+    ! -- local
     integer(I4B) :: nv1
     integer(I4B) :: nv2
     integer(I4B) :: il1
     integer(I4B) :: il2
     logical :: found
-! ------------------------------------------------------------------------------
     !
     found = .false.
     nv1 = size(ivlist1)
@@ -316,15 +349,12 @@ subroutine shared_edge(ivlist1, ivlist2, ivert1, ivert2)
     end do outerloop
   end subroutine shared_edge
 
+  !> @brief Calculate and return the area of the cell
+  !!
+  !! a = 1/2 *[(x1*y2 + x2*y3 + x3*y4 + ... + xn*y1) -
+  !!             (x2*y1 + x3*y2 + x4*y3 + ... + x1*yn)]
+  !<
   function get_area(this) result(area)
-! ******************************************************************************
-! get_cell2d_area -- Calculate and return the area of the cell
-!   a = 1/2 *[(x1*y2 + x2*y3 + x3*y4 + ... + xn*y1) -
-!             (x2*y1 + x3*y2 + x4*y3 + ... + x1*yn)]
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- module
     use ConstantsModule, only: DZERO, DHALF
     ! -- dummy
@@ -335,13 +365,18 @@ function get_area(this) result(area)
     integer(I4B) :: ivert
     integer(I4B) :: nvert
     integer(I4B) :: icount
+    integer(I4B) :: iv1
     real(DP) :: x
     real(DP) :: y
-! ------------------------------------------------------------------------------
+    real(DP) :: x1
+    real(DP) :: y1
     !
     area = DZERO
     nvert = this%iavert(this%j + 1) - this%iavert(this%j)
     icount = 1
+    iv1 = this%javert(this%iavert(this%j))
+    x1 = this%vertex_grid(1, iv1)
+    y1 = this%vertex_grid(2, iv1)
     do ivert = this%iavert(this%j), this%iavert(this%j + 1) - 1
       x = this%vertex_grid(1, this%javert(ivert))
       if (icount < nvert) then
@@ -349,7 +384,7 @@ function get_area(this) result(area)
       else
         y = this%vertex_grid(2, this%javert(this%iavert(this%j)))
       end if
-      area = area + x * y
+      area = area + (x - x1) * (y - y1)
       icount = icount + 1
     end do
     !
@@ -361,114 +396,116 @@ function get_area(this) result(area)
       else
         x = this%vertex_grid(1, this%javert(this%iavert(this%j)))
       end if
-      area = area - x * y
+      area = area - (x - x1) * (y - y1)
       icount = icount + 1
     end do
     !
     area = abs(area) * DHALF
     !
-    ! -- return
+    ! -- Return
     return
   end function get_area
 
+  !> @brief Calculate the angle that the x-axis makes with a line that is
+  !! normal to the two points.
+  !!
+  !! This assumes that vertices are numbered clockwise so that the angle is for
+  !! the normal outward of cell n.
+  !<
   function anglex(x1, y1, x2, y2) result(ax)
-! ******************************************************************************
-! anglex -- Calculate the angle that the x-axis makes with a line that is
-!   normal to the two points.  This assumes that vertices are numbered
-!   clockwise so that the angle is for the normal outward of cell n.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use ConstantsModule, only: DZERO, DTWO, DPI
+    ! -- dummy
     real(DP), intent(in) :: x1
     real(DP), intent(in) :: x2
     real(DP), intent(in) :: y1
     real(DP), intent(in) :: y2
+    ! -- return
     real(DP) :: ax
+    ! -- local
     real(DP) :: dx
     real(DP) :: dy
-! ------------------------------------------------------------------------------
+    !
     dx = x2 - x1
     dy = y2 - y1
     ax = atan2(dx, -dy)
     if (ax < DZERO) ax = DTWO * DPI + ax
+    !
+    ! -- Return
     return
   end function anglex
 
+  !> @brief Calculate distance between two points
+  !<
   function distance(x1, y1, x2, y2) result(d)
-! ******************************************************************************
-! distance -- Calculate distance between two points
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     real(DP), intent(in) :: x1
     real(DP), intent(in) :: x2
     real(DP), intent(in) :: y1
     real(DP), intent(in) :: y2
+    ! -- return
     real(DP) :: d
-! ------------------------------------------------------------------------------
+    !
     d = (x1 - x2)**2 + (y1 - y2)**2
     d = sqrt(d)
+    !
+    ! -- Return
     return
   end function distance
 
+  !> @brief Calculate normal distance from point (x0, y0) to line defined by
+  !! two points, (x1, y1), (x2, y2).
+  !<
   function distance_normal(x0, y0, x1, y1, x2, y2) result(d)
-! ******************************************************************************
-! distance_normal -- Calculate normal distance from point (x0, y0) to line
-!   defined by two points, (x1, y1), (x2, y2)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     real(DP), intent(in) :: x0
     real(DP), intent(in) :: y0
     real(DP), intent(in) :: x1
     real(DP), intent(in) :: y1
     real(DP), intent(in) :: x2
     real(DP), intent(in) :: y2
+    ! -- return
     real(DP) :: d
-! ------------------------------------------------------------------------------
+    !
     d = abs((x2 - x1) * (y1 - y0) - (x1 - x0) * (y2 - y1))
     d = d / distance(x1, y1, x2, y2)
+    !
+    ! -- Return
     return
   end function distance_normal
 
+  !> @brief Calculate the normal vector components (xcomp and ycomp) for a line
+  !! defined by two points, (x0, y0), (x1, y1).
+  !<
   subroutine line_unit_normal(x0, y0, x1, y1, xcomp, ycomp)
-! ******************************************************************************
-! line_unit_normal -- Calculate the normal vector components (xcomp and ycomp)
-!   for a line defined by two points, (x0, y0), (x1, y1)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     real(DP), intent(in) :: x0
     real(DP), intent(in) :: y0
     real(DP), intent(in) :: x1
     real(DP), intent(in) :: y1
     real(DP), intent(out) :: xcomp
     real(DP), intent(out) :: ycomp
+    ! -- local
     real(DP) :: dx, dy, vmag
-! ------------------------------------------------------------------------------
+    !
     dx = x1 - x0
     dy = y1 - y0
     vmag = sqrt(dx**2 + dy**2)
     xcomp = -dy / vmag
     ycomp = dx / vmag
+    !
+    ! -- Return
     return
   end subroutine line_unit_normal
 
+  !> @brief Calculate the vector components (xcomp, ycomp, and zcomp) for a
+  !! line defined by two points, (x0, y0, z0), (x1, y1, z1).
+  !!
+  !! Also return the magnitude of the original vector, vmag.
+  !<
   subroutine line_unit_vector(x0, y0, z0, x1, y1, z1, &
                               xcomp, ycomp, zcomp, vmag)
-! ******************************************************************************
-! line_unit_vector -- Calculate the vector components (xcomp, ycomp, and zcomp)
-!   for a line defined by two points, (x0, y0, z0), (x1, y1, z1). Also return
-!   the magnitude of the original vector, vmag.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     real(DP), intent(in) :: x0
     real(DP), intent(in) :: y0
     real(DP), intent(in) :: z0
@@ -478,8 +515,10 @@ subroutine line_unit_vector(x0, y0, z0, x1, y1, z1, &
     real(DP), intent(out) :: xcomp
     real(DP), intent(out) :: ycomp
     real(DP), intent(out) :: zcomp
-    real(DP) :: dx, dy, dz, vmag
-! ------------------------------------------------------------------------------
+    real(DP) :: vmag
+    ! -- local
+    real(DP) :: dx, dy, dz
+    !
     dx = x1 - x0
     dy = y1 - y0
     dz = z1 - z0
@@ -487,6 +526,8 @@ subroutine line_unit_vector(x0, y0, z0, x1, y1, z1, &
     xcomp = dx / vmag
     ycomp = dy / vmag
     zcomp = dz / vmag
+    !
+    ! -- Return
     return
   end subroutine line_unit_vector
 
diff --git a/src/Model/ModelUtilities/FlowModelInterface.f90 b/src/Model/ModelUtilities/FlowModelInterface.f90
new file mode 100644
index 00000000000..73b539a40af
--- /dev/null
+++ b/src/Model/ModelUtilities/FlowModelInterface.f90
@@ -0,0 +1,983 @@
+module FlowModelInterfaceModule
+
+  use KindModule, only: DP, I4B, LGP
+  use ConstantsModule, only: DONE, DZERO, DHALF, LINELENGTH, LENBUDTXT, &
+                             LENPACKAGENAME, LENVARNAME
+  use SimModule, only: store_error, store_error_unit
+  use SimVariablesModule, only: errmsg
+  use NumericalPackageModule, only: NumericalPackageType
+  use BaseDisModule, only: DisBaseType
+  use ListModule, only: ListType
+  use BudgetFileReaderModule, only: BudgetFileReaderType
+  use HeadFileReaderModule, only: HeadFileReaderType
+  use PackageBudgetModule, only: PackageBudgetType
+  use BudgetObjectModule, only: BudgetObjectType, budgetobject_cr_bfr
+
+  implicit none
+  private
+  public :: FlowModelInterfaceType
+
+  type, extends(NumericalPackageType) :: FlowModelInterfaceType
+
+    character(len=LENPACKAGENAME) :: text = '' !< text string for package
+    logical, pointer :: flows_from_file => null() !< if .false., then flows come from GWF through GWF-Model exg
+    type(ListType), pointer :: gwfbndlist => null() !< list of gwf stress packages
+    integer(I4B), pointer :: iflowsupdated => null() !< flows were updated for this time step
+    integer(I4B), dimension(:), pointer, contiguous :: ibound => null() !< pointer to Model ibound
+    real(DP), dimension(:), pointer, contiguous :: gwfflowja => null() !< pointer to the GWF flowja array
+    real(DP), dimension(:, :), pointer, contiguous :: gwfspdis => null() !< pointer to npf specific discharge array
+    real(DP), dimension(:), pointer, contiguous :: gwfhead => null() !< pointer to the GWF head array
+    real(DP), dimension(:), pointer, contiguous :: gwfsat => null() !< pointer to the GWF saturation array
+    integer(I4B), dimension(:), pointer, contiguous :: ibdgwfsat0 => null() !< mark cells with saturation = 0 to exclude from dispersion
+    real(DP), dimension(:), pointer, contiguous :: gwfstrgss => null() !< pointer to flow model QSTOSS
+    real(DP), dimension(:), pointer, contiguous :: gwfstrgsy => null() !< pointer to flow model QSTOSY
+    integer(I4B), pointer :: igwfstrgss => null() !< indicates if gwfstrgss is available
+    integer(I4B), pointer :: igwfstrgsy => null() !< indicates if gwfstrgsy is available
+    integer(I4B), pointer :: iubud => null() !< unit number GWF budget file
+    integer(I4B), pointer :: iuhds => null() !< unit number GWF head file
+    integer(I4B), pointer :: iumvr => null() !< unit number GWF mover budget file
+    integer(I4B), pointer :: nflowpack => null() !< number of GWF flow packages
+    integer(I4B), dimension(:), pointer, contiguous :: igwfmvrterm => null() !< flag to indicate that gwf package is a mover term
+    type(BudgetFileReaderType) :: bfr !< budget file reader
+    type(HeadFileReaderType) :: hfr !< head file reader
+    type(PackageBudgetType), dimension(:), allocatable :: gwfpackages !< used to get flows between a package and gwf
+    type(BudgetObjectType), pointer :: mvrbudobj => null() !< pointer to the mover budget budget object
+    character(len=16), dimension(:), allocatable :: flowpacknamearray !< array of boundary package names (e.g. LAK-1, SFR-3, etc.)
+    character(len=LENVARNAME) :: depvartype = ''
+
+  contains
+
+    procedure :: advance_bfr
+    procedure :: advance_hfr
+    procedure :: allocate_arrays
+    procedure :: allocate_gwfpackages
+    procedure :: allocate_scalars
+    procedure :: deallocate_gwfpackages
+    procedure :: finalize_bfr
+    procedure :: finalize_hfr
+    procedure :: fmi_ar
+    procedure :: fmi_da
+    procedure :: fmi_df
+    procedure :: get_package_index
+    procedure :: initialize_bfr
+    procedure :: initialize_gwfterms_from_bfr
+    procedure :: initialize_gwfterms_from_gwfbndlist
+    procedure :: initialize_hfr
+    procedure :: read_options
+    procedure :: read_packagedata
+
+  end type FlowModelInterfaceType
+
+contains
+
+  !> @brief Define the flow model interface
+  !<
+  subroutine fmi_df(this, dis)
+    ! -- modules
+    use SimModule, only: store_error
+    ! -- dummy
+    class(FlowModelInterfaceType) :: this
+    class(DisBaseType), pointer, intent(in) :: dis
+    ! -- formats
+    character(len=*), parameter :: fmtfmi = &
+      "(1x,/1x,'FMI -- FLOW MODEL INTERFACE, VERSION 2, 8/17/2023',            &
+      &' INPUT READ FROM UNIT ', i0, //)"
+    character(len=*), parameter :: fmtfmi0 = &
+                    "(1x,/1x,'FMI -- FLOW MODEL INTERFACE,'&
+                    &' VERSION 2, 8/17/2023')"
+
+    ! --print a message identifying the FMI package.
+    if (this%iout > 0) then
+      if (this%inunit /= 0) then
+        write (this%iout, fmtfmi) this%inunit
+      else
+        write (this%iout, fmtfmi0)
+        if (this%flows_from_file) then
+          write (this%iout, '(a)') '  FLOWS ARE ASSUMED TO BE ZERO.'
+        else
+          write (this%iout, '(a)') '  FLOWS PROVIDED BY A GWF MODEL IN THIS &
+            &SIMULATION'
+        end if
+      end if
+    end if
+    !
+    ! -- Store pointers
+    this%dis => dis
+    !
+    ! -- Read fmi options
+    if (this%inunit /= 0) then
+      call this%read_options()
+    end if
+    !
+    ! -- Read packagedata options
+    if (this%inunit /= 0 .and. this%flows_from_file) then
+      call this%read_packagedata()
+      call this%initialize_gwfterms_from_bfr()
+    end if
+    !
+    ! -- If GWF-Model exchange is active, setup flow terms
+    if (.not. this%flows_from_file) then
+      call this%initialize_gwfterms_from_gwfbndlist()
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine fmi_df
+
+  !> @brief Allocate the package
+  !<
+  subroutine fmi_ar(this, ibound)
+    ! -- modules
+    use SimModule, only: store_error
+    ! -- dummy
+    class(FlowModelInterfaceType) :: this
+    integer(I4B), dimension(:), pointer, contiguous :: ibound
+    !
+    ! -- store pointers to arguments that were passed in
+    this%ibound => ibound
+    !
+    ! -- Allocate arrays
+    call this%allocate_arrays(this%dis%nodes)
+    !
+    ! -- Return
+    return
+  end subroutine fmi_ar
+
+  !> @brief Deallocate variables
+  !<
+  subroutine fmi_da(this)
+    ! -- modules
+    use MemoryManagerModule, only: mem_deallocate
+    ! -- dummy
+    class(FlowModelInterfaceType) :: this
+    ! -- todo: finalize hfr and bfr either here or in a finalize routine
+    !
+    ! -- deallocate any memory stored with gwfpackages
+    call this%deallocate_gwfpackages()
+    !
+    ! -- deallocate fmi arrays
+    deallocate (this%gwfpackages)
+    deallocate (this%flowpacknamearray)
+    call mem_deallocate(this%igwfmvrterm)
+    call mem_deallocate(this%ibdgwfsat0)
+    !
+    if (this%flows_from_file) then
+      call mem_deallocate(this%gwfstrgss)
+      call mem_deallocate(this%gwfstrgsy)
+    end if
+    !
+    ! -- special treatment, these could be from mem_checkin
+    call mem_deallocate(this%gwfhead, 'GWFHEAD', this%memoryPath)
+    call mem_deallocate(this%gwfsat, 'GWFSAT', this%memoryPath)
+    call mem_deallocate(this%gwfspdis, 'GWFSPDIS', this%memoryPath)
+    call mem_deallocate(this%gwfflowja, 'GWFFLOWJA', this%memoryPath)
+    !
+    ! -- deallocate scalars
+    call mem_deallocate(this%flows_from_file)
+    call mem_deallocate(this%iflowsupdated)
+    call mem_deallocate(this%igwfstrgss)
+    call mem_deallocate(this%igwfstrgsy)
+    call mem_deallocate(this%iubud)
+    call mem_deallocate(this%iuhds)
+    call mem_deallocate(this%iumvr)
+    call mem_deallocate(this%nflowpack)
+    !
+    ! -- deallocate parent
+    call this%NumericalPackageType%da()
+    !
+    ! -- Return
+    return
+  end subroutine fmi_da
+
+  !> @brief Allocate scalars
+  !<
+  subroutine allocate_scalars(this)
+    ! -- modules
+    use MemoryManagerModule, only: mem_allocate, mem_setptr
+    ! -- dummy
+    class(FlowModelInterfaceType) :: this
+    ! -- local
+    !
+    ! -- allocate scalars in NumericalPackageType
+    call this%NumericalPackageType%allocate_scalars()
+    !
+    ! -- Allocate
+    call mem_allocate(this%flows_from_file, 'FLOWS_FROM_FILE', this%memoryPath)
+    call mem_allocate(this%iflowsupdated, 'IFLOWSUPDATED', this%memoryPath)
+    call mem_allocate(this%igwfstrgss, 'IGWFSTRGSS', this%memoryPath)
+    call mem_allocate(this%igwfstrgsy, 'IGWFSTRGSY', this%memoryPath)
+    call mem_allocate(this%iubud, 'IUBUD', this%memoryPath)
+    call mem_allocate(this%iuhds, 'IUHDS', this%memoryPath)
+    call mem_allocate(this%iumvr, 'IUMVR', this%memoryPath)
+    call mem_allocate(this%nflowpack, 'NFLOWPACK', this%memoryPath)
+    !
+    ! !
+    ! -- Initialize
+    this%flows_from_file = .true.
+    this%iflowsupdated = 1
+    this%igwfstrgss = 0
+    this%igwfstrgsy = 0
+    this%iubud = 0
+    this%iuhds = 0
+    this%iumvr = 0
+    this%nflowpack = 0
+    !
+    ! -- Return
+    return
+  end subroutine allocate_scalars
+
+  !> @brief Allocate arrays
+  !<
+  subroutine allocate_arrays(this, nodes)
+    use MemoryManagerModule, only: mem_allocate
+    !modules
+    use ConstantsModule, only: DZERO
+    ! -- dummy
+    class(FlowModelInterfaceType) :: this
+    integer(I4B), intent(in) :: nodes
+    ! -- local
+    integer(I4B) :: n
+    !
+    ! -- Allocate ibdgwfsat0, which is an indicator array marking cells with
+    !    saturation greater than 0.0 with a value of 1
+    call mem_allocate(this%ibdgwfsat0, nodes, 'IBDGWFSAT0', this%memoryPath)
+    do n = 1, nodes
+      this%ibdgwfsat0(n) = 1
+    end do
+    !
+    ! -- Allocate differently depending on whether or not flows are
+    !    being read from a file.
+    if (this%flows_from_file) then
+      call mem_allocate(this%gwfflowja, this%dis%con%nja, &
+                        'GWFFLOWJA', this%memoryPath)
+      call mem_allocate(this%gwfsat, nodes, 'GWFSAT', this%memoryPath)
+      call mem_allocate(this%gwfhead, nodes, 'GWFHEAD', this%memoryPath)
+      call mem_allocate(this%gwfspdis, 3, nodes, 'GWFSPDIS', this%memoryPath)
+      do n = 1, nodes
+        this%gwfsat(n) = DONE
+        this%gwfhead(n) = DZERO
+        this%gwfspdis(:, n) = DZERO
+      end do
+      do n = 1, size(this%gwfflowja)
+        this%gwfflowja(n) = DZERO
+      end do
+      !
+      ! -- allocate and initialize storage arrays
+      if (this%igwfstrgss == 0) then
+        call mem_allocate(this%gwfstrgss, 1, 'GWFSTRGSS', this%memoryPath)
+      else
+        call mem_allocate(this%gwfstrgss, nodes, 'GWFSTRGSS', this%memoryPath)
+      end if
+      if (this%igwfstrgsy == 0) then
+        call mem_allocate(this%gwfstrgsy, 1, 'GWFSTRGSY', this%memoryPath)
+      else
+        call mem_allocate(this%gwfstrgsy, nodes, 'GWFSTRGSY', this%memoryPath)
+      end if
+      do n = 1, size(this%gwfstrgss)
+        this%gwfstrgss(n) = DZERO
+      end do
+      do n = 1, size(this%gwfstrgsy)
+        this%gwfstrgsy(n) = DZERO
+      end do
+      !
+      ! -- If there is no fmi package, then there are no flows at all or a
+      !    connected GWF model, so allocate gwfpackages to zero
+      if (this%inunit == 0) call this%allocate_gwfpackages(this%nflowpack)
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine allocate_arrays
+
+  !> @brief Read options from input file
+  !<
+  subroutine read_options(this)
+    ! -- modules
+    use ConstantsModule, only: LINELENGTH, DEM6
+    use InputOutputModule, only: getunit, openfile, urdaux
+    use SimModule, only: store_error, store_error_unit
+    ! -- dummy
+    class(FlowModelInterfaceType) :: this
+    ! -- local
+    character(len=LINELENGTH) :: keyword
+    integer(I4B) :: ierr
+    logical :: isfound, endOfBlock
+    !
+    ! -- get options block
+    call this%parser%GetBlock('OPTIONS', isfound, ierr, blockRequired=.false., &
+                              supportOpenClose=.true.)
+    !
+    ! -- parse options block if detected
+    if (isfound) then
+      write (this%iout, '(1x,a)') 'PROCESSING FMI OPTIONS'
+      do
+        call this%parser%GetNextLine(endOfBlock)
+        if (endOfBlock) exit
+        call this%parser%GetStringCaps(keyword)
+        select case (keyword)
+        case ('SAVE_FLOWS')
+          this%ipakcb = -1
+        case default
+          write (errmsg, '(a,3(1x,a))') &
+            'UNKNOWN', trim(adjustl(this%text)), 'OPTION:', trim(keyword)
+          call store_error(errmsg)
+          call this%parser%StoreErrorUnit()
+        end select
+      end do
+      write (this%iout, '(1x,a)') 'END OF FMI OPTIONS'
+    end if
+    !
+    ! -- return
+    return
+  end subroutine read_options
+
+  !> @brief Read packagedata block from input file
+  !<
+  subroutine read_packagedata(this)
+    ! -- modules
+    use OpenSpecModule, only: ACCESS, FORM
+    use ConstantsModule, only: LINELENGTH, DEM6, LENPACKAGENAME
+    use InputOutputModule, only: getunit, openfile, urdaux
+    use SimModule, only: store_error, store_error_unit
+    ! -- dummy
+    class(FlowModelInterfaceType) :: this
+    ! -- local
+    character(len=LINELENGTH) :: keyword, fname
+    integer(I4B) :: ierr
+    integer(I4B) :: inunit
+    integer(I4B) :: iapt
+    logical :: isfound, endOfBlock
+    logical :: blockrequired
+    logical :: exist
+    !
+    ! -- initialize
+    iapt = 0
+    blockrequired = .true.
+    !
+    ! -- get options block
+    call this%parser%GetBlock('PACKAGEDATA', isfound, ierr, &
+                              blockRequired=blockRequired, &
+                              supportOpenClose=.true.)
+    !
+    ! -- parse options block if detected
+    if (isfound) then
+      write (this%iout, '(1x,a)') 'PROCESSING FMI PACKAGEDATA'
+      do
+        call this%parser%GetNextLine(endOfBlock)
+        if (endOfBlock) exit
+        call this%parser%GetStringCaps(keyword)
+        select case (keyword)
+        case ('GWFBUDGET')
+          call this%parser%GetStringCaps(keyword)
+          if (keyword /= 'FILEIN') then
+            call store_error('GWFBUDGET KEYWORD MUST BE FOLLOWED BY '// &
+                             '"FILEIN" then by filename.')
+            call this%parser%StoreErrorUnit()
+          end if
+          call this%parser%GetString(fname)
+          inunit = getunit()
+          inquire (file=trim(fname), exist=exist)
+          if (.not. exist) then
+            call store_error('Could not find file '//trim(fname))
+            call this%parser%StoreErrorUnit()
+          end if
+          call openfile(inunit, this%iout, fname, 'DATA(BINARY)', FORM, &
+                        ACCESS, 'UNKNOWN')
+          this%iubud = inunit
+          call this%initialize_bfr()
+        case ('GWFHEAD')
+          call this%parser%GetStringCaps(keyword)
+          if (keyword /= 'FILEIN') then
+            call store_error('GWFHEAD KEYWORD MUST BE FOLLOWED BY '// &
+                             '"FILEIN" then by filename.')
+            call this%parser%StoreErrorUnit()
+          end if
+          call this%parser%GetString(fname)
+          inquire (file=trim(fname), exist=exist)
+          if (.not. exist) then
+            call store_error('Could not find file '//trim(fname))
+            call this%parser%StoreErrorUnit()
+          end if
+          inunit = getunit()
+          call openfile(inunit, this%iout, fname, 'DATA(BINARY)', FORM, &
+                        ACCESS, 'UNKNOWN')
+          this%iuhds = inunit
+          call this%initialize_hfr()
+        case ('GWFMOVER')
+          call this%parser%GetStringCaps(keyword)
+          if (keyword /= 'FILEIN') then
+            call store_error('GWFMOVER KEYWORD MUST BE FOLLOWED BY '// &
+                             '"FILEIN" then by filename.')
+            call this%parser%StoreErrorUnit()
+          end if
+          call this%parser%GetString(fname)
+          inunit = getunit()
+          call openfile(inunit, this%iout, fname, 'DATA(BINARY)', FORM, &
+                        ACCESS, 'UNKNOWN')
+          this%iumvr = inunit
+          call budgetobject_cr_bfr(this%mvrbudobj, 'MVT', this%iumvr, & ! kluge note: MVT?
+                                   this%iout)
+          call this%mvrbudobj%fill_from_bfr(this%dis, this%iout)
+        case default
+          write (errmsg, '(a,3(1x,a))') &
+            'UNKNOWN', trim(adjustl(this%text)), 'PACKAGEDATA:', trim(keyword)
+          call store_error(errmsg)
+        end select
+      end do
+      write (this%iout, '(1x,a)') 'END OF FMI PACKAGEDATA'
+    end if
+    !
+    ! -- return
+    return
+  end subroutine read_packagedata
+
+  !> @brief Initialize the budget file reader
+  !<
+  subroutine initialize_bfr(this)
+    ! -- modules
+    class(FlowModelInterfaceType) :: this
+    ! -- dummy
+    integer(I4B) :: ncrbud
+    !
+    ! -- Initialize the budget file reader
+    call this%bfr%initialize(this%iubud, this%iout, ncrbud)
+    !
+    ! -- todo: need to run through the budget terms
+    !    and do some checking
+  end subroutine initialize_bfr
+
+  !> @brief Advance the budget file reader
+  !!
+  !! Advance the budget file reader by reading the next chunk
+  !! of information for the current time step and stress period.
+  !!
+  !<
+  subroutine advance_bfr(this)
+    ! -- modules
+    use TdisModule, only: kstp, kper
+    ! -- dummy
+    class(FlowModelInterfaceType) :: this
+    ! -- local
+    logical :: success
+    integer(I4B) :: n
+    integer(I4B) :: ipos
+    integer(I4B) :: nu, nr
+    integer(I4B) :: ip, i
+    logical :: readnext
+    ! -- format
+    character(len=*), parameter :: fmtkstpkper = &
+                 "(1x,/1x,'FMI READING BUDGET TERMS &
+                 &FOR KSTP ', i0, ' KPER ', i0)"
+    character(len=*), parameter :: fmtbudkstpkper = &
+      "(1x,/1x, 'FMI SETTING BUDGET TERMS &
+      &FOR KSTP ', i0, ' AND KPER ',        &
+      &i0, ' TO BUDGET FILE TERMS FROM &
+      &KSTP ', i0, ' AND KPER ', i0)"
+    !
+    ! -- If the latest record read from the budget file is from a stress
+    ! -- period with only one time step, reuse that record (do not read a
+    ! -- new record) if the running model is still in that same stress period,
+    ! -- or if that record is the last one in the budget file.
+    readnext = .true.
+    if (kstp * kper > 1) then
+      if (this%bfr%kstp == 1) then
+        if (this%bfr%kpernext == kper + 1) then
+          readnext = .false.
+        else if (this%bfr%endoffile) then
+          readnext = .false.
+        end if
+      else if (this%bfr%endoffile) then
+        write (errmsg, '(4x,a)') 'REACHED END OF GWF BUDGET &
+          &FILE BEFORE READING SUFFICIENT BUDGET INFORMATION FOR THIS &
+          &GWT SIMULATION.'
+        call store_error(errmsg)
+        call store_error_unit(this%iubud)
+      end if
+    end if
+    !
+    ! -- Read the next record
+    if (readnext) then
+      !
+      ! -- Write the current time step and stress period
+      write (this%iout, fmtkstpkper) kstp, kper
+      !
+      ! -- loop through the budget terms for this stress period
+      !    i is the counter for gwf flow packages
+      ip = 1
+      do n = 1, this%bfr%nbudterms
+        call this%bfr%read_record(success, this%iout)
+        if (.not. success) then
+          write (errmsg, '(4x,a)') 'GWF BUDGET READ NOT SUCCESSFUL'
+          call store_error(errmsg)
+          call store_error_unit(this%iubud)
+        end if
+        !
+        ! -- Ensure kper is same between model and budget file
+        if (kper /= this%bfr%kper) then
+          write (errmsg, '(4x,a)') 'PERIOD NUMBER IN BUDGET FILE &
+            &DOES NOT MATCH PERIOD NUMBER IN TRANSPORT MODEL.  IF THERE &
+            &IS MORE THAN ONE TIME STEP IN THE BUDGET FILE FOR A GIVEN &
+            &STRESS PERIOD, BUDGET FILE TIME STEPS MUST MATCH GWT MODEL &
+            &TIME STEPS ONE-FOR-ONE IN THAT STRESS PERIOD.'
+          call store_error(errmsg)
+          call store_error_unit(this%iubud)
+        end if
+        !
+        ! -- if budget file kstp > 1, then kstp must match
+        if (this%bfr%kstp > 1 .and. (kstp /= this%bfr%kstp)) then
+          write (errmsg, '(4x,a)') 'TIME STEP NUMBER IN BUDGET FILE &
+            &DOES NOT MATCH TIME STEP NUMBER IN TRANSPORT MODEL.  IF THERE &
+           &IS MORE THAN ONE TIME STEP IN THE BUDGET FILE FOR A GIVEN STRESS &
+            &PERIOD, BUDGET FILE TIME STEPS MUST MATCH GWT MODEL TIME STEPS &
+            &ONE-FOR-ONE IN THAT STRESS PERIOD.'
+          call store_error(errmsg)
+          call store_error_unit(this%iubud)
+        end if
+        !
+        ! -- parse based on the type of data, and compress all user node
+        !    numbers into reduced node numbers
+        select case (trim(adjustl(this%bfr%budtxt)))
+        case ('FLOW-JA-FACE')
+          !
+          ! -- bfr%flowja contains only reduced connections so there is
+          !    a one-to-one match with this%gwfflowja
+          do ipos = 1, size(this%bfr%flowja)
+            this%gwfflowja(ipos) = this%bfr%flowja(ipos)
+          end do
+        case ('DATA-SPDIS')
+          do i = 1, this%bfr%nlist
+            nu = this%bfr%nodesrc(i)
+            nr = this%dis%get_nodenumber(nu, 0)
+            if (nr <= 0) cycle
+            this%gwfspdis(1, nr) = this%bfr%auxvar(1, i)
+            this%gwfspdis(2, nr) = this%bfr%auxvar(2, i)
+            this%gwfspdis(3, nr) = this%bfr%auxvar(3, i)
+          end do
+        case ('DATA-SAT')
+          do i = 1, this%bfr%nlist
+            nu = this%bfr%nodesrc(i)
+            nr = this%dis%get_nodenumber(nu, 0)
+            if (nr <= 0) cycle
+            this%gwfsat(nr) = this%bfr%auxvar(1, i)
+          end do
+        case ('STO-SS')
+          do nu = 1, this%dis%nodesuser
+            nr = this%dis%get_nodenumber(nu, 0)
+            if (nr <= 0) cycle
+            this%gwfstrgss(nr) = this%bfr%flow(nu)
+          end do
+        case ('STO-SY')
+          do nu = 1, this%dis%nodesuser
+            nr = this%dis%get_nodenumber(nu, 0)
+            if (nr <= 0) cycle
+            this%gwfstrgsy(nr) = this%bfr%flow(nu)
+          end do
+        case default
+          call this%gwfpackages(ip)%copy_values( &
+            this%bfr%nlist, &
+            this%bfr%nodesrc, &
+            this%bfr%flow, &
+            this%bfr%auxvar)
+          do i = 1, this%gwfpackages(ip)%nbound
+            nu = this%gwfpackages(ip)%nodelist(i)
+            nr = this%dis%get_nodenumber(nu, 0)
+            this%gwfpackages(ip)%nodelist(i) = nr
+          end do
+          ip = ip + 1
+        end select
+      end do
+    else
+      !
+      ! -- write message to indicate that flows are being reused
+      write (this%iout, fmtbudkstpkper) kstp, kper, this%bfr%kstp, this%bfr%kper
+      !
+      ! -- set the flag to indicate that flows were not updated
+      this%iflowsupdated = 0
+    end if
+  end subroutine advance_bfr
+
+  !> @brief Finalize the budget file reader
+  !<
+  subroutine finalize_bfr(this)
+    ! -- modules
+    class(FlowModelInterfaceType) :: this
+    ! -- dummy
+    !
+    ! -- Finalize the budget file reader
+    call this%bfr%finalize()
+    !
+  end subroutine finalize_bfr
+
+  !> @brief Initialize the head file reader
+  !<
+  subroutine initialize_hfr(this)
+    ! -- modules
+    class(FlowModelInterfaceType) :: this
+    ! -- dummy
+    !
+    ! -- Initialize the budget file reader
+    call this%hfr%initialize(this%iuhds, this%iout)
+    !
+    ! -- todo: need to run through the head terms
+    !    and do some checking
+  end subroutine initialize_hfr
+
+  !> @brief Advance the head file reader
+  !<
+  subroutine advance_hfr(this)
+    ! -- modules
+    use TdisModule, only: kstp, kper
+    class(FlowModelInterfaceType) :: this
+    integer(I4B) :: nu, nr, i, ilay
+    integer(I4B) :: ncpl
+    real(DP) :: val
+    logical :: readnext
+    logical :: success
+    character(len=*), parameter :: fmtkstpkper = &
+                         "(1x,/1x,'FMI READING HEAD FOR &
+                         &KSTP ', i0, ' KPER ', i0)"
+    character(len=*), parameter :: fmthdskstpkper = &
+      "(1x,/1x, 'FMI SETTING HEAD FOR KSTP ', i0, ' AND KPER ',        &
+      &i0, ' TO BINARY FILE HEADS FROM KSTP ', i0, ' AND KPER ', i0)"
+    !
+    ! -- If the latest record read from the head file is from a stress
+    ! -- period with only one time step, reuse that record (do not read a
+    ! -- new record) if the running model is still in that same stress period,
+    ! -- or if that record is the last one in the head file.
+    readnext = .true.
+    if (kstp * kper > 1) then
+      if (this%hfr%kstp == 1) then
+        if (this%hfr%kpernext == kper + 1) then
+          readnext = .false.
+        else if (this%hfr%endoffile) then
+          readnext = .false.
+        end if
+      else if (this%hfr%endoffile) then
+        write (errmsg, '(4x,a)') 'REACHED END OF GWF HEAD &
+          &FILE BEFORE READING SUFFICIENT HEAD INFORMATION FOR THIS &
+          &GWT SIMULATION.'
+        call store_error(errmsg)
+        call store_error_unit(this%iuhds)
+      end if
+    end if
+    !
+    ! -- Read the next record
+    if (readnext) then
+      !
+      ! -- write to list file that heads are being read
+      write (this%iout, fmtkstpkper) kstp, kper
+      !
+      ! -- loop through the layered heads for this time step
+      do ilay = 1, this%hfr%nlay
+        !
+        ! -- read next head chunk
+        call this%hfr%read_record(success, this%iout)
+        if (.not. success) then
+          write (errmsg, '(4x,a)') 'GWF HEAD READ NOT SUCCESSFUL'
+          call store_error(errmsg)
+          call store_error_unit(this%iuhds)
+        end if
+        !
+        ! -- Ensure kper is same between model and head file
+        if (kper /= this%hfr%kper) then
+          write (errmsg, '(4x,a)') 'PERIOD NUMBER IN HEAD FILE &
+            &DOES NOT MATCH PERIOD NUMBER IN TRANSPORT MODEL.  IF THERE &
+            &IS MORE THAN ONE TIME STEP IN THE HEAD FILE FOR A GIVEN STRESS &
+            &PERIOD, HEAD FILE TIME STEPS MUST MATCH GWT MODEL TIME STEPS &
+            &ONE-FOR-ONE IN THAT STRESS PERIOD.'
+          call store_error(errmsg)
+          call store_error_unit(this%iuhds)
+        end if
+        !
+        ! -- if head file kstp > 1, then kstp must match
+        if (this%hfr%kstp > 1 .and. (kstp /= this%hfr%kstp)) then
+          write (errmsg, '(4x,a)') 'TIME STEP NUMBER IN HEAD FILE &
+            &DOES NOT MATCH TIME STEP NUMBER IN TRANSPORT MODEL.  IF THERE &
+            &IS MORE THAN ONE TIME STEP IN THE HEAD FILE FOR A GIVEN STRESS &
+            &PERIOD, HEAD FILE TIME STEPS MUST MATCH GWT MODEL TIME STEPS &
+            &ONE-FOR-ONE IN THAT STRESS PERIOD.'
+          call store_error(errmsg)
+          call store_error_unit(this%iuhds)
+        end if
+        !
+        ! -- fill the head array for this layer and
+        !    compress into reduced form
+        ncpl = size(this%hfr%head)
+        do i = 1, ncpl
+          nu = (ilay - 1) * ncpl + i
+          nr = this%dis%get_nodenumber(nu, 0)
+          val = this%hfr%head(i)
+          if (nr > 0) this%gwfhead(nr) = val
+        end do
+      end do
+    else
+      write (this%iout, fmthdskstpkper) kstp, kper, this%hfr%kstp, this%hfr%kper
+    end if
+  end subroutine advance_hfr
+
+  !> @brief Finalize the head file reader
+  !<
+  subroutine finalize_hfr(this)
+    ! -- modules
+    class(FlowModelInterfaceType) :: this
+    ! -- dummy
+    !
+    ! -- Finalize the head file reader
+    close (this%iuhds)
+    !
+  end subroutine finalize_hfr
+
+  !> @brief Initialize gwf terms from budget file
+  !!
+  !! initalize terms and figure out how many
+  !! different terms and packages are contained within the file
+  !!
+  !<
+  subroutine initialize_gwfterms_from_bfr(this)
+    ! -- modules
+    use MemoryManagerModule, only: mem_allocate
+    use SimModule, only: store_error, store_error_unit, count_errors
+    ! -- dummy
+    class(FlowModelInterfaceType) :: this
+    ! -- local
+    integer(I4B) :: nflowpack
+    integer(I4B) :: i, ip
+    integer(I4B) :: naux
+    logical :: found_flowja
+    logical :: found_dataspdis
+    logical :: found_datasat
+    logical :: found_stoss
+    logical :: found_stosy
+    integer(I4B), dimension(:), allocatable :: imap
+    !
+    ! -- Calculate the number of gwf flow packages
+    allocate (imap(this%bfr%nbudterms))
+    imap(:) = 0
+    nflowpack = 0
+    found_flowja = .false.
+    found_dataspdis = .false.
+    found_datasat = .false.
+    found_stoss = .false.
+    found_stosy = .false.
+    do i = 1, this%bfr%nbudterms
+      select case (trim(adjustl(this%bfr%budtxtarray(i))))
+      case ('FLOW-JA-FACE')
+        found_flowja = .true.
+      case ('DATA-SPDIS')
+        found_dataspdis = .true.
+      case ('DATA-SAT')
+        found_datasat = .true.
+      case ('STO-SS')
+        found_stoss = .true.
+        this%igwfstrgss = 1
+      case ('STO-SY')
+        found_stosy = .true.
+        this%igwfstrgsy = 1
+      case default
+        nflowpack = nflowpack + 1
+        imap(i) = 1
+      end select
+    end do
+    !
+    ! -- allocate gwfpackage arrays
+    call this%allocate_gwfpackages(nflowpack)
+    !
+    ! -- Copy the package name and aux names from budget file reader
+    !    to the gwfpackages derived-type variable
+    ip = 1
+    do i = 1, this%bfr%nbudterms
+      if (imap(i) == 0) cycle
+      call this%gwfpackages(ip)%set_name(this%bfr%dstpackagenamearray(i), &
+                                         this%bfr%budtxtarray(i))
+      naux = this%bfr%nauxarray(i)
+      call this%gwfpackages(ip)%set_auxname(naux, this%bfr%auxtxtarray(1:naux, i))
+      ip = ip + 1
+    end do
+    !
+    ! -- Copy just the package names for the boundary packages into
+    !    the flowpacknamearray
+    ip = 1
+    do i = 1, size(imap)
+      if (imap(i) == 1) then
+        this%flowpacknamearray(ip) = this%bfr%dstpackagenamearray(i)
+        ip = ip + 1
+      end if
+    end do
+    !
+    ! -- Error if specific discharge, saturation or flowja not found
+    if (.not. found_dataspdis) then
+      write (errmsg, '(4x,a)') 'SPECIFIC DISCHARGE NOT FOUND IN &
+                              &BUDGET FILE. SAVE_SPECIFIC_DISCHARGE AND &
+                              &SAVE_FLOWS MUST BE ACTIVATED IN THE NPF PACKAGE.'
+      call store_error(errmsg)
+    end if
+    if (.not. found_datasat) then
+      write (errmsg, '(4x,a)') 'SATURATION NOT FOUND IN &
+                              &BUDGET FILE. SAVE_SATURATION AND &
+                              &SAVE_FLOWS MUST BE ACTIVATED IN THE NPF PACKAGE.'
+      call store_error(errmsg)
+    end if
+    if (.not. found_flowja) then
+      write (errmsg, '(4x,a)') 'FLOWJA NOT FOUND IN &
+                              &BUDGET FILE. SAVE_FLOWS MUST &
+                              &BE ACTIVATED IN THE NPF PACKAGE.'
+      call store_error(errmsg)
+    end if
+    if (count_errors() > 0) then
+      call this%parser%StoreErrorUnit()
+    end if
+    !
+    ! -- return
+    return
+  end subroutine initialize_gwfterms_from_bfr
+
+  !> @brief Initialize gwf terms from a GWF exchange
+  !<
+  subroutine initialize_gwfterms_from_gwfbndlist(this)
+    ! -- modules
+    use BndModule, only: BndType, GetBndFromList
+    ! -- dummy
+    class(FlowModelInterfaceType) :: this
+    ! -- local
+    integer(I4B) :: ngwfpack
+    integer(I4B) :: ngwfterms
+    integer(I4B) :: ip
+    integer(I4B) :: imover
+    integer(I4B) :: ntomvr
+    integer(I4B) :: iterm
+    character(len=LENPACKAGENAME) :: budtxt
+    class(BndType), pointer :: packobj => null()
+    !
+    ! -- determine size of gwf terms
+    ngwfpack = this%gwfbndlist%Count()
+    !
+    ! -- Count number of to-mvr terms, but do not include advanced packages
+    !    as those mover terms are not losses from the cell, but rather flows
+    !    within the advanced package
+    ntomvr = 0
+    do ip = 1, ngwfpack
+      packobj => GetBndFromList(this%gwfbndlist, ip)
+      imover = packobj%imover
+      if (packobj%isadvpak /= 0) imover = 0
+      if (imover /= 0) then
+        ntomvr = ntomvr + 1
+      end if
+    end do
+    !
+    ! -- Allocate arrays in fmi of size ngwfterms, which is the number of
+    !    packages plus the number of packages with mover terms.
+    ngwfterms = ngwfpack + ntomvr
+    call this%allocate_gwfpackages(ngwfterms)
+    !
+    ! -- Assign values in the fmi package
+    iterm = 1
+    do ip = 1, ngwfpack
+      !
+      ! -- set and store names
+      packobj => GetBndFromList(this%gwfbndlist, ip)
+      budtxt = adjustl(packobj%text)
+      call this%gwfpackages(iterm)%set_name(packobj%packName, budtxt)
+      this%flowpacknamearray(iterm) = packobj%packName
+      iterm = iterm + 1
+      !
+      ! -- if this package has a mover associated with it, then add another
+      !    term that corresponds to the mover flows
+      imover = packobj%imover
+      if (packobj%isadvpak /= 0) imover = 0
+      if (imover /= 0) then
+        budtxt = trim(adjustl(packobj%text))//'-TO-MVR'
+        call this%gwfpackages(iterm)%set_name(packobj%packName, budtxt)
+        this%flowpacknamearray(iterm) = packobj%packName
+        this%igwfmvrterm(iterm) = 1
+        iterm = iterm + 1
+      end if
+    end do
+    return
+  end subroutine initialize_gwfterms_from_gwfbndlist
+
+  !> @brief Allocate budget packages
+  !!
+  !! gwfpackages is an array of PackageBudget objects.
+  !! This routine allocates gwfpackages to the proper size and initializes some
+  !! member variables.
+  !<
+  subroutine allocate_gwfpackages(this, ngwfterms)
+    ! -- modules
+    use ConstantsModule, only: LENMEMPATH
+    use MemoryManagerModule, only: mem_allocate
+    ! -- dummy
+    class(FlowModelInterfaceType) :: this
+    integer(I4B), intent(in) :: ngwfterms
+    ! -- local
+    integer(I4B) :: n
+    character(len=LENMEMPATH) :: memPath
+    !
+    ! -- direct allocate
+    allocate (this%gwfpackages(ngwfterms))
+    allocate (this%flowpacknamearray(ngwfterms))
+    !
+    ! -- mem_allocate
+    call mem_allocate(this%igwfmvrterm, ngwfterms, 'IGWFMVRTERM', this%memoryPath)
+    !
+    ! -- initialize
+    this%nflowpack = ngwfterms
+    do n = 1, this%nflowpack
+      this%igwfmvrterm(n) = 0
+      this%flowpacknamearray(n) = ''
+      !
+      ! -- Create a mempath for each individual flow package data set
+      !    of the form, MODELNAME/FMI-FTn
+      write (memPath, '(a, i0)') trim(this%memoryPath)//'-FT', n
+      call this%gwfpackages(n)%initialize(memPath)
+    end do
+    !
+    ! -- return
+    return
+  end subroutine allocate_gwfpackages
+
+  !> @brief Deallocate memory in the gwfpackages array
+  !<
+  subroutine deallocate_gwfpackages(this)
+    ! -- modules
+    ! -- dummy
+    class(FlowModelInterfaceType) :: this
+    ! -- local
+    integer(I4B) :: n
+    !
+    ! -- initialize
+    do n = 1, this%nflowpack
+      call this%gwfpackages(n)%da()
+    end do
+    !
+    ! -- return
+    return
+  end subroutine deallocate_gwfpackages
+
+  !> @brief Find the package index for the package with the given name
+  !<
+  subroutine get_package_index(this, name, idx)
+    use BndModule, only: BndType, GetBndFromList
+    class(FlowModelInterfaceType) :: this
+    character(len=*), intent(in) :: name
+    integer(I4B), intent(inout) :: idx
+    ! -- local
+    integer(I4B) :: ip
+    !
+    ! -- Look through all the packages and return the index with name
+    idx = 0
+    do ip = 1, size(this%flowpacknamearray)
+      if (this%flowpacknamearray(ip) == name) then
+        idx = ip
+        exit
+      end if
+    end do
+    if (idx == 0) then
+      call store_error('Error in get_package_index.  Could not find '//name, &
+                       terminate=.TRUE.)
+    end if
+    !
+    ! -- return
+    return
+  end subroutine get_package_index
+
+end module FlowModelInterfaceModule
diff --git a/src/Model/ModelUtilities/GwtSpc.f90 b/src/Model/ModelUtilities/GwtSpc.f90
index 9b33f196e2d..0b0677afc91 100644
--- a/src/Model/ModelUtilities/GwtSpc.f90
+++ b/src/Model/ModelUtilities/GwtSpc.f90
@@ -117,7 +117,7 @@ subroutine initialize(this, dis, id, inunit, iout, name_model, packNameFlow)
     !
     ! -- Setup the time series manager
     call tsmanager_cr(this%TsManager, this%iout)
-    call tasmanager_cr(this%TasManager, dis, this%iout)
+    call tasmanager_cr(this%TasManager, dis, name_model, this%iout)
     !
     ! -- read options
     call this%read_options()
diff --git a/src/Model/ModelUtilities/ModelPackageInput.f90 b/src/Model/ModelUtilities/ModelPackageInput.f90
new file mode 100644
index 00000000000..09782fd08d8
--- /dev/null
+++ b/src/Model/ModelUtilities/ModelPackageInput.f90
@@ -0,0 +1,99 @@
+!> @brief This module contains the ModelPackageInputModule
+!!
+!! Add an input model type to routines in this module
+!! to integrate the Model with IDM.
+!!
+!<
+module ModelPackageInputModule
+
+  use KindModule, only: DP, I4B, LGP
+  use SimVariablesModule, only: errmsg
+  use ConstantsModule, only: LENFTYPE, LENPACKAGETYPE
+  use SimModule, only: store_error, store_error_filename
+  use GwfModule, only: GWF_NBASEPKG, GWF_NMULTIPKG, &
+                       GWF_BASEPKG, GWF_MULTIPKG
+  use GwtModule, only: GWT_NBASEPKG, GWT_NMULTIPKG, &
+                       GWT_BASEPKG, GWT_MULTIPKG
+
+  implicit none
+  private
+  public :: supported_model_packages
+  public :: multi_package_type
+
+contains
+
+  !> @brief set supported package types for model
+  !!
+  !! Allocate a list of package types supported
+  !! by the model.  Base packages should be listed
+  !! first as list determines load order.
+  !!
+  !<
+  subroutine supported_model_packages(mtype, pkgtypes, numpkgs)
+    ! -- modules
+    ! -- dummy
+    character(len=LENFTYPE), intent(in) :: mtype
+    character(len=LENPACKAGETYPE), dimension(:), allocatable, &
+      intent(inout) :: pkgtypes
+    integer(I4B), intent(inout) :: numpkgs
+    ! -- local
+    !
+    select case (mtype)
+    case ('GWF6')
+      numpkgs = GWF_NBASEPKG + GWF_NMULTIPKG
+      allocate (pkgtypes(numpkgs))
+      pkgtypes = [GWF_BASEPKG, GWF_MULTIPKG]
+      !
+    case ('GWT6')
+      numpkgs = GWT_NBASEPKG + GWT_NMULTIPKG
+      allocate (pkgtypes(numpkgs))
+      pkgtypes = [GWT_BASEPKG, GWT_MULTIPKG]
+      !
+    case default
+    end select
+    !
+    ! -- return
+    return
+  end subroutine supported_model_packages
+
+  !> @brief Is the package multi-instance
+  !<
+  function multi_package_type(mtype_component, ptype_component, pkgtype) &
+    result(multi_package)
+    ! -- modules
+    ! -- dummy
+    character(len=LENFTYPE), intent(in) :: mtype_component
+    character(len=LENFTYPE), intent(in) :: ptype_component
+    character(len=LENFTYPE), intent(in) :: pkgtype
+    ! -- return
+    logical(LGP) :: multi_package
+    ! -- local
+    integer(I4B) :: n
+    !
+    multi_package = .false.
+    !
+    select case (mtype_component)
+    case ('GWF')
+      do n = 1, GWF_NMULTIPKG
+        if (GWF_MULTIPKG(n) == pkgtype) then
+          multi_package = .true.
+          exit
+        end if
+      end do
+      !
+    case ('GWT')
+      do n = 1, GWT_NMULTIPKG
+        if (GWT_MULTIPKG(n) == pkgtype) then
+          multi_package = .true.
+          exit
+        end if
+      end do
+      !
+    case default
+    end select
+    !
+    ! -- return
+    return
+  end function multi_package_type
+
+end module ModelPackageInputModule
diff --git a/src/Model/ModelUtilities/Mover.f90 b/src/Model/ModelUtilities/Mover.f90
index 64d52ce1a8c..1e560c036ad 100644
--- a/src/Model/ModelUtilities/Mover.f90
+++ b/src/Model/ModelUtilities/Mover.f90
@@ -6,7 +6,7 @@
 !<
 module MvrModule
 
-  use KindModule, only: DP, I4B
+  use KindModule, only: DP, I4B, LGP
   use ConstantsModule, only: LENMODELNAME, LINELENGTH, LENBUDTXT, &
                              LENAUXNAME, LENBOUNDNAME, DZERO, DONE, &
                              LENMEMPATH
@@ -27,12 +27,15 @@ module MvrModule
   !!
   !<
   type MvrType
-    character(len=LENMEMPATH) :: pckNameSrc = '' !< provider package name
-    character(len=LENMEMPATH) :: pckNameTgt = '' !< receiver package name
+    character(len=LENMEMPATH) :: mem_path_src = '' !< provider package name
+    character(len=LENMEMPATH) :: mem_path_tgt = '' !< receiver package name
     integer(I4B), pointer :: iRchNrSrc => null() !< provider reach number
+    integer(I4B) :: iRchNrSrcMapped !< mapped provider reach number (currently for lake outlet)
     integer(I4B), pointer :: iRchNrTgt => null() !< receiver reach number
     integer(I4B), pointer :: imvrtype => null() !< mover type (1, 2, 3, 4) corresponds to mvrtypes
     real(DP), pointer :: value => null() !< factor or rate depending on mvrtype
+    logical(LGP) :: is_provider_active = .true.
+    logical(LGP) :: is_receiver_active = .true.
     real(DP) :: qpactual = DZERO !< rate provided to the receiver
     real(DP) :: qavailable = DZERO !< rate available at time of providing
     real(DP), pointer :: qtformvr_ptr => null() !< pointer to total available flow (qtformvr)
@@ -44,7 +47,8 @@ module MvrModule
     procedure :: prepare
     procedure :: echo
     procedure :: advance
-    procedure :: fc
+    procedure :: update_provider
+    procedure :: update_receiver
     procedure :: qrcalc
     procedure :: writeflow
   end type MvrType
@@ -69,13 +73,16 @@ subroutine set_values(this, mname1, pname1, id1, mname2, pname2, &
     integer(I4B), intent(in), target :: imvrtype
     real(DP), intent(in), target :: value
 
-    this%pckNameSrc = create_mem_path(mname1, pname1)
+    this%mem_path_src = create_mem_path(mname1, pname1)
     this%iRchNrSrc => id1
-    this%pckNameTgt = create_mem_path(mname2, pname2)
+    this%mem_path_tgt = create_mem_path(mname2, pname2)
     this%iRchNrTgt => id2
     this%imvrtype => imvrtype
     this%value => value
 
+    ! to be set later
+    this%iRchNrSrcMapped = -1
+
     return
   end subroutine set_values
 
@@ -102,10 +109,10 @@ subroutine prepare(this, inunit, pckMemPaths, pakmovers)
     integer(I4B) :: ipakloc1, ipakloc2
     !
     ! -- Check to make sure provider and receiver are not the same
-    if (this%pckNameSrc == this%pckNameTgt .and. &
+    if (this%mem_path_src == this%mem_path_tgt .and. &
         this%iRchNrSrc == this%iRchNrTgt) then
       call store_error('Provider and receiver are the same: '// &
-                       trim(this%pckNameSrc)//' : '//trim(this%pckNameTgt))
+                       trim(this%mem_path_src)//' : '//trim(this%mem_path_tgt))
       call store_error_unit(inunit)
     end if
     !
@@ -114,62 +121,68 @@ subroutine prepare(this, inunit, pckMemPaths, pakmovers)
     found = .false.
     ipakloc1 = 0
     do i = 1, size(pckMemPaths)
-      if (this%pckNameSrc == pckMemPaths(i)) then
+      if (this%mem_path_src == pckMemPaths(i)) then
         found = .true.
         ipakloc1 = i
         exit
       end if
     end do
     if (.not. found) then
-      call store_error('Mover capability not activated in '//this%pckNameSrc)
+      call store_error('Mover capability not activated in '//this%mem_path_src)
       call store_error('Add "MOVER" keyword to package options block.')
     end if
     found = .false.
     ipakloc2 = 0
     do i = 1, size(pckMemPaths)
-      if (this%pckNameTgt == pckMemPaths(i)) then
+      if (this%mem_path_tgt == pckMemPaths(i)) then
         found = .true.
         ipakloc2 = i
         exit
       end if
     end do
     if (.not. found) then
-      call store_error('Mover capability not activated in '//this%pckNameTgt)
+      call store_error('Mover capability not activated in '//this%mem_path_tgt)
       call store_error('Add "MOVER" keyword to package options block.')
     end if
     if (count_errors() > 0) then
       call store_error_unit(inunit)
     end if
-    !
-    ! -- Set pointer to QTOMVR array in the provider boundary package
-    temp_ptr => pakmovers(ipakloc1)%qtomvr
-    if (this%iRchNrSrc < 1 .or. this%iRchNrSrc > size(temp_ptr)) then
-      call store_error('Provider ID < 1 or greater than package size ')
-      write (errmsg, '(a,i0,a,i0)') 'Provider ID = ', this%iRchNrSrc, &
-        '; Package size = ', size(temp_ptr)
-      call store_error(trim(errmsg))
-      call store_error_unit(inunit)
+
+    if (this%is_provider_active) then
+      !
+      ! -- Set pointer to QTOMVR array in the provider boundary package
+      temp_ptr => pakmovers(ipakloc1)%qtomvr
+      if (this%iRchNrSrc < 1 .or. this%iRchNrSrc > size(temp_ptr)) then
+        call store_error('Provider ID < 1 or greater than package size ')
+        write (errmsg, '(a,i0,a,i0)') 'Provider ID = ', this%iRchNrSrc, &
+          '; Package size = ', size(temp_ptr)
+        call store_error(trim(errmsg))
+        call store_error_unit(inunit)
+      end if
+      this%qtomvr_ptr => temp_ptr(this%iRchNrSrc)
+      !
+      ! -- Set pointer to QFORMVR array in the provider boundary package
+      temp_ptr => pakmovers(ipakloc1)%qformvr
+      this%qformvr_ptr => temp_ptr(this%iRchNrSrc)
+      !
+      ! -- Set pointer to QTFORMVR array in the provider boundary package
+      temp_ptr => pakmovers(ipakloc1)%qtformvr
+      this%qtformvr_ptr => temp_ptr(this%iRchNrSrc)
     end if
-    this%qtomvr_ptr => temp_ptr(this%iRchNrSrc)
-    !
-    ! -- Set pointer to QFORMVR array in the provider boundary package
-    temp_ptr => pakmovers(ipakloc1)%qformvr
-    this%qformvr_ptr => temp_ptr(this%iRchNrSrc)
-    !
-    ! -- Set pointer to QTFORMVR array in the provider boundary package
-    temp_ptr => pakmovers(ipakloc1)%qtformvr
-    this%qtformvr_ptr => temp_ptr(this%iRchNrSrc)
-    !
-    ! -- Set pointer to QFROMMVR array in the receiver boundary package
-    temp_ptr => pakmovers(ipakloc2)%qfrommvr
-    if (this%iRchNrTgt < 1 .or. this%iRchNrTgt > size(temp_ptr)) then
-      call store_error('Receiver ID < 1 or greater than package size ')
-      write (errmsg, '(a,i0,a,i0)') 'Receiver ID = ', this%iRchNrTgt, &
-        '; package size = ', size(temp_ptr)
-      call store_error(trim(errmsg))
-      call store_error_unit(inunit)
+
+    if (this%is_receiver_active) then
+      !
+      ! -- Set pointer to QFROMMVR array in the receiver boundary package
+      temp_ptr => pakmovers(ipakloc2)%qfrommvr
+      if (this%iRchNrTgt < 1 .or. this%iRchNrTgt > size(temp_ptr)) then
+        call store_error('Receiver ID < 1 or greater than package size ')
+        write (errmsg, '(a,i0,a,i0)') 'Receiver ID = ', this%iRchNrTgt, &
+          '; package size = ', size(temp_ptr)
+        call store_error(trim(errmsg))
+        call store_error_unit(inunit)
+      end if
+      this%qfrommvr_ptr => temp_ptr(this%iRchNrTgt)
     end if
-    this%qfrommvr_ptr => temp_ptr(this%iRchNrTgt)
     !
     ! -- return
     return
@@ -187,9 +200,9 @@ subroutine echo(this, iout)
     integer(I4B), intent(in) :: iout !< unit number for output file
     ! -- local
     !
-    write (iout, '(4x, a, a, a, i0)') 'FROM PACKAGE: ', trim(this%pckNameSrc), &
+    write (iout, '(4x, a, a, a, i0)') 'FROM PACKAGE: ', trim(this%mem_path_src), &
       ' FROM ID: ', this%iRchNrSrc
-    write (iout, '(4x, a, a, a, i0)') 'TO PACKAGE: ', trim(this%pckNameTgt), &
+    write (iout, '(4x, a, a, a, i0)') 'TO PACKAGE: ', trim(this%mem_path_tgt), &
       ' TO ID: ', this%iRchNrTgt
     write (iout, '(4x, a, a, a, 1pg15.6,/)') 'MOVER TYPE: ', &
       trim(mvrtypes(this%imvrtype)), ' ', this%value
@@ -215,10 +228,10 @@ end subroutine advance
 
   !> @ brief Formulate coefficients
   !!
-  !! Make mover calculations.
+  !! Make mover calculations for provider.
   !!
   !<
-  subroutine fc(this)
+  subroutine update_provider(this)
     ! -- modules
     ! -- dummy
     class(MvrType) :: this !< MvrType
@@ -237,10 +250,6 @@ subroutine fc(this)
     ! -- Store qpactual
     this%qpactual = qpactual
     !
-    ! -- Add the calculated qpactual term directly into the receiver package
-    !    qfrommvr array.
-    this%qfrommvr_ptr = this%qfrommvr_ptr + qpactual
-    !
     ! -- Add the calculated qpactual term directly into the provider package
     !    qtomvr array.
     this%qtomvr_ptr = this%qtomvr_ptr + qpactual
@@ -251,7 +260,22 @@ subroutine fc(this)
     !
     ! -- return
     return
-  end subroutine fc
+  end subroutine update_provider
+
+  !> @ brief Formulate coefficients
+  !!
+  !! Make mover calculations for receiver.
+  !!
+  !<
+  subroutine update_receiver(this)
+    class(MvrType) :: this !< MvrType
+    ! -- Add the calculated qpactual term directly into the receiver package
+    !    qfrommvr array.
+    this%qfrommvr_ptr = this%qfrommvr_ptr + this%qpactual
+    !
+    ! -- return
+    return
+  end subroutine update_receiver
 
   !> @ brief Flow to receiver
   !!
@@ -319,8 +343,8 @@ subroutine writeflow(this, iout)
       "(1x, a, ' ID ', i0, ' AVAILABLE ', 1(1pg15.6), &
       &' PROVIDED ', 1(1pg15.6), ' TO ', a, ' ID ', i0)"
     !
-    write (iout, fmt) trim(this%pckNameSrc), this%iRchNrSrc, this%qavailable, &
-      this%qpactual, trim(this%pckNameTgt), this%iRchNrTgt
+    write (iout, fmt) trim(this%mem_path_src), this%iRchNrSrc, this%qavailable, &
+      this%qpactual, trim(this%mem_path_tgt), this%iRchNrTgt
     !
     ! -- return
     return
diff --git a/src/Model/ModelUtilities/PackageMover.f90 b/src/Model/ModelUtilities/PackageMover.f90
index 98dc2a9c625..f8304460c1d 100644
--- a/src/Model/ModelUtilities/PackageMover.f90
+++ b/src/Model/ModelUtilities/PackageMover.f90
@@ -26,7 +26,7 @@ module PackageMoverModule
   contains
     procedure :: ar
     procedure :: ad
-    procedure :: cf
+    procedure :: reset
     procedure :: fc
     procedure :: da
     procedure :: allocate_scalars
@@ -100,7 +100,7 @@ subroutine ad(this)
     return
   end subroutine ad
 
-  subroutine cf(this)
+  subroutine reset(this)
     class(PackageMoverType) :: this
     integer :: i
     !
@@ -116,7 +116,7 @@ subroutine cf(this)
     !
     ! -- return
     return
-  end subroutine cf
+  end subroutine reset
 
   subroutine fc(this)
     class(PackageMoverType) :: this
diff --git a/src/Model/ModelUtilities/GwtAdvOptions.f90 b/src/Model/ModelUtilities/TspAdvOptions.f90
similarity index 53%
rename from src/Model/ModelUtilities/GwtAdvOptions.f90
rename to src/Model/ModelUtilities/TspAdvOptions.f90
index 4e724a745d0..08beb0e0d80 100644
--- a/src/Model/ModelUtilities/GwtAdvOptions.f90
+++ b/src/Model/ModelUtilities/TspAdvOptions.f90
@@ -1,10 +1,10 @@
-module GwtAdvOptionsModule
+module TspAdvOptionsModule
   use KindModule, only: I4B
   implicit none
   private
 
-  type, public :: GwtAdvOptionsType
+  type, public :: TspAdvOptionsType
     integer(I4B) :: iAdvScheme !< the advection scheme: 0 = up, 1 = central, 2 = TVD
-  end type GwtAdvOptionsType
+  end type TspAdvOptionsType
 
-end module GwtAdvOptionsModule
+end module TspAdvOptionsModule
diff --git a/src/Model/ModelUtilities/UzfCellGroup.f90 b/src/Model/ModelUtilities/UzfCellGroup.f90
index 5e8cc879535..91c0221ff4b 100644
--- a/src/Model/ModelUtilities/UzfCellGroup.f90
+++ b/src/Model/ModelUtilities/UzfCellGroup.f90
@@ -12,6 +12,7 @@ module UzfCellGroupModule
   public :: UzfCellGroupType
 
   type :: UzfCellGroupType
+
     integer(I4B) :: imem_manager
     real(DP), pointer, dimension(:), contiguous :: thtr => null()
     real(DP), pointer, dimension(:), contiguous :: thts => null()
@@ -53,7 +54,9 @@ module UzfCellGroupModule
     real(DP), pointer, dimension(:), contiguous :: gwpet => null()
     integer(I4B), pointer, dimension(:), contiguous :: landflag => null()
     integer(I4B), pointer, dimension(:), contiguous :: ivertcon => null()
+
   contains
+
     procedure :: init
     procedure :: setdata
     procedure :: sethead
@@ -86,18 +89,12 @@ module UzfCellGroupModule
     procedure :: get_water_content_at_depth
     procedure :: get_wcnew
   end type UzfCellGroupType
-!
+
 contains
-!
-! ------------------------------------------------------------------------------
 
+  !> @brief Allocate and set uzf object variables
+  !<
   subroutine init(this, ncells, nwav, memory_path)
-! ******************************************************************************
-! init -- allocate and set uzf object variables
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
@@ -107,7 +104,6 @@ subroutine init(this, ncells, nwav, memory_path)
     character(len=*), intent(in), optional :: memory_path
     ! -- local
     integer(I4B) :: icell
-! ------------------------------------------------------------------------------
     !
     ! -- Use mem_allocate if memory path is passed in, otherwise it's a temp object
     if (present(memory_path)) then
@@ -238,23 +234,17 @@ subroutine init(this, ncells, nwav, memory_path)
       this%ivertcon(icell) = 0
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine init
 
+  !> @brief Deallocate uzf object variables
+  !<
   subroutine dealloc(this)
-! ******************************************************************************
-! dealloc -- deallocate uzf object variables
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(UzfCellGroupType) :: this
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- deallocate based on whether or not memory manager was used
     if (this%imem_manager == 0) then
@@ -341,19 +331,14 @@ subroutine dealloc(this)
       call mem_deallocate(this%ivertcon)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine dealloc
 
+  !> @brief Set uzf object material properties
+  !<
   subroutine setdata(this, icell, area, top, bot, surfdep, vks, thtr, thts, &
                      thti, eps, ntrail, landflag, ivertcon)
-! ******************************************************************************
-! setdata -- set uzf object material properties
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell
@@ -369,7 +354,6 @@ subroutine setdata(this, icell, area, top, bot, surfdep, vks, thtr, thts, &
     integer(I4B), intent(in) :: ntrail
     integer(I4B), intent(in) :: landflag
     integer(I4B), intent(in) :: ivertcon
-! ------------------------------------------------------------------------------
     !
     ! -- set the values for uzf cell icell
     this%landflag(icell) = landflag
@@ -396,19 +380,13 @@ subroutine setdata(this, icell, area, top, bot, surfdep, vks, thtr, thts, &
     this%hroot(icell) = DZERO
   end subroutine setdata
 
+  !> @brief Set initial head for uzf object
+  !<
   subroutine sethead(this, icell, hgwf)
-! ******************************************************************************
-! sethead -- set uzf object material properties
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell
     real(DP), intent(in) :: hgwf
-! ------------------------------------------------------------------------------
     !
     ! -- set initial head
     this%watab(icell) = this%celbot(icell)
@@ -416,22 +394,19 @@ subroutine sethead(this, icell, hgwf)
     if (this%watab(icell) > this%celtop(icell)) &
       this%watab(icell) = this%celtop(icell)
     this%watabold(icell) = this%watab(icell)
+    !
+    ! -- Return
+    return
   end subroutine sethead
 
+  !> @brief Set infiltration
+  !<
   subroutine setdatafinf(this, icell, finf)
-! ******************************************************************************
-! setdatafinf -- set infiltration
-!
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell
     real(DP), intent(in) :: finf
-! ------------------------------------------------------------------------------
+    !
     if (this%landflag(icell) == 1) then
       this%sinf(icell) = finf
       this%finf(icell) = finf
@@ -442,39 +417,29 @@ subroutine setdatafinf(this, icell, finf)
     this%finf_rej(icell) = DZERO
     this%surflux(icell) = DZERO
     this%surfluxbelow(icell) = DZERO
+    !
+    ! -- Return
+    return
   end subroutine setdatafinf
 
+  !> @brief Set uzfarea using cellarea and areamult
+  !<
   subroutine setdatauzfarea(this, icell, areamult)
-! ******************************************************************************
-! setdatauzfarea -- set uzfarea using cellarea and areamult
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell
     real(DP), intent(in) :: areamult
-! ------------------------------------------------------------------------------
     !
     ! -- set uzf area
     this%uzfarea(icell) = this%cellarea(icell) * areamult
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine setdatauzfarea
 
-! ------------------------------------------------------------------------------
-!
+  !> @brief Set unsaturated ET-related variables
+  !<
   subroutine setdataet(this, icell, jbelow, pet, extdp)
-! ******************************************************************************
-! setdataet -- set unsat. et variables
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell
@@ -483,7 +448,7 @@ subroutine setdataet(this, icell, jbelow, pet, extdp)
     real(DP), intent(in) :: extdp
     ! -- local
     real(DP) :: thick
-! ------------------------------------------------------------------------------
+    !
     if (this%landflag(icell) == 1) then
       this%pet(icell) = pet
       this%gwpet(icell) = pet
@@ -515,18 +480,13 @@ subroutine setdataet(this, icell, jbelow, pet, extdp)
       this%petmax(jbelow) = this%petmax(icell)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine setdataet
 
+  !> @brief Subtract aet from pet to calculate residual et for gw
+  !<
   subroutine setgwpet(this, icell)
-! ******************************************************************************
-! setgwpet -- subtract aet from pet to calculate residual et for gw
-!
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: delt
     ! -- dummy
@@ -534,7 +494,7 @@ subroutine setgwpet(this, icell)
     integer(I4B), intent(in) :: icell
     ! -- dummy
     real(DP) :: pet
-! ------------------------------------------------------------------------------
+    !
     pet = DZERO
     !
     ! -- reduce pet for gw by uzet
@@ -542,18 +502,13 @@ subroutine setgwpet(this, icell)
     if (pet < DZERO) pet = DZERO
     this%gwpet(icell) = pet
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine setgwpet
 
+  !> @brief Subtract aet from pet to calculate residual et for deeper cells
+  !<
   subroutine setbelowpet(this, icell, jbelow)
-! ******************************************************************************
-! setbelowpet -- subtract aet from pet to calculate residual et
-!                for deeper cells
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: delt
     ! -- dummy
@@ -562,7 +517,7 @@ subroutine setbelowpet(this, icell, jbelow)
     integer(I4B), intent(in) :: jbelow
     ! -- dummy
     real(DP) :: pet
-! ------------------------------------------------------------------------------
+    !
     pet = DZERO
     !
     ! -- transfer unmet pet to lower cell
@@ -574,39 +529,30 @@ subroutine setbelowpet(this, icell, jbelow)
     end if
     this%pet(jbelow) = pet
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine setbelowpet
 
+  !> @brief Set extinction water content
+  !<
   subroutine setdataetwc(this, icell, jbelow, extwc)
-! ******************************************************************************
-! setdataetwc -- set extinction water content
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell
     integer(I4B), intent(in) :: jbelow
     real(DP), intent(in) :: extwc
-! ------------------------------------------------------------------------------
     !
     ! -- set extinction water content
     this%extwc(icell) = extwc
     if (jbelow > 0) this%extwc(jbelow) = extwc
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine setdataetwc
 
+  !> @brief Set variables for head-based unsaturated flow
+  !<
   subroutine setdataetha(this, icell, jbelow, ha, hroot, rootact)
-! ******************************************************************************
-! setdataetha -- set variables for head-based unsat. flow
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell
@@ -614,7 +560,6 @@ subroutine setdataetha(this, icell, jbelow, ha, hroot, rootact)
     real(DP), intent(in) :: ha
     real(DP), intent(in) :: hroot
     real(DP), intent(in) :: rootact
-! ------------------------------------------------------------------------------
     !
     ! -- set variables
     this%ha(icell) = ha
@@ -626,39 +571,30 @@ subroutine setdataetha(this, icell, jbelow, ha, hroot, rootact)
       this%rootact(jbelow) = rootact
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine setdataetha
 
+  !> @brief Set variables to advance to new time step. nothing yet.
+  !<
   subroutine advance(this, icell)
-! ******************************************************************************
-! advance -- set variables to advance to new time step. nothing yet.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell
-! ------------------------------------------------------------------------------
     !
     ! -- set variables
     this%surfseep(icell) = DZERO
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine advance
 
+  !> @brief Formulate the unsaturated flow object, calculate terms for gwf
+  !! equation
+  !<
   subroutine solve(this, thiswork, jbelow, icell, totfluxtot, ietflag, &
                    issflag, iseepflag, hgwf, qfrommvr, ierr, &
                    reset_state, trhs, thcof, deriv, watercontent)
-! ******************************************************************************
-! formulate -- formulate the unsaturated flow object, calculate terms for
-!              gwf equation
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: delt
     ! -- dummy
@@ -690,7 +626,6 @@ subroutine solve(this, thiswork, jbelow, icell, totfluxtot, ietflag, &
     real(DP) :: thcofseep
     real(DP) :: deriv1
     real(DP) :: deriv2
-! ------------------------------------------------------------------------------
     !
     ! -- initialize variables
     totfluxtot = DZERO
@@ -721,7 +656,7 @@ subroutine solve(this, thiswork, jbelow, icell, totfluxtot, ietflag, &
     if (reset_state) then
       call thiswork%wave_shift(this, 1, icell, 0, 1, this%nwavst(icell), 1)
     end if
-
+    !
     if (this%watab(icell) > this%celtop(icell)) &
       this%watab(icell) = this%celtop(icell)
     !
@@ -791,17 +726,13 @@ subroutine solve(this, thiswork, jbelow, icell, totfluxtot, ietflag, &
       call this%wave_shift(thiswork, icell, 1, 0, 1, thiswork%nwavst(1), 1)
     end if
     !
+    ! -- Return
     return
   end subroutine solve
 
+  !> @brief Add recharge or infiltration to cells
+  !<
   subroutine addrech(this, icell, jbelow, hgwf, trhs, thcof, deriv, delt)
-! ******************************************************************************
-! addrech -- add recharge or infiltration to cells
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell
@@ -814,7 +745,6 @@ subroutine addrech(this, icell, jbelow, hgwf, trhs, thcof, deriv, delt)
     ! -- local
     real(DP) :: fcheck
     real(DP) :: x, scale, range
-! ------------------------------------------------------------------------------
     !
     ! -- initialize
     range = DEM5
@@ -838,18 +768,13 @@ subroutine addrech(this, icell, jbelow, hgwf, trhs, thcof, deriv, delt)
     this%totflux(icell) = scale * this%totflux(icell) + fcheck * delt
     trhs = this%uzfarea(icell) * this%totflux(icell) / delt
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine addrech
 
+  !> @brief Reject applied infiltration due to low vks
+  !<
   subroutine rejfinf(this, icell, deriv, hgwf, trhs, thcof, finfact)
-! ******************************************************************************
-! rejfinf -- reject applied infiltration due to low vks
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell
@@ -860,7 +785,7 @@ subroutine rejfinf(this, icell, deriv, hgwf, trhs, thcof, finfact)
     real(DP), intent(in) :: hgwf
     ! -- local
     real(DP) :: x, range, scale, q
-! ------------------------------------------------------------------------------
+    !
     range = this%surfdep(icell)
     q = this%surflux(icell)
     finfact = q
@@ -874,18 +799,13 @@ subroutine rejfinf(this, icell, deriv, hgwf, trhs, thcof, finfact)
       thcof = finfact * this%uzfarea(icell) / range
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine rejfinf
 
+  !> @brief Calculate groudwater discharge to land surface
+  !<
   subroutine gwseep(this, icell, deriv, scale, hgwf, trhs, thcof, seep)
-! ******************************************************************************
-! gwseep -- calc. groudwater discharge to land surface
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell
@@ -897,7 +817,7 @@ subroutine gwseep(this, icell, deriv, scale, hgwf, trhs, thcof, seep)
     real(DP), intent(in) :: hgwf
     ! -- local
     real(DP) :: x, range, y, deriv1, d1, d2, Q
-! ------------------------------------------------------------------------------
+    !
     seep = DZERO
     deriv = DZERO
     deriv1 = DZERO
@@ -922,18 +842,13 @@ subroutine gwseep(this, icell, deriv, scale, hgwf, trhs, thcof, seep)
       thcof = DZERO
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine gwseep
 
+  !> @brief Calculate gwf et using residual uzf pet
+  !<
   subroutine simgwet(this, igwetflag, icell, hgwf, trhs, thcof, det)
-! ******************************************************************************
-! simgwet -- calc. gwf et using residual uzf pet
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: igwetflag
@@ -944,7 +859,6 @@ subroutine simgwet(this, igwetflag, icell, hgwf, trhs, thcof, det)
     real(DP), intent(inout) :: det
     ! -- local
     real(DP) :: s, x, c, b, et
-! ------------------------------------------------------------------------------
     !
     this%gwet(icell) = DZERO
     trhs = DZERO
@@ -962,26 +876,20 @@ subroutine simgwet(this, igwetflag, icell, hgwf, trhs, thcof, det)
     else if (igwetflag == 2) then
       et = etfunc_nlin(s, x, c, det, trhs, thcof, hgwf)
     end if
-!    this%gwet(icell) = et * this%uzfarea(icell)
+    ! this%gwet(icell) = et * this%uzfarea(icell)
     trhs = trhs * this%uzfarea(icell)
     thcof = thcof * this%uzfarea(icell)
     this%gwet(icell) = trhs - (thcof * hgwf)
-    !    write(99,*)'in group', icell, this%gwet(icell)
+    ! write(99,*)'in group', icell, this%gwet(icell)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine simgwet
 
+  !> @brief Calculate gwf et using linear ET function from mf-2005
+  !<
   function etfunc_lin(s, x, c, det, trhs, thcof, hgwf, celtop, celbot)
-! ******************************************************************************
-! etfunc_lin -- calc. gwf et using linear ET function from mf-2005
-!
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    ! -- return
+    ! -- Return
     real(DP) :: etfunc_lin
     ! -- dummy
     real(DP), intent(in) :: s
@@ -997,7 +905,6 @@ function etfunc_lin(s, x, c, det, trhs, thcof, hgwf, celtop, celbot)
     real(DP) :: etgw
     real(DP) :: range
     real(DP) :: depth, scale, thick
-! ------------------------------------------------------------------------------
     !
     ! -- Between ET surface and extinction depth
     if (hgwf > (s - x) .and. hgwf < s) THEN
@@ -1033,18 +940,14 @@ function etfunc_lin(s, x, c, det, trhs, thcof, hgwf, celtop, celbot)
     det = -det * etgw
     etfunc_lin = etgw
     !
-    ! -- return
+    ! -- Return
     return
   end function etfunc_lin
 
+  !> @brief Square-wave ET function with smoothing at extinction depth
+  !<
   function etfunc_nlin(s, x, c, det, trhs, thcof, hgwf)
-! ******************************************************************************
-! etfunc_nlin -- Square-wave ET function with smoothing at extinction depth
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- return
+    ! -- Return
     real(DP) :: etfunc_nlin
     ! -- dummy
     real(DP), intent(in) :: s
@@ -1058,7 +961,7 @@ function etfunc_nlin(s, x, c, det, trhs, thcof, hgwf)
     real(DP) :: etgw
     real(DP) :: range
     real(DP) :: depth, scale
-! ------------------------------------------------------------------------------
+    !
     depth = hgwf - (s - x)
     if (depth < DZERO) depth = DZERO
     etgw = c
@@ -1069,24 +972,19 @@ function etfunc_nlin(s, x, c, det, trhs, thcof, hgwf)
     det = -det * etgw
     etfunc_nlin = etgw
     !
-    ! -- return
+    ! -- Return
     return
   end function etfunc_nlin
 
+  !> @brief Calculate recharge due to a rise in the gwf head
+  !<
   subroutine uz_rise(this, icell, totfluxtot)
-! ******************************************************************************
-! uz_rise -- calculate recharge due to a rise in the gwf head
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell
     real(DP), intent(inout) :: totfluxtot
     ! -- local
     real(DP) :: fm1, fm2, d1
-! ------------------------------------------------------------------------------
     !
     ! -- additional recharge from a rising water table
     if (this%watab(icell) - this%watabold(icell) > DEM30) then
@@ -1097,17 +995,13 @@ subroutine uz_rise(this, icell, totfluxtot)
       totfluxtot = totfluxtot + (fm1 - fm2)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uz_rise
 
+  !> @brief Reset waves to default values at start of simulation
+  !<
   subroutine setwaves(this, icell)
-! ******************************************************************************
-! setwaves -- reset waves to default values at start of simulation
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(UzfCellGroupType) :: this
     ! -- local
@@ -1115,7 +1009,6 @@ subroutine setwaves(this, icell)
     real(DP) :: bottom, top
     integer(I4B) :: jk
     real(DP) :: thick
-! ------------------------------------------------------------------------------
     !
     ! -- initialize
     this%totflux(icell) = DZERO
@@ -1154,18 +1047,13 @@ subroutine setwaves(this, icell)
       this%uzthst(1, icell) = this%thtr(icell)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine
 
+  !> @brief Prepare and route waves over time step
+  !<
   subroutine routewaves(this, totfluxtot, delt, ietflag, icell, ierr)
-! ******************************************************************************
-! routewaves -- prepare and route waves over time step
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    !
     ! -- dummy
     class(UzfCellGroupType) :: this
     real(DP), intent(inout) :: totfluxtot
@@ -1176,7 +1064,6 @@ subroutine routewaves(this, totfluxtot, delt, ietflag, icell, ierr)
     ! -- local
     real(DP) :: thick, thickold
     integer(I4B) :: idelt, iwav, ik
-! ------------------------------------------------------------------------------
     !
     ! -- initialize
     this%totflux(icell) = DZERO
@@ -1201,17 +1088,13 @@ subroutine routewaves(this, totfluxtot, delt, ietflag, icell, ierr)
       totfluxtot = totfluxtot + this%totflux(icell)
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine routewaves
 
+  !> @brief Copy waves or shift waves in arrays
+  !<
   subroutine wave_shift(this, this2, icell, icell2, shft, strt, stp, cntr)
-! ******************************************************************************
-! wave_shift -- copy waves or shift waves in arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(UzfCellGroupType) :: this
     type(UzfCellGroupType) :: this2
@@ -1223,7 +1106,6 @@ subroutine wave_shift(this, this2, icell, icell2, shft, strt, stp, cntr)
     integer(I4B), intent(in) :: cntr
     ! -- local
     integer(I4B) :: j
-! ------------------------------------------------------------------------------
     !
     ! -- copy waves from one uzf cell group to another
     do j = strt, stp, cntr
@@ -1234,17 +1116,13 @@ subroutine wave_shift(this, this2, icell, icell2, shft, strt, stp, cntr)
     end do
     this%nwavst(icell) = this2%nwavst(icell2)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine
 
+  !> @brief Method of Characteristics solution for kinematic wave equation
+  !<
   subroutine uzflow(this, thick, thickold, delt, ietflag, icell, ierr)
-! ******************************************************************************
-! uzflow -- moc solution for kinematic wave equation
-! ******************************************************************************
-!     SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(UzfCellGroupType) :: this
     real(DP), intent(inout) :: thickold
@@ -1257,7 +1135,7 @@ subroutine uzflow(this, thick, thickold, delt, ietflag, icell, ierr)
     real(DP) :: ffcheck, time, feps1, feps2
     real(DP) :: thetadif, thetab, fluxb, oldsflx
     integer(I4B) :: itrailflg, itester
-! ------------------------------------------------------------------------------
+    !
     time = DZERO
     this%totflux(icell) = DZERO
     itrailflg = 0
@@ -1330,24 +1208,18 @@ subroutine uzflow(this, thick, thickold, delt, ietflag, icell, ierr)
     if (ietflag > 0) call this%uzet(icell, delt, ietflag, ierr)
     if (ierr > 0) return
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzflow
 
+  !> @brief Calculate unit specific tolerances
+  !<
   subroutine factors(feps1, feps2)
-! ******************************************************************************
-!   factors----calculate unit specific tolerances
-! ******************************************************************************
-!
-!     SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     real(DP), intent(out) :: feps1
     real(DP), intent(out) :: feps2
     real(DP) :: factor1
     real(DP) :: factor2
-! ------------------------------------------------------------------------------
     !
     ! calculate constants for uzflow
     factor1 = DONE
@@ -1367,18 +1239,13 @@ subroutine factors(feps1, feps2)
     feps1 = feps1 * factor1 * factor2
     feps2 = feps2 * factor1 * factor2
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine factors
 
+  !> @brief Create and set trail waves
+  !<
   subroutine trailwav(this, icell, ierr)
-! ******************************************************************************
-! trailwav----create and set trail waves
-! ******************************************************************************
-!
-!     SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell
@@ -1389,7 +1256,6 @@ subroutine trailwav(this, icell, ierr)
     real(DP) :: flux1, flux2, theta1, theta2
     real(DP) :: fnuminc
     integer(I4B) :: j, jj, jk, nwavstm1
-! ------------------------------------------------------------------------------
     !
     ! -- initialize
     eps_m1 = dble(this%eps(icell)) - DONE
@@ -1462,19 +1328,14 @@ subroutine trailwav(this, icell, ierr)
                   this%thtr(icell), this%eps(icell), this%vks(icell))
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine trailwav
 
+  !> @brief Create a lead wave and route over time step
+  !<
   subroutine leadwav(this, time, itester, itrailflg, thetab, fluxb, &
                      ffcheck, feps2, delt, icell)
-! ******************************************************************************
-! leadwav----create a lead wave and route over time step
-! ******************************************************************************
-!
-!     SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(UzfCellGroupType) :: this
     real(DP), intent(inout) :: thetab
@@ -1495,7 +1356,7 @@ subroutine leadwav(this, time, itester, itrailflg, thetab, fluxb, &
     integer(I4B) :: iflx, iremove, j, l
     integer(I4B) :: nwavp1, jshort
     integer(I4B), allocatable, dimension(:) :: more
-! ------------------------------------------------------------------------------
+    !
     allocate (checktime(this%nwavst(icell)))
     allocate (more(this%nwavst(icell)))
     ftest = DZERO
@@ -1671,19 +1532,14 @@ subroutine leadwav(this, time, itester, itrailflg, thetab, fluxb, &
     deallocate (checktime)
     deallocate (more)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine leadwav
 
+  !> @brief Calculates waves speed from dflux/dtheta
+  !<
   function leadspeed(theta1, theta2, flux1, flux2, thts, thtr, eps, vks)
-! ******************************************************************************
-! leadspeed----calculates waves speed from dflux/dtheta
-! ******************************************************************************
-!     SPECIFICATIONS:
-!
-! ------------------------------------------------------------------------------
-    ! -- modules
-    ! -- return
+    ! -- Return
     real(DP) :: leadspeed
     ! -- dummy
     real(DP), intent(in) :: theta1
@@ -1697,7 +1553,6 @@ function leadspeed(theta1, theta2, flux1, flux2, thts, thtr, eps, vks)
     ! -- local
     real(DP) :: comp1, comp2, thsrinv, epsfksths
     real(DP) :: eps_m1, fhold, comp3
-! ------------------------------------------------------------------------------
     !
     eps_m1 = eps - DONE
     thsrinv = DONE / (thts - thtr)
@@ -1715,19 +1570,14 @@ function leadspeed(theta1, theta2, flux1, flux2, thts, thtr, eps, vks)
     end if
     if (leadspeed < DEM30) leadspeed = DEM30
     !
-    ! -- return
+    ! -- Return
     return
   end function leadspeed
 
+  !> @brief Sums up mobile water over depth interval
+  !<
   function unsat_stor(this, icell, d1)
-! ******************************************************************************
-! unsat_stor---- sums up mobile water over depth interval
-! ******************************************************************************
-!     SPECIFICATIONS:
-!
-! ------------------------------------------------------------------------------
-    ! -- modules
-    ! -- return
+    ! -- Return
     real(DP) :: unsat_stor
     ! -- dummy
     class(UzfCellGroupType) :: this
@@ -1736,7 +1586,7 @@ function unsat_stor(this, icell, d1)
     ! -- local
     real(DP) :: fm
     integer(I4B) :: j, k, nwavm1, jj
-! ------------------------------------------------------------------------------
+    !
     fm = DZERO
     j = this%nwavst(icell) + 1
     k = this%nwavst(icell)
@@ -1766,16 +1616,14 @@ function unsat_stor(this, icell, d1)
       fm = fm + (this%uzthst(1, icell) - this%thtr(icell)) * d1
     end if
     unsat_stor = fm
+    !
+    ! -- Return
+    return
   end function unsat_stor
 
+  !> @brief Update to new state of uz at end of time step
+  !<
   subroutine update_wav(this, icell, delt, iss, itest)
-! ******************************************************************************
-! update_wav -- update to new state of uz at end of time step
-! ******************************************************************************
-!     SPECIFICATIONS:
-!
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell
@@ -1786,7 +1634,6 @@ subroutine update_wav(this, icell, delt, iss, itest)
     real(DP) :: bot, depthsave, top
     real(DP) :: thick, thtsrinv
     integer(I4B) :: nwavhld, k, j
-! ------------------------------------------------------------------------------
     !
     bot = this%watab(icell)
     top = this%celtop(icell)
@@ -1848,16 +1695,14 @@ subroutine update_wav(this, icell, delt, iss, itest)
       end if
       this%watabold(icell) = this%watab(icell)
     end if
+    !
+    ! -- Return
+    return
   end subroutine update_wav
 
+  !> @brief Remove water from uz due to et
+  !<
   subroutine uzet(this, icell, delt, ietflag, ierr)
-! ******************************************************************************
-!     uzet -- remove water from uz due to et
-! ******************************************************************************
-!     SPECIFICATIONS:
-!
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell
@@ -1894,7 +1739,6 @@ subroutine uzet(this, icell, delt, ietflag, ierr)
     integer(I4B) :: k
     integer(I4B) :: nwv
     integer(I4B) :: itest
-! ------------------------------------------------------------------------------
     !
     ! -- initialize
     this%etact(icell) = DZERO
@@ -2189,25 +2033,20 @@ subroutine uzet(this, icell, delt, ietflag, ierr)
     ! -- deallocate temporary worker
     call uzfktemp%dealloc()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine uzet
 
+  !> @brief Calculate capillary pressure head from B-C equation
+  !<
   function caph(this, icell, tho)
-! ******************************************************************************
-!     caph---- calculate capillary pressure head from B-C equation
-! ******************************************************************************
-!     SPECIFICATIONS:
-!
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell
     real(DP), intent(in) :: tho
     ! -- local
     real(DP) :: caph, lambda, star
-! ------------------------------------------------------------------------------
+    !
     caph = -DEM6
     star = (tho - this%thtr(icell)) / (this%thts(icell) - this%thtr(icell))
     if (star < DEM15) star = DEM15
@@ -2219,37 +2058,45 @@ function caph(this, icell, tho)
         caph = DZERO
       end if
     end if
+    !
+    ! -- Return
+    return
   end function caph
 
+  !> @brief Calculate capillary pressure-based uz et
   function rate_et_z(this, icell, factor, fktho, h)
-! ******************************************************************************
-!     rate_et_z---- capillary pressure based uz et
-! ******************************************************************************
-!     SPECIFICATIONS:
-!
-! ------------------------------------------------------------------------------
-    ! -- modules
-    ! -- return
+    ! -- Return
     real(DP) :: rate_et_z
     ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell
     real(DP), intent(in) :: factor, fktho, h
-    ! -- local
-! ------------------------------------------------------------------------------
+    !
     rate_et_z = factor * fktho * (h - this%hroot(icell))
     if (rate_et_z < DZERO) rate_et_z = DZERO
+    !
+    ! -- Return
+    return
   end function rate_et_z
 
+  !> @brief Determine the water content at a specific depth
+  !!
+  !! Because UZF-calculated waves are internal to UZF objects, different water
+  !! contents exists at different depths.
+  !<
   function get_water_content_at_depth(this, icell, depth) result(theta_at_depth)
+    ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell !< uzf cell containing depth
     real(DP), intent(in) :: depth !< depth within the cell
+    ! -- return
     real(DP) :: theta_at_depth
+    ! -- local
     real(DP) :: d1
     real(DP) :: d2
     real(DP) :: f1
     real(DP) :: f2
+    !
     if (this%watab(icell) < this%celtop(icell)) then
       if (this%celtop(icell) - depth > this%watab(icell)) then
         d1 = depth - DEM3
@@ -2263,14 +2110,20 @@ function get_water_content_at_depth(this, icell, depth) result(theta_at_depth)
     else
       theta_at_depth = this%thts(icell)
     end if
+    !
+    ! -- Return
     return
   end function get_water_content_at_depth
 
+  !> @brief Calculate and return the cell-based water content value
+  !<
   function get_wcnew(this, icell) result(watercontent)
+    ! -- dummy
     class(UzfCellGroupType) :: this
     integer(I4B), intent(in) :: icell !< uzf cell containing depth
-    !
+    ! -- return
     real(DP) :: watercontent
+    ! -- local
     real(DP) :: top
     real(DP) :: bot
     real(DP) :: theta_r
@@ -2292,6 +2145,8 @@ function get_wcnew(this, icell) result(watercontent)
     else
       watercontent = DZERO
     end if
+    !
+    ! -- Return
     return
   end function get_wcnew
 
diff --git a/src/Model/ModelUtilities/Xt3dAlgorithm.f90 b/src/Model/ModelUtilities/Xt3dAlgorithm.f90
index 19bbb70191e..3472f0b995a 100644
--- a/src/Model/ModelUtilities/Xt3dAlgorithm.f90
+++ b/src/Model/ModelUtilities/Xt3dAlgorithm.f90
@@ -9,52 +9,44 @@ module Xt3dAlgorithmModule
 
 contains
 
+  !> @brief Compute the "conductances" in the normal-flux expression for an
+  !! interface (modflow-usg version).  The cell on one side of the interface is
+  !! "cell 0", and the one on the other side is "cell 1".
+  !!
+  !! nnbrmx = maximum number of neighbors allowed for a cell.
+  !! nnbr0 = number of neighbors (local connections) for cell 0.
+  !! inbr0 = array with the list of neighbors for cell 0.
+  !! il01 = local node number of cell 1 with respect to cell 0.
+  !! vc0 = array of connection unit-vectors for cell 0 with its neighbors.
+  !! vn0 = array of unit normal vectors for cell 0's interfaces.
+  !! dl0 = array of lengths contributed by cell 0 to its connections with its
+  !!    neighbors.
+  !! dl0n = array of lengths contributed by cell 0's neighbors to their
+  !!    connections with cell 0.
+  !! ck0 = conductivity tensor for cell 0.
+  !! nnbr1 = number of neighbors (local connections) for cell 1.
+  !! inbr1 = array with the list of neighbors for cell 1.
+  !! il10 = local node number of cell 0 with respect to cell 1.
+  !! vc1 = array of connection unit-vectors for cell 1 with its neighbors.
+  !! vn1 = array of unit normal vectors for cell 1's interfaces.
+  !! dl1 = array of lengths contributed by cell 1 to its connections with its
+  !!    neighbors.
+  !! dl1n = array of lengths contributed by cell 1's neighbors to their
+  !!    connections with cell 1.
+  !! ck1 = conductivity tensor for cell1.
+  !! ar01 = area of interface (0,1).
+  !! ar10 = area of interface (1,0).
+  !! chat01 = "conductance" for connection (0,1).
+  !! chati0 = array of "conductances" for connections of cell 0.
+  !!    (zero for connection with cell 1, as this connection is
+  !!    already covered by chat01.)
+  !! chat1j = array of "conductances" for connections of cell 1.
+  !!    (zero for connection with cell 0., as this connection is
+  !!    already covered by chat01.)
+  !<
   subroutine qconds(nnbrmx, nnbr0, inbr0, il01, vc0, vn0, dl0, dl0n, ck0, &
                     nnbr1, inbr1, il10, vc1, vn1, dl1, dl1n, ck1, ar01, ar10, &
                     vcthresh, allhc0, allhc1, chat01, chati0, chat1j)
-! ******************************************************************************
-!
-!.....Compute the "conductances" in the normal-flux expression for an
-!        interface (modflow-usg version).  The cell on one side of
-!        the interface is "cell 0", and the one on the other side is
-!        "cell 1".
-!
-!        nnbrmx = maximum number of neighbors allowed for a cell.
-!        nnbr0 = number of neighbors (local connections) for cell 0.
-!        inbr0 = array with the list of neighbors for cell 0.
-!        il01 = local node number of cell 1 with respect to cell 0.
-!        vc0 = array of connection unit-vectors for cell 0 with its
-!           neighbors.
-!        vn0 = array of unit normal vectors for cell 0's interfaces.
-!        dl0 = array of lengths contributed by cell 0 to its
-!           connections with its neighbors.
-!        dl0n = array of lengths contributed by cell 0's neighbors to
-!           their connections with cell 0.
-!        ck0 = conductivity tensor for cell 0.
-!        nnbr1 = number of neighbors (local connections) for cell 1.
-!        inbr1 = array with the list of neighbors for cell 1.
-!        il10 = local node number of cell 0 with respect to cell 1.
-!        vc1 = array of connection unit-vectors for cell 1 with its
-!           neighbors.
-!        vn1 = array of unit normal vectors for cell 1's interfaces.
-!        dl1 = array of lengths contributed by cell 1 to its
-!           connections with its neighbors.
-!        dl1n = array of lengths contributed by cell 1's neighbors to
-!           their connections with cell 1.
-!        ck1 = conductivity tensor for cell1.
-!        ar01 = area of interface (0,1).
-!        ar10 = area of interface (1,0).
-!        chat01 = "conductance" for connection (0,1).
-!        chati0 = array of "conductances" for connections of cell 0.
-!           (zero for connection with cell 1, as this connection is
-!           already covered by chat01.)
-!        chat1j = array of "conductances" for connections of cell 1.
-!           (zero for connection with cell 0., as this connection is
-!           already covered by chat01.)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     integer(I4B) :: nnbrmx
     integer(I4B) :: nnbr0
@@ -91,31 +83,30 @@ subroutine qconds(nnbrmx, nnbr0, inbr0, il01, vc0, vn0, dl0, dl0n, ck0, &
     real(DP), dimension(nnbrmx) :: bhat0
     real(DP), dimension(nnbrmx) :: bhat1
     real(DP) :: denom
-! ------------------------------------------------------------------------------
-!
-!.....Set the global cell number for cell 1, as found in the neighbor
-!        list for cell 0.  It is assumed that cells 0 and 1 are both
-!        active, or else this subroutine would not have been called.
+    !
+    ! -- Set the global cell number for cell 1, as found in the neighbor list
+    !    for cell 0.  It is assumed that cells 0 and 1 are both active, or else
+    !    this subroutine would not have been called.
     i1 = inbr0(il01)
-!
-!.....If area ar01 is zero (in which case ar10 is also zero, since
-!        this can only happen here in the case of Newton), then the
-!        "conductances" are all zero.
+    !
+    ! -- If area ar01 is zero (in which case ar10 is also zero, since this can
+    !    only happen here in the case of Newton), then the "conductances" are
+    !    all zero.
     if (ar01 .eq. 0d0) then
       chat01 = 0d0
       do i = 1, nnbrmx
         chati0(i) = 0d0
         chat1j(i) = 0d0
       end do
-!.....Else compute "conductances."
+      ! -- Else compute "conductances."
     else
-!........Compute contributions from cell 0.
+      ! -- Compute contributions from cell 0.
       call abhats(nnbrmx, nnbr0, inbr0, il01, vc0, vn0, dl0, dl0n, ck0, &
                   vcthresh, allhc0, ar01, ahat0, bhat0)
-!........Compute contributions from cell 1.
+      ! -- Compute contributions from cell 1.
       call abhats(nnbrmx, nnbr1, inbr1, il10, vc1, vn1, dl1, dl1n, ck1, &
                   vcthresh, allhc1, ar10, ahat1, bhat1)
-!........Compute "conductances" based on the two flux estimates.
+      ! -- Compute "conductances" based on the two flux estimates.
       denom = (ahat0 + ahat1)
       if (abs(denom) > DPREC) then
         wght1 = ahat0 / (ahat0 + ahat1)
@@ -129,19 +120,15 @@ subroutine qconds(nnbrmx, nnbr0, inbr0, il01, vc0, vn0, dl0, dl0n, ck0, &
         chat1j(i) = wght1 * bhat1(i)
       end do
     end if
-!
+    !
+    ! -- Return
     return
   end subroutine qconds
 
+  !> @brief Compute "ahat" and "bhat" coefficients for one side of an interface
+  !<
   subroutine abhats(nnbrmx, nnbr, inbr, il01, vc, vn, dl0, dln, ck, &
                     vcthresh, allhc, ar01, ahat, bhat)
-! ******************************************************************************
-!.....Compute "ahat" and "bhat" coefficients for one side of an
-!        interface.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     integer(I4B) :: nnbrmx
     integer(I4B) :: nnbr
@@ -179,45 +166,42 @@ subroutine abhats(nnbrmx, nnbr, inbr, il01, vc, vn, dl0, dln, ck, &
     real(DP) :: alphad
     real(DP) :: alphae
     real(DP) :: dl0il
-! ------------------------------------------------------------------------------
-!
-!.....Determine the basis vectors for local "(c, d, e)" coordinates
-!        associated with the connection between cells 0 and 1, and
-!        set the rotation matrix that transforms vectors from model
-!        coordinates to (c, d, e) coordinates.  (If no active
-!        connection is found that has a non-negligible component
-!        perpendicular to the primary connection, ilmo=0 is returned.)
+    !
+    ! -- Determine the basis vectors for local "(c, d, e)" coordinates
+    !    associated with the connection between cells 0 and 1, and set the
+    !    rotation matrix that transforms vectors from model coordinates to
+    !    (c, d, e) coordinates.  (If no active connection is found that has a
+    !    non-negligible component perpendicular to the primary connection,
+    !    ilmo=0 is returned.)
     call getrot(nnbrmx, nnbr, inbr, vc, il01, rmat, iml0)
-!
-!.....If no active connection with a non-negligible perpendicular
-!        component, assume no perpendicular gradient and base gradient
-!        solely on the primary connection.  Otherwise, proceed with
-!        basing weights on information from neighboring connections.
+    !
+    ! -- If no active connection with a non-negligible perpendicular
+    !    component, assume no perpendicular gradient and base gradient solely
+    !    on the primary connection.  Otherwise, proceed with basing weights on
+    !    information from neighboring connections.
     if (iml0 .eq. 0) then
-!
-!........Compute ahat and bhat coefficients assuming perpendicular
-!           components of gradient are zero.
+      !
+      ! -- Compute ahat and bhat coefficients assuming perpendicular components
+      !    of gradient are zero.
       sigma(1) = dot_product(vn(il01, :), matmul(ck, rmat(:, 1)))
       ahat = sigma(1) / dl0(il01)
       bhat = 0d0
-!
     else
-!
-!........Transform local connection unit-vectors from model coordinates
-!           to "(c, d, e)" coordinates associated with the connection
-!           between cells 0 and 1.
+      !
+      ! -- Transform local connection unit-vectors from model coordinates to
+      !    "(c, d, e)" coordinates associated with the connection between cells
+      !    0 and 1.
       call tranvc(nnbrmx, nnbr, rmat, vc, vccde)
-!
-!........Get "a" and "b" weights for first perpendicular direction.
+      !
+      ! -- Get "a" and "b" weights for first perpendicular direction.
       call abwts(nnbrmx, nnbr, inbr, il01, 2, vccde, &
                  vcthresh, dl0, dln, acd, add, aed, bd)
-!
-!........If all neighboring connections are user-designated as
-!           horizontal, or if none have a non-negligible component in
-!           the second perpendicular direction, assume zero gradient in
-!           the second perpendicular direction.  Otherwise, get "a" and
-!           "b" weights for second perpendicular direction based on
-!           neighboring connections.
+      !
+      ! -- If all neighboring connections are user-designated as horizontal, or
+      !    if none have a non-negligible component in the second perpendicular
+      !    direction, assume zero gradient in the second perpendicular direction.
+      !    Otherwise, get "a" and "b" weights for second perpendicular direction
+      !    based on neighboring connections.
       if (allhc) then
         ace = 0d0
         aee = 1d0
@@ -243,8 +227,8 @@ subroutine abhats(nnbrmx, nnbr, inbr, il01, vc, vn, dl0, dln, ck, &
           be = 0d0
         end if
       end if
-!
-!........Compute alpha and beta coefficients.
+      !
+      ! -- Compute alpha and beta coefficients.
       determ = add * aee - ade * aed
       oodet = 1d0 / determ
       alphad = (acd * aee - ace * aed) * oodet
@@ -252,62 +236,57 @@ subroutine abhats(nnbrmx, nnbr, inbr, il01, vc, vn, dl0, dln, ck, &
       betad = 0d0
       betae = 0d0
       do il = 1, nnbr
-!...........If this is connection (0,1) or inactive, skip.
+        ! -- If this is connection (0,1) or inactive, skip.
         if ((il == il01) .or. (inbr(il) == 0)) cycle
         betad(il) = (bd(il) * aee - be(il) * aed) * oodet
         betae(il) = (be(il) * add - bd(il) * ade) * oodet
       end do
-!
-!........Compute sigma coefficients.
+      !
+      ! -- Compute sigma coefficients.
       sigma = matmul(vn(il01, :), matmul(ck, rmat))
-!
-!........Compute ahat and bhat coefficients.
+      !
+      ! -- Compute ahat and bhat coefficients.
       ahat = (sigma(1) - sigma(2) * alphad - sigma(3) * alphae) / dl0(il01)
       bhat = 0d0
       do il = 1, nnbr
-!...........If this is connection (0,1) or inactive, skip.
+        ! -- If this is connection (0,1) or inactive, skip.
         if ((il == il01) .or. (inbr(il) == 0)) cycle
         dl0il = dl0(il) + dln(il)
         bhat(il) = (sigma(2) * betad(il) + sigma(3) * betae(il)) / dl0il
       end do
-!........Set the bhat for connection (0,1) to zero here, since we have
-!           been skipping it in our do loops to avoiding explicitly
-!           computing it.  This will carry through to the corresponding
-!           chati0 and chat1j value, so that they too are zero.
+      ! -- Set the bhat for connection (0,1) to zero here, since we have been
+      !    skipping it in our do loops to avoiding explicitly computing it.
+      !    This will carry through to the corresponding chati0 and chat1j value,
+      !    so that they too are zero.
       bhat(il01) = 0d0
-!
+      !
     end if
-!
-!.....Multiply by area.
+    !
+    ! -- Multiply by area.
     ahat = ahat * ar01
     bhat = bhat * ar01
-!
+    !
+    ! -- Return
     return
   end subroutine abhats
 
+  !> @brief Compute the matrix that rotates the model-coordinate axes to the
+  !! "(c, d, e)-coordinate" axes associated with a connection.
+  !!
+  !! This is also the matrix that transforms the components of a vector
+  !! from (c, d, e) coordinates to model coordinates.  [Its transpose
+  !! transforms from model to (c, d, e) coordinates.]
+  !!
+  !!    vcc = unit vector for the primary connection, in model coordinates.
+  !!    vcd = unit vector for the first perpendicular direction, in model
+  !!       coordinates.
+  !!    vce = unit vector for the second perpendicular direction, in model
+  !!       coordinates.
+  !!    vcmax = unit vector for the connection with the maximum component
+  !!       perpendicular to the primary connection, in model coordinates.
+  !!    rmat = rotation matrix from model to (c, d, e) coordinates.
+  !<
   subroutine getrot(nnbrmx, nnbr, inbr, vc, il01, rmat, iml0)
-! ******************************************************************************
-!.....Compute the matrix that rotates the model-coordinate axes to
-!     the "(c, d, e)-coordinate" axes associated with a connection.
-!     This is also the matrix that transforms the components of a vector
-!     from (c, d, e) coordinates to model coordinates.  [Its transpose
-!     transforms from model to (c, d, e) coordinates.]
-!
-!        vcc = unit vector for the primary connection, in model
-!           coordinates.
-!        vcd = unit vector for the first perpendicular direction,
-!           in model coordinates.
-!        vce = unit vector for the second perpendicular direction,
-!           in model coordinates.
-!        vcmax = unit vector for the connection with the maximum
-!           component perpendicular to the primary connection,
-!           in model coordinates.
-!        rmat = rotation matrix from model to (c, d, e) coordinates.
-!
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     integer(I4B) :: nnbrmx
     integer(I4B) :: nnbr
@@ -326,15 +305,13 @@ subroutine getrot(nnbrmx, nnbr, inbr, vc, il01, rmat, iml0)
     real(DP) :: cmp
     real(DP) :: acmp
     real(DP) :: cmpmn
-! ------------------------------------------------------------------------------
-!
-!.....set vcc.
+    !
+    ! -- Set vcc.
     vcc(:) = vc(il01, :)
-!
-!.....Set vcmax.  (If no connection has a perpendicular component
-!        greater than some tiny threshold, return with iml0=0 and
-!        the first column of rmat set to vcc -- the other columns
-!        are not needed.)
+    !
+    ! -- Set vcmax. (If no connection has a perpendicular component greater
+    !    than some tiny threshold, return with iml0=0 and the first column of
+    !    rmat set to vcc -- the other columns are not needed.)
     acmpmn = 1d0 - 1d-10
     iml0 = 0
     do il = 1, nnbr
@@ -356,43 +333,37 @@ subroutine getrot(nnbrmx, nnbr, inbr, vc, il01, rmat, iml0)
     else
       vcmax(:) = vc(iml0, :)
     end if
-!
-!.....Set the first perpendicular direction as the direction that is
-!        coplanar with vcc and vcmax and perpendicular to vcc.
+    !
+    ! -- Set the first perpendicular direction as the direction that is coplanar
+    !    with vcc and vcmax and perpendicular to vcc.
     vcd = vcmax - cmpmn * vcc
     vcd = vcd / dsqrt(1d0 - cmpmn * cmpmn)
-!
-!.....Set the second perpendicular direction as the cross product of
-!        the primary and first-perpendicular directions.
+    !
+    ! -- Set the second perpendicular direction as the cross product of the
+    !    primary and first-perpendicular directions.
     vce(1) = vcc(2) * vcd(3) - vcc(3) * vcd(2)
     vce(2) = vcc(3) * vcd(1) - vcc(1) * vcd(3)
     vce(3) = vcc(1) * vcd(2) - vcc(2) * vcd(1)
-!
-!.....Set the rotation matrix as the matrix with vcc, vcd, and vce
-!        as its columns.
+    !
+    ! -- Set the rotation matrix as the matrix with vcc, vcd, and vce as its
+    !    columns.
     rmat(:, 1) = vcc(:)
     rmat(:, 2) = vcd(:)
     rmat(:, 3) = vce(:)
-!
+    !
+    ! -- Return
 999 return
   end subroutine getrot
 
+  !> @brief Transform local connection unit-vectors from model coordinates to
+  !! "(c, d, e)" coordinates associated with a connection.
+  !!
+  !! nnbrs = number of neighbors (local connections)
+  !! rmat = rotation matrix from (c, d, e) to model coordinates.
+  !! vc = array of connection unit-vectors with respect to model coordinates.
+  !! vccde = array of connection unit-vectors with respect to (c, d, e)
+  !!         coordinates.
   subroutine tranvc(nnbrmx, nnbrs, rmat, vc, vccde)
-! ******************************************************************************
-!.....Transform local connection unit-vectors from model coordinates
-!        to "(c, d, e)" coordinates associated with a connection.
-!
-!        nnbrs = number of neighbors (local connections)
-!        rmat = rotation matrix from (c, d, e) to model coordinates.
-!        vc = array of connection unit-vectors with respect to model
-!           coordinates.
-!        vccde = array of connection unit-vectors with respect to
-!           (c, d, e) coordinates.
-!
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     integer(I4B) :: nnbrmx
     integer(I4B) :: nnbrs
@@ -401,39 +372,31 @@ subroutine tranvc(nnbrmx, nnbrs, rmat, vc, vccde)
     real(DP), dimension(nnbrmx, 3) :: vccde
     ! -- local
     integer(I4B) :: il
-! ------------------------------------------------------------------------------
-!
-!.....Loop over the local connections, transforming the unit vectors.
-!        Note that we are multiplying by the transpose of the
-!        rotation matrix so that the transformation is from model
-!        to (c, d, e) coordinates.
+    !
+    ! -- Loop over the local connections, transforming the unit vectors.
+    !    Note that we are multiplying by the transpose of the rotation matrix
+    !    so that the transformation is from model to (c, d, e) coordinates.
     do il = 1, nnbrs
       vccde(il, :) = matmul(transpose(rmat), vc(il, :))
     end do
-!
+    !
+    ! -- Return
     return
   end subroutine tranvc
 
+  !> @brief Compute "a" and "b" weights for the local connections with respect
+  !! to the perpendicular direction of primary interest.
+  !!
+  !! nde1 = number that indicates the perpendicular direction of primary
+  !!        interest on this call: "d" (2) or "e" (3).
+  !! vccde = array of connection unit-vectors with respect to (c, d, e)
+  !!         coordinates.
+  !! bd = array of "b" weights.
+  !! aed = "a" weight that goes on the matrix side of the 2x2 problem.
+  !! acd = "a" weight that goes on the right-hand side of the 2x2 problem.
+  !<
   subroutine abwts(nnbrmx, nnbr, inbr, il01, nde1, vccde, &
                    vcthresh, dl0, dln, acd, add, aed, bd)
-! ******************************************************************************
-!.....Compute "a" and "b" weights for the local connections with respect
-!        to the perpendicular direction of primary interest.
-!
-!        nde1 = number that indicates the perpendicular direction of
-!           primary interest on this call: "d" (2) or "e" (3).
-!        vccde = array of connection unit-vectors with respect to
-!           (c, d, e) coordinates.
-!        bd = array of "b" weights.
-!        aed = "a" weight that goes on the matrix side of the 2x2
-!           problem.
-!        acd = "a" weight that goes on the right-hand side of the
-!           2x2 problem.
-!
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     integer(I4B) :: nnbrmx
     integer(I4B) :: nnbr
@@ -460,80 +423,79 @@ subroutine abwts(nnbrmx, nnbr, inbr, il01, nde1, vccde, &
     real(DP) :: oodsum
     real(DP) :: fatten
     real(DP), dimension(nnbrmx) :: omwt
-! ------------------------------------------------------------------------------
-!
-!.....Set the perpendicular direction of secondary interest.
+    !
+    ! -- Set the perpendicular direction of secondary interest.
     nde2 = 5 - nde1
-!
-!.....Begin computing "omega" weights.
+    !
+    ! -- Begin computing "omega" weights.
     omwt = 0d0
     dsum = 0d0
     vcmx = 0d0
     do il = 1, nnbr
-!........if this is connection (0,1) or inactive, skip.
+      ! -- If this is connection (0,1) or inactive, skip.
       if ((il .eq. il01) .or. (inbr(il) .eq. 0)) cycle
       vcmx = max(dabs(vccde(il, nde1)), vcmx)
       dlm = 5d-1 * (dl0(il) + dln(il))
-!...........Distance-based weighting.  dl4wt is the distance between
-!              the point supplying the gradient information and the
-!              point at which the flux is being estimated.  Could be
-!              coded as a special case of resistance-based weighting
-!              (by setting the conductivity matrix to be the identity
-!              matrix), but this is more efficient.
+      ! -- Distance-based weighting.  dl4wt is the distance between the point
+      !    supplying the gradient information and the point at which the flux is
+      !    being estimated. Could be coded as a special case of resistance-based
+      !    weighting (by setting the conductivity matrix to be the identity
+      !    matrix), but this is more efficient.
       cosang = vccde(il, 1)
       dl4wt = dsqrt(dlm * dlm + dl0(il01) * dl0(il01) &
                     - 2d0 * dlm * dl0(il01) * cosang)
       omwt(il) = dabs(vccde(il, nde1)) * dl4wt
       dsum = dsum + omwt(il)
     end do
-!
-!.....Finish computing non-normalized "omega" weights.  [Add a
-!        tiny bit to dsum so that the normalized omega weight later
-!        evaluates to (essentially) 1 in the case of a single relevant
-!        connection, avoiding 0/0.]
+    !
+    ! -- Finish computing non-normalized "omega" weights.  [Add a tiny bit to
+    !    dsum so that the normalized omega weight later evaluates to
+    !    (essentially) 1 in the case of a single relevant connection, avoiding
+    !    0/0.]
     dsum = dsum + 1d-10 * dsum
     do il = 1, nnbr
-!........If this is connection (0,1) or inactive, skip.
+      ! -- If this is connection (0,1) or inactive, skip.
       if ((il .eq. il01) .or. (inbr(il) .eq. 0)) cycle
       fact = dsum - omwt(il)
       omwt(il) = fact * dabs(vccde(il, nde1))
     end do
-!
-!.....Compute "b" weights.
+    !
+    ! -- Compute "b" weights.
     bd = 0d0
     dsum = 0d0
     do il = 1, nnbr
-!........If this is connection (0,1) or inactive, skip.
+      ! -- If this is connection (0,1) or inactive, skip.
       if ((il .eq. il01) .or. (inbr(il) .eq. 0)) cycle
       bd(il) = omwt(il) * sign(1d0, vccde(il, nde1))
       dsum = dsum + omwt(il) * dabs(vccde(il, nde1))
     end do
+    !
     oodsum = 1d0 / dsum
     do il = 1, nnbr
-!........If this is connection (0,1) or inactive, skip.
+      ! -- If this is connection (0,1) or inactive, skip.
       if ((il .eq. il01) .or. (inbr(il) .eq. 0)) cycle
       bd(il) = bd(il) * oodsum
     end do
-!
-!.....Compute "a" weights.
+    !
+    ! -- Compute "a" weights.
     add = 1d0
     acd = 0d0
     aed = 0d0
     do il = 1, nnbr
-!........If this is connection (0,1) or inactive, skip.
+      ! -- If this is connection (0,1) or inactive, skip.
       if ((il .eq. il01) .or. (inbr(il) .eq. 0)) cycle
       acd = acd + bd(il) * vccde(il, 1)
       aed = aed + bd(il) * vccde(il, nde2)
     end do
-!
-!.....Apply attenuation function to acd, aed, and bd.
+    !
+    ! -- Apply attenuation function to acd, aed, and bd.
     if (vcmx .lt. vcthresh) then
       fatten = vcmx / vcthresh
       acd = acd * fatten
       aed = aed * fatten
       bd = bd * fatten
     end if
-!
+    !
   end subroutine abwts
-!
+
 end module Xt3dAlgorithmModule
diff --git a/src/Model/ModelUtilities/Xt3dInterface.f90 b/src/Model/ModelUtilities/Xt3dInterface.f90
index df87f773fc3..f7ca17e1e81 100644
--- a/src/Model/ModelUtilities/Xt3dInterface.f90
+++ b/src/Model/ModelUtilities/Xt3dInterface.f90
@@ -11,6 +11,7 @@ module Xt3dModule
   public :: xt3d_cr
 
   type Xt3dType
+
     character(len=LENMEMPATH) :: memoryPath !< location in memory manager for storing package variables
     integer(I4B), pointer :: inunit => null() !< unit number from where xt3d was read
     integer(I4B), pointer :: iout => null() !< unit number for output
@@ -48,7 +49,9 @@ module Xt3dModule
     real(DP), dimension(:), pointer, contiguous :: angle2 => null() !< k ellipse rotation up from xy plane around y axis (pitch)
     real(DP), dimension(:), pointer, contiguous :: angle3 => null() !< k tensor rotation around x axis (roll)
     logical, pointer :: ldispersion => null() !< flag to indicate dispersion
+
   contains
+
     procedure :: xt3d_df
     procedure :: xt3d_ac
     procedure :: xt3d_mc
@@ -76,30 +79,25 @@ module Xt3dModule
     procedure, private :: xt3d_rhs
     procedure, private :: xt3d_fillrmatck
     procedure, private :: xt3d_qnbrs
+
   end type Xt3dType
 
 contains
 
+  !> @brief Create a new xt3d object
+  !<
   subroutine xt3d_cr(xt3dobj, name_model, inunit, iout, ldispopt)
-! ******************************************************************************
-! xt3d_cr -- Create a new xt3d object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(Xt3dType), pointer :: xt3dobj
     character(len=*), intent(in) :: name_model
     integer(I4B), intent(in) :: inunit
     integer(I4B), intent(in) :: iout
     logical, optional, intent(in) :: ldispopt
-! ------------------------------------------------------------------------------
     !
     ! -- Create the object
     allocate (xt3dobj)
     !
-
-    ! -- assign the memory path
+    ! -- Assign the memory path
     xt3dobj%memoryPath = create_mem_path(name_model, 'XT3D')
     !
     ! -- Allocate scalars
@@ -114,18 +112,12 @@ subroutine xt3d_cr(xt3dobj, name_model, inunit, iout, ldispopt)
     return
   end subroutine xt3d_cr
 
+  !> @brief Define the xt3d object
+  !<
   subroutine xt3d_df(this, dis)
-! ******************************************************************************
-! xt3d_df -- define the xt3d object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(Xt3dType) :: this
     class(DisBaseType), pointer, intent(inout) :: dis
-! ------------------------------------------------------------------------------
     !
     this%dis => dis
     !
@@ -133,13 +125,9 @@ subroutine xt3d_df(this, dis)
     return
   end subroutine xt3d_df
 
+  !> @brief Add connections for extended neighbors to the sparse matrix
+  !<
   subroutine xt3d_ac(this, moffset, sparse)
-! ******************************************************************************
-! xt3d_ac -- Add connections for extended neighbors to the sparse matrix
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SparseModule, only: sparsematrix
     use MemoryManagerModule, only: mem_allocate
@@ -152,17 +140,15 @@ subroutine xt3d_ac(this, moffset, sparse)
     integer(I4B) :: i, j, k, jj, kk, iglo, kglo, iadded
     integer(I4B) :: nnz
     integer(I4B) :: ierror
-! ------------------------------------------------------------------------------
     !
     ! -- If not rhs, add connections
     if (this%ixt3d == 1) then
-
-      ! -- assume nnz is 19, which is an approximate value
+      ! -- Assume nnz is 19, which is an approximate value
       !    based on a 3d structured grid
       nnz = 19
       call sparse_xt3d%init(this%dis%nodes, this%dis%nodes, nnz)
-
-      ! -- loop over nodes and store extended xt3d neighbors
+      !
+      ! -- Loop over nodes and store extended xt3d neighbors
       !    temporarily in sparse_xt3d; this will be converted to
       !    ia_xt3d and ja_xt3d next
       do i = 1, this%dis%nodes
@@ -178,7 +164,7 @@ subroutine xt3d_ac(this, moffset, sparse)
           end do
         end do
       end do
-
+      !
       ! -- calculate ia_xt3d and ja_xt3d from sparse_xt3d and
       !    then destroy sparse
       call mem_allocate(this%ia_xt3d, this%dis%nodes + 1, 'IA_XT3D', &
@@ -209,13 +195,9 @@ subroutine xt3d_ac(this, moffset, sparse)
     return
   end subroutine xt3d_ac
 
+  !> @brief Map connections and construct iax, jax, and idxglox
+  !<
   subroutine xt3d_mc(this, moffset, matrix_sln)
-! ******************************************************************************
-! xt3d_mc -- Map connections and construct iax, jax, and idxglox
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
@@ -228,7 +210,6 @@ subroutine xt3d_mc(this, moffset, matrix_sln)
     integer(I4B) :: jj_xt3d
     integer(I4B) :: igfirstnod, iglastnod
     logical :: isextnbr
-! ------------------------------------------------------------------------------
     !
     ! -- If not rhs, map connections for extended neighbors and construct iax,
     ! -- jax, and idxglox
@@ -301,14 +282,10 @@ subroutine xt3d_mc(this, moffset, matrix_sln)
     return
   end subroutine xt3d_mc
 
+  !> @brief Allocate and Read
+  !<
   subroutine xt3d_ar(this, ibound, k11, ik33, k33, sat, ik22, k22, iangle1, &
                      iangle2, iangle3, angle1, angle2, angle3, inewton, icelltype)
-! ******************************************************************************
-! xt3d_ar -- Allocate and Read
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SimModule, only: store_error
     ! -- dummy
@@ -334,8 +311,6 @@ subroutine xt3d_ar(this, ibound, k11, ik33, k33, sat, ik22, k22, iangle1, &
     ! -- formats
     character(len=*), parameter :: fmtheader = &
                                    "(1x, /1x, 'XT3D is active.'//)"
-    ! -- data
-! ------------------------------------------------------------------------------
     !
     ! -- Print a message identifying the xt3d module.
     if (this%iout > 0) then
@@ -356,6 +331,7 @@ subroutine xt3d_ar(this, ibound, k11, ik33, k33, sat, ik22, k22, iangle1, &
     this%angle1 => angle1
     this%angle2 => angle2
     this%angle3 => angle3
+    !
     if (present(inewton)) then
       ! -- inewton is not needed for transport so it's optional.
       this%inewton = inewton
@@ -406,13 +382,9 @@ subroutine xt3d_ar(this, ibound, k11, ik33, k33, sat, ik22, k22, iangle1, &
     return
   end subroutine xt3d_ar
 
+  !> @brief Formulate
   subroutine xt3d_fc(this, kiter, matrix_sln, idxglo, rhs, hnew)
-! ******************************************************************************
-! xt3d_fc -- Formulate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use ConstantsModule, only: DONE
     use Xt3dAlgorithmModule, only: qconds
     ! -- dummy
@@ -425,7 +397,6 @@ subroutine xt3d_fc(this, kiter, matrix_sln, idxglo, rhs, hnew)
     ! -- local
     integer(I4B) :: nodes, nja
     integer(I4B) :: n, m, ipos
-    !
     logical :: allhc0, allhc1
     integer(I4B) :: nnbr0, nnbr1
     integer(I4B) :: il0, ii01, jjs01, il01, il10, ii00, ii11, ii10
@@ -438,7 +409,6 @@ subroutine xt3d_fc(this, kiter, matrix_sln, idxglo, rhs, hnew)
     real(DP) :: chat01
     real(DP), dimension(this%nbrmax) :: chati0, chat1j
     real(DP) :: qnm, qnbrs
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate xt3d conductance-like coefficients and put into amat and rhs
     ! -- as appropriate
@@ -466,7 +436,7 @@ subroutine xt3d_fc(this, kiter, matrix_sln, idxglo, rhs, hnew)
       call this%xt3d_load(nodes, n, nnbr0, inbr0, vc0, vn0, dl0, dl0n, &
                           ck0, allhc0)
       ! -- Loop over active neighbors of cell 0 that have a higher
-      ! -- cell number (taking advantage of reciprocity).
+      !    cell number (taking advantage of reciprocity).
       do il0 = 1, nnbr0
         ipos = this%dis%con%ia(n) + il0
         if (this%dis%con%mask(ipos) == 0) cycle
@@ -489,13 +459,13 @@ subroutine xt3d_fc(this, kiter, matrix_sln, idxglo, rhs, hnew)
           call this%xt3d_areas(nodes, n, m, jjs01, .false., ar01, ar10, hnew)
         end if
         ! -- Compute "conductances" for interface between
-        ! -- cells 0 and 1.
+        !    cells 0 and 1.
         call qconds(this%nbrmax, nnbr0, inbr0, il01, vc0, vn0, dl0, dl0n, ck0, &
                     nnbr1, inbr1, il10, vc1, vn1, dl1, dl1n, ck1, ar01, ar10, &
                     this%vcthresh, allhc0, allhc1, chat01, chati0, chat1j)
         ! -- If Newton, compute and save saturated flow, then scale
-        ! -- conductance-like coefficients by the actual area for
-        ! -- subsequent amat and rhs assembly.
+        !    conductance-like coefficients by the actual area for
+        !    subsequent amat and rhs assembly.
         if (this%inewton /= 0) then
           ! -- Contribution to flow from primary connection.
           qnm = chat01 * (hnew(m) - hnew(n))
@@ -514,6 +484,7 @@ subroutine xt3d_fc(this, kiter, matrix_sln, idxglo, rhs, hnew)
           chati0 = chati0 * ar01
           chat1j = chat1j * ar01
         end if
+        !
         ! -- Contribute to rows for cells 0 and 1.
         call matrix_sln%add_value_pos(idxglo(ii00), -chat01)
         call matrix_sln%add_value_pos(idxglo(ii01), chat01)
@@ -540,14 +511,10 @@ subroutine xt3d_fc(this, kiter, matrix_sln, idxglo, rhs, hnew)
     return
   end subroutine xt3d_fc
 
+  !> @brief Formulate for permanently confined connections and save in amatpc
+  !! and amatpcx
+  !<
   subroutine xt3d_fcpc(this, nodes, lsat)
-! ******************************************************************************
-! xt3d_fcpc -- Formulate for permanently confined connections and save in
-!              amatpc and amatpcx
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use Xt3dAlgorithmModule, only: qconds
     ! -- dummy
@@ -567,7 +534,6 @@ subroutine xt3d_fcpc(this, nodes, lsat)
     real(DP), dimension(3, 3) :: ck0, ck1
     real(DP) :: chat01
     real(DP), dimension(this%nbrmax) :: chati0, chat1j
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize amatpc and amatpcx to zero
     do n = 1, size(this%amatpc)
@@ -626,14 +592,11 @@ subroutine xt3d_fcpc(this, nodes, lsat)
     return
   end subroutine xt3d_fcpc
 
+  !> @brief Formulate HFB correction
+  !<
   subroutine xt3d_fhfb(this, kiter, nodes, nja, matrix_sln, idxglo, rhs, hnew, &
                        n, m, condhfb)
-! ******************************************************************************
-! xt3d_fhfb -- Formulate HFB correction
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use ConstantsModule, only: DONE
     use Xt3dAlgorithmModule, only: qconds
     ! -- dummy
@@ -648,7 +611,6 @@ subroutine xt3d_fhfb(this, kiter, nodes, nja, matrix_sln, idxglo, rhs, hnew, &
     real(DP), intent(inout), dimension(nodes) :: hnew
     real(DP) :: condhfb
     ! -- local
-    !
     logical :: allhc0, allhc1
     integer(I4B) :: nnbr0, nnbr1
     integer(I4B) :: il0, ii01, jjs01, il01, il10, ii00, ii11, ii10, il
@@ -661,10 +623,9 @@ subroutine xt3d_fhfb(this, kiter, nodes, nja, matrix_sln, idxglo, rhs, hnew, &
     real(DP), dimension(this%nbrmax) :: chati0, chat1j
     real(DP) :: qnm, qnbrs
     real(DP) :: term
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate hfb corrections to xt3d conductance-like coefficients and
-    ! -- put into amat and rhs as appropriate
+    !    put into amat and rhs as appropriate
     !
     nnbr0 = this%dis%con%ia(n + 1) - this%dis%con%ia(n) - 1
     ! -- Load conductivity and connection info for cell 0.
@@ -691,11 +652,13 @@ subroutine xt3d_fhfb(this, kiter, nodes, nja, matrix_sln, idxglo, rhs, hnew, &
     else
       call this%xt3d_areas(nodes, n, m, jjs01, .false., ar01, ar10, hnew)
     end if
+    !
     ! -- Compute "conductances" for interface between
-    ! -- cells 0 and 1.
+    !    cells 0 and 1.
     call qconds(this%nbrmax, nnbr0, inbr0, il01, vc0, vn0, dl0, dl0n, &
                 ck0, nnbr1, inbr1, il10, vc1, vn1, dl1, dl1n, ck1, ar01, ar10, &
                 this%vcthresh, allhc0, allhc1, chat01, chati0, chat1j)
+    !
     ! -- Apply scale factor to compute "conductances" for hfb correction
     if (condhfb > DZERO) then
       term = chat01 / (chat01 + condhfb)
@@ -705,9 +668,9 @@ subroutine xt3d_fhfb(this, kiter, nodes, nja, matrix_sln, idxglo, rhs, hnew, &
     chat01 = -chat01 * term
     chati0 = -chati0 * term
     chat1j = -chat1j * term
-    ! -- If Newton, compute and save saturated flow, then scale
-    ! -- conductance-like coefficients by the actual area for
-    ! -- subsequent amat and rhs assembly.
+    !
+    ! -- If Newton, compute and save saturated flow, then scale conductance-like
+    !    coefficients by the actual area for subsequent amat and rhs assembly.
     if (this%inewton /= 0) then
       ! -- Contribution to flow from primary connection.
       qnm = chat01 * (hnew(m) - hnew(n))
@@ -726,6 +689,7 @@ subroutine xt3d_fhfb(this, kiter, nodes, nja, matrix_sln, idxglo, rhs, hnew, &
       chati0 = chati0 * ar01
       chat1j = chat1j * ar01
     end if
+    !
     ! -- Contribute to rows for cells 0 and 1.
     call matrix_sln%add_value_pos(idxglo(ii00), -chat01)
     call matrix_sln%add_value_pos(idxglo(ii01), chat01)
@@ -749,13 +713,9 @@ subroutine xt3d_fhfb(this, kiter, nodes, nja, matrix_sln, idxglo, rhs, hnew, &
     return
   end subroutine xt3d_fhfb
 
+  !> @brief Fill Newton terms for xt3d
   subroutine xt3d_fn(this, kiter, nodes, nja, matrix_sln, idxglo, rhs, hnew)
-! ******************************************************************************
-! xt3d_fn -- Fill Newton terms for xt3d
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use ConstantsModule, only: DONE
     use SmoothingModule, only: sQuadraticSaturationDerivative
     ! -- dummy
@@ -769,47 +729,53 @@ subroutine xt3d_fn(this, kiter, nodes, nja, matrix_sln, idxglo, rhs, hnew)
     real(DP), intent(inout), dimension(nodes) :: hnew
     ! -- local
     integer(I4B) :: n, m, ipos
-    !
     integer(I4B) :: nnbr0
     integer(I4B) :: il0, ii01, jjs01, il01, il10, ii00, ii11, ii10
     integer(I4B), dimension(this%nbrmax) :: inbr0
     integer(I4B) :: iups, idn
     real(DP) :: topup, botup, derv, term
-! ------------------------------------------------------------------------------
     !
     ! -- Update amat and rhs with Newton terms
     do n = 1, nodes
+      !
       ! -- Skip if inactive.
       if (this%ibound(n) .eq. 0) cycle
+      !
       ! -- No Newton correction if amat saved (which implies no rhs option)
-      ! -- and all connections for the cell are permanently confined.
+      !    and all connections for the cell are permanently confined.
       if (this%lamatsaved) then
         if (this%iallpc(n) == 1) cycle
       end if
       nnbr0 = this%dis%con%ia(n + 1) - this%dis%con%ia(n) - 1
+      !
       ! -- Load neighbors of cell. Set cell numbers for inactive
-      ! -- neighbors to zero.
+      !    neighbors to zero.
       call this%xt3d_load_inbr(n, nnbr0, inbr0)
+      !
       ! -- Loop over active neighbors of cell 0 that have a higher
-      ! -- cell number (taking advantage of reciprocity).
+      !    cell number (taking advantage of reciprocity).
       do il0 = 1, nnbr0
         ipos = this%dis%con%ia(n) + il0
         if (this%dis%con%mask(ipos) == 0) cycle
-
+        !
         m = inbr0(il0)
+        !
         ! -- Skip if neighbor is inactive or has lower cell number.
         if ((inbr0(il0) .eq. 0) .or. (m .lt. n)) cycle
+        !
         ! -- Set various indices.
         call this%xt3d_indices(n, m, il0, ii01, jjs01, il01, il10, &
                                ii00, ii11, ii10)
-        ! determine upstream node
+        !
+        ! -- Determine upstream node
         iups = m
         if (hnew(m) < hnew(n)) iups = n
         idn = n
         if (iups == n) idn = m
-        ! -- no Newton terms if upstream cell is confined
-        ! -- and no rhs option
+        !
+        ! -- No Newton terms if upstream cell is confined and no rhs option
         if ((this%icelltype(iups) == 0) .and. (this%ixt3d .eq. 1)) cycle
+        !
         ! -- Set the upstream top and bot, and then recalculate for a
         !    vertically staggered horizontal connection
         topup = this%dis%top(iups)
@@ -818,25 +784,33 @@ subroutine xt3d_fn(this, kiter, nodes, nja, matrix_sln, idxglo, rhs, hnew)
           topup = min(this%dis%top(n), this%dis%top(m))
           botup = max(this%dis%bot(n), this%dis%bot(m))
         end if
-        ! derivative term
+        !
+        ! -- Derivative term
         derv = sQuadraticSaturationDerivative(topup, botup, hnew(iups))
         term = this%qsat(ii01) * derv
-        ! fill Jacobian for n being the upstream node
+        !
+        ! -- Fill Jacobian for n being the upstream node
         if (iups == n) then
-          ! fill in row of n
+          !
+          ! -- Fill in row of n
           call matrix_sln%add_value_pos(idxglo(ii00), term)
           rhs(n) = rhs(n) + term * hnew(n)
-          ! fill in row of m
+          !
+          ! -- Fill in row of m
           call matrix_sln%add_value_pos(idxglo(ii10), -term)
           rhs(m) = rhs(m) - term * hnew(n)
-          ! fill Jacobian for m being the upstream node
+          !
+          ! -- Fill Jacobian for m being the upstream node
         else
-          ! fill in row of n
+          !
+          ! -- Fill in row of n
           call matrix_sln%add_value_pos(idxglo(ii01), term)
           rhs(n) = rhs(n) + term * hnew(m)
-          ! fill in row of m
+          !
+          ! -- Fill in row of m
           call matrix_sln%add_value_pos(idxglo(ii11), -term)
           rhs(m) = rhs(m) - term * hnew(m)
+          !
         end if
       end do
     end do
@@ -845,13 +819,10 @@ subroutine xt3d_fn(this, kiter, nodes, nja, matrix_sln, idxglo, rhs, hnew)
     return
   end subroutine xt3d_fn
 
+  !> @brief Budget
+  !<
   subroutine xt3d_flowja(this, hnew, flowja)
-! ******************************************************************************
-! xt3d_flowja -- Budget
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use Xt3dAlgorithmModule, only: qconds
     ! -- dummy
     class(Xt3dType) :: this
@@ -870,44 +841,54 @@ subroutine xt3d_flowja(this, hnew, flowja)
     real(DP), dimension(3, 3) :: ck0, ck1
     real(DP) :: chat01
     real(DP), dimension(this%nbrmax) :: chati0, chat1j
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate the flow across each cell face and store in flowja
     nodes = this%dis%nodes
     do n = 1, nodes
+      !
       ! -- Skip if inactive.
       if (this%ibound(n) .eq. 0) cycle
       nnbr0 = this%dis%con%ia(n + 1) - this%dis%con%ia(n) - 1
+      !
       ! -- Load conductivity and connection info for cell 0.
       call this%xt3d_load(nodes, n, nnbr0, inbr0, vc0, vn0, dl0, dl0n, &
                           ck0, allhc0)
+      !
       ! -- Loop over active neighbors of cell 0 that have a higher
-      ! -- cell number (taking advantage of reciprocity).
+      !    cell number (taking advantage of reciprocity).
       do il0 = 1, nnbr0
         m = inbr0(il0)
+        !
         ! -- Skip if neighbor is inactive or has lower cell number.
         if ((inbr0(il0) .eq. 0) .or. (m .lt. n)) cycle
         nnbr1 = this%dis%con%ia(m + 1) - this%dis%con%ia(m) - 1
+        !
         ! -- Load conductivity and connection info for cell 1.
         call this%xt3d_load(nodes, m, nnbr1, inbr1, vc1, vn1, dl1, dl1n, &
                             ck1, allhc1)
+        !
         ! -- Set various indices.
         call this%xt3d_indices(n, m, il0, ii01, jjs01, il01, il10, &
                                ii00, ii11, ii10)
+        !
         ! -- Compute areas.
         if (this%inewton /= 0) &
           call this%xt3d_areas(nodes, n, m, jjs01, .true., ar01, ar10, hnew)
         call this%xt3d_areas(nodes, n, m, jjs01, .false., ar01, ar10, hnew)
+        !
         ! -- Compute "conductances" for interface between
-        ! -- cells 0 and 1.
+        !    cells 0 and 1.
         call qconds(this%nbrmax, nnbr0, inbr0, il01, vc0, vn0, dl0, dl0n, ck0, &
                     nnbr1, inbr1, il10, vc1, vn1, dl1, dl1n, ck1, ar01, ar10, &
                     this%vcthresh, allhc0, allhc1, chat01, chati0, chat1j)
+        !
         ! -- Contribution to flow from primary connection.
         qnm = chat01 * (hnew(m) - hnew(n))
+        !
         ! -- Contribution from immediate neighbors of node 0.
         call this%xt3d_qnbrs(nodes, n, m, nnbr0, inbr0, chati0, hnew, qnbrs)
         qnm = qnm + qnbrs
+        !
         ! -- Contribution from immediate neighbors of node 1.
         call this%xt3d_qnbrs(nodes, m, n, nnbr1, inbr1, chat1j, hnew, qnbrs)
         qnm = qnm - qnbrs
@@ -921,13 +902,10 @@ subroutine xt3d_flowja(this, hnew, flowja)
     return
   end subroutine xt3d_flowja
 
+  !> @brief hfb contribution to flowja when xt3d is used
+  !<
   subroutine xt3d_flowjahfb(this, n, m, hnew, flowja, condhfb)
-! ******************************************************************************
-! xt3d_flowjahfb -- hfb contribution to flowja when xt3d is used
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use ConstantsModule, only: DONE
     use Xt3dAlgorithmModule, only: qconds
     ! -- dummy
@@ -937,10 +915,9 @@ subroutine xt3d_flowjahfb(this, n, m, hnew, flowja, condhfb)
     real(DP), intent(inout), dimension(:) :: flowja
     real(DP) :: condhfb
     ! -- local
-    !
     integer(I4B) :: nodes
     logical :: allhc0, allhc1
-!!!    integer(I4B), parameter :: nbrmax = 10
+    ! integer(I4B), parameter :: nbrmax = 10
     integer(I4B) :: nnbr0, nnbr1
     integer(I4B) :: il0, ii01, jjs01, il01, il10, ii00, ii11, ii10, il
     integer(I4B), dimension(this%nbrmax) :: inbr0, inbr1
@@ -953,16 +930,16 @@ subroutine xt3d_flowjahfb(this, n, m, hnew, flowja, condhfb)
     real(DP), dimension(this%nbrmax) :: chati0, chat1j
     real(DP) :: qnm, qnbrs
     real(DP) :: term
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate hfb corrections to xt3d conductance-like coefficients and
-    ! -- put into amat and rhs as appropriate
-    !
+    !    put into amat and rhs as appropriate
     nodes = this%dis%nodes
     nnbr0 = this%dis%con%ia(n + 1) - this%dis%con%ia(n) - 1
+    !
     ! -- Load conductivity and connection info for cell 0.
     call this%xt3d_load(nodes, n, nnbr0, inbr0, vc0, vn0, dl0, dl0n, &
                         ck0, allhc0)
+    !
     ! -- Find local neighbor number of cell 1.
     do il = 1, nnbr0
       if (inbr0(il) .eq. m) then
@@ -970,13 +947,17 @@ subroutine xt3d_flowjahfb(this, n, m, hnew, flowja, condhfb)
         exit
       end if
     end do
+    !
     nnbr1 = this%dis%con%ia(m + 1) - this%dis%con%ia(m) - 1
+    !
     ! -- Load conductivity and connection info for cell 1.
     call this%xt3d_load(nodes, m, nnbr1, inbr1, vc1, vn1, dl1, dl1n, &
                         ck1, allhc1)
+    !
     ! -- Set various indices.
     call this%xt3d_indices(n, m, il0, ii01, jjs01, il01, il10, &
                            ii00, ii11, ii10)
+    !
     ! -- Compute areas.
     if (this%inewton /= 0) then
       ar01 = DONE
@@ -984,11 +965,13 @@ subroutine xt3d_flowjahfb(this, n, m, hnew, flowja, condhfb)
     else
       call this%xt3d_areas(nodes, n, m, jjs01, .false., ar01, ar10, hnew)
     end if
+    !
     ! -- Compute "conductances" for interface between
-    ! -- cells 0 and 1.
+    !    cells 0 and 1.
     call qconds(this%nbrmax, nnbr0, inbr0, il01, vc0, vn0, dl0, dl0n, &
                 ck0, nnbr1, inbr1, il10, vc1, vn1, dl1, dl1n, ck1, ar01, ar10, &
                 this%vcthresh, allhc0, allhc1, chat01, chati0, chat1j)
+    !
     ! -- Apply scale factor to compute "conductances" for hfb correction
     if (condhfb > DZERO) then
       term = chat01 / (chat01 + condhfb)
@@ -998,21 +981,26 @@ subroutine xt3d_flowjahfb(this, n, m, hnew, flowja, condhfb)
     chat01 = -chat01 * term
     chati0 = -chati0 * term
     chat1j = -chat1j * term
+    !
     ! -- Contribution to flow from primary connection.
     qnm = chat01 * (hnew(m) - hnew(n))
+    !
     ! -- Contribution from immediate neighbors of node 0.
     call this%xt3d_qnbrs(nodes, n, m, nnbr0, inbr0, chati0, hnew, qnbrs)
     qnm = qnm + qnbrs
+    !
     ! -- Contribution from immediate neighbors of node 1.
     call this%xt3d_qnbrs(nodes, m, n, nnbr1, inbr1, chat1j, hnew, qnbrs)
     qnm = qnm - qnbrs
+    !
     ! -- If Newton, scale conductance-like coefficients by the
-    ! -- actual area.
+    !    actual area.
     if (this%inewton /= 0) then
       call this%xt3d_areas(nodes, n, m, jjs01, .true., ar01, ar10, hnew)
       call this%xt3d_areas(nodes, n, m, jjs01, .false., ar01, ar10, hnew)
       qnm = qnm * ar01
     end if
+    !
     ipos = ii01
     flowja(ipos) = flowja(ipos) + qnm
     flowja(this%dis%con%isym(ipos)) = flowja(this%dis%con%isym(ipos)) - qnm
@@ -1021,18 +1009,13 @@ subroutine xt3d_flowjahfb(this, n, m, hnew, flowja, condhfb)
     return
   end subroutine xt3d_flowjahfb
 
+  !> @brief Deallocate variables
+  !<
   subroutine xt3d_da(this)
-! ******************************************************************************
-! xt3d_da -- Deallocate variables
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
     class(Xt3dType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Deallocate arrays
     if (this%ixt3d /= 0) then
@@ -1064,18 +1047,13 @@ subroutine xt3d_da(this)
     return
   end subroutine xt3d_da
 
+  !> @brief Allocate scalar pointer variables
+  !<
   subroutine allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars -- Allocate scalar pointer variables
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
     class(Xt3dType) :: this
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate scalars
     call mem_allocate(this%ixt3d, 'IXT3D', this%memoryPath)
@@ -1105,13 +1083,9 @@ subroutine allocate_scalars(this)
     return
   end subroutine allocate_scalars
 
+  !> @brief Allocate xt3d arrays
+  !<
   subroutine allocate_arrays(this)
-! ******************************************************************************
-! allocate_arrays -- Allocate xt3d arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
@@ -1119,7 +1093,6 @@ subroutine allocate_arrays(this)
     ! -- local
     integer(I4B) :: njax
     integer(I4B) :: n
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate Newton-dependent arrays
     if (this%inewton /= 0) then
@@ -1174,13 +1147,8 @@ subroutine allocate_arrays(this)
     return
   end subroutine allocate_arrays
 
+  !> @brief Allocate and populate iallpc array. Set lamatsaved.
   subroutine xt3d_iallpc(this)
-! ******************************************************************************
-! xt3d_iallpc -- Allocate and populate iallpc array. Set lamatsaved.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate, mem_deallocate
     ! -- dummy
@@ -1189,7 +1157,6 @@ subroutine xt3d_iallpc(this)
     integer(I4B) :: n, m, mm, il0, il1
     integer(I4B) :: nnbr0, nnbr1
     integer(I4B), dimension(this%nbrmax) :: inbr0, inbr1
-! ------------------------------------------------------------------------------
     !
     if (this%ixt3d == 2) then
       this%lamatsaved = .false.
@@ -1253,27 +1220,21 @@ subroutine xt3d_iallpc(this)
     return
   end subroutine xt3d_iallpc
 
+  !> @brief Set various indices for XT3D.
+  !<
   subroutine xt3d_indices(this, n, m, il0, ii01, jjs01, il01, il10, &
                           ii00, ii11, ii10)
-! ******************************************************************************
-! xt3d_indices -- Set various indices for XT3D.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- module
     ! -- dummy
     class(Xt3dType) :: this
     integer(I4B) :: n, m, il0, ii01, jjs01, il01, il10, ii00, ii11, ii10
     ! -- local
     integer(I4B) :: iinm
-! ------------------------------------------------------------------------------
     !
     ! -- Set local number of node 0-1 connection (local cell number of cell 1
-    ! -- in cell 0's neighbor list).
+    !    in cell 0's neighbor list).
     il01 = il0
     ! -- Set local number of node 1-0 connection (local cell number of cell 0
-    ! -- in cell 1's neighbor list).
+    !    in cell 1's neighbor list).
     call this%xt3d_get_iinm(m, n, iinm)
     il10 = iinm - this%dis%con%ia(m)
     ! -- Set index of node 0 diagonal in the ja array.
@@ -1287,17 +1248,14 @@ subroutine xt3d_indices(this, n, m, il0, ii01, jjs01, il01, il10, &
     ! -- Set index of node 1-0 connection in the ja array.
     ii10 = ii11 + il10
     !
+    ! -- Return
     return
   end subroutine xt3d_indices
 
+  !> @brief Load conductivity and connection info for a cell into arrays used
+  !! by XT3D
+  !<
   subroutine xt3d_load(this, nodes, n, nnbr, inbr, vc, vn, dl, dln, ck, allhc)
-! ******************************************************************************
-! xt3d_load -- Load conductivity and connection info for a cell into arrays
-!              used by XT3D.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- module
     use ConstantsModule, only: DZERO, DHALF, DONE
     ! -- dummy
@@ -1314,7 +1272,6 @@ subroutine xt3d_load(this, nodes, n, nnbr, inbr, vc, vn, dl, dln, ck, allhc)
     integer(I4B) :: ihcnjj
     real(DP) :: satn, satjj
     real(DP) :: cl1njj, cl2njj, dltot, ooclsum
-! ------------------------------------------------------------------------------
     !
     ! -- Set conductivity tensor for cell.
     ck = DZERO
@@ -1325,11 +1282,10 @@ subroutine xt3d_load(this, nodes, n, nnbr, inbr, vc, vn, dl, dln, ck, allhc)
     ck = matmul(this%rmatck, ck)
     ck = matmul(ck, transpose(this%rmatck))
     !
-    ! -- Load neighbors of cell. Set cell numbers for inactive
-    ! -- neighbors to zero so xt3d knows to ignore them. Compute
-    ! -- direct connection lengths from perpendicular connection
-    ! -- lengths. Also determine if all active connections are
-    ! -- horizontal.
+    ! -- Load neighbors of cell. Set cell numbers for inactive neighbors to
+    !    zero so xt3d knows to ignore them. Compute direct connection lengths
+    !    from perpendicular connection lengths. Also determine if all active
+    !    connections are horizontal.
     allhc = .true.
     do il = 1, nnbr
       ii = il + this%dis%con%ia(n)
@@ -1339,6 +1295,7 @@ subroutine xt3d_load(this, nodes, n, nnbr, inbr, vc, vn, dl, dln, ck, allhc)
         inbr(il) = jj
         satn = this%sat(n)
         satjj = this%sat(jj)
+        !
         ! -- DISV and DIS
         ihcnjj = this%dis%con%ihc(jjs)
         call this%dis%connection_normal(n, jj, ihcnjj, vn(il, 1), vn(il, 2), &
@@ -1361,27 +1318,22 @@ subroutine xt3d_load(this, nodes, n, nnbr, inbr, vc, vn, dl, dln, ck, allhc)
       end if
     end do
     !
+    ! -- Return
     return
   end subroutine xt3d_load
 
+  !> @brief Load neighbor list for a cell.
+  !<
   subroutine xt3d_load_inbr(this, n, nnbr, inbr)
-! ******************************************************************************
-! xt3d_load_inbr -- Load neighbor list for a cell.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- module
     ! -- dummy
     class(Xt3dType) :: this
     integer(I4B) :: n, nnbr
     integer(I4B), dimension(this%nbrmax) :: inbr
     ! -- local
     integer(I4B) :: il, ii, jj
-! ------------------------------------------------------------------------------
     !
     ! -- Load neighbors of cell. Set cell numbers for inactive
-    ! -- neighbors to zero so xt3d knows to ignore them.
+    !    neighbors to zero so xt3d knows to ignore them.
     do il = 1, nnbr
       ii = il + this%dis%con%ia(n)
       jj = this%dis%con%ja(ii)
@@ -1392,17 +1344,13 @@ subroutine xt3d_load_inbr(this, n, nnbr, inbr)
       end if
     end do
     !
+    ! -- Return
     return
   end subroutine xt3d_load_inbr
 
+  !> @brief Compute interfacial areas.
+  !<
   subroutine xt3d_areas(this, nodes, n, m, jjs01, lsat, ar01, ar10, hnew)
-! ******************************************************************************
-! xt3d_areas -- Compute interfacial areas.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- module
     ! -- dummy
     class(Xt3dType) :: this
     logical :: lsat
@@ -1413,12 +1361,11 @@ subroutine xt3d_areas(this, nodes, n, m, jjs01, lsat, ar01, ar10, hnew)
     real(DP) :: topn, botn, topm, botm, thksatn, thksatm
     real(DP) :: sill_top, sill_bot, tpn, tpm
     real(DP) :: satups
-! ------------------------------------------------------------------------------
     !
     ! -- Compute area depending on connection type
     if (this%dis%con%ihc(jjs01) == 0) then
       !
-      ! -- vertical connection
+      ! -- Vertical connection
       ar01 = this%dis%con%hwva(jjs01)
       ar10 = ar01
     else if (this%inewton /= 0) then
@@ -1434,7 +1381,7 @@ subroutine xt3d_areas(this, nodes, n, m, jjs01, lsat, ar01, ar10, hnew)
         thksatn = topn - botn
         thksatm = topm - botm
         if (this%dis%con%ihc(jjs01) .eq. 2) then
-          ! -- vertically staggered
+          ! -- Vertically staggered
           sill_top = min(topn, topm)
           sill_bot = max(botn, botm)
           tpn = botn + thksatn
@@ -1445,9 +1392,9 @@ subroutine xt3d_areas(this, nodes, n, m, jjs01, lsat, ar01, ar10, hnew)
         ar01 = this%dis%con%hwva(jjs01) * DHALF * (thksatn + thksatm)
       else
         ! -- If Newton and lsat=.false., it is assumed that the fully saturated
-        ! -- areas have already been calculated and are being passed in through
-        ! -- ar01 and ar10. The actual areas are obtained simply by scaling by
-        ! -- the upstream saturation.
+        !    areas have already been calculated and are being passed in through
+        !    ar01 and ar10. The actual areas are obtained simply by scaling by
+        !    the upstream saturation.
         if (hnew(m) < hnew(n)) then
           satups = this%sat(n)
         else
@@ -1470,7 +1417,7 @@ subroutine xt3d_areas(this, nodes, n, m, jjs01, lsat, ar01, ar10, hnew)
         thksatm = this%sat(m) * thksatm
       end if
       if (this%dis%con%ihc(jjs01) == 2) then
-        ! -- vertically staggered
+        ! -- Vertically staggered
         sill_top = min(topn, topm)
         sill_bot = max(botn, botm)
         tpn = botn + thksatn
@@ -1482,18 +1429,14 @@ subroutine xt3d_areas(this, nodes, n, m, jjs01, lsat, ar01, ar10, hnew)
       ar10 = this%dis%con%hwva(jjs01) * thksatm
     end if
     !
+    ! -- Return
     return
   end subroutine xt3d_areas
 
+  !> @brief Add contributions from neighbors to amat.
+  !<
   subroutine xt3d_amat_nbrs(this, nodes, n, idiag, nnbr, nja, &
                             matrix_sln, inbr, idxglo, chat)
-! ******************************************************************************
-! xt3d_amat_nbrs -- Add contributions from neighbors to amat.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- module
     ! -- dummy
     class(Xt3dType) :: this
     integer(I4B), intent(in) :: nodes
@@ -1504,7 +1447,6 @@ subroutine xt3d_amat_nbrs(this, nodes, n, idiag, nnbr, nja, &
     real(DP), dimension(this%nbrmax) :: chat
     ! -- local
     integer(I4B) :: iil, iii
-! ------------------------------------------------------------------------------
     !
     do iil = 1, nnbr
       if (inbr(iil) .ne. 0) then
@@ -1514,18 +1456,14 @@ subroutine xt3d_amat_nbrs(this, nodes, n, idiag, nnbr, nja, &
       end if
     end do
     !
+    ! -- Return
     return
   end subroutine xt3d_amat_nbrs
 
+  !> @brief Add contributions from neighbors of neighbor to amat.
+  !<
   subroutine xt3d_amat_nbrnbrs(this, nodes, n, m, ii01, nnbr, nja, &
                                matrix_sln, inbr, idxglo, chat)
-! ******************************************************************************
-! xt3d_amat_nbrnbrs -- Add contributions from neighbors of neighbor to amat.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- module
     ! -- dummy
     class(Xt3dType) :: this
     integer(I4B), intent(in) :: nodes
@@ -1536,7 +1474,6 @@ subroutine xt3d_amat_nbrnbrs(this, nodes, n, m, ii01, nnbr, nja, &
     real(DP), dimension(this%nbrmax) :: chat
     ! -- local
     integer(I4B) :: iil, iii, jjj, iixjjj, iijjj
-! ------------------------------------------------------------------------------
     !
     do iil = 1, nnbr
       if (inbr(iil) .ne. 0) then
@@ -1553,17 +1490,13 @@ subroutine xt3d_amat_nbrnbrs(this, nodes, n, m, ii01, nnbr, nja, &
       end if
     end do
     !
+    ! -- Return
     return
   end subroutine xt3d_amat_nbrnbrs
 
+  !> @brief Add contributions from neighbors to amatpc.
+  !<
   subroutine xt3d_amatpc_nbrs(this, nodes, n, idiag, nnbr, inbr, chat)
-! ******************************************************************************
-! xt3d_amatpc_nbrs -- Add contributions from neighbors to amatpc.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- module
     ! -- dummy
     class(Xt3dType) :: this
     integer(I4B), intent(in) :: nodes
@@ -1572,7 +1505,6 @@ subroutine xt3d_amatpc_nbrs(this, nodes, n, idiag, nnbr, inbr, chat)
     real(DP), dimension(this%nbrmax) :: chat
     ! -- local
     integer(I4B) :: iil, iii
-! ------------------------------------------------------------------------------
     !
     do iil = 1, nnbr
       iii = this%dis%con%ia(n) + iil
@@ -1580,18 +1512,13 @@ subroutine xt3d_amatpc_nbrs(this, nodes, n, idiag, nnbr, inbr, chat)
       this%amatpc(iii) = this%amatpc(iii) + chat(iil)
     end do
     !
+    ! -- Return
     return
   end subroutine xt3d_amatpc_nbrs
 
+  !> @brief Add contributions from neighbors of neighbor to amatpc and amatpcx
+  !<
   subroutine xt3d_amatpcx_nbrnbrs(this, nodes, n, m, ii01, nnbr, inbr, chat)
-! ******************************************************************************
-! xt3d_amatpcx_nbrnbrs -- Add contributions from neighbors of neighbor to
-!   amatpc and amatpcx.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- module
     ! -- dummy
     class(Xt3dType) :: this
     integer(I4B), intent(in) :: nodes
@@ -1600,7 +1527,6 @@ subroutine xt3d_amatpcx_nbrnbrs(this, nodes, n, m, ii01, nnbr, inbr, chat)
     real(DP), dimension(this%nbrmax) :: chat
     ! -- local
     integer(I4B) :: iil, iii, jjj, iixjjj, iijjj
-! ------------------------------------------------------------------------------
     !
     do iil = 1, nnbr
       this%amatpc(ii01) = this%amatpc(ii01) + chat(iil)
@@ -1615,24 +1541,19 @@ subroutine xt3d_amatpcx_nbrnbrs(this, nodes, n, m, ii01, nnbr, inbr, chat)
       end if
     end do
     !
+    ! -- Return
     return
   end subroutine xt3d_amatpcx_nbrnbrs
 
+  !> @brief Get position of n-m connection in ja array (return 0 if not
+  !! connected)
+  !<
   subroutine xt3d_get_iinm(this, n, m, iinm)
-! ******************************************************************************
-! xt3d_get_iinm -- Get position of n-m connection in ja array (return 0 if
-!   not connected).
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- module
     ! -- dummy
     class(Xt3dType) :: this
     integer(I4B) :: n, m, iinm
     ! -- local
     integer(I4B) :: ii, jj
-! ------------------------------------------------------------------------------
     !
     iinm = 0
     do ii = this%dis%con%ia(n), this%dis%con%ia(n + 1) - 1
@@ -1643,24 +1564,19 @@ subroutine xt3d_get_iinm(this, n, m, iinm)
       end if
     end do
     !
+    ! -- Return
     return
   end subroutine xt3d_get_iinm
 
+  !> @brief Get position of n-m "extended connection" in jax array (return 0 if
+  !! not connected)
+  !<
   subroutine xt3d_get_iinmx(this, n, m, iinmx)
-! ******************************************************************************
-! xt3d_get_iinmx -- Get position of n-m "extended connection" in jax array
-!   (return 0 if not connected).
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- module
     ! -- dummy
     class(Xt3dType) :: this
     integer(I4B) :: n, m, iinmx
     ! -- local
     integer(I4B) :: iix, jjx
-! ------------------------------------------------------------------------------
     !
     iinmx = 0
     do iix = this%iax(n), this%iax(n + 1) - 1
@@ -1671,18 +1587,14 @@ subroutine xt3d_get_iinmx(this, n, m, iinmx)
       end if
     end do
     !
+    ! -- Return
     return
   end subroutine xt3d_get_iinmx
 
+  !> @brief Add contributions to rhs.
+  !<
   subroutine xt3d_rhs(this, nodes, n, m, nnbr, inbr, chat, hnew, &
                       rhs)
-! ******************************************************************************
-! xt3d_rhs -- Add contributions to rhs.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- module
     ! -- dummy
     class(Xt3dType) :: this
     integer(I4B), intent(in) :: nodes
@@ -1693,7 +1605,6 @@ subroutine xt3d_rhs(this, nodes, n, m, nnbr, inbr, chat, hnew, &
     ! -- local
     integer(I4B) :: iil, iii, jjj
     real(DP) :: term
-! ------------------------------------------------------------------------------
     !
     do iil = 1, nnbr
       if (inbr(iil) .ne. 0) then
@@ -1705,18 +1616,14 @@ subroutine xt3d_rhs(this, nodes, n, m, nnbr, inbr, chat, hnew, &
       end if
     end do
     !
+    ! -- Return
     return
   end subroutine xt3d_rhs
 
+  !> @brief Add contributions to flow from neighbors
+  !<
   subroutine xt3d_qnbrs(this, nodes, n, m, nnbr, inbr, chat, hnew, &
                         qnbrs)
-! ******************************************************************************
-! xt3d_qnbrs -- Add contributions to flow from neighbors.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- module
     ! -- dummy
     class(Xt3dType) :: this
     integer(I4B), intent(in) :: nodes
@@ -1728,7 +1635,6 @@ subroutine xt3d_qnbrs(this, nodes, n, m, nnbr, inbr, chat, hnew, &
     ! -- local
     integer(I4B) :: iil, iii, jjj
     real(DP) :: term
-! ------------------------------------------------------------------------------
     !
     qnbrs = 0d0
     do iil = 1, nnbr
@@ -1740,25 +1646,21 @@ subroutine xt3d_qnbrs(this, nodes, n, m, nnbr, inbr, chat, hnew, &
       end if
     end do
     !
+    ! -- Return
     return
   end subroutine xt3d_qnbrs
 
+  !> @brief Fill rmat array for cell n.
+  !!
+  !!   angle1, 2, and 3 must be in radians.
+  !<
   subroutine xt3d_fillrmatck(this, n)
-! ******************************************************************************
-! xt3d_fillrmatck -- Fill rmat array for cell n.
-!   angle1, 2, and 3 must be in radians.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- module
     ! -- dummy
     class(Xt3dType) :: this
     integer(I4B), intent(in) :: n
     ! -- local
     real(DP) :: ang1, ang2, ang3, ang2d, ang3d
     real(DP) :: s1, c1, s2, c2, s3, c3
-! ------------------------------------------------------------------------------
     !
     if (this%nozee) then
       ang2d = 0d0
@@ -1787,6 +1689,7 @@ subroutine xt3d_fillrmatck(this, n)
     this%rmatck(3, 2) = -c2 * s3
     this%rmatck(3, 3) = c2 * c3
     !
+    ! -- Return
     return
   end subroutine xt3d_fillrmatck
 
diff --git a/src/Model/NumericalModel.f90 b/src/Model/NumericalModel.f90
index 59ccf46ec76..e4d5e0e5add 100644
--- a/src/Model/NumericalModel.f90
+++ b/src/Model/NumericalModel.f90
@@ -48,6 +48,7 @@ module NumericalModelModule
     procedure :: model_mc
     procedure :: model_rp
     procedure :: model_ad
+    procedure :: model_reset
     procedure :: model_cf
     procedure :: model_fc
     procedure :: model_ptcchk
@@ -106,6 +107,20 @@ subroutine model_ad(this)
     class(NumericalModelType) :: this
   end subroutine model_ad
 
+  subroutine model_reset(this)
+    use BndModule, only: BndType, GetBndFromList
+    class(NumericalModelType) :: this
+    ! local
+    class(BndType), pointer :: packobj
+    integer(I4B) :: ip
+
+    do ip = 1, this%bndlist%Count()
+      packobj => GetBndFromList(this%bndlist, ip)
+      call packobj%bnd_reset()
+    end do
+
+  end subroutine model_reset
+
   subroutine model_cf(this, kiter)
     class(NumericalModelType) :: this
     integer(I4B), intent(in) :: kiter
diff --git a/src/Model/NumericalPackage.f90 b/src/Model/NumericalPackage.f90
index 114256a4778..ee9c81fd048 100644
--- a/src/Model/NumericalPackage.f90
+++ b/src/Model/NumericalPackage.f90
@@ -6,7 +6,7 @@
 !<
 module NumericalPackageModule
   ! -- modules
-  use KindModule, only: DP, I4B
+  use KindModule, only: DP, I4B, LGP
   use ConstantsModule, only: LENPACKAGENAME, LENMODELNAME, &
                              LENMEMPATH, LENFTYPE, LINELENGTH, &
                              LENVARNAME
@@ -28,7 +28,7 @@ module NumericalPackageModule
     character(len=LENMEMPATH) :: memoryPath = '' !< the location in the memory manager where the variables are stored
     character(len=LENMEMPATH) :: memoryPathModel = '' !< the location in the memory manager where the variables
                                                                                  !! of the parent model are stored
-    character(len=LENMEMPATH), pointer :: input_mempath => null() !< input context mempath
+    character(len=LENMEMPATH) :: input_mempath = '' !< input context mempath
     character(len=LINELENGTH), pointer :: input_fname => null() !< input file name
     character(len=LENFTYPE) :: filtyp = '' !< file type (CHD, DRN, RIV, etc.)
     character(len=LENFTYPE), pointer :: package_type => null() !< package type (same as filtyp) stored in memory manager
@@ -60,23 +60,25 @@ module NumericalPackageModule
 contains
   !
   !> @ brief Set package names
-    !!
-    !!  Method to assign the filtyp (ftype), the model name, and package name for
-    !!  a package. This method also creates the memoryPath and memoryPathModel that
-    !!  is used by the memory manager when variables are allocated.
-    !!
+  !!
+  !!  Method to assign the filtyp (ftype), the model name, and package name for
+  !!  a package. This method also creates the memoryPath and memoryPathModel that
+  !!  is used by the memory manager when variables are allocated.
+  !!
   !<
-  subroutine set_names(this, ibcnum, name_model, pakname, ftype)
+  subroutine set_names(this, ibcnum, name_model, pakname, ftype, input_mempath)
     ! -- dummy variables
     class(NumericalPackageType), intent(inout) :: this !< NumericalPackageType object
     integer(I4B), intent(in) :: ibcnum !< unique package number
     character(len=*), intent(in) :: name_model !< name of the model
     character(len=*), intent(in) :: pakname !< name of the package
     character(len=*), intent(in) :: ftype !< package type
+    character(len=*), optional, intent(in) :: input_mempath !< input_mempath
     !
     ! -- set names
     this%filtyp = ftype
     this%name_model = name_model
+    if (present(input_mempath)) this%input_mempath = input_mempath
     if (pakname == '') then
       write (this%packName, '(a, i0)') trim(ftype)//'-', ibcnum
     else
@@ -93,19 +95,17 @@ subroutine set_names(this, ibcnum, name_model, pakname, ftype)
     end if
     this%memoryPath = create_mem_path(name_model, this%packName)
     this%memoryPathModel = create_mem_path(name_model)
-    !
-    ! -- return
-    return
   end subroutine set_names
 
   !> @ brief Allocate package scalars
-    !!
-    !!  Allocate and initialize base numerical package scalars.
-    !!
+  !!
+  !!  Allocate and initialize base numerical package scalars.
+  !!
   !<
   subroutine allocate_scalars(this)
     ! -- modules
     use MemoryManagerModule, only: mem_allocate, mem_setptr
+    use MemoryManagerExtModule, only: mem_set_value
     ! -- dummy variables
     class(NumericalPackageType) :: this !< NumericalPackageType object
     ! -- local variables
@@ -113,10 +113,9 @@ subroutine allocate_scalars(this)
     integer(I4B), pointer :: imodelprpak => null()
     integer(I4B), pointer :: imodelprflow => null()
     integer(I4B), pointer :: imodelpakcb => null()
+    logical(LGP) :: found
     !
     ! -- allocate scalars
-    call mem_allocate(this%input_mempath, LENMEMPATH, 'INPUT_MEMPATH', &
-                      this%memoryPath)
     call mem_allocate(this%input_fname, LINELENGTH, 'INPUT_FNAME', &
                       this%memoryPath)
     call mem_allocate(this%package_type, LENFTYPE, 'PACKAGE_TYPE', &
@@ -140,7 +139,6 @@ subroutine allocate_scalars(this)
     call mem_setptr(imodelpakcb, 'IPAKCB', this%memoryPathModel)
     !
     ! -- initialize
-    this%input_mempath = ''
     this%input_fname = ''
     this%package_type = this%filtyp
     this%id = 0
@@ -160,14 +158,17 @@ subroutine allocate_scalars(this)
     imodelprflow => null()
     imodelpakcb => null()
     !
-    ! -- return
-    return
+    ! -- update input filename
+    if (this%input_mempath /= '') then
+      call mem_set_value(this%input_fname, 'INPUT_FNAME', &
+                         this%input_mempath, found)
+    end if
   end subroutine allocate_scalars
 
   !> @ brief Deallocate package scalars
-    !!
-    !!  Deallocate and initialize base numerical package scalars.
-    !!
+  !!
+  !!  Deallocate and initialize base numerical package scalars.
+  !!
   !<
   subroutine da(this)
     ! -- modules
@@ -176,7 +177,6 @@ subroutine da(this)
     class(NumericalPackageType) :: this !< NumericalPackageType object
     !
     ! -- deallocate
-    call mem_deallocate(this%input_mempath, 'INPUT_MEMPATH', this%memoryPath)
     call mem_deallocate(this%input_fname, 'INPUT_FNAME', this%memoryPath)
     call mem_deallocate(this%package_type, 'PACKAGE_TYPE', this%memoryPath)
     call mem_deallocate(this%id)
@@ -189,18 +189,15 @@ subroutine da(this)
     call mem_deallocate(this%ipakcb)
     call mem_deallocate(this%ionper)
     call mem_deallocate(this%lastonper)
-    !
-    ! -- return
-    return
   end subroutine da
 
   !> @ brief Check ionper
-    !!
-    !!  Generic method to read and check ionperiod, which is used to determine
-    !!  if new period data should be read from the input file. The check of
-    !!  ionperiod also makes sure periods are increasing in subsequent period
-    !!  data blocks.
-    !!
+  !!
+  !!  Generic method to read and check ionperiod, which is used to determine
+  !!  if new period data should be read from the input file. The check of
+  !!  ionperiod also makes sure periods are increasing in subsequent period
+  !!  data blocks.
+  !!
   !<
   subroutine read_check_ionper(this)
     ! -- modules
@@ -221,15 +218,12 @@ subroutine read_check_ionper(this)
       call store_error(errmsg)
       call this%parser%StoreErrorUnit()
     end if
-    !
-    ! -- return
-    return
   end subroutine read_check_ionper
 
   !> @ brief Read griddata block for a package
-    !!
-    !!  Generic method to read data in the GRIDDATA block for a package.
-    !!
+  !!
+  !!  Generic method to read data in the GRIDDATA block for a package.
+  !!
   !<
   subroutine get_block_data(this, tags, lfound, varinames)
     ! -- modules
@@ -290,9 +284,6 @@ subroutine get_block_data(this, tags, lfound, varinames)
         call this%parser%StoreErrorUnit()
       end if
     end do
-    !
-    ! -- return
-    return
   end subroutine get_block_data
 
 end module NumericalPackageModule
diff --git a/src/Model/TransportModel.f90 b/src/Model/TransportModel.f90
deleted file mode 100644
index f37082cc3cb..00000000000
--- a/src/Model/TransportModel.f90
+++ /dev/null
@@ -1,25 +0,0 @@
-!> @brief This module contains the base transport model type
-!!
-!! This module contains the base class for transport models.
-!!
-!<
-
-module TransportModelModule
-  use KindModule, only: DP, I4B
-  use ConstantsModule, only: LENFTYPE
-  use SimVariablesModule, only: errmsg
-  use NumericalModelModule, only: NumericalModelType
-
-  implicit none
-
-  private
-
-  public :: TransportModelType
-
-  type, extends(NumericalModelType) :: TransportModelType
-
-  contains
-
-  end type TransportModelType
-
-end module TransportModelModule
diff --git a/src/Model/TransportModel/tsp1.f90 b/src/Model/TransportModel/tsp1.f90
new file mode 100644
index 00000000000..f1de33b333a
--- /dev/null
+++ b/src/Model/TransportModel/tsp1.f90
@@ -0,0 +1,879 @@
+!> @brief This module contains the base transport model type
+!!
+!! This module contains the base class for transport models.
+!!
+!<
+
+module TransportModelModule
+  use KindModule, only: DP, I4B
+  use VersionModule, only: write_listfile_header
+  use ConstantsModule, only: LENFTYPE, LINELENGTH, DZERO, LENPAKLOC, &
+                             LENMEMPATH, LENVARNAME
+  use SimVariablesModule, only: errmsg
+  use NumericalModelModule, only: NumericalModelType
+  use BndModule, only: BndType, GetBndFromList
+  use TspIcModule, only: TspIcType
+  use TspFmiModule, only: TspFmiType
+  use TspAdvModule, only: TspAdvType
+  use TspSsmModule, only: TspSsmType
+  use TspMvtModule, only: TspMvtType
+  use TspOcModule, only: TspOcType
+  use TspObsModule, only: TspObsType
+  use BudgetModule, only: BudgetType
+  use MatrixBaseModule
+
+  implicit none
+
+  private
+
+  public :: TransportModelType
+
+  type, extends(NumericalModelType) :: TransportModelType
+
+    ! Generalized transport package types common to either GWT or GWE
+    type(TspAdvType), pointer :: adv => null() !< advection package
+    type(TspFmiType), pointer :: fmi => null() !< flow model interface
+    type(TspIcType), pointer :: ic => null() !< initial conditions package
+    type(TspMvtType), pointer :: mvt => null() !< mover transport package
+    type(TspObsType), pointer :: obs => null() !< observation package
+    type(TspOcType), pointer :: oc => null() !< output control package
+    type(TspSsmType), pointer :: ssm => null() !< source sink mixing package
+    type(BudgetType), pointer :: budget => null() !< budget object
+    integer(I4B), pointer :: infmi => null() ! unit number FMI
+    integer(I4B), pointer :: inadv => null() !< unit number ADV
+    integer(I4B), pointer :: inic => null() !< unit number IC
+    integer(I4B), pointer :: inmvt => null() !< unit number MVT
+    integer(I4B), pointer :: inoc => null() !< unit number OC
+    integer(I4B), pointer :: inobs => null() !< unit number OBS
+
+    integer(I4B), pointer :: inssm => null() !< unit number SSM
+    real(DP), pointer :: eqnsclfac => null() !< constant factor by which all terms in the model's governing equation are scaled (divided) for formulation and solution
+    ! Labels that will be defined
+    character(len=LENVARNAME) :: tsptype = '' !< "solute" or "heat"
+    character(len=LENVARNAME) :: depvartype = '' !< "concentration" or "temperature"
+    character(len=LENVARNAME) :: depvarunit = '' !< "mass" or "energy"
+    character(len=LENVARNAME) :: depvarunitabbrev = '' !< "M" or "E"
+
+  contains
+
+    ! -- public
+    procedure, public :: tsp_cr
+    procedure, public :: tsp_df
+    procedure, public :: tsp_da
+    procedure, public :: tsp_ac
+    procedure, public :: tsp_mc
+    procedure, public :: tsp_ar
+    procedure, public :: tsp_rp
+    procedure, public :: tsp_ad
+    procedure, public :: tsp_fc
+    procedure, public :: tsp_cc
+    procedure, public :: tsp_cq
+    procedure, public :: tsp_bd
+    procedure, public :: tsp_ot
+    procedure, public :: allocate_tsp_scalars
+    procedure, public :: set_tsp_labels
+    procedure, public :: ftype_check
+    ! -- private
+    procedure, private :: tsp_ot_obs
+    procedure, private :: tsp_ot_flow
+    procedure, private :: tsp_ot_flowja
+    procedure, private :: tsp_ot_dv
+    procedure, private :: tsp_ot_bdsummary
+    procedure, private :: create_lstfile
+    procedure, private :: create_tsp_packages
+    procedure, private :: log_namfile_options
+
+  end type TransportModelType
+
+contains
+
+  !> @brief Create a new generalized transport model object
+  !!
+  !! Create a new transport model that will be further refined into GWT or GWE
+  !<
+  subroutine tsp_cr(this, filename, id, modelname, macronym, indis)
+    ! -- modules
+    use MemoryHelperModule, only: create_mem_path
+    use MemoryManagerExtModule, only: mem_set_value
+    use SimVariablesModule, only: idm_context
+    use GwfNamInputModule, only: GwfNamParamFoundType
+    use BudgetModule, only: budget_cr
+    ! -- dummy
+    class(TransportModelType) :: this
+    character(len=*), intent(in) :: filename
+    integer(I4B), intent(in) :: id
+    integer(I4B), intent(inout) :: indis
+    character(len=*), intent(in) :: modelname
+    character(len=*), intent(in) :: macronym
+    ! -- local
+    character(len=LENMEMPATH) :: input_mempath
+    character(len=LINELENGTH) :: lst_fname
+    type(GwfNamParamFoundType) :: found
+    !
+    ! -- Assign values
+    this%filename = filename
+    this%name = modelname
+    this%id = id
+    this%macronym = macronym
+    !
+    ! -- set input model namfile memory path
+    input_mempath = create_mem_path(modelname, 'NAM', idm_context)
+    !
+    ! -- copy option params from input context
+    call mem_set_value(lst_fname, 'LIST', input_mempath, found%list)
+    call mem_set_value(this%iprpak, 'PRINT_INPUT', input_mempath, &
+                       found%print_input)
+    call mem_set_value(this%iprflow, 'PRINT_FLOWS', input_mempath, &
+                       found%print_flows)
+    call mem_set_value(this%ipakcb, 'SAVE_FLOWS', input_mempath, found%save_flows)
+    !
+    ! -- create the list file
+    call this%create_lstfile(lst_fname, filename, found%list)
+    !
+    ! -- activate save_flows if found
+    if (found%save_flows) then
+      this%ipakcb = -1
+    end if
+    !
+    ! -- log set options
+    if (this%iout > 0) then
+      call this%log_namfile_options(found)
+    end if
+    !
+    ! -- Create utility objects
+    call budget_cr(this%budget, this%name)
+    !
+    ! -- create model packages
+    call this%create_tsp_packages(indis)
+    !
+    ! -- Return
+    return
+  end subroutine tsp_cr
+
+  !> @brief Generalized transport model define model
+  !!
+  !! This subroutine extended by either GWT or GWE.  This routine calls the
+  !! define (df) routines for each attached package and sets variables and
+  !! pointers.
+  !<
+  subroutine tsp_df(this)
+    ! -- dummy variables
+    class(TransportModelType) :: this
+    !
+    ! -- Return
+    return
+  end subroutine tsp_df
+
+  !> @brief Generalized transport model add connections
+  !!
+  !! This subroutine extended by either GWT or GWE.  This routine adds the
+  !! internal connections of this model to the sparse matrix
+  !<
+  subroutine tsp_ac(this, sparse)
+    ! -- modules
+    use SparseModule, only: sparsematrix
+    ! -- dummy variables
+    class(TransportModelType) :: this
+    type(sparsematrix), intent(inout) :: sparse
+    ! -- local
+    !
+    ! -- Return
+    return
+  end subroutine tsp_ac
+
+  !> @brief Generalized transport model map coefficients
+  !!
+  !! This subroutine extended by either GWT or GWE.  This routine maps the
+  !! positions of this models connections in the numerical solution coefficient
+  !! matrix.
+  !<
+  subroutine tsp_mc(this, matrix_sln)
+    ! -- dummy
+    class(TransportModelType) :: this
+    class(MatrixBaseType), pointer :: matrix_sln !< global system matrix
+    ! -- local
+    !
+    ! -- Return
+    return
+  end subroutine tsp_mc
+
+  !> @brief Generalized transport model allocate and read
+  !!
+  !! This subroutine extended by either GWT or GWE.  This routine calls
+  !! the allocate and reads (ar) routines of attached packages and allocates
+  !! memory for arrays required by the model object.
+  !<
+  subroutine tsp_ar(this)
+    ! -- dummy variables
+    class(TransportModelType) :: this
+    !
+    ! -- Return
+    return
+  end subroutine tsp_ar
+
+  !> @brief Generalized transport model read and prepare
+  !!
+  !! This subroutine extended by either GWT or GWE.  This routine calls
+  !! the read and prepare (rp) routines of attached packages.
+  !<
+  subroutine tsp_rp(this)
+    ! -- dummy variables
+    class(TransportModelType) :: this
+    !
+    ! -- Return
+    return
+  end subroutine tsp_rp
+
+  !> @brief Generalized transport model time step advance
+  !!
+  !! This subroutine extended by either GWT or GWE.  This routine calls
+  !! the advance time step (ad) routines of attached packages.
+  !<
+  subroutine tsp_ad(this)
+    ! -- dummy variables
+    class(TransportModelType) :: this
+    !
+    ! -- Return
+    return
+  end subroutine tsp_ad
+
+  !> @brief Generalized transport model fill coefficients
+  !!
+  !! This subroutine extended by either GWT or GWE.  This routine calls
+  !! the fill coefficients (fc) routines of attached packages.
+  !<
+  subroutine tsp_fc(this, kiter, matrix_sln, inwtflag)
+    ! -- dummy variables
+    class(TransportModelType) :: this
+    integer(I4B), intent(in) :: kiter
+    class(MatrixBaseType), pointer :: matrix_sln
+    integer(I4B), intent(in) :: inwtflag
+    !
+    ! -- Return
+    return
+  end subroutine tsp_fc
+
+  !> @brief Generalized transport model final convergence check
+  !!
+  !! This subroutine extended by either GWT or GWE.  This routine calls
+  !! the convergence check (cc) routines of attached packages.
+  !<
+  subroutine tsp_cc(this, innertot, kiter, iend, icnvgmod, cpak, ipak, dpak)
+    ! -- dummy
+    class(TransportModelType) :: this
+    integer(I4B), intent(in) :: innertot
+    integer(I4B), intent(in) :: kiter
+    integer(I4B), intent(in) :: iend
+    integer(I4B), intent(in) :: icnvgmod
+    character(len=LENPAKLOC), intent(inout) :: cpak
+    integer(I4B), intent(inout) :: ipak
+    real(DP), intent(inout) :: dpak
+    ! -- local
+    !
+    ! -- Return
+    return
+  end subroutine tsp_cc
+
+  !> @brief Generalized transport model calculate flows
+  !!
+  !! This subroutine extended by either GWT or GWE.  This routine calculates
+  !! intercell flows (flowja)
+  !<
+  subroutine tsp_cq(this, icnvg, isuppress_output)
+    ! -- dummy variables
+    class(TransportModelType) :: this
+    integer(I4B), intent(in) :: icnvg
+    integer(I4B), intent(in) :: isuppress_output
+    ! -- local
+    !
+    ! -- Return
+    return
+  end subroutine tsp_cq
+
+  !> @brief Generalized transport model budget
+  !!
+  !! This subroutine extended by either GWT or GWE. This routine calculates
+  !! package contributions to model budget
+  !<
+  subroutine tsp_bd(this, icnvg, isuppress_output)
+    ! -- dummy
+    class(TransportModelType) :: this
+    integer(I4B), intent(in) :: icnvg
+    integer(I4B), intent(in) :: isuppress_output
+    !
+    ! -- Return
+    return
+  end subroutine tsp_bd
+
+  !> @brief Generalized transport model output routine
+  !!
+  !! Generalized transport model output
+  !<
+  subroutine tsp_ot(this, inmst)
+    ! -- modules
+    use TdisModule, only: kstp, kper, tdis_ot, endofperiod
+    ! -- dummy
+    class(TransportModelType) :: this
+    integer(I4B), intent(in) :: inmst
+    ! -- local
+    integer(I4B) :: idvsave
+    integer(I4B) :: idvprint
+    integer(I4B) :: icbcfl
+    integer(I4B) :: icbcun
+    integer(I4B) :: ibudfl
+    integer(I4B) :: ipflag
+    ! -- formats
+    character(len=*), parameter :: fmtnocnvg = &
+      "(1X,/9X,'****FAILED TO MEET SOLVER CONVERGENCE CRITERIA IN TIME STEP ', &
+      &I0,' OF STRESS PERIOD ',I0,'****')"
+    !
+    ! -- Set write and print flags
+    idvsave = 0
+    idvprint = 0
+    icbcfl = 0
+    ibudfl = 0
+    if (this%oc%oc_save(trim(this%depvartype))) idvsave = 1
+    if (this%oc%oc_print(trim(this%depvartype))) idvprint = 1
+    if (this%oc%oc_save('BUDGET')) icbcfl = 1
+    if (this%oc%oc_print('BUDGET')) ibudfl = 1
+    icbcun = this%oc%oc_save_unit('BUDGET')
+    !
+    ! -- Override ibudfl and idvprint flags for nonconvergence
+    !    and end of period
+    ibudfl = this%oc%set_print_flag('BUDGET', this%icnvg, endofperiod)
+    idvprint = this%oc%set_print_flag(trim(this%depvartype), &
+                                      this%icnvg, endofperiod)
+    !
+    !   Calculate and save observations
+    call this%tsp_ot_obs()
+    !
+    !   Save and print flows
+    call this%tsp_ot_flow(icbcfl, ibudfl, icbcun, inmst)
+    !
+    !   Save and print dependent variables
+    call this%tsp_ot_dv(idvsave, idvprint, ipflag)
+    !
+    !   Print budget summaries
+    call this%tsp_ot_bdsummary(ibudfl, ipflag)
+    !
+    ! -- Timing Output; if any dependendent variables or budgets
+    !    are printed, then ipflag is set to 1.
+    if (ipflag == 1) call tdis_ot(this%iout)
+    !
+    ! -- Write non-convergence message
+    if (this%icnvg == 0) then
+      write (this%iout, fmtnocnvg) kstp, kper
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine tsp_ot
+
+  !> @brief Generalized transport model output routine
+  !!
+  !! Calculate and save observations
+  !<
+  subroutine tsp_ot_obs(this)
+    class(TransportModelType) :: this
+    class(BndType), pointer :: packobj
+    integer(I4B) :: ip
+    ! -- Calculate and save observations
+    call this%obs%obs_bd()
+    call this%obs%obs_ot()
+
+    ! -- Calculate and save package obserations
+    do ip = 1, this%bndlist%Count()
+      packobj => GetBndFromList(this%bndlist, ip)
+      call packobj%bnd_bd_obs()
+      call packobj%bnd_ot_obs()
+    end do
+
+  end subroutine tsp_ot_obs
+
+  !> @brief Generalized transport model output routine
+  !!
+  !! Save and print flows
+  !<
+  subroutine tsp_ot_flow(this, icbcfl, ibudfl, icbcun, inmst)
+    ! -- dummy
+    class(TransportModelType) :: this
+    integer(I4B), intent(in) :: icbcfl
+    integer(I4B), intent(in) :: ibudfl
+    integer(I4B), intent(in) :: icbcun
+    integer(I4B), intent(in) :: inmst
+    ! -- local
+    class(BndType), pointer :: packobj
+    integer(I4B) :: ip
+    !
+    ! -- Save TSP flows
+    call this%tsp_ot_flowja(this%nja, this%flowja, icbcfl, icbcun)
+    if (this%infmi > 0) call this%fmi%fmi_ot_flow(icbcfl, icbcun)
+    if (this%inssm > 0) then
+      call this%ssm%ssm_ot_flow(icbcfl=icbcfl, ibudfl=0, icbcun=icbcun)
+    end if
+    do ip = 1, this%bndlist%Count()
+      packobj => GetBndFromList(this%bndlist, ip)
+      call packobj%bnd_ot_model_flows(icbcfl=icbcfl, ibudfl=0, icbcun=icbcun)
+    end do
+
+    ! -- Save advanced package flows
+    do ip = 1, this%bndlist%Count()
+      packobj => GetBndFromList(this%bndlist, ip)
+      call packobj%bnd_ot_package_flows(icbcfl=icbcfl, ibudfl=0)
+    end do
+    if (this%inmvt > 0) then
+      call this%mvt%mvt_ot_saveflow(icbcfl, ibudfl)
+    end if
+
+    ! -- Print Model (GWT or GWE) flows
+    ! no need to print flowja
+    ! no need to print mst
+    ! no need to print fmi
+    if (this%inssm > 0) then
+      call this%ssm%ssm_ot_flow(icbcfl=icbcfl, ibudfl=ibudfl, icbcun=0)
+    end if
+    do ip = 1, this%bndlist%Count()
+      packobj => GetBndFromList(this%bndlist, ip)
+      call packobj%bnd_ot_model_flows(icbcfl=icbcfl, ibudfl=ibudfl, icbcun=0)
+    end do
+
+    ! -- Print advanced package flows
+    do ip = 1, this%bndlist%Count()
+      packobj => GetBndFromList(this%bndlist, ip)
+      call packobj%bnd_ot_package_flows(icbcfl=0, ibudfl=ibudfl)
+    end do
+    if (this%inmvt > 0) then
+      call this%mvt%mvt_ot_printflow(icbcfl, ibudfl)
+    end if
+
+  end subroutine tsp_ot_flow
+
+  !> @brief Generalized transport model output routine
+  !!
+  !! Write intercell flows for the transport model
+  !<
+  subroutine tsp_ot_flowja(this, nja, flowja, icbcfl, icbcun)
+    ! -- dummy
+    class(TransportModelType) :: this
+    integer(I4B), intent(in) :: nja
+    real(DP), dimension(nja), intent(in) :: flowja
+    integer(I4B), intent(in) :: icbcfl
+    integer(I4B), intent(in) :: icbcun
+    ! -- local
+    integer(I4B) :: ibinun
+    ! -- formats
+    !
+    ! -- Set unit number for binary output
+    if (this%ipakcb < 0) then
+      ibinun = icbcun
+    elseif (this%ipakcb == 0) then
+      ibinun = 0
+    else
+      ibinun = this%ipakcb
+    end if
+    if (icbcfl == 0) ibinun = 0
+    !
+    ! -- Write the face flows if requested
+    if (ibinun /= 0) then
+      call this%dis%record_connection_array(flowja, ibinun, this%iout)
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine tsp_ot_flowja
+
+  !> @brief Generalized tranpsort model output routine
+  !!
+  !! Loop through attached packages saving and printing dependent variables
+  !<
+  subroutine tsp_ot_dv(this, idvsave, idvprint, ipflag)
+    class(TransportModelType) :: this
+    integer(I4B), intent(in) :: idvsave
+    integer(I4B), intent(in) :: idvprint
+    integer(I4B), intent(inout) :: ipflag
+    class(BndType), pointer :: packobj
+    integer(I4B) :: ip
+    !
+    ! -- Print advanced package dependent variables
+    do ip = 1, this%bndlist%Count()
+      packobj => GetBndFromList(this%bndlist, ip)
+      call packobj%bnd_ot_dv(idvsave, idvprint)
+    end do
+
+    ! -- save head and print head
+    call this%oc%oc_ot(ipflag)
+    !
+    ! -- Return
+    return
+  end subroutine tsp_ot_dv
+
+  !> @brief Generalized tranpsort model output budget summary
+  !!
+  !! Loop through attached packages and write budget summaries
+  !<
+  subroutine tsp_ot_bdsummary(this, ibudfl, ipflag)
+    use TdisModule, only: kstp, kper, totim
+    class(TransportModelType) :: this
+    integer(I4B), intent(in) :: ibudfl
+    integer(I4B), intent(inout) :: ipflag
+    class(BndType), pointer :: packobj
+    integer(I4B) :: ip
+    !
+    ! -- Package budget summary
+    do ip = 1, this%bndlist%Count()
+      packobj => GetBndFromList(this%bndlist, ip)
+      call packobj%bnd_ot_bdsummary(kstp, kper, this%iout, ibudfl)
+    end do
+
+    ! -- mover budget summary
+    if (this%inmvt > 0) then
+      call this%mvt%mvt_ot_bdsummary(ibudfl)
+    end if
+
+    ! -- model budget summary
+    if (ibudfl /= 0) then
+      ipflag = 1
+      call this%budget%budget_ot(kstp, kper, this%iout)
+    end if
+
+    ! -- Write to budget csv
+    call this%budget%writecsv(totim)
+    !
+    ! -- Return
+    return
+  end subroutine tsp_ot_bdsummary
+
+  !> @brief Allocate scalar variables for transport model
+  !!
+  !!  Method to allocate memory for non-allocatable members.
+  !<
+  subroutine allocate_tsp_scalars(this, modelname)
+    ! -- modules
+    use MemoryManagerModule, only: mem_allocate
+    ! -- dummy
+    class(TransportModelType) :: this
+    character(len=*), intent(in) :: modelname
+    !
+    ! -- allocate members from (grand)parent class
+    call this%NumericalModelType%allocate_scalars(modelname)
+    !
+    ! -- allocate members that are part of model class
+    call mem_allocate(this%inic, 'INIC', this%memoryPath)
+    call mem_allocate(this%infmi, 'INFMI', this%memoryPath)
+    call mem_allocate(this%inmvt, 'INMVT', this%memoryPath)
+    call mem_allocate(this%inadv, 'INADV', this%memoryPath)
+    call mem_allocate(this%inssm, 'INSSM', this%memoryPath)
+    call mem_allocate(this%inoc, 'INOC ', this%memoryPath)
+    call mem_allocate(this%inobs, 'INOBS', this%memoryPath)
+    call mem_allocate(this%eqnsclfac, 'EQNSCLFAC', this%memoryPath)
+    !
+    this%inic = 0
+    this%infmi = 0
+    this%inmvt = 0
+    this%inadv = 0
+    this%inssm = 0
+    this%inoc = 0
+    this%inobs = 0
+    this%eqnsclfac = DZERO
+    !
+    ! -- Return
+    return
+  end subroutine allocate_tsp_scalars
+
+  !> @brief Define the labels corresponding to the flavor of
+  !! transport model
+  !!
+  !! Set variable names according to type of transport model
+  !<
+  subroutine set_tsp_labels(this, tsptype, depvartype, depvarunit, &
+                            depvarunitabbrev)
+    class(TransportModelType) :: this
+    character(len=*), intent(in), pointer :: tsptype !< type of model, default is GWT (alternative is GWE)
+    character(len=*), intent(in) :: depvartype !< dependent variable type, default is "CONCENTRATION"
+    character(len=*), intent(in) :: depvarunit !< units of dependent variable for writing to list file
+    character(len=*), intent(in) :: depvarunitabbrev !< abbreviation of associated units
+    !
+    ! -- Set the model type
+    this%tsptype = tsptype
+    !
+    ! -- Set the type of dependent variable being solved for
+    this%depvartype = depvartype
+    !
+    ! -- Set the units associated with the dependent variable
+    this%depvarunit = depvarunit
+    !
+    ! -- Set the units abbreviation
+    this%depvarunitabbrev = depvarunitabbrev
+    !
+    ! -- Return
+    return
+  end subroutine set_tsp_labels
+
+  !> @brief Deallocate memory
+  !!
+  !! Deallocate memmory at conclusion of model run
+  !<
+  subroutine tsp_da(this)
+    ! -- modules
+    use MemoryManagerModule, only: mem_deallocate
+    ! -- dummy
+    class(TransportModelType) :: this
+    ! -- local
+    !
+    ! -- Scalars
+    call mem_deallocate(this%inic)
+    call mem_deallocate(this%infmi)
+    call mem_deallocate(this%inadv)
+    call mem_deallocate(this%inssm)
+    call mem_deallocate(this%inmvt)
+    call mem_deallocate(this%inoc)
+    call mem_deallocate(this%inobs)
+    call mem_deallocate(this%eqnsclfac)
+    !
+    ! -- Return
+    return
+  end subroutine tsp_da
+
+  !> @brief Generalized tranpsort model routine
+  !!
+  !! Check to make sure required input files have been specified
+  !<
+  subroutine ftype_check(this, indis, inmst)
+    ! -- modules
+    use ConstantsModule, only: LINELENGTH
+    use SimModule, only: store_error, count_errors, store_error_filename
+    ! -- dummy
+    class(TransportModelType) :: this
+    integer(I4B), intent(in) :: indis
+    integer(I4B), intent(in) :: inmst
+    ! -- local
+    character(len=LINELENGTH) :: errmsg
+! ------------------------------------------------------------------------------
+    !
+    ! -- Check for IC6, DIS(u), and MST. Stop if not present.
+    if (this%inic == 0) then
+      write (errmsg, '(a)') &
+        'Initial conditions (IC6) package not specified.'
+      call store_error(errmsg)
+    end if
+    if (indis == 0) then
+      write (errmsg, '(a)') &
+        'Discretization (DIS6 or DISU6) package not specified.'
+      call store_error(errmsg)
+    end if
+    if (inmst == 0) then
+      write (errmsg, '(a)') 'Mass storage and transfer (MST6) &
+        &package not specified.'
+      call store_error(errmsg)
+    end if
+    !
+    if (count_errors() > 0) then
+      write (errmsg, '(a)') 'Required package(s) not specified.'
+      call store_error(errmsg)
+      call store_error_filename(this%filename)
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine ftype_check
+
+  !> @brief Create listing output file
+  !<
+  subroutine create_lstfile(this, lst_fname, model_fname, defined)
+    ! -- modules
+    use KindModule, only: LGP
+    use InputOutputModule, only: openfile, getunit
+    ! -- dummy
+    class(TransportModelType) :: this
+    character(len=*), intent(inout) :: lst_fname
+    character(len=*), intent(in) :: model_fname
+    logical(LGP), intent(in) :: defined
+    ! -- local
+    integer(I4B) :: i, istart, istop
+    !
+    ! -- set list file name if not provided
+    if (.not. defined) then
+      !
+      ! -- initialize
+      lst_fname = ' '
+      istart = 0
+      istop = len_trim(model_fname)
+      !
+      ! -- identify '.' character position from back of string
+      do i = istop, 1, -1
+        if (model_fname(i:i) == '.') then
+          istart = i
+          exit
+        end if
+      end do
+      !
+      ! -- if not found start from string end
+      if (istart == 0) istart = istop + 1
+      !
+      ! -- set list file name
+      lst_fname = model_fname(1:istart)
+      istop = istart + 3
+      lst_fname(istart:istop) = '.lst'
+    end if
+    !
+    ! -- create the list file
+    this%iout = getunit()
+    call openfile(this%iout, 0, lst_fname, 'LIST', filstat_opt='REPLACE')
+    !
+    ! -- write list file header
+    call write_listfile_header(this%iout, 'GROUNDWATER TRANSPORT MODEL (GWT)')
+    !
+    ! -- Return
+    return
+  end subroutine create_lstfile
+
+  !> @brief Write model name file options to list file
+  !<
+  subroutine log_namfile_options(this, found)
+    use GwfNamInputModule, only: GwfNamParamFoundType
+    class(TransportModelType) :: this
+    type(GwfNamParamFoundType), intent(in) :: found
+    !
+    write (this%iout, '(1x,a)') 'NAMEFILE OPTIONS:'
+    !
+    if (found%newton) then
+      write (this%iout, '(4x,a)') &
+        'NEWTON-RAPHSON method enabled for the model.'
+      if (found%under_relaxation) then
+        write (this%iout, '(4x,a,a)') &
+          'NEWTON-RAPHSON UNDER-RELAXATION based on the bottom ', &
+          'elevation of the model will be applied to the model.'
+      end if
+    end if
+    !
+    if (found%print_input) then
+      write (this%iout, '(4x,a)') 'STRESS PACKAGE INPUT WILL BE PRINTED '// &
+        'FOR ALL MODEL STRESS PACKAGES'
+    end if
+    !
+    if (found%print_flows) then
+      write (this%iout, '(4x,a)') 'PACKAGE FLOWS WILL BE PRINTED '// &
+        'FOR ALL MODEL PACKAGES'
+    end if
+    !
+    if (found%save_flows) then
+      write (this%iout, '(4x,a)') &
+        'FLOWS WILL BE SAVED TO BUDGET FILE SPECIFIED IN OUTPUT CONTROL'
+    end if
+    !
+    write (this%iout, '(1x,a)') 'END NAMEFILE OPTIONS:'
+    !
+    ! -- Return
+    return
+  end subroutine log_namfile_options
+
+  !> @brief Source package info and begin to process
+  !<
+  subroutine create_tsp_packages(this, indis)
+    ! -- modules
+    use ConstantsModule, only: LINELENGTH, LENPACKAGENAME
+    use CharacterStringModule, only: CharacterStringType
+    use ArrayHandlersModule, only: expandarray
+    use MemoryManagerModule, only: mem_setptr
+    use MemoryHelperModule, only: create_mem_path
+    use SimVariablesModule, only: idm_context
+    use GwfDisModule, only: dis_cr
+    use GwfDisvModule, only: disv_cr
+    use GwfDisuModule, only: disu_cr
+    use TspIcModule, only: ic_cr
+    use TspFmiModule, only: fmi_cr
+    use TspAdvModule, only: adv_cr
+    use TspSsmModule, only: ssm_cr
+    use TspMvtModule, only: mvt_cr
+    use TspOcModule, only: oc_cr
+    use TspObsModule, only: tsp_obs_cr
+    ! -- dummy
+    class(TransportModelType) :: this
+    integer(I4B), intent(inout) :: indis ! DIS enabled flag
+    ! -- local
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: pkgtypes => null()
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: pkgnames => null()
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: mempaths => null()
+    integer(I4B), dimension(:), contiguous, &
+      pointer :: inunits => null()
+    character(len=LENMEMPATH) :: model_mempath
+    character(len=LENFTYPE) :: pkgtype
+    character(len=LENPACKAGENAME) :: pkgname
+    character(len=LENMEMPATH) :: mempath
+    integer(I4B), pointer :: inunit
+    integer(I4B) :: n
+    character(len=LENMEMPATH) :: mempathic = ''
+    !
+    ! -- Initialize
+    indis = 0
+    !
+    ! -- set input memory paths, input/model and input/model/namfile
+    model_mempath = create_mem_path(component=this%name, context=idm_context)
+    !
+    ! -- set pointers to model path package info
+    call mem_setptr(pkgtypes, 'PKGTYPES', model_mempath)
+    call mem_setptr(pkgnames, 'PKGNAMES', model_mempath)
+    call mem_setptr(mempaths, 'MEMPATHS', model_mempath)
+    call mem_setptr(inunits, 'INUNITS', model_mempath)
+    !
+    do n = 1, size(pkgtypes)
+      !
+      ! attributes for this input package
+      pkgtype = pkgtypes(n)
+      pkgname = pkgnames(n)
+      mempath = mempaths(n)
+      inunit => inunits(n)
+      !
+      ! -- create dis package as it is a prerequisite for other packages
+      select case (pkgtype)
+      case ('DIS6')
+        indis = 1
+        call dis_cr(this%dis, this%name, mempath, indis, this%iout)
+      case ('DISV6')
+        indis = 1
+        call disv_cr(this%dis, this%name, mempath, indis, this%iout)
+      case ('DISU6')
+        indis = 1
+        call disu_cr(this%dis, this%name, mempath, indis, this%iout)
+      case ('IC6')
+        this%inic = 1
+        mempathic = mempath
+      case ('FMI6')
+        this%infmi = inunit
+      case ('MVT6')
+        this%inmvt = inunit
+      case ('ADV6')
+        this%inadv = inunit
+      case ('SSM6')
+        this%inssm = inunit
+      case ('OC6')
+        this%inoc = inunit
+      case ('OBS6')
+        this%inobs = inunit
+        !case default
+        ! TODO
+      end select
+    end do
+    !
+    ! -- Create packages that are tied directly to model
+    call ic_cr(this%ic, this%name, mempathic, this%inic, this%iout, this%dis, &
+               this%depvartype)
+    call fmi_cr(this%fmi, this%name, this%infmi, this%iout, this%eqnsclfac, &
+                this%depvartype)
+    call adv_cr(this%adv, this%name, this%inadv, this%iout, this%fmi, &
+                this%eqnsclfac)
+    call ssm_cr(this%ssm, this%name, this%inssm, this%iout, this%fmi, &
+                this%eqnsclfac, this%depvartype)
+    call mvt_cr(this%mvt, this%name, this%inmvt, this%iout, this%fmi, &
+                this%eqnsclfac)
+    call oc_cr(this%oc, this%name, this%inoc, this%iout)
+    call tsp_obs_cr(this%obs, this%inobs)
+    !
+    ! -- Return
+    return
+  end subroutine create_tsp_packages
+
+end module TransportModelModule
diff --git a/src/Model/GroundWaterTransport/gwt1adv1.f90 b/src/Model/TransportModel/tsp1adv1.f90
similarity index 70%
rename from src/Model/GroundWaterTransport/gwt1adv1.f90
rename to src/Model/TransportModel/tsp1adv1.f90
index 0e9f4bdb487..f08d61351ca 100644
--- a/src/Model/GroundWaterTransport/gwt1adv1.f90
+++ b/src/Model/TransportModel/tsp1adv1.f90
@@ -1,23 +1,24 @@
-module GwtAdvModule
+module TspAdvModule
 
   use KindModule, only: DP, I4B
   use ConstantsModule, only: DONE, DZERO, DHALF, DTWO
   use NumericalPackageModule, only: NumericalPackageType
   use BaseDisModule, only: DisBaseType
-  use GwtFmiModule, only: GwtFmiType
-  use GwtAdvOptionsModule, only: GwtAdvOptionsType
+  use TspFmiModule, only: TspFmiType
+  use TspAdvOptionsModule, only: TspAdvOptionsType
   use MatrixBaseModule
 
   implicit none
   private
-  public :: GwtAdvType
+  public :: TspAdvType
   public :: adv_cr
 
-  type, extends(NumericalPackageType) :: GwtAdvType
+  type, extends(NumericalPackageType) :: TspAdvType
 
     integer(I4B), pointer :: iadvwt => null() !< advection scheme (0 up, 1 central, 2 tvd)
     integer(I4B), dimension(:), pointer, contiguous :: ibound => null() !< pointer to model ibound
-    type(GwtFmiType), pointer :: fmi => null() !< pointer to fmi object
+    type(TspFmiType), pointer :: fmi => null() !< pointer to fmi object
+    real(DP), pointer :: eqnsclfac => null() !< governing equation scale factor; =1. for solute; =rhow*cpw for energy
 
   contains
 
@@ -34,24 +35,22 @@ module GwtAdvModule
     procedure :: adv_weight
     procedure :: advtvd
 
-  end type GwtAdvType
+  end type TspAdvType
 
 contains
 
-  subroutine adv_cr(advobj, name_model, inunit, iout, fmi)
-! ******************************************************************************
-! adv_cr -- Create a new ADV object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @ brief Create a new ADV object
+  !!
+  !!  Create a new ADV package
+  !<
+  subroutine adv_cr(advobj, name_model, inunit, iout, fmi, eqnsclfac)
     ! -- dummy
-    type(GwtAdvType), pointer :: advobj
+    type(TspAdvType), pointer :: advobj
     character(len=*), intent(in) :: name_model
     integer(I4B), intent(in) :: inunit
     integer(I4B), intent(in) :: iout
-    type(GwtFmiType), intent(in), target :: fmi
-! ------------------------------------------------------------------------------
+    type(TspFmiType), intent(in), target :: fmi
+    real(DP), intent(in), pointer :: eqnsclfac !< governing equation scale factor
     !
     ! -- Create the object
     allocate (advobj)
@@ -66,15 +65,21 @@ subroutine adv_cr(advobj, name_model, inunit, iout, fmi)
     advobj%inunit = inunit
     advobj%iout = iout
     advobj%fmi => fmi
+    advobj%eqnsclfac => eqnsclfac
     !
     ! -- Return
     return
   end subroutine adv_cr
 
+  !> @brief Define ADV object
+  !!
+  !! Define the ADV package
+  !<
   subroutine adv_df(this, adv_options)
-    class(GwtAdvType) :: this
-    type(GwtAdvOptionsType), optional, intent(in) :: adv_options !< the optional options, for when not constructing from file
-    ! local
+    ! -- dummy
+    class(TspAdvType) :: this
+    type(TspAdvOptionsType), optional, intent(in) :: adv_options !< the optional options, for when not constructing from file
+    ! -- local
     character(len=*), parameter :: fmtadv = &
       "(1x,/1x,'ADV-- ADVECTION PACKAGE, VERSION 1, 8/25/2017', &
       &' INPUT READ FROM UNIT ', i0, //)"
@@ -96,24 +101,23 @@ subroutine adv_df(this, adv_options)
       ! --set options from input arg
       this%iadvwt = adv_options%iAdvScheme
     end if
-
+    !
+    ! -- Return
+    return
   end subroutine adv_df
 
+  !> @brief Allocate and read method for package
+  !!
+  !!  Method to allocate and read static data for the ADV package.
+  !<
   subroutine adv_ar(this, dis, ibound)
-! ******************************************************************************
-! adv_ar -- Allocate and Read
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAdvType) :: this
+    class(TspAdvType) :: this
     class(DisBaseType), pointer, intent(in) :: dis
-    integer(I4B), dimension(:), pointer, contiguous :: ibound
+    integer(I4B), dimension(:), pointer, contiguous, intent(in) :: ibound
     ! -- local
     ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- adv pointers to arguments that were passed in
     this%dis => dis
@@ -123,16 +127,14 @@ subroutine adv_ar(this, dis, ibound)
     return
   end subroutine adv_ar
 
+  !> @brief  Fill coefficient method for ADV package
+  !!
+  !!  Method to calculate coefficients and fill amat and rhs.
+  !<
   subroutine adv_fc(this, nodes, matrix_sln, idxglo, cnew, rhs)
-! ******************************************************************************
-! adv_fc -- Calculate coefficients and fill amat and rhs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAdvType) :: this
+    class(TspAdvType) :: this
     integer, intent(in) :: nodes
     class(MatrixBaseType), pointer :: matrix_sln
     integer(I4B), intent(in), dimension(:) :: idxglo
@@ -141,7 +143,6 @@ subroutine adv_fc(this, nodes, matrix_sln, idxglo, cnew, rhs)
     ! -- local
     integer(I4B) :: n, m, idiag, ipos
     real(DP) :: omega, qnm
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate advection terms and add to solution rhs and hcof.  qnm
     !    is the volumetric flow rate and has dimensions of L^/T.
@@ -152,7 +153,7 @@ subroutine adv_fc(this, nodes, matrix_sln, idxglo, cnew, rhs)
         if (this%dis%con%mask(ipos) == 0) cycle
         m = this%dis%con%ja(ipos)
         if (this%ibound(m) == 0) cycle
-        qnm = this%fmi%gwfflowja(ipos)
+        qnm = this%fmi%gwfflowja(ipos) * this%eqnsclfac
         omega = this%adv_weight(this%iadvwt, ipos, n, m, qnm)
         call matrix_sln%add_value_pos(idxglo(ipos), qnm * (DONE - omega))
         call matrix_sln%add_value_pos(idxglo(idiag), qnm * omega)
@@ -171,23 +172,21 @@ subroutine adv_fc(this, nodes, matrix_sln, idxglo, cnew, rhs)
     return
   end subroutine adv_fc
 
+  !> @brief  Calculate TVD
+  !!
+  !! Use explicit scheme to calculate the advective component of transport.
+  !! TVD is an acronym for Total-Variation Diminishing
+  !<
   subroutine advtvd(this, n, cnew, rhs)
-! ******************************************************************************
-! advtvd -- Calculate TVD
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAdvType) :: this
+    class(TspAdvType) :: this
     integer(I4B), intent(in) :: n
     real(DP), dimension(:), intent(in) :: cnew
     real(DP), dimension(:), intent(inout) :: rhs
     ! -- local
     real(DP) :: qtvd
     integer(I4B) :: m, ipos
-! ------------------------------------------------------------------------------
     !
     ! -- Loop through each n connection.  This will
     do ipos = this%dis%con%ia(n) + 1, this%dis%con%ia(n + 1) - 1
@@ -204,19 +203,18 @@ subroutine advtvd(this, n, cnew, rhs)
     return
   end subroutine advtvd
 
+  !> @brief  Calculate TVD
+  !!
+  !! Use explicit scheme to calculate the advective component of transport.
+  !! TVD is an acronym for Total-Variation Diminishing
+  !<
   function advqtvd(this, n, m, iposnm, cnew) result(qtvd)
-! ******************************************************************************
-! advqtvd -- Calculate TVD
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DPREC
     ! -- return
     real(DP) :: qtvd
     ! -- dummy
-    class(GwtAdvType) :: this
+    class(TspAdvType) :: this
     integer(I4B), intent(in) :: n
     integer(I4B), intent(in) :: m
     integer(I4B), intent(in) :: iposnm
@@ -225,7 +223,6 @@ function advqtvd(this, n, m, iposnm, cnew) result(qtvd)
     integer(I4B) :: ipos, isympos, iup, idn, i2up, j
     real(DP) :: qnm, qmax, qupj, elupdn, elup2up
     real(DP) :: smooth, cdiff, alimiter
-! ------------------------------------------------------------------------------
     !
     ! -- intialize
     qtvd = DZERO
@@ -269,6 +266,7 @@ function advqtvd(this, n, m, iposnm, cnew) result(qtvd)
       if (smooth > DZERO) then
         alimiter = DTWO * smooth / (DONE + smooth)
         qtvd = DHALF * alimiter * qnm * (cnew(idn) - cnew(iup))
+        qtvd = qtvd * this%eqnsclfac
       end if
     end if
     !
@@ -276,23 +274,18 @@ function advqtvd(this, n, m, iposnm, cnew) result(qtvd)
     return
   end function advqtvd
 
+  !> @brief Calculate advection contribution to flowja
+  !<
   subroutine adv_cq(this, cnew, flowja)
-! ******************************************************************************
-! adv_cq -- Calculate advection contribution to flowja
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAdvType) :: this
+    class(TspAdvType) :: this
     real(DP), intent(in), dimension(:) :: cnew
     real(DP), intent(inout), dimension(:) :: flowja
     ! -- local
     integer(I4B) :: nodes
     integer(I4B) :: n, m, idiag, ipos
     real(DP) :: omega, qnm
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate advection and add to flowja. qnm is the volumetric flow
     !    rate and has dimensions of L^/T.
@@ -303,7 +296,7 @@ subroutine adv_cq(this, cnew, flowja)
       do ipos = this%dis%con%ia(n) + 1, this%dis%con%ia(n + 1) - 1
         m = this%dis%con%ja(ipos)
         if (this%ibound(m) == 0) cycle
-        qnm = this%fmi%gwfflowja(ipos)
+        qnm = this%fmi%gwfflowja(ipos) * this%eqnsclfac
         omega = this%adv_weight(this%iadvwt, ipos, n, m, qnm)
         flowja(ipos) = flowja(ipos) + qnm * omega * cnew(n) + &
                        qnm * (DONE - omega) * cnew(m)
@@ -317,22 +310,16 @@ subroutine adv_cq(this, cnew, flowja)
     return
   end subroutine adv_cq
 
+  !> @brief Add TVD contribution to flowja
   subroutine advtvd_bd(this, cnew, flowja)
-! ******************************************************************************
-! advtvd_bd -- Add TVD contribution to flowja
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAdvType) :: this
+    class(TspAdvType) :: this
     real(DP), dimension(:), intent(in) :: cnew
     real(DP), dimension(:), intent(inout) :: flowja
     ! -- local
     real(DP) :: qtvd, qnm
     integer(I4B) :: nodes, n, m, ipos
-! ------------------------------------------------------------------------------
     !
     nodes = this%dis%nodes
     do n = 1, nodes
@@ -351,18 +338,13 @@ subroutine advtvd_bd(this, cnew, flowja)
     return
   end subroutine advtvd_bd
 
+  !> @brief Deallocate memory
+  !<
   subroutine adv_da(this)
-! ******************************************************************************
-! adv_da -- Deallocate variables
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
-    class(GwtAdvType) :: this
-! ------------------------------------------------------------------------------
+    class(TspAdvType) :: this
     !
     ! -- Deallocate arrays if package was active
     if (this%inunit > 0) then
@@ -381,17 +363,14 @@ subroutine adv_da(this)
     return
   end subroutine adv_da
 
+  !> @brief Allocate scalars specific to the streamflow energy transport (SFE)
+  !! package.
+  !<
   subroutine allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate, mem_setptr
     ! -- dummy
-    class(GwtAdvType) :: this
+    class(TspAdvType) :: this
     ! -- local
 ! ------------------------------------------------------------------------------
     !
@@ -411,18 +390,16 @@ subroutine allocate_scalars(this)
     return
   end subroutine allocate_scalars
 
+  !> @brief Read options
+  !!
+  !! Read the options block
+  !<
   subroutine read_options(this)
-! ******************************************************************************
-! read_options -- Allocate and Read
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error
     ! -- dummy
-    class(GwtAdvType) :: this
+    class(TspAdvType) :: this
     ! -- local
     character(len=LINELENGTH) :: errmsg, keyword
     integer(I4B) :: ierr
@@ -430,7 +407,6 @@ subroutine read_options(this)
     ! -- formats
     character(len=*), parameter :: fmtiadvwt = &
       &"(4x,'ADVECTION WEIGHTING SCHEME HAS BEEN SET TO: ', a)"
-! ------------------------------------------------------------------------------
     !
     ! -- get options block
     call this%parser%GetBlock('OPTIONS', isfound, ierr, blockRequired=.false., &
@@ -478,17 +454,15 @@ subroutine read_options(this)
     return
   end subroutine read_options
 
+  !> @ brief Advection weight
+  !!
+  !! Calculate the advection weight
+  !<
   function adv_weight(this, iadvwt, ipos, n, m, qnm) result(omega)
-! ******************************************************************************
-! adv_weight -- calculate advection weight
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: omega
     ! -- dummy
-    class(GwtAdvType) :: this
+    class(TspAdvType) :: this
     integer, intent(in) :: iadvwt
     integer, intent(in) :: ipos
     integer, intent(in) :: n
@@ -524,4 +498,4 @@ function adv_weight(this, iadvwt, ipos, n, m, qnm) result(omega)
     return
   end function adv_weight
 
-end module GwtAdvModule
+end module TspAdvModule
diff --git a/src/Model/GroundWaterTransport/gwt1apt1.f90 b/src/Model/TransportModel/tsp1apt1.f90
similarity index 77%
rename from src/Model/GroundWaterTransport/gwt1apt1.f90
rename to src/Model/TransportModel/tsp1apt1.f90
index 6f50995ac4c..4d2bb855b0d 100644
--- a/src/Model/GroundWaterTransport/gwt1apt1.f90
+++ b/src/Model/TransportModel/tsp1apt1.f90
@@ -12,12 +12,12 @@
 ! FLOW-JA-FACE              idxbudfjf     FLOW-JA-FACE          cv2cv
 ! GWF (aux FLOW-AREA)       idxbudgwf     GWF                   cv2gwf
 ! STORAGE (aux VOLUME)      idxbudsto     none                  used for cv volumes
-! FROM-MVR                  idxbudfmvr    FROM-MVR              q * cext = this%qfrommvr(:)
+! FROM-MVR                  idxbudfmvr    FROM-MVR              q * cext = this%qfrommvr(:)   ! rhow*cpw is applied to various terms for heat transport
 ! TO-MVR                    idxbudtmvr    TO-MVR                q * cfeat
 
 ! -- generalized source/sink terms (except ET?)
 ! RAINFALL                  idxbudrain    RAINFALL              q * crain
-! EVAPORATION               idxbudevap    EVAPORATION           cfeat<cevap: q*cfeat, else: q*cevap
+! EVAPORATION               idxbudevap    EVAPORATION           cfeat<cevap: q*cfeat, else: q*cevap  ! latent heat may be applied for evaporative cooling
 ! RUNOFF                    idxbudroff    RUNOFF                q * croff
 ! EXT-INFLOW                idxbudiflw    EXT-INFLOW            q * ciflw
 ! WITHDRAWAL                idxbudwdrl    WITHDRAWAL            q * cfeat
@@ -33,41 +33,42 @@
 ! none                      none          CONSTANT              accumulate
 !
 !
-module GwtAptModule
+module TspAptModule
 
   use KindModule, only: DP, I4B, LGP
   use ConstantsModule, only: DZERO, DONE, DEP20, LENFTYPE, LINELENGTH, &
                              LENBOUNDNAME, LENPACKAGENAME, NAMEDBOUNDFLAG, &
                              DNODATA, TABLEFT, TABCENTER, TABRIGHT, &
                              TABSTRING, TABUCSTRING, TABINTEGER, TABREAL, &
-                             LENAUXNAME
+                             LENAUXNAME, LENVARNAME
   use SimModule, only: store_error, store_error_unit, count_errors
   use SimVariablesModule, only: errmsg
   use BndModule, only: BndType
-  use GwtFmiModule, only: GwtFmiType
+  use TspFmiModule, only: TspFmiType
   use BudgetObjectModule, only: BudgetObjectType, budgetobject_cr
   use BudgetTermModule, only: BudgetTermType
   use TableModule, only: TableType, table_cr
   use ObserveModule, only: ObserveType
-  use InputOutputModule, only: extract_idnum_or_bndname
+  use InputOutputModule, only: extract_idnum_or_bndname, str_pad_left
   use BaseDisModule, only: DisBaseType
   use MatrixBaseModule
 
   implicit none
 
-  public :: GwtAptType
+  public :: TspAptType
   public :: apt_process_obsID
   public :: apt_process_obsID12
 
   character(len=LENFTYPE) :: ftype = 'APT'
-  character(len=16) :: text = '             APT'
+  character(len=LENVARNAME) :: text = '             APT'
+  character(len=LENVARNAME) :: tsptype = 'GWT' !< to be removed once TSP refactor is further sorted out
 
-  type, extends(BndType) :: GwtAptType
+  type, extends(BndType) :: TspAptType
 
     character(len=LENPACKAGENAME) :: flowpackagename = '' !< name of corresponding flow package
     character(len=8), &
       dimension(:), pointer, contiguous :: status => null() !< active, inactive, constant
-    character(len=LENAUXNAME) :: cauxfpconc = '' !< name of aux column in flow package auxvar array for concentration
+    character(len=LENAUXNAME) :: cauxfpconc = '' !< name of aux column in flow package auxvar array for concentration (or temperature)
     integer(I4B), pointer :: iauxfpconc => null() !< column in flow package bound array to insert concs
     integer(I4B), pointer :: imatrows => null() !< if active, add new rows to matrix
     integer(I4B), pointer :: iprconc => null() !< print conc to listing file
@@ -76,7 +77,10 @@ module GwtAptModule
     integer(I4B), pointer :: ibudcsv => null() !< unit number for csv budget output file
     integer(I4B), pointer :: ncv => null() !< number of control volumes
     integer(I4B), pointer :: igwfaptpak => null() !< package number of corresponding this package
-    real(DP), dimension(:), pointer, contiguous :: strt => null() !< starting feature concentration
+    integer(I4B), pointer :: idxprepak => null() !< budget-object index that precedes package-specific budget objects
+    integer(I4B), pointer :: idxlastpak => null() !< budget-object index of last package-specific budget object
+    real(DP), dimension(:), pointer, contiguous :: strt => null() !< starting feature concentration (or temperature)
+    real(DP), dimension(:), pointer, contiguous :: rfeatthk => null() !< thickness of streambed/lakebed/filter-pack material through which thermal conduction occurs
     integer(I4B), dimension(:), pointer, contiguous :: idxlocnode => null() !< map position in global rhs and x array of pack entry
     integer(I4B), dimension(:), pointer, contiguous :: idxpakdiag => null() !< map diag position of feature in global amat
     integer(I4B), dimension(:), pointer, contiguous :: idxdglo => null() !< map position in global array of package diagonal row entries
@@ -86,16 +90,16 @@ module GwtAptModule
     integer(I4B), dimension(:), pointer, contiguous :: idxfjfdglo => null() !< map diagonal feature to feature in global amat
     integer(I4B), dimension(:), pointer, contiguous :: idxfjfoffdglo => null() !< map off diagonal feature to feature in global amat
     integer(I4B), dimension(:), pointer, contiguous :: iboundpak => null() !< package ibound
-    real(DP), dimension(:), pointer, contiguous :: xnewpak => null() !< feature concentration for current time step
-    real(DP), dimension(:), pointer, contiguous :: xoldpak => null() !< feature concentration from previous time step
+    real(DP), dimension(:), pointer, contiguous :: xnewpak => null() !< feature concentration (or temperature) for current time step
+    real(DP), dimension(:), pointer, contiguous :: xoldpak => null() !< feature concentration (or temperature) from previous time step
     real(DP), dimension(:), pointer, contiguous :: dbuff => null() !< temporary storage array
     character(len=LENBOUNDNAME), &
       dimension(:), pointer, contiguous :: featname => null()
-    real(DP), dimension(:), pointer, contiguous :: concfeat => null() !< concentration of the feature
+    real(DP), dimension(:), pointer, contiguous :: concfeat => null() !< concentration (or temperature) of the feature
     real(DP), dimension(:, :), pointer, contiguous :: lauxvar => null() !< auxiliary variable
-    type(GwtFmiType), pointer :: fmi => null() !< pointer to fmi object
-    real(DP), dimension(:), pointer, contiguous :: qsto => null() !< mass flux due to storage change
-    real(DP), dimension(:), pointer, contiguous :: ccterm => null() !< mass flux required to maintain constant concentration
+    type(TspFmiType), pointer :: fmi => null() !< pointer to fmi object
+    real(DP), dimension(:), pointer, contiguous :: qsto => null() !< mass (or energy) flux due to storage change
+    real(DP), dimension(:), pointer, contiguous :: ccterm => null() !< mass (or energy) flux required to maintain constant concentration (or temperature)
     integer(I4B), pointer :: idxbudfjf => null() !< index of flow ja face in flowbudptr
     integer(I4B), pointer :: idxbudgwf => null() !< index of gwf terms in flowbudptr
     integer(I4B), pointer :: idxbudsto => null() !< index of storage terms in flowbudptr
@@ -104,8 +108,12 @@ module GwtAptModule
     integer(I4B), pointer :: idxbudaux => null() !< index of auxiliary terms in flowbudptr
     integer(I4B), dimension(:), pointer, contiguous :: idxbudssm => null() !< flag that flowbudptr%buditem is a general solute source/sink
     integer(I4B), pointer :: nconcbudssm => null() !< number of concbudssm terms (columns)
-    real(DP), dimension(:, :), pointer, contiguous :: concbudssm => null() !< user specified concentrations for flow terms
-    real(DP), dimension(:), pointer, contiguous :: qmfrommvr => null() !< a mass flow coming from the mover that needs to be added
+    real(DP), dimension(:, :), pointer, contiguous :: concbudssm => null() !< user specified concentrations (or temperatures) for flow terms
+    real(DP), dimension(:), pointer, contiguous :: qmfrommvr => null() !< a mass or energy flow coming from the mover that needs to be added
+    real(DP), pointer :: eqnsclfac => null() !< governing equation scale factor; =1. for solute; =rhow*cpw for energy
+    character(len=LENVARNAME) :: depvartype = '' !< stores string identifying dependent variable type, depending on model type
+    character(len=LENVARNAME) :: depvarunit = '' !< "mass" or "energy"
+    character(len=LENVARNAME) :: depvarunitabbrev = '' !< "M" or "E"
     !
     ! -- pointer to flow package boundary
     type(BndType), pointer :: flowpackagebnd => null()
@@ -125,12 +133,12 @@ module GwtAptModule
     procedure :: bnd_ar => apt_ar
     procedure :: bnd_rp => apt_rp
     procedure :: bnd_ad => apt_ad
-    procedure :: bnd_cf => apt_cf
+    procedure :: bnd_reset => apt_reset
     procedure :: bnd_fc => apt_fc
-    procedure, private :: apt_fc_expanded
+    procedure, public :: apt_fc_expanded ! Made public for uze
     procedure :: pak_fc_expanded
     procedure, private :: apt_fc_nonexpanded
-    procedure, private :: apt_cfupdate
+    procedure, public :: apt_cfupdate ! Made public for uze
     procedure :: apt_check_valid
     procedure :: apt_set_stressperiod
     procedure :: pak_set_stressperiod
@@ -168,27 +176,24 @@ module GwtAptModule
     procedure :: pak_setup_budobj
     procedure :: apt_fill_budobj
     procedure :: pak_fill_budobj
-    procedure, private :: apt_stor_term
-    procedure, private :: apt_tmvr_term
-    procedure, private :: apt_fjf_term
+    procedure, public :: apt_stor_term
+    procedure, public :: apt_tmvr_term
+    procedure, public :: apt_fmvr_term ! Made public for uze
+    procedure, public :: apt_fjf_term ! Made public for uze
     procedure, private :: apt_copy2flowp
     procedure, private :: apt_setup_tableobj
 
-  end type GwtAptType
+  end type TspAptType
 
 contains
 
+  !> @brief Add package connection to matrix
+  !<
   subroutine apt_ac(this, moffset, sparse)
-! ******************************************************************************
-! bnd_ac -- Add package connection to matrix
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use MemoryManagerModule, only: mem_setptr
     use SparseModule, only: sparsematrix
     ! -- dummy
-    class(GwtAptType), intent(inout) :: this
+    class(TspAptType), intent(inout) :: this
     integer(I4B), intent(in) :: moffset
     type(sparsematrix), intent(inout) :: sparse
     ! -- local
@@ -196,7 +201,6 @@ subroutine apt_ac(this, moffset, sparse)
     integer(I4B) :: jj, jglo
     integer(I4B) :: nglo
     ! -- format
-! ------------------------------------------------------------------------------
     !
     ! -- Add package rows to sparse
     if (this%imatrows /= 0) then
@@ -229,28 +233,22 @@ subroutine apt_ac(this, moffset, sparse)
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_ac
 
+  !> @brief Advanced package transport map package connections to matrix
+  !<
   subroutine apt_mc(this, moffset, matrix_sln)
-! ******************************************************************************
-! apt_mc -- map package connection to matrix
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use SparseModule, only: sparsematrix
     ! -- dummy
-    class(GwtAptType), intent(inout) :: this
+    class(TspAptType), intent(inout) :: this
     integer(I4B), intent(in) :: moffset
     class(MatrixBaseType), pointer :: matrix_sln
     ! -- local
     integer(I4B) :: n, j, iglo, jglo
     integer(I4B) :: ipos
     ! -- format
-! ------------------------------------------------------------------------------
-    !
     !
     ! -- allocate memory for index arrays
     call this%apt_allocate_index_arrays()
@@ -299,20 +297,16 @@ subroutine apt_mc(this, moffset, matrix_sln)
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_mc
 
+  !> @brief Advanced package transport allocate and read (ar) routine
+  !<
   subroutine apt_ar(this)
-! ******************************************************************************
-! apt_ar -- Allocate and Read
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAptType), intent(inout) :: this
+    class(TspAptType), intent(inout) :: this
     ! -- local
     integer(I4B) :: j
     logical :: found
@@ -320,7 +314,6 @@ subroutine apt_ar(this)
     character(len=*), parameter :: fmtapt = &
       "(1x,/1x,'APT -- ADVANCED PACKAGE TRANSPORT, VERSION 1, 3/5/2020', &
       &' INPUT READ FROM UNIT ', i0, //)"
-! ------------------------------------------------------------------------------
     !
     ! -- Get obs setup
     call this%obs%obs_ar()
@@ -346,8 +339,8 @@ subroutine apt_ar(this)
     this%fmi%datp(this%igwfaptpak)%qmfrommvr => this%qmfrommvr
     !
     ! -- If there is an associated flow package and the user wishes to put
-    !    simulated concentrations into a aux variable column, then find
-    !    the column number.
+    !    simulated concentrations (or temperatures) into a aux variable
+    !    column, then find the column number.
     if (associated(this%flowpackagebnd)) then
       if (this%cauxfpconc /= '') then
         found = .false.
@@ -376,18 +369,14 @@ subroutine apt_ar(this)
     return
   end subroutine apt_ar
 
+  !> @brief Advanced package transport read and prepare (rp) routine
+  !!
+  !! This subroutine calls the attached packages' read and prepare routines.
+  !<
   subroutine apt_rp(this)
-! ******************************************************************************
-! apt_rp -- Read and Prepare
-! Subroutine: (1) read itmp
-!             (2) read new boundaries if itmp>0
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use TdisModule, only: kper, nper
     ! -- dummy
-    class(GwtAptType), intent(inout) :: this
+    class(TspAptType), intent(inout) :: this
     ! -- local
     integer(I4B) :: ierr
     integer(I4B) :: n
@@ -401,7 +390,6 @@ subroutine apt_rp(this)
       &"('Error.  Looking for BEGIN PERIOD iper.  Found ', a, ' instead.')"
     character(len=*), parameter :: fmtlsp = &
       &"(1X,/1X,'REUSING ',A,'S FROM LAST STRESS PERIOD')"
-! ------------------------------------------------------------------------------
     !
     ! -- set nbound to maxbound
     this%nbound = this%maxbound
@@ -498,22 +486,20 @@ subroutine apt_rp(this)
       this%nodelist(n) = igwfnode
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_rp
 
+  !> @brief Advanced package transport set stress period routine.
+  !!
+  !! Set a stress period attribute for an advanced transport package feature
+  !! (itemno) using keywords.
+  !<
   subroutine apt_set_stressperiod(this, itemno)
-! ******************************************************************************
-! apt_set_stressperiod -- Set a stress period attribute for feature (itemno)
-!                         using keywords.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- module
     use TimeSeriesManagerModule, only: read_value_or_time_series_adv
     ! -- dummy
-    class(GwtAptType), intent(inout) :: this
+    class(TspAptType), intent(inout) :: this
     integer(I4B), intent(in) :: itemno
     ! -- local
     character(len=LINELENGTH) :: text
@@ -525,11 +511,10 @@ subroutine apt_set_stressperiod(this, itemno)
     real(DP), pointer :: bndElem => null()
     logical :: found
     ! -- formats
-! ------------------------------------------------------------------------------
     !
-    ! -- Support these general options with apply to LKT, SFT, MWT, UZT
+    ! -- Support these general options in LKT, SFT, MWT, UZT
     ! STATUS <status>
-    ! CONCENTRATION <concentration>
+    ! CONCENTRATION <concentration> or TEMPERATURE <temperature>
     ! WITHDRAWAL <withdrawal>
     ! AUXILIARY <auxname> <auxval>
     !
@@ -554,7 +539,7 @@ subroutine apt_set_stressperiod(this, itemno)
           'Unknown '//trim(this%text)//' status keyword: ', text//'.'
         call store_error(errmsg)
       end if
-    case ('CONCENTRATION')
+    case ('CONCENTRATION', 'TEMPERATURE')
       ierr = this%apt_check_valid(itemno)
       if (ierr /= 0) then
         goto 999
@@ -564,7 +549,7 @@ subroutine apt_set_stressperiod(this, itemno)
       bndElem => this%concfeat(itemno)
       call read_value_or_time_series_adv(text, itemno, jj, bndElem, &
                                          this%packName, 'BND', this%tsManager, &
-                                         this%iprpak, 'CONCENTRATION')
+                                         this%iprpak, this%depvartype)
     case ('AUXILIARY')
       ierr = this%apt_check_valid(itemno)
       if (ierr /= 0) then
@@ -601,50 +586,46 @@ subroutine apt_set_stressperiod(this, itemno)
       call this%parser%StoreErrorUnit()
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_set_stressperiod
 
+  !> @brief Advanced package transport set stress period routine.
+  !!
+  !! Set a stress period attribute for an individual package. This routine
+  !! must be overridden.
+  !<
   subroutine pak_set_stressperiod(this, itemno, keyword, found)
-! ******************************************************************************
-! pak_set_stressperiod -- Set a stress period attribute for individual package.
-!   This must be overridden.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
-    class(GwtAptType), intent(inout) :: this
+    class(TspAptType), intent(inout) :: this
     integer(I4B), intent(in) :: itemno
     character(len=*), intent(in) :: keyword
     logical, intent(inout) :: found
     ! -- local
 
     ! -- formats
-! ------------------------------------------------------------------------------
     !
     ! -- this routine should never be called
     found = .false.
     call store_error('Program error: pak_set_stressperiod not implemented.', &
                      terminate=.TRUE.)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine pak_set_stressperiod
 
+  !> @brief Advanced package transport routine
+  !!
+  !! Determine if a valid feature number has been specified.
+  !<
   function apt_check_valid(this, itemno) result(ierr)
-! ******************************************************************************
-!  apt_check_valid -- Determine if a valid feature number has been
-!                     specified.
-! ******************************************************************************
     ! -- return
     integer(I4B) :: ierr
     ! -- dummy
-    class(GwtAptType), intent(inout) :: this
+    class(TspAptType), intent(inout) :: this
     integer(I4B), intent(in) :: itemno
     ! -- local
     ! -- formats
-! ------------------------------------------------------------------------------
     ierr = 0
     if (itemno < 1 .or. itemno > this%ncv) then
       write (errmsg, '(a,1x,i6,1x,a,1x,i6)') &
@@ -654,21 +635,18 @@ function apt_check_valid(this, itemno) result(ierr)
     end if
   end function apt_check_valid
 
+  !> @brief Advanced package transport routine
+  !!
+  !! Add package connections to matrix
+  !<
   subroutine apt_ad(this)
-! ******************************************************************************
-! apt_ad -- Add package connection to matrix
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SimVariablesModule, only: iFailedStepRetry
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     ! -- local
     integer(I4B) :: n
     integer(I4B) :: j, iaux
-! ------------------------------------------------------------------------------
     !
     ! -- Advance the time series
     call this%TsManager%ad()
@@ -685,8 +663,8 @@ subroutine apt_ad(this)
       end do
     end if
     !
-    ! -- copy xnew into xold and set xnewpak to specified concentration for
-    !    constant concentration features
+    ! -- copy xnew into xold and set xnewpak to specified concentration (or
+    !    temperature) for constant concentration/temperature features
     if (iFailedStepRetry == 0) then
       do n = 1, this%ncv
         this%xoldpak(n) = this%xnewpak(n)
@@ -713,53 +691,34 @@ subroutine apt_ad(this)
     !    "current" value.
     call this%obs%obs_ad()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_ad
 
-  !> @ brief Formulate the package hcof and rhs terms.
-  !!
-  !!  For the APT Package, the sole purpose here is to
-  !!  reset the qmfrommvr term.
-  !!
-  !<
-  subroutine apt_cf(this, reset_mover)
-    ! -- modules
-    class(GwtAptType) :: this !< GwtAptType object
-    logical(LGP), intent(in), optional :: reset_mover !< boolean for resetting mover
-    ! -- local
+  !> @brief Override bnd reset for custom mover logic
+  !< TODO_MJR: check this
+  subroutine apt_reset(this)
+    class(TspAptType) :: this !< GwtAptType object
+    ! local
     integer(I4B) :: i
-    logical :: lrm
-    !
-    ! -- reset qmfrommvr
-    lrm = .true.
-    if (present(reset_mover)) lrm = reset_mover
-    if (lrm) then
-      do i = 1, size(this%qmfrommvr)
-        this%qmfrommvr(i) = DZERO
-      end do
-    end if
     !
-    ! -- return
+    do i = 1, size(this%qmfrommvr)
+      this%qmfrommvr(i) = DZERO
+    end do
+    !
+    ! -- Return
     return
-  end subroutine apt_cf
+  end subroutine apt_reset
 
   subroutine apt_fc(this, rhs, ia, idxglo, matrix_sln)
-! ******************************************************************************
-! apt_fc
-! ****************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     real(DP), dimension(:), intent(inout) :: rhs
     integer(I4B), dimension(:), intent(in) :: ia
     integer(I4B), dimension(:), intent(in) :: idxglo
     class(MatrixBaseType), pointer :: matrix_sln
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- Call fc depending on whether or not a matrix is expanded or not
     if (this%imatrows == 0) then
@@ -772,26 +731,23 @@ subroutine apt_fc(this, rhs, ia, idxglo, matrix_sln)
     return
   end subroutine apt_fc
 
+  !> @brief Advanced package transport fill coefficient (fc) method
+  !!
+  !! Routine to formulate the nonexpanded matrix case in which feature
+  !! concentrations (or temperatures) are solved explicitly
+  !<
   subroutine apt_fc_nonexpanded(this, rhs, ia, idxglo, matrix_sln)
-! ******************************************************************************
-! apt_fc_nonexpanded -- formulate for the nonexpanded a matrix case in which
-!   feature concentrations are solved explicitly
-! ****************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     real(DP), dimension(:), intent(inout) :: rhs
     integer(I4B), dimension(:), intent(in) :: ia
     integer(I4B), dimension(:), intent(in) :: idxglo
     class(MatrixBaseType), pointer :: matrix_sln
     ! -- local
     integer(I4B) :: j, igwfnode, idiag
-! ------------------------------------------------------------------------------
     !
-    ! -- solve for concentration in the features
+    ! -- solve for concentration (or temperatures) in the features
     call this%apt_solve()
     !
     ! -- add hcof and rhs terms (from apt_solve) to the gwf matrix
@@ -807,17 +763,15 @@ subroutine apt_fc_nonexpanded(this, rhs, ia, idxglo, matrix_sln)
     return
   end subroutine apt_fc_nonexpanded
 
+  !> @brief Advanced package transport fill coefficient (fc) method
+  !!
+  !! Routine to formulate the expanded matrix case in which new rows are added
+  !! to the system of equations for each advanced package transport feature
+  !<
   subroutine apt_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
-! ******************************************************************************
-! apt_fc_expanded -- formulate for the expanded matrix case in which new
-!   rows are added to the system of equations for each feature
-! ****************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     real(DP), dimension(:), intent(inout) :: rhs
     integer(I4B), dimension(:), intent(in) :: ia
     integer(I4B), dimension(:), intent(in) :: idxglo
@@ -828,12 +782,11 @@ subroutine apt_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
     integer(I4B) :: iposd, iposoffd
     integer(I4B) :: ipossymd, ipossymoffd
     real(DP) :: cold
-    real(DP) :: qbnd
+    real(DP) :: qbnd, qbnd_scaled
     real(DP) :: omega
     real(DP) :: rrate
     real(DP) :: rhsval
     real(DP) :: hcofval
-! ------------------------------------------------------------------------------
     !
     ! -- call the specific method for the advanced transport package, such as
     !    what would be overridden by
@@ -842,7 +795,7 @@ subroutine apt_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
     !    specific to the package
     call this%pak_fc_expanded(rhs, ia, idxglo, matrix_sln)
     !
-    ! -- mass storage in features
+    ! -- mass (or energy) storage in features
     do n = 1, this%ncv
       cold = this%xoldpak(n)
       iloc = this%idxlocnode(n)
@@ -866,7 +819,7 @@ subroutine apt_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
     ! -- add from mover contribution
     if (this%idxbudfmvr /= 0) then
       do n = 1, this%ncv
-        rhsval = this%qmfrommvr(n)
+        rhsval = this%qmfrommvr(n) ! this will already be in terms of energy for heat transport
         iloc = this%idxlocnode(n)
         rhs(iloc) = rhs(iloc) - rhsval
       end do
@@ -883,18 +836,19 @@ subroutine apt_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
         qbnd = this%flowbudptr%budterm(this%idxbudgwf)%flow(j)
         omega = DZERO
         if (qbnd < DZERO) omega = DONE
+        qbnd_scaled = qbnd * this%eqnsclfac
         !
         ! -- add to apt row
         iposd = this%idxdglo(j)
         iposoffd = this%idxoffdglo(j)
-        call matrix_sln%add_value_pos(iposd, omega * qbnd)
-        call matrix_sln%add_value_pos(iposoffd, (DONE - omega) * qbnd)
+        call matrix_sln%add_value_pos(iposd, omega * qbnd_scaled)
+        call matrix_sln%add_value_pos(iposoffd, (DONE - omega) * qbnd_scaled)
         !
         ! -- add to gwf row for apt connection
         ipossymd = this%idxsymdglo(j)
         ipossymoffd = this%idxsymoffdglo(j)
-        call matrix_sln%add_value_pos(ipossymd, -(DONE - omega) * qbnd)
-        call matrix_sln%add_value_pos(ipossymoffd, -omega * qbnd)
+        call matrix_sln%add_value_pos(ipossymd, -(DONE - omega) * qbnd_scaled)
+        call matrix_sln%add_value_pos(ipossymoffd, -omega * qbnd_scaled)
       end if
     end do
     !
@@ -909,10 +863,11 @@ subroutine apt_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
         else
           omega = DZERO
         end if
+        qbnd_scaled = qbnd * this%eqnsclfac
         iposd = this%idxfjfdglo(j)
         iposoffd = this%idxfjfoffdglo(j)
-        call matrix_sln%add_value_pos(iposd, omega * qbnd)
-        call matrix_sln%add_value_pos(iposoffd, (DONE - omega) * qbnd)
+        call matrix_sln%add_value_pos(iposd, omega * qbnd_scaled)
+        call matrix_sln%add_value_pos(iposoffd, (DONE - omega) * qbnd_scaled)
       end do
     end if
     !
@@ -920,23 +875,20 @@ subroutine apt_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
     return
   end subroutine apt_fc_expanded
 
+  !> @brief Advanced package transport fill coefficient (fc) method
+  !!
+  !! Routine to allow a subclass advanced transport package to inject
+  !! terms into the matrix assembly.  This method must be overridden.
+  !<
   subroutine pak_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
-! ******************************************************************************
-! pak_fc_expanded -- allow a subclass advanced transport package to inject
-!   terms into the matrix assembly.  This method must be overridden.
-! ****************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     real(DP), dimension(:), intent(inout) :: rhs
     integer(I4B), dimension(:), intent(in) :: ia
     integer(I4B), dimension(:), intent(in) :: idxglo
     class(MatrixBaseType), pointer :: matrix_sln
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- this routine should never be called
     call store_error('Program error: pak_fc_expanded not implemented.', &
@@ -946,25 +898,23 @@ subroutine pak_fc_expanded(this, rhs, ia, idxglo, matrix_sln)
     return
   end subroutine pak_fc_expanded
 
+  !> @brief Advanced package transport routine
+  !!
+  !! Calculate advanced package transport hcof and rhs so transport budget is
+  !! calculated.
+  !<
   subroutine apt_cfupdate(this)
-! ******************************************************************************
-! apt_cfupdate -- calculate package hcof and rhs so gwt budget is calculated
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     ! -- local
     integer(I4B) :: j, n
     real(DP) :: qbnd
     real(DP) :: omega
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate hcof and rhs terms so GWF exchanges are calculated correctly
     ! -- go through each apt-gwf connection and calculate
-    !    rhs and hcof terms for gwt matrix rows
+    !    rhs and hcof terms for gwt/gwe matrix rows
     do j = 1, this%flowbudptr%budterm(this%idxbudgwf)%nlist
       n = this%flowbudptr%budterm(this%idxbudgwf)%id1(j)
       this%hcof(j) = DZERO
@@ -973,8 +923,8 @@ subroutine apt_cfupdate(this)
         qbnd = this%flowbudptr%budterm(this%idxbudgwf)%flow(j)
         omega = DZERO
         if (qbnd < DZERO) omega = DONE
-        this%hcof(j) = -(DONE - omega) * qbnd
-        this%rhs(j) = omega * qbnd * this%xnewpak(n)
+        this%hcof(j) = -(DONE - omega) * qbnd * this%eqnsclfac
+        this%rhs(j) = omega * qbnd * this%xnewpak(n) * this%eqnsclfac
       end if
     end do
     !
@@ -982,26 +932,23 @@ subroutine apt_cfupdate(this)
     return
   end subroutine apt_cfupdate
 
+  !> @brief Advanced package transport calculate flows (cq) routine
+  !!
+  !! Calculate flows for the advanced package transport feature
+  !<
   subroutine apt_cq(this, x, flowja, iadv)
-! ******************************************************************************
-! apt_cq -- Calculate flows for the feature
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAptType), intent(inout) :: this
+    class(TspAptType), intent(inout) :: this
     real(DP), dimension(:), intent(in) :: x
     real(DP), dimension(:), contiguous, intent(inout) :: flowja
     integer(I4B), optional, intent(in) :: iadv
     ! -- local
     integer(I4B) :: n, n1, n2
     real(DP) :: rrate
-! ------------------------------------------------------------------------------
     !
-    ! -- Solve the feature concentrations again or update the feature hcof
-    !    and rhs terms
+    ! -- Solve the feature concentrations (or temperatures) again or update
+    !    the feature hcof and rhs terms
     if (this%imatrows == 0) then
       call this%apt_solve()
     else
@@ -1020,19 +967,21 @@ subroutine apt_cq(this, x, flowja, iadv)
       this%qsto(n) = rrate
     end do
     !
-    ! -- Copy concentrations into the flow package auxiliary variable
+    ! -- Copy concentrations (or temperatures) into the flow package auxiliary variable
     call this%apt_copy2flowp()
     !
     ! -- fill the budget object
-    call this%apt_fill_budobj(x)
+    call this%apt_fill_budobj(x, flowja)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_cq
 
+  !> @brief Save advanced package flows routine
+  !<
   subroutine apt_ot_package_flows(this, icbcfl, ibudfl)
     use TdisModule, only: kstp, kper, delt, pertim, totim
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     integer(I4B), intent(in) :: icbcfl
     integer(I4B), intent(in) :: ibudfl
     integer(I4B) :: ibinun
@@ -1052,19 +1001,26 @@ subroutine apt_ot_package_flows(this, icbcfl, ibudfl)
     if (ibudfl /= 0 .and. this%iprflow /= 0) then
       call this%budobj%write_flowtable(this%dis, kstp, kper)
     end if
-
+    !
+    ! -- Return
+    return
   end subroutine apt_ot_package_flows
 
   subroutine apt_ot_dv(this, idvsave, idvprint)
+    ! -- modules
+    use ConstantsModule, only: LENBUDTXT
     use TdisModule, only: kstp, kper, pertim, totim
-    use ConstantsModule, only: DHNOFLO, DHDRY
+    use ConstantsModule, only: DHNOFLO, DHDRY, LENBUDTXT
     use InputOutputModule, only: ulasav
-    class(GwtAptType) :: this
+    ! -- dummy
+    class(TspAptType) :: this
     integer(I4B), intent(in) :: idvsave
     integer(I4B), intent(in) :: idvprint
+    ! -- local
     integer(I4B) :: ibinun
     integer(I4B) :: n
     real(DP) :: c
+    character(len=LENBUDTXT) :: text
     !
     ! -- set unit number for binary dependent variable output
     ibinun = 0
@@ -1082,7 +1038,8 @@ subroutine apt_ot_dv(this, idvsave, idvprint)
         end if
         this%dbuff(n) = c
       end do
-      call ulasav(this%dbuff, '   CONCENTRATION', kstp, kper, pertim, totim, &
+      write (text, '(a)') str_pad_left(this%depvartype, LENVARNAME)
+      call ulasav(this%dbuff, text, kstp, kper, pertim, totim, &
                   this%ncv, 1, 1, ibinun)
     end if
     !
@@ -1101,14 +1058,18 @@ subroutine apt_ot_dv(this, idvsave, idvprint)
         call this%dvtab%add_term(this%xnewpak(n))
       end do
     end if
-
+    !
+    ! -- Return
+    return
   end subroutine apt_ot_dv
 
+  !> @brief Print advanced package transport dependent variables
+  !<
   subroutine apt_ot_bdsummary(this, kstp, kper, iout, ibudfl)
     ! -- module
     use TdisModule, only: totim
     ! -- dummy
-    class(GwtAptType) :: this !< GwtAptType object
+    class(TspAptType) :: this !< TspAptType object
     integer(I4B), intent(in) :: kstp !< time step number
     integer(I4B), intent(in) :: kper !< period number
     integer(I4B), intent(in) :: iout !< flag and unit number for the model listing file
@@ -1116,20 +1077,19 @@ subroutine apt_ot_bdsummary(this, kstp, kper, iout, ibudfl)
     !
     call this%budobj%write_budtable(kstp, kper, iout, ibudfl, totim)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_ot_bdsummary
 
   !> @ brief Allocate scalars
   !!
-  !! Allocate scalar variables for this package
-  !!
+  !! Allocate scalar variables for an advanced package
   !<
   subroutine allocate_scalars(this)
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     ! -- local
     !
     ! -- allocate scalars in NumericalPackageType
@@ -1151,6 +1111,8 @@ subroutine allocate_scalars(this)
     call mem_allocate(this%idxbudfmvr, 'IDXBUDFMVR', this%memoryPath)
     call mem_allocate(this%idxbudaux, 'IDXBUDAUX', this%memoryPath)
     call mem_allocate(this%nconcbudssm, 'NCONCBUDSSM', this%memoryPath)
+    call mem_allocate(this%idxprepak, 'IDXPREPAK', this%memoryPath)
+    call mem_allocate(this%idxlastpak, 'IDXLASTPAK', this%memoryPath)
     !
     ! -- Initialize
     this%iauxfpconc = 0
@@ -1168,6 +1130,8 @@ subroutine allocate_scalars(this)
     this%idxbudfmvr = 0
     this%idxbudaux = 0
     this%nconcbudssm = 0
+    this%idxprepak = 0
+    this%idxlastpak = 0
     !
     ! -- set this package as causing asymmetric matrix terms
     this%iasym = 1
@@ -1178,18 +1142,16 @@ end subroutine allocate_scalars
 
   !> @ brief Allocate index arrays
   !!
-  !! Allocate arrays that map to locations in the
-  !! numerical solution
-  !!
+  !! Allocate arrays that map to locations in the numerical solution
   !<
   subroutine apt_allocate_index_arrays(this)
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
-    class(GwtAptType), intent(inout) :: this
+    class(TspAptType), intent(inout) :: this
     ! -- local
     integer(I4B) :: n
-
+    !
     if (this%imatrows /= 0) then
       !
       ! -- count number of flow-ja-face connections
@@ -1233,19 +1195,20 @@ subroutine apt_allocate_index_arrays(this)
       call mem_allocate(this%idxfjfoffdglo, 0, 'IDXFJFOFFDGLO', &
                         this%memoryPath)
     end if
+    !
+    ! -- Return
     return
   end subroutine apt_allocate_index_arrays
 
   !> @ brief Allocate arrays
   !!
-  !! Allocate package arrays
-  !!
+  !! Allocate advanced package transport arrays
   !<
   subroutine apt_allocate_arrays(this)
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
-    class(GwtAptType), intent(inout) :: this
+    class(TspAptType), intent(inout) :: this
     ! -- local
     integer(I4B) :: n
     !
@@ -1278,7 +1241,7 @@ subroutine apt_allocate_arrays(this)
     call mem_allocate(this%concbudssm, this%nconcbudssm, this%ncv, &
                       'CONCBUDSSM', this%memoryPath)
     !
-    ! -- mass added from the mover transport package
+    ! -- mass (or energy) added from the mover transport package
     call mem_allocate(this%qmfrommvr, this%ncv, 'QMFROMMVR', this%memoryPath)
     !
     ! -- initialize arrays
@@ -1298,13 +1261,12 @@ end subroutine apt_allocate_arrays
   !> @ brief Deallocate memory
   !!
   !! Deallocate memory associated with this package
-  !!
   !<
   subroutine apt_da(this)
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     ! -- local
     !
     ! -- deallocate arrays
@@ -1363,6 +1325,8 @@ subroutine apt_da(this)
     call mem_deallocate(this%idxbudaux)
     call mem_deallocate(this%idxbudssm)
     call mem_deallocate(this%nconcbudssm)
+    call mem_deallocate(this%idxprepak)
+    call mem_deallocate(this%idxlastpak)
     !
     ! -- deallocate scalars in NumericalPackageType
     call this%BndType%bnd_da()
@@ -1371,19 +1335,14 @@ subroutine apt_da(this)
     return
   end subroutine apt_da
 
+  !> @brief Find corresponding advanced package transport package
+  !<
   subroutine find_apt_package(this)
-! ******************************************************************************
-! find corresponding flow package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- this routine should never be called
     call store_error('Program error: pak_solve not implemented.', &
@@ -1393,20 +1352,16 @@ subroutine find_apt_package(this)
     return
   end subroutine find_apt_package
 
+  !> @brief Set options specific to the TspAptType
+  !!
+  !! This routine overrides BndType%bnd_options
+  !<
   subroutine apt_options(this, option, found)
-! ******************************************************************************
-! apt_options -- set options specific to GwtAptType
-!
-! apt_options overrides BndType%bnd_options
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use ConstantsModule, only: MAXCHARLEN, DZERO
     use OpenSpecModule, only: access, form
     use InputOutputModule, only: urword, getunit, openfile
     ! -- dummy
-    class(GwtAptType), intent(inout) :: this
+    class(TspAptType), intent(inout) :: this
     character(len=*), intent(inout) :: option
     logical, intent(inout) :: found
     ! -- local
@@ -1415,7 +1370,6 @@ subroutine apt_options(this, option, found)
     character(len=*), parameter :: fmtaptbin = &
       "(4x, a, 1x, a, 1x, ' WILL BE SAVED TO FILE: ', a, &
       &/4x, 'OPENED ON UNIT: ', I0)"
-! ------------------------------------------------------------------------------
     !
     found = .true.
     select case (option)
@@ -1439,11 +1393,12 @@ subroutine apt_options(this, option, found)
       write (this%iout, '(4x,a)') &
         trim(adjustl(this%text))// &
         ' WILL NOT ADD ADDITIONAL ROWS TO THE A MATRIX.'
-    case ('PRINT_CONCENTRATION')
+    case ('PRINT_CONCENTRATION', 'PRINT_TEMPERATURE')
       this%iprconc = 1
-      write (this%iout, '(4x,a)') trim(adjustl(this%text))// &
-        ' CONCENTRATIONS WILL BE PRINTED TO LISTING FILE.'
-    case ('CONCENTRATION')
+      write (this%iout, '(4x,a,1x,a,1x,a)') trim(adjustl(this%text))// &
+        trim(adjustl(this%depvartype))//'S WILL BE PRINTED TO LISTING &
+          &FILE.'
+    case ('CONCENTRATION', 'TEMPERATURE')
       call this%parser%GetStringCaps(keyword)
       if (keyword == 'FILEOUT') then
         call this%parser%GetString(fname)
@@ -1451,10 +1406,12 @@ subroutine apt_options(this, option, found)
         call openfile(this%iconcout, this%iout, fname, 'DATA(BINARY)', &
                       form, access, 'REPLACE')
         write (this%iout, fmtaptbin) &
-          trim(adjustl(this%text)), 'CONCENTRATION', trim(fname), this%iconcout
+          trim(adjustl(this%text)), trim(adjustl(this%depvartype)), &
+          trim(fname), this%iconcout
       else
-        call store_error('Optional CONCENTRATION keyword must &
-                         &be followed by FILEOUT')
+        write (errmsg, "('Optional', 1x, a, 1X, 'keyword must &
+                         &be followed by FILEOUT')") this%depvartype
+        call store_error(errmsg)
       end if
     case ('BUDGET')
       call this%parser%GetStringCaps(keyword)
@@ -1487,23 +1444,18 @@ subroutine apt_options(this, option, found)
       found = .false.
     end select
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_options
 
+  !> @brief Determine dimensions for this advanced package
+  !<
   subroutine apt_read_dimensions(this)
-! ******************************************************************************
-! apt_read_dimensions -- Determine dimensions for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
-    class(GwtAptType), intent(inout) :: this
+    class(TspAptType), intent(inout) :: this
     ! -- local
     integer(I4B) :: ierr
     ! -- format
-! ------------------------------------------------------------------------------
     !
     ! -- Set a pointer to the GWF LAK Package budobj
     if (this%flowpackagename == '') then
@@ -1561,22 +1513,18 @@ subroutine apt_read_dimensions(this)
     ! -- setup the conc table object
     call this%apt_setup_tableobj()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_read_dimensions
 
+  !> @brief Read feature information for this advanced package
+  !<
   subroutine apt_read_cvs(this)
-! ******************************************************************************
-! apt_read_cvs -- Read feature information for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     use TimeSeriesManagerModule, only: read_value_or_time_series_adv
     ! -- dummy
-    class(GwtAptType), intent(inout) :: this
+    class(TspAptType), intent(inout) :: this
     ! -- local
     character(len=LINELENGTH) :: text
     character(len=LENBOUNDNAME) :: bndName, bndNameTemp
@@ -1592,7 +1540,6 @@ subroutine apt_read_cvs(this)
     integer(I4B) :: nconn
     integer(I4B), dimension(:), pointer, contiguous :: nboundchk
     real(DP), pointer :: bndElem => null()
-! ------------------------------------------------------------------------------
     !
     ! -- initialize itmp
     itmp = 0
@@ -1655,13 +1602,13 @@ subroutine apt_read_cvs(this)
           call store_error(errmsg)
           cycle
         end if
-
+        !
         ! -- increment nboundchk
         nboundchk(n) = nboundchk(n) + 1
-
+        !
         ! -- strt
         this%strt(n) = this%parser%GetDouble()
-
+        !
         ! -- get aux data
         do iaux = 1, this%naux
           call this%parser%GetString(caux(iaux))
@@ -1691,7 +1638,7 @@ subroutine apt_read_cvs(this)
                                              this%tsManager, this%iprpak, &
                                              this%auxname(jj))
         end do
-
+        !
         nlak = nlak + 1
       end do
       !
@@ -1706,7 +1653,7 @@ subroutine apt_read_cvs(this)
           call store_error(errmsg)
         end if
       end do
-
+      !
       write (this%iout, '(1x,a)') &
         'END OF '//trim(adjustl(this%text))//' PACKAGEDATA'
     else
@@ -1726,74 +1673,30 @@ subroutine apt_read_cvs(this)
     ! -- deallocate local storage for nboundchk
     deallocate (nboundchk)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_read_cvs
 
+  !> @brief Read the initial parameters for an advanced package
+  !<
   subroutine apt_read_initial_attr(this)
-! ******************************************************************************
-! apt_read_initial_attr -- Read the initial parameters for this package
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use ConstantsModule, only: LINELENGTH
     use BudgetModule, only: budget_cr
     ! -- dummy
-    class(GwtAptType), intent(inout) :: this
+    class(TspAptType), intent(inout) :: this
     ! -- local
     !character(len=LINELENGTH) :: text
     integer(I4B) :: j, n
-    !integer(I4B) :: nn
-    !integer(I4B) :: idx
-    !real(DP) :: endtim
-    !real(DP) :: top
-    !real(DP) :: bot
-    !real(DP) :: k
-    !real(DP) :: area
-    !real(DP) :: length
-    !real(DP) :: s
-    !real(DP) :: dx
-    !real(DP) :: c
-    !real(DP) :: sa
-    !real(DP) :: wa
-    !real(DP) :: v
-    !real(DP) :: fact
-    !real(DP) :: c1
-    !real(DP) :: c2
-    !real(DP), allocatable, dimension(:) :: clb, caq
-    !character (len=14) :: cbedleak
-    !character (len=14) :: cbedcond
-    !character (len=10), dimension(0:3) :: ctype
-    !character (len=15) :: nodestr
-    !!data
-    !data ctype(0) /'VERTICAL  '/
-    !data ctype(1) /'HORIZONTAL'/
-    !data ctype(2) /'EMBEDDEDH '/
-    !data ctype(3) /'EMBEDDEDV '/
-    ! -- format
-! ------------------------------------------------------------------------------
 
     !
-    ! -- initialize xnewpak and set lake concentration
+    ! -- initialize xnewpak and set feature concentration (or temperature)
     ! -- todo: this should be a time series?
     do n = 1, this%ncv
       this%xnewpak(n) = this%strt(n)
-      !write(text,'(g15.7)') this%strt(n)
-      !endtim = DZERO
-      !jj = 1    ! For STAGE
-      !call read_single_value_or_time_series(text, &
-      !                                      this%stage(n)%value, &
-      !                                      this%stage(n)%name, &
-      !                                      endtim, &
-      !                                      this%name, 'BND', this%TsManager, &
-      !                                      this%iprpak, n, jj, 'STAGE', &
-      !                                      this%featname(n), this%inunit)
-
+      !
       ! -- todo: read aux
-
+      !
       ! -- todo: read boundname
-
     end do
     !
     ! -- initialize status (iboundpak) of lakes to active
@@ -1818,21 +1721,20 @@ subroutine apt_read_initial_attr(this)
     ! -- copy boundname into boundname_cst
     call this%copy_boundname()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_read_initial_attr
 
+  !> @brief Add terms specific to advanced package transport to the explicit
+  !! solve
+  !!
+  !! Explicit solve for concentration (or temperature) in advaced package
+  !! features, which is an alternative to the iterative implicit solve.
+  !<
   subroutine apt_solve(this)
-! ******************************************************************************
-! apt_solve -- explicit solve for concentration in features, which is an
-!   alternative to the iterative implicit solve
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     use ConstantsModule, only: LINELENGTH
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     ! -- local
     integer(I4B) :: n, j, igwfnode
     integer(I4B) :: n1, n2
@@ -1840,10 +1742,8 @@ subroutine apt_solve(this)
     real(DP) :: ctmp
     real(DP) :: c1, qbnd
     real(DP) :: hcofval, rhsval
-! ------------------------------------------------------------------------------
-    !
     !
-    ! -- first initialize dbuff
+    ! -- initialize dbuff
     do n = 1, this%ncv
       this%dbuff(n) = DZERO
     end do
@@ -1863,13 +1763,13 @@ subroutine apt_solve(this)
     ! -- add from mover contribution
     if (this%idxbudfmvr /= 0) then
       do n1 = 1, size(this%qmfrommvr)
-        rrate = this%qmfrommvr(n1)
+        rrate = this%qmfrommvr(n1) ! Will be in terms of energy for heat transport
         this%dbuff(n1) = this%dbuff(n1) + rrate
       end do
     end if
     !
     ! -- go through each gwf connection and accumulate
-    !    total mass in dbuff mass
+    !    total mass (or energy) in dbuff mass
     do j = 1, this%flowbudptr%budterm(this%idxbudgwf)%nlist
       n = this%flowbudptr%budterm(this%idxbudgwf)%id1(j)
       this%hcof(j) = DZERO
@@ -1878,17 +1778,17 @@ subroutine apt_solve(this)
       qbnd = this%flowbudptr%budterm(this%idxbudgwf)%flow(j)
       if (qbnd <= DZERO) then
         ctmp = this%xnewpak(n)
-        this%rhs(j) = qbnd * ctmp
+        this%rhs(j) = qbnd * ctmp * this%eqnsclfac
       else
         ctmp = this%xnew(igwfnode)
-        this%hcof(j) = -qbnd
+        this%hcof(j) = -qbnd * this%eqnsclfac
       end if
-      c1 = qbnd * ctmp
+      c1 = qbnd * ctmp * this%eqnsclfac
       this%dbuff(n) = this%dbuff(n) + c1
     end do
     !
-    ! -- go through each lak-lak connection and accumulate
-    !    total mass in dbuff mass
+    ! -- go through each "within apt-apt" connection (e.g., lak-lak) and
+    !    accumulate total mass (or energy) in dbuff mass
     if (this%idxbudfjf /= 0) then
       do j = 1, this%flowbudptr%budterm(this%idxbudfjf)%nlist
         call this%apt_fjf_term(j, n1, n2, rrate)
@@ -1897,7 +1797,7 @@ subroutine apt_solve(this)
       end do
     end if
     !
-    ! -- calulate the feature concentration
+    ! -- calculate the feature concentration/temperature
     do n = 1, this%ncv
       call this%apt_stor_term(n, n1, n2, rrate, rhsval, hcofval)
       !
@@ -1916,17 +1816,15 @@ subroutine apt_solve(this)
     return
   end subroutine apt_solve
 
+  !> @brief Add terms specific to advanced package transport features to the
+  !! explicit solve routine
+  !!
+  !! This routine must be overridden by the specific apt package
+  !<
   subroutine pak_solve(this)
-! ******************************************************************************
-! pak_solve -- must be overridden
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- this routine should never be called
     call store_error('Program error: pak_solve not implemented.', &
@@ -1936,15 +1834,11 @@ subroutine pak_solve(this)
     return
   end subroutine pak_solve
 
+  !> @brief Accumulate constant concentration (or temperature) terms for budget
+  !<
   subroutine apt_accumulate_ccterm(this, ilak, rrate, ccratin, ccratout)
-! ******************************************************************************
-! apt_accumulate_ccterm -- Accumulate constant concentration terms for budget.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     integer(I4B), intent(in) :: ilak
     real(DP), intent(in) :: rrate
     real(DP), intent(inout) :: ccratin
@@ -1953,7 +1847,6 @@ subroutine apt_accumulate_ccterm(this, ilak, rrate, ccratin, ccratout)
     real(DP) :: q
     ! format
     ! code
-! ------------------------------------------------------------------------------
     !
     if (this%iboundpak(ilak) < 0) then
       q = -rrate
@@ -1970,20 +1863,16 @@ subroutine apt_accumulate_ccterm(this, ilak, rrate, ccratin, ccratout)
         ccratin = ccratin + q
       end if
     end if
-    ! -- return
+    !
+    ! -- Return
     return
   end subroutine apt_accumulate_ccterm
 
+  !> @brief Define the list heading that is written to iout when PRINT_INPUT
+  !! option is used.
+  !<
   subroutine define_listlabel(this)
-! ******************************************************************************
-! define_listlabel -- Define the list heading that is written to iout when
-!   PRINT_INPUT option is used.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    class(GwtAptType), intent(inout) :: this
-! ------------------------------------------------------------------------------
+    class(TspAptType), intent(inout) :: this
     !
     ! -- create the header list label
     this%listlabel = trim(this%filtyp)//' NO.'
@@ -2002,19 +1891,15 @@ subroutine define_listlabel(this)
       write (this%listlabel, '(a, a16)') trim(this%listlabel), 'BOUNDARY NAME'
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine define_listlabel
 
+  !> @brief Set pointers to model arrays and variables so that a package has
+  !! access to these items.
+  !<
   subroutine apt_set_pointers(this, neq, ibound, xnew, xold, flowja)
-! ******************************************************************************
-! set_pointers -- Set pointers to model arrays and variables so that a package
-!                 has access to these things.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     integer(I4B), pointer :: neq
     integer(I4B), dimension(:), pointer, contiguous :: ibound
     real(DP), dimension(:), pointer, contiguous :: xnew
@@ -2022,7 +1907,6 @@ subroutine apt_set_pointers(this, neq, ibound, xnew, xold, flowja)
     real(DP), dimension(:), pointer, contiguous :: flowja
     ! -- local
     integer(I4B) :: istart, iend
-! ------------------------------------------------------------------------------
     !
     ! -- call base BndType set_pointers
     call this%BndType%set_pointers(neq, ibound, xnew, xold, flowja)
@@ -2037,25 +1921,21 @@ subroutine apt_set_pointers(this, neq, ibound, xnew, xold, flowja)
       this%xnewpak => this%xnew(istart:iend)
     end if
     !
-    ! -- return
+    ! -- Return
+    return
   end subroutine apt_set_pointers
 
+  !> @brief Return the feature new volume and old volume
+  !<
   subroutine get_volumes(this, icv, vnew, vold, delt)
-! ******************************************************************************
-! get_volumes -- return the feature new volume and old volume
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     integer(I4B), intent(in) :: icv
     real(DP), intent(inout) :: vnew, vold
     real(DP), intent(in) :: delt
     ! -- local
     real(DP) :: qss
-! ------------------------------------------------------------------------------
     !
     ! -- get volumes
     vold = DZERO
@@ -2070,39 +1950,34 @@ subroutine get_volumes(this, icv, vnew, vold, delt)
     return
   end subroutine get_volumes
 
+  !> @brief Function to return the number of budget terms just for this package
+  !!
+  !! This function must be overridden.
+  !<
   function pak_get_nbudterms(this) result(nbudterms)
-! ******************************************************************************
-! pak_get_nbudterms -- function to return the number of budget terms just for
-!   this package.  Must be overridden.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     ! -- return
     integer(I4B) :: nbudterms
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- this routine should never be called
     call store_error('Program error: pak_get_nbudterms not implemented.', &
                      terminate=.TRUE.)
     nbudterms = 0
+    !
+    ! -- Return
+    return
   end function pak_get_nbudterms
 
+  !> @brief Set up the budget object that stores advanced package flow terms
+  !<
   subroutine apt_setup_budobj(this)
-! ******************************************************************************
-! apt_setup_budobj -- Set up the budget object that stores all the lake flows
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LENBUDTXT
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     ! -- local
     integer(I4B) :: nbudterm
     integer(I4B) :: nlen
@@ -2111,9 +1986,12 @@ subroutine apt_setup_budobj(this)
     integer(I4B) :: idx
     logical :: ordered_id1
     real(DP) :: q
-    character(len=LENBUDTXT) :: text
+    character(len=LENBUDTXT) :: bddim_opt
+    character(len=LENBUDTXT) :: text, textt
     character(len=LENBUDTXT), dimension(1) :: auxtxt
-! ------------------------------------------------------------------------------
+    !
+    ! -- initialize nbudterm
+    nbudterm = 0
     !
     ! -- Determine if there are flow-ja-face terms
     nlen = 0
@@ -2121,17 +1999,18 @@ subroutine apt_setup_budobj(this)
       nlen = this%flowbudptr%budterm(this%idxbudfjf)%maxlist
     end if
     !
-    ! -- Determine the number of lake budget terms. These are fixed for
-    !    the simulation and cannot change
-    ! -- the first 3 is for GWF, STORAGE, and CONSTANT
-    nbudterm = 3
+    ! -- Determine the number of budget terms associated with apt.
+    !    These are fixed for the simulation and cannot change
+    !
+    ! -- add one if flow-ja-face present
+    if (this%idxbudfjf /= 0) nbudterm = nbudterm + 1
+    !
+    ! -- All the APT packages have GWF, STORAGE, and CONSTANT
+    nbudterm = nbudterm + 3
     !
     ! -- add terms for the specific package
     nbudterm = nbudterm + this%pak_get_nbudterms()
     !
-    ! -- add one for flow-ja-face
-    if (nlen > 0) nbudterm = nbudterm + 1
-    !
     ! -- add for mover terms and auxiliary
     if (this%idxbudtmvr /= 0) nbudterm = nbudterm + 1
     if (this%idxbudfmvr /= 0) nbudterm = nbudterm + 1
@@ -2139,8 +2018,10 @@ subroutine apt_setup_budobj(this)
     !
     ! -- set up budobj
     call budgetobject_cr(this%budobj, this%packName)
+    !
+    bddim_opt = this%depvarunitabbrev
     call this%budobj%budgetobject_df(this%ncv, nbudterm, 0, 0, &
-                                     bddim_opt='M', ibudcsv=this%ibudcsv)
+                                     bddim_opt=bddim_opt, ibudcsv=this%ibudcsv)
     idx = 0
     !
     ! -- Go through and set up each budget term
@@ -2189,14 +2070,17 @@ subroutine apt_setup_budobj(this)
     end do
     !
     ! -- Reserve space for the package specific terms
+    this%idxprepak = idx
     call this%pak_setup_budobj(idx)
+    this%idxlastpak = idx
     !
     ! --
     text = '         STORAGE'
     idx = idx + 1
     maxlist = this%flowbudptr%budterm(this%idxbudsto)%maxlist
     naux = 1
-    auxtxt(1) = '            MASS'
+    write (textt, '(a)') str_pad_left(this%depvarunit, 16)
+    auxtxt(1) = textt ! '            MASS' or '          ENERGY'
     call this%budobj%budterm(idx)%initialize(text, &
                                              this%name_model, &
                                              this%packName, &
@@ -2272,45 +2156,38 @@ subroutine apt_setup_budobj(this)
       call this%budobj%flowtable_df(this%iout)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_setup_budobj
 
+  !> @brief Set up a budget object that stores an advanced package flows
+  !!
+  !! Individual packages set up their budget terms.  Must be overridden.
+  !<
   subroutine pak_setup_budobj(this, idx)
-! ******************************************************************************
-! pak_setup_budobj -- Individual packages set up their budget terms.  Must
-!   be overridden
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     integer(I4B), intent(inout) :: idx
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- this routine should never be called
     call store_error('Program error: pak_setup_budobj not implemented.', &
                      terminate=.TRUE.)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine pak_setup_budobj
 
-  subroutine apt_fill_budobj(this, x)
-! ******************************************************************************
-! apt_fill_budobj -- copy flow terms into this%budobj
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Copy flow terms into this%budobj
+  !<
+  subroutine apt_fill_budobj(this, x, flowja)
     ! -- modules
     use TdisModule, only: delt
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     real(DP), dimension(:), intent(in) :: x
+    real(DP), dimension(:), contiguous, intent(inout) :: flowja
     ! -- local
     integer(I4B) :: naux
     real(DP), dimension(:), allocatable :: auxvartmp
@@ -2323,19 +2200,18 @@ subroutine apt_fill_budobj(this, x)
     real(DP) :: v0, v1
     real(DP) :: ccratin, ccratout
     ! -- formats
-! -----------------------------------------------------------------------------
     !
     ! -- initialize counter
     idx = 0
     !
-    ! -- initialize ccterm, which is used to sum up all mass flows
-    !    into a constant concentration cell
+    ! -- initialize ccterm, which is used to sum up all mass (or energy) flows
+    !    into a constant concentration (or temperature) cell
     ccratin = DZERO
     ccratout = DZERO
     do n1 = 1, this%ncv
       this%ccterm(n1) = DZERO
     end do
-
+    !
     ! -- FLOW JA FACE
     nlen = 0
     if (this%idxbudfjf /= 0) then
@@ -2352,7 +2228,7 @@ subroutine apt_fill_budobj(this, x)
         call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
       end do
     end if
-
+    !
     ! -- GWF (LEAKAGE)
     idx = idx + 1
     call this%budobj%budterm(idx)%reset(this%maxbound)
@@ -2367,23 +2243,24 @@ subroutine apt_fill_budobj(this, x)
       call this%budobj%budterm(idx)%update_term(n1, igwfnode, q)
       call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
     end do
-
-    ! -- individual package terms
-    call this%pak_fill_budobj(idx, x, ccratin, ccratout)
-
+    !
+    ! -- skip individual package terms for now and process them last
+    ! -- in case they depend on the other terms (as for uze)
+    idx = this%idxlastpak
+    !
     ! -- STORAGE
     idx = idx + 1
     call this%budobj%budterm(idx)%reset(this%ncv)
     allocate (auxvartmp(1))
     do n1 = 1, this%ncv
       call this%get_volumes(n1, v1, v0, delt)
-      auxvartmp(1) = v1 * this%xnewpak(n1)
+      auxvartmp(1) = v1 * this%xnewpak(n1) ! Note: When GWE is added, check if this needs a factor of eqnsclfac
       q = this%qsto(n1)
       call this%budobj%budterm(idx)%update_term(n1, n1, q, auxvartmp)
       call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
     end do
     deallocate (auxvartmp)
-
+    !
     ! -- TO MOVER
     if (this%idxbudtmvr /= 0) then
       idx = idx + 1
@@ -2395,19 +2272,19 @@ subroutine apt_fill_budobj(this, x)
         call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
       end do
     end if
-
+    !
     ! -- FROM MOVER
     if (this%idxbudfmvr /= 0) then
       idx = idx + 1
       nlist = this%ncv
       call this%budobj%budterm(idx)%reset(nlist)
-      do n1 = 1, nlist
-        q = this%qmfrommvr(n1)
+      do j = 1, nlist
+        call this%apt_fmvr_term(j, n1, n2, q)
         call this%budobj%budterm(idx)%update_term(n1, n1, q)
         call this%apt_accumulate_ccterm(n1, q, ccratin, ccratout)
       end do
     end if
-
+    !
     ! -- CONSTANT FLOW
     idx = idx + 1
     call this%budobj%budterm(idx)%reset(this%ncv)
@@ -2415,7 +2292,7 @@ subroutine apt_fill_budobj(this, x)
       q = this%ccterm(n1)
       call this%budobj%budterm(idx)%update_term(n1, n1, q)
     end do
-
+    !
     ! -- AUXILIARY VARIABLES
     naux = this%naux
     if (naux > 0) then
@@ -2432,43 +2309,44 @@ subroutine apt_fill_budobj(this, x)
       deallocate (auxvartmp)
     end if
     !
+    ! -- individual package terms processed last
+    idx = this%idxprepak
+    call this%pak_fill_budobj(idx, x, ccratin, ccratout)
+    !
     ! --Terms are filled, now accumulate them for this time step
     call this%budobj%accumulate_terms()
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_fill_budobj
 
+  !> @brief Copy flow terms into this%budobj, must be overridden
+  !<
   subroutine pak_fill_budobj(this, idx, x, ccratin, ccratout)
-! ******************************************************************************
-! pak_fill_budobj -- copy flow terms into this%budobj, must be overridden
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     integer(I4B), intent(inout) :: idx
     real(DP), dimension(:), intent(in) :: x
     real(DP), intent(inout) :: ccratin
     real(DP), intent(inout) :: ccratout
     ! -- local
     ! -- formats
-! -----------------------------------------------------------------------------
     !
     ! -- this routine should never be called
     call store_error('Program error: pak_fill_budobj not implemented.', &
                      terminate=.TRUE.)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine pak_fill_budobj
 
+  !> @brief Account for mass or energy storage in advanced package features
+  !<
   subroutine apt_stor_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
     use TdisModule, only: delt
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     integer(I4B), intent(in) :: ientry
     integer(I4B), intent(inout) :: n1
     integer(I4B), intent(inout) :: n2
@@ -2477,53 +2355,96 @@ subroutine apt_stor_term(this, ientry, n1, n2, rrate, &
     real(DP), intent(inout), optional :: hcofval
     real(DP) :: v0, v1
     real(DP) :: c0, c1
+    !
     n1 = ientry
     n2 = ientry
     call this%get_volumes(n1, v1, v0, delt)
     c0 = this%xoldpak(n1)
     c1 = this%xnewpak(n1)
-    if (present(rrate)) rrate = -c1 * v1 / delt + c0 * v0 / delt
-    if (present(rhsval)) rhsval = -c0 * v0 / delt
-    if (present(hcofval)) hcofval = -v1 / delt
+    if (present(rrate)) then
+      rrate = (-c1 * v1 / delt + c0 * v0 / delt) * this%eqnsclfac
+    end if
+    if (present(rhsval)) rhsval = -c0 * v0 * this%eqnsclfac / delt
+    if (present(hcofval)) hcofval = -v1 * this%eqnsclfac / delt
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_stor_term
 
+  !> @brief Account for mass or energy transferred to the MVR package
+  !<
   subroutine apt_tmvr_term(this, ientry, n1, n2, rrate, &
                            rhsval, hcofval)
-    class(GwtAptType) :: this
+    ! -- modules
+    ! -- dummy
+    class(TspAptType) :: this
     integer(I4B), intent(in) :: ientry
     integer(I4B), intent(inout) :: n1
     integer(I4B), intent(inout) :: n2
     real(DP), intent(inout), optional :: rrate
     real(DP), intent(inout), optional :: rhsval
     real(DP), intent(inout), optional :: hcofval
+    ! -- local
     real(DP) :: qbnd
     real(DP) :: ctmp
+    !
+    ! -- Calculate MVR-related terms
     n1 = this%flowbudptr%budterm(this%idxbudtmvr)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudtmvr)%id2(ientry)
     qbnd = this%flowbudptr%budterm(this%idxbudtmvr)%flow(ientry)
     ctmp = this%xnewpak(n1)
-    if (present(rrate)) rrate = ctmp * qbnd
+    if (present(rrate)) rrate = ctmp * qbnd * this%eqnsclfac
     if (present(rhsval)) rhsval = DZERO
-    if (present(hcofval)) hcofval = qbnd
+    if (present(hcofval)) hcofval = qbnd * this%eqnsclfac
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_tmvr_term
 
+  !> @brief Account for mass or energy transferred to this package from the
+  !! MVR package
+  !<
+  subroutine apt_fmvr_term(this, ientry, n1, n2, rrate, &
+                           rhsval, hcofval)
+    ! -- modules
+    ! -- dummy
+    class(TspAptType) :: this
+    integer(I4B), intent(in) :: ientry
+    integer(I4B), intent(inout) :: n1
+    integer(I4B), intent(inout) :: n2
+    real(DP), intent(inout), optional :: rrate
+    real(DP), intent(inout), optional :: rhsval
+    real(DP), intent(inout), optional :: hcofval
+    !
+    ! -- Calculate MVR-related terms
+    n1 = ientry
+    n2 = n1
+    if (present(rrate)) rrate = this%qmfrommvr(n1) ! NOTE: When bringing in GWE, ensure this is in terms of energy. Might need to apply eqnsclfac here.
+    if (present(rhsval)) rhsval = this%qmfrommvr(n1)
+    if (present(hcofval)) hcofval = DZERO
+    !
+    ! -- Return
+    return
+  end subroutine apt_fmvr_term
+
+  !> @brief Go through each "within apt-apt" connection (e.g., lkt-lkt, or
+  !! sft-sft) and accumulate total mass (or energy) in dbuff mass
+  !<
   subroutine apt_fjf_term(this, ientry, n1, n2, rrate, &
                           rhsval, hcofval)
-    class(GwtAptType) :: this
+    ! -- modules
+    ! -- dummy
+    class(TspAptType) :: this
     integer(I4B), intent(in) :: ientry
     integer(I4B), intent(inout) :: n1
     integer(I4B), intent(inout) :: n2
     real(DP), intent(inout), optional :: rrate
     real(DP), intent(inout), optional :: rhsval
     real(DP), intent(inout), optional :: hcofval
+    ! -- local
     real(DP) :: qbnd
     real(DP) :: ctmp
+    !
     n1 = this%flowbudptr%budterm(this%idxbudfjf)%id1(ientry)
     n2 = this%flowbudptr%budterm(this%idxbudfjf)%id2(ientry)
     qbnd = this%flowbudptr%budterm(this%idxbudfjf)%flow(ientry)
@@ -2532,27 +2453,23 @@ subroutine apt_fjf_term(this, ientry, n1, n2, rrate, &
     else
       ctmp = this%xnewpak(n2)
     end if
-    if (present(rrate)) rrate = ctmp * qbnd
-    if (present(rhsval)) rhsval = -rrate
+    if (present(rrate)) rrate = ctmp * qbnd * this%eqnsclfac
+    if (present(rhsval)) rhsval = -rrate * this%eqnsclfac
     if (present(hcofval)) hcofval = DZERO
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_fjf_term
 
+  !> @brief Copy concentrations (or temperatures) into flow package aux
+  !! variable
+  !<
   subroutine apt_copy2flowp(this)
-! ******************************************************************************
-! apt_copy2flowp -- copy concentrations into flow package aux variable
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     ! -- local
     integer(I4B) :: n, j
-! ------------------------------------------------------------------------------
     !
     ! -- copy
     if (this%iauxfpconc /= 0) then
@@ -2566,82 +2483,73 @@ subroutine apt_copy2flowp(this)
       end do
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_copy2flowp
 
+  !> @brief Determine whether an obs type is supported
+  !!
+  !! This function:
+  !!   - returns true if APT package supports named observation.
+  !!   - overrides BndType%bnd_obs_supported()
+  !<
   logical function apt_obs_supported(this)
-! ******************************************************************************
-! apt_obs_supported -- obs are supported?
-!   -- Return true because APT package supports observations.
-!   -- Overrides BndType%bnd_obs_supported()
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAptType) :: this
-! ------------------------------------------------------------------------------
+    class(TspAptType) :: this
     !
     ! -- Set to true
     apt_obs_supported = .true.
     !
-    ! -- return
+    ! -- Return
     return
   end function apt_obs_supported
 
+  !> @brief Define observation type
+  !!
+  !! This routine:
+  !!   - stores observation types supported by APT package.
+  !!   - overrides BndType%bnd_df_obs
+  !<
   subroutine apt_df_obs(this)
-! ******************************************************************************
-! apt_df_obs -- obs are supported?
-!   -- Store observation type supported by APT package.
-!   -- Overrides BndType%bnd_df_obs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- call additional specific observations for lkt, sft, mwt, and uzt
     call this%pak_df_obs()
     !
+    ! -- Return
     return
   end subroutine apt_df_obs
 
+  !> @brief Define apt observation type
+  !!
+  !! This routine:
+  !!   - stores observations supported by the APT package
+  !!   - must be overridden by child class
   subroutine pak_df_obs(this)
-! ******************************************************************************
-! pak_df_obs -- obs are supported?
-!   -- Store observation type supported by APT package.
-!   -- must be overridden by child class
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- this routine should never be called
     call store_error('Program error: pak_df_obs not implemented.', &
                      terminate=.TRUE.)
     !
+    ! -- Return
     return
   end subroutine pak_df_obs
 
   !> @brief Process package specific obs
-    !!
-    !! Method to process specific observations for this package.
-    !!
+  !!
+  !! Method to process specific observations for this package.
   !<
   subroutine pak_rp_obs(this, obsrv, found)
     ! -- dummy
-    class(GwtAptType), intent(inout) :: this !< package class
+    class(TspAptType), intent(inout) :: this !< package class
     type(ObserveType), intent(inout) :: obsrv !< observation object
     logical, intent(inout) :: found !< indicate whether observation was found
     ! -- local
@@ -2650,17 +2558,17 @@ subroutine pak_rp_obs(this, obsrv, found)
     call store_error('Program error: pak_rp_obs not implemented.', &
                      terminate=.TRUE.)
     !
+    ! -- Return
     return
   end subroutine pak_rp_obs
 
   !> @brief Prepare observation
-    !!
-    !! Find the indices for this observation assuming
-    !! they are indexed by feature number
-    !!
+  !!
+  !! Find the indices for this observation assuming they are indexed by
+  !! feature number
   !<
   subroutine rp_obs_byfeature(this, obsrv)
-    class(GwtAptType), intent(inout) :: this !< object
+    class(TspAptType), intent(inout) :: this !< object
     type(ObserveType), intent(inout) :: obsrv !< observation
     integer(I4B) :: nn1
     integer(I4B) :: j
@@ -2695,18 +2603,18 @@ subroutine rp_obs_byfeature(this, obsrv)
       end if
       call obsrv%AddObsIndex(nn1)
     end if
+    !
+    ! -- Return
     return
   end subroutine rp_obs_byfeature
 
   !> @brief Prepare observation
-    !!
-    !! Find the indices for this observation assuming
-    !! they are first indexed by feature number and
-    !! secondly by a connection number
-    !!
+  !!
+  !! Find the indices for this observation assuming they are first indexed
+  !! by feature number and secondly by a connection number
   !<
   subroutine rp_obs_budterm(this, obsrv, budterm)
-    class(GwtAptType), intent(inout) :: this !< object
+    class(TspAptType), intent(inout) :: this !< object
     type(ObserveType), intent(inout) :: obsrv !< observation
     type(BudgetTermType), intent(in) :: budterm !< budget term
     integer(I4B) :: nn1
@@ -2770,18 +2678,18 @@ subroutine rp_obs_budterm(this, obsrv, budterm)
         call store_error(errmsg)
       end if
     end if
+    !
+    ! -- Return
     return
   end subroutine rp_obs_budterm
 
   !> @brief Prepare observation
-    !!
-    !! Find the indices for this observation assuming
-    !! they are first indexed by a feature number and
-    !! secondly by a second feature number
-    !!
+  !!
+  !! Find the indices for this observation assuming they are first indexed
+  !! by a feature number and secondly by a second feature number
   !<
   subroutine rp_obs_flowjaface(this, obsrv, budterm)
-    class(GwtAptType), intent(inout) :: this !< object
+    class(TspAptType), intent(inout) :: this !< object
     type(ObserveType), intent(inout) :: obsrv !< observation
     type(BudgetTermType), intent(in) :: budterm !< budget term
     integer(I4B) :: nn1
@@ -2847,38 +2755,38 @@ subroutine rp_obs_flowjaface(this, obsrv, budterm)
         call store_error(errmsg)
       end if
     end if
+    !
+    ! -- Return
     return
   end subroutine rp_obs_flowjaface
 
+  !> @brief Read and prepare apt-related observations
+  !!
+  !! Method to process specific observations for an apt package
+  !<
   subroutine apt_rp_obs(this)
-! ******************************************************************************
-! apt_rp_obs --
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: kper
     ! -- dummy
-    class(GwtAptType), intent(inout) :: this
+    class(TspAptType), intent(inout) :: this
     ! -- local
     integer(I4B) :: i
     logical :: found
     class(ObserveType), pointer :: obsrv => null()
-! ------------------------------------------------------------------------------
     !
     if (kper == 1) then
       do i = 1, this%obs%npakobs
         obsrv => this%obs%pakobs(i)%obsrv
         select case (obsrv%ObsTypeId)
-        case ('CONCENTRATION')
+        case ('CONCENTRATION', 'TEMPERATURE')
           call this%rp_obs_byfeature(obsrv)
           !
           ! -- catch non-cumulative observation assigned to observation defined
           !    by a boundname that is assigned to more than one element
           if (obsrv%indxbnds_count > 1) then
-            write (errmsg, '(a, a, a)') &
-              'CONCENTRATION for observation', trim(adjustl(obsrv%Name)), &
+            write (errmsg, '(a, a, a, a)') &
+              trim(adjustl(this%depvartype))// &
+              ' for observation', trim(adjustl(obsrv%Name)), &
               ' must be assigned to a feature with a unique boundname.'
             call store_error(errmsg)
           end if
@@ -2927,20 +2835,20 @@ subroutine apt_rp_obs(this)
       end if
     end if
     !
+    ! -- Return
     return
   end subroutine apt_rp_obs
 
+  !> @brief Calculate observation values
+  !!
+  !! Routine calculates observations common to SFT/LKT/MWT/UZT
+  !! (or SFE/LKE/MWE/UZE) for as many TspAptType observations that are common
+  !! among the advanced transport packages
+  !<
   subroutine apt_bd_obs(this)
-! ******************************************************************************
-! apt_bd_obs -- Calculate observations common to SFT/LKT/MWT/UZT
-!      ObsType%SaveOneSimval for each GwtAptType observation.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     ! -- local
     integer(I4B) :: i
     integer(I4B) :: igwfnode
@@ -2954,7 +2862,7 @@ subroutine apt_bd_obs(this)
     logical :: found
 ! ------------------------------------------------------------------------------
     !
-    ! -- Write simulated values for all LAK observations
+    ! -- Write simulated values for all Advanced Package observations
     if (this%obs%npakobs > 0) then
       call this%obs%obs_bd_clear()
       do i = 1, this%obs%npakobs
@@ -2963,7 +2871,7 @@ subroutine apt_bd_obs(this)
           v = DNODATA
           jj = obsrv%indxbnds(j)
           select case (obsrv%ObsTypeId)
-          case ('CONCENTRATION')
+          case ('CONCENTRATION', 'TEMPERATURE')
             if (this%iboundpak(jj) /= 0) then
               v = this%xnewpak(jj)
             end if
@@ -2989,7 +2897,7 @@ subroutine apt_bd_obs(this)
             end if
           case ('FROM-MVR')
             if (this%iboundpak(jj) /= 0 .and. this%idxbudfmvr > 0) then
-              v = this%qmfrommvr(jj)
+              call this%apt_fmvr_term(jj, n1, n2, v)
             end if
           case ('TO-MVR')
             if (this%idxbudtmvr > 0) then
@@ -3023,38 +2931,33 @@ subroutine apt_bd_obs(this)
       end if
     end if
     !
+    ! -- Return
     return
   end subroutine apt_bd_obs
 
+  !> @brief Check if observation exists in an advanced package
+  !<
   subroutine pak_bd_obs(this, obstypeid, jj, v, found)
-! ******************************************************************************
-! pak_bd_obs --
-!   -- check for observations in concrete packages.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
-    class(GwtAptType), intent(inout) :: this
+    class(TspAptType), intent(inout) :: this
     character(len=*), intent(in) :: obstypeid
     integer(I4B), intent(in) :: jj
     real(DP), intent(inout) :: v
     logical, intent(inout) :: found
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- set found = .false. because obstypeid is not known
     found = .false.
     !
+    ! -- Return
     return
   end subroutine pak_bd_obs
 
-  !> @brief Process observation IDs for a package
-    !!
-    !! Method to process observation ID strings for an APT package.
-    !! This processor is only for observation types that support ID1
-    !! and not ID2.
-    !!
+  !> @brief Process observation IDs for an advanced package
+  !!
+  !! Method to process observation ID strings for an APT package.
+  !! This processor is only for observation types that support ID1
+  !! and not ID2.
   !<
   subroutine apt_process_obsID(obsrv, dis, inunitobs, iout)
     ! -- dummy variables
@@ -3097,11 +3000,10 @@ subroutine apt_process_obsID(obsrv, dis, inunitobs, iout)
   end subroutine apt_process_obsID
 
   !> @brief Process observation IDs for a package
-    !!
-    !! Method to process observation ID strings for an APT package.
-    !! This processor is for the case where if ID1 is an integer
-    !! then ID2 must be provided.
-    !!
+  !!
+  !! Method to process observation ID strings for an APT package. This
+  !! processor is for the case where if ID1 is an integer then ID2 must be
+  !! provided.
   !<
   subroutine apt_process_obsID12(obsrv, dis, inunitobs, iout)
     ! -- dummy variables
@@ -3146,28 +3048,25 @@ subroutine apt_process_obsID12(obsrv, dis, inunitobs, iout)
     ! -- store reach number (NodeNumber)
     obsrv%NodeNumber = nn1
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine apt_process_obsID12
 
+  !> @brief Setup a table object an advanced package
+  !!
+  !! Set up the table object that is used to write the apt concentration
+  !! (or temperature) data. The terms listed here must correspond in the
+  !! apt_ot method.
+  !<
   subroutine apt_setup_tableobj(this)
-! ******************************************************************************
-! apt_setup_tableobj -- Set up the table object that is used to write the apt
-!                       conc data. The terms listed here must correspond in
-!                       in the apt_ot method.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH, LENBUDTXT
     ! -- dummy
-    class(GwtAptType) :: this
+    class(TspAptType) :: this
     ! -- local
     integer(I4B) :: nterms
     character(len=LINELENGTH) :: title
     character(len=LINELENGTH) :: text_temp
-! ------------------------------------------------------------------------------
     !
     ! -- setup well head table
     if (this%iprconc > 0) then
@@ -3179,7 +3078,8 @@ subroutine apt_setup_tableobj(this)
       ! -- set up table title
       title = trim(adjustl(this%text))//' PACKAGE ('// &
               trim(adjustl(this%packName))// &
-              ') CONCENTRATION FOR EACH CONTROL VOLUME'
+              ') '//trim(adjustl(this%depvartype))// &
+              &' FOR EACH CONTROL VOLUME'
       !
       ! -- set up dv tableobj
       call table_cr(this%dvtab, this%packName, title)
@@ -3197,7 +3097,7 @@ subroutine apt_setup_tableobj(this)
       call this%dvtab%initialize_column(text_temp, 10, alignment=TABCENTER)
       !
       ! -- feature conc
-      text_temp = 'CONC'
+      text_temp = this%depvartype(1:4)
       call this%dvtab%initialize_column(text_temp, 12, alignment=TABCENTER)
     end if
     !
@@ -3205,4 +3105,4 @@ subroutine apt_setup_tableobj(this)
     return
   end subroutine apt_setup_tableobj
 
-end module GwtAptModule
+end module TspAptModule
diff --git a/src/Model/TransportModel/tsp1fmi1.f90 b/src/Model/TransportModel/tsp1fmi1.f90
new file mode 100644
index 00000000000..fe92e15fdcf
--- /dev/null
+++ b/src/Model/TransportModel/tsp1fmi1.f90
@@ -0,0 +1,973 @@
+module TspFmiModule
+
+  use KindModule, only: DP, I4B
+  use ConstantsModule, only: DONE, DZERO, DHALF, LINELENGTH, LENBUDTXT, &
+                             LENPACKAGENAME, LENVARNAME
+  use SimModule, only: store_error, store_error_unit
+  use SimVariablesModule, only: errmsg
+  use FlowModelInterfaceModule, only: FlowModelInterfaceType
+  use BaseDisModule, only: DisBaseType
+  use ListModule, only: ListType
+  use BudgetFileReaderModule, only: BudgetFileReaderType
+  use HeadFileReaderModule, only: HeadFileReaderType
+  use PackageBudgetModule, only: PackageBudgetType
+  use BudgetObjectModule, only: BudgetObjectType, budgetobject_cr_bfr
+  use MatrixBaseModule
+
+  implicit none
+  private
+  public :: TspFmiType
+  public :: fmi_cr
+
+  character(len=LENPACKAGENAME) :: text = '    GWTFMI'
+
+  integer(I4B), parameter :: NBDITEMS = 2
+  character(len=LENBUDTXT), dimension(NBDITEMS) :: budtxt
+  data budtxt/'      FLOW-ERROR', ' FLOW-CORRECTION'/
+
+  type :: DataAdvancedPackageType
+    real(DP), dimension(:), contiguous, pointer :: concpack => null()
+    real(DP), dimension(:), contiguous, pointer :: qmfrommvr => null()
+  end type
+
+  type :: BudObjPtrArray
+    type(BudgetObjectType), pointer :: ptr
+  end type BudObjPtrArray
+
+  type, extends(FlowModelInterfaceType) :: TspFmiType
+
+    integer(I4B), dimension(:), pointer, contiguous :: iatp => null() !< advanced transport package applied to gwfpackages
+    integer(I4B), pointer :: iflowerr => null() !< add the flow error correction
+    real(DP), dimension(:), pointer, contiguous :: flowcorrect => null() !< mass flow correction
+    real(DP), pointer :: eqnsclfac => null() !< governing equation scale factor; =1. for solute; =rhow*cpw for energy
+    type(DataAdvancedPackageType), &
+      dimension(:), pointer, contiguous :: datp => null()
+    type(BudObjPtrArray), dimension(:), allocatable :: aptbudobj !< flow budget objects for the advanced packages
+
+  contains
+
+    procedure :: allocate_arrays => gwtfmi_allocate_arrays
+    procedure :: allocate_gwfpackages => gwtfmi_allocate_gwfpackages
+    procedure :: allocate_scalars => gwtfmi_allocate_scalars
+    procedure :: deallocate_gwfpackages => gwtfmi_deallocate_gwfpackages
+    procedure :: fmi_rp
+    procedure :: fmi_ad
+    procedure :: fmi_fc
+    procedure :: fmi_cq
+    procedure :: fmi_bd
+    procedure :: fmi_ot_flow
+    procedure :: fmi_da => gwtfmi_da
+    procedure :: gwfsatold
+    procedure :: initialize_gwfterms_from_bfr
+    procedure :: initialize_gwfterms_from_gwfbndlist
+    procedure :: read_options => gwtfmi_read_options
+    procedure :: set_aptbudobj_pointer
+    procedure :: read_packagedata => gwtfmi_read_packagedata
+
+  end type TspFmiType
+
+contains
+
+  !> @breif Create a new FMI object
+  !<
+  subroutine fmi_cr(fmiobj, name_model, inunit, iout, eqnsclfac, depvartype)
+    ! -- dummy
+    type(TspFmiType), pointer :: fmiobj
+    character(len=*), intent(in) :: name_model
+    integer(I4B), intent(in) :: inunit
+    integer(I4B), intent(in) :: iout
+    real(DP), intent(in), pointer :: eqnsclfac !< governing equation scale factor
+    character(len=LENVARNAME), intent(in) :: depvartype
+    !
+    ! -- Create the object
+    allocate (fmiobj)
+    !
+    ! -- create name and memory path
+    call fmiobj%set_names(1, name_model, 'FMI', 'FMI')
+    fmiobj%text = text
+    !
+    ! -- Allocate scalars
+    call fmiobj%allocate_scalars()
+    !
+    ! -- Set variables
+    fmiobj%inunit = inunit
+    fmiobj%iout = iout
+    !
+    ! -- Initialize block parser
+    call fmiobj%parser%Initialize(fmiobj%inunit, fmiobj%iout)
+    !
+    ! -- Assign label based on dependent variable
+    fmiobj%depvartype = depvartype
+    !
+    ! -- Store pointer to governing equation scale factor
+    fmiobj%eqnsclfac => eqnsclfac
+    !
+    ! -- Return
+    return
+  end subroutine fmi_cr
+
+  !> @brief Read and prepare
+  !<
+  subroutine fmi_rp(this, inmvr)
+    ! -- modules
+    use TdisModule, only: kper, kstp
+    ! -- dummy
+    class(TspFmiType) :: this
+    integer(I4B), intent(in) :: inmvr
+    ! -- local
+    ! -- formats
+    !
+    ! --Check to make sure MVT Package is active if mvr flows are available.
+    !   This cannot be checked until RP because exchange doesn't set a pointer
+    !   to mvrbudobj until exg_ar().
+    if (kper * kstp == 1) then
+      if (associated(this%mvrbudobj) .and. inmvr == 0) then
+        write (errmsg, '(a)') 'GWF water mover is active but the GWT MVT &
+          &package has not been specified.  activate GWT MVT package.'
+        call store_error(errmsg, terminate=.TRUE.)
+      end if
+      if (.not. associated(this%mvrbudobj) .and. inmvr > 0) then
+        write (errmsg, '(a)') 'GWF water mover terms are not available &
+          &but the GWT MVT package has been activated.  Activate GWF-GWT &
+          &exchange or specify GWFMOVER in FMI PACKAGEDATA.'
+        call store_error(errmsg, terminate=.TRUE.)
+      end if
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine fmi_rp
+
+  !> @brief Advance routine for FMI object
+  !<
+  subroutine fmi_ad(this, cnew)
+    ! -- modules
+    use ConstantsModule, only: DHDRY
+    ! -- dummy
+    class(TspFmiType) :: this
+    real(DP), intent(inout), dimension(:) :: cnew
+    ! -- local
+    integer(I4B) :: n
+    integer(I4B) :: m
+    integer(I4B) :: ipos
+    real(DP) :: crewet, tflow, flownm
+    character(len=15) :: nodestr
+    character(len=*), parameter :: fmtdry = &
+     &"(/1X,'WARNING: DRY CELL ENCOUNTERED AT ',a,';  RESET AS INACTIVE &
+     &WITH DRY CONCENTRATION = ', G13.5)"
+    character(len=*), parameter :: fmtrewet = &
+     &"(/1X,'DRY CELL REACTIVATED AT ', a,&
+     &' WITH STARTING CONCENTRATION =',G13.5)"
+    !
+    ! -- Set flag to indicated that flows are being updated.  For the case where
+    !    flows may be reused (only when flows are read from a file) then set
+    !    the flag to zero to indicated that flows were not updated
+    this%iflowsupdated = 1
+    !
+    ! -- If reading flows from a budget file, read the next set of records
+    if (this%iubud /= 0) then
+      call this%advance_bfr()
+    end if
+    !
+    ! -- If reading heads from a head file, read the next set of records
+    if (this%iuhds /= 0) then
+      call this%advance_hfr()
+    end if
+    !
+    ! -- If mover flows are being read from file, read the next set of records
+    if (this%iumvr /= 0) then
+      call this%mvrbudobj%bfr_advance(this%dis, this%iout)
+    end if
+    !
+    ! -- If advanced package flows are being read from file, read the next set of records
+    if (this%flows_from_file .and. this%inunit /= 0) then
+      do n = 1, size(this%aptbudobj)
+        call this%aptbudobj(n)%ptr%bfr_advance(this%dis, this%iout)
+      end do
+    end if
+    !
+    ! -- if flow cell is dry, then set gwt%ibound = 0 and conc to dry
+    do n = 1, this%dis%nodes
+      !
+      ! -- Calculate the ibound-like array that has 0 if saturation
+      !    is zero and 1 otherwise
+      if (this%gwfsat(n) > DZERO) then
+        this%ibdgwfsat0(n) = 1
+      else
+        this%ibdgwfsat0(n) = 0
+      end if
+      !
+      ! -- Check if active transport cell is inactive for flow
+      if (this%ibound(n) > 0) then
+        if (this%gwfhead(n) == DHDRY) then
+          ! -- transport cell should be made inactive
+          this%ibound(n) = 0
+          cnew(n) = DHDRY
+          call this%dis%noder_to_string(n, nodestr)
+          write (this%iout, fmtdry) trim(nodestr), DHDRY
+        end if
+      end if
+      !
+      ! -- Convert dry transport cell to active if flow has rewet
+      if (cnew(n) == DHDRY) then
+        if (this%gwfhead(n) /= DHDRY) then
+          !
+          ! -- obtain weighted concentration
+          crewet = DZERO
+          tflow = DZERO
+          do ipos = this%dis%con%ia(n) + 1, this%dis%con%ia(n + 1) - 1
+            m = this%dis%con%ja(ipos)
+            flownm = this%gwfflowja(ipos)
+            if (flownm > 0) then
+              if (this%ibound(m) /= 0) then
+                crewet = crewet + cnew(m) * flownm
+                tflow = tflow + this%gwfflowja(ipos)
+              end if
+            end if
+          end do
+          if (tflow > DZERO) then
+            crewet = crewet / tflow
+          else
+            crewet = DZERO
+          end if
+          !
+          ! -- cell is now wet
+          this%ibound(n) = 1
+          cnew(n) = crewet
+          call this%dis%noder_to_string(n, nodestr)
+          write (this%iout, fmtrewet) trim(nodestr), crewet
+        end if
+      end if
+    end do
+    !
+    ! -- Return
+    return
+  end subroutine fmi_ad
+
+  !> @brief Calculate coefficients and fill matrix and rhs terms associated
+  !! with FMI object
+  !<
+  subroutine fmi_fc(this, nodes, cold, nja, matrix_sln, idxglo, rhs)
+    ! -- dummy
+    class(TspFmiType) :: this
+    integer, intent(in) :: nodes
+    real(DP), intent(in), dimension(nodes) :: cold
+    integer(I4B), intent(in) :: nja
+    class(MatrixBaseType), pointer :: matrix_sln
+    integer(I4B), intent(in), dimension(nja) :: idxglo
+    real(DP), intent(inout), dimension(nodes) :: rhs
+    ! -- local
+    integer(I4B) :: n, idiag, idiag_sln
+    !
+    ! -- Calculate the flow imbalance error and make a correction for it
+    if (this%iflowerr /= 0) then
+      !
+      ! -- Correct the transport solution for the flow imbalance by adding
+      !    the flow residual to the diagonal
+      do n = 1, nodes
+        idiag = this%dis%con%ia(n)
+        idiag_sln = idxglo(idiag)
+        call matrix_sln%add_value_pos(idiag_sln, -this%gwfflowja(idiag))
+      end do
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine fmi_fc
+
+  !> @brief Calculate flow correction
+  !!
+  !! Where there is a flow imbalance for a given cell, a correction may be
+  !! applied if selected
+  !<
+  subroutine fmi_cq(this, cnew, flowja)
+    ! -- modules
+    ! -- dummy
+    class(TspFmiType) :: this
+    real(DP), intent(in), dimension(:) :: cnew
+    real(DP), dimension(:), contiguous, intent(inout) :: flowja
+    ! -- local
+    integer(I4B) :: n
+    integer(I4B) :: idiag
+    real(DP) :: rate
+    !
+    ! -- If not adding flow error correction, return
+    if (this%iflowerr /= 0) then
+      !
+      ! -- Accumulate the flow correction term
+      do n = 1, this%dis%nodes
+        rate = DZERO
+        idiag = this%dis%con%ia(n)
+        if (this%ibound(n) > 0) then
+          rate = -this%gwfflowja(idiag) * cnew(n) * this%eqnsclfac
+        end if
+        this%flowcorrect(n) = rate
+        flowja(idiag) = flowja(idiag) + rate
+      end do
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine fmi_cq
+
+  !> @brief Calculate budget terms associated with FMI object
+  !<
+  subroutine fmi_bd(this, isuppress_output, model_budget)
+    ! -- modules
+    use TdisModule, only: delt
+    use BudgetModule, only: BudgetType, rate_accumulator
+    ! -- dummy
+    class(TspFmiType) :: this
+    integer(I4B), intent(in) :: isuppress_output
+    type(BudgetType), intent(inout) :: model_budget
+    ! -- local
+    real(DP) :: rin
+    real(DP) :: rout
+    !
+    ! -- flow correction
+    if (this%iflowerr /= 0) then
+      call rate_accumulator(this%flowcorrect, rin, rout)
+      call model_budget%addentry(rin, rout, delt, budtxt(2), isuppress_output)
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine fmi_bd
+
+  !> @brief Save budget terms associated with FMI object
+  !<
+  subroutine fmi_ot_flow(this, icbcfl, icbcun)
+    ! -- dummy
+    class(TspFmiType) :: this
+    integer(I4B), intent(in) :: icbcfl
+    integer(I4B), intent(in) :: icbcun
+    ! -- local
+    integer(I4B) :: ibinun
+    integer(I4B) :: iprint, nvaluesp, nwidthp
+    character(len=1) :: cdatafmp = ' ', editdesc = ' '
+    real(DP) :: dinact
+    !
+    ! -- Set unit number for binary output
+    if (this%ipakcb < 0) then
+      ibinun = icbcun
+    elseif (this%ipakcb == 0) then
+      ibinun = 0
+    else
+      ibinun = this%ipakcb
+    end if
+    if (icbcfl == 0) ibinun = 0
+    !
+    ! -- Do not save flow corrections if not active
+    if (this%iflowerr == 0) ibinun = 0
+    !
+    ! -- Record the storage rates if requested
+    if (ibinun /= 0) then
+      iprint = 0
+      dinact = DZERO
+      !
+      ! -- flow correction
+      call this%dis%record_array(this%flowcorrect, this%iout, iprint, -ibinun, &
+                                 budtxt(2), cdatafmp, nvaluesp, &
+                                 nwidthp, editdesc, dinact)
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine fmi_ot_flow
+
+  !> @brief Deallocate variables
+  !!
+  !! Deallocate memory associated with FMI object
+  !<
+  subroutine gwtfmi_da(this)
+    ! -- modules
+    use MemoryManagerModule, only: mem_deallocate
+    ! -- dummy
+    class(TspFmiType) :: this
+    ! -- todo: finalize hfr and bfr either here or in a finalize routine
+    !
+    ! -- deallocate any memory stored with gwfpackages
+    call this%deallocate_gwfpackages()
+    !
+    ! -- deallocate fmi arrays
+    if (associated(this%datp)) then
+      deallocate (this%datp)
+      deallocate (this%gwfpackages)
+      deallocate (this%flowpacknamearray)
+      call mem_deallocate(this%iatp)
+      call mem_deallocate(this%igwfmvrterm)
+    end if
+
+    deallocate (this%aptbudobj)
+    call mem_deallocate(this%flowcorrect)
+    call mem_deallocate(this%ibdgwfsat0)
+    if (this%flows_from_file) then
+      call mem_deallocate(this%gwfstrgss)
+      call mem_deallocate(this%gwfstrgsy)
+    end if
+    !
+    ! -- special treatment, these could be from mem_checkin
+    call mem_deallocate(this%gwfhead, 'GWFHEAD', this%memoryPath)
+    call mem_deallocate(this%gwfsat, 'GWFSAT', this%memoryPath)
+    call mem_deallocate(this%gwfspdis, 'GWFSPDIS', this%memoryPath)
+    call mem_deallocate(this%gwfflowja, 'GWFFLOWJA', this%memoryPath)
+    !
+    ! -- deallocate scalars
+    call mem_deallocate(this%flows_from_file)
+    call mem_deallocate(this%iflowsupdated)
+    call mem_deallocate(this%iflowerr)
+    call mem_deallocate(this%igwfstrgss)
+    call mem_deallocate(this%igwfstrgsy)
+    call mem_deallocate(this%iubud)
+    call mem_deallocate(this%iuhds)
+    call mem_deallocate(this%iumvr)
+    call mem_deallocate(this%nflowpack)
+    !
+    ! -- deallocate parent
+    call this%NumericalPackageType%da()
+    !
+    ! -- Return
+    return
+  end subroutine gwtfmi_da
+
+  !> @ brief Allocate scalars
+  !!
+  !! Allocate scalar variables for an FMI object
+  !<
+  subroutine gwtfmi_allocate_scalars(this)
+    ! -- modules
+    use MemoryManagerModule, only: mem_allocate, mem_setptr
+    ! -- dummy
+    class(TspFmiType) :: this
+    ! -- local
+    !
+    ! -- allocate scalars in parent
+    call this%FlowModelInterfaceType%allocate_scalars()
+    !
+    ! -- Allocate
+    call mem_allocate(this%iflowerr, 'IFLOWERR', this%memoryPath)
+    !
+    ! -- Although not a scalar, allocate the advanced package transport
+    !    budget object to zero so that it can be dynamically resized later
+    allocate (this%aptbudobj(0))
+    !
+    ! -- Initialize
+    this%iflowerr = 0
+    !
+    ! -- Return
+    return
+  end subroutine gwtfmi_allocate_scalars
+
+  !> @ brief Allocate arrays for FMI object
+  !!
+  !!  Method to allocate arrays for the FMI package.
+  !<
+  subroutine gwtfmi_allocate_arrays(this, nodes)
+    use MemoryManagerModule, only: mem_allocate
+    ! -- modules
+    use ConstantsModule, only: DZERO
+    ! -- dummy
+    class(TspFmiType) :: this
+    integer(I4B), intent(in) :: nodes
+    ! -- local
+    integer(I4B) :: n
+    !
+    ! -- allocate parent arrays
+    call this%FlowModelInterfaceType%allocate_arrays(nodes)
+    !
+    ! -- Allocate variables needed for all cases
+    if (this%iflowerr == 0) then
+      call mem_allocate(this%flowcorrect, 1, 'FLOWCORRECT', this%memoryPath)
+    else
+      call mem_allocate(this%flowcorrect, nodes, 'FLOWCORRECT', this%memoryPath)
+    end if
+    do n = 1, size(this%flowcorrect)
+      this%flowcorrect(n) = DZERO
+    end do
+    !
+    ! -- return
+    return
+  end subroutine gwtfmi_allocate_arrays
+
+  !> @brief Calculate the previous saturation level
+  !!
+  !! Calculate the groundwater cell head saturation for the end of
+  !! the last time step
+  !<
+  function gwfsatold(this, n, delt) result(satold)
+    ! -- modules
+    ! -- dummy
+    class(TspFmiType) :: this
+    integer(I4B), intent(in) :: n
+    real(DP), intent(in) :: delt
+    ! -- result
+    real(DP) :: satold
+    ! -- local
+    real(DP) :: vcell
+    real(DP) :: vnew
+    real(DP) :: vold
+    !
+    ! -- calculate the value
+    vcell = this%dis%area(n) * (this%dis%top(n) - this%dis%bot(n))
+    vnew = vcell * this%gwfsat(n)
+    vold = vnew
+    if (this%igwfstrgss /= 0) vold = vold + this%gwfstrgss(n) * delt
+    if (this%igwfstrgsy /= 0) vold = vold + this%gwfstrgsy(n) * delt
+    satold = vold / vcell
+    !
+    ! -- Return
+    return
+  end function gwfsatold
+
+  !> @brief Read options from input file
+  !<
+  subroutine gwtfmi_read_options(this)
+    ! -- modules
+    use ConstantsModule, only: LINELENGTH, DEM6
+    use InputOutputModule, only: getunit, openfile, urdaux
+    use SimModule, only: store_error, store_error_unit
+    ! -- dummy
+    class(TspFmiType) :: this
+    ! -- local
+    character(len=LINELENGTH) :: keyword
+    integer(I4B) :: ierr
+    logical :: isfound, endOfBlock
+    character(len=*), parameter :: fmtisvflow = &
+      "(4x,'CELL-BY-CELL FLOW INFORMATION WILL BE SAVED TO BINARY FILE &
+      &WHENEVER ICBCFL IS NOT ZERO AND FLOW IMBALANCE CORRECTION ACTIVE.')"
+    character(len=*), parameter :: fmtifc = &
+      &"(4x,'MASS WILL BE ADDED OR REMOVED TO COMPENSATE FOR FLOW IMBALANCE.')"
+    !
+    ! -- get options block
+    call this%parser%GetBlock('OPTIONS', isfound, ierr, blockRequired=.false., &
+                              supportOpenClose=.true.)
+    !
+    ! -- parse options block if detected
+    if (isfound) then
+      write (this%iout, '(1x,a)') 'PROCESSING FMI OPTIONS'
+      do
+        call this%parser%GetNextLine(endOfBlock)
+        if (endOfBlock) exit
+        call this%parser%GetStringCaps(keyword)
+        select case (keyword)
+        case ('SAVE_FLOWS')
+          this%ipakcb = -1
+          write (this%iout, fmtisvflow)
+        case ('FLOW_IMBALANCE_CORRECTION')
+          write (this%iout, fmtifc)
+          this%iflowerr = 1
+        case default
+          write (errmsg, '(a,a)') 'Unknown FMI option: ', &
+            trim(keyword)
+          call store_error(errmsg)
+          call this%parser%StoreErrorUnit()
+        end select
+      end do
+      write (this%iout, '(1x,a)') 'END OF FMI OPTIONS'
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine gwtfmi_read_options
+
+  !> @brief Read PACKAGEDATA block
+  !!
+  !! Read packagedata block from input file
+  !<
+  subroutine gwtfmi_read_packagedata(this)
+    ! -- modules
+    use OpenSpecModule, only: ACCESS, FORM
+    use ConstantsModule, only: LINELENGTH, DEM6, LENPACKAGENAME
+    use InputOutputModule, only: getunit, openfile, urdaux
+    use SimModule, only: store_error, store_error_unit
+    ! -- dummy
+    class(TspFmiType) :: this
+    ! -- local
+    type(BudgetObjectType), pointer :: budobjptr
+    character(len=LINELENGTH) :: keyword, fname
+    character(len=LENPACKAGENAME) :: pname
+    integer(I4B) :: i
+    integer(I4B) :: ierr
+    integer(I4B) :: inunit
+    integer(I4B) :: iapt
+    logical :: isfound, endOfBlock
+    logical :: blockrequired
+    logical :: exist
+    type(BudObjPtrArray), dimension(:), allocatable :: tmpbudobj
+    !
+    ! -- initialize
+    iapt = 0
+    blockrequired = .true.
+    !
+    ! -- get options block
+    call this%parser%GetBlock('PACKAGEDATA', isfound, ierr, &
+                              blockRequired=blockRequired, &
+                              supportOpenClose=.true.)
+    !
+    ! -- parse options block if detected
+    if (isfound) then
+      write (this%iout, '(1x,a)') 'PROCESSING FMI PACKAGEDATA'
+      do
+        call this%parser%GetNextLine(endOfBlock)
+        if (endOfBlock) exit
+        call this%parser%GetStringCaps(keyword)
+        select case (keyword)
+        case ('GWFBUDGET')
+          call this%parser%GetStringCaps(keyword)
+          if (keyword /= 'FILEIN') then
+            call store_error('GWFBUDGET keyword must be followed by '// &
+                             '"FILEIN" then by filename.')
+            call this%parser%StoreErrorUnit()
+          end if
+          call this%parser%GetString(fname)
+          inunit = getunit()
+          inquire (file=trim(fname), exist=exist)
+          if (.not. exist) then
+            call store_error('Could not find file '//trim(fname))
+            call this%parser%StoreErrorUnit()
+          end if
+          call openfile(inunit, this%iout, fname, 'DATA(BINARY)', FORM, &
+                        ACCESS, 'UNKNOWN')
+          this%iubud = inunit
+          call this%initialize_bfr()
+        case ('GWFHEAD')
+          call this%parser%GetStringCaps(keyword)
+          if (keyword /= 'FILEIN') then
+            call store_error('GWFHEAD keyword must be followed by '// &
+                             '"FILEIN" then by filename.')
+            call this%parser%StoreErrorUnit()
+          end if
+          call this%parser%GetString(fname)
+          inquire (file=trim(fname), exist=exist)
+          if (.not. exist) then
+            call store_error('Could not find file '//trim(fname))
+            call this%parser%StoreErrorUnit()
+          end if
+          inunit = getunit()
+          call openfile(inunit, this%iout, fname, 'DATA(BINARY)', FORM, &
+                        ACCESS, 'UNKNOWN')
+          this%iuhds = inunit
+          call this%initialize_hfr()
+        case ('GWFMOVER')
+          call this%parser%GetStringCaps(keyword)
+          if (keyword /= 'FILEIN') then
+            call store_error('GWFMOVER keyword must be followed by '// &
+                             '"FILEIN" then by filename.')
+            call this%parser%StoreErrorUnit()
+          end if
+          call this%parser%GetString(fname)
+          inunit = getunit()
+          call openfile(inunit, this%iout, fname, 'DATA(BINARY)', FORM, &
+                        ACCESS, 'UNKNOWN')
+          this%iumvr = inunit
+          call budgetobject_cr_bfr(this%mvrbudobj, 'MVT', this%iumvr, &
+                                   this%iout)
+          call this%mvrbudobj%fill_from_bfr(this%dis, this%iout)
+        case default
+          !
+          ! --expand the size of aptbudobj, which stores a pointer to the budobj
+          allocate (tmpbudobj(iapt))
+          do i = 1, size(this%aptbudobj)
+            tmpbudobj(i)%ptr => this%aptbudobj(i)%ptr
+          end do
+          deallocate (this%aptbudobj)
+          allocate (this%aptbudobj(iapt + 1))
+          do i = 1, size(tmpbudobj)
+            this%aptbudobj(i)%ptr => tmpbudobj(i)%ptr
+          end do
+          deallocate (tmpbudobj)
+          !
+          ! -- Open the budget file and start filling it
+          iapt = iapt + 1
+          pname = keyword(1:LENPACKAGENAME)
+          call this%parser%GetStringCaps(keyword)
+          if (keyword /= 'FILEIN') then
+            call store_error('Package name must be followed by '// &
+                             '"FILEIN" then by filename.')
+            call this%parser%StoreErrorUnit()
+          end if
+          call this%parser%GetString(fname)
+          inunit = getunit()
+          call openfile(inunit, this%iout, fname, 'DATA(BINARY)', FORM, &
+                        ACCESS, 'UNKNOWN')
+          call budgetobject_cr_bfr(budobjptr, pname, inunit, &
+                                   this%iout, colconv2=['GWF             '])
+          call budobjptr%fill_from_bfr(this%dis, this%iout)
+          this%aptbudobj(iapt)%ptr => budobjptr
+        end select
+      end do
+      write (this%iout, '(1x,a)') 'END OF FMI PACKAGEDATA'
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine gwtfmi_read_packagedata
+
+  !> @brief Set the pointer to a budget object
+  !!
+  !! An advanced transport can pass in a name and a
+  !! pointer budget object, and this routine will look through the budget
+  !! objects managed by FMI and point to the one with the same name, such as
+  !! LAK-1, SFR-1, etc.
+  !<
+  subroutine set_aptbudobj_pointer(this, name, budobjptr)
+    ! -- modules
+    class(TspFmiType) :: this
+    ! -- dumm
+    character(len=*), intent(in) :: name
+    type(BudgetObjectType), pointer :: budobjptr
+    ! -- local
+    integer(I4B) :: i
+    !
+    ! -- find and set the pointer
+    do i = 1, size(this%aptbudobj)
+      if (this%aptbudobj(i)%ptr%name == name) then
+        budobjptr => this%aptbudobj(i)%ptr
+        exit
+      end if
+    end do
+    !
+    ! -- Return
+    return
+  end subroutine set_aptbudobj_pointer
+
+  !> @brief Initialize the groundwater flow terms based on the budget file
+  !! reader
+  !!
+  !! Initalize terms and figure out how many different terms and packages
+  !! are contained within the file
+  !<
+  subroutine initialize_gwfterms_from_bfr(this)
+    ! -- modules
+    use MemoryManagerModule, only: mem_allocate
+    use SimModule, only: store_error, store_error_unit, count_errors
+    ! -- dummy
+    class(TspFmiType) :: this
+    ! -- local
+    integer(I4B) :: nflowpack
+    integer(I4B) :: i, ip
+    integer(I4B) :: naux
+    logical :: found_flowja
+    logical :: found_dataspdis
+    logical :: found_datasat
+    logical :: found_stoss
+    logical :: found_stosy
+    integer(I4B), dimension(:), allocatable :: imap
+    !
+    ! -- Calculate the number of gwf flow packages
+    allocate (imap(this%bfr%nbudterms))
+    imap(:) = 0
+    nflowpack = 0
+    found_flowja = .false.
+    found_dataspdis = .false.
+    found_datasat = .false.
+    found_stoss = .false.
+    found_stosy = .false.
+    do i = 1, this%bfr%nbudterms
+      select case (trim(adjustl(this%bfr%budtxtarray(i))))
+      case ('FLOW-JA-FACE')
+        found_flowja = .true.
+      case ('DATA-SPDIS')
+        found_dataspdis = .true.
+      case ('DATA-SAT')
+        found_datasat = .true.
+      case ('STO-SS')
+        found_stoss = .true.
+        this%igwfstrgss = 1
+      case ('STO-SY')
+        found_stosy = .true.
+        this%igwfstrgsy = 1
+      case default
+        nflowpack = nflowpack + 1
+        imap(i) = 1
+      end select
+    end do
+    !
+    ! -- allocate gwfpackage arrays (gwfpackages, iatp, datp, ...)
+    call this%allocate_gwfpackages(nflowpack)
+    !
+    ! -- Copy the package name and aux names from budget file reader
+    !    to the gwfpackages derived-type variable
+    ip = 1
+    do i = 1, this%bfr%nbudterms
+      if (imap(i) == 0) cycle
+      call this%gwfpackages(ip)%set_name(this%bfr%dstpackagenamearray(i), &
+                                         this%bfr%budtxtarray(i))
+      naux = this%bfr%nauxarray(i)
+      call this%gwfpackages(ip)%set_auxname(naux, &
+                                            this%bfr%auxtxtarray(1:naux, i))
+      ip = ip + 1
+    end do
+    !
+    ! -- Copy just the package names for the boundary packages into
+    !    the flowpacknamearray
+    ip = 1
+    do i = 1, size(imap)
+      if (imap(i) == 1) then
+        this%flowpacknamearray(ip) = this%bfr%dstpackagenamearray(i)
+        ip = ip + 1
+      end if
+    end do
+    !
+    ! -- Error if specific discharge, saturation or flowja not found
+    if (.not. found_dataspdis) then
+      write (errmsg, '(a)') 'Specific discharge not found in &
+                            &budget file. SAVE_SPECIFIC_DISCHARGE and &
+                            &SAVE_FLOWS must be activated in the NPF package.'
+      call store_error(errmsg)
+    end if
+    if (.not. found_datasat) then
+      write (errmsg, '(a)') 'Saturation not found in &
+                            &budget file. SAVE_SATURATION and &
+                            &SAVE_FLOWS must be activated in the NPF package.'
+      call store_error(errmsg)
+    end if
+    if (.not. found_flowja) then
+      write (errmsg, '(a)') 'FLOWJA not found in &
+                            &budget file. SAVE_FLOWS must &
+                            &be activated in the NPF package.'
+      call store_error(errmsg)
+    end if
+    if (count_errors() > 0) then
+      call this%parser%StoreErrorUnit()
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine initialize_gwfterms_from_bfr
+
+  !> @brief Initialize groundwater flow terms from the groundwater budget
+  !!
+  !! Flows are coming from a gwf-gwt exchange object
+  !<
+  subroutine initialize_gwfterms_from_gwfbndlist(this)
+    ! -- modules
+    use BndModule, only: BndType, GetBndFromList
+    ! -- dummy
+    class(TspFmiType) :: this
+    ! -- local
+    integer(I4B) :: ngwfpack
+    integer(I4B) :: ngwfterms
+    integer(I4B) :: ip
+    integer(I4B) :: imover
+    integer(I4B) :: ntomvr
+    integer(I4B) :: iterm
+    character(len=LENPACKAGENAME) :: budtxt
+    class(BndType), pointer :: packobj => null()
+    !
+    ! -- determine size of gwf terms
+    ngwfpack = this%gwfbndlist%Count()
+    !
+    ! -- Count number of to-mvr terms, but do not include advanced packages
+    !    as those mover terms are not losses from the cell, but rather flows
+    !    within the advanced package
+    ntomvr = 0
+    do ip = 1, ngwfpack
+      packobj => GetBndFromList(this%gwfbndlist, ip)
+      imover = packobj%imover
+      if (packobj%isadvpak /= 0) imover = 0
+      if (imover /= 0) then
+        ntomvr = ntomvr + 1
+      end if
+    end do
+    !
+    ! -- Allocate arrays in fmi of size ngwfterms, which is the number of
+    !    packages plus the number of packages with mover terms.
+    ngwfterms = ngwfpack + ntomvr
+    call this%allocate_gwfpackages(ngwfterms)
+    !
+    ! -- Assign values in the fmi package
+    iterm = 1
+    do ip = 1, ngwfpack
+      !
+      ! -- set and store names
+      packobj => GetBndFromList(this%gwfbndlist, ip)
+      budtxt = adjustl(packobj%text)
+      call this%gwfpackages(iterm)%set_name(packobj%packName, budtxt)
+      this%flowpacknamearray(iterm) = packobj%packName
+      call this%gwfpackages(iterm)%set_auxname(packobj%naux, &
+                                               packobj%auxname)
+      iterm = iterm + 1
+      !
+      ! -- if this package has a mover associated with it, then add another
+      !    term that corresponds to the mover flows
+      imover = packobj%imover
+      if (packobj%isadvpak /= 0) imover = 0
+      if (imover /= 0) then
+        budtxt = trim(adjustl(packobj%text))//'-TO-MVR'
+        call this%gwfpackages(iterm)%set_name(packobj%packName, budtxt)
+        this%flowpacknamearray(iterm) = packobj%packName
+        call this%gwfpackages(iterm)%set_auxname(packobj%naux, &
+                                                 packobj%auxname)
+        this%igwfmvrterm(iterm) = 1
+        iterm = iterm + 1
+      end if
+    end do
+    !
+    ! -- Return
+    return
+  end subroutine initialize_gwfterms_from_gwfbndlist
+
+  !> @brief Initialize an array for storing PackageBudget objects.
+  !!
+  !! This routine allocates gwfpackages (an array of PackageBudget
+  !! objects) to the proper size and initializes member variables.
+  !<
+  subroutine gwtfmi_allocate_gwfpackages(this, ngwfterms)
+    ! -- modules
+    use ConstantsModule, only: LENMEMPATH
+    use MemoryManagerModule, only: mem_allocate
+    ! -- dummy
+    class(TspFmiType) :: this
+    integer(I4B), intent(in) :: ngwfterms
+    ! -- local
+    integer(I4B) :: n
+    character(len=LENMEMPATH) :: memPath
+    !
+    ! -- direct allocate
+    allocate (this%gwfpackages(ngwfterms))
+    allocate (this%flowpacknamearray(ngwfterms))
+    allocate (this%datp(ngwfterms))
+    !
+    ! -- mem_allocate
+    call mem_allocate(this%iatp, ngwfterms, 'IATP', this%memoryPath)
+    call mem_allocate(this%igwfmvrterm, ngwfterms, 'IGWFMVRTERM', this%memoryPath)
+    !
+    ! -- initialize
+    this%nflowpack = ngwfterms
+    do n = 1, this%nflowpack
+      this%iatp(n) = 0
+      this%igwfmvrterm(n) = 0
+      this%flowpacknamearray(n) = ''
+      !
+      ! -- Create a mempath for each individual flow package data set
+      !    of the form, MODELNAME/FMI-FTn
+      write (memPath, '(a, i0)') trim(this%memoryPath)//'-FT', n
+      call this%gwfpackages(n)%initialize(memPath)
+    end do
+    !
+    ! -- Return
+    return
+  end subroutine gwtfmi_allocate_gwfpackages
+
+  !> @brief Deallocate memory
+  !!
+  !! Deallocate memory that stores the gwfpackages array
+  !<
+  subroutine gwtfmi_deallocate_gwfpackages(this)
+    ! -- modules
+    ! -- dummy
+    class(TspFmiType) :: this
+    ! -- local
+    integer(I4B) :: n
+    !
+    ! -- initialize
+    do n = 1, this%nflowpack
+      call this%gwfpackages(n)%da()
+    end do
+    !
+    ! -- Return
+    return
+  end subroutine gwtfmi_deallocate_gwfpackages
+
+end module TspFmiModule
diff --git a/src/Model/TransportModel/tsp1ic1.f90 b/src/Model/TransportModel/tsp1ic1.f90
new file mode 100644
index 00000000000..e36ca15a88e
--- /dev/null
+++ b/src/Model/TransportModel/tsp1ic1.f90
@@ -0,0 +1,53 @@
+module TspIcModule
+
+  use KindModule, only: DP, I4B
+  use ConstantsModule, only: LENVARNAME
+  use GwfIcModule, only: GwfIcType
+  use BlockParserModule, only: BlockParserType
+  use BaseDisModule, only: DisBaseType
+
+  implicit none
+  private
+  public :: TspIcType
+  public :: ic_cr
+
+  ! -- Most of the TspIcType functionality comes from GwfIcType
+  type, extends(GwfIcType) :: TspIcType
+    ! -- strings
+    character(len=LENVARNAME) :: depvartype = ''
+  end type TspIcType
+
+contains
+
+  !> @brief Create a new initial conditions object
+  !<
+  subroutine ic_cr(ic, name_model, input_mempath, inunit, iout, dis, depvartype)
+    ! -- dummy
+    type(TspIcType), pointer :: ic
+    character(len=*), intent(in) :: name_model
+    character(len=*), intent(in) :: input_mempath
+    integer(I4B), intent(in) :: inunit
+    integer(I4B), intent(in) :: iout
+    class(DisBaseType), pointer, intent(in) :: dis
+    character(len=LENVARNAME), intent(in) :: depvartype
+    !
+    ! -- Create the object
+    allocate (ic)
+    !
+    ! -- create name and memory path
+    call ic%set_names(1, name_model, 'IC', 'IC', input_mempath)
+    !
+    ! -- Allocate scalars
+    call ic%allocate_scalars()
+    !
+    ic%inunit = inunit
+    ic%iout = iout
+    !
+    ! -- set pointers
+    ic%dis => dis
+    !
+    ! -- Give package access to the assigned labelsd based on dependent variable
+    ic%depvartype = depvartype
+  end subroutine ic_cr
+
+end module TspIcModule
diff --git a/src/Model/GroundWaterTransport/gwt1mvt1.f90 b/src/Model/TransportModel/tsp1mvt1.f90
similarity index 78%
rename from src/Model/GroundWaterTransport/gwt1mvt1.f90
rename to src/Model/TransportModel/tsp1mvt1.f90
index 732b2e59ac3..a0b1530dc80 100644
--- a/src/Model/GroundWaterTransport/gwt1mvt1.f90
+++ b/src/Model/TransportModel/tsp1mvt1.f90
@@ -2,7 +2,7 @@
 ! -- This module is responsible for sending mass from providers into
 ! -- receiver qmfrommvr arrays and writing a mover transport budget
 
-module GwtMvtModule
+module TspMvtModule
 
   use KindModule, only: DP, I4B
   use ConstantsModule, only: LINELENGTH, MAXCHARLEN, DZERO, LENPAKLOC, &
@@ -11,7 +11,7 @@ module GwtMvtModule
   use SimModule, only: store_error
   use BaseDisModule, only: DisBaseType
   use NumericalPackageModule, only: NumericalPackageType
-  use GwtFmiModule, only: GwtFmiType
+  use TspFmiModule, only: TspFmiType
   use BudgetModule, only: BudgetType, budget_cr
   use BudgetObjectModule, only: BudgetObjectType, budgetobject_cr
   use TableModule, only: TableType, table_cr
@@ -19,17 +19,18 @@ module GwtMvtModule
   implicit none
 
   private
-  public :: GwtMvtType
+  public :: TspMvtType
   public :: mvt_cr
 
-  type, extends(NumericalPackageType) :: GwtMvtType
+  type, extends(NumericalPackageType) :: TspMvtType
     character(len=LENMODELNAME) :: gwfmodelname1 = '' !< name of model 1
     character(len=LENMODELNAME) :: gwfmodelname2 = '' !< name of model 2 (set to modelname 1 for single model MVT)
     integer(I4B), pointer :: maxpackages !< max number of packages
     integer(I4B), pointer :: ibudgetout => null() !< unit number for budget output file
     integer(I4B), pointer :: ibudcsv => null() !< unit number for csv budget output file
-    type(GwtFmiType), pointer :: fmi1 => null() !< pointer to fmi object for model 1
-    type(GwtFmiType), pointer :: fmi2 => null() !< pointer to fmi object for model 2 (set to fmi1 for single model)
+    real(DP), pointer :: eqnsclfac => null() !< governing equation scale factor; =1. for solute; =rhow*cpw for energy
+    type(TspFmiType), pointer :: fmi1 => null() !< pointer to fmi object for model 1
+    type(TspFmiType), pointer :: fmi2 => null() !< pointer to fmi object for model 2 (set to fmi1 for single model)
     type(BudgetType), pointer :: budget => null() !< mover transport budget object (used to write balance table)
     type(BudgetObjectType), pointer :: budobj => null() !< budget container (used to write binary file)
     type(BudgetObjectType), pointer :: mvrbudobj => null() !< pointer to the water mover budget object
@@ -58,27 +59,24 @@ module GwtMvtModule
     procedure :: set_fmi_pr_rc
     procedure, private :: mvt_setup_outputtab
     procedure, private :: mvt_print_outputtab
-  end type GwtMvtType
+  end type TspMvtType
 
 contains
 
-  subroutine mvt_cr(mvt, name_model, inunit, iout, fmi1, gwfmodelname1, &
-                    gwfmodelname2, fmi2)
-! ******************************************************************************
-! mvt_cr -- Create a new initial conditions object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Create a new mover transport object
+  !<
+  subroutine mvt_cr(mvt, name_model, inunit, iout, fmi1, eqnsclfac, &
+                    gwfmodelname1, gwfmodelname2, fmi2)
     ! -- dummy
-    type(GwtMvtType), pointer :: mvt
+    type(TspMvtType), pointer :: mvt
     character(len=*), intent(in) :: name_model
     integer(I4B), intent(in) :: inunit
     integer(I4B), intent(in) :: iout
-    type(GwtFmiType), intent(in), target :: fmi1
+    type(TspFmiType), intent(in), target :: fmi1
+    real(DP), intent(in), pointer :: eqnsclfac !< governing equation scale factor
     character(len=*), intent(in), optional :: gwfmodelname1
     character(len=*), intent(in), optional :: gwfmodelname2
-    type(GwtFmiType), intent(in), target, optional :: fmi2
+    type(TspFmiType), intent(in), target, optional :: fmi2
 ! ------------------------------------------------------------------------------
     !
     ! -- Create the object
@@ -113,20 +111,19 @@ subroutine mvt_cr(mvt, name_model, inunit, iout, fmi1, gwfmodelname1, &
     ! -- create the budget object
     call budgetobject_cr(mvt%budobj, 'TRANSPORT MOVER')
     !
+    ! -- Store pointer to governing equation scale factor
+    mvt%eqnsclfac => eqnsclfac
+    !
     ! -- Return
     return
   end subroutine mvt_cr
 
+  !> @brief Define mover transport object
+  !<
   subroutine mvt_df(this, dis)
-! ******************************************************************************
-! mvt_df -- Define
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtMvtType) :: this
+    class(TspMvtType) :: this
     class(DisBaseType), pointer, intent(in) :: dis
     ! -- local
     ! -- formats
@@ -162,21 +159,17 @@ end subroutine mvt_df
   !!
   !<
   subroutine set_pointer_mvrbudobj(this, mvrbudobj)
-    class(GwtMvtType) :: this
+    class(TspMvtType) :: this
     type(BudgetObjectType), intent(in), target :: mvrbudobj
     this%mvrbudobj => mvrbudobj
   end subroutine set_pointer_mvrbudobj
 
+  !> @brief Allocate and read mover-for-transport information
+  !<
   subroutine mvt_ar(this)
-! ******************************************************************************
-! mvt_ar -- Allocate and read water mover information
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtMvtType) :: this
+    class(TspMvtType) :: this
     ! -- locals
 ! ------------------------------------------------------------------------------
     !
@@ -187,17 +180,13 @@ subroutine mvt_ar(this)
     return
   end subroutine mvt_ar
 
+  !> @brief Read and prepare mover transport object
+  !<
   subroutine mvt_rp(this)
-! ******************************************************************************
-! mvt_rp -- Read and prepare
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: kper, kstp
     ! -- dummy
-    class(GwtMvtType) :: this
+    class(TspMvtType) :: this
     ! -- local
     ! -- formats
 ! ------------------------------------------------------------------------------
@@ -224,22 +213,18 @@ subroutine mvt_rp(this)
     return
   end subroutine mvt_rp
 
+  !> @brief Calculate coefficients and fill amat and rhs
+  !!
+  !! The mvt package adds the mass flow rate to the provider qmfrommvr array.
+  !! The advanced packages know enough to subract any mass that is leaving, so
+  !! the mvt just adds mass coming in from elsewhere.  Because the movers
+  !! change by stress period, their solute effects must be added to the right-
+  !! hand side of the transport matrix equations.
+  !<
   subroutine mvt_fc(this, cnew1, cnew2)
-! ******************************************************************************
-! mvt_fc -- Calculate coefficients and fill amat and rhs
-!
-!   The mvt package adds the mass flow rate to the provider qmfrommvr
-!   array.  The advanced packages know enough to subract any mass that is
-!   leaving, so the mvt just adds mass coming in from elsewhere.  Because the
-!   movers change change by stress period, their solute effects must be
-!   added to the right-hand side of the gwt matrix equations.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtMvtType) :: this
+    class(TspMvtType) :: this
     real(DP), intent(in), dimension(:), contiguous, target :: cnew1
     real(DP), intent(in), dimension(:), contiguous, target :: cnew2
     ! -- local
@@ -251,8 +236,8 @@ subroutine mvt_fc(this, cnew1, cnew2)
     real(DP) :: q, cp
     real(DP), dimension(:), pointer :: concpak
     real(DP), dimension(:), contiguous, pointer :: cnew
-    type(GwtFmiType), pointer :: fmi_pr !< pointer to provider model fmi package
-    type(GwtFmiType), pointer :: fmi_rc !< pointer to receiver model fmi package
+    type(TspFmiType), pointer :: fmi_pr !< pointer to provider model fmi package
+    type(TspFmiType), pointer :: fmi_rc !< pointer to receiver model fmi package
 ! ------------------------------------------------------------------------------
     !
     ! -- Add mover QC terms to the receiver packages
@@ -313,7 +298,7 @@ subroutine mvt_fc(this, cnew1, cnew2)
           !    water into the same receiver
           if (fmi_rc%iatp(irc) /= 0) then
             fmi_rc%datp(irc)%qmfrommvr(id2) = fmi_rc%datp(irc)%qmfrommvr(id2) - &
-                                              q * cp
+                                              q * cp * this%eqnsclfac
           end if
         end do
       end if
@@ -325,20 +310,19 @@ end subroutine mvt_fc
 
   !> @ brief Set the fmi_pr and fmi_rc pointers
   !!
-  !! The fmi_pr and fmi_rc arguments are pointers to the provider
-  !! and receiver FMI Packages.  If this MVT Package is owned by
-  !! a single GWT model, then these pointers are both set to the
-  !! FMI Package of this GWT model's FMI Package.  If this MVT
-  !! Package is owned by a GWTGWT Exchange, then the fmi_pr and
-  !! fmi_rc pointers may be assigned to FMI Packages in different models.
-  !!
+  !! The fmi_pr and fmi_rc arguments are pointers to the provider and receiver
+  !! FMI Packages.  If this MVT Package is owned by a single GWT model, then
+  !! these pointers are both set to the FMI Package of this GWT model's FMI
+  !! package.  If this MVT package is owned by a GWTGWT exchange, then the
+  !! fmi_pr and fmi_rc pointers may be assigned to FMI Packages in different
+  !! models.
   !<
   subroutine set_fmi_pr_rc(this, ibudterm, fmi_pr, fmi_rc)
     ! -- dummy
-    class(GwtMvtType) :: this
+    class(TspMvtType) :: this
     integer(I4B), intent(in) :: ibudterm
-    type(GwtFmiType), pointer :: fmi_pr
-    type(GwtFmiType), pointer :: fmi_rc
+    type(TspFmiType), pointer :: fmi_pr
+    type(TspFmiType), pointer :: fmi_rc
 
     fmi_pr => null()
     fmi_rc => null()
@@ -389,19 +373,16 @@ subroutine set_fmi_pr_rc(this, ibudterm, fmi_pr, fmi_rc)
       print *, 'Could not find FMI Package...'
       stop "error in set_fmi_pr_rc"
     end if
-
+    !
+    ! -- Return
     return
   end subroutine set_fmi_pr_rc
 
+  !> @brief Extra convergence check for mover
+  !<
   subroutine mvt_cc(this, kiter, iend, icnvgmod, cpak, dpak)
-! ******************************************************************************
-! mvt_cc -- extra convergence check for mover
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
-    class(GwtMvtType) :: this
+    class(TspMvtType) :: this
     integer(I4B), intent(in) :: kiter
     integer(I4B), intent(in) :: iend
     integer(I4B), intent(in) :: icnvgmod
@@ -412,7 +393,6 @@ subroutine mvt_cc(this, kiter, iend, icnvgmod, cpak, dpak)
     character(len=*), parameter :: fmtmvrcnvg = &
       "(/,1x,'MOVER PACKAGE REQUIRES AT LEAST TWO OUTER ITERATIONS. CONVERGE &
       &FLAG HAS BEEN RESET TO FALSE.')"
-! ------------------------------------------------------------------------------
     !
     ! -- If there are active movers, then at least 2 outers required
     if (associated(this%mvrbudobj)) then
@@ -427,16 +407,12 @@ subroutine mvt_cc(this, kiter, iend, icnvgmod, cpak, dpak)
     return
   end subroutine mvt_cc
 
+  !> @brief Write mover terms to listing file
+  !<
   subroutine mvt_bd(this, cnew1, cnew2)
-! ******************************************************************************
-! mvt_bd -- Write mover terms to listing file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtMvtType) :: this
+    class(TspMvtType) :: this
     real(DP), dimension(:), contiguous, intent(in) :: cnew1
     real(DP), dimension(:), contiguous, intent(in) :: cnew2
     ! -- local
@@ -449,17 +425,13 @@ subroutine mvt_bd(this, cnew1, cnew2)
     return
   end subroutine mvt_bd
 
+  !> @brief Write mover budget terms
+  !<
   subroutine mvt_ot_saveflow(this, icbcfl, ibudfl)
-! ******************************************************************************
-! mvt_bd -- Write mover terms
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: kstp, kper, delt, pertim, totim
     ! -- dummy
-    class(GwtMvttype) :: this
+    class(TspMvttype) :: this
     integer(I4B), intent(in) :: icbcfl
     integer(I4B), intent(in) :: ibudfl
     ! -- locals
@@ -481,16 +453,12 @@ subroutine mvt_ot_saveflow(this, icbcfl, ibudfl)
     return
   end subroutine mvt_ot_saveflow
 
+  !> @brief Print mover flow table
+  !<
   subroutine mvt_ot_printflow(this, icbcfl, ibudfl)
-! ******************************************************************************
-! mvr_ot_printflow -- Print mover flow table
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtMvtType) :: this
+    class(TspMvtType) :: this
     integer(I4B), intent(in) :: icbcfl
     integer(I4B), intent(in) :: ibudfl
     ! -- locals
@@ -505,18 +473,14 @@ subroutine mvt_ot_printflow(this, icbcfl, ibudfl)
     return
   end subroutine mvt_ot_printflow
 
+  !> @brief Write mover budget to listing file
+  !<
   subroutine mvt_ot_bdsummary(this, ibudfl)
-! ******************************************************************************
-! mvt_ot_bdsummary -- Write mover budget to listing file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: kstp, kper, delt, totim
     use ArrayHandlersModule, only: ifind, expandarray
     ! -- dummy
-    class(GwtMvtType) :: this
+    class(TspMvtType) :: this
     integer(I4B), intent(in) :: ibudfl
     ! -- locals
     integer(I4B) :: i, j, n
@@ -582,17 +546,15 @@ subroutine mvt_ot_bdsummary(this, ibudfl)
     return
   end subroutine mvt_ot_bdsummary
 
+  !> @ brief Deallocate memory
+  !!
+  !!  Method to deallocate memory for the package.
+  !<
   subroutine mvt_da(this)
-! ******************************************************************************
-! mvt_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
-    class(GwtMvtType) :: this
+    class(TspMvtType) :: this
     ! -- local
 ! ------------------------------------------------------------------------------
     !
@@ -634,17 +596,15 @@ subroutine mvt_da(this)
     return
   end subroutine mvt_da
 
+  !> @ brief Allocate scalar variables for package
+  !!
+  !!  Method to allocate scalar variables for the MVT package.
+  !<
   subroutine allocate_scalars(this)
-! ******************************************************************************
-! allocate_scalars
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate, mem_setptr
     ! -- dummy
-    class(GwtMvtType) :: this
+    class(TspMvtType) :: this
     ! -- local
 ! ------------------------------------------------------------------------------
     !
@@ -665,18 +625,14 @@ subroutine allocate_scalars(this)
     return
   end subroutine allocate_scalars
 
+  !> @brief Read mover-for-transport options block
+  !<
   subroutine read_options(this)
-! ******************************************************************************
-! read_options -- Read Options
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use OpenSpecModule, only: access, form
     use InputOutputModule, only: getunit, openfile
     ! -- dummy
-    class(GwtMvtType) :: this
+    class(TspMvtType) :: this
     ! -- local
     character(len=LINELENGTH) :: errmsg, keyword
     character(len=MAXCHARLEN) :: fname
@@ -751,17 +707,13 @@ subroutine read_options(this)
     return
   end subroutine read_options
 
+  !> @brief Set up the budget object that stores all the mvr flows
+  !<
   subroutine mvt_setup_budobj(this)
-! ******************************************************************************
-! mvt_setup_budobj -- Set up the budget object that stores all the mvr flows
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LENBUDTXT
     ! -- dummy
-    class(GwtMvtType) :: this
+    class(TspMvtType) :: this
     ! -- local
     integer(I4B) :: nbudterm
     integer(I4B) :: ncv
@@ -798,27 +750,22 @@ subroutine mvt_setup_budobj(this)
                                              maxlist, .false., .false., &
                                              naux)
     end do
-
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine mvt_setup_budobj
 
+  !> @brief Copy mover-for-transport flow terms into this%budobj
+  !<
   subroutine mvt_fill_budobj(this, cnew1, cnew2)
-! ******************************************************************************
-! mvt_fill_budobj -- copy flow terms into this%budobj
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     ! -- dummy
-    class(GwtMvtType) :: this
+    class(TspMvtType) :: this
     real(DP), intent(in), dimension(:), contiguous, target :: cnew1
     real(DP), intent(in), dimension(:), contiguous, target :: cnew2
     ! -- local
-    type(GwtFmiType), pointer :: fmi_pr
-    type(GwtFmiType), pointer :: fmi_rc
+    type(TspFmiType), pointer :: fmi_pr
+    type(TspFmiType), pointer :: fmi_rc
     real(DP), dimension(:), contiguous, pointer :: cnew
     integer(I4B) :: nbudterm
     integer(I4B) :: nlist
@@ -864,7 +811,7 @@ subroutine mvt_fill_budobj(this, cnew1, cnew2)
         ! -- Calculate solute mover rate
         rate = DZERO
         if (fmi_rc%iatp(irc) /= 0) then
-          rate = -q * cp
+          rate = -q * cp * this%eqnsclfac
         end if
         !
         ! -- add the rate to the budterm
@@ -879,21 +826,18 @@ subroutine mvt_fill_budobj(this, cnew1, cnew2)
     return
   end subroutine mvt_fill_budobj
 
+  !> @brief Determine max number of packages in use
+  !!
+  !! Scan through the gwf water mover budget object and determine the maximum
+  !! number of packages and unique package names
+  !<
   subroutine mvt_scan_mvrbudobj(this)
-! ******************************************************************************
-! mvt_scan_mvrbudobj -- scan through the gwf water mover budget object and
-!   determine the maximum number of packages and unique package names
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    class(GwtMvtType) :: this
+    class(TspMvtType) :: this
     integer(I4B) :: nbudterm
     integer(I4B) :: maxpackages
     integer(I4B) :: i, j
     integer(I4B) :: ipos
     logical :: found
-! ------------------------------------------------------------------------------
     !
     ! -- Calculate maxpackages, which is the the square of nbudterm
     nbudterm = this%mvrbudobj%nbudterm
@@ -931,22 +875,17 @@ subroutine mvt_scan_mvrbudobj(this)
     return
   end subroutine mvt_scan_mvrbudobj
 
+  !> @brief Set up the mover-for-transport output table
+  !<
   subroutine mvt_setup_outputtab(this)
-! ******************************************************************************
-! mvt_setup_outputtab -- set up output table
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
-    class(GwtMvtType), intent(inout) :: this
+    class(TspMvtType), intent(inout) :: this
     ! -- local
     character(len=LINELENGTH) :: title
     character(len=LINELENGTH) :: text
     integer(I4B) :: ntabcol
     integer(I4B) :: maxrow
     integer(I4B) :: ilen
-! ------------------------------------------------------------------------------
     !
     ! -- allocate and initialize the output table
     if (this%iprflow /= 0) then
@@ -984,17 +923,13 @@ subroutine mvt_setup_outputtab(this)
     return
   end subroutine mvt_setup_outputtab
 
+  !> @brief Set up mover-for-transport output table
+  !<
   subroutine mvt_print_outputtab(this)
-! ******************************************************************************
-! mvt_print_outputtab -- set up output table
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- module
     use TdisModule, only: kstp, kper
     ! -- dummy
-    class(GwtMvttype), intent(inout) :: this
+    class(TspMvttype), intent(inout) :: this
     ! -- local
     character(len=LINELENGTH) :: title
     character(len=LENMODELNAME + LENPACKAGENAME + 1) :: cloc1, cloc2
@@ -1045,5 +980,5 @@ subroutine mvt_print_outputtab(this)
     return
   end subroutine mvt_print_outputtab
 
-end module GwtMvtModule
+end module TspMvtModule
 
diff --git a/src/Model/GroundWaterTransport/gwt1obs1.f90 b/src/Model/TransportModel/tsp1obs1.f90
similarity index 54%
rename from src/Model/GroundWaterTransport/gwt1obs1.f90
rename to src/Model/TransportModel/tsp1obs1.f90
index 48dd58f0e7c..55e4114bf0a 100644
--- a/src/Model/GroundWaterTransport/gwt1obs1.f90
+++ b/src/Model/TransportModel/tsp1obs1.f90
@@ -1,9 +1,9 @@
-module GwtObsModule
+module TspObsModule
 
   use KindModule, only: DP, I4B
   use ConstantsModule, only: LINELENGTH, MAXOBSTYPES
   use BaseDisModule, only: DisBaseType
-  use GwtIcModule, only: GwtIcType
+  use TspIcModule, only: TspIcType
   use ObserveModule, only: ObserveType
   use ObsModule, only: ObsType
   use SimModule, only: count_errors, store_error, &
@@ -11,40 +11,37 @@ module GwtObsModule
   implicit none
 
   private
-  public :: GwtObsType, gwt_obs_cr
+  public :: TspObsType, tsp_obs_cr
 
-  type, extends(ObsType) :: GwtObsType
+  type, extends(ObsType) :: TspObsType
     ! -- Private members
-    type(GwtIcType), pointer, private :: ic => null() ! initial conditions
+    type(TspIcType), pointer, private :: ic => null() ! initial conditions
     real(DP), dimension(:), pointer, contiguous, private :: x => null() ! concentration
     real(DP), dimension(:), pointer, contiguous, private :: flowja => null() ! intercell flows
   contains
     ! -- Public procedures
-    procedure, public :: gwt_obs_ar
-    procedure, public :: obs_bd => gwt_obs_bd
-    procedure, public :: obs_df => gwt_obs_df
-    procedure, public :: obs_rp => gwt_obs_rp
-    procedure, public :: obs_da => gwt_obs_da
+    procedure, public :: tsp_obs_ar
+    procedure, public :: obs_bd => tsp_obs_bd
+    procedure, public :: obs_df => tsp_obs_df
+    procedure, public :: obs_rp => tsp_obs_rp
+    procedure, public :: obs_da => tsp_obs_da
     ! -- Private procedures
     procedure, private :: set_pointers
-  end type GwtObsType
+  end type TspObsType
 
 contains
 
-  subroutine gwt_obs_cr(obs, inobs)
-! ******************************************************************************
-! gwt_obs_cr -- Create a new GwtObsType object
-! Subroutine: (1) creates object
-!             (2) allocates pointers
-!             (3) initializes values
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Create a new TspObsType object
+  !!
+  !! This routine:
+  !!   - creates an observation object
+  !!   - allocates pointers
+  !!   - initializes values
+  !<
+  subroutine tsp_obs_cr(obs, inobs)
     ! -- dummy
-    type(GwtObsType), pointer, intent(out) :: obs
+    type(TspObsType), pointer, intent(out) :: obs
     integer(I4B), pointer, intent(in) :: inobs
-! ------------------------------------------------------------------------------
     !
     allocate (obs)
     call obs%allocate_scalars()
@@ -52,22 +49,20 @@ subroutine gwt_obs_cr(obs, inobs)
     obs%inputFilename = ''
     obs%inUnitObs => inobs
     !
+    ! -- Return
     return
-  end subroutine gwt_obs_cr
+  end subroutine tsp_obs_cr
 
-  subroutine gwt_obs_ar(this, ic, x, flowja)
-! ******************************************************************************
-! gwt_obs_ar -- allocate and read
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Allocate and read method for package
+  !!
+  !!  Method to allocate and read static data for the package.
+  !<
+  subroutine tsp_obs_ar(this, ic, x, flowja)
     ! -- dummy
-    class(GwtObsType), intent(inout) :: this
-    type(GwtIcType), pointer, intent(in) :: ic
+    class(TspObsType), intent(inout) :: this
+    type(TspIcType), pointer, intent(in) :: ic
     real(DP), dimension(:), pointer, contiguous, intent(in) :: x
     real(DP), dimension(:), pointer, contiguous, intent(in) :: flowja
-! ------------------------------------------------------------------------------
     !
     ! Call ar method of parent class
     call this%obs_ar()
@@ -75,25 +70,21 @@ subroutine gwt_obs_ar(this, ic, x, flowja)
     ! set pointers
     call this%set_pointers(ic, x, flowja)
     !
+    ! -- Return
     return
-  end subroutine gwt_obs_ar
+  end subroutine tsp_obs_ar
 
-  subroutine gwt_obs_df(this, iout, pkgname, filtyp, dis)
-! ******************************************************************************
-! gwt_obs_df -- define
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Define observation object
+  !<
+  subroutine tsp_obs_df(this, iout, pkgname, filtyp, dis)
     ! -- dummy
-    class(GwtObsType), intent(inout) :: this
+    class(TspObsType), intent(inout) :: this
     integer(I4B), intent(in) :: iout
     character(len=*), intent(in) :: pkgname
     character(len=*), intent(in) :: filtyp
     class(DisBaseType), pointer :: dis
     ! -- local
     integer(I4B) :: indx
-! ------------------------------------------------------------------------------
     !
     ! Call overridden method of parent class
     call this%ObsType%obs_df(iout, pkgname, filtyp, dis)
@@ -107,25 +98,21 @@ subroutine gwt_obs_df(this, iout, pkgname, filtyp, dis)
     !
     ! -- Store obs type and assign procedure pointer for flow-ja-face observation type
     call this%StoreObsType('flow-ja-face', .true., indx)
-    this%obsData(indx)%ProcessIdPtr => gwt_process_intercell_obs_id
+    this%obsData(indx)%ProcessIdPtr => tsp_process_intercell_obs_id
     !
+    ! -- Return
     return
-  end subroutine gwt_obs_df
+  end subroutine tsp_obs_df
 
-  subroutine gwt_obs_bd(this)
-! ******************************************************************************
-! gwt_obs_bd -- save obs
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Save observations
+  !<
+  subroutine tsp_obs_bd(this)
     ! -- dummy
-    class(GwtObsType), intent(inout) :: this
+    class(TspObsType), intent(inout) :: this
     ! -- local
     integer(I4B) :: i, jaindex, nodenumber
     character(len=100) :: msg
     class(ObserveType), pointer :: obsrv => null()
-! ------------------------------------------------------------------------------
     !
     call this%obs_bd_clear()
     !
@@ -148,72 +135,60 @@ subroutine gwt_obs_bd(this)
       end do
     end if
     !
+    ! -- Return
     return
-  end subroutine gwt_obs_bd
+  end subroutine tsp_obs_bd
 
-  subroutine gwt_obs_rp(this)
-! ******************************************************************************
-! gwt_obs_rp
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    class(GwtObsType), intent(inout) :: this
-! ------------------------------------------------------------------------------
+  !> @brief If transport model observations need checks, add them here
+  !<
+  subroutine tsp_obs_rp(this)
+    ! -- dummy
+    class(TspObsType), intent(inout) :: this
     !
     ! Do GWT observations need any checking? If so, add checks here
+    !
+    ! -- Return
     return
-  end subroutine gwt_obs_rp
+  end subroutine tsp_obs_rp
 
-  subroutine gwt_obs_da(this)
-! ******************************************************************************
-! gwt_obs_da
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> Deallocate memory
+  !!
+  !! Deallocate memory associated with transport model
+  subroutine tsp_obs_da(this)
     ! -- dummy
-    class(GwtObsType), intent(inout) :: this
-! ------------------------------------------------------------------------------
+    class(TspObsType), intent(inout) :: this
     !
     nullify (this%ic)
     nullify (this%x)
     nullify (this%flowja)
     call this%ObsType%obs_da()
     !
+    ! -- Return
     return
-  end subroutine gwt_obs_da
+  end subroutine tsp_obs_da
 
+  !> @brief Set pointers needed by the transport OBS package
+  !<
   subroutine set_pointers(this, ic, x, flowja)
-! ******************************************************************************
-! set_pointers
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
-    class(GwtObsType), intent(inout) :: this
-    type(GwtIcType), pointer, intent(in) :: ic
+    class(TspObsType), intent(inout) :: this
+    type(TspIcType), pointer, intent(in) :: ic
     real(DP), dimension(:), pointer, contiguous, intent(in) :: x
     real(DP), dimension(:), pointer, contiguous, intent(in) :: flowja
-! ------------------------------------------------------------------------------
     !
     this%ic => ic
     this%x => x
     this%flowja => flowja
     !
+    ! -- Return
     return
   end subroutine set_pointers
 
-  ! -- Procedures related to GWF observations (NOT type-bound)
-
+  !> @brief Procedure related to Tsp observations (NOT type-bound)
+  !!
+  !! Process a specific observation ID
+  !<
   subroutine gwt_process_concentration_obs_id(obsrv, dis, inunitobs, iout)
-! ******************************************************************************
-! gwt_process_concentration_obs_id
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(ObserveType), intent(inout) :: obsrv
     class(DisBaseType), intent(in) :: dis
@@ -223,7 +198,6 @@ subroutine gwt_process_concentration_obs_id(obsrv, dis, inunitobs, iout)
     integer(I4B) :: nn1
     integer(I4B) :: icol, istart, istop
     character(len=LINELENGTH) :: ermsg, strng
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize variables
     strng = obsrv%IDstring
@@ -242,16 +216,15 @@ subroutine gwt_process_concentration_obs_id(obsrv, dis, inunitobs, iout)
       call store_error_unit(inunitobs)
     end if
     !
+    ! -- Return
     return
   end subroutine gwt_process_concentration_obs_id
 
-  subroutine gwt_process_intercell_obs_id(obsrv, dis, inunitobs, iout)
-! ******************************************************************************
-! gwt_process_intercell_obs_id
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Procedure related to Tsp observations (NOT type-bound)
+  !!
+  !! Process an intercell observation requested by the user
+  !<
+  subroutine tsp_process_intercell_obs_id(obsrv, dis, inunitobs, iout)
     ! -- dummy
     type(ObserveType), intent(inout) :: obsrv
     class(DisBaseType), intent(in) :: dis
@@ -263,7 +236,6 @@ subroutine gwt_process_intercell_obs_id(obsrv, dis, inunitobs, iout)
     character(len=LINELENGTH) :: ermsg, strng
     ! formats
 70  format('Error: No connection exists between cells identified in text: ', a)
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize variables
     strng = obsrv%IDstring
@@ -304,7 +276,8 @@ subroutine gwt_process_intercell_obs_id(obsrv, dis, inunitobs, iout)
       call store_error_unit(inunitobs)
     end if
     !
+    ! -- Return
     return
-  end subroutine gwt_process_intercell_obs_id
+  end subroutine tsp_process_intercell_obs_id
 
-end module GwtObsModule
+end module TspObsModule
diff --git a/src/Model/GroundWaterTransport/gwt1oc1.f90 b/src/Model/TransportModel/tsp1oc1.f90
similarity index 68%
rename from src/Model/GroundWaterTransport/gwt1oc1.f90
rename to src/Model/TransportModel/tsp1oc1.f90
index d186d713259..cdad8682249 100644
--- a/src/Model/GroundWaterTransport/gwt1oc1.f90
+++ b/src/Model/TransportModel/tsp1oc1.f90
@@ -1,4 +1,4 @@
-module GwtOcModule
+module TspOcModule
 
   use BaseDisModule, only: DisBaseType
   use KindModule, only: DP, I4B
@@ -8,29 +8,28 @@ module GwtOcModule
 
   implicit none
   private
-  public GwtOcType, oc_cr
+  public TspOcType, oc_cr
 
-  !> @ brief Output control for GWT
+  !> @ brief Output control
   !!
-  !!  Concrete implementation of OutputControlType for the
-  !!  GWT Model
+  !!  Concrete implementation of OutputControlType for a
+  !!  Transport Model
   !<
-  type, extends(OutputControlType) :: GwtOcType
+  type, extends(OutputControlType) :: TspOcType
   contains
     procedure :: oc_ar
-  end type GwtOcType
+  end type TspOcType
 
 contains
 
-  !> @ brief Create GwtOcType
+  !> @ brief Create TspOcType
   !!
-  !!  Create by allocating a new GwtOcType object and initializing
+  !!  Create by allocating a new TspOcType object and initializing
   !!  member variables.
-  !!
   !<
   subroutine oc_cr(ocobj, name_model, inunit, iout)
     ! -- dummy
-    type(GwtOcType), pointer :: ocobj !< GwtOcType object
+    type(TspOcType), pointer :: ocobj !< TspOcType object
     character(len=*), intent(in) :: name_model !< name of the model
     integer(I4B), intent(in) :: inunit !< unit number for input
     integer(I4B), intent(in) :: iout !< unit number for output
@@ -52,15 +51,17 @@ subroutine oc_cr(ocobj, name_model, inunit, iout)
     return
   end subroutine oc_cr
 
-  !> @ brief Allocate and read GwtOcType
+  !> @ brief Allocate and read TspOcType
   !!
-  !!  Setup concentration and budget as output control variables.
+  !!  Setup dependent variable (e.g., concentration or temperature)
+  !!  and budget as output control variables.
   !!
   !<
-  subroutine oc_ar(this, conc, dis, dnodata)
+  subroutine oc_ar(this, depvar, dis, dnodata, dvname)
     ! -- dummy
-    class(GwtOcType) :: this !< GwtOcType object
-    real(DP), dimension(:), pointer, contiguous, intent(in) :: conc !< model concentration
+    class(TspOcType) :: this !< TspOcType object
+    real(DP), dimension(:), pointer, contiguous, intent(in) :: depvar !< model concentration
+    character(len=*), intent(in) :: dvname !< name of dependent variable solved by generalized transport model (concentration, temperature)
     class(DisBaseType), pointer, intent(in) :: dis !< model discretization package
     real(DP), intent(in) :: dnodata !< no data value
     ! -- local
@@ -80,7 +81,7 @@ subroutine oc_ar(this, conc, dis, dnodata)
                                 'COLUMNS 10 WIDTH 11 DIGITS 4 GENERAL ', &
                                 this%iout, dnodata)
       case (2)
-        call ocdobjptr%init_dbl('CONCENTRATION', conc, dis, 'PRINT LAST ', &
+        call ocdobjptr%init_dbl(trim(dvname), depvar, dis, 'PRINT LAST ', &
                                 'COLUMNS 10 WIDTH 11 DIGITS 4 GENERAL ', &
                                 this%iout, dnodata)
       end select
@@ -97,4 +98,4 @@ subroutine oc_ar(this, conc, dis, dnodata)
     return
   end subroutine oc_ar
 
-end module GwtOcModule
+end module TspOcModule
diff --git a/src/Model/GroundWaterTransport/gwt1ssm1.f90 b/src/Model/TransportModel/tsp1ssm1.f90
similarity index 92%
rename from src/Model/GroundWaterTransport/gwt1ssm1.f90
rename to src/Model/TransportModel/tsp1ssm1.f90
index e8684820918..ef1e806da4d 100644
--- a/src/Model/GroundWaterTransport/gwt1ssm1.f90
+++ b/src/Model/TransportModel/tsp1ssm1.f90
@@ -1,27 +1,27 @@
-!> @brief This module contains the GwtSsm Module
+!> @brief This module contains the TspSsm Module
 !!
 !! This module contains the code for handling sources and sinks
 !! associated with groundwater flow model stress packages.
 !!
 !! todo: need observations for SSM terms
 !<
-module GwtSsmModule
+module TspSsmModule
 
   use KindModule, only: DP, I4B, LGP
   use ConstantsModule, only: DONE, DZERO, LENAUXNAME, LENFTYPE, &
                              LENPACKAGENAME, LINELENGTH, &
-                             TABLEFT, TABCENTER, LENBUDROWLABEL
+                             TABLEFT, TABCENTER, LENBUDROWLABEL, LENVARNAME
   use SimModule, only: store_error, count_errors, store_error_unit
   use SimVariablesModule, only: errmsg
   use NumericalPackageModule, only: NumericalPackageType
   use BaseDisModule, only: DisBaseType
-  use GwtFmiModule, only: GwtFmiType
+  use TspFmiModule, only: TspFmiType
   use TableModule, only: TableType, table_cr
   use GwtSpcModule, only: GwtSpcType
   use MatrixBaseModule
 
   implicit none
-  public :: GwtSsmType
+  public :: TspSsmType
   public :: ssm_cr
 
   character(len=LENFTYPE) :: ftype = 'SSM'
@@ -32,18 +32,19 @@ module GwtSsmModule
   !! This derived type corresponds to the SSM Package, which adds
   !! the effects of groundwater sources and sinks to the solute transport
   !! equation.
-  !!
   !<
-  type, extends(NumericalPackageType) :: GwtSsmType
+  type, extends(NumericalPackageType) :: TspSsmType
 
     integer(I4B), pointer :: nbound !< total number of flow boundaries in this time step
     integer(I4B), dimension(:), pointer, contiguous :: isrctype => null() !< source type 0 is unspecified, 1 is aux, 2 is auxmixed, 3 is ssmi, 4 is ssmimixed
     integer(I4B), dimension(:), pointer, contiguous :: iauxpak => null() !< aux col for concentration
     integer(I4B), dimension(:), pointer, contiguous :: ibound => null() !< pointer to model ibound
     real(DP), dimension(:), pointer, contiguous :: cnew => null() !< pointer to gwt%x
-    type(GwtFmiType), pointer :: fmi => null() !< pointer to fmi object
+    type(TspFmiType), pointer :: fmi => null() !< pointer to fmi object
     type(TableType), pointer :: outputtab => null() !< output table object
     type(GwtSpcType), dimension(:), pointer :: ssmivec => null() !< array of stress package concentration objects
+    real(DP), pointer :: eqnsclfac => null() !< governing equation scale factor; =1. for solute; =rhow*cpw for energy
+    character(len=LENVARNAME) :: depvartype = ''
 
   contains
 
@@ -68,7 +69,7 @@ module GwtSsmModule
     procedure, private :: set_ssmivec
     procedure, private :: get_ssm_conc
 
-  end type GwtSsmType
+  end type TspSsmType
 
 contains
 
@@ -76,15 +77,17 @@ module GwtSsmModule
   !!
   !!  Create a new SSM package by defining names, allocating scalars
   !!  and initializing the parser.
-  !!
   !<
-  subroutine ssm_cr(ssmobj, name_model, inunit, iout, fmi)
+  subroutine ssm_cr(ssmobj, name_model, inunit, iout, fmi, eqnsclfac, &
+                    depvartype)
     ! -- dummy
-    type(GwtSsmType), pointer :: ssmobj !< GwtSsmType object
+    type(TspSsmType), pointer :: ssmobj !< TspSsmType object
     character(len=*), intent(in) :: name_model !< name of the model
     integer(I4B), intent(in) :: inunit !< fortran unit for input
     integer(I4B), intent(in) :: iout !< fortran unit for output
-    type(GwtFmiType), intent(in), target :: fmi !< GWT FMI package
+    type(TspFmiType), intent(in), target :: fmi !< Transport FMI package
+    real(DP), intent(in), pointer :: eqnsclfac !< governing equation scale factor
+    character(len=LENVARNAME), intent(in) :: depvartype
     !
     ! -- Create the object
     allocate (ssmobj)
@@ -99,10 +102,15 @@ subroutine ssm_cr(ssmobj, name_model, inunit, iout, fmi)
     ssmobj%inunit = inunit
     ssmobj%iout = iout
     ssmobj%fmi => fmi
+    ssmobj%eqnsclfac => eqnsclfac
     !
     ! -- Initialize block parser
     call ssmobj%parser%Initialize(ssmobj%inunit, ssmobj%iout)
     !
+    ! -- Store pointer to labels associated with the current model so that the
+    !    package has access to the corresponding dependent variable type
+    ssmobj%depvartype = depvartype
+    !
     ! -- Return
     return
   end subroutine ssm_cr
@@ -112,13 +120,12 @@ end subroutine ssm_cr
   !! This routine is called from gwt_df(), but does not do anything because
   !! df is typically used to set up dimensions.  For the ssm package, the
   !! total number of ssm entries is defined by the flow model.
-  !!
   !<
   subroutine ssm_df(this)
     ! -- modules
     use MemoryManagerModule, only: mem_setptr
     ! -- dummy
-    class(GwtSsmType) :: this !< GwtSsmType object
+    class(TspSsmType) :: this !< TspSsmType object
     ! -- local
     ! -- formats
     !
@@ -130,13 +137,12 @@ end subroutine ssm_df
   !!
   !! This routine is called from gwt_ar().  It allocates arrays, reads
   !! options and data, and sets up the output table.
-  !!
   !<
   subroutine ssm_ar(this, dis, ibound, cnew)
     ! -- modules
     use MemoryManagerModule, only: mem_setptr
     ! -- dummy
-    class(GwtSsmType) :: this !< GwtSsmType object
+    class(TspSsmType) :: this !< TspSsmType object
     class(DisBaseType), pointer, intent(in) :: dis !< discretization package
     integer(I4B), dimension(:), pointer, contiguous :: ibound !< GWT model ibound
     real(DP), dimension(:), pointer, contiguous :: cnew !< GWT model dependent variable
@@ -188,12 +194,11 @@ end subroutine ssm_ar
   !! each stress period.  If any SPC input files are used to provide source
   !! and sink concentrations, then period blocks for the current stress period
   !! are read.
-  !!
   !<
   subroutine ssm_rp(this)
     ! -- modules
     ! -- dummy
-    class(GwtSsmType) :: this !< GwtSsmType object
+    class(TspSsmType) :: this !< TspSsmType object
     ! -- local
     integer(I4B) :: ip
     type(GwtSpcType), pointer :: ssmiptr
@@ -219,12 +224,11 @@ end subroutine ssm_rp
   !! in this%nbound.  Also, if any SPC input files are used to provide source
   !! and sink concentrations and time series are referenced in those files,
   !! then ssm concenrations must be interpolated for the time step.
-  !!
   !<
   subroutine ssm_ad(this)
     ! -- modules
     ! -- dummy
-    class(GwtSsmType) :: this !< GwtSsmType object
+    class(TspSsmType) :: this !< TspSsmType object
     ! -- local
     integer(I4B) :: ip
     type(GwtSpcType), pointer :: ssmiptr
@@ -267,12 +271,11 @@ end subroutine ssm_ad
   !! and right-hand-side value for any package and package entry.  It returns
   !! several different optional variables that are used throughout this
   !! package to update matrix terms, budget calculations, and output tables.
-  !!
   !<
   subroutine ssm_term(this, ipackage, ientry, rrate, rhsval, hcofval, &
                       cssm, qssm)
     ! -- dummy
-    class(GwtSsmType) :: this !< GwtSsmType
+    class(TspSsmType) :: this !< TspSsmType
     integer(I4B), intent(in) :: ipackage !< package number
     integer(I4B), intent(in) :: ientry !< bound number
     real(DP), intent(out), optional :: rrate !< calculated mass flow rate
@@ -342,9 +345,9 @@ subroutine ssm_term(this, ipackage, ientry, rrate, rhsval, hcofval, &
       !
       ! -- Add terms based on qbnd sign
       if (qbnd <= DZERO) then
-        hcoftmp = qbnd * omega
+        hcoftmp = qbnd * omega * this%eqnsclfac
       else
-        rhstmp = -qbnd * ctmp * (DONE - omega)
+        rhstmp = -qbnd * ctmp * (DONE - omega) * this%eqnsclfac
       end if
       !
       ! -- end of active ibound
@@ -357,23 +360,23 @@ subroutine ssm_term(this, ipackage, ientry, rrate, rhsval, hcofval, &
     if (present(cssm)) cssm = ctmp
     if (present(qssm)) qssm = qbnd
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine ssm_term
 
-  !> @ brief Provide bound concentration and mixed flag
-  !!
-  !! SSM concentrations can be provided in auxiliary variables or
-  !! through separate SPC files.  If not provided, the default
-  !! concentration is zero.  This single routine provides the SSM
-  !! bound concentration based on these different approaches.
-  !! The mixed flag indicates whether or not
+  !> @ brief Provide bound concentration (or temperature) and mixed flag
   !!
+  !! SSM concentrations and temperatures can be provided in auxiliary variables
+  !! or through separate SPC files.  If not provided, the default
+  !! concentration (or temperature) is zero.  This single routine provides
+  !! the SSM bound concentration (or temperature) based on these different
+  !! approaches. The mixed flag indicates whether or not the boundary as a
+  !! mixed type.
   !<
   subroutine get_ssm_conc(this, ipackage, ientry, nbound_flow, conc, &
                           lauxmixed)
     ! -- dummy
-    class(GwtSsmType) :: this !< GwtSsmType
+    class(TspSsmType) :: this !< TspSsmType
     integer(I4B), intent(in) :: ipackage !< package number
     integer(I4B), intent(in) :: ientry !< bound number
     integer(I4B), intent(in) :: nbound_flow !< size of flow package bound list
@@ -396,7 +399,8 @@ subroutine get_ssm_conc(this, ipackage, ientry, nbound_flow, conc, &
       conc = this%ssmivec(ipackage)%get_value(ientry, nbound_flow)
       if (isrctype == 4) lauxmixed = .true.
     end select
-
+    !
+    ! -- Return
     return
   end subroutine get_ssm_conc
 
@@ -404,12 +408,11 @@ end subroutine get_ssm_conc
   !!
   !! This routine adds the effects of the SSM to the matrix equations by
   !! updating the a matrix and right-hand side vector.
-  !!
   !<
   subroutine ssm_fc(this, matrix_sln, idxglo, rhs)
     ! -- modules
     ! -- dummy
-    class(GwtSsmType) :: this
+    class(TspSsmType) :: this
     class(MatrixBaseType), pointer :: matrix_sln
     integer(I4B), intent(in), dimension(:) :: idxglo
     real(DP), intent(inout), dimension(:) :: rhs
@@ -451,12 +454,11 @@ end subroutine ssm_fc
   !! Calulate the resulting mass flow between the boundary and the connected
   !! GWT model cell.  Update the diagonal position of the flowja array so that
   !! it ultimately contains the solute balance residual.
-  !!
   !<
   subroutine ssm_cq(this, flowja)
     ! -- modules
     ! -- dummy
-    class(GwtSsmType) :: this !< GwtSsmType object
+    class(TspSsmType) :: this !< TspSsmType object
     real(DP), dimension(:), contiguous, intent(inout) :: flowja !< flow across each face in the model grid
     ! -- local
     integer(I4B) :: ip
@@ -491,14 +493,13 @@ end subroutine ssm_cq
   !!
   !! Calculate the global SSM budget terms using separate in and out entries
   !! for each flow package.
-  !!
   !<
   subroutine ssm_bd(this, isuppress_output, model_budget)
     ! -- modules
     use TdisModule, only: delt
     use BudgetModule, only: BudgetType
     ! -- dummy
-    class(GwtSsmType) :: this !< GwtSsmType object
+    class(TspSsmType) :: this !< TspSsmType object
     integer(I4B), intent(in) :: isuppress_output !< flag to suppress output
     type(BudgetType), intent(inout) :: model_budget !< budget object for the GWT model
     ! -- local
@@ -549,14 +550,13 @@ end subroutine ssm_bd
   !! Based on user-specified controls, print SSM mass flow rates to the GWT
   !! listing file and/or write the SSM mass flow rates to the GWT binary
   !! budget file.
-  !!
   !<
   subroutine ssm_ot_flow(this, icbcfl, ibudfl, icbcun)
     ! -- modules
     use TdisModule, only: kstp, kper
     use ConstantsModule, only: LENPACKAGENAME, LENBOUNDNAME, LENAUXNAME, DZERO
     ! -- dummy
-    class(GwtSsmType) :: this !< GwtSsmType object
+    class(TspSsmType) :: this !< TspSsmType object
     integer(I4B), intent(in) :: icbcfl !< flag for writing binary budget terms
     integer(I4B), intent(in) :: ibudfl !< flag for printing budget terms to list file
     integer(I4B), intent(in) :: icbcun !< fortran unit number for binary budget file
@@ -672,20 +672,19 @@ subroutine ssm_ot_flow(this, icbcfl, ibudfl, icbcun)
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine ssm_ot_flow
 
   !> @ brief Deallocate
   !!
   !! Deallocate the memory associated with this derived type
-  !!
   !<
   subroutine ssm_da(this)
     ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     ! -- dummy
-    class(GwtSsmType) :: this !< GwtSsmType object
+    class(TspSsmType) :: this !< TspSsmType object
     ! -- local
     integer(I4B) :: ip
     type(GwtSpcType), pointer :: ssmiptr
@@ -729,13 +728,12 @@ end subroutine ssm_da
   !> @ brief Allocate scalars
   !!
   !! Allocate scalar variables for this derived type
-  !!
   !<
   subroutine allocate_scalars(this)
     ! -- modules
     use MemoryManagerModule, only: mem_allocate, mem_setptr
     ! -- dummy
-    class(GwtSsmType) :: this !< GwtSsmType object
+    class(TspSsmType) :: this !< TspSsmType object
     ! -- local
     !
     ! -- allocate scalars in NumericalPackageType
@@ -754,13 +752,12 @@ end subroutine allocate_scalars
   !> @ brief Allocate arrays
   !!
   !! Allocate array variables for this derived type
-  !!
   !<
   subroutine allocate_arrays(this)
     ! -- modules
     use MemoryManagerModule, only: mem_allocate, mem_setptr
     ! -- dummy
-    class(GwtSsmType) :: this !< GwtSsmType object
+    class(TspSsmType) :: this !< TspSsmType object
     ! -- local
     integer(I4B) :: nflowpack
     integer(I4B) :: i
@@ -786,12 +783,11 @@ end subroutine allocate_arrays
   !> @ brief Read package options
   !!
   !! Read and set the SSM Package options
-  !!
   !<
   subroutine read_options(this)
     ! -- modules
     ! -- dummy
-    class(GwtSSMType) :: this !< GwtSsmType object
+    class(TspSsmType) :: this !< TspSsmType object
     ! -- local
     character(len=LINELENGTH) :: keyword
     integer(I4B) :: ierr
@@ -838,17 +834,18 @@ end subroutine read_options
   !> @ brief Read package data
   !!
   !! Read and set the SSM Package data
-  !!
   !<
   subroutine read_data(this)
     ! -- dummy
-    class(GwtSsmtype) :: this !< GwtSsmtype object
+    class(TspSsmType) :: this !< TspSsmType object
     !
     ! -- read and process required SOURCES block
     call this%read_sources_aux()
     !
     ! -- read and process optional FILEINPUT block
     call this%read_sources_fileinput()
+    !
+    ! -- Return
     return
   end subroutine read_data
 
@@ -856,11 +853,10 @@ end subroutine read_data
   !!
   !! Read SOURCES block and look for auxiliary columns in
   !! corresponding flow data.
-  !!
   !<
   subroutine read_sources_aux(this)
     ! -- dummy
-    class(GwtSsmtype) :: this !< GwtSsmtype object
+    class(TspSsmType) :: this !< TspSsmType object
     ! -- local
     character(len=LINELENGTH) :: keyword
     character(len=20) :: srctype
@@ -959,11 +955,10 @@ end subroutine read_sources_aux
   !!
   !! Read optional FILEINPUT block and initialize an
   !! SPC input file reader for each entry.
-  !!
   !<
   subroutine read_sources_fileinput(this)
     ! -- dummy
-    class(GwtSsmtype) :: this !< GwtSsmtype object
+    class(TspSsmType) :: this !< TspSsmType object
     ! -- local
     character(len=LINELENGTH) :: keyword
     character(len=LINELENGTH) :: keyword2
@@ -1080,11 +1075,10 @@ end subroutine read_sources_fileinput
   !!  through the auxiliary names in package ip and sets iauxpak
   !!  to the column number corresponding to the correct auxiliary
   !!  column.
-  !!
   !<
   subroutine set_iauxpak(this, ip, packname)
     ! -- dummy
-    class(GwtSsmtype), intent(inout) :: this !< GwtSsmtype
+    class(TspSsmType), intent(inout) :: this !< TspSsmType
     integer(I4B), intent(in) :: ip !< package number
     character(len=*), intent(in) :: packname !< name of package
     ! -- local
@@ -1114,7 +1108,7 @@ subroutine set_iauxpak(this, ip, packname)
     write (this%iout, '(4x, a, i0, a, a)') 'USING AUX COLUMN ', &
       iaux, ' IN PACKAGE ', trim(packname)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine set_iauxpak
 
@@ -1123,13 +1117,12 @@ end subroutine set_iauxpak
   !!  The next call to parser will return the input file name for
   !!  package ip in the SSM SOURCES block.  The routine then
   !!  initializes the SPC input file.
-  !!
   !<
   subroutine set_ssmivec(this, ip, packname)
     ! -- module
     use InputOutputModule, only: openfile, getunit
     ! -- dummy
-    class(GwtSsmtype), intent(inout) :: this !< GwtSsmtype
+    class(TspSsmType), intent(inout) :: this !< TspSsmType
     integer(I4B), intent(in) :: ip !< package number
     character(len=*), intent(in) :: packname !< name of package
     ! -- local
@@ -1147,21 +1140,21 @@ subroutine set_ssmivec(this, ip, packname)
     call ssmiptr%initialize(this%dis, ip, inunit, this%iout, this%name_model, &
                             trim(packname))
 
-    write (this%iout, '(4x, a, a, a, a)') 'USING SPC INPUT FILE ', &
-      trim(filename), ' TO SET CONCENTRATIONS FOR PACKAGE ', trim(packname)
+    write (this%iout, '(4x, a, a, a, a, a)') 'USING SPC INPUT FILE ', &
+      trim(filename), ' TO SET ', trim(this%depvartype), &
+      'S FOR PACKAGE ', trim(packname)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine set_ssmivec
 
   !> @ brief Setup the output table
   !!
   !! Setup the output table by creating the column headers.
-  !!
   !<
   subroutine pak_setup_outputtab(this)
     ! -- dummy
-    class(GwtSsmtype), intent(inout) :: this
+    class(TspSsmType), intent(inout) :: this
     ! -- local
     character(len=LINELENGTH) :: title
     character(len=LINELENGTH) :: text
@@ -1199,8 +1192,8 @@ subroutine pak_setup_outputtab(this)
       !end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine pak_setup_outputtab
 
-end module GwtSsmModule
+end module TspSsmModule
diff --git a/src/RunControl.f90 b/src/RunControl.f90
index fd1b9b0611b..6872f119da0 100644
--- a/src/RunControl.f90
+++ b/src/RunControl.f90
@@ -22,6 +22,7 @@ module RunControlModule
     procedure :: finish => ctrl_finish
     ! private
     procedure, private :: init_handler
+    procedure, private :: after_con_cr_handler
     procedure, private :: before_con_df_handler
     procedure, private :: after_con_df_handler
     procedure, private :: destroy
@@ -69,6 +70,8 @@ subroutine ctrl_at_stage(this, stage)
 
     if (stage == STG_BFR_MDL_DF) then
       call this%init_handler()
+    else if (stage == STG_AFT_CON_CR) then
+      call this%after_con_cr_handler()
     else if (stage == STG_BFR_CON_DF) then
       call this%before_con_df_handler()
     else if (stage == STG_AFT_CON_DF) then
@@ -90,6 +93,15 @@ subroutine init_handler(this)
 
   end subroutine init_handler
 
+  !> @brief Actions after connections have been created
+  !<
+  subroutine after_con_cr_handler(this)
+    class(RunControlType), target :: this
+
+    call this%virtual_data_mgr%set_halo()
+
+  end subroutine after_con_cr_handler
+
   !> @brief Actions before defining the connections
   !!
   !! Set up the virtual data manager:
diff --git a/src/SimulationCreate.f90 b/src/SimulationCreate.f90
index 6407097b7b2..ce5c0fc1a19 100644
--- a/src/SimulationCreate.f90
+++ b/src/SimulationCreate.f90
@@ -8,7 +8,6 @@ module SimulationCreateModule
   use SimVariablesModule, only: iout, simulation_mode, proc_id, &
                                 nr_procs, model_names, model_ranks, &
                                 model_loc_idx
-  use GenericUtilitiesModule, only: sim_message, write_centered
   use SimModule, only: store_error, count_errors, &
                        store_error_filename, MaxErrors
   use VersionModule, only: write_listfile_header
@@ -341,11 +340,14 @@ subroutine exchanges_create()
       pointer :: emnames_a !< model a names
     type(CharacterStringType), dimension(:), contiguous, &
       pointer :: emnames_b !< model b names
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: emempaths
     character(len=LINELENGTH) :: exgtype
     integer(I4B) :: exg_id
     integer(I4B) :: m1_id, m2_id
     character(len=LINELENGTH) :: fname, name1, name2
     character(len=LENEXCHANGENAME) :: exg_name
+    character(len=LENMEMPATH) :: exg_mempath
     integer(I4B) :: n
     character(len=LINELENGTH) :: errmsg
     logical(LGP) :: terminate = .true.
@@ -362,6 +364,7 @@ subroutine exchanges_create()
     call mem_setptr(efiles, 'EXGFILE', input_mempath)
     call mem_setptr(emnames_a, 'EXGMNAMEA', input_mempath)
     call mem_setptr(emnames_b, 'EXGMNAMEB', input_mempath)
+    call mem_setptr(emempaths, 'EXGMEMPATHS', input_mempath)
     !
     ! -- open exchange logging block
     write (iout, '(/1x,a)') 'READING SIMULATION EXCHANGES'
@@ -377,6 +380,7 @@ subroutine exchanges_create()
       fname = efiles(n)
       name1 = emnames_a(n)
       name2 = emnames_b(n)
+      exg_mempath = emempaths(n)
 
       exg_id = exg_id + 1
 
@@ -407,7 +411,8 @@ subroutine exchanges_create()
       case ('GWF6-GWF6')
         write (exg_name, '(a,i0)') 'GWF-GWF_', exg_id
         if (.not. both_remote) then
-          call gwfexchange_create(fname, exg_name, exg_id, m1_id, m2_id)
+          call gwfexchange_create(fname, exg_name, exg_id, m1_id, m2_id, &
+                                  exg_mempath)
         end if
         call add_virtual_gwf_exchange(exg_name, exg_id, m1_id, m2_id)
       case ('GWF6-GWT6')
@@ -417,7 +422,8 @@ subroutine exchanges_create()
       case ('GWT6-GWT6')
         write (exg_name, '(a,i0)') 'GWT-GWT_', exg_id
         if (.not. both_remote) then
-          call gwtexchange_create(fname, exg_name, exg_id, m1_id, m2_id)
+          call gwtexchange_create(fname, exg_name, exg_id, m1_id, m2_id, &
+                                  exg_mempath)
         end if
         call add_virtual_gwt_exchange(exg_name, exg_id, m1_id, m2_id)
       case default
@@ -521,7 +527,7 @@ subroutine solution_groups_create()
     call mem_setptr(slntype, 'SLNTYPE', input_mempath)
     call mem_setptr(slnfname, 'SLNFNAME', input_mempath)
     call mem_setptr(slnmnames, 'SLNMNAMES', input_mempath)
-    call mem_setptr(blocknum, 'SOLUTIONGROUPnum', input_mempath)
+    call mem_setptr(blocknum, 'SOLUTIONGROUPNUM', input_mempath)
     !
     ! -- open solution group logging block
     write (iout, '(/1x,a)') 'READING SOLUTIONGROUP'
diff --git a/src/Solution/ConvergenceSummary.f90 b/src/Solution/ConvergenceSummary.f90
new file mode 100644
index 00000000000..5e85ccc7aaf
--- /dev/null
+++ b/src/Solution/ConvergenceSummary.f90
@@ -0,0 +1,138 @@
+module ConvergenceSummaryModule
+  use KindModule, only: I4B, DP
+  use ConstantsModule, only: LENMEMPATH, DZERO
+  use MemoryManagerModule, only: mem_allocate, mem_deallocate, mem_reallocate
+
+  implicit none
+  private
+
+  public :: ConvergenceSummaryType
+
+  !> This structure stores the generic convergence info for a solution
+  !<
+  type :: ConvergenceSummaryType
+    character(len=LENMEMPATH) :: memory_path !< the path for storing solution variables in the memory manager
+    integer(I4B) :: iter_cnt !< tracks the iteration number within the timestep
+    integer(I4B), pointer :: convnmod => null() !< number of models in the solution
+    integer(I4B), dimension(:), pointer :: model_bounds => null() !< the start and stop index of the models in the solution
+    integer(I4B), pointer :: nitermax => null() !< max. nr. of iterations in a timestep
+    integer(I4B), dimension(:), pointer, contiguous :: itinner => null() !< inner iteration number within each picard iteration
+    integer(I4B), dimension(:), pointer, contiguous :: locdv => null() !< location of the maximum dependent-variable change in the solution
+    real(DP), dimension(:), pointer, contiguous :: dvmax => null() !< maximum dependent-variable change in the solution
+    integer(I4B), dimension(:), pointer, contiguous :: locdr => null() !< location of the maximum flow change in the solution
+    real(DP), dimension(:), pointer, contiguous :: drmax => null() !< maximum flow change in the solution
+    integer(I4B), pointer, dimension(:, :), contiguous :: convlocdv => null() !< location of the maximum dependent-variable change in each model in the solution
+    real(DP), pointer, dimension(:, :), contiguous :: convdvmax => null() !< maximum dependent-variable change for each model in the solution
+    integer(I4B), pointer, dimension(:, :), contiguous :: convlocdr => null() !< location of the maximum flow change in each model in the solution
+    real(DP), pointer, dimension(:, :), contiguous :: convdrmax => null() !< maximum flow change in each model in the solution
+  contains
+    procedure :: init
+    procedure :: reinit
+    procedure :: destroy
+    ! private
+    procedure, private :: set_defaults
+  end type ConvergenceSummaryType
+
+contains
+
+  !> @brief Initialize the convergence summary for a solution
+  subroutine init(this, nr_models, model_bounds, mem_path)
+    class(ConvergenceSummaryType) :: this
+    integer(I4B) :: nr_models !< the number of models in the solution
+    integer(I4B), dimension(:), pointer :: model_bounds !< the start and stop index of the models
+    character(len=*) :: mem_path !< the memory path of the owning solution
+
+    this%memory_path = 'TMP'//mem_path
+    this%iter_cnt = 0
+    this%model_bounds => model_bounds
+
+    call mem_allocate(this%convnmod, 'CONVNMOD', this%memory_path)
+    call mem_allocate(this%nitermax, 'NITERMAX', this%memory_path)
+    this%convnmod = nr_models
+    this%nitermax = 0
+
+    call mem_allocate(this%itinner, 0, 'ITINNER', this%memory_path)
+    call mem_allocate(this%locdv, this%convnmod, 'LOCDV', this%memory_path)
+    call mem_allocate(this%dvmax, this%convnmod, 'DVMAX', this%memory_path)
+    call mem_allocate(this%locdr, this%convnmod, 'LOCDR', this%memory_path)
+    call mem_allocate(this%drmax, this%convnmod, 'DRMAX', this%memory_path)
+    call mem_allocate(this%convdvmax, this%convnmod, 0, 'CONVDVMAX', &
+                      this%memory_path)
+    call mem_allocate(this%convlocdv, this%convnmod, 0, 'CONVLOCDV', &
+                      this%memory_path)
+    call mem_allocate(this%convdrmax, this%convnmod, 0, 'CONVDRMAX', &
+                      this%memory_path)
+    call mem_allocate(this%convlocdr, this%convnmod, 0, 'CONVLOCDR', &
+                      this%memory_path)
+
+    call this%set_defaults()
+
+  end subroutine init
+
+  subroutine reinit(this, niter_max)
+    class(ConvergenceSummaryType) :: this
+    integer(I4B) :: niter_max !< max. nr. of iterations in a timestep
+
+    this%nitermax = niter_max
+    call mem_reallocate(this%itinner, niter_max, 'ITINNER', this%memory_path)
+    call mem_reallocate(this%convdvmax, this%convnmod, niter_max, 'CONVDVMAX', &
+                        this%memory_path)
+    call mem_reallocate(this%convlocdv, this%convnmod, niter_max, 'CONVLOCDV', &
+                        this%memory_path)
+    call mem_reallocate(this%convdrmax, this%convnmod, niter_max, 'CONVDRMAX', &
+                        this%memory_path)
+    call mem_reallocate(this%convlocdr, this%convnmod, niter_max, 'CONVLOCDR', &
+                        this%memory_path)
+
+    call this%set_defaults()
+
+  end subroutine reinit
+
+  subroutine set_defaults(this)
+    class(ConvergenceSummaryType) :: this
+    ! local
+    integer(I4B) :: i, j
+
+    do i = 1, this%convnmod
+      this%locdr(i) = 0
+      this%dvmax(i) = DZERO
+      this%locdv(i) = 0
+      this%drmax(i) = DZERO
+    end do
+
+    do i = 1, this%nitermax
+      this%itinner(i) = 0
+      do j = 1, this%convnmod
+        this%convdvmax(j, i) = DZERO
+        this%convlocdv(j, i) = 0
+        this%convdrmax(j, i) = DZERO
+        this%convlocdr(j, i) = 0
+      end do
+    end do
+
+  end subroutine set_defaults
+
+  !> @brief Cleanup
+  !<
+  subroutine destroy(this)
+    class(ConvergenceSummaryType) :: this
+
+    ! scalars
+    call mem_deallocate(this%convnmod)
+    call mem_deallocate(this%nitermax)
+
+    call mem_deallocate(this%locdr)
+    call mem_deallocate(this%drmax)
+    call mem_deallocate(this%locdv)
+    call mem_deallocate(this%dvmax)
+
+    ! arrays
+    call mem_deallocate(this%itinner)
+    call mem_deallocate(this%convdvmax)
+    call mem_deallocate(this%convlocdv)
+    call mem_deallocate(this%convdrmax)
+    call mem_deallocate(this%convlocdr)
+
+  end subroutine destroy
+
+end module ConvergenceSummaryModule
diff --git a/src/Solution/ExplicitSolution.f90 b/src/Solution/ExplicitSolution.f90
index 8cd8fb7f24b..d40a2fe4046 100644
--- a/src/Solution/ExplicitSolution.f90
+++ b/src/Solution/ExplicitSolution.f90
@@ -1,11 +1,4 @@
-!> @brief Explicit Solution Module
-!!
-!! This module contains the Explicit Solution, which is a
-!! class for solving explicit models.  The explicit solution
-!! scrolls through a list of explicit models and calls
-!! methods in a prescribed sequence.
-!!
-!<
+!> @brief Explicit model solution
 module ExplicitSolutionModule
   use KindModule, only: I4B, DP
   use TimerModule, only: code_timer
@@ -22,19 +15,20 @@ module ExplicitSolutionModule
   use ListsModule, only: basesolutionlist
   use SimVariablesModule, only: iout, isim_mode
   use BlockParserModule, only: BlockParserType
+  use MemoryManagerModule, only: mem_allocate, mem_deallocate
+  use InputOutputModule, only: getunit
 
   implicit none
   private
 
-  !> @brief Derived type for the Explicit Solution Type
-  !!
-  !! This derived type describes the solution for managing and
-  !! solving explicit models.
-  !!
-  !<
   public :: create_explicit_solution
   public :: ExplicitSolutionType
 
+  !> @brief Manages and solves explicit models.
+  !!
+  !! An explicit solution simply scrolls through a list of explicit
+  !! models and calls solution procedures in a prescribed sequence.
+  !<
   type, extends(BaseSolutionType) :: ExplicitSolutionType
     character(len=LENMEMPATH) :: memoryPath !< the path for storing solution variables in the memory manager
     type(ListType), pointer :: modellist !< list of models in solution
@@ -71,10 +65,9 @@ module ExplicitSolutionModule
 
   !> @ brief Create a new solution
   !!
-  !!  Create a new solution using the data in filename, assign this new
-  !!  solution an id number and store the solution in the basesolutionlist.
-  !!  Also open the filename for later reading.
-  !!
+  !! Create a new solution using the data in filename, assign this new
+  !! solution an id number and store the solution in the basesolutionlist.
+  !! Also open the filename for later reading.
   !<
   subroutine create_explicit_solution(exp_sol, filename, id)
     ! -- modules
@@ -87,101 +80,77 @@ subroutine create_explicit_solution(exp_sol, filename, id)
     integer(I4B) :: inunit
     class(BaseSolutionType), pointer :: solbase => null()
     character(len=LENSOLUTIONNAME) :: solutionname
-    !
+
     ! -- Create a new solution and add it to the basesolutionlist container
     solbase => exp_sol
     write (solutionname, '(a, i0)') 'SLN_', id
-
     exp_sol%name = solutionname
     exp_sol%memoryPath = create_mem_path(solutionname)
     allocate (exp_sol%modellist)
     !todo: do we need this?  allocate (exp_sol%exchangelist)
-    !
     call exp_sol%allocate_scalars()
-    !
     call AddBaseSolutionToList(basesolutionlist, solbase)
-    !
     exp_sol%id = id
-    !
+
     ! -- Open solution input file for reading later after problem size is known
     !    Check to see if the file is already opened, which can happen when
     !    running in single model mode
     inquire (file=filename, number=inunit)
-
     if (inunit < 0) inunit = getunit()
     exp_sol%iu = inunit
     write (iout, '(/a,a/)') ' Creating explicit solution (EMS): ', exp_sol%name
     call openfile(exp_sol%iu, iout, filename, 'IMS')
-    !
+
     ! -- Initialize block parser
     call exp_sol%parser%Initialize(exp_sol%iu, iout)
-    !
-    ! -- return
-    return
   end subroutine create_explicit_solution
 
   !> @ brief Allocate scalars
-  !!
-  !!  Allocate scalars for a new solution.
-  !!
   !<
   subroutine allocate_scalars(this)
-    ! -- modules
-    use MemoryManagerModule, only: mem_allocate
-    ! -- dummy variables
     class(ExplicitSolutionType) :: this !< ExplicitSolutionType instance
-    !
+
     ! -- allocate scalars
     call mem_allocate(this%id, 'ID', this%memoryPath)
     call mem_allocate(this%iu, 'IU', this%memoryPath)
     call mem_allocate(this%ttsoln, 'TTSOLN', this%memoryPath)
     call mem_allocate(this%icnvg, 'ICNVG', this%memoryPath)
-    !
+
     ! -- initialize
     this%id = 0
     this%iu = 0
     this%ttsoln = DZERO
     this%icnvg = 0
-    !
-    ! -- return
-    return
   end subroutine allocate_scalars
 
-  !> @ brief Solution define
+  !> @ brief Define the solution
   !<
   subroutine sln_df(this)
     class(ExplicitSolutionType) :: this
   end subroutine
 
-  !> @ brief Solution allocate and read
+  !> @ brief Allocate and read
   !<
   subroutine sln_ar(this)
-    ! -- dummy variables
     class(ExplicitSolutionType) :: this !< ExplicitSolutionType instance
-    !
+
     ! -- close ems input file
     call this%parser%Clear()
-    !
-    ! -- return
-    return
   end subroutine sln_ar
 
-  !> @ brief Solution calculate time step length
+  !> @ brief Calculate time step length
   !<
   subroutine sln_calculate_delt(this)
     class(ExplicitSolutionType) :: this !< ExplicitSolutionType instance
   end subroutine sln_calculate_delt
 
-  !> @ brief Solution advance
+  !> @ brief Advance the solution
   !<
   subroutine sln_ad(this)
-    ! -- dummy variables
     class(ExplicitSolutionType) :: this !< ExplicitSolutionType instance
-    !
+
     ! -- reset convergence flag
     this%icnvg = 0
-
-    return
   end subroutine sln_ad
 
   !> @ brief Solution output
@@ -194,33 +163,25 @@ subroutine sln_fp(this)
     class(ExplicitSolutionType) :: this !< ExplicitSolutionType instance
   end subroutine sln_fp
 
-  !> @ brief Solution deallocate
+  !> @ brief Deallocate
   !<
   subroutine sln_da(this)
-    ! -- modules
-    use MemoryManagerModule, only: mem_deallocate
-    ! -- dummy variables
     class(ExplicitSolutionType) :: this !< ExplicitSolutionType instance
-    !
+
     ! -- lists
     call this%modellist%Clear()
     deallocate (this%modellist)
-    !
-    !
+
     ! -- Scalars
     call mem_deallocate(this%id)
     call mem_deallocate(this%iu)
     call mem_deallocate(this%ttsoln)
     call mem_deallocate(this%icnvg)
-    !
-    ! -- return
-    return
   end subroutine sln_da
 
-  !> @ brief Solution calculate
+  !> @ brief Calculate
   !<
   subroutine sln_ca(this, isgcnvg, isuppress_output)
-    ! -- modules
     ! -- dummy variables
     class(ExplicitSolutionType) :: this !< ExplicitSolutionType instance
     integer(I4B), intent(inout) :: isgcnvg !< solution group convergence flag
@@ -250,13 +211,9 @@ subroutine sln_ca(this, isgcnvg, isuppress_output)
       ! finish up
       call this%finalizeSolve(isgcnvg, isuppress_output)
     end select
-    !
-    ! -- return
-    return
-
   end subroutine sln_ca
 
-  !> @ brief Solution prepare to solve
+  !> @ brief Prepare to solve
   !<
   subroutine prepareSolve(this)
     ! -- dummy variables
@@ -273,10 +230,9 @@ subroutine prepareSolve(this)
 
     ! advance solution
     call this%sln_ad()
-
   end subroutine prepareSolve
 
-  !> @ brief Solution solve each model
+  !> @ brief Solve each model
   !<
   subroutine solve(this)
     ! -- dummy variables
@@ -285,20 +241,17 @@ subroutine solve(this)
     class(ExplicitModelType), pointer :: mp => null()
     integer(I4B) :: im
     real(DP) :: ttsoln
-    !
-    ! -- particle solve
+
     call code_timer(0, ttsoln, this%ttsoln)
     do im = 1, this%modellist%Count()
       mp => GetExplicitModelFromList(this%modellist, im)
       call mp%model_solve()
     end do
     call code_timer(1, ttsoln, this%ttsoln)
-    !
     this%icnvg = 1
-
   end subroutine solve
 
-  !> @ brief Solution finalize solve
+  !> @ brief Finalize solve
   !<
   subroutine finalizeSolve(this, isgcnvg, isuppress_output)
     ! -- dummy variables
@@ -308,42 +261,36 @@ subroutine finalizeSolve(this, isgcnvg, isuppress_output)
     ! -- local variables
     integer(I4B) :: im
     class(ExplicitModelType), pointer :: mp => null()
-    !
+
     ! -- Calculate flow for each model
     do im = 1, this%modellist%Count()
       mp => GetExplicitModelFromList(this%modellist, im)
       call mp%model_cq(this%icnvg, isuppress_output)
     end do
-    !
+
     ! -- Budget terms for each model
     do im = 1, this%modellist%Count()
       mp => GetExplicitModelFromList(this%modellist, im)
       call mp%model_bd(this%icnvg, isuppress_output)
     end do
-    !
   end subroutine finalizeSolve
 
-  !> @ brief Solution save
+  !> @ brief Save output
   !<
   subroutine save(this, filename)
-    ! -- modules
-    use InputOutputModule, only: getunit
     ! -- dummy variables
     class(ExplicitSolutionType) :: this !< ExplicitSolutionType instance
     character(len=*), intent(in) :: filename !< filename to save solution data
     ! -- local variables
     integer(I4B) :: inunit
-    !
+
     inunit = getunit()
     open (unit=inunit, file=filename, status='unknown')
     write (inunit, *) 'The save routine currently writes nothing'
     close (inunit)
-    !
-    ! -- return
-    return
   end subroutine save
 
-  !> @ brief Solution explicit model to list
+  !> @ brief Add explicit model to list
   !<
   subroutine add_model(this, mp)
     ! -- dummy variables
@@ -351,41 +298,32 @@ subroutine add_model(this, mp)
     class(BaseModelType), pointer, intent(in) :: mp !< model instance
     ! -- local variables
     class(ExplicitModelType), pointer :: m => null()
-    !
+
     ! -- add a model
     select type (mp)
     class is (ExplicitModelType)
       m => mp
       call AddExplicitModelToList(this%modellist, m)
     end select
-    !
-    ! -- return
-    return
   end subroutine add_model
 
-  !> @brief Get a list of models
-  !!
-  !!  Returns a pointer to the list of models in this solution.
-  !!
+  !> @brief Get a pointer to a list of models in the solution
   !<
   function get_models(this) result(models)
-    ! -- return variable
     type(ListType), pointer :: models !< pointer to the model list
-    ! -- dummy variables
     class(ExplicitSolutionType) :: this !< ExplicitSolutionType instance
 
     models => this%modellist
-
   end function get_models
 
-  !> @ brief Solution add exchange to list of exchanges
+  !> @ brief Add exchange to list of exchanges
   !<
   subroutine add_exchange(this, exchange)
     class(ExplicitSolutionType) :: this
     class(BaseExchangeType), pointer, intent(in) :: exchange
   end subroutine add_exchange
 
-  !> @ brief Solution get list of exchanges
+  !> @ brief Get list of exchanges
   !<
   function get_exchanges(this) result(exchanges)
     class(ExplicitSolutionType) :: this
diff --git a/src/Solution/LinearMethods/ImsLinearSettings.f90 b/src/Solution/LinearMethods/ImsLinearSettings.f90
new file mode 100644
index 00000000000..675076ab941
--- /dev/null
+++ b/src/Solution/LinearMethods/ImsLinearSettings.f90
@@ -0,0 +1,273 @@
+module ImsLinearSettingsModule
+  use KindModule
+  use ConstantsModule
+  use MemoryManagerModule, only: mem_allocate, mem_deallocate
+  use BlockParserModule, only: BlockParserType
+  use SimModule, only: store_error, deprecation_warning
+  implicit none
+  private
+
+  integer(I4B), public, parameter :: CG_METHOD = 1
+  integer(I4B), public, parameter :: BCGS_METHOD = 2
+
+  type, public :: ImsLinearSettingsType
+    character(len=LENMEMPATH) :: memory_path
+    real(DP), pointer :: dvclose => null() !< dependent variable closure criterion
+    real(DP), pointer :: rclose => null() !< residual closure criterion
+    integer(I4B), pointer :: icnvgopt => null() !< convergence option
+    integer(I4B), pointer :: iter1 => null() !< max. iterations
+    integer(I4B), pointer :: ilinmeth => null() !< linear solver method
+    integer(I4B), pointer :: iscl => null() !< scaling method
+    integer(I4B), pointer :: iord => null() !< reordering method
+    integer(I4B), pointer :: north => null() !< number of orthogonalizations
+    real(DP), pointer :: relax => null() !< relaxation factor
+    integer(I4B), pointer :: level => null() !< nr. of preconditioner levels
+    real(DP), pointer :: droptol => null() !< drop tolerance for preconditioner
+    integer(I4B), pointer :: ifdparam => null() !< complexity option
+  contains
+    procedure :: init
+    procedure :: preset_config
+    procedure :: read_from_file
+    procedure :: destroy
+  end type
+
+contains
+
+  subroutine init(this, mem_path)
+    use MemoryHelperModule, only: create_mem_path
+    class(ImsLinearSettingsType) :: this !< linear settings
+    character(len=LENMEMPATH) :: mem_path !< solution memory path
+
+    this%memory_path = create_mem_path(mem_path, 'IMSLINEAR')
+
+    call mem_allocate(this%dvclose, 'DVCLOSE', this%memory_path)
+    call mem_allocate(this%rclose, 'RCLOSE', this%memory_path)
+    call mem_allocate(this%icnvgopt, 'ICNVGOPT', this%memory_path)
+    call mem_allocate(this%iter1, 'ITER1', this%memory_path)
+    call mem_allocate(this%ilinmeth, 'ILINMETH', this%memory_path)
+    call mem_allocate(this%iscl, 'ISCL', this%memory_path)
+    call mem_allocate(this%iord, 'IORD', this%memory_path)
+    call mem_allocate(this%north, 'NORTH', this%memory_path)
+    call mem_allocate(this%relax, 'RELAX', this%memory_path)
+    call mem_allocate(this%level, 'LEVEL', this%memory_path)
+    call mem_allocate(this%droptol, 'DROPTOL', this%memory_path)
+    call mem_allocate(this%ifdparam, 'IDFPARAM', this%memory_path)
+
+    ! defaults
+    this%dvclose = DZERO
+    this%rclose = DZERO
+    this%icnvgopt = 0
+    this%iter1 = 0
+    this%ilinmeth = 0
+    this%iscl = 0
+    this%iord = 0
+    this%north = 0
+    this%relax = DZERO
+    this%level = 0
+    this%droptol = DZERO
+    this%ifdparam = 0
+
+  end subroutine init
+
+  !> @brief Set solver pre-configured settings based on complexity option
+  !<
+  subroutine preset_config(this, idfparam)
+    class(ImsLinearSettingsType) :: this !< linear settings
+    integer(I4B) :: idfparam !< complexity option
+
+    this%ifdparam = idfparam
+
+    select case (idfparam)
+    case (1) ! Simple option
+      this%iter1 = 50
+      this%ilinmeth = 1
+      this%iscl = 0
+      this%iord = 0
+      this%dvclose = DEM3
+      this%rclose = DEM1
+      this%relax = DZERO
+      this%level = 0
+      this%droptol = DZERO
+      this%north = 0
+    case (2) ! Moderate
+      this%iter1 = 100
+      this%ilinmeth = 2
+      this%iscl = 0
+      this%iord = 0
+      this%dvclose = DEM2
+      this%rclose = DEM1
+      this%relax = 0.97D0
+      this%level = 0
+      this%droptol = DZERO
+      this%north = 0
+    case (3) ! Complex
+      this%iter1 = 500
+      this%ilinmeth = 2
+      this%iscl = 0
+      this%iord = 0
+      this%dvclose = DEM1
+      this%rclose = DEM1
+      this%relax = DZERO
+      this%level = 5
+      this%droptol = DEM4
+      this%north = 2
+    end select
+
+  end subroutine preset_config
+
+  !> @brief Read the settings for the linear solver from the .ims file,
+  !< overriding a possible pre-set configuration with set_complexity
+  subroutine read_from_file(this, parser, iout)
+    class(ImsLinearSettingsType) :: this !< linear settings
+    type(BlockParserType) :: parser !< block parser
+    integer(I4B) :: iout !< listing file
+    ! local
+    logical(LGP) :: block_found, end_of_block
+    integer(I4B) :: ierr
+    character(len=LINELENGTH) :: errmsg
+    character(len=LINELENGTH) :: warnmsg
+    character(len=LINELENGTH) :: keyword
+    integer(I4B) :: iscaling, iordering
+
+    call parser%GetBlock('LINEAR', block_found, ierr, supportOpenClose=.true., &
+                         blockRequired=.FALSE.)
+
+    if (block_found) then
+      write (iout, '(/1x,a)') 'PROCESSING LINEAR DATA'
+      do
+        call parser%GetNextLine(end_of_block)
+        if (end_of_block) exit
+        call parser%GetStringCaps(keyword)
+        ! -- parse keyword
+        select case (keyword)
+        case ('INNER_DVCLOSE')
+          this%dvclose = parser%GetDouble()
+        case ('INNER_RCLOSE')
+          this%rclose = parser%GetDouble()
+          ! -- look for additional key words
+          call parser%GetStringCaps(keyword)
+          if (keyword == 'STRICT') then
+            this%icnvgopt = 1
+          else if (keyword == 'L2NORM_RCLOSE') then
+            this%icnvgopt = 2
+          else if (keyword == 'RELATIVE_RCLOSE') then
+            this%icnvgopt = 3
+          else if (keyword == 'L2NORM_RELATIVE_RCLOSE') then
+            this%icnvgopt = 4
+          end if
+        case ('INNER_MAXIMUM')
+          this%iter1 = parser%GetInteger()
+        case ('LINEAR_ACCELERATION')
+          call parser%GetStringCaps(keyword)
+          if (keyword .eq. 'CG') then
+            this%ilinmeth = 1
+          else if (keyword .eq. 'BICGSTAB') then
+            this%ilinmeth = 2
+          else
+            this%ilinmeth = 0
+            write (errmsg, '(3a)') &
+              'Unknown IMSLINEAR LINEAR_ACCELERATION method (', &
+              trim(keyword), ').'
+            call store_error(errmsg)
+          end if
+        case ('SCALING_METHOD')
+          call parser%GetStringCaps(keyword)
+          iscaling = 0
+          if (keyword .eq. 'NONE') then
+            iscaling = 0
+          else if (keyword .eq. 'DIAGONAL') then
+            iscaling = 1
+          else if (keyword .eq. 'L2NORM') then
+            iscaling = 2
+          else
+            write (errmsg, '(3a)') &
+              'Unknown IMSLINEAR SCALING_METHOD (', trim(keyword), ').'
+            call store_error(errmsg)
+          end if
+          this%iscl = iscaling
+        case ('RED_BLACK_ORDERING')
+          iordering = 0
+        case ('REORDERING_METHOD')
+          call parser%GetStringCaps(keyword)
+          iordering = 0
+          if (keyword == 'NONE') then
+            iordering = 0
+          else if (keyword == 'RCM') then
+            iordering = 1
+          else if (keyword == 'MD') then
+            iordering = 2
+          else
+            write (errmsg, '(3a)') &
+              'Unknown IMSLINEAR REORDERING_METHOD (', trim(keyword), ').'
+            call store_error(errmsg)
+          end if
+          this%iord = iordering
+        case ('NUMBER_ORTHOGONALIZATIONS')
+          this%north = parser%GetInteger()
+        case ('RELAXATION_FACTOR')
+          this%relax = parser%GetDouble()
+        case ('PRECONDITIONER_LEVELS')
+          this%level = parser%GetInteger()
+          if (this%level < 0) then
+            write (errmsg, '(a,1x,a)') &
+              'IMSLINEAR PRECONDITIONER_LEVELS must be greater than', &
+              'or equal to zero'
+            call store_error(errmsg)
+          end if
+        case ('PRECONDITIONER_DROP_TOLERANCE')
+          this%droptol = parser%GetDouble()
+          if (this%droptol < DZERO) then
+            write (errmsg, '(a,1x,a)') &
+              'IMSLINEAR PRECONDITIONER_DROP_TOLERANCE', &
+              'must be greater than or equal to zero'
+            call store_error(errmsg)
+          end if
+          !
+          ! -- deprecated variables
+        case ('INNER_HCLOSE')
+          this%dvclose = parser%GetDouble()
+          !
+          ! -- create warning message
+          write (warnmsg, '(a)') &
+            'SETTING INNER_DVCLOSE TO INNER_HCLOSE VALUE'
+          !
+          ! -- create deprecation warning
+          call deprecation_warning('LINEAR', 'INNER_HCLOSE', '6.1.1', &
+                                   warnmsg, parser%GetUnit())
+          !
+          ! -- default
+        case default
+          write (errmsg, '(3a)') &
+            'Unknown IMSLINEAR keyword (', trim(keyword), ').'
+          call store_error(errmsg)
+        end select
+      end do
+      write (iout, '(1x,a)') 'END OF LINEAR DATA'
+    else
+      if (this%ifdparam == 0) THEN
+        write (errmsg, '(a)') 'NO LINEAR block detected.'
+        call store_error(errmsg)
+      end if
+    end if
+
+  end subroutine read_from_file
+
+  subroutine destroy(this)
+    class(ImsLinearSettingsType) :: this !< linear settings
+
+    call mem_deallocate(this%dvclose)
+    call mem_deallocate(this%rclose)
+    call mem_deallocate(this%icnvgopt)
+    call mem_deallocate(this%iter1)
+    call mem_deallocate(this%ilinmeth)
+    call mem_deallocate(this%iscl)
+    call mem_deallocate(this%iord)
+    call mem_deallocate(this%north)
+    call mem_deallocate(this%relax)
+    call mem_deallocate(this%level)
+    call mem_deallocate(this%droptol)
+    call mem_deallocate(this%ifdparam)
+
+  end subroutine destroy
+
+end module
diff --git a/src/Solution/LinearMethods/ImsLinearSolver.f90 b/src/Solution/LinearMethods/ImsLinearSolver.f90
index de63b9c8a38..b69a055abbd 100644
--- a/src/Solution/LinearMethods/ImsLinearSolver.f90
+++ b/src/Solution/LinearMethods/ImsLinearSolver.f90
@@ -4,6 +4,9 @@ module ImsLinearSolverModule
   use MatrixBaseModule
   use VectorBaseModule
   use SparseMatrixModule
+  use ImsLinearSettingsModule
+  use ConvergenceSummaryModule
+
   implicit none
   private
 
@@ -12,6 +15,7 @@ module ImsLinearSolverModule
   type, public, extends(LinearSolverBaseType) :: ImsLinearSolverType
   contains
     procedure :: initialize => ims_initialize
+    procedure :: print_summary => ims_print_summary
     procedure :: solve => ims_solve
     procedure :: get_result => ims_get_result
     procedure :: destroy => ims_destroy
@@ -31,16 +35,23 @@ function create_ims_solver() result(solver)
 
   end function create_ims_solver
 
-  subroutine ims_initialize(this, matrix)
+  subroutine ims_initialize(this, matrix, linear_settings, convergence_summary)
     class(ImsLinearSolverType) :: this
     class(MatrixBaseType), pointer :: matrix
+    type(ImsLinearSettingsType), pointer :: linear_settings
+    type(ConvergenceSummaryType), pointer :: convergence_summary
   end subroutine ims_initialize
 
-  subroutine ims_solve(this, kiter, rhs, x)
+  subroutine ims_print_summary(this)
+    class(ImsLinearSolverType) :: this
+  end subroutine ims_print_summary
+
+  subroutine ims_solve(this, kiter, rhs, x, cnvg_summary)
     class(ImsLinearSolverType) :: this
     integer(I4B) :: kiter
     class(VectorBaseType), pointer :: rhs
     class(VectorBaseType), pointer :: x
+    type(ConvergenceSummaryType) :: cnvg_summary
   end subroutine ims_solve
 
   subroutine ims_get_result(this)
diff --git a/src/Solution/LinearMethods/ims8base.f90 b/src/Solution/LinearMethods/ims8base.f90
index 7e927e6d0b7..4c82d9f87af 100644
--- a/src/Solution/LinearMethods/ims8base.f90
+++ b/src/Solution/LinearMethods/ims8base.f90
@@ -9,9 +9,10 @@ MODULE IMSLinearBaseModule
   use KindModule, only: DP, I4B
   use ConstantsModule, only: LINELENGTH, IZERO, &
                              DZERO, DPREC, DEM6, DEM3, DHALF, DONE
-  use GenericUtilitiesModule, only: sim_message, is_same
+  use MathUtilModule, only: is_close
   use BlockParserModule, only: BlockParserType
   use IMSReorderingModule, only: ims_odrv
+  use ConvergenceSummaryModule
 
   IMPLICIT NONE
 
@@ -28,14 +29,13 @@ MODULE IMSLinearBaseModule
   !<
   SUBROUTINE ims_base_cg(ICNVG, ITMAX, INNERIT, &
                          NEQ, NJA, NIAPC, NJAPC, &
-                         IPC, NITERC, ICNVGOPT, NORTH, &
+                         IPC, ICNVGOPT, NORTH, &
                          DVCLOSE, RCLOSE, L2NORM0, EPFACT, &
                          IA0, JA0, A0, IAPC, JAPC, APC, &
                          X, B, D, P, Q, Z, &
                          NJLU, IW, JLU, &
-                         NCONV, CONVNMOD, CONVMODSTART, LOCDV, LOCDR, &
-                         CACCEL, ITINNER, CONVLOCDV, CONVLOCDR, &
-                         DVMAX, DRMAX, CONVDVMAX, CONVDRMAX)
+                         NCONV, CONVNMOD, CONVMODSTART, &
+                         CACCEL, summary)
     ! -- dummy variables
     integer(I4B), INTENT(INOUT) :: ICNVG !< convergence flag (1) non-convergence (0)
     integer(I4B), INTENT(IN) :: ITMAX !< maximum number of inner iterations
@@ -45,7 +45,6 @@ SUBROUTINE ims_base_cg(ICNVG, ITMAX, INNERIT, &
     integer(I4B), INTENT(IN) :: NIAPC !< preconditioner number of rows
     integer(I4B), INTENT(IN) :: NJAPC !< preconditioner number of non-zero entries
     integer(I4B), INTENT(IN) :: IPC !< preconditioner option
-    integer(I4B), INTENT(INOUT) :: NITERC !< total number of inner iterations
     integer(I4B), INTENT(IN) :: ICNVGOPT !< flow convergence criteria option
     integer(I4B), INTENT(IN) :: NORTH !< orthogonalization frequency
     real(DP), INTENT(IN) :: DVCLOSE !< dependent-variable closure criteria
@@ -72,16 +71,8 @@ SUBROUTINE ims_base_cg(ICNVG, ITMAX, INNERIT, &
     integer(I4B), INTENT(IN) :: NCONV !< maximum number of inner iterations in a time step (maxiter * maxinner)
     integer(I4B), INTENT(IN) :: CONVNMOD !< number of models in the solution
     integer(I4B), DIMENSION(CONVNMOD + 1), INTENT(INOUT) :: CONVMODSTART !< pointer to the start of each model in the convmod* arrays
-    integer(I4B), DIMENSION(CONVNMOD), INTENT(INOUT) :: LOCDV !< location of the maximum dependent-variable change in the solution
-    integer(I4B), DIMENSION(CONVNMOD), INTENT(INOUT) :: LOCDR !< location of the maximum flow change in the solution
     character(len=31), DIMENSION(NCONV), INTENT(INOUT) :: CACCEL !< convergence string
-    integer(I4B), DIMENSION(NCONV), INTENT(INOUT) :: ITINNER !< actual number of inner iterations in each Picard iteration
-    integer(I4B), DIMENSION(CONVNMOD, NCONV), INTENT(INOUT) :: CONVLOCDV !< location of the maximum dependent-variable change in each model in the solution
-    integer(I4B), DIMENSION(CONVNMOD, NCONV), INTENT(INOUT) :: CONVLOCDR !< location of the maximum flow change in each model in the solution
-    real(DP), DIMENSION(CONVNMOD), INTENT(INOUT) :: DVMAX !< maximum dependent-variable change in the solution
-    real(DP), DIMENSION(CONVNMOD), INTENT(INOUT) :: DRMAX !< maximum flow change in the solution
-    real(DP), DIMENSION(CONVNMOD, NCONV), INTENT(INOUT) :: CONVDVMAX !< maximum dependent-variable change in each model in the solution
-    real(DP), DIMENSION(CONVNMOD, NCONV), INTENT(INOUT) :: CONVDRMAX !< maximum flow change in each model in the solution
+    type(ConvergenceSummaryType), pointer, intent(in) :: summary !< Convergence summary report
     ! -- local variables
     LOGICAL :: lorth
     logical :: lsame
@@ -108,7 +99,7 @@ SUBROUTINE ims_base_cg(ICNVG, ITMAX, INNERIT, &
     ! -- INNER ITERATION
     INNER: DO iiter = 1, itmax
       INNERIT = INNERIT + 1
-      NITERC = NITERC + 1
+      summary%iter_cnt = summary%iter_cnt + 1
       !
       ! -- APPLY PRECONDITIONER
       SELECT CASE (IPC)
@@ -148,8 +139,8 @@ SUBROUTINE ims_base_cg(ICNVG, ITMAX, INNERIT, &
       rmax = DZERO
       l2norm = DZERO
       DO im = 1, CONVNMOD
-        DVMAX(im) = DZERO
-        DRMAX(im) = DZERO
+        summary%dvmax(im) = DZERO
+        summary%drmax(im) = DZERO
       END DO
       im = 1
       im0 = CONVMODSTART(1)
@@ -170,9 +161,9 @@ SUBROUTINE ims_base_cg(ICNVG, ITMAX, INNERIT, &
           deltax = tv
           xloc = n
         END IF
-        IF (ABS(tv) > ABS(DVMAX(im))) THEN
-          DVMAX(im) = tv
-          LOCDV(im) = n
+        IF (ABS(tv) > ABS(summary%dvmax(im))) THEN
+          summary%dvmax(im) = tv
+          summary%locdv(im) = n
         END IF
         tv = D(n)
         tv = tv - alpha * Q(n)
@@ -181,9 +172,9 @@ SUBROUTINE ims_base_cg(ICNVG, ITMAX, INNERIT, &
           rmax = tv
           rloc = n
         END IF
-        IF (ABS(tv) > ABS(DRMAX(im))) THEN
-          DRMAX(im) = tv
-          LOCDR(im) = n
+        IF (ABS(tv) > ABS(summary%drmax(im))) THEN
+          summary%drmax(im) = tv
+          summary%locdr(im) = n
         END IF
         l2norm = l2norm + tv * tv
       END DO
@@ -191,15 +182,15 @@ SUBROUTINE ims_base_cg(ICNVG, ITMAX, INNERIT, &
       !
       ! -- SAVE SOLVER convergence information dummy variables
       IF (NCONV > 1) THEN !<
-        n = NITERC
+        n = summary%iter_cnt
         WRITE (cval, '(g15.7)') alpha
         CACCEL(n) = cval
-        ITINNER(n) = iiter
+        summary%itinner(n) = iiter
         DO im = 1, CONVNMOD
-          CONVLOCDV(im, n) = LOCDV(im)
-          CONVLOCDR(im, n) = LOCDR(im)
-          CONVDVMAX(im, n) = DVMAX(im)
-          CONVDRMAX(im, n) = DRMAX(im)
+          summary%convlocdv(im, n) = summary%locdv(im)
+          summary%convlocdr(im, n) = summary%locdr(im)
+          summary%convdvmax(im, n) = summary%dvmax(im)
+          summary%convdrmax(im, n) = summary%drmax(im)
         END DO
       END IF
       !
@@ -220,7 +211,7 @@ SUBROUTINE ims_base_cg(ICNVG, ITMAX, INNERIT, &
       IF (ICNVG .NE. 0) EXIT INNER
       !
       ! -- CHECK THAT CURRENT AND PREVIOUS rho ARE DIFFERENT
-      lsame = is_same(rho, rho0)
+      lsame = is_close(rho, rho0)
       IF (lsame) THEN
         EXIT INNER
       END IF
@@ -258,15 +249,14 @@ END SUBROUTINE ims_base_cg
   !<
   SUBROUTINE ims_base_bcgs(ICNVG, ITMAX, INNERIT, &
                            NEQ, NJA, NIAPC, NJAPC, &
-                           IPC, NITERC, ICNVGOPT, NORTH, ISCL, DSCALE, &
+                           IPC, ICNVGOPT, NORTH, ISCL, DSCALE, &
                            DVCLOSE, RCLOSE, L2NORM0, EPFACT, &
                            IA0, JA0, A0, IAPC, JAPC, APC, &
                            X, B, D, P, Q, &
                            T, V, DHAT, PHAT, QHAT, &
                            NJLU, IW, JLU, &
-                           NCONV, CONVNMOD, CONVMODSTART, LOCDV, LOCDR, &
-                           CACCEL, ITINNER, CONVLOCDV, CONVLOCDR, &
-                           DVMAX, DRMAX, CONVDVMAX, CONVDRMAX)
+                           NCONV, CONVNMOD, CONVMODSTART, &
+                           CACCEL, summary)
     ! -- dummy variables
     integer(I4B), INTENT(INOUT) :: ICNVG !< convergence flag (1) non-convergence (0)
     integer(I4B), INTENT(IN) :: ITMAX !< maximum number of inner iterations
@@ -276,7 +266,6 @@ SUBROUTINE ims_base_bcgs(ICNVG, ITMAX, INNERIT, &
     integer(I4B), INTENT(IN) :: NIAPC !< preconditioner number of rows
     integer(I4B), INTENT(IN) :: NJAPC !< preconditioner number of non-zero entries
     integer(I4B), INTENT(IN) :: IPC !< preconditioner option
-    integer(I4B), INTENT(INOUT) :: NITERC !< total number of inner iterations
     integer(I4B), INTENT(IN) :: ICNVGOPT !< flow convergence criteria option
     integer(I4B), INTENT(IN) :: NORTH !< orthogonalization frequency
     integer(I4B), INTENT(IN) :: ISCL !< scaling option
@@ -309,16 +298,8 @@ SUBROUTINE ims_base_bcgs(ICNVG, ITMAX, INNERIT, &
     integer(I4B), INTENT(IN) :: NCONV !< maximum number of inner iterations in a time step (maxiter * maxinner)
     integer(I4B), INTENT(IN) :: CONVNMOD !< number of models in the solution
     integer(I4B), DIMENSION(CONVNMOD + 1), INTENT(INOUT) :: CONVMODSTART !< pointer to the start of each model in the convmod* arrays
-    integer(I4B), DIMENSION(CONVNMOD), INTENT(INOUT) :: LOCDV !< location of the maximum dependent-variable change in the solution
-    integer(I4B), DIMENSION(CONVNMOD), INTENT(INOUT) :: LOCDR !< location of the maximum flow change in the solution
     character(len=31), DIMENSION(NCONV), INTENT(INOUT) :: CACCEL !< convergence string
-    integer(I4B), DIMENSION(NCONV), INTENT(INOUT) :: ITINNER !< actual number of inner iterations in each Picard iteration
-    integer(I4B), DIMENSION(CONVNMOD, NCONV), INTENT(INOUT) :: CONVLOCDV !< location of the maximum dependent-variable change in each model in the solution
-    integer(I4B), DIMENSION(CONVNMOD, NCONV), INTENT(INOUT) :: CONVLOCDR !< location of the maximum flow change in each model in the solution
-    real(DP), DIMENSION(CONVNMOD), INTENT(INOUT) :: DVMAX !< maximum dependent-variable change in the solution
-    real(DP), DIMENSION(CONVNMOD), INTENT(INOUT) :: DRMAX !< maximum flow change in the solution
-    real(DP), DIMENSION(CONVNMOD, NCONV), INTENT(INOUT) :: CONVDVMAX !< maximum dependent-variable change in each model in the solution
-    real(DP), DIMENSION(CONVNMOD, NCONV), INTENT(INOUT) :: CONVDRMAX !< maximum flow change in each model in the solution
+    type(ConvergenceSummaryType), pointer, intent(in) :: summary !< Convergence summary report
     ! -- local variables
     LOGICAL :: LORTH
     logical :: lsame
@@ -357,7 +338,7 @@ SUBROUTINE ims_base_bcgs(ICNVG, ITMAX, INNERIT, &
     ! -- INNER ITERATION
     INNER: DO iiter = 1, itmax
       INNERIT = INNERIT + 1
-      NITERC = NITERC + 1
+      summary%iter_cnt = summary%iter_cnt + 1
       !
       ! -- CALCULATE rho
       rho = ddot(NEQ, DHAT, 1, D, 1)
@@ -451,8 +432,8 @@ SUBROUTINE ims_base_bcgs(ICNVG, ITMAX, INNERIT, &
       rmax = DZERO
       l2norm = DZERO
       DO im = 1, CONVNMOD
-        DVMAX(im) = DZERO
-        DRMAX(im) = DZERO
+        summary%dvmax(im) = DZERO
+        summary%drmax(im) = DZERO
       END DO
       im = 1
       im0 = CONVMODSTART(1)
@@ -476,9 +457,9 @@ SUBROUTINE ims_base_bcgs(ICNVG, ITMAX, INNERIT, &
           deltax = tv
           xloc = n
         END IF
-        IF (ABS(tv) > ABS(DVMAX(im))) THEN
-          DVMAX(im) = tv
-          LOCDV(im) = n
+        IF (ABS(tv) > ABS(summary%dvmax(im))) THEN
+          summary%dvmax(im) = tv
+          summary%locdv(im) = n
         END IF
         !
         ! -- RESIDUAL
@@ -491,9 +472,9 @@ SUBROUTINE ims_base_bcgs(ICNVG, ITMAX, INNERIT, &
           rmax = tv
           rloc = n
         END IF
-        IF (ABS(tv) > ABS(DRMAX(im))) THEN
-          DRMAX(im) = tv
-          LOCDR(im) = n
+        IF (ABS(tv) > ABS(summary%drmax(im))) THEN
+          summary%drmax(im) = tv
+          summary%locdr(im) = n
         END IF
         l2norm = l2norm + tv * tv
       END DO
@@ -501,16 +482,16 @@ SUBROUTINE ims_base_bcgs(ICNVG, ITMAX, INNERIT, &
       !
       ! -- SAVE SOLVER convergence information dummy variables
       IF (NCONV > 1) THEN !<
-        n = NITERC
+        n = summary%iter_cnt
         WRITE (cval1, '(g15.7)') alpha
         WRITE (cval2, '(g15.7)') omega
         CACCEL(n) = trim(adjustl(cval1))//','//trim(adjustl(cval2))
-        ITINNER(n) = iiter
+        summary%itinner(n) = iiter
         DO im = 1, CONVNMOD
-          CONVLOCDV(im, n) = LOCDV(im)
-          CONVLOCDR(im, n) = LOCDR(im)
-          CONVDVMAX(im, n) = DVMAX(im)
-          CONVDRMAX(im, n) = DRMAX(im)
+          summary%convdvmax(im, n) = summary%dvmax(im)
+          summary%convlocdv(im, n) = summary%locdv(im)
+          summary%convdrmax(im, n) = summary%drmax(im)
+          summary%convlocdr(im, n) = summary%locdr(im)
         END DO
       END IF
       !
@@ -532,15 +513,15 @@ SUBROUTINE ims_base_bcgs(ICNVG, ITMAX, INNERIT, &
       !
       ! -- CHECK THAT CURRENT AND PREVIOUS rho, alpha, AND omega ARE
       !    DIFFERENT
-      lsame = is_same(rho, rho0)
+      lsame = is_close(rho, rho0)
       IF (lsame) THEN
         EXIT INNER
       END IF
-      lsame = is_same(alpha, alpha0)
+      lsame = is_close(alpha, alpha0)
       IF (lsame) THEN
         EXIT INNER
       END IF
-      lsame = is_same(omega, omega0)
+      lsame = is_close(omega, omega0)
       IF (lsame) THEN
         EXIT INNER
       END IF
diff --git a/src/Solution/LinearMethods/ims8linear.f90 b/src/Solution/LinearMethods/ims8linear.f90
index ecb7c2f16d7..4838ff1cd88 100644
--- a/src/Solution/LinearMethods/ims8linear.f90
+++ b/src/Solution/LinearMethods/ims8linear.f90
@@ -6,13 +6,14 @@ MODULE IMSLinearModule
                              DEM8, DEM6, DEM5, DEM4, DEM3, DEM2, DEM1, &
                              DHALF, DONE, DTWO, &
                              VDEBUG
-  use GenericUtilitiesModule, only: sim_message
   use IMSLinearBaseModule, only: ims_base_cg, ims_base_bcgs, &
                                  ims_base_pccrs, ims_base_calc_order, &
                                  ims_base_scale, ims_base_pcu, &
                                  ims_base_residual
   use BlockParserModule, only: BlockParserType
   use MatrixBaseModule
+  use ConvergenceSummaryModule
+  use ImsLinearSettingsModule
 
   IMPLICIT NONE
   private
@@ -21,26 +22,28 @@ MODULE IMSLinearModule
     character(len=LENMEMPATH) :: memoryPath !< the path for storing variables in the memory manager
     integer(I4B), POINTER :: iout => NULL() !< simulation listing file unit
     integer(I4B), POINTER :: IPRIMS => NULL() !< print flag
-    integer(I4B), POINTER :: ILINMETH => NULL() !< linear accelerator (1) cg, (2) bicgstab
-    integer(I4B), POINTER :: ITER1 => NULL() !< maximum inner iterations
+    ! input variables (pointing to fields in input structure)
+    real(DP), pointer :: DVCLOSE => null() !< dependent variable closure criterion
+    real(DP), pointer :: RCLOSE => null() !< residual closure criterion
+    integer(I4B), pointer :: ICNVGOPT => null() !< convergence option
+    integer(I4B), pointer :: ITER1 => null() !< max. iterations
+    integer(I4B), pointer :: ILINMETH => null() !< linear solver method
+    integer(I4B), pointer :: iSCL => null() !< scaling method
+    integer(I4B), pointer :: IORD => null() !< reordering method
+    integer(I4B), pointer :: NORTH => null() !< number of orthogonalizations
+    real(DP), pointer :: RELAX => null() !< relaxation factor
+    integer(I4B), pointer :: LEVEL => null() !< nr. of preconditioner levels
+    real(DP), pointer :: DROPTOL => null() !< drop tolerance for preconditioner
+    !
     integer(I4B), POINTER :: IPC => NULL() !< preconditioner flag
-    integer(I4B), POINTER :: ISCL => NULL() !< scaling flag
-    integer(I4B), POINTER :: IORD => NULL() !< reordering flag
-    integer(I4B), POINTER :: NORTH => NULL() !< orthogonalization interval
-    integer(I4B), POINTER :: ICNVGOPT => NULL() !< rclose convergence option flag
     integer(I4B), POINTER :: IACPC => NULL() !< preconditioner CRS row pointers
     integer(I4B), POINTER :: NITERC => NULL() !<
     integer(I4B), POINTER :: NIABCGS => NULL() !< size of working vectors for BCGS linear accelerator
     integer(I4B), POINTER :: NIAPC => NULL() !< preconditioner number of rows
     integer(I4B), POINTER :: NJAPC => NULL() !< preconditioner number of non-zero entries
-    real(DP), POINTER :: DVCLOSE => NULL() !< dependent variable convergence criteria
-    real(DP), POINTER :: RCLOSE => NULL() !< flow convergence criteria
-    real(DP), POINTER :: RELAX => NULL() !< preconditioner MILU0/MILUT relaxation factor
     real(DP), POINTER :: EPFACT => NULL() !< factor for decreasing convergence criteria in seubsequent Picard iterations
     real(DP), POINTER :: L2NORM0 => NULL() !< initial L2 norm
     ! -- ilut variables
-    integer(I4B), POINTER :: LEVEL => NULL() !< preconditioner number of levels
-    real(DP), POINTER :: DROPTOL => NULL() !< preconditioner drop tolerance
     integer(I4B), POINTER :: NJLU => NULL() !< length of jlu work vector
     integer(I4B), POINTER :: NJW => NULL() !< length of jw work vector
     integer(I4B), POINTER :: NWLU => NULL() !< length of wlu work vector
@@ -104,8 +107,8 @@ MODULE IMSLinearModule
     !!  Allocate storage for linear accelerators and read data
     !!
   !<
-  SUBROUTINE imslinear_ar(this, NAME, parser, IOUT, IPRIMS, MXITER, IFDPARAM, &
-                          IMSLINEARM, NEQ, matrix, RHS, X, NINNER, LFINDBLOCK)
+  SUBROUTINE imslinear_ar(this, NAME, IOUT, IPRIMS, MXITER, &
+                          NEQ, matrix, RHS, X, linear_settings)
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     use MemoryHelperModule, only: create_mem_path
@@ -114,49 +117,40 @@ SUBROUTINE imslinear_ar(this, NAME, parser, IOUT, IPRIMS, MXITER, IFDPARAM, &
     ! -- dummy variables
     CLASS(ImsLinearDataType), INTENT(INOUT) :: this !< ImsLinearDataType instance
     CHARACTER(LEN=LENSOLUTIONNAME), INTENT(IN) :: NAME !< solution name
-    type(BlockParserType) :: parser !< block parser
     integer(I4B), INTENT(IN) :: IOUT !< simulation listing file unit
     integer(I4B), TARGET, INTENT(IN) :: IPRIMS !< print option
     integer(I4B), INTENT(IN) :: MXITER !< maximum outer iterations
-    integer(I4B), INTENT(IN) :: IFDPARAM !< complexity option
-    integer(I4B), INTENT(INOUT) :: IMSLINEARM !< linear method option (1) CG (2) BICGSTAB
     integer(I4B), TARGET, INTENT(IN) :: NEQ !< number of equations
     class(MatrixBaseType), pointer :: matrix
     real(DP), DIMENSION(NEQ), TARGET, INTENT(INOUT) :: RHS !< right-hand side
     real(DP), DIMENSION(NEQ), TARGET, INTENT(INOUT) :: X !< dependent variables
-    integer(I4B), TARGET, INTENT(INOUT) :: NINNER !< maximum number of inner iterations
-    integer(I4B), INTENT(IN), OPTIONAL :: LFINDBLOCK !< flag indicating if the linear block is present (1) or missing (0)
-
+    type(ImsLinearSettingsType), pointer :: linear_settings !< the settings form the IMS file
     ! -- local variables
-    LOGICAL :: lreaddata
     character(len=LINELENGTH) :: errmsg
-    character(len=LINELENGTH) :: warnmsg
-    character(len=LINELENGTH) :: keyword
     integer(I4B) :: i, n
     integer(I4B) :: i0
     integer(I4B) :: iscllen, iolen
-    integer(I4B) :: ierr
-    real(DP) :: r
-    logical :: isfound, endOfBlock
     integer(I4B) :: ijlu
     integer(I4B) :: ijw
     integer(I4B) :: iwlu
     integer(I4B) :: iwk
     !
-    ! -- SET LREADDATA
-    IF (PRESENT(LFINDBLOCK)) THEN
-      IF (LFINDBLOCK < 1) THEN
-        lreaddata = .FALSE.
-      ELSE
-        lreaddata = .TRUE.
-      END IF
-    ELSE
-      lreaddata = .TRUE.
-    END IF
-    !
     ! -- DEFINE NAME
     this%memoryPath = create_mem_path(name, 'IMSLINEAR')
     !
+    ! -- SET pointers to IMS settings
+    this%DVCLOSE => linear_settings%dvclose
+    this%RCLOSE => linear_settings%rclose
+    this%ICNVGOPT => linear_settings%icnvgopt
+    this%ITER1 => linear_settings%iter1
+    this%ILINMETH => linear_settings%ilinmeth
+    this%iSCL => linear_settings%iscl
+    this%IORD => linear_settings%iord
+    this%NORTH => linear_settings%north
+    this%RELAX => linear_settings%relax
+    this%LEVEL => linear_settings%level
+    this%DROPTOL => linear_settings%droptol
+    !
     ! -- SET POINTERS TO SOLUTION STORAGE
     this%IPRIMS => IPRIMS
     this%NEQ => NEQ
@@ -173,165 +167,15 @@ SUBROUTINE imslinear_ar(this, NAME, parser, IOUT, IPRIMS, MXITER, IFDPARAM, &
     this%iout = iout
     !
     ! -- DEFAULT VALUES
-    this%IORD = 0
-    this%ISCL = 0
     this%IPC = 0
-    this%LEVEL = 0
     !
-    ! -- TRANSFER COMMON VARIABLES FROM IMS TO IMSLINEAR
-    this%ILINMETH = 0
-
     this%IACPC = 0
-    this%RELAX = DZERO !0.97
-
-    this%DROPTOL = DZERO
-
-    this%NORTH = 0
-
-    this%ICNVGOPT = 0
     !
     ! -- PRINT A MESSAGE IDENTIFYING IMSLINEAR SOLVER PACKAGE
     write (iout, 2000)
 02000 FORMAT(1X, /1X, 'IMSLINEAR -- UNSTRUCTURED LINEAR SOLUTION', &
            ' PACKAGE, VERSION 8, 04/28/2017')
     !
-    ! -- SET DEFAULT IMSLINEAR PARAMETERS
-    CALL this%SET_IMSLINEAR_INPUT(IFDPARAM)
-    NINNER = this%iter1
-    !
-    ! -- get IMSLINEAR block
-    if (lreaddata) then
-      call parser%GetBlock('LINEAR', isfound, ierr, &
-                           supportOpenClose=.true., blockRequired=.FALSE.)
-    else
-      isfound = .FALSE.
-    end if
-    !
-    ! -- parse IMSLINEAR block if detected
-    if (isfound) then
-      write (iout, '(/1x,a)') 'PROCESSING LINEAR DATA'
-      do
-        call parser%GetNextLine(endOfBlock)
-        if (endOfBlock) exit
-        call parser%GetStringCaps(keyword)
-        ! -- parse keyword
-        select case (keyword)
-        case ('INNER_DVCLOSE')
-          this%DVCLOSE = parser%GetDouble()
-        case ('INNER_RCLOSE')
-          this%rclose = parser%GetDouble()
-          ! -- look for additional key words
-          call parser%GetStringCaps(keyword)
-          if (keyword == 'STRICT') then
-            this%ICNVGOPT = 1
-          else if (keyword == 'L2NORM_RCLOSE') then
-            this%ICNVGOPT = 2
-          else if (keyword == 'RELATIVE_RCLOSE') then
-            this%ICNVGOPT = 3
-          else if (keyword == 'L2NORM_RELATIVE_RCLOSE') then
-            this%ICNVGOPT = 4
-          end if
-        case ('INNER_MAXIMUM')
-          i = parser%GetInteger()
-          this%iter1 = i
-          NINNER = i
-        case ('LINEAR_ACCELERATION')
-          call parser%GetStringCaps(keyword)
-          if (keyword .eq. 'CG') then
-            this%ILINMETH = 1
-          else if (keyword .eq. 'BICGSTAB') then
-            this%ILINMETH = 2
-          else
-            this%ILINMETH = 0
-            write (errmsg, '(3a)') &
-              'Unknown IMSLINEAR LINEAR_ACCELERATION method (', &
-              trim(keyword), ').'
-            call store_error(errmsg)
-          end if
-        case ('SCALING_METHOD')
-          call parser%GetStringCaps(keyword)
-          i = 0
-          if (keyword .eq. 'NONE') then
-            i = 0
-          else if (keyword .eq. 'DIAGONAL') then
-            i = 1
-          else if (keyword .eq. 'L2NORM') then
-            i = 2
-          else
-            write (errmsg, '(3a)') &
-              'Unknown IMSLINEAR SCALING_METHOD (', trim(keyword), ').'
-            call store_error(errmsg)
-          end if
-          this%ISCL = i
-        case ('RED_BLACK_ORDERING')
-          i = 0
-        case ('REORDERING_METHOD')
-          call parser%GetStringCaps(keyword)
-          i = 0
-          if (keyword == 'NONE') then
-            i = 0
-          else if (keyword == 'RCM') then
-            i = 1
-          else if (keyword == 'MD') then
-            i = 2
-          else
-            write (errmsg, '(3a)') &
-              'Unknown IMSLINEAR REORDERING_METHOD (', trim(keyword), ').'
-            call store_error(errmsg)
-          end if
-          this%IORD = i
-        case ('NUMBER_ORTHOGONALIZATIONS')
-          this%north = parser%GetInteger()
-        case ('RELAXATION_FACTOR')
-          this%relax = parser%GetDouble()
-        case ('PRECONDITIONER_LEVELS')
-          i = parser%GetInteger()
-          this%level = i
-          if (i < 0) then
-            write (errmsg, '(a,1x,a)') &
-              'IMSLINEAR PRECONDITIONER_LEVELS must be greater than', &
-              'or equal to zero'
-            call store_error(errmsg)
-          end if
-        case ('PRECONDITIONER_DROP_TOLERANCE')
-          r = parser%GetDouble()
-          this%DROPTOL = r
-          if (r < DZERO) then
-            write (errmsg, '(a,1x,a)') &
-              'IMSLINEAR PRECONDITIONER_DROP_TOLERANCE', &
-              'must be greater than or equal to zero'
-            call store_error(errmsg)
-          end if
-          !
-          ! -- deprecated variables
-        case ('INNER_HCLOSE')
-          this%DVCLOSE = parser%GetDouble()
-          !
-          ! -- create warning message
-          write (warnmsg, '(a)') &
-            'SETTING INNER_DVCLOSE TO INNER_HCLOSE VALUE'
-          !
-          ! -- create deprecation warning
-          call deprecation_warning('LINEAR', 'INNER_HCLOSE', '6.1.1', &
-                                   warnmsg, parser%GetUnit())
-          !
-          ! -- default
-        case default
-          write (errmsg, '(3a)') &
-            'Unknown IMSLINEAR keyword (', trim(keyword), ').'
-          call store_error(errmsg)
-        end select
-      end do
-      write (iout, '(1x,a)') 'END OF LINEAR DATA'
-    else
-      if (IFDPARAM == 0) THEN
-        write (errmsg, '(a)') 'NO LINEAR block detected.'
-        call store_error(errmsg)
-      end if
-    end if
-
-    IMSLINEARM = this%ILINMETH
-    !
     ! -- DETERMINE PRECONDITIONER
     IF (this%LEVEL > 0 .OR. this%DROPTOL > DZERO) THEN
       this%IPC = 3
@@ -372,11 +216,6 @@ SUBROUTINE imslinear_ar(this, NAME, parser, IOUT, IPRIMS, MXITER, IFDPARAM, &
       call store_error(errmsg)
     END IF
     !
-    ! -- CHECK FOR ERRORS IN IMSLINEAR
-    if (count_errors() > 0) then
-      call parser%StoreErrorUnit()
-    end if
-    !
     ! -- INITIALIZE IMSLINEAR VARIABLES
     this%NITERC = 0
     !
@@ -658,50 +497,28 @@ subroutine allocate_scalars(this)
     !
     ! -- allocate scalars
     call mem_allocate(this%iout, 'IOUT', this%memoryPath)
-    call mem_allocate(this%ilinmeth, 'ILINMETH', this%memoryPath)
-    call mem_allocate(this%iter1, 'ITER1', this%memoryPath)
     call mem_allocate(this%ipc, 'IPC', this%memoryPath)
-    call mem_allocate(this%iscl, 'ISCL', this%memoryPath)
-    call mem_allocate(this%iord, 'IORD', this%memoryPath)
-    call mem_allocate(this%north, 'NORTH', this%memoryPath)
-    call mem_allocate(this%icnvgopt, 'ICNVGOPT', this%memoryPath)
     call mem_allocate(this%iacpc, 'IACPC', this%memoryPath)
     call mem_allocate(this%niterc, 'NITERC', this%memoryPath)
     call mem_allocate(this%niabcgs, 'NIABCGS', this%memoryPath)
     call mem_allocate(this%niapc, 'NIAPC', this%memoryPath)
     call mem_allocate(this%njapc, 'NJAPC', this%memoryPath)
-    call mem_allocate(this%dvclose, 'DVCLOSE', this%memoryPath)
-    call mem_allocate(this%rclose, 'RCLOSE', this%memoryPath)
-    call mem_allocate(this%relax, 'RELAX', this%memoryPath)
     call mem_allocate(this%epfact, 'EPFACT', this%memoryPath)
     call mem_allocate(this%l2norm0, 'L2NORM0', this%memoryPath)
-    call mem_allocate(this%droptol, 'DROPTOL', this%memoryPath)
-    call mem_allocate(this%level, 'LEVEL', this%memoryPath)
     call mem_allocate(this%njlu, 'NJLU', this%memoryPath)
     call mem_allocate(this%njw, 'NJW', this%memoryPath)
     call mem_allocate(this%nwlu, 'NWLU', this%memoryPath)
     !
     ! -- initialize scalars
     this%iout = 0
-    this%ilinmeth = 0
-    this%iter1 = 0
     this%ipc = 0
-    this%iscl = 0
-    this%iord = 0
-    this%north = 0
-    this%icnvgopt = 0
     this%iacpc = 0
     this%niterc = 0
     this%niabcgs = 0
     this%niapc = 0
     this%njapc = 0
-    this%dvclose = DZERO
-    this%rclose = DZERO
-    this%relax = DZERO
     this%epfact = DZERO
     this%l2norm0 = 0
-    this%droptol = DZERO
-    this%level = 0
     this%njlu = 0
     this%njw = 0
     this%nwlu = 0
@@ -750,25 +567,14 @@ subroutine imslinear_da(this)
     !
     ! -- scalars
     call mem_deallocate(this%iout)
-    call mem_deallocate(this%ilinmeth)
-    call mem_deallocate(this%iter1)
     call mem_deallocate(this%ipc)
-    call mem_deallocate(this%iscl)
-    call mem_deallocate(this%iord)
-    call mem_deallocate(this%north)
-    call mem_deallocate(this%icnvgopt)
     call mem_deallocate(this%iacpc)
     call mem_deallocate(this%niterc)
     call mem_deallocate(this%niabcgs)
     call mem_deallocate(this%niapc)
     call mem_deallocate(this%njapc)
-    call mem_deallocate(this%dvclose)
-    call mem_deallocate(this%rclose)
-    call mem_deallocate(this%relax)
     call mem_deallocate(this%epfact)
     call mem_deallocate(this%l2norm0)
-    call mem_deallocate(this%droptol)
-    call mem_deallocate(this%level)
     call mem_deallocate(this%njlu)
     call mem_deallocate(this%njw)
     call mem_deallocate(this%nwlu)
@@ -855,9 +661,8 @@ END SUBROUTINE imslinear_set_input
     !!
   !<
   SUBROUTINE imslinear_ap(this, ICNVG, KSTP, KITER, IN_ITER, &
-                          NCONV, CONVNMOD, CONVMODSTART, LOCDV, LOCDR, &
-                          CACCEL, ITINNER, CONVLOCDV, CONVLOCDR, &
-                          DVMAX, DRMAX, CONVDVMAX, CONVDRMAX)
+                          NCONV, CONVNMOD, CONVMODSTART, &
+                          CACCEL, summary)
     ! -- modules
     USE SimModule
     ! -- dummy variables
@@ -870,16 +675,8 @@ SUBROUTINE imslinear_ap(this, ICNVG, KSTP, KITER, IN_ITER, &
     integer(I4B), INTENT(IN) :: NCONV !<
     integer(I4B), INTENT(IN) :: CONVNMOD !<
     integer(I4B), DIMENSION(CONVNMOD + 1), INTENT(INOUT) :: CONVMODSTART !<
-    integer(I4B), DIMENSION(CONVNMOD), INTENT(INOUT) :: LOCDV !<
-    integer(I4B), DIMENSION(CONVNMOD), INTENT(INOUT) :: LOCDR !<
     character(len=31), DIMENSION(NCONV), INTENT(INOUT) :: CACCEL !<
-    integer(I4B), DIMENSION(NCONV), INTENT(INOUT) :: ITINNER !<
-    integer(I4B), DIMENSION(CONVNMOD, NCONV), INTENT(INOUT) :: CONVLOCDV !<
-    integer(I4B), DIMENSION(CONVNMOD, NCONV), INTENT(INOUT) :: CONVLOCDR !<
-    real(DP), DIMENSION(CONVNMOD), INTENT(INOUT) :: DVMAX !<
-    real(DP), DIMENSION(CONVNMOD), INTENT(INOUT) :: DRMAX !<
-    real(DP), DIMENSION(CONVNMOD, NCONV), INTENT(INOUT) :: CONVDVMAX !<
-    real(DP), DIMENSION(CONVNMOD, NCONV), INTENT(INOUT) :: CONVDRMAX !<
+    type(ConvergenceSummaryType), pointer, intent(in) :: summary !< Convergence summary report
     ! -- local variables
     integer(I4B) :: n
     integer(I4B) :: innerit
@@ -932,7 +729,10 @@ SUBROUTINE imslinear_ap(this, ICNVG, KSTP, KITER, IN_ITER, &
                       this%NWLU, this%JLU, this%JW, this%WLU)
     !
     ! -- INITIALIZE SOLUTION VARIABLE AND ARRAYS
-    IF (KITER == 1) this%NITERC = 0
+    IF (KITER == 1) then
+      this%NITERC = 0
+      summary%iter_cnt = 0
+    end if
     irc = 1
     ICNVG = 0
     DO n = 1, this%NEQ
@@ -958,21 +758,20 @@ SUBROUTINE imslinear_ap(this, ICNVG, KSTP, KITER, IN_ITER, &
     IF (this%ILINMETH == 1) THEN
       CALL ims_base_cg(ICNVG, itmax, innerit, &
                        this%NEQ, this%NJA, this%NIAPC, this%NJAPC, &
-                       this%IPC, this%NITERC, this%ICNVGOPT, this%NORTH, &
+                       this%IPC, this%ICNVGOPT, this%NORTH, &
                        this%DVCLOSE, this%RCLOSE, this%L2NORM0, &
                        this%EPFACT, this%IA0, this%JA0, this%A0, &
                        this%IAPC, this%JAPC, this%APC, &
                        this%X, this%RHS, this%D, this%P, this%Q, this%Z, &
                        this%NJLU, this%IW, this%JLU, &
-                       NCONV, CONVNMOD, CONVMODSTART, LOCDV, LOCDR, &
-                       CACCEL, ITINNER, CONVLOCDV, CONVLOCDR, &
-                       DVMAX, DRMAX, CONVDVMAX, CONVDRMAX)
+                       NCONV, CONVNMOD, CONVMODSTART, &
+                       CACCEL, summary)
       !
       ! -- SOLUTION BY THE BICONJUGATE GRADIENT STABILIZED METHOD
     ELSE IF (this%ILINMETH == 2) THEN
       CALL ims_base_bcgs(ICNVG, itmax, innerit, &
                          this%NEQ, this%NJA, this%NIAPC, this%NJAPC, &
-                         this%IPC, this%NITERC, this%ICNVGOPT, this%NORTH, &
+                         this%IPC, this%ICNVGOPT, this%NORTH, &
                          this%ISCL, this%DSCALE, &
                          this%DVCLOSE, this%RCLOSE, this%L2NORM0, &
                          this%EPFACT, this%IA0, this%JA0, this%A0, &
@@ -980,9 +779,8 @@ SUBROUTINE imslinear_ap(this, ICNVG, KSTP, KITER, IN_ITER, &
                          this%X, this%RHS, this%D, this%P, this%Q, &
                          this%T, this%V, this%DHAT, this%PHAT, this%QHAT, &
                          this%NJLU, this%IW, this%JLU, &
-                         NCONV, CONVNMOD, CONVMODSTART, LOCDV, LOCDR, &
-                         CACCEL, ITINNER, CONVLOCDV, CONVLOCDR, &
-                         DVMAX, DRMAX, CONVDVMAX, CONVDRMAX)
+                         NCONV, CONVNMOD, CONVMODSTART, &
+                         CACCEL, summary)
     END IF
     !
     ! -- BACK PERMUTE AMAT, SOLUTION, AND RHS
diff --git a/src/Solution/LinearSolverBase.f90 b/src/Solution/LinearSolverBase.f90
index 3bb8566d9c3..afa5eef722c 100644
--- a/src/Solution/LinearSolverBase.f90
+++ b/src/Solution/LinearSolverBase.f90
@@ -2,6 +2,9 @@ module LinearSolverBaseModule
   use KindModule, only: I4B, DP
   use MatrixBaseModule
   use VectorBaseModule
+  use ImsLinearSettingsModule
+  use ConvergenceSummaryModule
+
   implicit none
   private
 
@@ -16,6 +19,7 @@ module LinearSolverBaseModule
     integer(I4B) :: is_converged
   contains
     procedure(initialize_if), deferred :: initialize
+    procedure(print_summary_if), deferred :: print_summary
     procedure(solve_if), deferred :: solve
     procedure(get_result_if), deferred :: get_result
     procedure(destroy_if), deferred :: destroy
@@ -24,17 +28,25 @@ module LinearSolverBaseModule
   end type LinearSolverBaseType
 
   abstract interface
-    subroutine initialize_if(this, matrix)
-      import LinearSolverBaseType, MatrixBaseType
+    subroutine initialize_if(this, matrix, linear_settings, convergence_summary)
+      import LinearSolverBaseType, MatrixBaseType, &
+        ImsLinearSettingsType, ConvergenceSummaryType
       class(LinearSolverBaseType) :: this
       class(MatrixBaseType), pointer :: matrix
+      type(ImsLinearSettingsType), pointer :: linear_settings
+      type(ConvergenceSummaryType), pointer :: convergence_summary
+    end subroutine
+    subroutine print_summary_if(this)
+      import LinearSolverBaseType
+      class(LinearSolverBaseType) :: this
     end subroutine
-    subroutine solve_if(this, kiter, rhs, x)
-      import LinearSolverBaseType, I4B, VectorBaseType
+    subroutine solve_if(this, kiter, rhs, x, cnvg_summary)
+      import LinearSolverBaseType, I4B, VectorBaseType, ConvergenceSummaryType
       class(LinearSolverBaseType) :: this
       integer(I4B) :: kiter
       class(VectorBaseType), pointer :: rhs
       class(VectorBaseType), pointer :: x
+      type(ConvergenceSummaryType) :: cnvg_summary
     end subroutine
     subroutine get_result_if(this)
       import LinearSolverBaseType
diff --git a/src/Solution/NumericalSolution.f90 b/src/Solution/NumericalSolution.f90
index 1641c57b48e..41bc43e576b 100644
--- a/src/Solution/NumericalSolution.f90
+++ b/src/Solution/NumericalSolution.f90
@@ -2,6 +2,7 @@
 
 module NumericalSolutionModule
   use KindModule, only: DP, I4B, LGP
+  use ErrorUtilModule, only: pstop
   use TimerModule, only: code_timer
   use ConstantsModule, only: LINELENGTH, LENSOLUTIONNAME, LENPAKLOC, &
                              DPREC, DZERO, DEM20, DEM15, DEM6, &
@@ -12,14 +13,15 @@ module NumericalSolutionModule
                              LENMEMPATH
   use MemoryHelperModule, only: create_mem_path
   use TableModule, only: TableType, table_cr
-  use GenericUtilitiesModule, only: is_same, sim_message, stop_with_error
+  Use MessageModule, only: write_message
+  use MathUtilModule, only: is_close
   use VersionModule, only: IDEVELOPMODE
   use BaseModelModule, only: BaseModelType
   use BaseExchangeModule, only: BaseExchangeType
   use BaseSolutionModule, only: BaseSolutionType, AddBaseSolutionToList
   use ListModule, only: ListType
   use ListsModule, only: basesolutionlist
-  use InputOutputModule, only: getunit
+  use InputOutputModule, only: getunit, append_processor_id
   use NumericalModelModule, only: NumericalModelType, &
                                   AddNumericalModelToList, &
                                   GetNumericalModelFromList
@@ -27,26 +29,32 @@ module NumericalSolutionModule
                                      AddNumericalExchangeToList, &
                                      GetNumericalExchangeFromList
   use SparseModule, only: sparsematrix
-  use SimVariablesModule, only: iout, isim_mode
+  use SimVariablesModule, only: iout, isim_mode, errmsg, &
+                                proc_id, nr_procs, simulation_mode
   use SimStagesModule
   use BlockParserModule, only: BlockParserType
   use IMSLinearModule
   use MatrixBaseModule
   use VectorBaseModule
   use LinearSolverBaseModule
+  use ImsLinearSettingsModule
   use LinearSolverFactory, only: create_linear_solver
-  use SparseMatrixModule
   use MatrixBaseModule
+  use ConvergenceSummaryModule
 
   implicit none
   private
 
   public :: NumericalSolutionType
   public :: GetNumericalSolutionFromList
+  public :: CastAsNumericalSolutionClass
   public :: create_numerical_solution
 
+  integer(I4B), parameter :: IMS_SOLVER = 1
+  integer(I4B), parameter :: PETSC_SOLVER = 2
+
   type, extends(BaseSolutionType) :: NumericalSolutionType
-    character(len=LENMEMPATH) :: memoryPath !< the path for storing solution variables in the memory manager
+    character(len=LENMEMPATH) :: memory_path !< the path for storing solution variables in the memory manager
     character(len=LINELENGTH) :: fname !< input file name
     character(len=16) :: solver_mode !< the type of solve: sequential, parallel, mayve block, etc.
     type(ListType), pointer :: modellist !< list of models in solution
@@ -58,10 +66,10 @@ module NumericalSolutionModule
     integer(I4B), pointer :: isymmetric => null() !< flag indicating if matrix symmetry is required
     integer(I4B), pointer :: neq => null() !< number of equations
     integer(I4B), pointer :: matrix_offset => null() !< offset of linear system when part of distributed solution
-    class(LinearSolverBaseType), pointer :: linear_solver !< the linear solver for this solution
-    class(MatrixBaseType), pointer :: system_matrix !< sparse A-matrix for the system of equations
-    class(VectorBaseType), pointer :: vec_rhs !< the right-hand side vector
-    class(VectorBaseType), pointer :: vec_x !< the dependent-variable vector
+    class(LinearSolverBaseType), pointer :: linear_solver => null() !< the linear solver for this solution
+    class(MatrixBaseType), pointer :: system_matrix => null() !< sparse A-matrix for the system of equations
+    class(VectorBaseType), pointer :: vec_rhs => null() !< the right-hand side vector
+    class(VectorBaseType), pointer :: vec_x => null() !< the dependent-variable vector
     real(DP), dimension(:), pointer, contiguous :: rhs => null() !< right-hand side vector values
     real(DP), dimension(:), pointer, contiguous :: x => null() !< dependent-variable vector values
     integer(I4B), dimension(:), pointer, contiguous :: active => null() !< active cell array
@@ -87,7 +95,7 @@ module NumericalSolutionModule
     integer(I4B), pointer :: iouttot_timestep => null() !< total nr. of outer iterations per call to sln_ca
     integer(I4B), pointer :: itertot_sim => null() !< total nr. of inner iterations for simulation
     integer(I4B), pointer :: mxiter => null() !< maximum number of Picard iterations
-    integer(I4B), pointer :: linmeth => null() !< linear acceleration method used
+    integer(I4B), pointer :: linsolver => null() !< linear solver used (IMS, PETSC, ...)
     integer(I4B), pointer :: nonmeth => null() !< under-relaxation method used
     integer(I4B), pointer :: numtrack => null() !< maximum number of backtracks
     integer(I4B), pointer :: iprims => null() !< solver print option
@@ -106,15 +114,10 @@ module NumericalSolutionModule
     integer(I4B), pointer :: nitermax => null() !< maximum number of iterations in a time step (maxiter * maxinner)
     integer(I4B), pointer :: convnmod => null() !< number of models in the solution
     integer(I4B), dimension(:), pointer, contiguous :: convmodstart => null() !< pointer to the start of each model in the convmod* arrays
-    integer(I4B), dimension(:), pointer, contiguous :: locdv => null() !< location of the maximum dependent-variable change in the solution
-    integer(I4B), dimension(:), pointer, contiguous :: locdr => null() !< location of the maximum flow change in the solution
-    integer(I4B), dimension(:), pointer, contiguous :: itinner => null() !< actual number of inner iterations in each Picard iteration
-    integer(I4B), pointer, dimension(:, :), contiguous :: convlocdv => null() !< location of the maximum dependent-variable change in each model in the solution
-    integer(I4B), pointer, dimension(:, :), contiguous :: convlocdr => null() !< location of the maximum flow change in each model in the solution
-    real(DP), dimension(:), pointer, contiguous :: dvmax => null() !< maximum dependent-variable change in the solution
-    real(DP), dimension(:), pointer, contiguous :: drmax => null() !< maximum flow change in the solution
-    real(DP), pointer, dimension(:, :), contiguous :: convdvmax => null() !< maximum dependent-variable change in each model in the solution
-    real(DP), pointer, dimension(:, :), contiguous :: convdrmax => null() !< maximum flow change in each model in the solution
+    !
+    ! -- refactoring
+    type(ConvergenceSummaryType), pointer :: cnvg_summary => null() !< details on the convergence behavior within a timestep
+    type(ImsLinearSettingsType), pointer :: linear_settings => null() !< IMS settings for linear solver
     !
     ! -- pseudo-transient continuation
     integer(I4B), pointer :: iallowptc => null() !< flag indicating if ptc applied this time step
@@ -159,8 +162,12 @@ module NumericalSolutionModule
 
     ! 'protected' (this can be overridden)
     procedure :: sln_has_converged
+    procedure :: sln_package_convergence
+    procedure :: sln_sync_newtonur_flag
+    procedure :: sln_nur_has_converged
     procedure :: sln_calc_ptc
     procedure :: sln_underrelax
+    procedure :: sln_backtracking_xupdate
 
     ! private
     procedure, private :: sln_connect
@@ -168,7 +175,6 @@ module NumericalSolutionModule
     procedure, private :: sln_ls
     procedure, private :: sln_setouter
     procedure, private :: sln_backtracking
-    procedure, private :: sln_backtracking_xupdate
     procedure, private :: sln_maxval
     procedure, private :: sln_calcdx
     procedure, private :: sln_calc_residual
@@ -222,20 +228,16 @@ subroutine create_numerical_solution(num_sol, filename, id)
     integer(I4B) :: inunit
     class(BaseSolutionType), pointer :: solbase => null()
     character(len=LENSOLUTIONNAME) :: solutionname
-    class(SparseMatrixType), pointer :: matrix_impl
     !
     ! -- Create a new solution and add it to the basesolutionlist container
     solbase => num_sol
     write (solutionname, '(a, i0)') 'SLN_', id
     !
     num_sol%name = solutionname
-    num_sol%memoryPath = create_mem_path(solutionname)
+    num_sol%memory_path = create_mem_path(solutionname)
     allocate (num_sol%modellist)
     allocate (num_sol%exchangelist)
     !
-    allocate (matrix_impl)
-    num_sol%system_matrix => matrix_impl
-    !
     call num_sol%allocate_scalars()
     !
     call AddBaseSolutionToList(basesolutionlist, solbase)
@@ -271,48 +273,48 @@ subroutine allocate_scalars(this)
     class(NumericalSolutionType) :: this
     !
     ! -- allocate scalars
-    call mem_allocate(this%id, 'ID', this%memoryPath)
-    call mem_allocate(this%iu, 'IU', this%memoryPath)
-    call mem_allocate(this%ttform, 'TTFORM', this%memoryPath)
-    call mem_allocate(this%ttsoln, 'TTSOLN', this%memoryPath)
-    call mem_allocate(this%isymmetric, 'ISYMMETRIC', this%memoryPath)
-    call mem_allocate(this%neq, 'NEQ', this%memoryPath)
-    call mem_allocate(this%matrix_offset, 'MATRIX_OFFSET', this%memoryPath)
-    call mem_allocate(this%dvclose, 'DVCLOSE', this%memoryPath)
-    call mem_allocate(this%bigchold, 'BIGCHOLD', this%memoryPath)
-    call mem_allocate(this%bigch, 'BIGCH', this%memoryPath)
-    call mem_allocate(this%relaxold, 'RELAXOLD', this%memoryPath)
-    call mem_allocate(this%res_prev, 'RES_PREV', this%memoryPath)
-    call mem_allocate(this%res_new, 'RES_NEW', this%memoryPath)
-    call mem_allocate(this%icnvg, 'ICNVG', this%memoryPath)
-    call mem_allocate(this%itertot_timestep, 'ITERTOT_TIMESTEP', this%memoryPath)
-    call mem_allocate(this%iouttot_timestep, 'IOUTTOT_TIMESTEP', this%memoryPath)
-    call mem_allocate(this%itertot_sim, 'INNERTOT_SIM', this%memoryPath)
-    call mem_allocate(this%mxiter, 'MXITER', this%memoryPath)
-    call mem_allocate(this%linmeth, 'LINMETH', this%memoryPath)
-    call mem_allocate(this%nonmeth, 'NONMETH', this%memoryPath)
-    call mem_allocate(this%iprims, 'IPRIMS', this%memoryPath)
-    call mem_allocate(this%theta, 'THETA', this%memoryPath)
-    call mem_allocate(this%akappa, 'AKAPPA', this%memoryPath)
-    call mem_allocate(this%gamma, 'GAMMA', this%memoryPath)
-    call mem_allocate(this%amomentum, 'AMOMENTUM', this%memoryPath)
-    call mem_allocate(this%breduc, 'BREDUC', this%memoryPath)
-    call mem_allocate(this%btol, 'BTOL', this%memoryPath)
-    call mem_allocate(this%res_lim, 'RES_LIM', this%memoryPath)
-    call mem_allocate(this%numtrack, 'NUMTRACK', this%memoryPath)
-    call mem_allocate(this%ibflag, 'IBFLAG', this%memoryPath)
-    call mem_allocate(this%icsvouterout, 'ICSVOUTEROUT', this%memoryPath)
-    call mem_allocate(this%icsvinnerout, 'ICSVINNEROUT', this%memoryPath)
-    call mem_allocate(this%nitermax, 'NITERMAX', this%memoryPath)
-    call mem_allocate(this%convnmod, 'CONVNMOD', this%memoryPath)
-    call mem_allocate(this%iallowptc, 'IALLOWPTC', this%memoryPath)
-    call mem_allocate(this%iptcopt, 'IPTCOPT', this%memoryPath)
-    call mem_allocate(this%iptcout, 'IPTCOUT', this%memoryPath)
-    call mem_allocate(this%l2norm0, 'L2NORM0', this%memoryPath)
-    call mem_allocate(this%ptcdel, 'PTCDEL', this%memoryPath)
-    call mem_allocate(this%ptcdel0, 'PTCDEL0', this%memoryPath)
-    call mem_allocate(this%ptcexp, 'PTCEXP', this%memoryPath)
-    call mem_allocate(this%atsfrac, 'ATSFRAC', this%memoryPath)
+    call mem_allocate(this%id, 'ID', this%memory_path)
+    call mem_allocate(this%iu, 'IU', this%memory_path)
+    call mem_allocate(this%ttform, 'TTFORM', this%memory_path)
+    call mem_allocate(this%ttsoln, 'TTSOLN', this%memory_path)
+    call mem_allocate(this%isymmetric, 'ISYMMETRIC', this%memory_path)
+    call mem_allocate(this%neq, 'NEQ', this%memory_path)
+    call mem_allocate(this%matrix_offset, 'MATRIX_OFFSET', this%memory_path)
+    call mem_allocate(this%dvclose, 'DVCLOSE', this%memory_path)
+    call mem_allocate(this%bigchold, 'BIGCHOLD', this%memory_path)
+    call mem_allocate(this%bigch, 'BIGCH', this%memory_path)
+    call mem_allocate(this%relaxold, 'RELAXOLD', this%memory_path)
+    call mem_allocate(this%res_prev, 'RES_PREV', this%memory_path)
+    call mem_allocate(this%res_new, 'RES_NEW', this%memory_path)
+    call mem_allocate(this%icnvg, 'ICNVG', this%memory_path)
+    call mem_allocate(this%itertot_timestep, 'ITERTOT_TIMESTEP', this%memory_path)
+    call mem_allocate(this%iouttot_timestep, 'IOUTTOT_TIMESTEP', this%memory_path)
+    call mem_allocate(this%itertot_sim, 'INNERTOT_SIM', this%memory_path)
+    call mem_allocate(this%mxiter, 'MXITER', this%memory_path)
+    call mem_allocate(this%linsolver, 'LINSOLVER', this%memory_path)
+    call mem_allocate(this%nonmeth, 'NONMETH', this%memory_path)
+    call mem_allocate(this%iprims, 'IPRIMS', this%memory_path)
+    call mem_allocate(this%theta, 'THETA', this%memory_path)
+    call mem_allocate(this%akappa, 'AKAPPA', this%memory_path)
+    call mem_allocate(this%gamma, 'GAMMA', this%memory_path)
+    call mem_allocate(this%amomentum, 'AMOMENTUM', this%memory_path)
+    call mem_allocate(this%breduc, 'BREDUC', this%memory_path)
+    call mem_allocate(this%btol, 'BTOL', this%memory_path)
+    call mem_allocate(this%res_lim, 'RES_LIM', this%memory_path)
+    call mem_allocate(this%numtrack, 'NUMTRACK', this%memory_path)
+    call mem_allocate(this%ibflag, 'IBFLAG', this%memory_path)
+    call mem_allocate(this%icsvouterout, 'ICSVOUTEROUT', this%memory_path)
+    call mem_allocate(this%icsvinnerout, 'ICSVINNEROUT', this%memory_path)
+    call mem_allocate(this%nitermax, 'NITERMAX', this%memory_path)
+    call mem_allocate(this%convnmod, 'CONVNMOD', this%memory_path)
+    call mem_allocate(this%iallowptc, 'IALLOWPTC', this%memory_path)
+    call mem_allocate(this%iptcopt, 'IPTCOPT', this%memory_path)
+    call mem_allocate(this%iptcout, 'IPTCOUT', this%memory_path)
+    call mem_allocate(this%l2norm0, 'L2NORM0', this%memory_path)
+    call mem_allocate(this%ptcdel, 'PTCDEL', this%memory_path)
+    call mem_allocate(this%ptcdel0, 'PTCDEL0', this%memory_path)
+    call mem_allocate(this%ptcexp, 'PTCEXP', this%memory_path)
+    call mem_allocate(this%atsfrac, 'ATSFRAC', this%memory_path)
     !
     ! -- initialize scalars
     this%isymmetric = 0
@@ -331,7 +333,7 @@ subroutine allocate_scalars(this)
     this%iouttot_timestep = 0
     this%itertot_sim = 0
     this%mxiter = 0
-    this%linmeth = 1
+    this%linsolver = IMS_SOLVER
     this%nonmeth = 0
     this%iprims = 0
     this%theta = DONE
@@ -379,29 +381,16 @@ subroutine allocate_arrays(this)
     this%convnmod = this%modellist%Count()
     !
     ! -- allocate arrays
-    call mem_allocate(this%active, this%neq, 'IACTIVE', this%memoryPath)
-    call mem_allocate(this%xtemp, this%neq, 'XTEMP', this%memoryPath)
-    call mem_allocate(this%dxold, this%neq, 'DXOLD', this%memoryPath)
-    call mem_allocate(this%hncg, 0, 'HNCG', this%memoryPath)
-    call mem_allocate(this%lrch, 3, 0, 'LRCH', this%memoryPath)
-    call mem_allocate(this%wsave, 0, 'WSAVE', this%memoryPath)
-    call mem_allocate(this%hchold, 0, 'HCHOLD', this%memoryPath)
-    call mem_allocate(this%deold, 0, 'DEOLD', this%memoryPath)
+    call mem_allocate(this%active, this%neq, 'IACTIVE', this%memory_path)
+    call mem_allocate(this%xtemp, this%neq, 'XTEMP', this%memory_path)
+    call mem_allocate(this%dxold, this%neq, 'DXOLD', this%memory_path)
+    call mem_allocate(this%hncg, 0, 'HNCG', this%memory_path)
+    call mem_allocate(this%lrch, 3, 0, 'LRCH', this%memory_path)
+    call mem_allocate(this%wsave, 0, 'WSAVE', this%memory_path)
+    call mem_allocate(this%hchold, 0, 'HCHOLD', this%memory_path)
+    call mem_allocate(this%deold, 0, 'DEOLD', this%memory_path)
     call mem_allocate(this%convmodstart, this%convnmod + 1, 'CONVMODSTART', &
-                      this%memoryPath)
-    call mem_allocate(this%locdv, this%convnmod, 'LOCDV', this%memoryPath)
-    call mem_allocate(this%locdr, this%convnmod, 'LOCDR', this%memoryPath)
-    call mem_allocate(this%itinner, 0, 'ITINNER', this%memoryPath)
-    call mem_allocate(this%convlocdv, this%convnmod, 0, 'CONVLOCDV', &
-                      this%memoryPath)
-    call mem_allocate(this%convlocdr, this%convnmod, 0, 'CONVLOCDR', &
-                      this%memoryPath)
-    call mem_allocate(this%dvmax, this%convnmod, 'DVMAX', this%memoryPath)
-    call mem_allocate(this%drmax, this%convnmod, 'DRMAX', this%memoryPath)
-    call mem_allocate(this%convdvmax, this%convnmod, 0, 'CONVDVMAX', &
-                      this%memoryPath)
-    call mem_allocate(this%convdrmax, this%convnmod, 0, 'CONVDRMAX', &
-                      this%memoryPath)
+                      this%memory_path)
     !
     ! -- initialize allocated arrays
     do i = 1, this%neq
@@ -409,12 +398,6 @@ subroutine allocate_arrays(this)
       this%dxold(i) = DZERO
       this%active(i) = 1 !default is active
     end do
-    do i = 1, this%convnmod
-      this%locdv(i) = 0
-      this%locdr(i) = 0
-      this%dvmax(i) = DZERO
-      this%drmax(i) = DZERO
-    end do
     !
     ! -- initialize convmodstart
     ieq = 1
@@ -464,13 +447,18 @@ subroutine sln_df(this)
     else
       this%solver_mode = 'IMS'
     end if
+    !
+    ! -- allocate settings structure
+    allocate (this%linear_settings)
+    !
     ! -- create linear system matrix and compatible vectors
     this%linear_solver => create_linear_solver(this%solver_mode)
     this%system_matrix => this%linear_solver%create_matrix()
-    this%vec_x => this%system_matrix%create_vec_mm(this%neq, 'X', this%memoryPath)
+    this%vec_x => this%system_matrix%create_vec_mm(this%neq, 'X', &
+                                                   this%memory_path)
     this%x => this%vec_x%get_array()
     this%vec_rhs => this%system_matrix%create_vec_mm(this%neq, 'RHS', &
-                                                     this%memoryPath)
+                                                     this%memory_path)
     this%rhs => this%vec_rhs%get_array()
     !
     call this%vec_rhs%get_ownership_range(irow_start, irow_end)
@@ -488,6 +476,11 @@ subroutine sln_df(this)
     ! -- Allocate and initialize solution arrays
     call this%allocate_arrays()
     !
+    ! -- Create convergence summary report
+    allocate (this%cnvg_summary)
+    call this%cnvg_summary%init(this%modellist%Count(), this%convmodstart, &
+                                this%memory_path)
+    !
     ! -- Go through each model and point x, ibound, and rhs to solution
     do i = 1, this%modellist%Count()
       mp => GetNumericalModelFromList(this%modellist, i)
@@ -528,17 +521,14 @@ subroutine sln_ar(this)
     ! -- local variables
     class(NumericalModelType), pointer :: mp => null()
     class(NumericalExchangeType), pointer :: cp => null()
-    character(len=linelength) :: errmsg
     character(len=linelength) :: warnmsg
     character(len=linelength) :: keyword
     character(len=linelength) :: fname
     character(len=linelength) :: msg
     integer(I4B) :: i
-    integer(I4B) :: im
     integer(I4B) :: ifdparam, mxvl, npp
-    integer(I4B) :: ims_lin_type
     integer(I4B) :: ierr
-    logical :: isfound, endOfBlock
+    logical(LGP) :: isfound, endOfBlock
     integer(I4B) :: ival
     real(DP) :: rval
     character(len=*), parameter :: fmtcsvout = &
@@ -607,6 +597,9 @@ subroutine sln_ar(this)
           call this%parser%GetStringCaps(keyword)
           if (keyword == 'FILEOUT') then
             call this%parser%GetString(fname)
+            if (nr_procs > 1) then
+              call append_processor_id(fname, proc_id)
+            end if
             this%icsvouterout = getunit()
             call openfile(this%icsvouterout, iout, fname, 'CSV_OUTER_OUTPUT', &
                           filstat_opt='REPLACE')
@@ -620,6 +613,9 @@ subroutine sln_ar(this)
           call this%parser%GetStringCaps(keyword)
           if (keyword == 'FILEOUT') then
             call this%parser%GetString(fname)
+            if (nr_procs > 1) then
+              call append_processor_id(fname, proc_id)
+            end if
             this%icsvinnerout = getunit()
             call openfile(this%icsvinnerout, iout, fname, 'CSV_INNER_OUTPUT', &
                           filstat_opt='REPLACE')
@@ -792,16 +788,16 @@ subroutine sln_ar(this)
           this%nonmeth = ival
         case ('LINEAR_SOLVER')
           call this%parser%GetStringCaps(keyword)
-          ival = 1
+          ival = IMS_SOLVER
           if (keyword .eq. 'DEFAULT' .or. &
               keyword .eq. 'LINEAR') then
-            ival = 1
+            ival = IMS_SOLVER
           else
             write (errmsg, '(3a)') &
               'Unknown LINEAR_SOLVER specified (', trim(keyword), ').'
             call store_error(errmsg)
           end if
-          this%linmeth = ival
+          this%linsolver = ival
         case ('UNDER_RELAXATION_THETA')
           this%theta = this%parser%GetDouble()
         case ('UNDER_RELAXATION_KAPPA')
@@ -892,35 +888,40 @@ subroutine sln_ar(this)
     end if
 
     if (this%solver_mode == 'PETSC') then
-      this%linmeth = 2
+      this%linsolver = PETSC_SOLVER
     end if
 
+    ! configure linear settings
+    call this%linear_settings%init(this%memory_path)
+    call this%linear_settings%preset_config(ifdparam)
+    call this%linear_settings%read_from_file(this%parser, iout)
+    !
+    if (this%linear_settings%ilinmeth == CG_METHOD) then
+      this%isymmetric = 1
+    end if
     !
     ! -- call secondary subroutine to initialize and read linear
     !    solver parameters IMSLINEAR solver
-    if (this%linmeth == 1) then
+    if (this%solver_mode == "IMS") then
       allocate (this%imslinear)
       WRITE (IOUT, *) '***IMS LINEAR SOLVER WILL BE USED***'
-      call this%imslinear%imslinear_allocate(this%name, this%parser, IOUT, &
-                                             this%iprims, this%mxiter, &
-                                             ifdparam, ims_lin_type, &
-                                             this%neq, this%system_matrix, &
-                                             this%rhs, this%x, this%nitermax)
-      if (ims_lin_type .eq. 1) then
-        this%isymmetric = 1
-      end if
+      call this%imslinear%imslinear_allocate(this%name, IOUT, this%iprims, &
+                                             this%mxiter, this%neq, &
+                                             this%system_matrix, this%rhs, &
+                                             this%x, this%linear_settings)
+      !
+      ! -- petsc linear solver flag
+    else if (this%solver_mode == "PETSC") then
+      call this%linear_solver%initialize(this%system_matrix, &
+                                         this%linear_settings, &
+                                         this%cnvg_summary)
       !
       ! -- incorrect linear solver flag
-    else if (this%linmeth == 2) then
-      call this%linear_solver%initialize(this%system_matrix)
-      this%nitermax = this%linear_solver%nitermax
-      this%isymmetric = 0
-    ELSE
-      WRITE (errmsg, '(a)') &
+    else
+      write (errmsg, '(a)') &
         'Incorrect value for linear solution method specified.'
       call store_error(errmsg)
-    END IF
-
+    end if
     !
     ! -- write message about matrix symmetry
     if (this%isymmetric == 1) then
@@ -957,7 +958,7 @@ subroutine sln_ar(this)
     !
     ! -- non-linear solver data
     WRITE (IOUT, 9002) this%dvclose, this%mxiter, &
-      this%iprims, this%nonmeth, this%linmeth
+      this%iprims, this%nonmeth, this%linsolver
     !
     ! -- standard outer iteration formats
 9002 FORMAT(1X, 'OUTER ITERATION CONVERGENCE CRITERION    (DVCLOSE) = ', E15.6, &
@@ -993,8 +994,10 @@ subroutine sln_ar(this)
            /1X, 'BACKTRACKING RESIDUAL LIMIT              (RES_LIM) = ', E15.6)
     !
     ! -- linear solver data
-    if (this%linmeth == 1) then
+    if (this%linsolver == IMS_SOLVER) then
       call this%imslinear%imslinear_summary(this%mxiter)
+    else
+      call this%linear_solver%print_summary()
     end if
 
     ! -- write summary of solver error messages
@@ -1023,33 +1026,16 @@ subroutine sln_ar(this)
 
     ! allocate space for saving solver convergence history
     if (this%iprims == 2 .or. this%icsvinnerout > 0) then
-      this%nitermax = this%nitermax * this%mxiter
+      this%nitermax = this%linear_settings%iter1 * this%mxiter
     else
       this%nitermax = 1
     end if
 
     allocate (this%caccel(this%nitermax))
 
-    im = this%convnmod
-    call mem_reallocate(this%itinner, this%nitermax, 'ITINNER', &
-                        trim(this%name))
-    call mem_reallocate(this%convlocdv, im, this%nitermax, 'CONVLOCDV', &
-                        trim(this%name))
-    call mem_reallocate(this%convlocdr, im, this%nitermax, 'CONVLOCDR', &
-                        trim(this%name))
-    call mem_reallocate(this%convdvmax, im, this%nitermax, 'CONVDVMAX', &
-                        trim(this%name))
-    call mem_reallocate(this%convdrmax, im, this%nitermax, 'CONVDRMAX', &
-                        trim(this%name))
-    do i = 1, this%nitermax
-      this%itinner(i) = 0
-      do im = 1, this%convnmod
-        this%convlocdv(im, i) = 0
-        this%convlocdr(im, i) = 0
-        this%convdvmax(im, i) = DZERO
-        this%convdrmax(im, i) = DZERO
-      end do
-    end do
+    !
+    ! -- resize convergence report
+    call this%cnvg_summary%reinit(this%nitermax)
     !
     ! -- check for numerical solution errors
     ierr = count_errors()
@@ -1102,7 +1088,7 @@ subroutine sln_calculate_delt(this)
       end if
       !
       ! -- submit stable dt for upcoming step
-      call ats_submit_delt(kstp, kper, delt_temp, this%memoryPath, idir=idir)
+      call ats_submit_delt(kstp, kper, delt_temp, this%memory_path, idir=idir)
     end if
     !
     return
@@ -1187,7 +1173,7 @@ subroutine sln_da(this)
     class(NumericalSolutionType) :: this !< NumericalSolutionType instance
     !
     ! -- IMSLinearModule
-    if (this%linmeth == 1) then
+    if (this%linsolver == IMS_SOLVER) then
       call this%imslinear%imslinear_da()
       deallocate (this%imslinear)
     end if
@@ -1233,15 +1219,18 @@ subroutine sln_da(this)
     call mem_deallocate(this%hchold)
     call mem_deallocate(this%deold)
     call mem_deallocate(this%convmodstart)
-    call mem_deallocate(this%locdv)
-    call mem_deallocate(this%locdr)
-    call mem_deallocate(this%itinner)
-    call mem_deallocate(this%convlocdv)
-    call mem_deallocate(this%convlocdr)
-    call mem_deallocate(this%dvmax)
-    call mem_deallocate(this%drmax)
-    call mem_deallocate(this%convdvmax)
-    call mem_deallocate(this%convdrmax)
+    !
+    ! -- convergence report
+    call this%cnvg_summary%destroy()
+    deallocate (this%cnvg_summary)
+    !
+    ! -- linear solver
+    call this%linear_solver%destroy()
+    deallocate (this%linear_solver)
+    !
+    ! -- linear solver settings
+    call this%linear_settings%destroy()
+    deallocate (this%linear_settings)
     !
     ! -- Scalars
     call mem_deallocate(this%id)
@@ -1262,7 +1251,7 @@ subroutine sln_da(this)
     call mem_deallocate(this%iouttot_timestep)
     call mem_deallocate(this%itertot_sim)
     call mem_deallocate(this%mxiter)
-    call mem_deallocate(this%linmeth)
+    call mem_deallocate(this%linsolver)
     call mem_deallocate(this%nonmeth)
     call mem_deallocate(this%iprims)
     call mem_deallocate(this%theta)
@@ -1371,13 +1360,18 @@ subroutine writeCSVHeader(this)
         'solution_inner_dvmax_node'
       write (this%icsvinnerout, '(*(G0,:,","))', advance='NO') &
         '', 'solution_inner_drmax', 'solution_inner_drmax_model', &
-        'solution_inner_drmax_node', 'solution_inner_alpha'
-      if (this%imslinear%ilinmeth == 2) then
+        'solution_inner_drmax_node'
+      ! solver items specific to ims solver
+      if (this%linsolver == IMS_SOLVER) then
         write (this%icsvinnerout, '(*(G0,:,","))', advance='NO') &
-          '', 'solution_inner_omega'
+          '', 'solution_inner_alpha'
+        if (this%imslinear%ilinmeth == 2) then
+          write (this%icsvinnerout, '(*(G0,:,","))', advance='NO') &
+            '', 'solution_inner_omega'
+        end if
       end if
-      ! -- check for more than one model
-      if (this%convnmod > 1) then
+      ! -- check for more than one model - ims only
+      if (this%linsolver == IMS_SOLVER .and. this%convnmod > 1) then
         do im = 1, this%modellist%Count()
           mp => GetNumericalModelFromList(this%modellist, im)
           write (this%icsvinnerout, '(*(G0,:,","))', advance='NO') &
@@ -1499,7 +1493,6 @@ subroutine solve(this, kiter)
     class(NumericalExchangeType), pointer :: cp => null()
     character(len=LINELENGTH) :: title
     character(len=LINELENGTH) :: tag
-    character(len=LINELENGTH) :: line
     character(len=LENPAKLOC) :: cmod
     character(len=LENPAKLOC) :: cpak
     character(len=LENPAKLOC) :: cpakout
@@ -1525,7 +1518,7 @@ subroutine solve(this, kiter)
     integer(I4B) :: ipos0
     integer(I4B) :: ipos1
     real(DP) :: dxmax_nur
-    real(DP) :: dxmax
+    real(DP) :: dxold_max
     real(DP) :: ptcf
     real(DP) :: ttform
     real(DP) :: ttsoln
@@ -1549,7 +1542,7 @@ subroutine solve(this, kiter)
         end if
         !
         ! -- initialize table and define columns
-        title = trim(this%memoryPath)//' OUTER ITERATION SUMMARY'
+        title = trim(this%memory_path)//' OUTER ITERATION SUMMARY'
         call table_cr(this%outertab, this%name, title)
         call this%outertab%table_df(ntabrows, ntabcols, iout, &
                                     finalize=.FALSE.)
@@ -1619,7 +1612,7 @@ subroutine solve(this, kiter)
       WRITE (99, *) 'MATRIX SOLUTION FOLLOWS'
       WRITE (99, '(10(I8,G15.4))') (n, this%x(N), N=1, this%NEQ)
       close (99)
-      call stop_with_error()
+      call pstop()
     end if
     !-------------------------------------------------------
     !
@@ -1689,47 +1682,41 @@ subroutine solve(this, kiter)
       end if
     end do
     !
-    ! -- evaluate package convergence
-    if (abs(dpak) > this%dvclose) then
-      this%icnvg = 0
-      ! -- write message to stdout
-      if (iend /= 0) then
-        write (line, '(3a)') &
-          'PACKAGE (', trim(cpakout), ') CAUSED CONVERGENCE FAILURE'
-        call sim_message(line)
-      end if
-    end if
-    !
-    ! -- write maximum change in package convergence check
-    if (this%iprims > 0) then
-      cval = 'Package'
-      if (this%icnvg /= 1) then
-        cmsg = ' '
-      else
-        cmsg = '*'
-      end if
-      if (len_trim(cpakout) > 0) then
-        !
-        ! -- add data to outertab
-        call this%outertab%add_term(cval)
-        call this%outertab%add_term(kiter)
-        call this%outertab%add_term(' ')
-        if (this%numtrack > 0) then
-          call this%outertab%add_term(' ')
-          call this%outertab%add_term(' ')
-          call this%outertab%add_term(' ')
+    ! -- evaluate package convergence - only done if convergence is achieved
+    if (this%icnvg == 1) then
+      this%icnvg = this%sln_package_convergence(dpak, cpakout, iend)
+      !
+      ! -- write maximum change in package convergence check
+      if (this%iprims > 0) then
+        cval = 'Package'
+        if (this%icnvg /= 1) then
+          cmsg = ' '
+        else
+          cmsg = '*'
+        end if
+        if (len_trim(cpakout) > 0) then
+          !
+          ! -- add data to outertab
+          call this%outertab%add_term(cval)
+          call this%outertab%add_term(kiter)
           call this%outertab%add_term(' ')
+          if (this%numtrack > 0) then
+            call this%outertab%add_term(' ')
+            call this%outertab%add_term(' ')
+            call this%outertab%add_term(' ')
+            call this%outertab%add_term(' ')
+          end if
+          call this%outertab%add_term(dpak)
+          call this%outertab%add_term(cmsg)
+          call this%outertab%add_term(cpakout)
         end if
-        call this%outertab%add_term(dpak)
-        call this%outertab%add_term(cmsg)
-        call this%outertab%add_term(cpakout)
       end if
     end if
     !
     ! -- under-relaxation - only done if convergence not achieved
     if (this%icnvg /= 1) then
       if (this%nonmeth > 0) then
-        call this%sln_underrelax(kiter, this%hncg(kiter), this%neq, & ! TODO_MJR: this is not equiv. serial/parallel
+        call this%sln_underrelax(kiter, this%hncg(kiter), this%neq, &
                                  this%active, this%x, this%xtemp)
       else
         call this%sln_calcdx(this%neq, this%active, &
@@ -1748,17 +1735,20 @@ subroutine solve(this, kiter)
                           this%dxold(i0:i1), inewtonur, dxmax_nur, locmax_nur)
       end do
       !
+      ! -- synchronize Newton Under-relaxation flag
+      inewtonur = this%sln_sync_newtonur_flag(inewtonur)
+      !
       ! -- check for convergence if newton under-relaxation applied
       if (inewtonur /= 0) then
         !
         ! -- calculate maximum change in heads in cells that have
         !    not been adjusted by newton under-relxation
-        call this%sln_maxval(this%neq, this%dxold, dxmax)
+        call this%sln_maxval(this%neq, this%dxold, dxold_max)
         !
         ! -- evaluate convergence
-        if (abs(dxmax) <= this%dvclose .and. &
-            abs(this%hncg(kiter)) <= this%dvclose .and. &
-            abs(dpak) <= this%dvclose) then
+        if (this%sln_nur_has_converged(dxold_max, this%hncg(kiter))) then
+          !
+          ! -- converged
           this%icnvg = 1
           !
           ! -- reset outer dependent-variable change and location for output
@@ -1920,7 +1910,6 @@ subroutine sln_buildsystem(this, kiter, inewton)
     class(NumericalSolutionType) :: this
     integer(I4B), intent(in) :: kiter
     integer(I4B), intent(in) :: inewton
-
     ! local
     integer(I4B) :: im, ic
     class(NumericalModelType), pointer :: mp
@@ -1929,6 +1918,12 @@ subroutine sln_buildsystem(this, kiter, inewton)
     ! -- Set amat and rhs to zero
     call this%sln_reset()
 
+    ! reset models
+    do im = 1, this%modellist%Count()
+      mp => GetNumericalModelFromList(this%modellist, im)
+      call mp%model_reset()
+    end do
+
     ! synchronize for CF
     call this%synchronize(STG_BFR_EXG_CF, this%synchronize_ctx)
 
@@ -1983,7 +1978,7 @@ subroutine convergence_summary(this, iu, im, itertot_timestep)
     character(len=LENPAKLOC) :: strr
     integer(I4B) :: ntabrows
     integer(I4B) :: ntabcols
-    integer(I4B) :: i
+    integer(I4B) :: iinner
     integer(I4B) :: i0
     integer(I4B) :: iouter
     integer(I4B) :: j
@@ -2009,7 +2004,7 @@ subroutine convergence_summary(this, iu, im, itertot_timestep)
       ntabcols = 7
       !
       ! -- initialize table and define columns
-      title = trim(this%memoryPath)//' INNER ITERATION SUMMARY'
+      title = trim(this%memory_path)//' INNER ITERATION SUMMARY'
       call table_cr(this%innertab, this%name, title)
       call this%innertab%table_df(ntabrows, ntabcols, iu)
       tag = 'TOTAL ITERATION'
@@ -2036,28 +2031,28 @@ subroutine convergence_summary(this, iu, im, itertot_timestep)
     ! -- write the inner iteration summary to unit iu
     i0 = 0
     do k = 1, itertot_timestep
-      i = this%itinner(k)
-      if (i <= i0) then
+      iinner = this%cnvg_summary%itinner(k)
+      if (iinner <= i0) then
         iouter = iouter + 1
       end if
       if (im > this%convnmod) then
         dv = DZERO
         dr = DZERO
         do j = 1, this%convnmod
-          if (ABS(this%convdvmax(j, k)) > ABS(dv)) then
-            locdv = this%convlocdv(j, k)
-            dv = this%convdvmax(j, k)
+          if (ABS(this%cnvg_summary%convdvmax(j, k)) > ABS(dv)) then
+            locdv = this%cnvg_summary%convlocdv(j, k)
+            dv = this%cnvg_summary%convdvmax(j, k)
           end if
-          if (ABS(this%convdrmax(j, k)) > ABS(dr)) then
-            locdr = this%convlocdr(j, k)
-            dr = this%convdrmax(j, k)
+          if (ABS(this%cnvg_summary%convdrmax(j, k)) > ABS(dr)) then
+            locdr = this%cnvg_summary%convlocdr(j, k)
+            dr = this%cnvg_summary%convdrmax(j, k)
           end if
         end do
       else
-        locdv = this%convlocdv(im, k)
-        locdr = this%convlocdr(im, k)
-        dv = this%convdvmax(im, k)
-        dr = this%convdrmax(im, k)
+        locdv = this%cnvg_summary%convlocdv(im, k)
+        locdr = this%cnvg_summary%convlocdr(im, k)
+        dv = this%cnvg_summary%convdvmax(im, k)
+        dr = this%cnvg_summary%convdrmax(im, k)
       end if
       call this%sln_get_loc(locdv, strh)
       call this%sln_get_loc(locdr, strr)
@@ -2065,14 +2060,14 @@ subroutine convergence_summary(this, iu, im, itertot_timestep)
       ! -- add data to innertab
       call this%innertab%add_term(k)
       call this%innertab%add_term(iouter)
-      call this%innertab%add_term(i)
+      call this%innertab%add_term(iinner)
       call this%innertab%add_term(dv)
       call this%innertab%add_term(adjustr(trim(strh)))
       call this%innertab%add_term(dr)
       call this%innertab%add_term(adjustr(trim(strr)))
       !
       ! -- update i0
-      i0 = i
+      i0 = iinner
     end do
     !
     ! -- return
@@ -2124,13 +2119,13 @@ subroutine csv_convergence_summary(this, iu, totim, kper, kstp, kouter, &
       dv = DZERO
       dr = DZERO
       do j = 1, this%convnmod
-        if (ABS(this%convdvmax(j, kpos)) > ABS(dv)) then
-          locdv = this%convlocdv(j, kpos)
-          dv = this%convdvmax(j, kpos)
+        if (ABS(this%cnvg_summary%convdvmax(j, kpos)) > ABS(dv)) then
+          locdv = this%cnvg_summary%convlocdv(j, kpos)
+          dv = this%cnvg_summary%convdvmax(j, kpos)
         end if
-        if (ABS(this%convdrmax(j, kpos)) > ABS(dr)) then
-          locdr = this%convlocdr(j, kpos)
-          dr = this%convdrmax(j, kpos)
+        if (ABS(this%cnvg_summary%convdrmax(j, kpos)) > ABS(dr)) then
+          locdr = this%cnvg_summary%convlocdr(j, kpos)
+          dr = this%cnvg_summary%convdrmax(j, kpos)
         end if
       end do
       !
@@ -2142,17 +2137,19 @@ subroutine csv_convergence_summary(this, iu, totim, kper, kstp, kouter, &
       call this%sln_get_nodeu(locdr, im, nodeu)
       write (iu, '(*(G0,:,","))', advance='NO') '', dr, im, nodeu
       !
-      ! -- write acceleration parameters
-      write (iu, '(*(G0,:,","))', advance='NO') &
-        '', trim(adjustl(this%caccel(kpos)))
+      ! -- write ims acceleration parameters
+      if (this%linsolver == IMS_SOLVER) then
+        write (iu, '(*(G0,:,","))', advance='NO') &
+          '', trim(adjustl(this%caccel(kpos)))
+      end if
       !
-      ! -- write information for each model
-      if (this%convnmod > 1) then
-        do j = 1, this%convnmod
-          locdv = this%convlocdv(j, kpos)
-          dv = this%convdvmax(j, kpos)
-          locdr = this%convlocdr(j, kpos)
-          dr = this%convdrmax(j, kpos)
+      ! -- write information for each model - ims only
+      if (this%linsolver == IMS_SOLVER .and. this%convnmod > 1) then
+        do j = 1, this%cnvg_summary%convnmod
+          locdv = this%cnvg_summary%convlocdv(j, kpos)
+          dv = this%cnvg_summary%convdvmax(j, kpos)
+          locdr = this%cnvg_summary%convlocdr(j, kpos)
+          dr = this%cnvg_summary%convdrmax(j, kpos)
           !
           ! -- get model number and user node number for dv
           call this%sln_get_nodeu(locdv, im, nodeu)
@@ -2185,6 +2182,7 @@ end subroutine csv_convergence_summary
   !!
   !<
   subroutine save(this, filename)
+    use SparseMatrixModule
     ! -- modules
     use InputOutputModule, only: getunit
     ! -- dummy variables
@@ -2379,9 +2377,9 @@ subroutine sln_ls(this, kiter, kstp, kper, in_iter, iptc, ptcf)
     integer(I4B), intent(inout) :: iptc
     real(DP), intent(in) :: ptcf
     ! -- local variables
-    logical :: lsame
+    logical(LGP) :: lsame
     integer(I4B) :: ieq
-    integer(I4B) :: irow
+    integer(I4B) :: irow_glo
     integer(I4B) :: itestmat
     integer(I4B) :: ipos
     integer(I4B) :: icol_s
@@ -2402,7 +2400,7 @@ subroutine sln_ls(this, kiter, kstp, kper, in_iter, iptc, ptcf)
     do ieq = 1, this%neq
       !
       ! -- get (global) cell id
-      irow = ieq + this%matrix_offset
+      irow_glo = ieq + this%matrix_offset
       !
       ! -- store x in temporary location
       this%xtemp(ieq) = this%x(ieq)
@@ -2411,35 +2409,33 @@ subroutine sln_ls(this, kiter, kstp, kper, in_iter, iptc, ptcf)
       ! -- adjust small diagonal coefficient in an active cell
       if (this%active(ieq) > 0) then
         diagval = -DONE
-        adiag = abs(this%system_matrix%get_diag_value(irow))
+        adiag = abs(this%system_matrix%get_diag_value(irow_glo))
         if (adiag < DEM15) then
-          call this%system_matrix%set_diag_value(irow, diagval)
+          call this%system_matrix%set_diag_value(irow_glo, diagval)
           this%rhs(ieq) = this%rhs(ieq) + diagval * this%x(ieq)
         end if
         ! -- Dirichlet boundary or no-flow cell
       else
-        call this%system_matrix%set_diag_value(irow, DONE)
-        call this%system_matrix%zero_row_offdiag(irow)
+        call this%system_matrix%set_diag_value(irow_glo, DONE)
+        call this%system_matrix%zero_row_offdiag(irow_glo)
         this%rhs(ieq) = this%x(ieq)
       end if
     end do
     !
     ! -- complete adjustments for Dirichlet boundaries for a symmetric matrix
-    if (this%isymmetric == 1) then
+    ! -- TODO_MJR: add this for PETSc/parallel
+    if (this%isymmetric == 1 .and. simulation_mode == "SEQUENTIAL") then
       do ieq = 1, this%neq
-        !
-        ! -- get (global) row number
-        irow = ieq + this%matrix_offset
         if (this%active(ieq) > 0) then
-          icol_s = this%system_matrix%get_first_col_pos(irow)
-          icol_e = this%system_matrix%get_last_col_pos(irow)
+          icol_s = this%system_matrix%get_first_col_pos(ieq)
+          icol_e = this%system_matrix%get_last_col_pos(ieq)
           do ipos = icol_s, icol_e
             jcol = this%system_matrix%get_column(ipos)
-            if (jcol == irow) cycle
-            if (this%active(jcol - this%matrix_offset) < 0) then
+            if (jcol == ieq) cycle
+            if (this%active(jcol) < 0) then
               this%rhs(ieq) = this%rhs(ieq) - &
                               (this%system_matrix%get_value_pos(ipos) * &
-                               this%x(jcol - this%matrix_offset))
+                               this%x(jcol))
               call this%system_matrix%set_value_pos(ipos, DZERO)
             end if
 
@@ -2480,7 +2476,7 @@ subroutine sln_ls(this, kiter, kstp, kper, in_iter, iptc, ptcf)
           end if
         end if
       else
-        lsame = is_same(l2norm, this%l2norm0)
+        lsame = is_close(l2norm, this%l2norm0)
         if (lsame) then
           iptc = 0
         end if
@@ -2526,11 +2522,11 @@ subroutine sln_ls(this, kiter, kstp, kper, in_iter, iptc, ptcf)
       end if
       bnorm = DZERO
       do ieq = 1, this%neq
-        irow = ieq + this%matrix_offset
+        irow_glo = ieq + this%matrix_offset
         if (this%active(ieq) > 0) then
-          diagval = abs(this%system_matrix%get_diag_value(irow))
+          diagval = abs(this%system_matrix%get_diag_value(irow_glo))
           bnorm = bnorm + this%rhs(ieq) * this%rhs(ieq)
-          call this%system_matrix%add_diag_value(irow, -ptcval)
+          call this%system_matrix%add_diag_value(irow_glo, -ptcval)
           this%rhs(ieq) = this%rhs(ieq) - ptcval * this%x(ieq)
         end if
       end do
@@ -2555,11 +2551,11 @@ subroutine sln_ls(this, kiter, kstp, kper, in_iter, iptc, ptcf)
       open (itestmat, file=trim(adjustl(fname)))
       write (itestmat, *) 'NODE, RHS, AMAT FOLLOW'
       do ieq = 1, this%neq
-        irow = ieq + this%matrix_offset
-        icol_s = this%system_matrix%get_first_col_pos(irow)
-        icol_e = this%system_matrix%get_last_col_pos(irow)
+        irow_glo = ieq + this%matrix_offset
+        icol_s = this%system_matrix%get_first_col_pos(irow_glo)
+        icol_e = this%system_matrix%get_last_col_pos(irow_glo)
         write (itestmat, '(*(G0,:,","))') &
-          irow, &
+          irow_glo, &
           this%rhs(ieq), &
           (this%system_matrix%get_column(ipos), ipos=icol_s, icol_e), &
           (this%system_matrix%get_value_pos(ipos), ipos=icol_s, icol_e)
@@ -2572,17 +2568,14 @@ subroutine sln_ls(this, kiter, kstp, kper, in_iter, iptc, ptcf)
     ! -- call appropriate linear solver
     !
     ! -- ims linear solver - linmeth option 1
-    if (this%linmeth == 1) then
+    if (this%linsolver == IMS_SOLVER) then
       call this%imslinear%imslinear_apply(this%icnvg, kstp, kiter, in_iter, &
-                                          this%nitermax, &
-                                          this%convnmod, this%convmodstart, &
-                                          this%locdv, this%locdr, &
-                                          this%caccel, this%itinner, &
-                                          this%convlocdv, this%convlocdr, &
-                                          this%dvmax, this%drmax, &
-                                          this%convdvmax, this%convdrmax)
-    else if (this%linmeth == 2) then
-      call this%linear_solver%solve(kiter, this%vec_rhs, this%vec_x)
+                                          this%nitermax, this%convnmod, &
+                                          this%convmodstart, this%caccel, &
+                                          this%cnvg_summary)
+    else if (this%linsolver == PETSC_SOLVER) then
+      call this%linear_solver%solve(kiter, this%vec_rhs, &
+                                    this%vec_x, this%cnvg_summary)
       in_iter = this%linear_solver%iteration_number
       this%icnvg = this%linear_solver%is_converged
     end if
@@ -3138,6 +3131,59 @@ function sln_has_converged(this, max_dvc) result(has_converged)
 
   end function sln_has_converged
 
+  !> @brief Check package convergence
+  !<
+  function sln_package_convergence(this, dpak, cpakout, iend) result(ivalue)
+    ! dummy
+    class(NumericalSolutionType) :: this !< NumericalSolutionType instance
+    real(DP), intent(in) :: dpak !< Newton Under-relaxation flag
+    character(len=LENPAKLOC), intent(in) :: cpakout !< string with package that caused failure
+    integer(I4B), intent(in) :: iend !< flag indicating if last inner iteration (iend=1)
+    ! local
+    integer(I4B) :: ivalue
+    ivalue = 1
+    if (abs(dpak) > this%dvclose) then
+      ivalue = 0
+      ! -- write message to stdout
+      if (iend /= 0) then
+        write (errmsg, '(3a)') &
+          'PACKAGE (', trim(cpakout), ') CAUSED CONVERGENCE FAILURE'
+        call write_message(errmsg)
+      end if
+    end if
+
+  end function sln_package_convergence
+
+  !> @brief Syncronize Newton Under-relaxation flag
+  !<
+  function sln_sync_newtonur_flag(this, inewtonur) result(ivalue)
+    ! dummy
+    class(NumericalSolutionType) :: this !< NumericalSolutionType instance
+    integer(I4B), intent(in) :: inewtonur !< Newton Under-relaxation flag
+    ! local
+    integer(I4B) :: ivalue !< Default is set to current value (1 = under-relaxation applied)
+
+    ivalue = inewtonur
+
+  end function sln_sync_newtonur_flag
+
+  !> @brief Custom convergence check for when Newton UR has been applied
+  !<
+  function sln_nur_has_converged(this, dxold_max, hncg) &
+    result(has_converged)
+    class(NumericalSolutionType) :: this !< NumericalSolutionType instance
+    real(DP), intent(in) :: dxold_max !< the maximum dependent variable change for unrelaxed cells
+    real(DP), intent(in) :: hncg !< largest dep. var. change at end of Picard iteration
+    logical(LGP) :: has_converged !< True, when converged
+
+    has_converged = .false.
+    if (abs(dxold_max) <= this%dvclose .and. &
+        abs(hncg) <= this%dvclose) then
+      has_converged = .true.
+    end if
+
+  end function sln_nur_has_converged
+
   !> @ brief Get cell location string
   !!
   !!  Get the cell location string for the provided solution node number.
@@ -3154,6 +3200,7 @@ subroutine sln_get_loc(this, nodesln, str)
     integer(I4B) :: istart
     integer(I4B) :: iend
     integer(I4B) :: noder
+    integer(I4B) :: nglo
     !
     ! -- initialize dummy variables
     str = ''
@@ -3161,14 +3208,17 @@ subroutine sln_get_loc(this, nodesln, str)
     ! -- initialize local variables
     noder = 0
     !
+    ! -- when parallel, account for offset
+    nglo = nodesln + this%matrix_offset
+    !
     ! -- calculate and set offsets
     do i = 1, this%modellist%Count()
       mp => GetNumericalModelFromList(this%modellist, i)
       istart = 0
       iend = 0
       call mp%get_mrange(istart, iend)
-      if (nodesln >= istart .and. nodesln <= iend) then
-        noder = nodesln - istart + 1
+      if (nglo >= istart .and. nglo <= iend) then
+        noder = nglo - istart + 1
         call mp%get_mcellid(noder, str)
         exit
       end if
diff --git a/src/Solution/PETSc/PetscConvergence.F90 b/src/Solution/PETSc/PetscConvergence.F90
index 47dc0d569bb..7c4dcd2cf81 100644
--- a/src/Solution/PETSc/PetscConvergence.F90
+++ b/src/Solution/PETSc/PetscConvergence.F90
@@ -3,102 +3,175 @@ module PetscConvergenceModule
   use petscksp
   use KindModule, only: I4B, DP
   use ListModule
+  use ConvergenceSummaryModule
   implicit none
   private
 
   public :: petsc_check_convergence
-  public :: petsc_add_context
-  public :: petsc_remove_context
+  public :: KSPSetConvergenceTest
 
   type, public :: PetscContextType
     Vec :: x_old
+    Vec :: res_old
     Vec :: delta_x
+    Vec :: delta_res
     real(DP) :: dvclose
     integer(I4B) :: max_its
+    type(ConvergenceSummaryType), pointer :: cnvg_summary => null()
+  contains
+    procedure :: destroy
   end type PetscContextType
 
-  type(ListType) :: ctx_list
+  ! passing our context into PETSc requires an explicit interface
+  ! on KSPSetConvergenceTest, it is defined here:
+  interface
+    subroutine CnvgCheckFunc(ksp, n, rnorm, flag, context, ierr)
+      import tKSP, PetscContextType
+      type(tKSP) :: ksp
+      PetscInt :: n
+      PetscReal :: rnorm
+      KSPConvergedReason :: flag
+      class(PetscContextType), pointer :: context
+      PetscErrorCode :: ierr
+    end subroutine
+
+    subroutine CnvgDestroyFunc(context, ierr)
+      import PetscContextType
+      class(PetscContextType), pointer :: context
+      PetscErrorCode :: ierr
+    end subroutine
+
+    subroutine KSPSetConvergenceTest(ksp, check_convergence, context, &
+                                     destroy, ierr)
+      import tKSP, CnvgCheckFunc, PetscContextType, CnvgDestroyFunc
+      type(tKSP) :: ksp
+      procedure(CnvgCheckFunc) :: check_convergence
+      class(PetscContextType), pointer :: context
+      procedure(CnvgDestroyFunc) :: destroy
+      PetscErrorCode :: ierr
+    end subroutine
+  end interface
 
 contains
 
-  !> @brief Add a context to the static list. The
-  !! generated idx can then be used as a handle when
-  !! calling 'KSPSetConvergenceTest'. Make sure to remove
-  !< the context from this global list when done.
-  subroutine petsc_add_context(ctx, idx)
-    class(PetscContextType), pointer, intent(in) :: ctx
-    integer(I4B), intent(out) :: idx
-    ! local
-    class(*), pointer :: obj_ptr
-
-    obj_ptr => ctx
-    call ctx_list%Add(obj_ptr)
-    idx = ctx_list%Count()
-
-  end subroutine petsc_add_context
-
-  !> @brief This will clear the list with context pointers
-  !<
-  subroutine petsc_remove_context(ctx)
-    class(PetscContextType), pointer, intent(in) :: ctx
-    ! local
-    integer(I4B) :: idx
-    class(*), pointer :: obj_ptr
-
-    obj_ptr => ctx
-    idx = ctx_list%GetIndex(obj_ptr)
-    call ctx_list%RemoveNode(idx, .false.)
-
-  end subroutine petsc_remove_context
-
   !> @brief Routine to check the convergence. This is called
   !< from within PETSc.
-  subroutine petsc_check_convergence(ksp, n, rnorm, flag, ctx_id, ierr)
+  subroutine petsc_check_convergence(ksp, n, rnorm, flag, context, ierr)
     KSP :: ksp !< Iterative context
     PetscInt :: n !< Iteration number
     PetscReal :: rnorm !< 2-norm (preconditioned) residual value
     KSPConvergedReason :: flag !< Converged reason
-    PetscInt :: ctx_id !< index into the static context list
+    class(PetscContextType), pointer :: context !< context
     PetscErrorCode :: ierr !< error
     ! local
     PetscScalar, parameter :: min_one = -1.0
-    real(DP) :: norm
-    Vec :: x
-    class(PetscContextType), pointer :: petsc_context
-    class(*), pointer :: obj_ptr
-
-    ! get the context from the list
-    petsc_context => null()
-    obj_ptr => ctx_list%GetItem(ctx_id)
-    select type (obj_ptr)
-    class is (PetscContextType)
-      petsc_context => obj_ptr
-    end select
-
+    PetscScalar, dimension(:), pointer :: local_dx, local_dr
+    PetscScalar :: norm, dvmax_model, drmax_model
+    PetscInt :: idx_dv, idx_dr
+    Vec :: x, res
+    type(ConvergenceSummaryType), pointer :: summary
+    PetscInt :: iter_cnt
+    PetscInt :: i, j, istart, iend
+
+    summary => context%cnvg_summary
+
+    ! NB: KSPBuildResidual needs to have its vector destroyed
+    ! to avoid a memory leak, KSPBuildSolution doesn't...
     call KSPBuildSolution(ksp, PETSC_NULL_VEC, x, ierr)
     CHKERRQ(ierr)
+    call KSPBuildResidual(ksp, PETSC_NULL_VEC, PETSC_NULL_VEC, res, ierr)
+    CHKERRQ(ierr)
 
+    ! n == 0 is before the iteration starts
     if (n == 0) then
-      call VecCopy(x, petsc_context%x_old, ierr)
-      CHKERRQ(ierr)
-      flag = KSP_CONVERGED_ITERATING
+      if (rnorm == 0.0) then
+        ! exact solution found
+        flag = KSP_CONVERGED_HAPPY_BREAKDOWN
+      else
+        call VecCopy(x, context%x_old, ierr)
+        CHKERRQ(ierr)
+        call VecCopy(res, context%res_old, ierr)
+        CHKERRQ(ierr)
+        call VecDestroy(res, ierr)
+        CHKERRQ(ierr)
+        flag = KSP_CONVERGED_ITERATING
+      end if
       return
     end if
 
-    call VecWAXPY(petsc_context%delta_x, min_one, x, petsc_context%x_old, ierr)
+    ! increment iteration counter
+    summary%iter_cnt = summary%iter_cnt + 1
+    iter_cnt = summary%iter_cnt
+
+    if (summary%nitermax > 1) then
+      summary%itinner(iter_cnt) = n
+      do i = 1, summary%convnmod
+        summary%convdvmax(i, iter_cnt) = -huge(dvmax_model)
+        summary%convlocdv(i, iter_cnt) = -1
+        summary%convdrmax(i, iter_cnt) = -huge(drmax_model)
+        summary%convlocdr(i, iter_cnt) = -1
+      end do
+    end if
+
+    call VecWAXPY(context%delta_x, min_one, context%x_old, x, ierr)
+    CHKERRQ(ierr)
+
+    call VecWAXPY(context%delta_res, min_one, context%res_old, res, ierr)
+    CHKERRQ(ierr)
+
+    call VecNorm(context%delta_x, NORM_INFINITY, norm, ierr)
     CHKERRQ(ierr)
 
-    call VecNorm(petsc_context%delta_x, NORM_INFINITY, norm, ierr)
+    call VecCopy(x, context%x_old, ierr)
     CHKERRQ(ierr)
 
-    call VecCopy(x, petsc_context%x_old, ierr)
+    call VecCopy(res, context%res_old, ierr)
     CHKERRQ(ierr)
 
-    if (norm < petsc_context%dvclose) then
+    call VecDestroy(res, ierr)
+    CHKERRQ(ierr)
+
+    ! get dv and dr per local model
+    call VecGetArrayF90(context%delta_x, local_dx, ierr)
+    CHKERRQ(ierr)
+    call VecGetArrayF90(context%delta_res, local_dr, ierr)
+    CHKERRQ(ierr)
+    do i = 1, summary%convnmod
+      ! reset
+      dvmax_model = 0.0
+      idx_dv = -1
+      drmax_model = 0.0
+      idx_dr = -1
+      ! get first and last model index
+      istart = summary%model_bounds(i)
+      iend = summary%model_bounds(i + 1) - 1
+      do j = istart, iend
+        if (abs(local_dx(j)) > abs(dvmax_model)) then
+          dvmax_model = local_dx(j)
+          idx_dv = j
+        end if
+        if (abs(local_dr(j)) > abs(drmax_model)) then
+          drmax_model = local_dr(j)
+          idx_dr = j
+        end if
+      end do
+      if (summary%nitermax > 1) then
+        summary%convdvmax(i, iter_cnt) = dvmax_model
+        summary%convlocdv(i, iter_cnt) = idx_dv
+        summary%convdrmax(i, iter_cnt) = drmax_model
+        summary%convlocdr(i, iter_cnt) = idx_dr
+      end if
+    end do
+    call VecRestoreArrayF90(x, local_dx, ierr)
+    CHKERRQ(ierr)
+    call VecRestoreArrayF90(x, local_dr, ierr)
+    CHKERRQ(ierr)
+
+    if (norm < context%dvclose) then
       flag = KSP_CONVERGED_HAPPY_BREAKDOWN ! Converged
     else
       flag = KSP_CONVERGED_ITERATING ! Not yet converged
-      if (n == petsc_context%max_its) then
+      if (n == context%max_its) then
         ! ran out of iterations before convergence
         ! has been reached
         flag = KSP_DIVERGED_ITS
@@ -107,4 +180,20 @@ subroutine petsc_check_convergence(ksp, n, rnorm, flag, ctx_id, ierr)
 
   end subroutine petsc_check_convergence
 
+  subroutine destroy(this)
+    class(PetscContextType) :: this
+    ! local
+    integer(I4B) :: ierr
+
+    call VecDestroy(this%x_old, ierr)
+    CHKERRQ(ierr)
+    call VecDestroy(this%res_old, ierr)
+    CHKERRQ(ierr)
+    call VecDestroy(this%delta_x, ierr)
+    CHKERRQ(ierr)
+    call VecDestroy(this%delta_res, ierr)
+    CHKERRQ(ierr)
+
+  end subroutine destroy
+
 end module PetscConvergenceModule
diff --git a/src/Solution/PETSc/PetscImsPreconditioner.F90 b/src/Solution/PETSc/PetscImsPreconditioner.F90
new file mode 100644
index 00000000000..c5f834ad440
--- /dev/null
+++ b/src/Solution/PETSc/PetscImsPreconditioner.F90
@@ -0,0 +1,80 @@
+module PetscImsPreconditionerModule
+#include <petsc/finclude/petscksp.h>
+  use petscksp
+
+  implicit none
+  private
+
+  public :: PcShellCtxType
+  public :: pcshell_apply
+  public :: pcshell_setup
+  public :: pcshell_destroy
+
+  type :: PcShellCtxType
+    Vec :: diag
+  end type
+
+  interface
+    subroutine PCShellGetContext(pc, ctx, ierr)
+      import PcShellCtxType, tPC
+      type(tPC) :: pc
+      type(PcShellCtxType), pointer :: ctx
+      integer :: ierr
+    end subroutine
+  end interface
+
+contains
+
+  !> @brief Apply shell preconditioner
+  !<
+  subroutine pcshell_apply(pc, x, y, ierr)
+    PC :: pc !< the shell preconditioner
+    Vec :: x !< the input vector
+    Vec :: y !< the output vector
+    PetscErrorCode :: ierr !< PETSc error code
+    ! local
+    type(PcShellCtxType), pointer :: pc_ctx => null()
+
+    ! this applies an example jacobi pc,
+    ! to be replaced by others (MILUT)
+    call PCShellGetContext(pc, pc_ctx, ierr)
+    CHKERRQ(ierr)
+    call VecPointwiseMult(y, x, pc_ctx%diag, ierr)
+    CHKERRQ(ierr)
+
+  end subroutine pcshell_apply
+
+  !> @brief Set up the custom preconditioner
+  !<
+  subroutine pcshell_setup(pc, ierr)
+    PC :: pc !< the shell preconditioner
+    PetscErrorCode :: ierr !< PETSc error code
+    ! local
+    Mat :: pmat
+    type(PcShellCtxType), pointer :: pc_ctx => null()
+
+    ! this currently sets up an example jacobi pc,
+    ! to be replaced by others (MILUT)
+    call PCShellGetContext(pc, pc_ctx, ierr)
+    CHKERRQ(ierr)
+    call PCGetOperators(pc, PETSC_NULL_MAT, pmat, ierr)
+    CHKERRQ(ierr)
+    call MatCreateVecs(pmat, pc_ctx%diag, PETSC_NULL_VEC, ierr)
+    CHKERRQ(ierr)
+    call MatGetDiagonal(pmat, pc_ctx%diag, ierr)
+    CHKERRQ(ierr)
+    call VecReciprocal(pc_ctx%diag, ierr)
+    CHKERRQ(ierr)
+
+  end subroutine pcshell_setup
+
+  !> @brief Clean up
+  !<
+  subroutine pcshell_destroy(pc, ierr)
+    PC :: pc !< the shell preconditioner
+    PetscErrorCode :: ierr !< PETSc error code
+    ! local
+
+  end subroutine pcshell_destroy
+
+end module PetscImsPreconditionerModule
diff --git a/src/Solution/PETSc/PetscSolver.F90 b/src/Solution/PETSc/PetscSolver.F90
index bec64d17b9c..fdfd83cbb25 100644
--- a/src/Solution/PETSc/PetscSolver.F90
+++ b/src/Solution/PETSc/PetscSolver.F90
@@ -2,12 +2,18 @@ module PetscSolverModule
 #include <petsc/finclude/petscksp.h>
   use petscksp
   use KindModule, only: I4B, DP, LGP
+  use ConstantsModule, only: LINELENGTH
   use LinearSolverBaseModule
   use MatrixBaseModule
   use VectorBaseModule
   use PetscMatrixModule
   use PetscVectorModule
   use PetscConvergenceModule
+  use PetscImsPreconditionerModule
+  use ConvergenceSummaryModule
+  use ImsLinearSettingsModule
+  use SimVariablesModule, only: iout, simulation_mode
+  use SimModule, only: store_error
 
   implicit none
   private
@@ -16,26 +22,37 @@ module PetscSolverModule
 
   type, public, extends(LinearSolverBaseType) :: PetscSolverType
     KSP :: ksp_petsc
-    class(PetscMatrixType), pointer :: matrix
-    Mat, pointer :: mat_petsc
-    Vec, pointer :: vec_residual
+    class(PetscMatrixType), pointer :: matrix => null()
+    Mat, pointer :: mat_petsc => null()
+    Vec, pointer :: vec_residual => null()
 
-    integer(I4B) :: lin_accel_type
+    logical(LGP) :: use_ims_pc !< when true, use custom IMS-style preconditioning
     real(DP) :: dvclose
-    class(PetscContextType), pointer :: petsc_ctx
-    integer(I4B) :: ctx_idx
+    integer(I4B) :: pc_levels
+    real(DP) :: drop_tolerance
+    KSPType :: ksp_type
+    PCType :: pc_type
+    PCType :: sub_pc_type
+    class(PetscContextType), pointer :: petsc_ctx => null()
+    type(PcShellCtxType), pointer :: pc_context => null()
+    type(ConvergenceSummaryType), pointer :: convergence_summary => null()
+
   contains
     procedure :: initialize => petsc_initialize
     procedure :: solve => petsc_solve
     procedure :: get_result => petsc_get_result
+    procedure :: print_summary => petsc_print_summary
     procedure :: destroy => petsc_destroy
     procedure :: create_matrix => petsc_create_matrix
 
     ! private
-    procedure, private :: get_options
+    procedure, private :: get_options_mf6
     procedure, private :: create_ksp
     procedure, private :: create_convergence_check
+    procedure, private :: set_petsc_pc
+    procedure, private :: set_ims_pc
     procedure, private :: print_vec
+    procedure, private :: print_petsc_version
   end type PetscSolverType
 
 contains
@@ -56,11 +73,19 @@ end function create_petsc_solver
 
   !> @brief Initialize PETSc KSP solver with
   !<  options from the petsc database file
-  subroutine petsc_initialize(this, matrix)
+  subroutine petsc_initialize(this, matrix, linear_settings, convergence_summary)
     class(PetscSolverType) :: this !< This solver instance
     class(MatrixBaseType), pointer :: matrix !< The solution matrix as KSP operator
+    type(ImsLinearSettingsType), pointer :: linear_settings !< the settings for the linear solver from the .ims file
+    type(ConvergenceSummaryType), pointer :: convergence_summary !< a convergence record for diagnostics
     ! local
     PetscErrorCode :: ierr
+    character(len=LINELENGTH) :: errmsg
+
+    this%use_ims_pc = .false.
+    allocate (this%pc_context)
+
+    call this%print_petsc_version()
 
     this%mat_petsc => null()
     select type (pm => matrix)
@@ -73,36 +98,85 @@ subroutine petsc_initialize(this, matrix)
     call MatCreateVecs(this%mat_petsc, this%vec_residual, PETSC_NULL_VEC, ierr)
     CHKERRQ(ierr)
 
-    ! get options from PETSc database file
-    call this%get_options()
+    ! configure from IMS settings
+    this%dvclose = linear_settings%dvclose
+    this%nitermax = linear_settings%iter1
+
+    if (linear_settings%ilinmeth == 1) then
+      this%ksp_type = KSPCG
+    else if (linear_settings%ilinmeth == 2) then
+      this%ksp_type = KSPBCGS
+    else
+      write (errmsg, '(a)') 'PETSc: unknown linear solver method.'
+      call store_error(errmsg)
+    end if
+
+    if (simulation_mode == "PARALLEL") then
+      this%pc_type = PCBJACOBI
+      this%sub_pc_type = PCILU
+    else
+      this%pc_type = PCILU
+      this%sub_pc_type = PCNONE
+    end if
+    this%pc_levels = linear_settings%level
+    this%drop_tolerance = linear_settings%droptol
+
+    ! get MODFLOW options from PETSc database file
+    call this%get_options_mf6()
 
     ! create the solver object
     call this%create_ksp()
 
     ! Create custom convergence check
-    call this%create_convergence_check()
+    call this%create_convergence_check(convergence_summary)
 
   end subroutine petsc_initialize
 
-  !> @brief Get the PETSc options from the database
+  !> @brief Print PETSc version string from shared lib
   !<
-  subroutine get_options(this)
+  subroutine print_petsc_version(this)
+    class(PetscSolverType) :: this
+    ! local
+    PetscErrorCode :: ierr
+    PetscInt :: major, minor, subminor, release
+    character(len=128) :: petsc_version, release_str
+
+    call PetscGetVersionNumber(major, minor, subminor, release, ierr)
+    CHKERRQ(ierr)
+
+    if (release == 1) then
+      release_str = "(release)"
+    else
+      release_str = "(unofficial)"
+    end if
+    write (petsc_version, '(i0,a,i0,a,i0,a,a)') &
+      major, ".", minor, ".", subminor, " ", trim(release_str)
+    write (iout, '(/,1x,2a,/)') &
+      "PETSc Linear Solver will be used: version ", petsc_version
+
+  end subroutine print_petsc_version
+
+  !> @brief Get the MODFLOW specific options from the PETSc database
+  !<
+  subroutine get_options_mf6(this)
     class(PetscSolverType) :: this
     ! local
     PetscErrorCode :: ierr
     logical(LGP) :: found
 
-    this%dvclose = 0.01_DP
     call PetscOptionsGetReal(PETSC_NULL_OPTIONS, PETSC_NULL_CHARACTER, &
                              '-dvclose', this%dvclose, found, ierr)
     CHKERRQ(ierr)
 
-    this%nitermax = 100
     call PetscOptionsGetInt(PETSC_NULL_OPTIONS, PETSC_NULL_CHARACTER, &
                             '-nitermax', this%nitermax, found, ierr)
     CHKERRQ(ierr)
 
-  end subroutine get_options
+    call PetscOptionsGetBool(PETSC_NULL_OPTIONS, PETSC_NULL_CHARACTER, &
+                             '-ims_pc', this%use_ims_pc, found, ierr)
+    CHKERRQ(ierr)
+
+  end subroutine get_options_mf6
 
   !> @brief Create the PETSc KSP object
   !<
@@ -114,49 +188,159 @@ subroutine create_ksp(this)
     call KSPCreate(PETSC_COMM_WORLD, this%ksp_petsc, ierr)
     CHKERRQ(ierr)
 
+    call KSPSetOperators(this%ksp_petsc, this%mat_petsc, this%mat_petsc, ierr)
+    CHKERRQ(ierr)
+
     call KSPSetInitialGuessNonzero(this%ksp_petsc, .true., ierr)
     CHKERRQ(ierr)
 
-    call KSPSetFromOptions(this%ksp_petsc, ierr)
+    call KSPSetType(this%ksp_petsc, this%ksp_type, ierr)
     CHKERRQ(ierr)
 
-    call KSPSetOperators(this%ksp_petsc, this%mat_petsc, this%mat_petsc, ierr)
+    if (this%use_ims_pc) then
+      call this%set_ims_pc()
+    else
+      call this%set_petsc_pc()
+    end if
+
+    ! finally override these options from the
+    ! optional .petscrc file
+    call KSPSetFromOptions(this%ksp_petsc, ierr)
     CHKERRQ(ierr)
 
   end subroutine create_ksp
 
+  !> @brief Set up a standard PETSc preconditioner from
+  !< the configured settings
+  subroutine set_petsc_pc(this)
+    class(PetscSolverType) :: this !< This solver instance
+    ! local
+    PC :: pc, sub_pc
+    KSP, dimension(1) :: sub_ksp
+    PetscInt :: n_local, n_first
+    PetscErrorCode :: ierr
+
+    call KSPGetPC(this%ksp_petsc, pc, ierr)
+    CHKERRQ(ierr)
+
+    call PCSetType(pc, this%pc_type, ierr)
+    CHKERRQ(ierr)
+
+    call PCSetFromOptions(pc, ierr)
+    CHKERRQ(ierr)
+
+    call PCSetUp(pc, ierr)
+    CHKERRQ(ierr)
+
+    if (simulation_mode == "PARALLEL") then
+      call PCBJacobiGetSubKSP(pc, n_local, n_first, sub_ksp, ierr)
+      CHKERRQ(ierr)
+      call KSPGetPC(sub_ksp(1), sub_pc, ierr)
+      CHKERRQ(ierr)
+      call PCSetType(sub_pc, this%sub_pc_type, ierr)
+      CHKERRQ(ierr)
+      call PCFactorSetLevels(sub_pc, this%pc_levels, ierr)
+      CHKERRQ(ierr)
+    else
+      call PCFactorSetLevels(pc, this%pc_levels, ierr)
+      CHKERRQ(ierr)
+    end if
+
+  end subroutine set_petsc_pc
+
+  !> @brief Set up a custom preconditioner following the ones
+  !< we have in IMS, i.e. Modified ILU(T)
+  subroutine set_ims_pc(this)
+    class(PetscSolverType) :: this !< This solver instance
+    ! local
+    PC :: pc, sub_pc
+    KSP, dimension(1) :: sub_ksp
+    PetscInt :: n_local, n_first
+    PetscErrorCode :: ierr
+
+    if (simulation_mode == "PARALLEL") then
+      this%sub_pc_type = PCSHELL
+
+      call KSPGetPC(this%ksp_petsc, pc, ierr)
+      CHKERRQ(ierr)
+      call PCSetType(pc, this%pc_type, ierr)
+      CHKERRQ(ierr)
+      call PCSetUp(pc, ierr)
+      CHKERRQ(ierr)
+      call PCBJacobiGetSubKSP(pc, n_local, n_first, sub_ksp, ierr)
+      CHKERRQ(ierr)
+      call KSPGetPC(sub_ksp(1), sub_pc, ierr)
+      CHKERRQ(ierr)
+      call PCSetType(sub_pc, this%sub_pc_type, ierr)
+      CHKERRQ(ierr)
+      call PCShellSetApply(sub_pc, pcshell_apply, ierr)
+      CHKERRQ(ierr)
+      call PCShellSetSetUp(sub_pc, pcshell_setup, ierr)
+      CHKERRQ(ierr)
+      call PCShellSetDestroy(sub_pc, pcshell_destroy, ierr)
+      CHKERRQ(ierr)
+      call PCShellSetContext(sub_pc, this%pc_context, ierr)
+      CHKERRQ(ierr)
+    else
+      this%pc_type = PCSHELL
+
+      call KSPGetPC(this%ksp_petsc, pc, ierr)
+      CHKERRQ(ierr)
+      call PCSetType(pc, PCSHELL, ierr)
+      CHKERRQ(ierr)
+      call PCShellSetApply(pc, pcshell_apply, ierr)
+      CHKERRQ(ierr)
+      call PCShellSetSetUp(pc, pcshell_setup, ierr)
+      CHKERRQ(ierr)
+      call PCShellSetDestroy(pc, pcshell_destroy, ierr)
+      CHKERRQ(ierr)
+      call PCShellSetContext(pc, this%pc_context, ierr)
+      CHKERRQ(ierr)
+    end if
+
+  end subroutine set_ims_pc
+
   !> @brief Create and assign a custom convergence
   !< check for this solver
-  subroutine create_convergence_check(this)
+  subroutine create_convergence_check(this, convergence_summary)
     class(PetscSolverType) :: this !< This solver instance
+    type(ConvergenceSummaryType), pointer :: convergence_summary
     ! local
     PetscErrorCode :: ierr
 
     this%petsc_ctx%dvclose = this%dvclose
     this%petsc_ctx%max_its = this%nitermax
+    this%petsc_ctx%cnvg_summary => convergence_summary
     call MatCreateVecs( &
       this%mat_petsc, this%petsc_ctx%x_old, PETSC_NULL_VEC, ierr)
     CHKERRQ(ierr)
     call MatCreateVecs( &
       this%mat_petsc, this%petsc_ctx%delta_x, PETSC_NULL_VEC, ierr)
     CHKERRQ(ierr)
-    call petsc_add_context(this%petsc_ctx, this%ctx_idx)
+    call MatCreateVecs( &
+      this%mat_petsc, this%petsc_ctx%res_old, PETSC_NULL_VEC, ierr)
+    CHKERRQ(ierr)
+    call MatCreateVecs( &
+      this%mat_petsc, this%petsc_ctx%delta_res, PETSC_NULL_VEC, ierr)
+    CHKERRQ(ierr)
 
     call KSPSetConvergenceTest(this%ksp_petsc, petsc_check_convergence, &
-                               this%ctx_idx, PETSC_NULL_FUNCTION, ierr)
+                               this%petsc_ctx, PETSC_NULL_FUNCTION, ierr)
     CHKERRQ(ierr)
 
   end subroutine create_convergence_check
 
-  subroutine petsc_solve(this, kiter, rhs, x)
+  subroutine petsc_solve(this, kiter, rhs, x, cnvg_summary)
     class(PetscSolverType) :: this
     integer(I4B) :: kiter
     class(VectorBaseType), pointer :: rhs
     class(VectorBaseType), pointer :: x
+    type(ConvergenceSummaryType) :: cnvg_summary
     ! local
     PetscErrorCode :: ierr
     class(PetscVectorType), pointer :: rhs_petsc, x_petsc
     KSPConvergedReason :: icnvg
+    integer :: it_number
 
     rhs_petsc => null()
     select type (rhs)
@@ -172,13 +356,17 @@ subroutine petsc_solve(this, kiter, rhs, x)
 
     this%iteration_number = 0
     this%is_converged = 0
+    if (kiter == 1) then
+      this%petsc_ctx%cnvg_summary%iter_cnt = 0
+    end if
 
     ! update matrix coefficients
     call this%matrix%update()
     call KSPSolve(this%ksp_petsc, rhs_petsc%vec_impl, x_petsc%vec_impl, ierr)
     CHKERRQ(ierr)
 
-    call KSPGetIterationNumber(this%ksp_petsc, this%iteration_number, ierr)
+    call KSPGetIterationNumber(this%ksp_petsc, it_number, ierr)
+    this%iteration_number = it_number
     call KSPGetConvergedReason(this%ksp_petsc, icnvg, ierr)
     if (icnvg > 0) this%is_converged = 1
 
@@ -188,6 +376,35 @@ subroutine petsc_get_result(this)
     class(PetscSolverType) :: this
   end subroutine petsc_get_result
 
+  subroutine petsc_print_summary(this)
+    class(PetscSolverType) :: this
+    ! local
+    character(len=128) :: ksp_type, pc_type, dvclose_str
+    integer :: ierr
+    PC :: pc
+
+    call KSPGetType(this%ksp_petsc, ksp_type, ierr)
+    CHKERRQ(ierr)
+    call KSPGetPC(this%ksp_petsc, pc, ierr)
+    CHKERRQ(ierr)
+    call PCGetType(pc, pc_type, ierr)
+    CHKERRQ(ierr)
+    write (dvclose_str, '(e15.5)') this%dvclose
+
+    write (iout, '(/,7x,a)') "PETSc linear solver settings: "
+    write (iout, '(1x,a)') repeat('-', 66)
+    write (iout, '(1x,a,a)') "Linear acceleration method:   ", trim(this%ksp_type)
+    write (iout, '(1x,a,a)') "Preconditioner type:          ", trim(this%pc_type)
+    if (simulation_mode == "PARALLEL") then
+      write (iout, '(1x,a,a)') "Sub-preconditioner type:      ", &
+        trim(this%sub_pc_type)
+    end if
+    write (iout, '(1x,a,i0)') "Maximum nr. of iterations:    ", this%nitermax
+    write (iout, '(1x,a,a,/)') &
+      "Dep. var. closure criterion:  ", trim(adjustl(dvclose_str))
+
+  end subroutine petsc_print_summary
+
   subroutine petsc_destroy(this)
     class(PetscSolverType) :: this
     ! local
@@ -202,12 +419,11 @@ subroutine petsc_destroy(this)
     deallocate (this%vec_residual)
 
     ! delete context
-    call VecDestroy(this%petsc_ctx%delta_x, ierr)
-    CHKERRQ(ierr)
-    call VecDestroy(this%petsc_ctx%x_old, ierr)
-    CHKERRQ(ierr)
+    call this%petsc_ctx%destroy()
     deallocate (this%petsc_ctx)
 
+    deallocate (this%pc_context)
+
   end subroutine petsc_destroy
 
   function petsc_create_matrix(this) result(matrix)
diff --git a/src/Solution/ParallelSolution.f90 b/src/Solution/ParallelSolution.f90
index b97bbf45132..687755e71ae 100644
--- a/src/Solution/ParallelSolution.f90
+++ b/src/Solution/ParallelSolution.f90
@@ -1,6 +1,6 @@
 module ParallelSolutionModule
   use KindModule, only: DP, LGP, I4B
-  use ConstantsModule, only: DONE, DZERO
+  use ConstantsModule, only: LENPAKLOC, DONE, DZERO
   use NumericalSolutionModule, only: NumericalSolutionType
   use mpi
   use MpiWorldModule
@@ -13,8 +13,13 @@ module ParallelSolutionModule
   contains
     ! override
     procedure :: sln_has_converged => par_has_converged
+    procedure :: sln_package_convergence => par_package_convergence
+    procedure :: sln_sync_newtonur_flag => par_sync_newtonur_flag
+    procedure :: sln_nur_has_converged => par_nur_has_converged
     procedure :: sln_calc_ptc => par_calc_ptc
     procedure :: sln_underrelax => par_underrelax
+    procedure :: sln_backtracking_xupdate => par_backtracking_xupdate
+
   end type ParallelSolutionType
 
 contains
@@ -44,6 +49,69 @@ function par_has_converged(this, max_dvc) result(has_converged)
 
   end function par_has_converged
 
+  function par_package_convergence(this, dpak, cpakout, iend) &
+    result(icnvg_global)
+    class(ParallelSolutionType) :: this !< parallel solution instance
+    real(DP), intent(in) :: dpak !< Newton Under-relaxation flag
+    character(len=LENPAKLOC), intent(in) :: cpakout
+    integer(I4B), intent(in) :: iend
+    ! local
+    integer(I4B) :: icnvg_global
+    integer(I4B) :: icnvg_local
+    integer :: ierr
+    type(MpiWorldType), pointer :: mpi_world
+
+    mpi_world => get_mpi_world()
+
+    icnvg_local = &
+      this%NumericalSolutionType%sln_package_convergence(dpak, cpakout, iend)
+
+    call MPI_Allreduce(icnvg_local, icnvg_global, 1, MPI_INTEGER, &
+                       MPI_MIN, mpi_world%comm, ierr)
+
+  end function par_package_convergence
+
+  function par_sync_newtonur_flag(this, inewtonur) result(ivalue)
+    class(ParallelSolutionType) :: this !< parallel solution instance
+    integer(I4B), intent(in) :: inewtonur !< local Newton Under-relaxation flag
+    ! local
+    integer(I4B) :: ivalue !< Maximum of all local values (1 = under-relaxation applied)
+    integer :: ierr
+    type(MpiWorldType), pointer :: mpi_world
+
+    mpi_world => get_mpi_world()
+    call MPI_Allreduce(inewtonur, ivalue, 1, MPI_INTEGER, &
+                       MPI_MAX, mpi_world%comm, ierr)
+
+  end function par_sync_newtonur_flag
+
+  function par_nur_has_converged(this, dxold_max, hncg) &
+    result(has_converged)
+    class(ParallelSolutionType) :: this !< parallel solution instance
+    real(DP), intent(in) :: dxold_max !< the maximum dependent variable change for cells not adjusted by NUR
+    real(DP), intent(in) :: hncg !< largest dep. var. change at end of Picard iter.
+    logical(LGP) :: has_converged !< True, when converged
+    ! local
+    integer(I4B) :: icnvg_local
+    integer(I4B) :: icnvg_global
+    integer :: ierr
+    type(MpiWorldType), pointer :: mpi_world
+
+    mpi_world => get_mpi_world()
+
+    has_converged = .false.
+    icnvg_local = 0
+    if (this%NumericalSolutionType%sln_nur_has_converged( &
+        dxold_max, hncg)) then
+      icnvg_local = 1
+    end if
+
+    call MPI_Allreduce(icnvg_local, icnvg_global, 1, MPI_INTEGER, &
+                       MPI_MIN, mpi_world%comm, ierr)
+    if (icnvg_global == 1) has_converged = .true.
+
+  end function par_nur_has_converged
+
   !> @brief Calculate pseudo-transient continuation factor
   !< for the parallel case
   subroutine par_calc_ptc(this, iptc, ptcf)
@@ -106,4 +174,25 @@ subroutine par_underrelax(this, kiter, bigch, neq, active, x, xtemp)
 
   end subroutine par_underrelax
 
+  !> @brief synchronize backtracking flag over processes
+  !<
+  subroutine par_backtracking_xupdate(this, btflag)
+    ! -- dummy variables
+    class(ParallelSolutionType), intent(inout) :: this !< ParallelSolutionType instance
+    integer(I4B), intent(inout) :: btflag !< global backtracking flag (1) backtracking performed (0) backtracking not performed
+    ! -- local variables
+    integer(I4B) :: btflag_local
+    type(MpiWorldType), pointer :: mpi_world
+    integer :: ierr
+
+    mpi_world => get_mpi_world()
+
+    btflag_local = 0
+    call this%NumericalSolutionType%sln_backtracking_xupdate(btflag_local)
+
+    call MPI_Allreduce(btflag_local, btflag, 1, MPI_INTEGER, &
+                       MPI_MAX, mpi_world%comm, ierr)
+
+  end subroutine par_backtracking_xupdate
+
 end module ParallelSolutionModule
diff --git a/src/Timing/tdis.f90 b/src/Timing/tdis.f90
index b1dee473e7a..0aa32fc93bb 100644
--- a/src/Timing/tdis.f90
+++ b/src/Timing/tdis.f90
@@ -5,7 +5,7 @@
 module TdisModule
 
   use KindModule, only: DP, I4B, LGP
-  use SimVariablesModule, only: iout
+  use SimVariablesModule, only: iout, isim_level
   use BlockParserModule, only: BlockParserType
   use ConstantsModule, only: LINELENGTH, LENDATETIME, VALL
   !
@@ -45,13 +45,9 @@ module TdisModule
 
 contains
 
+  !> @brief Create temporal discretization
+  !<
   subroutine tdis_cr(fname)
-! ******************************************************************************
-! tdis_cr -- create temporal discretization.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use InputOutputModule, only: getunit, openfile
     use ConstantsModule, only: LINELENGTH, DZERO
@@ -64,7 +60,6 @@ subroutine tdis_cr(fname)
     character(len=*), parameter :: fmtheader = &
      "(1X,/1X,'TDIS -- TEMPORAL DISCRETIZATION PACKAGE,',   /                  &
       &' VERSION 1 : 11/13/2014 - INPUT READ FROM UNIT ',I4)"
-! ------------------------------------------------------------------------------
     !
     ! -- Allocate the scalar variables
     call tdis_allocate_scalars()
@@ -99,21 +94,17 @@ subroutine tdis_cr(fname)
       call ats_cr(inats, nper)
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine tdis_cr
 
+  !> @brief Set kstp and kper
+  !<
   subroutine tdis_set_counters()
-! ******************************************************************************
-! tdis_set_counters -- Set kstp and kper
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DONE, DZERO, MNORMAL, MVALIDATE, DNODATA
     use SimVariablesModule, only: isim_mode
-    use GenericUtilitiesModule, only: sim_message
+    use MessageModule, only: write_message
     use AdaptiveTimeStepModule, only: isAdaptivePeriod, dtstable, &
                                       ats_period_message
     ! -- local
@@ -126,12 +117,11 @@ subroutine tdis_set_counters()
     character(len=*), parameter :: fmtvspts = &
       &"(' Validating:  Stress period: ',i5,4x,'Time step: ',i5,4x)"
     character(len=*), parameter :: fmtspi = &
-      "('1',/28X,'STRESS PERIOD NO. ',I0,', LENGTH =',G15.7,/ &
-      &28X,47('-'))"
+      "('1',/1X,'STRESS PERIOD NO. ',I0,', LENGTH =',G15.7,/ &
+      &1X,42('-'))"
     character(len=*), parameter :: fmtspits = &
-      "(28X,'NUMBER OF TIME STEPS = ',I0,/ &
-      &28X,'MULTIPLIER FOR DELT =',F10.3)"
-! ------------------------------------------------------------------------------
+      "(1X,'NUMBER OF TIME STEPS = ',I0,/ &
+      &1X,'MULTIPLIER FOR DELT =',F10.3)"
     !
     ! -- Initialize variables for this step
     if (inats > 0) dtstable = DNODATA
@@ -155,8 +145,9 @@ subroutine tdis_set_counters()
     case (MNORMAL)
       write (line, fmtspts) cpref, kper, kstp, trim(cend)
     end select
-    call sim_message(line, level=VALL)
-    call sim_message(line, iunit=iout, skipbefore=1, skipafter=1)
+    if (isim_level >= VALL) &
+      call write_message(line)
+    call write_message(line, iunit=iout, skipbefore=1, skipafter=1)
     !
     ! -- Write message if first time step
     if (kstp == 1) then
@@ -168,17 +159,13 @@ subroutine tdis_set_counters()
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine tdis_set_counters
 
+  !> @brief Set time step length
+  !<
   subroutine tdis_set_timestep()
-! ******************************************************************************
-! tdis_set_timestep -- Set time step length
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DONE, DZERO
     use AdaptiveTimeStepModule, only: isAdaptivePeriod, &
@@ -188,8 +175,7 @@ subroutine tdis_set_timestep()
     logical(LGP) :: adaptivePeriod
     ! -- format
     character(len=*), parameter :: fmttsi = &
-                                   "(28X,'INITIAL TIME STEP SIZE =',G15.7)"
-! ------------------------------------------------------------------------------
+                                   "(1X,'INITIAL TIME STEP SIZE =',G15.7)"
     !
     ! -- Initialize
     adaptivePeriod = isAdaptivePeriod(kper)
@@ -233,19 +219,16 @@ subroutine tdis_set_timestep()
       endofsimulation = .true.
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine tdis_set_timestep
 
+  !> @brief Reset delt and update timing variables and indicators
+  !!
+  !! This routine is called when a timestep fails to converge, and so it is
+  !! retried using a smaller time step (deltnew).
+  !<
   subroutine tdis_delt_reset(deltnew)
-! ******************************************************************************
-! tdis_delt_reset -- reset delt and update timing variables and indicators.
-!   This routine is called when a timestep fails to converge, and so it is
-!   retried using a smaller time step (deltnew).
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DONE, DZERO
     use AdaptiveTimeStepModule, only: isAdaptivePeriod, &
@@ -255,7 +238,6 @@ subroutine tdis_delt_reset(deltnew)
     real(DP), intent(in) :: deltnew
     ! -- local
     logical(LGP) :: adaptivePeriod
-! ------------------------------------------------------------------------------
     !
     ! -- Set values
     adaptivePeriod = isAdaptivePeriod(kper)
@@ -279,21 +261,15 @@ subroutine tdis_delt_reset(deltnew)
       totim = totalsimtime
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine tdis_delt_reset
 
+  !> @brief Set time step length
+  !<
   subroutine tdis_set_delt()
-! ******************************************************************************
-! tdis_set_delt -- Set time step length
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: DONE
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     if (kstp == 1) then
       ! -- Calculate the first value of delt for this stress period
@@ -313,7 +289,7 @@ subroutine tdis_set_delt()
       delt = tsmult(kper) * delt
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine tdis_set_delt
 
@@ -373,96 +349,91 @@ end subroutine tdis_set_delt
 !      totim = totalsimtime
 !    end if
 !    !
-!    ! -- return
+!    ! -- Return
 !    return
 !  end subroutine tdis_set_delt_std
 
+  !> @brief Print simulation time
+  !<
   subroutine tdis_ot(iout)
-! ******************************************************************************
-!     PRINT SIMULATION TIME
-! ******************************************************************************
-!
-!        SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
+    use ConstantsModule, only: DZERO, DONE, DSIXTY, DSECPERHR, DHRPERDAY, &
+                               DDYPERYR, DSECPERDY, DSECPERYR
     ! -- dummy
     integer(I4B), intent(in) :: iout
     ! -- local
-    real(DP) :: zero, cnv, delsec, totsec, persec, sixty, hrday, dayyr, &
-                delmn, delhr, totmn, tothr, totdy, totyr, permn, perhr, &
-                perdy, peryr, deldy, delyr
-! ------------------------------------------------------------------------------
-    WRITE (IOUT, 199) KSTP, KPER
-199 FORMAT(1X, ///9X, 'TIME SUMMARY AT END OF TIME STEP', I5, &
-     &     ' IN STRESS PERIOD ', I4)
-!C
-!C1------USE TIME UNIT INDICATOR TO GET FACTOR TO CONVERT TO SECONDS.
-    ZERO = 0.d0
-    CNV = ZERO
-    IF (ITMUNI .EQ. 1) CNV = 1.
-    IF (ITMUNI .EQ. 2) CNV = 60.
-    IF (ITMUNI .EQ. 3) CNV = 3600.
-    IF (ITMUNI .EQ. 4) CNV = 86400.
-    IF (ITMUNI .EQ. 5) CNV = 31557600.
-!C
-!C2------IF FACTOR=0 THEN TIME UNITS ARE NON-STANDARD.
-    IF (CNV .NE. ZERO) GO TO 100
-!C
-!C2A-----PRINT TIMES IN NON-STANDARD TIME UNITS.
-    WRITE (IOUT, 301) DELT, PERTIM, TOTIM
-301 FORMAT(21X, '     TIME STEP LENGTH =', G15.6 / &
-     &       21X, '   STRESS PERIOD TIME =', G15.6 / &
-     &       21X, 'TOTAL SIMULATION TIME =', G15.6)
-!C
-!C2B-----RETURN
-    RETURN
-!C
-!C3------CALCULATE LENGTH OF TIME STEP & ELAPSED TIMES IN SECONDS.
-100 DELSEC = CNV * DELT
-    TOTSEC = CNV * TOTIM
-    PERSEC = CNV * PERTIM
-!C
-!C4------CALCULATE TIMES IN MINUTES,HOURS,DAYS AND YEARS.
-    SIXTY = 60.
-    HRDAY = 24.
-    DAYYR = 365.25
-    DELMN = DELSEC / SIXTY
-    DELHR = DELMN / SIXTY
-    DELDY = DELHR / HRDAY
-    DELYR = DELDY / DAYYR
-    TOTMN = TOTSEC / SIXTY
-    TOTHR = TOTMN / SIXTY
-    TOTDY = TOTHR / HRDAY
-    TOTYR = TOTDY / DAYYR
-    PERMN = PERSEC / SIXTY
-    PERHR = PERMN / SIXTY
-    PERDY = PERHR / HRDAY
-    PERYR = PERDY / DAYYR
-!C
-!C5------PRINT TIME STEP LENGTH AND ELAPSED TIMES IN ALL TIME UNITS.
-    WRITE (IOUT, 200)
-200 FORMAT(19X, ' SECONDS     MINUTES      HOURS', 7X, &
-     &    'DAYS        YEARS'/20X, 59('-'))
-    write (IOUT, 201) DELSEC, DELMN, DELHR, DELDY, DELYR
-201 FORMAT(1X, '  TIME STEP LENGTH', 1P, 5G12.5)
-    WRITE (IOUT, 202) PERSEC, PERMN, PERHR, PERDY, PERYR
-202 FORMAT(1X, 'STRESS PERIOD TIME', 1P, 5G12.5)
-    WRITE (IOUT, 203) TOTSEC, TOTMN, TOTHR, TOTDY, TOTYR
-203 FORMAT(1X, '        TOTAL TIME', 1P, 5G12.5,/)
-!C
-!C6------RETURN
-    RETURN
-  END subroutine tdis_ot
+    real(DP) :: cnv, delsec, totsec, persec, delmn, delhr, totmn, tothr, &
+                totdy, totyr, permn, perhr, perdy, peryr, deldy, delyr
+    ! -- format
+    character(len=*), parameter :: fmttmsmry = "(1X, ///9X, &
+      &'TIME SUMMARY AT END OF TIME STEP', I5,' IN STRESS PERIOD ', I4)"
+    character(len=*), parameter :: fmttmstpmsg = &
+      &"(21X, '     TIME STEP LENGTH =', G15.6 / &
+      & 21X, '   STRESS PERIOD TIME =', G15.6 / &
+      & 21X, 'TOTAL SIMULATION TIME =', G15.6)"
+    character(len=*), parameter :: fmttottmmsg = &
+      &"(19X, ' SECONDS     MINUTES      HOURS', 7X, &
+      &'DAYS        YEARS'/20X, 59('-'))"
+    character(len=*), parameter :: fmtdelttm = &
+      &"(1X, '  TIME STEP LENGTH', 1P, 5G12.5)"
+    character(len=*), parameter :: fmtpertm = &
+      &"(1X, 'STRESS PERIOD TIME', 1P, 5G12.5)"
+    character(len=*), parameter :: fmttottm = &
+      &"(1X, '        TOTAL TIME', 1P, 5G12.5,/)"
+    !
+    ! -- Write header message for the information that follows
+    write (iout, fmttmsmry) kstp, kper
+    !
+    ! -- Use time unit indicator to get factor to convert to seconds
+    cnv = DZERO
+    if (itmuni == 1) cnv = DONE
+    if (itmuni == 2) cnv = DSIXTY
+    if (itmuni == 3) cnv = DSECPERHR
+    if (itmuni == 4) cnv = DSECPERDY
+    if (itmuni == 5) cnv = DSECPERYR
+    !
+    ! -- If FACTOR=0 then time units are non-standard
+    if (cnv == DZERO) then
+      ! -- Print times in non-standard time units
+      write (iout, fmttmstpmsg) delt, pertim, totim
+    else
+      ! -- Calculate length of time step & elapsed time in seconds
+      delsec = cnv * delt
+      totsec = cnv * totim
+      persec = cnv * pertim
+      !
+      ! -- Calculate times in minutes, hours, days, and years
+      delmn = delsec / DSIXTY
+      delhr = delmn / DSIXTY
+      deldy = delhr / DHRPERDAY
+      delyr = deldy / DDYPERYR
+      totmn = totsec / DSIXTY
+      tothr = totmn / DSIXTY
+      totdy = tothr / DHRPERDAY
+      totyr = totdy / DDYPERYR
+      permn = persec / DSIXTY
+      perhr = permn / DSIXTY
+      perdy = perhr / DHRPERDAY
+      peryr = perdy / DDYPERYR
+      !
+      ! -- Print time step length and elapsed times in all time units
+      write (iout, fmttottmmsg)
+      write (iout, fmtdelttm) delsec, delmn, delhr, deldy, delyr
+      write (iout, fmtpertm) persec, permn, perhr, perdy, peryr
+      write (iout, fmttottm) totsec, totmn, tothr, totdy, totyr
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine tdis_ot
 
+  !> @brief Deallocate memory
+  !<
   subroutine tdis_da()
-! ******************************************************************************
-! tdis_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use MemoryManagerModule, only: mem_deallocate
     use AdaptiveTimeStepModule, only: ats_da
-! ------------------------------------------------------------------------------
+    !
     ! -- ats
     if (inats > 0) call ats_da()
     !
@@ -497,17 +468,13 @@ subroutine tdis_da()
     return
   end subroutine tdis_da
 
+  !> @brief Read the timing discretization options
+  !<
   subroutine tdis_read_options()
-! ******************************************************************************
-! tdis_read_options -- Read the options
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error
     use InputOutputModule, only: GetUnit, openfile
-    ! -- dummy
     ! -- local
     character(len=LINELENGTH) :: errmsg, keyword, fname
     integer(I4B) :: ierr
@@ -519,7 +486,6 @@ subroutine tdis_read_options()
     character(len=*), parameter :: fmtdatetime0 = &
       &"(4x,'SIMULATION STARTING DATE AND TIME IS ',A)"
     !data
-! ------------------------------------------------------------------------------
     !
     ! -- set variables
     itmuni = 0
@@ -599,17 +565,12 @@ subroutine tdis_read_options()
     return
   end subroutine tdis_read_options
 
+  !> @brief Read dimension NPER
+  !<
   subroutine tdis_allocate_scalars()
-! ******************************************************************************
-! tdis_read_dimensions -- Read dimension NPER
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     use ConstantsModule, only: DZERO
-! ------------------------------------------------------------------------------
     !
     ! -- memory manager variables
     call mem_allocate(nper, 'NPER', 'TDIS')
@@ -653,39 +614,30 @@ subroutine tdis_allocate_scalars()
     totalsimtime = DZERO
     datetime0 = ''
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine tdis_allocate_scalars
 
+  !> @brief Allocate tdis arrays
+  !<
   subroutine tdis_allocate_arrays()
-! ******************************************************************************
-! tdis_allocate_arrays -- Allocate tdis arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
-! ------------------------------------------------------------------------------
     !
     call mem_allocate(perlen, nper, 'PERLEN', 'TDIS')
     call mem_allocate(nstp, nper, 'NSTP', 'TDIS')
     call mem_allocate(tsmult, nper, 'TSMULT', 'TDIS')
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine tdis_allocate_arrays
 
+  !> @brief Read dimension NPER
+  !<
   subroutine tdis_read_dimensions()
-! ******************************************************************************
-! tdis_read_dimensions -- Read dimension NPER
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use ConstantsModule, only: LINELENGTH
     use SimModule, only: store_error
-    ! -- dummy
     ! -- local
     character(len=LINELENGTH) :: errmsg, keyword
     integer(I4B) :: ierr
@@ -693,8 +645,6 @@ subroutine tdis_read_dimensions()
     ! -- formats
     character(len=*), parameter :: fmtnper = &
                                    "(1X,I4,' STRESS PERIOD(S) IN SIMULATION')"
-    !data
-! ------------------------------------------------------------------------------
     !
     ! -- get DIMENSIONS block
     call parser%GetBlock('DIMENSIONS', isfound, ierr, &
@@ -729,16 +679,12 @@ subroutine tdis_read_dimensions()
     return
   end subroutine tdis_read_dimensions
 
+  !> @brief Read timing information
+  !<
   subroutine tdis_read_timing()
-! ******************************************************************************
-! tdis_read_timing -- Read timing information
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
     use ConstantsModule, only: LINELENGTH, DZERO
     use SimModule, only: store_error, count_errors
-    ! -- dummy
     ! -- local
     character(len=LINELENGTH) :: errmsg
     integer(I4B) :: ierr
@@ -750,7 +696,6 @@ subroutine tdis_read_timing()
        &'     MULTIPLIER FOR DELT',/1X,76('-'))"
     character(len=*), parameter :: fmtrow = &
                                    "(1X,I8,1PG21.7,I7,0PF25.3)"
-! ------------------------------------------------------------------------------
     !
     ! -- get PERIODDATA block
     call parser%GetBlock('PERIODDATA', isfound, ierr, &
@@ -788,16 +733,13 @@ subroutine tdis_read_timing()
     return
   end subroutine tdis_read_timing
 
+  !> @brief Check the tdis timing information
+  !!
+  !! Return back to tdis_read_timing if an error condition is found and let the
+  !! ustop routine be called there instead so the StoreErrorUnit routine can be
+  !! called to assign the correct file name.
+  !<
   subroutine check_tdis_timing(nper, perlen, nstp, tsmult)
-! ******************************************************************************
-! check_tdis_timing -- Check the tdis timing information.  Return back to
-!   tdis_read_timing if an error condition is found and let the ustop
-!   routine be called there instead so the StoreErrorUnit routine can be
-!   called to assign the correct file name.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH, DZERO, DONE
     use SimModule, only: store_error, count_errors
@@ -819,7 +761,6 @@ subroutine check_tdis_timing(nper, perlen, nstp, tsmult)
     character(len=*), parameter :: fmtdterror = &
       "('Time step length of ', G0, ' is too small in period ', I0, &
       &' and time step ', I0)"
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize
     tstart = DZERO
diff --git a/src/Utilities/ArrayHandlers.f90 b/src/Utilities/ArrayHandlers.f90
index 329917244d1..2b9c43bbf90 100644
--- a/src/Utilities/ArrayHandlers.f90
+++ b/src/Utilities/ArrayHandlers.f90
@@ -1,11 +1,11 @@
 module ArrayHandlersModule
 
   use KindModule, only: DP, I4B, LGP
+  use ErrorUtilModule, only: pstop
   use ConstantsModule, only: LINELENGTH, MAXCHARLEN, DZERO, DTEN
-  use SimVariablesModule, only: iout
-  use GenericUtilitiesModule, only: sim_message, stop_with_error
+  implicit none
   private
-  public :: ExpandArray, ExpandArrayWrapper, ExtendPtrArray
+  public :: ExpandArray, ExpandArray2D, ExpandArrayWrapper, ExtendPtrArray
   public :: ConcatArray
   public :: ifind
   public :: remove_character
@@ -19,10 +19,18 @@ module ArrayHandlersModule
     ! IMPORTANT: Do not use pointers to elements of arrays when using
     ! ExpandArray to increase the array size!  The locations of array
     ! elements in memory are changed when ExpandArray is invoked.
-    module procedure expand_integer, expand_double, &
-      expand_character !, expand_real
+    module procedure expand_integer, expand_double, expand_logical, &
+      expand_character
   end interface ExpandArray
 
+  interface ExpandArray2D
+    ! This interface is for use with ALLOCATABLE arrays.
+    ! IMPORTANT: Do not use pointers to elements of arrays when using
+    ! ExpandArray2D to increase the array size!  The locations of array
+    ! elements in memory are changed when ExpandArray2D is invoked.
+    module procedure expand_integer_2d, expand_double_2d
+  end interface ExpandArray2D
+
   interface ExtendPtrArray
     ! This interface is for use with POINTERS to arrays.
     module procedure extend_double, extend_integer, &
@@ -40,7 +48,6 @@ module ArrayHandlersModule
 contains
 
   subroutine expand_integer_wrapper(nsize, array, minvalue, loginc)
-    implicit none
     ! -- dummy
     integer(I4B), intent(in) :: nsize
     integer(I4B), allocatable, intent(inout) :: array(:)
@@ -92,307 +99,378 @@ subroutine expand_integer_wrapper(nsize, array, minvalue, loginc)
         array(n) = 0
       end do
     end if
-    !
-    ! -- return
-    return
+
   end subroutine expand_integer_wrapper
 
   ! -- Specific procedures that implement ExpandArray for allocatable arrays
 
   subroutine expand_integer(array, increment)
-    implicit none
     ! -- dummy
     integer(I4B), allocatable, intent(inout) :: array(:)
     integer(I4B), optional, intent(in) :: increment
     ! -- local
-    integer(I4B) :: inclocal, isize, newsize
-    integer(I4B), allocatable, dimension(:) :: array_temp
-    !
-    ! -- initialize
+    integer(I4B) :: inc, lb, n
+    integer(I4B), allocatable, dimension(:) :: temp
+
+    ! -- default to expanding by 1
     if (present(increment)) then
-      inclocal = increment
+      inc = increment
+      if (inc == 0) return
+      if (inc < 0) call pstop(1, "increment must be nonnegative")
     else
-      inclocal = 1
+      inc = 1
     end if
-    !
-    ! -- increase size of array by inclocal, retaining
-    !    contained data
+
+    ! -- expand array to the requested size, keeping
+    !    existing items and the existing lower bound,
+    !    or allocate the array if still unallocated
     if (allocated(array)) then
-      isize = size(array)
-      newsize = isize + inclocal
-      allocate (array_temp(newsize))
-      array_temp(1:isize) = array
+      lb = lbound(array, 1)
+      n = size(array)
+      allocate (temp(lb:(lb + n + inc - 1)))
+      temp(lb:(lb + n - 1)) = array
       deallocate (array)
-      call move_alloc(array_temp, array)
+      call move_alloc(temp, array)
     else
-      allocate (array(inclocal))
+      allocate (array(inc))
     end if
-    !
-    return
   end subroutine expand_integer
 
   subroutine expand_double(array, increment)
-    implicit none
     ! -- dummy
     real(DP), allocatable, intent(inout) :: array(:)
     integer(I4B), optional, intent(in) :: increment
     ! -- local
-    integer(I4B) :: inclocal, isize, newsize
-    real(DP), allocatable, dimension(:) :: array_temp
-    !
-    ! -- initialize
+    integer(I4B) :: inc, lb, n
+    real(DP), allocatable, dimension(:) :: temp
+
+    ! -- default to expanding by 1
     if (present(increment)) then
-      inclocal = increment
+      inc = increment
+      if (inc == 0) return
+      if (inc < 0) call pstop(1, "increment must be nonnegative")
     else
-      inclocal = 1
+      inc = 1
     end if
-    !
-    ! -- increase size of array by inclocal, retaining
-    !    contained data
+
+    ! -- expand array to the requested size, keeping
+    !    existing items and the existing lower bound,
+    !    or allocate the array if still unallocated
     if (allocated(array)) then
-      isize = size(array)
-      newsize = isize + inclocal
-      allocate (array_temp(newsize))
-      array_temp(1:isize) = array
+      lb = lbound(array, 1)
+      n = size(array)
+      allocate (temp(lb:(lb + n + inc - 1)))
+      temp(lb:(lb + n - 1)) = array
       deallocate (array)
-      call move_alloc(array_temp, array)
+      call move_alloc(temp, array)
     else
-      allocate (array(inclocal))
+      allocate (array(inc))
     end if
-    !
-    return
+
   end subroutine expand_double
 
+  subroutine expand_logical(array, increment)
+    ! -- dummy
+    logical(LGP), allocatable, intent(inout) :: array(:)
+    integer(I4B), optional, intent(in) :: increment
+    ! -- local
+    integer(I4B) :: inc, lb, n
+    logical(LGP), allocatable, dimension(:) :: temp
+
+    ! -- default to expanding by 1
+    if (present(increment)) then
+      inc = increment
+      if (inc == 0) return
+      if (inc < 0) call pstop(1, "increment must be nonnegative")
+    else
+      inc = 1
+    end if
+
+    ! -- expand array to the requested size, keeping
+    !    existing items and the existing lower bound,
+    !    or allocate the array if still unallocated
+    if (allocated(array)) then
+      lb = lbound(array, 1)
+      n = size(array)
+      allocate (temp(lb:(lb + n + inc - 1)))
+      temp(lb:(lb + n - 1)) = array
+      deallocate (array)
+      call move_alloc(temp, array)
+    else
+      allocate (array(inc))
+    end if
+
+  end subroutine expand_logical
+
   subroutine expand_character(array, increment)
-    implicit none
     ! -- dummy
     character(len=*), allocatable, intent(inout) :: array(:)
     integer(I4B), optional, intent(in) :: increment
     ! -- local
-    character(len=LINELENGTH) :: line
-    character(len=MAXCHARLEN), allocatable, dimension(:) :: array_temp
-    integer(I4B) :: i, inclocal, isize, lenc, newsize
-    ! -- format
-    character(len=*), parameter :: stdfmt = "(/,'ERROR REPORT:',/,1x,a)"
-    !
+    character(len=MAXCHARLEN), allocatable, dimension(:) :: temp
+    integer(I4B) :: i, inc, nold, nnew, lenc
+
     ! -- check character length
     lenc = len(array)
-    if (lenc > MAXCHARLEN) then
-      write (line, '(a)') 'Error in ArrayHandlersModule: '// &
-        'Need to increase MAXCHARLEN'
-      call sim_message(line, iunit=iout, fmt=stdfmt)
-      call sim_message(line, fmt=stdfmt)
-      !
-      ! -- stop message
-      write (line, '(a)') 'Stopping...'
-      call sim_message(line, iunit=iout)
-      call sim_message(line)
-      call stop_with_error(138)
-    end if
-    !
-    ! -- initialize
+    if (lenc > MAXCHARLEN) &
+      call pstop(138, 'Error in ArrayHandlersModule: '// &
+                 'Need to increase MAXCHARLEN. Stopping...')
+
+    ! -- default to expanding by 1
     if (present(increment)) then
-      inclocal = increment
+      inc = increment
+      if (inc == 0) return
+      if (inc < 0) call pstop(1, "increment must be nonnegative")
     else
-      inclocal = 1
+      inc = 1
     end if
-    !
-    ! -- increase size of array by inclocal, retaining
-    !    contained data
+
+    ! -- expand array to the requested size, keeping
+    !    existing items, or allocate if still needed
     ! [Ned TODO: may be able to use mold here, e.g.:
     !       allocate(values(num), mold=proto)]
     if (allocated(array)) then
-      isize = size(array)
-      newsize = isize + inclocal
-      allocate (array_temp(isize))
-      do i = 1, isize
-        array_temp(i) = array(i)
+      nold = size(array)
+      nnew = nold + inc
+      allocate (temp(nold))
+      do i = 1, nold
+        temp(i) = array(i)
       end do
       deallocate (array)
-      allocate (array(newsize))
-      do i = 1, isize
-        array(i) = array_temp(i)
+      allocate (array(nnew))
+      do i = 1, nold
+        array(i) = temp(i)
       end do
-      do i = isize + 1, newsize
+      do i = nold + 1, nnew
         array(i) = ''
       end do
-      deallocate (array_temp)
+      deallocate (temp)
     else
-      allocate (array(inclocal))
+      allocate (array(inc))
     end if
-    !
-    return
+
   end subroutine expand_character
 
+  ! -- Specific procedures that implement ExtendArray2D
+
+  subroutine expand_integer_2d(array, increment1, increment2)
+    ! -- dummy
+    integer(I4B), allocatable, intent(inout) :: array(:, :)
+    integer(I4B), optional, intent(in) :: increment1
+    integer(I4B), optional, intent(in) :: increment2
+    ! -- local
+    integer(I4B) :: inc1, inc2, lb1, lb2, n1, n2
+    integer(I4B), allocatable, dimension(:, :) :: temp
+
+    ! -- default to expanding both dimensions by 1
+    if (present(increment1)) then
+      inc1 = increment1
+    else
+      inc1 = 1
+    end if
+    if (present(increment2)) then
+      inc2 = increment2
+    else
+      inc2 = 1
+    end if
+    if (inc1 == 0 .and. inc2 == 0) return
+    if (inc1 < 0 .or. inc2 < 0) &
+      call pstop(1, "increments must be nonnegative")
+
+    ! -- expand array to the requested size, keeping
+    !    existing items and the existing lower bound,
+    !    or allocate the array if still unallocated
+    if (allocated(array)) then
+      lb1 = lbound(array, 1)
+      lb2 = lbound(array, 2)
+      n1 = size(array, 1)
+      n2 = size(array, 2)
+      allocate (temp( &
+                lb1:(lb1 + n1 + inc1 - 1), &
+                lb2:(lb2 + n2 + inc2 - 1)))
+      temp( &
+        lb1:(lb1 + n1 - 1), &
+        lb2:(lb2 + n2 - 1)) = array
+      deallocate (array)
+      call move_alloc(temp, array)
+    else
+      allocate (array(inc1, inc2))
+    end if
+
+  end subroutine expand_integer_2d
+
+  subroutine expand_double_2d(array, increment1, increment2)
+    ! -- dummy
+    real(DP), allocatable, intent(inout) :: array(:, :)
+    integer(I4B), optional, intent(in) :: increment1
+    integer(I4B), optional, intent(in) :: increment2
+    ! -- local
+    integer(I4B) :: inc1, inc2, lb1, lb2, n1, n2
+    real(DP), allocatable, dimension(:, :) :: temp
+
+    ! -- default to expanding both dimensions by 1
+    if (present(increment1)) then
+      inc1 = increment1
+    else
+      inc1 = 1
+    end if
+    if (present(increment2)) then
+      inc2 = increment2
+    else
+      inc2 = 1
+    end if
+    if (inc1 == 0 .and. inc2 == 0) return
+    if (inc1 < 0 .or. inc2 < 0) &
+      call pstop(1, "increments must be nonnegative")
+
+    ! -- expand array to the requested size, keeping
+    !    existing items and the existing lower bound,
+    !    or allocate the array if still unallocated
+    if (allocated(array)) then
+      lb1 = lbound(array, 1)
+      lb2 = lbound(array, 2)
+      n1 = size(array, 1)
+      n2 = size(array, 2)
+      allocate (temp( &
+                lb1:(lb1 + n1 + inc1 - 1), &
+                lb2:(lb2 + n2 + inc2 - 1)))
+      temp( &
+        lb1:(lb1 + n1 - 1), &
+        lb2:(lb2 + n2 - 1)) = array
+      deallocate (array)
+      call move_alloc(temp, array)
+    else
+      allocate (array(inc1, inc2))
+    end if
+
+  end subroutine expand_double_2d
+
   ! -- Specific procedures that implement ExtendPtrArray for pointer arrays
 
   subroutine extend_double(array, increment)
-    implicit none
     ! -- dummy
     real(DP), dimension(:), pointer, contiguous, intent(inout) :: array
     integer(I4B), optional, intent(in) :: increment
     ! -- local
-    character(len=LINELENGTH) :: line
     character(len=100) :: ermsg
-    integer(I4B) :: i, inclocal, isize, istat, newsize
-    real(DP), dimension(:), pointer, contiguous :: array_temp => null()
-    ! -- format
-    character(len=*), parameter :: stdfmt = "(/,'ERROR REPORT:',/,1x,a)"
-    !
-    ! -- initialize
+    integer(I4B) :: i, inc, lb, n, istat
+    real(DP), dimension(:), pointer, contiguous :: temp => null()
+
+    ! -- default to expanding by 1
     if (present(increment)) then
-      inclocal = increment
+      inc = increment
+      if (inc == 0) return
+      if (inc < 0) call pstop(1, "increment must be nonnegative")
     else
-      inclocal = 1
+      inc = 1
     end if
-    !
-    ! -- increase size of array by inclocal, retaining
-    !    contained data
+
+    ! -- expand array to the requested size, keeping
+    !    existing items and the existing lower bound,
+    !    or allocate the array if still unallocated
     if (associated(array)) then
-      isize = size(array)
-      newsize = isize + inclocal
-      allocate (array_temp(newsize), stat=istat, errmsg=ermsg)
-      if (istat /= 0) goto 99
-      do i = 1, isize
-        array_temp(i) = array(i)
+      lb = lbound(array, 1)
+      n = size(array)
+      allocate (temp(lb:(lb + n + inc - 1)), stat=istat, errmsg=ermsg)
+      if (istat /= 0) &
+        call pstop(138, 'Error in ArrayHandlersModule, '// &
+                   'could not increase array size:'//ermsg)
+      do i = lb, lb + n - 1
+        temp(i) = array(i)
       end do
       deallocate (array)
-      array => array_temp
+      array => temp
     else
-      allocate (array(inclocal))
+      allocate (array(inc))
     end if
-    !
-    ! -- normal return
-    return
-    !
-    ! -- Error reporting
-99  continue
-
-    write (line, '(a)') 'Error in ArrayHandlersModule: '// &
-      'Could not increase array size'
-    call sim_message(line, iunit=iout, fmt=stdfmt)
-    call sim_message(line, fmt=stdfmt)
-    !
-    ! -- error message
-    call sim_message(ermsg, iunit=iout)
-    call sim_message(ermsg)
-    !
-    ! -- stop message
-    write (line, '(a)') 'Stopping...'
-    call sim_message(line, iunit=iout)
-    call sim_message(line)
-    call stop_with_error(138)
 
   end subroutine extend_double
 
   subroutine extend_integer(array, increment)
-    implicit none
     ! -- dummy
     integer(I4B), dimension(:), pointer, contiguous, intent(inout) :: array
     integer(I4B), optional, intent(in) :: increment
     ! -- local
-    character(len=LINELENGTH) :: line
     character(len=100) :: ermsg
-    integer(I4B) :: i, inclocal, isize, istat, newsize
-    integer(I4B), dimension(:), pointer, contiguous :: array_temp => null()
-    ! -- format
-    character(len=*), parameter :: stdfmt = "(/,'ERROR REPORT:',/,1x,a)"
-    !
-    ! -- initialize
+    integer(I4B) :: i, inc, lb, n, istat
+    integer(I4B), dimension(:), pointer, contiguous :: temp => null()
+
+    ! -- default to expanding by 1
     if (present(increment)) then
-      inclocal = increment
+      inc = increment
+      if (inc == 0) return
+      if (inc < 0) call pstop(1, "increment must be nonnegative")
     else
-      inclocal = 1
+      inc = 1
     end if
-    !
-    ! -- increase size of array by inclocal, retaining
-    !    contained data
+
+    ! -- expand array to the requested size, keeping
+    !    existing items and the existing lower bound,
+    !    or allocate the array if still unallocated
     if (associated(array)) then
-      isize = size(array)
-      newsize = isize + inclocal
-      allocate (array_temp(newsize), stat=istat, errmsg=ermsg)
-      if (istat /= 0) goto 99
-      do i = 1, isize
-        array_temp(i) = array(i)
+      lb = lbound(array, 1)
+      n = size(array)
+      allocate (temp(lb:(lb + n + inc - 1)), stat=istat, errmsg=ermsg)
+      if (istat /= 0) &
+        call pstop(138, 'Error in ArrayHandlersModule, '// &
+                   'could not increase array size:'//ermsg)
+      do i = lb, lb + n - 1
+        temp(i) = array(i)
       end do
       deallocate (array)
-      array => array_temp
+      array => temp
     else
-      allocate (array(inclocal))
+      allocate (array(inc))
     end if
-    !
-    ! -- normal return
-    return
-    !
-    ! -- Error reporting
-99  continue
-
-    write (line, '(a)') 'Error in ArrayHandlersModule: '// &
-      'Could not increase array size'
-    call sim_message(line, iunit=iout, fmt=stdfmt)
-    call sim_message(line, fmt=stdfmt)
-    !
-    ! -- error message
-    call sim_message(ermsg, iunit=iout)
-    call sim_message(ermsg)
-    !
-    ! -- stop message
-    write (line, '(a)') 'Stopping...'
-    call sim_message(line, iunit=iout)
-    call sim_message(line)
-    call stop_with_error(138)
 
   end subroutine extend_integer
 
-  !> @brief Grows or allocated the array with the passed increment,
-  !< the old value of the array pointer is rendered invalid
   subroutine extend_string(array, increment)
+    ! -- dummy
     character(len=*), dimension(:), pointer, contiguous :: array
     integer(I4B), optional :: increment
-    ! local
-    integer(I4B) :: inc_local
-    integer(I4B) :: i, old_size, new_size
-    character(len=len(array)), dimension(:), pointer, contiguous :: temp_array
+    ! -- local
+    integer(I4B) :: inc, i, n
+    character(len=len(array)), dimension(:), pointer, contiguous :: temp
 
     if (present(increment)) then
-      inc_local = increment
+      inc = increment
+      if (inc == 0) return
+      if (inc < 0) call pstop(1, "increment must be nonnegative")
     else
-      inc_local = 1
+      inc = 1
     end if
 
     if (associated(array)) then
-      old_size = size(array)
-      new_size = old_size + inc_local
-      temp_array => array
-      allocate (array(new_size))
-      do i = 1, old_size
-        array(i) = temp_array(i)
+      n = size(array)
+      temp => array
+      allocate (array(n + inc))
+      do i = 1, n
+        array(i) = temp(i)
       end do
-      deallocate (temp_array)
+      deallocate (temp)
     else
-      allocate (array(inc_local))
+      allocate (array(inc))
     end if
 
   end subroutine extend_string
 
+  !> @brief Concatenate integer arrays.
   subroutine concat_integer(array, array_to_add)
     integer(I4B), dimension(:), pointer, contiguous :: array
     integer(I4B), dimension(:), pointer, contiguous :: array_to_add
     ! local
-    integer(I4B) :: i, old_size
+    integer(I4B) :: i, n
 
-    old_size = size(array)
+    n = size(array)
     call ExtendPtrArray(array, increment=size(array_to_add))
     do i = 1, size(array_to_add)
-      array(old_size + i) = array_to_add(i)
+      array(n + i) = array_to_add(i)
     end do
-
   end subroutine concat_integer
 
+  !> @brief Find the 1st array element containing str, or -1 if not found.
   function ifind_character(array, str)
-    ! -- Find the first array element containing str
-    ! -- Return -1 if not found.
-    implicit none
     ! -- return
     integer(I4B) :: ifind_character
     ! -- dummy
@@ -400,6 +478,7 @@ function ifind_character(array, str)
     character(len=*) :: str
     ! -- local
     integer(I4B) :: i
+
     ifind_character = -1
     findloop: do i = 1, size(array)
       if (array(i) == str) then
@@ -407,13 +486,10 @@ function ifind_character(array, str)
         exit findloop
       end if
     end do findloop
-    return
   end function ifind_character
 
+  !> @brief Find the first element containing str, or -1 if not found.
   function ifind_integer(iarray, ival)
-    ! -- Find the first array element containing str
-    ! -- Return -1 if not found.
-    implicit none
     ! -- return
     integer(I4B) :: ifind_integer
     ! -- dummy
@@ -421,6 +497,7 @@ function ifind_integer(iarray, ival)
     integer(I4B) :: ival
     ! -- local
     integer(I4B) :: i
+
     ifind_integer = -1
     findloop: do i = 1, size(iarray)
       if (iarray(i) == ival) then
@@ -428,60 +505,44 @@ function ifind_integer(iarray, ival)
         exit findloop
       end if
     end do findloop
-    return
   end function ifind_integer
 
+  !> @brief Remove the element at ipos from the array.
   subroutine remove_character(array, ipos)
-    !remove the ipos position from array
-    implicit none
     ! -- dummy
     character(len=*), allocatable, intent(inout) :: array(:)
     integer(I4B), intent(in) :: ipos
     ! -- local
-    character(len=LINELENGTH) :: line
-    character(len=MAXCHARLEN), allocatable, dimension(:) :: array_temp
-    integer(I4B) :: i, isize, lenc, newsize, inew
-    ! -- format
-    character(len=*), parameter :: stdfmt = "(/,'ERROR REPORT:',/,1x,a)"
-    !
+    character(len=MAXCHARLEN), allocatable, dimension(:) :: temp
+    integer(I4B) :: i, inew, n
+
     ! -- check character length
-    lenc = len(array)
-    if (lenc > MAXCHARLEN) then
+    if (len(array) > MAXCHARLEN) &
+      call pstop(138, 'Error in ArrayHandlersModule: '// &
+                 'Need to increase MAXCHARLEN. Stopping...')
 
-      write (line, '(a)') 'Error in ArrayHandlersModule: '// &
-        'Need to increase MAXCHARLEN'
-      call sim_message(line, iunit=iout, fmt=stdfmt)
-      call sim_message(line, fmt=stdfmt)
-      !
-      ! -- stop message
-      write (line, '(a)') 'Stopping...'
-      call sim_message(line, iunit=iout)
-      call sim_message(line)
-      call stop_with_error(138)
-    end if
-    !
-    ! -- calculate sizes
-    isize = size(array)
-    newsize = isize - 1
-    !
-    ! -- copy array to array_temp
-    allocate (array_temp(isize))
-    do i = 1, isize
-      array_temp(i) = array(i)
+    ! -- calculate size
+    n = size(array)
+
+    ! -- copy array to temp
+    allocate (temp(n))
+    do i = 1, n
+      temp(i) = array(i)
     end do
-    !
+
+    ! -- de/reallocate and copy back to array,
+    !    omitting the specified element
     deallocate (array)
-    allocate (array(newsize))
+    allocate (array(n - 1))
     inew = 1
-    do i = 1, isize
+    do i = 1, n
       if (i /= ipos) then
-        array(inew) = array_temp(i)
+        array(inew) = temp(i)
         inew = inew + 1
       end if
     end do
-    deallocate (array_temp)
-    !
-    return
+    deallocate (temp)
+
   end subroutine remove_character
 
 end module ArrayHandlersModule
diff --git a/src/Utilities/ArrayReaders.f90 b/src/Utilities/ArrayReaders.f90
index 537e0d47f50..32e49130faa 100644
--- a/src/Utilities/ArrayReaders.f90
+++ b/src/Utilities/ArrayReaders.f90
@@ -6,9 +6,10 @@ module ArrayReadersModule
   use InputOutputModule, only: openfile, u9rdcom, urword, ucolno, ulaprw, &
                                BuildFixedFormat, BuildFloatFormat, &
                                BuildIntFormat
-  use KindModule, only: DP, I4B
+  use KindModule, only: DP, I4B, LGP
   use OpenSpecModule, only: ACCESS, FORM
   use SimModule, only: store_error, store_error_unit
+  use SimVariablesModule, only: errmsg
 
   implicit none
 
@@ -57,13 +58,14 @@ subroutine read_array_int1d(iu, iarr, aname, ndim, jj, iout, k)
     integer(I4B), intent(in) :: ndim ! dis%ndim
     integer(I4B), intent(in) :: k ! layer number; 0 to not print
     ! -- local
+    logical(LGP) :: isok
     integer(I4B) :: iclose, iconst, iprn, j, locat, ncpl, ndig
     integer(I4B) :: nval, nvalt
     logical :: prowcolnum
     character(len=100) :: prfmt
     integer(I4B) :: istat
     character(len=30) :: arrname
-    character(len=MAXCHARLEN) :: ermsg, ermsgr
+    character(len=MAXCHARLEN) :: ermsgr
     ! -- formats
 2   format(/, 1x, a, ' = ', i0, ' FOR LAYER ', i0)
 3   format(/, 1x, a, ' = ', i0)
@@ -89,9 +91,9 @@ subroutine read_array_int1d(iu, iarr, aname, ndim, jj, iout, k)
       read (locat, *, iostat=istat, iomsg=ermsgr) (iarr(j), j=1, jj)
       if (istat /= 0) then
         arrname = adjustl(aname)
-        ermsg = 'Error reading data for array: '//trim(arrname)
-        call store_error(ermsg)
-        call store_error(ermsgr)
+        errmsg = "Error reading data for array '"//trim(arrname)// &
+                 "'. "//trim(adjustl(ermsgr))
+        call store_error(errmsg)
         call store_error_unit(locat)
       end if
       do j = 1, jj
@@ -106,13 +108,15 @@ subroutine read_array_int1d(iu, iarr, aname, ndim, jj, iout, k)
       nvalt = 0
       do
         call read_binary_header(locat, iout, aname, nval)
+        isok = check_binary_size(nval, nvalt, size(iarr), aname, locat)
+        if (isok .EQV. .FALSE.) exit
         read (locat, iostat=istat, iomsg=ermsgr) &
           (iarr(j), j=nvalt + 1, nvalt + nval)
         if (istat /= 0) then
           arrname = adjustl(aname)
-          ermsg = 'Error reading data for array: '//trim(arrname)
-          call store_error(ermsg)
-          call store_error(ermsgr)
+          errmsg = "Error reading data for array '"//trim(arrname)// &
+                   "'. "//trim(adjustl(ermsgr))
+          call store_error(errmsg)
           call store_error_unit(locat)
         end if
         nvalt = nvalt + nval
@@ -150,13 +154,14 @@ subroutine read_array_int2d(iu, iarr, aname, ndim, jj, ii, iout, k)
     integer(I4B), intent(in) :: ndim ! dis%ndim
     integer(I4B), intent(in) :: k ! layer number; 0 to not print
     ! -- local
+    logical(LGP) :: isok
     integer(I4B) :: i, iclose, iconst, iprn, j, locat, ncpl, ndig
     integer(I4B) :: nval
     logical :: prowcolnum
     character(len=100) :: prfmt
     integer(I4B) :: istat
     character(len=30) :: arrname
-    character(len=MAXCHARLEN) :: ermsg, ermsgr
+    character(len=MAXCHARLEN) :: ermsgr
     ! -- formats
 2   format(/, 1x, a, ' = ', i0, ' FOR LAYER ', i0)
 3   format(/, 1x, a, ' = ', i0)
@@ -185,9 +190,9 @@ subroutine read_array_int2d(iu, iarr, aname, ndim, jj, ii, iout, k)
         read (locat, *, iostat=istat, iomsg=ermsgr) (iarr(j, i), j=1, jj)
         if (istat /= 0) then
           arrname = adjustl(aname)
-          ermsg = 'Error reading data for array: '//trim(arrname)
-          call store_error(ermsg)
-          call store_error(ermsgr)
+          errmsg = "Error reading data for array '"//trim(arrname)// &
+                   "'. "//trim(adjustl(ermsgr))
+          call store_error(errmsg)
           call store_error_unit(locat)
         end if
         do j = 1, jj
@@ -201,19 +206,22 @@ subroutine read_array_int2d(iu, iarr, aname, ndim, jj, ii, iout, k)
       ! -- Read data as binary
       locat = -locat
       call read_binary_header(locat, iout, aname, nval)
-      do i = 1, ii
-        read (locat, iostat=istat, iomsg=ermsgr) (iarr(j, i), j=1, jj)
-        if (istat /= 0) then
-          arrname = adjustl(aname)
-          ermsg = 'Error reading data for array: '//trim(arrname)
-          call store_error(ermsg)
-          call store_error(ermsgr)
-          call store_error_unit(locat)
-        end if
-        do j = 1, jj
-          iarr(j, i) = iarr(j, i) * iconst
+      isok = check_binary_size(nval, 0, size(iarr), aname, locat)
+      if (isok) then
+        do i = 1, ii
+          read (locat, iostat=istat, iomsg=ermsgr) (iarr(j, i), j=1, jj)
+          if (istat /= 0) then
+            arrname = adjustl(aname)
+            errmsg = "Error reading data for array '"//trim(arrname)// &
+                     "'. "//trim(adjustl(ermsgr))
+            call store_error(errmsg)
+            call store_error_unit(locat)
+          end if
+          do j = 1, jj
+            iarr(j, i) = iarr(j, i) * iconst
+          end do
         end do
-      end do
+      end if
       if (iclose == 1) then
         close (locat)
       end if
@@ -310,6 +318,7 @@ subroutine read_array_dbl1d(iu, darr, aname, ndim, jj, iout, k)
     integer(I4B), intent(in) :: ndim ! dis%ndim
     integer(I4B), intent(in) :: k ! layer number; 0 to not print
     ! -- local
+    logical(LGP) :: isok
     integer(I4B) :: j, iclose, iprn, locat, ncpl, ndig
     real(DP) :: cnstnt
     logical :: prowcolnum
@@ -317,7 +326,7 @@ subroutine read_array_dbl1d(iu, darr, aname, ndim, jj, iout, k)
     integer(I4B) :: istat
     integer(I4B) :: nvalt, nval
     character(len=30) :: arrname
-    character(len=MAXCHARLEN) :: ermsg, ermsgr
+    character(len=MAXCHARLEN) :: ermsgr
     ! -- formats
 2   format(/, 1x, a, ' = ', g14.7, ' FOR LAYER ', i0)
 3   format(/, 1x, a, ' = ', g14.7)
@@ -343,9 +352,9 @@ subroutine read_array_dbl1d(iu, darr, aname, ndim, jj, iout, k)
       read (locat, *, iostat=istat, iomsg=ermsgr) (darr(j), j=1, jj)
       if (istat /= 0) then
         arrname = adjustl(aname)
-        ermsg = 'Error reading data for array: '//trim(arrname)
-        call store_error(ermsg)
-        call store_error(ermsgr)
+        errmsg = "Error reading data for array '"// &
+                 trim(adjustl(arrname))//"'. "//trim(adjustl(ermsgr))
+        call store_error(errmsg)
         call store_error_unit(locat)
       end if
       do j = 1, jj
@@ -360,13 +369,15 @@ subroutine read_array_dbl1d(iu, darr, aname, ndim, jj, iout, k)
       nvalt = 0
       do
         call read_binary_header(locat, iout, aname, nval)
+        isok = check_binary_size(nval, nvalt, size(darr), aname, locat)
+        if (isok .EQV. .FALSE.) exit
         read (locat, iostat=istat, iomsg=ermsgr) &
           (darr(j), j=nvalt + 1, nvalt + nval)
         if (istat /= 0) then
           arrname = adjustl(aname)
-          ermsg = 'Error reading data for array: '//trim(arrname)
-          call store_error(ermsg)
-          call store_error(ermsgr)
+          errmsg = "Error reading data for array '"// &
+                   trim(adjustl(arrname))//"'. "//trim(adjustl(ermsgr))
+          call store_error(errmsg)
           call store_error_unit(locat)
         end if
         nvalt = nvalt + nval
@@ -404,6 +415,7 @@ subroutine read_array_dbl2d(iu, darr, aname, ndim, jj, ii, iout, k)
     integer(I4B), intent(in) :: ndim ! dis%ndim
     integer(I4B), intent(in) :: k ! layer number; 0 to not print
     ! -- local
+    logical(LGP) :: isok
     integer(I4B) :: i, iclose, iprn, j, locat, ncpl, ndig
     integer(I4B) :: nval
     real(DP) :: cnstnt
@@ -411,7 +423,7 @@ subroutine read_array_dbl2d(iu, darr, aname, ndim, jj, ii, iout, k)
     character(len=100) :: prfmt
     integer(I4B) :: istat
     character(len=30) :: arrname
-    character(len=MAXCHARLEN) :: ermsg, ermsgr
+    character(len=MAXCHARLEN) :: ermsgr
     ! -- formats
 2   format(/, 1x, a, ' = ', g14.7, ' FOR LAYER ', i0)
 3   format(/, 1x, a, ' = ', g14.7)
@@ -440,9 +452,9 @@ subroutine read_array_dbl2d(iu, darr, aname, ndim, jj, ii, iout, k)
         read (locat, *, iostat=istat, iomsg=ermsgr) (darr(j, i), j=1, jj)
         if (istat /= 0) then
           arrname = adjustl(aname)
-          ermsg = 'Error reading data for array: '//trim(arrname)
-          call store_error(ermsg)
-          call store_error(ermsgr)
+          errmsg = "Error reading data for array '"// &
+                   trim(adjustl(arrname))//"'. "//trim(adjustl(ermsgr))
+          call store_error(errmsg)
           call store_error_unit(locat)
         end if
         do j = 1, jj
@@ -456,19 +468,22 @@ subroutine read_array_dbl2d(iu, darr, aname, ndim, jj, ii, iout, k)
       ! -- Read data as binary
       locat = -locat
       call read_binary_header(locat, iout, aname, nval)
-      do i = 1, ii
-        read (locat, iostat=istat, iomsg=ermsgr) (darr(j, i), j=1, jj)
-        if (istat /= 0) then
-          arrname = adjustl(aname)
-          ermsg = 'Error reading data for array: '//trim(arrname)
-          call store_error(ermsg)
-          call store_error(ermsgr)
-          call store_error_unit(locat)
-        end if
-        do j = 1, jj
-          darr(j, i) = darr(j, i) * cnstnt
+      isok = check_binary_size(nval, 0, size(darr), aname, locat)
+      if (isok) then
+        do i = 1, ii
+          read (locat, iostat=istat, iomsg=ermsgr) (darr(j, i), j=1, jj)
+          if (istat /= 0) then
+            arrname = adjustl(aname)
+            errmsg = "Error reading data for array '"// &
+                     trim(adjustl(arrname))//"'. "//trim(adjustl(ermsgr))
+            call store_error(errmsg)
+            call store_error_unit(locat)
+          end if
+          do j = 1, jj
+            darr(j, i) = darr(j, i) * cnstnt
+          end do
         end do
-      end do
+      end if
       if (iclose == 1) then
         close (locat)
       end if
@@ -659,6 +674,7 @@ subroutine read_control_dbl(iu, iout, aname, locat, cnstnt, &
   end subroutine read_control_dbl
 
   subroutine read_control_1(iu, iout, aname, locat, iclose, line, icol, fname)
+    use SimModule, only: ustop
     ! -- Read CONSTANT, INTERNAL, or OPEN/CLOSE from array control record.
     ! -- dummy
     integer(I4B), intent(in) :: iu
@@ -674,9 +690,9 @@ subroutine read_control_1(iu, iout, aname, locat, iclose, line, icol, fname)
     integer(I4B) :: istart, istop, n
     integer(I4B) :: ierr
     real(DP) :: r
-    character(len=MAXCHARLEN) :: ermsg
     !
-    ! -- Read array control record.
+    ! -- Read array control record.  Any future refactoring
+    !    should use the LongLineReader here instead of u9rdcom
     call u9rdcom(iu, iout, line, ierr)
     !
     iclose = 0
@@ -693,12 +709,10 @@ subroutine read_control_1(iu, iout, aname, locat, iclose, line, icol, fname)
       locat = -1
       iclose = 1
     else
-      write (ermsg, *) 'ERROR READING CONTROL RECORD FOR '// &
-        trim(adjustl(aname))
-      call store_error(ermsg)
-      call store_error(trim(adjustl(line)))
-      write (ermsg, *) 'Use CONSTANT, INTERNAL, or OPEN/CLOSE.'
-      call store_error(ermsg)
+      errmsg = 'READING CONTROL RECORD FOR '// &
+               trim(adjustl(aname))//"'. "// &
+               'Use CONSTANT, INTERNAL, or OPEN/CLOSE.'
+      call store_error(errmsg)
       call store_error_unit(iu)
     end if
     !
@@ -718,7 +732,6 @@ subroutine read_control_2(iu, iout, fname, line, icol, &
     integer(I4B) :: i, n, istart, istop, lenkey
     real(DP) :: r
     character(len=MAXCHARLEN) :: keyword
-    character(len=LENBIGLINE) :: ermsg
     logical :: binary
     !
     iprn = -1 ! Printing is turned off by default
@@ -734,9 +747,9 @@ subroutine read_control_2(iu, iout, fname, line, icol, &
         select case (keyword)
         case ('(BINARY)')
           if (iclose == 0) then
-            ermsg = '"(BINARY)" option for array input is valid only if'// &
-                    ' OPEN/CLOSE is also specified.'
-            call store_error(ermsg)
+            errmsg = '"(BINARY)" option for array input is valid only if'// &
+                     ' OPEN/CLOSE is also specified.'
+            call store_error(errmsg)
             call store_error_unit(iu)
           end if
           binary = .true.
@@ -747,9 +760,9 @@ subroutine read_control_2(iu, iout, fname, line, icol, &
         case ('')
           exit
         case default
-          ermsg = 'Invalid option found in array-control record: "' &
-                  //trim(keyword)//'"'
-          call store_error(ermsg)
+          errmsg = 'Invalid option found in array-control record: "' &
+                   //trim(keyword)//'"'
+          call store_error(errmsg)
           call store_error_unit(iu)
         end select
       end do
@@ -982,7 +995,6 @@ subroutine print_array_int(iarr, aname, iout, jj, ii, k, prfmt, &
     logical, intent(in) :: prowcolnum ! Print row & column numbers
     ! -- local
     integer(I4B) :: i, j
-    character(len=MAXCHARLEN) :: ermsg
     ! -- formats
 2   format(/, 1x, a, 1x, 'FOR LAYER ', i0)
 3   format(/, 1x, a)
@@ -1007,9 +1019,9 @@ subroutine print_array_int(iarr, aname, iout, jj, ii, k, prfmt, &
       end do
     else
       if (ii > 1) then
-        ermsg = 'Program error printing array '//trim(aname)// &
-                ': ii > 1 when prowcolnum is false.'
-        call store_error(ermsg, terminate=.TRUE.)
+        errmsg = 'Program error printing array '//trim(aname)// &
+                 ': ii > 1 when prowcolnum is false.'
+        call store_error(errmsg, terminate=.TRUE.)
       end if
       !
       ! -- Write array values, without row numbers
@@ -1031,7 +1043,6 @@ subroutine print_array_dbl(darr, aname, iout, jj, ii, k, prfmt, &
     logical, intent(in) :: prowcolnum ! Print row & column numbers
     ! -- local
     integer(I4B) :: i, j
-    character(len=MAXCHARLEN) :: ermsg
     ! -- formats
 2   format(/, 1x, a, 1x, 'FOR LAYER ', i0)
 3   format(/, 1x, a)
@@ -1056,9 +1067,9 @@ subroutine print_array_dbl(darr, aname, iout, jj, ii, k, prfmt, &
       end do
     else
       if (ii > 1) then
-        ermsg = 'Program error printing array '//trim(aname)// &
-                ': ii > 1 when prowcolnum is false.'
-        call store_error(ermsg, terminate=.TRUE.)
+        errmsg = 'Program error printing array '//trim(aname)// &
+                 ': ii > 1 when prowcolnum is false.'
+        call store_error(errmsg, terminate=.TRUE.)
       end if
       !
       ! -- Write array values, without row numbers
@@ -1079,7 +1090,7 @@ subroutine read_binary_header(locat, iout, arrname, nval)
     integer(I4B) :: kstp, kper, m1, m2, m3
     real(DP) :: pertim, totim
     character(len=16) :: text
-    character(len=MAXCHARLEN) :: ermsg, ermsgr
+    character(len=MAXCHARLEN) :: ermsgr
     character(len=*), parameter :: fmthdr = &
       "(/,1X,'HEADER FROM BINARY FILE HAS FOLLOWING ENTRIES',&
        &/,4X,'KSTP: ',I0,'  KPER: ',I0,&
@@ -1093,9 +1104,9 @@ subroutine read_binary_header(locat, iout, arrname, nval)
     !
     ! -- Check for errors
     if (istat /= 0) then
-      ermsg = 'Error reading data for array: '//adjustl(trim(arrname))
-      call store_error(ermsg)
-      call store_error(ermsgr)
+      errmsg = "Error reading data for array '"//adjustl(trim(arrname))// &
+               "'. "//trim(adjustl(ermsgr))
+      call store_error(errmsg)
       call store_error_unit(locat)
     end if
     !
@@ -1111,4 +1122,41 @@ subroutine read_binary_header(locat, iout, arrname, nval)
     return
   end subroutine read_binary_header
 
+  !> @ brief Check the binary data size
+  !!
+  !!  Check the size of the binary data that will be read
+  !!  relative to the unfilled elements in the array .
+  !!
+  !<
+  function check_binary_size(nval, nvalt, arrsize, aname, locat) result(isok)
+    ! -- dummy
+    integer(I4B), intent(in) :: nval !< number of array
+    integer(I4B), intent(in) :: nvalt !< current data index
+    integer(I4B), intent(in) :: arrsize !< size of the array
+    character(len=*), intent(in) :: aname !< name of array
+    integer(I4B), intent(in) :: locat !< binary file unit
+    !
+    ! -- local variables
+    logical(LGP) :: isok
+    !
+    ! -- initialize isok
+    isok = .TRUE.
+    !
+    if (nvalt + nval > arrsize) then
+      write (errmsg, '(a,i0,a,1x,a,1x,a,i0,a,1x,i0,3(1x,a))') &
+        'The size of the data array calculated from the binary header (', &
+        nval, ') will exceed the remainder of the', trim(adjustl(aname)), &
+        'data array (', arrsize, ') array by', nvalt + nval - arrsize, &
+        'elements. This is usually caused by incorrect assignment of', &
+        '(m1,m2,m3) in the binary header. See the mf6io.pdf document', &
+        'for information on assigning (m1,m2,m3).'
+      call store_error(errmsg)
+      call store_error_unit(locat)
+      isok = .FALSE.
+    end if
+    !
+    ! -- return
+    return
+  end function check_binary_size
+
 end module ArrayReadersModule
diff --git a/src/Utilities/BlockParser.f90 b/src/Utilities/BlockParser.f90
index 2cc5159db58..887955ff972 100644
--- a/src/Utilities/BlockParser.f90
+++ b/src/Utilities/BlockParser.f90
@@ -7,17 +7,18 @@
 module BlockParserModule
 
   use KindModule, only: DP, I4B
-  use ConstantsModule, only: LENHUGELINE, LINELENGTH, MAXCHARLEN
-  use VersionModule, only: IDEVELOPMODE
-  use InputOutputModule, only: uget_block, uget_any_block, uterminate_block, &
-                               u9rdcom, urword, upcase
+  use DevFeatureModule, only: dev_feature
+  use ConstantsModule, only: LENBIGLINE, LENHUGELINE, LINELENGTH, MAXCHARLEN
+  use InputOutputModule, only: urword, upcase, openfile, &
+                               io_getunit => GetUnit
   use SimModule, only: store_error, store_error_unit
   use SimVariablesModule, only: errmsg
+  use LongLineReaderModule, only: LongLineReaderType
 
   implicit none
 
   private
-  public :: BlockParserType
+  public :: BlockParserType, uget_block, uget_any_block, uterminate_block
 
   type :: BlockParserType
     integer(I4B), public :: iuactive !< flag indicating if a file unit is active, variable is not used internally
@@ -30,6 +31,7 @@ module BlockParserModule
     character(len=LINELENGTH), private :: blockNameFound !< block name found
     character(len=LENHUGELINE), private :: laststring !< last string read
     character(len=:), allocatable, private :: line !< current line
+    type(LongLineReaderType) :: line_reader
   contains
     procedure, public :: Initialize
     procedure, public :: Clear
@@ -155,8 +157,9 @@ subroutine GetBlock(this, blockName, isFound, ierr, supportOpenClose, &
     this%blockNameFound = ''
     !
     if (blockName == '*') then
-      call uget_any_block(this%inunit, this%iout, isFound, this%lloc, &
-                          this%line, blockNameFound, this%iuext)
+      call uget_any_block(this%line_reader, this%inunit, this%iout, &
+                          isFound, this%lloc, this%line, blockNameFound, &
+                          this%iuext)
       if (isFound) then
         this%blockNameFound = blockNameFound
         ierr = 0
@@ -164,7 +167,8 @@ subroutine GetBlock(this, blockName, isFound, ierr, supportOpenClose, &
         ierr = 1
       end if
     else
-      call uget_block(this%inunit, this%iout, this%blockName, ierr, isFound, &
+      call uget_block(this%line_reader, this%inunit, this%iout, &
+                      this%blockName, ierr, isFound, &
                       this%lloc, this%line, this%iuext, continueRead, &
                       supportOpenCloseLocal)
       if (isFound) this%blockNameFound = this%blockName
@@ -202,7 +206,7 @@ subroutine GetNextLine(this, endOfBlock)
     ! -- read next line
     loop1: do
       if (lineread) exit loop1
-      call u9rdcom(this%iuext, this%iout, this%line, ierr)
+      call this%line_reader%rdcom(this%iuext, this%iout, this%line, ierr)
       this%lloc = 1
       call urword(this%line, this%lloc, istart, istop, 0, ival, rval, &
                   this%iout, this%iuext)
@@ -562,29 +566,258 @@ function GetUnit(this) result(i)
     return
   end function GetUnit
 
-  !> @ brief Development option
+  !> @ brief Disable development option in release mode
   !!
-  !! Method that will cause the program to terminate with an error if the
-  !! IDEVELOPMODE flag is set to 1.  This is used to allow develop options
-  !! to be specified for development testing but not for the public release.
-  !! For the public release, IDEVELOPMODE is set to zero.
+  !! Terminate with an error if in release mode (IDEVELOPMODE = 0). Enables
+  !! options for development and testing while disabling for public release.
   !!
   !<
   subroutine DevOpt(this)
     ! -- dummy variables
-    class(BlockParserType), intent(inout) :: this !< BlockParserType object
+    class(BlockParserType), intent(inout) :: this
     !
-    ! -- If release mode (not develop mode), then option not available.
-    !    Terminate with an error.
-    if (IDEVELOPMODE == 0) then
-      errmsg = "Invalid keyword '"//trim(this%laststring)// &
-               "' detected in block '"//trim(this%blockname)//"'."
-      call store_error(errmsg)
-      call this%StoreErrorUnit()
-    end if
+    errmsg = "Invalid keyword '"//trim(this%laststring)// &
+             "' detected in block '"//trim(this%blockname)//"'."
+    call dev_feature(errmsg, this%iuext)
     !
-    ! -- Return
     return
   end subroutine DevOpt
 
+  ! -- static methods previously in InputOutput
+  !> @brief Find a block in a file
+  !!
+  !! Subroutine to read from a file until the tag (ctag) for a block is
+  !! is found. Return isfound with true, if found.
+  !!
+  !<
+  subroutine uget_block(line_reader, iin, iout, ctag, ierr, isfound, &
+                        lloc, line, iuext, blockRequired, supportopenclose)
+    implicit none
+    ! -- dummy variables
+    type(LongLineReaderType), intent(inout) :: line_reader
+    integer(I4B), intent(in) :: iin !< file unit
+    integer(I4B), intent(in) :: iout !< output listing file unit
+    character(len=*), intent(in) :: ctag !< block tag
+    integer(I4B), intent(out) :: ierr !< error
+    logical, intent(inout) :: isfound !< boolean indicating if the block was found
+    integer(I4B), intent(inout) :: lloc !< position in line
+    character(len=:), allocatable, intent(inout) :: line !< line
+    integer(I4B), intent(inout) :: iuext !< external file unit number
+    logical, optional, intent(in) :: blockRequired !< boolean indicating if the block is required
+    logical, optional, intent(in) :: supportopenclose !< boolean indicating if the block supports open/close
+    ! -- local variables
+    integer(I4B) :: istart
+    integer(I4B) :: istop
+    integer(I4B) :: ival
+    integer(I4B) :: lloc2
+    real(DP) :: rval
+    character(len=:), allocatable :: line2
+    character(len=LINELENGTH) :: fname
+    character(len=MAXCHARLEN) :: ermsg
+    logical :: supportoc, blockRequiredLocal
+    !
+    ! -- code
+    if (present(blockRequired)) then
+      blockRequiredLocal = blockRequired
+    else
+      blockRequiredLocal = .true.
+    end if
+    supportoc = .false.
+    if (present(supportopenclose)) then
+      supportoc = supportopenclose
+    end if
+    iuext = iin
+    isfound = .false.
+    mainloop: do
+      lloc = 1
+      call line_reader%rdcom(iin, iout, line, ierr)
+      if (ierr < 0) then
+        if (blockRequiredLocal) then
+          ermsg = 'Required block "'//trim(ctag)// &
+                  '" not found.  Found end of file instead.'
+          call store_error(ermsg)
+          call store_error_unit(iuext)
+        end if
+        ! block not found so exit
+        exit
+      end if
+      call urword(line, lloc, istart, istop, 1, ival, rval, iin, iout)
+      if (line(istart:istop) == 'BEGIN') then
+        call urword(line, lloc, istart, istop, 1, ival, rval, iin, iout)
+        if (line(istart:istop) == ctag) then
+          isfound = .true.
+          if (supportoc) then
+            ! Look for OPEN/CLOSE on 1st line after line starting with BEGIN
+            call line_reader%rdcom(iin, iout, line2, ierr)
+            if (ierr < 0) exit
+            lloc2 = 1
+            call urword(line2, lloc2, istart, istop, 1, ival, rval, iin, iout)
+            if (line2(istart:istop) == 'OPEN/CLOSE') then
+              ! -- Get filename and preserve case
+              call urword(line2, lloc2, istart, istop, 0, ival, rval, iin, iout)
+              fname = line2(istart:istop)
+              ! If line contains '(BINARY)' or 'SFAC', handle this block elsewhere
+              chk: do
+                call urword(line2, lloc2, istart, istop, 1, ival, rval, iin, iout)
+                if (line2(istart:istop) == '') exit chk
+                if (line2(istart:istop) == '(BINARY)' .or. &
+                    line2(istart:istop) == 'SFAC') then
+                  call line_reader%bkspc(iin)
+                  exit mainloop
+                end if
+              end do chk
+              iuext = io_getunit()
+              call openfile(iuext, iout, fname, 'OPEN/CLOSE')
+            else
+              call line_reader%bkspc(iin)
+            end if
+          end if
+        else
+          if (blockRequiredLocal) then
+            ermsg = 'Error: Required block "'//trim(ctag)// &
+                    '" not found. Found block "'//line(istart:istop)// &
+                    '" instead.'
+            call store_error(ermsg)
+            call store_error_unit(iuext)
+          else
+            call line_reader%bkspc(iin)
+          end if
+        end if
+        exit mainloop
+      else if (line(istart:istop) == 'END') then
+        call urword(line, lloc, istart, istop, 1, ival, rval, iin, iout)
+        if (line(istart:istop) == ctag) then
+          ermsg = 'Error: Looking for BEGIN '//trim(ctag)// &
+                  ' but found END '//line(istart:istop)// &
+                  ' instead.'
+          call store_error(ermsg)
+          call store_error_unit(iuext)
+        end if
+      end if
+    end do mainloop
+    !
+    ! -- return
+    return
+  end subroutine uget_block
+
+  !> @brief Find the next block in a file
+  !!
+  !! Subroutine to read from a file until next block is found.
+  !! Return isfound with true, if found, and return the block name.
+  !!
+  !<
+  subroutine uget_any_block(line_reader, iin, iout, isfound, &
+                            lloc, line, ctagfound, iuext)
+    implicit none
+    ! -- dummy variables
+    type(LongLineReaderType), intent(inout) :: line_reader
+    integer(I4B), intent(in) :: iin !< file unit number
+    integer(I4B), intent(in) :: iout !< output listing file unit
+    logical, intent(inout) :: isfound !< boolean indicating if a block was found
+    integer(I4B), intent(inout) :: lloc !< position in line
+    character(len=:), allocatable, intent(inout) :: line !< line
+    character(len=*), intent(out) :: ctagfound !< block name
+    integer(I4B), intent(inout) :: iuext !< external file unit number
+    ! -- local variables
+    integer(I4B) :: ierr, istart, istop
+    integer(I4B) :: ival, lloc2
+    real(DP) :: rval
+    character(len=100) :: ermsg
+    character(len=:), allocatable :: line2
+    character(len=LINELENGTH) :: fname
+    !
+    ! -- code
+    isfound = .false.
+    ctagfound = ''
+    iuext = iin
+    do
+      lloc = 1
+      call line_reader%rdcom(iin, iout, line, ierr)
+      if (ierr < 0) exit
+      call urword(line, lloc, istart, istop, 1, ival, rval, iin, iout)
+      if (line(istart:istop) == 'BEGIN') then
+        call urword(line, lloc, istart, istop, 1, ival, rval, iin, iout)
+        if (line(istart:istop) /= '') then
+          isfound = .true.
+          ctagfound = line(istart:istop)
+          call line_reader%rdcom(iin, iout, line2, ierr)
+          if (ierr < 0) exit
+          lloc2 = 1
+          call urword(line2, lloc2, istart, istop, 1, ival, rval, iout, iin)
+          if (line2(istart:istop) == 'OPEN/CLOSE') then
+            iuext = io_getunit()
+            call urword(line2, lloc2, istart, istop, 0, ival, rval, iout, iin)
+            fname = line2(istart:istop)
+            call openfile(iuext, iout, fname, 'OPEN/CLOSE')
+          else
+            call line_reader%bkspc(iin)
+          end if
+        else
+          ermsg = 'Block name missing in file.'
+          call store_error(ermsg)
+          call store_error_unit(iin)
+        end if
+        exit
+      end if
+    end do
+    return
+  end subroutine uget_any_block
+
+  !> @brief Evaluate if the end of a block has been found
+  !!
+  !! Subroutine to evaluate if the end of a block has been found. Abnormal
+  !! termination if 'begin' is found or if 'end' encountered with
+  !! incorrect tag.
+  !!
+  !<
+  subroutine uterminate_block(iin, iout, key, ctag, lloc, line, ierr, iuext)
+    implicit none
+    ! -- dummy variables
+    integer(I4B), intent(in) :: iin !< file unit number
+    integer(I4B), intent(in) :: iout !< output listing file unit number
+    character(len=*), intent(in) :: key !< keyword in block
+    character(len=*), intent(in) :: ctag !< block name
+    integer(I4B), intent(inout) :: lloc !< position in line
+    character(len=*), intent(inout) :: line !< line
+    integer(I4B), intent(inout) :: ierr !< error
+    integer(I4B), intent(inout) :: iuext !< external file unit number
+    ! -- local variables
+    character(len=LENBIGLINE) :: ermsg
+    integer(I4B) :: istart
+    integer(I4B) :: istop
+    integer(I4B) :: ival
+    real(DP) :: rval
+    ! -- format
+1   format('ERROR. "', A, '" DETECTED WITHOUT "', A, '". ', '"END', 1X, A, &
+           '" MUST BE USED TO END ', A, '.')
+2   format('ERROR. "', A, '" DETECTED BEFORE "END', 1X, A, '". ', '"END', 1X, A, &
+           '" MUST BE USED TO END ', A, '.')
+    !
+    ! -- code
+    ierr = 1
+    select case (key)
+    case ('END')
+      call urword(line, lloc, istart, istop, 1, ival, rval, iout, iin)
+      if (line(istart:istop) /= ctag) then
+        write (ermsg, 1) trim(key), trim(ctag), trim(ctag), trim(ctag)
+        call store_error(ermsg)
+        call store_error_unit(iin)
+      else
+        ierr = 0
+        if (iuext /= iin) then
+          ! -- close external file
+          close (iuext)
+          iuext = iin
+        end if
+      end if
+    case ('BEGIN')
+      write (ermsg, 2) trim(key), trim(ctag), trim(ctag), trim(ctag)
+      call store_error(ermsg)
+      call store_error_unit(iin)
+    end select
+    !
+    ! -- return
+    return
+  end subroutine uterminate_block
+
 end module BlockParserModule
diff --git a/src/Utilities/BudgetObject.f90 b/src/Utilities/BudgetObject.f90
index 35836bf50b6..87819b7dd10 100644
--- a/src/Utilities/BudgetObject.f90
+++ b/src/Utilities/BudgetObject.f90
@@ -77,23 +77,17 @@ module BudgetObjectModule
 
 contains
 
+  !> @brief Create a new budget object
+  !<
   subroutine budgetobject_cr(this, name)
-! ******************************************************************************
-! budgetobject_cr -- Create a new budget object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     type(BudgetObjectType), pointer :: this
     character(len=*), intent(in) :: name
-! ------------------------------------------------------------------------------
     !
     ! -- Create the object
     allocate (this)
     !
-    ! -- initialize variables
+    ! -- Initialize variables
     this%name = name
     this%ncv = 0
     this%nbudterm = 0
@@ -101,23 +95,18 @@ subroutine budgetobject_cr(this, name)
     this%nsto = 0
     this%iterm = 0
     !
-    ! -- initialize budget table
+    ! -- Initialize budget table
     call budget_cr(this%budtable, name)
     !
     ! -- Return
     return
   end subroutine budgetobject_cr
 
+  !> @brief Define the new budget object
+  !<
   subroutine budgetobject_df(this, ncv, nbudterm, iflowja, nsto, &
                              bddim_opt, labeltitle_opt, bdzone_opt, &
                              ibudcsv)
-! ******************************************************************************
-! budgetobject_df -- Define the new budget object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BudgetObjectType) :: this
     integer(I4B), intent(in) :: ncv
@@ -133,7 +122,6 @@ subroutine budgetobject_df(this, ncv, nbudterm, iflowja, nsto, &
     character(len=5) :: bddim
     character(len=16) :: labeltitle
     character(len=20) :: bdzone
-! ------------------------------------------------------------------------------
     !
     ! -- set values
     this%ncv = ncv
@@ -141,7 +129,7 @@ subroutine budgetobject_df(this, ncv, nbudterm, iflowja, nsto, &
     this%iflowja = iflowja
     this%nsto = nsto
     !
-    ! -- allocate space for budterm
+    ! -- Allocate space for budterm
     allocate (this%budterm(nbudterm))
     !
     ! -- Set the budget type to name
@@ -168,7 +156,7 @@ subroutine budgetobject_df(this, ncv, nbudterm, iflowja, nsto, &
       labeltitle = 'PACKAGE NAME'
     end if
     !
-    ! -- setup the budget table object
+    ! -- Setup the budget table object
     call this%budtable%budget_df(nbudterm, bdtype, bddim, labeltitle, bdzone)
     !
     ! -- Trigger csv output
@@ -180,14 +168,9 @@ subroutine budgetobject_df(this, ncv, nbudterm, iflowja, nsto, &
     return
   end subroutine budgetobject_df
 
+  !> @brief Define the new flow table object
+  !<
   subroutine flowtable_df(this, iout, cellids)
-! ******************************************************************************
-! flowtable_df -- Define the new flow table object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BudgetObjectType) :: this
     integer(I4B), intent(in) :: iout
@@ -204,9 +187,8 @@ subroutine flowtable_df(this, iout, cellids)
     integer(I4B) :: idx
     integer(I4B) :: ipos
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
-    ! -- process optional variables
+    ! -- Process optional variables
     if (present(cellids)) then
       add_cellids = .TRUE.
       coupletype = cellids
@@ -214,17 +196,17 @@ subroutine flowtable_df(this, iout, cellids)
       add_cellids = .FALSE.
     end if
     !
-    ! -- allocate scalars
+    ! -- Allocate scalars
     allocate (this%add_cellids)
     allocate (this%icellid)
     allocate (this%nflowterms)
     !
-    ! -- initialize scalars
+    ! -- Initialize scalars
     this%add_cellids = add_cellids
     this%nflowterms = 0
     this%icellid = 0
     !
-    ! -- determine the number of columns in the table
+    ! -- Determine the number of columns in the table
     maxcol = 3
     if (add_cellids) then
       maxcol = maxcol + 1
@@ -249,11 +231,11 @@ subroutine flowtable_df(this, iout, cellids)
       end if
     end do
     !
-    ! -- allocate arrays
+    ! -- Allocate arrays
     allocate (this%istart(this%nflowterms))
     allocate (this%iflowterms(this%nflowterms))
     !
-    ! -- set up flow tableobj
+    ! -- Set up flow tableobj
     title = trim(this%name)//' PACKAGE - SUMMARY OF FLOWS FOR '// &
             'EACH CONTROL VOLUME'
     call table_cr(this%flowtab, this%name, title)
@@ -299,13 +281,9 @@ subroutine flowtable_df(this, iout, cellids)
     return
   end subroutine flowtable_df
 
+  !> @brief Add up accumulators and submit to budget table
+  !<
   subroutine accumulate_terms(this)
-! ******************************************************************************
-! accumulate_terms -- add up accumulators and submit to budget table
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: delt
     ! -- dummy
@@ -314,49 +292,42 @@ subroutine accumulate_terms(this)
     character(len=LENBUDTXT) :: flowtype
     integer(I4B) :: i
     real(DP) :: ratin, ratout
-! ------------------------------------------------------------------------------
     !
-    ! -- reset the budget table
+    ! -- Reset the budget table
     call this%budtable%reset()
     !
-    ! -- calculate the budget table terms
+    ! -- Calculate the budget table terms
     do i = 1, this%nbudterm
       !
-      ! -- accumulate positive and negative flows for each budget term
+      ! -- Accumulate positive and negative flows for each budget term
       flowtype = this%budterm(i)%flowtype
       select case (trim(adjustl(flowtype)))
       case ('FLOW-JA-FACE')
-        ! skip
+        ! -- Skip
       case default
         !
-        ! -- calculate sum of positive and negative flows
+        ! -- Calculate sum of positive and negative flows
         call this%budterm(i)%accumulate_flow(ratin, ratout)
         !
-        ! -- pass accumulators into the budget table
+        ! -- Pass accumulators into the budget table
         call this%budtable%addentry(ratin, ratout, delt, flowtype)
       end select
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine accumulate_terms
 
+  !> @brief Write the flow table for each advanced package control volume
+  !<
   subroutine write_flowtable(this, dis, kstp, kper, cellidstr)
-! ******************************************************************************
-! write_flowtable -- Write the flow table for each advanced package control
-!                    volume
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BudgetObjectType) :: this
     class(DisBaseType), intent(in) :: dis
     integer(I4B), intent(in) :: kstp
     integer(I4B), intent(in) :: kper
     character(len=20), dimension(:), optional :: cellidstr
-    ! -- dummy
+    ! -- local
     character(len=LENBUDTXT) :: flowtype
     character(len=20) :: cellid
     integer(I4B) :: nlist
@@ -375,25 +346,24 @@ subroutine write_flowtable(this, dis, kstp, kper, cellidstr)
     real(DP) :: qerr
     real(DP) :: qavg
     real(DP) :: qpd
-! ------------------------------------------------------------------------------
     !
-    ! -- reset starting position
+    ! -- Reset starting position
     do j = 1, this%nflowterms
       this%istart(j) = 1
     end do
     !
-    ! -- set table kstp and kper
+    ! -- Set table kstp and kper
     call this%flowtab%set_kstpkper(kstp, kper)
     !
-    ! -- write the table
+    ! -- Write the table
     do icv = 1, this%ncv
       call this%flowtab%add_term(icv)
       !
-      ! -- initialize flow terms for the control volume
+      ! -- Initialize flow terms for the control volume
       qin = DZERO
       qout = DZERO
       !
-      ! -- add cellid if required
+      ! -- Add cellid if required
       if (this%add_cellids) then
         if (present(cellidstr)) then
           !
@@ -419,21 +389,21 @@ subroutine write_flowtable(this, dis, kstp, kper, cellidstr)
         call this%flowtab%add_term(cellid)
       end if
       !
-      ! -- iterate over the flow terms
+      ! -- Iterate over the flow terms
       do j = 1, this%nflowterms
         !
-        ! -- initialize flow terms for the row
+        ! -- Initialize flow terms for the row
         q = DZERO
         qinflow = DZERO
         qoutflow = DZERO
         !
-        ! -- determine the index, flowtype and length of
+        ! -- Determine the index, flowtype and length of
         !    the flowterm
         idx = this%iflowterms(j)
         flowtype = this%budterm(idx)%get_flowtype()
         nlist = this%budterm(idx)%get_nlist()
         !
-        ! -- iterate over the entries in the flowtype.  If id1 is not ordered
+        ! -- Iterate over the entries in the flowtype.  If id1 is not ordered
         !    then need to look through the entire list each time
         colterm: do i = this%istart(j), nlist
           id1 = this%budterm(idx)%get_id1(i)
@@ -454,7 +424,7 @@ subroutine write_flowtable(this, dis, kstp, kper, cellidstr)
             end if
           end if
           !
-          ! -- accumulators
+          ! -- Accumulators
           q = q + v
           if (v < DZERO) then
             qout = qout + v
@@ -463,7 +433,7 @@ subroutine write_flowtable(this, dis, kstp, kper, cellidstr)
           end if
         end do colterm
         !
-        ! -- add entry to table
+        ! -- Add entry to table
         if (trim(adjustl(flowtype)) == 'FLOW-JA-FACE') then
           call this%flowtab%add_term(qinflow)
           call this%flowtab%add_term(qoutflow)
@@ -472,7 +442,7 @@ subroutine write_flowtable(this, dis, kstp, kper, cellidstr)
         end if
       end do
       !
-      ! -- calculate in-out and percent difference
+      ! -- Calculate in-out and percent difference
       qerr = qin + qout
       qavg = DHALF * (qin - qout)
       qpd = DZERO
@@ -483,18 +453,13 @@ subroutine write_flowtable(this, dis, kstp, kper, cellidstr)
       call this%flowtab%add_term(qpd)
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine write_flowtable
 
+  !> @brief Write the budget table
+  !<
   subroutine write_budtable(this, kstp, kper, iout, ibudfl, totim)
-! ******************************************************************************
-! write_budtable -- Write the budget table
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BudgetObjectType) :: this
     integer(I4B), intent(in) :: kstp
@@ -502,28 +467,21 @@ subroutine write_budtable(this, kstp, kper, iout, ibudfl, totim)
     integer(I4B), intent(in) :: iout
     integer(I4B), intent(in) :: ibudfl
     real(DP), intent(in) :: totim
-    ! -- dummy
-! ------------------------------------------------------------------------------
     !
-    ! -- write the table
+    ! -- Write the table
     if (ibudfl /= 0) then
       call this%budtable%budget_ot(kstp, kper, iout)
     end if
     call this%budtable%writecsv(totim)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine write_budtable
 
+  !> @brief Write the budget table
+  !<
   subroutine save_flows(this, dis, ibinun, kstp, kper, delt, &
                         pertim, totim, iout)
-! ******************************************************************************
-! write_budtable -- Write the budget table
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BudgetObjectType) :: this
     class(DisBaseType), intent(in) :: dis
@@ -536,26 +494,20 @@ subroutine save_flows(this, dis, ibinun, kstp, kper, delt, &
     integer(I4B), intent(in) :: iout
     ! -- dummy
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
-    ! -- save flows for each budget term
+    ! -- Save flows for each budget term
     do i = 1, this%nbudterm
       call this%budterm(i)%save_flows(dis, ibinun, kstp, kper, delt, &
                                       pertim, totim, iout)
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine save_flows
 
+  !> @brief Read froms from a binary file into this BudgetObjectType
+  !<
   subroutine read_flows(this, dis, ibinun)
-! ******************************************************************************
-! read_flows -- Read froms from a binary file into this BudgetObjectType
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BudgetObjectType) :: this
     class(DisBaseType), intent(in) :: dis
@@ -568,38 +520,31 @@ subroutine read_flows(this, dis, ibinun)
     real(DP) :: totim
     ! -- dummy
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
-    ! -- read flows for each budget term
+    ! -- Read flows for each budget term
     do i = 1, this%nbudterm
       call this%budterm(i)%read_flows(dis, ibinun, kstp, kper, delt, &
                                       pertim, totim)
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine read_flows
 
+  !> @brief Deallocate
+  !<
   subroutine budgetobject_da(this)
-! ******************************************************************************
-! budgetobject_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BudgetObjectType) :: this
     ! -- dummy
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
-    ! -- save flows for each budget term
+    ! -- Save flows for each budget term
     do i = 1, this%nbudterm
       call this%budterm(i)%deallocate_arrays()
     end do
     !
-    ! -- destroy the flow table
+    ! -- Destroy the flow table
     if (associated(this%flowtab)) then
       deallocate (this%add_cellids)
       deallocate (this%icellid)
@@ -611,7 +556,7 @@ subroutine budgetobject_da(this)
       nullify (this%flowtab)
     end if
     !
-    ! -- destroy the budget object table
+    ! -- Destroy the budget object table
     if (associated(this%budtable)) then
       call this%budtable%budget_da()
       deallocate (this%budtable)
@@ -622,14 +567,9 @@ subroutine budgetobject_da(this)
     return
   end subroutine budgetobject_da
 
+  !> @brief Create a new budget object from a binary flow file
+  !<
   subroutine budgetobject_cr_bfr(this, name, ibinun, iout, colconv1, colconv2)
-! ******************************************************************************
-! budgetobject_cr_bfr -- Create a new budget object from a binary flow file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     type(BudgetObjectType), pointer :: this
     character(len=*), intent(in) :: name
@@ -641,7 +581,6 @@ subroutine budgetobject_cr_bfr(this, name, ibinun, iout, colconv1, colconv2)
     integer(I4B) :: ncv, nbudterm
     integer(I4B) :: iflowja, nsto
     integer(I4B) :: i, j
-! ------------------------------------------------------------------------------
     !
     ! -- Create the object
     call budgetobject_cr(this, name)
@@ -682,24 +621,17 @@ subroutine budgetobject_cr_bfr(this, name, ibinun, iout, colconv1, colconv2)
     return
   end subroutine budgetobject_cr_bfr
 
+  !> @brief Initialize the budget file reader
+  !<
   subroutine bfr_init(this, ibinun, ncv, nbudterm, iout)
-! ******************************************************************************
-! bfr_init -- initialize the budget file reader
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BudgetObjectType) :: this
     integer(I4B), intent(in) :: ibinun
     integer(I4B), intent(inout) :: ncv
     integer(I4B), intent(inout) :: nbudterm
     integer(I4B), intent(in) :: iout
-    ! -- local
-! ------------------------------------------------------------------------------
     !
-    ! -- initialize budget file reader
+    ! -- Initialize budget file reader
     allocate (this%bfr)
     call this%bfr%initialize(ibinun, iout, ncv)
     nbudterm = this%bfr%nbudterms
@@ -708,13 +640,10 @@ subroutine bfr_init(this, ibinun, ncv, nbudterm, iout)
     return
   end subroutine bfr_init
 
+  !> @brief Advance the binary file readers for setting the budget terms of
+  !! the next time step
+  !<
   subroutine bfr_advance(this, dis, iout)
-! ******************************************************************************
-! bfr_advance -- copy the information from the binary file into budterms
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use TdisModule, only: kstp, kper
     ! -- dummy
@@ -728,7 +657,6 @@ subroutine bfr_advance(this, dis, iout)
     character(len=*), parameter :: fmtbudkstpkper = &
       "(1x,/1x, a, ' SETTING BUDGET TERMS FOR KSTP ', i0, ' AND KPER ', &
       &i0, ' TO BUDGET FILE TERMS FROM KSTP ', i0, ' AND KPER ', i0)"
-! ------------------------------------------------------------------------------
     !
     ! -- Do not read the budget if the budget is at end of file or if the next
     !    record in the budget file is the first timestep of the next stress
@@ -753,7 +681,7 @@ subroutine bfr_advance(this, dis, iout)
       if (iout > 0) &
         write (iout, fmtkstpkper) this%name, kstp, kper
       !
-      ! -- read flows from the binary file and copy them into this%budterm(:)
+      ! -- Read flows from the binary file and copy them into this%budterm(:)
       call this%fill_from_bfr(dis, iout)
     else
       if (iout > 0) &
@@ -765,14 +693,9 @@ subroutine bfr_advance(this, dis, iout)
     return
   end subroutine bfr_advance
 
+  !> @brief Copy the information from the binary file into budterms
+  !<
   subroutine fill_from_bfr(this, dis, iout)
-! ******************************************************************************
-! fill_from_bfr -- copy the information from the binary file into budterms
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BudgetObjectType) :: this
     class(DisBaseType), intent(in) :: dis
@@ -780,9 +703,8 @@ subroutine fill_from_bfr(this, dis, iout)
     ! -- dummy
     integer(I4B) :: i
     logical :: success
-! ------------------------------------------------------------------------------
     !
-    ! -- read flows from the binary file and copy them into this%budterm(:)
+    ! -- Read flows from the binary file and copy them into this%budterm(:)
     do i = 1, this%nbudterm
       call this%bfr%read_record(success, iout)
       call this%budterm(i)%fill_from_bfr(this%bfr, dis)
diff --git a/src/Utilities/BudgetTerm.f90 b/src/Utilities/BudgetTerm.f90
index e3aeb13a67a..24de025e39d 100644
--- a/src/Utilities/BudgetTerm.f90
+++ b/src/Utilities/BudgetTerm.f90
@@ -54,16 +54,11 @@ module BudgetTermModule
 
 contains
 
+  !> @brief Initialize the budget term
+  !<
   subroutine initialize(this, flowtype, text1id1, text2id1, &
                         text1id2, text2id2, maxlist, olconv1, olconv2, &
                         naux, auxtxt, ordered_id1)
-! ******************************************************************************
-! initialize -- initialize the budget term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BudgetTermType) :: this
     character(len=LENBUDTXT), intent(in) :: flowtype
@@ -77,8 +72,7 @@ subroutine initialize(this, flowtype, text1id1, text2id1, &
     integer(I4B), intent(in) :: naux
     character(len=LENBUDTXT), dimension(:), intent(in), optional :: auxtxt
     logical, intent(in), optional :: ordered_id1
-    ! -- local
-! ------------------------------------------------------------------------------
+    !
     this%flowtype = flowtype
     this%text1id1 = text1id1
     this%text2id1 = text2id1
@@ -93,37 +87,29 @@ subroutine initialize(this, flowtype, text1id1, text2id1, &
     if (present(auxtxt)) this%auxtxt(:) = auxtxt(1:naux)
     this%ordered_id1 = .true.
     if (present(ordered_id1)) this%ordered_id1 = ordered_id1
+    !
   end subroutine initialize
 
+  !> @brief Allocate budget term arrays
+  !<
   subroutine allocate_arrays(this)
-! ******************************************************************************
-! allocate_arrays -- allocate budget term arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BudgetTermType) :: this
-! ------------------------------------------------------------------------------
+    !
     allocate (this%id1(this%maxlist))
     allocate (this%id2(this%maxlist))
     allocate (this%flow(this%maxlist))
     allocate (this%auxvar(this%naux, this%maxlist))
     allocate (this%auxtxt(this%naux))
+    !
   end subroutine allocate_arrays
 
+  !> @brief Deallocate budget term arrays
+  !<
   subroutine deallocate_arrays(this)
-! ******************************************************************************
-! deallocate_arrays -- deallocate budget term arrays
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BudgetTermType) :: this
-! ------------------------------------------------------------------------------
+    !
     deallocate (this%id1)
     deallocate (this%id2)
     deallocate (this%flow)
@@ -131,53 +117,40 @@ subroutine deallocate_arrays(this)
     deallocate (this%auxtxt)
   end subroutine deallocate_arrays
 
+  !> @brief reset the budget term and counter so terms can be updated
+  !<
   subroutine reset(this, nlist)
-! ******************************************************************************
-! reset -- reset the budget term and counter so terms can be updated
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BudgetTermType) :: this
     integer(I4B), intent(in) :: nlist
-! ------------------------------------------------------------------------------
+    !
     this%nlist = nlist
     this%icounter = 1
+    !
   end subroutine reset
 
+  !> @brief replace the terms in position this%icounter for id1, id2, flow,
+  !! and aux
+  !<
   subroutine update_term(this, id1, id2, flow, auxvar)
-! ******************************************************************************
-! update_term -- replace the terms in position this%icounter
-!   for id1, id2, flow, and aux
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BudgetTermType) :: this
     integer(I4B), intent(in) :: id1
     integer(I4B), intent(in) :: id2
     real(DP), intent(in) :: flow
     real(DP), dimension(:), intent(in), optional :: auxvar
-! ------------------------------------------------------------------------------
+    !
     this%id1(this%icounter) = id1
     this%id2(this%icounter) = id2
     this%flow(this%icounter) = flow
     if (present(auxvar)) this%auxvar(:, this%icounter) = auxvar(1:this%naux)
     this%icounter = this%icounter + 1
+    !
   end subroutine update_term
 
+  !> @brief Calculate ratin and ratout for all the flow terms
+  !<
   subroutine accumulate_flow(this, ratin, ratout)
-! ******************************************************************************
-! accumulate_flow -- calculate ratin and ratout for all the flow terms
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BudgetTermType) :: this
     real(DP), intent(inout) :: ratin
@@ -185,7 +158,7 @@ subroutine accumulate_flow(this, ratin, ratout)
     ! -- local
     integer(I4B) :: i
     real(DP) :: q
-! ------------------------------------------------------------------------------
+    !
     ratin = DZERO
     ratout = DZERO
     do i = 1, this%nlist
@@ -196,17 +169,13 @@ subroutine accumulate_flow(this, ratin, ratout)
         ratin = ratin + q
       end if
     end do
+    !
   end subroutine accumulate_flow
 
+  !> @brief Write flows to a binary file
+  !<
   subroutine save_flows(this, dis, ibinun, kstp, kper, delt, pertim, totim, &
                         iout)
-! ******************************************************************************
-! save_flows -- write flows to a binary file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BudgetTermType) :: this
     class(DisBaseType), intent(in) :: dis
@@ -223,7 +192,6 @@ subroutine save_flows(this, dis, ibinun, kstp, kper, delt, pertim, totim, &
     integer(I4B) :: n1
     integer(I4B) :: n2
     real(DP) :: q
-! ------------------------------------------------------------------------------
     !
     ! -- Count the size of the list and exclude ids less than or equal to zero
     nlist = 0
@@ -253,114 +221,75 @@ subroutine save_flows(this, dis, ibinun, kstp, kper, delt, pertim, totim, &
                                      olconv=this%olconv1, &
                                      olconv2=this%olconv2)
     end do
+    !
   end subroutine save_flows
 
+  !> @brief Get the number of entries for the stress period
+  !<
   function get_nlist(this) result(nlist)
-! ******************************************************************************
-! get_nlist -- get the number of entries for the stress period
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    ! -- return
-    integer(I4B) :: nlist
     ! -- dummy
     class(BudgetTermType) :: this
-! ------------------------------------------------------------------------------
+    ! -- return
+    integer(I4B) :: nlist
+    !
     nlist = this%nlist
     !
-    ! -- return
-    return
   end function get_nlist
 
+  !> @brief Get the flowtype for the budget term
+  !<
   function get_flowtype(this) result(flowtype)
-! ******************************************************************************
-! get_flowtype -- get the flowtype for the budget term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    ! -- return
-    character(len=LENBUDTXT) :: flowtype
     ! -- dummy
     class(BudgetTermType) :: this
-! ------------------------------------------------------------------------------
+    ! -- return
+    character(len=LENBUDTXT) :: flowtype
+    !
     flowtype = this%flowtype
     !
-    ! -- return
-    return
   end function get_flowtype
 
+  !> @brief Get id1(icount) for the budget term
+  !<
   function get_id1(this, icount) result(id1)
-! ******************************************************************************
-! get_id1 -- get id1(icount) for the budget term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
-    ! -- return
-    integer(I4B) :: id1
     ! -- dummy
     class(BudgetTermType) :: this
     integer(I4B), intent(in) :: icount
-! ------------------------------------------------------------------------------
+    ! -- return
+    integer(I4B) :: id1
+    !
     id1 = this%id1(icount)
     !
-    ! -- return
-    return
   end function get_id1
 
+  !> @brief Get id2(icount) for the budget term
+  !<
   function get_id2(this, icount) result(id2)
-! ******************************************************************************
-! get_id2 -- get id2(icount) for the budget term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- return
     integer(I4B) :: id2
     ! -- dummy
     class(BudgetTermType) :: this
     integer(I4B), intent(in) :: icount
-! ------------------------------------------------------------------------------
+    !
     id2 = this%id2(icount)
     !
-    ! -- return
-    return
   end function get_id2
 
+  !> @brief Get flow(icount) for the budget term
+  !<
   function get_flow(this, icount) result(flow)
-! ******************************************************************************
-! get_flow -- get flow(icount) for the budget term
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- return
     real(DP) :: flow
     ! -- dummy
     class(BudgetTermType) :: this
     integer(I4B), intent(in) :: icount
-! ------------------------------------------------------------------------------
+    !
     flow = this%flow(icount)
     !
-    ! -- return
-    return
   end function get_flow
 
+  !> @brief Read flows from a binary file
+  !<
   subroutine read_flows(this, dis, ibinun, kstp, kper, delt, pertim, totim)
-! ******************************************************************************
-! read_flows -- read flows from a binary file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(BudgetTermType) :: this
     class(DisBaseType), intent(in) :: dis
@@ -376,7 +305,7 @@ subroutine read_flows(this, dis, ibinun, kstp, kper, delt, pertim, totim)
     integer(I4B) :: n1
     integer(I4B) :: n2
     real(DP) :: q
-! ------------------------------------------------------------------------------
+    !
     read (ibinun) kstp, kper, this%flowtype, this%nlist, idum1, idum2
     read (ibinun) imeth, delt, pertim, totim
     read (ibinun) this%text1id1
@@ -393,6 +322,7 @@ subroutine read_flows(this, dis, ibinun, kstp, kper, delt, pertim, totim)
         allocate (this%auxtxt(this%naux))
       end if
     end if
+    !
     if (this%naux > 0) read (ibinun) (this%auxtxt(j), j=1, this%naux)
     read (ibinun) this%nlist
     if (.not. associated(this%id1)) then
@@ -414,6 +344,7 @@ subroutine read_flows(this, dis, ibinun, kstp, kper, delt, pertim, totim)
         allocate (this%auxvar(this%naux, this%maxlist))
       end if
     end if
+    !
     do i = 1, this%nlist
       read (ibinun) n1
       read (ibinun) n2
@@ -425,15 +356,12 @@ subroutine read_flows(this, dis, ibinun, kstp, kper, delt, pertim, totim)
       this%id2(i) = n2
       this%flow(i) = q
     end do
+    !
   end subroutine read_flows
 
+  !> @brief Copy the flow from the binary file reader into this budterm
+  !<
   subroutine fill_from_bfr(this, bfr, dis)
-! ******************************************************************************
-! fill_from_bfr -- copy the flow from the binary file reader into this budterm
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use BudgetFileReaderModule, only: BudgetFileReaderType
     ! -- dummy
@@ -445,13 +373,14 @@ subroutine fill_from_bfr(this, bfr, dis)
     integer(I4B) :: n1
     integer(I4B) :: n2
     real(DP) :: q
-! ------------------------------------------------------------------------------
+    !
     this%flowtype = bfr%budtxt
     this%text1id1 = bfr%srcmodelname
     this%text2id1 = bfr%srcpackagename
     this%text1id2 = bfr%dstmodelname
     this%text2id2 = bfr%dstpackagename
     this%naux = bfr%naux
+    !
     if (.not. associated(this%auxtxt)) then
       allocate (this%auxtxt(this%naux))
     else
@@ -460,6 +389,7 @@ subroutine fill_from_bfr(this, bfr, dis)
         allocate (this%auxtxt(this%naux))
       end if
     end if
+    !
     if (this%naux > 0) this%auxtxt(:) = bfr%auxtxt(:)
     this%nlist = bfr%nlist
     if (.not. associated(this%id1)) then
@@ -481,6 +411,7 @@ subroutine fill_from_bfr(this, bfr, dis)
         allocate (this%auxvar(this%naux, this%maxlist))
       end if
     end if
+    !
     do i = 1, this%nlist
       n1 = bfr%nodesrc(i)
       n2 = bfr%nodedst(i)
@@ -492,6 +423,7 @@ subroutine fill_from_bfr(this, bfr, dis)
       this%id2(i) = n2
       this%flow(i) = q
     end do
+    !
   end subroutine fill_from_bfr
 
 end module BudgetTermModule
diff --git a/src/Utilities/Constants.f90 b/src/Utilities/Constants.f90
index 784476c424f..718a9ae392c 100644
--- a/src/Utilities/Constants.f90
+++ b/src/Utilities/Constants.f90
@@ -81,6 +81,7 @@ module ConstantsModule
   real(DP), parameter :: DSIX = 6.0_DP !< real constant 6
   real(DP), parameter :: DEIGHT = 8.0_DP !< real constant 8
   real(DP), parameter :: DTEN = 1.0e1_DP !< real constant 10
+  real(DP), parameter :: DSIXTY = 6.0e1_DP !< real constant 60
   real(DP), parameter :: DHUNDRED = 1.0e2_DP !< real constant 100
 
   real(DP), parameter :: DEP3 = 1.0e3_DP !< real constant 1000
@@ -92,6 +93,12 @@ module ConstantsModule
   real(DP), parameter :: DHDRY = -1.e30_DP !< real dry cell constant
   real(DP), parameter :: DNODATA = 3.0e30_DP !< real no data constant
 
+  real(DP), parameter :: DSECPERHR = 3.6e3_DP !< real constant representing number of seconds per hour (used in tdis)
+  real(DP), parameter :: DHRPERDAY = 2.4e1_DP !< real constant representing number of hours per day (used in tdis)
+  real(DP), parameter :: DDYPERYR = 3.6525e2_DP !< real constant representing the average number of days per year (used in tdis)
+  real(DP), parameter :: DSECPERDY = 8.64e4_DP !< real constant representing the number of seconds per day (used in tdis)
+  real(DP), parameter :: DSECPERYR = 3.1557600e7_DP !< real constant representing the average number of seconds per year (used in tdis)
+
   real(DP), parameter :: DEM1 = 1.0e-1_DP !< real constant 1e-1
   real(DP), parameter :: D5EM2 = 5.0e-2_DP !< real constant 5e-2
   real(DP), parameter :: DEM2 = 1.0e-2_DP !< real constant 1e-2
diff --git a/src/Utilities/DevFeature.f90 b/src/Utilities/DevFeature.f90
new file mode 100644
index 00000000000..a36e1fb22e2
--- /dev/null
+++ b/src/Utilities/DevFeature.f90
@@ -0,0 +1,37 @@
+!> @brief Disable development features in release mode
+module DevFeatureModule
+  use KindModule, only: I4B
+  use VersionModule, only: IDEVELOPMODE
+  use SimModule, only: store_error, store_error_unit
+  implicit none
+  private
+  public :: dev_feature
+
+contains
+
+  !> @brief Terminate if in release mode (guard development features)
+  !!
+  !! Terminate the program with an error if the IDEVELOPMODE flag
+  !! is set to 0. This allows developing features on the mainline
+  !! while disabling them in release builds. An optional file unit
+  !! may be specified to associate the feature with an input file.
+  !!
+  !<
+  subroutine dev_feature(errmsg, iunit)
+    ! -- dummy
+    character(len=*), intent(in) :: errmsg
+    integer(I4B), intent(in), optional :: iunit
+
+    ! -- store error and terminate if in release mode
+    if (IDEVELOPMODE == 0) then
+      if (present(iunit)) then
+        call store_error(errmsg, terminate=.false.)
+        call store_error_unit(iunit, terminate=.true.)
+      else
+        call store_error(errmsg, terminate=.true.)
+      end if
+    end if
+
+  end subroutine dev_feature
+
+end module DevFeatureModule
diff --git a/src/Utilities/ErrorUtil.f90 b/src/Utilities/ErrorUtil.f90
new file mode 100644
index 00000000000..f967168d906
--- /dev/null
+++ b/src/Utilities/ErrorUtil.f90
@@ -0,0 +1,26 @@
+module ErrorUtilModule
+  use KindModule, only: I4B
+  implicit none
+contains
+
+  !> @brief Stop the program, optionally specifying an error status code.
+  !!
+  !! If a non-zero status is specified, the program is terminated with the
+  !! error status code. If no status is specified or status=0, the program
+  !! stops with code 0. A message may be provided to print before exiting,
+  !! useful e.g. for "contact developer" messages upon programming errors.
+  !<
+  subroutine pstop(status, message)
+    integer(I4B), intent(in), optional :: status !< optional error code to return (default=0)
+    character(len=*), intent(in), optional :: message !< optional message to print before stopping
+
+    if (present(message)) print *, message
+    if (present(status)) then
+      if (status == 0) stop
+      call exit(status)
+    else
+      stop
+    end if
+  end subroutine pstop
+
+end module ErrorUtilModule
diff --git a/src/Utilities/GeomUtil.f90 b/src/Utilities/GeomUtil.f90
new file mode 100644
index 00000000000..9d1bad53c2b
--- /dev/null
+++ b/src/Utilities/GeomUtil.f90
@@ -0,0 +1,360 @@
+module GeomUtilModule
+  use KindModule, only: I4B, DP, LGP
+  use ErrorUtilModule, only: pstop
+  use ConstantsModule, only: DZERO, DONE
+  implicit none
+  private
+  public :: between, point_in_polygon, &
+            get_node, get_ijk, get_jk, &
+            skew, transform, &
+            compose
+contains
+
+  !> @brief Check if a value is between two other values (inclusive).
+  logical function between(x, a, b)
+    real(DP), intent(in) :: x, a, b
+    between = ((x >= a .and. x <= b) .or. (x <= a .and. x >= b))
+  end function between
+
+  !> @brief Check if a point is within a polygon.
+  !! Vertices and edge points are considered in.
+  !! Reference: https://stackoverflow.com/a/63436180/6514033
+  logical function point_in_polygon(x, y, poly)
+    ! dummy
+    real(DP), intent(in) :: x !< x point coordinate
+    real(DP), intent(in) :: y !< y point coordinate
+    real(DP), allocatable, intent(in) :: poly(:, :) !< polygon vertices (column-major indexing)
+    ! local
+    integer(I4B) :: i, ii, num_verts
+    real(DP) :: xa, xb, ya, yb, c = 0.0_DP
+
+    point_in_polygon = .false.
+    num_verts = size(poly, 2)
+    xa = poly(1, num_verts)
+    ya = poly(2, num_verts)
+
+    do i = 0, num_verts - 1
+      ii = mod(i, num_verts) + 1
+      xb = poly(1, ii)
+      yb = poly(2, ii)
+
+      if ((x == xa .and. y == ya) .or. (x == xb .and. y == yb)) then
+        ! on vertex
+        point_in_polygon = .true.
+        exit
+      else if (ya == yb .and. y == ya .and. between(x, xa, xb)) then
+        ! on horizontal edge
+        point_in_polygon = .true.
+        exit
+      else if (between(y, ya, yb)) then
+        if ((y == ya .and. yb >= ya) .or. (y == yb .and. ya >= yb)) then
+          xa = xb
+          ya = yb
+          cycle
+        end if
+        ! cross product
+        c = (xa - x) * (yb - y) - (xb - x) * (ya - y)
+        if (c == 0) then
+          ! on edge
+          point_in_polygon = .true.
+          exit
+        else if ((ya < yb) .eqv. (c > 0)) then
+          ! ray intersection
+          point_in_polygon = .not. point_in_polygon
+        end if
+      end if
+
+      xa = xb
+      ya = yb
+    end do
+  end function point_in_polygon
+
+  !> @brief Get node number, given layer, row, and column indices
+  !! for a structured grid. If any argument is invalid return -1.
+  function get_node(ilay, irow, icol, nlay, nrow, ncol)
+    integer(I4B), intent(in) :: ilay, irow, icol, nlay, nrow, ncol
+    integer(I4B) :: get_node
+
+    if (nlay > 0 .and. nrow > 0 .and. ncol > 0 .and. &
+        ilay > 0 .and. ilay <= nlay .and. &
+        irow > 0 .and. irow <= nrow .and. &
+        icol > 0 .and. icol <= ncol) then
+      get_node = &
+        icol + ncol * (irow - 1) + (ilay - 1) * nrow * ncol
+    else
+      get_node = -1
+    end if
+  end function get_node
+
+  !> @brief Get row, column and layer indices from node number and grid
+  !! dimensions. If nodenumber is invalid, irow, icol, and ilay are -1.
+  subroutine get_ijk(nodenumber, nrow, ncol, nlay, irow, icol, ilay)
+    ! -- dummy variables
+    integer(I4B), intent(in) :: nodenumber
+    integer(I4B), intent(in) :: nrow
+    integer(I4B), intent(in) :: ncol
+    integer(I4B), intent(in) :: nlay
+    integer(I4B), intent(out) :: irow
+    integer(I4B), intent(out) :: icol
+    integer(I4B), intent(out) :: ilay
+    ! -- local variables
+    integer(I4B) :: nodes
+    integer(I4B) :: ij
+
+    nodes = nlay * nrow * ncol
+    if (nodenumber < 1 .or. nodenumber > nodes) then
+      irow = -1
+      icol = -1
+      ilay = -1
+    else
+      ilay = (nodenumber - 1) / (ncol * nrow) + 1
+      ij = nodenumber - (ilay - 1) * ncol * nrow
+      irow = (ij - 1) / ncol + 1
+      icol = ij - (irow - 1) * ncol
+    end if
+  end subroutine get_ijk
+
+  !> @brief Get layer index and within-layer node index from node number
+  !! and grid dimensions. If nodenumber is invalid, icpl and ilay are -1.
+  subroutine get_jk(nodenumber, ncpl, nlay, icpl, ilay)
+    ! -- dummy variables
+    integer(I4B), intent(in) :: nodenumber
+    integer(I4B), intent(in) :: ncpl
+    integer(I4B), intent(in) :: nlay
+    integer(I4B), intent(out) :: icpl
+    integer(I4B), intent(out) :: ilay
+    ! -- local variables
+    integer(I4B) :: nodes
+
+    nodes = ncpl * nlay
+    if (nodenumber < 1 .or. nodenumber > nodes) then
+      icpl = -1
+      ilay = -1
+    else
+      ilay = (nodenumber - 1) / ncpl + 1
+      icpl = nodenumber - (ilay - 1) * ncpl
+    end if
+  end subroutine get_jk
+
+  !> @brief Skew a 2D vector along the x-axis.
+  pure function skew(v, s, invert) result(res)
+    ! -- dummy
+    real(DP), intent(in) :: v(2) !< vector
+    real(DP), intent(in) :: s(3) !< skew matrix entries (top left, top right, bottom right)
+    logical(LGP), intent(in), optional :: invert
+    real(DP) :: res(2)
+    ! -- local
+    logical(LGP) :: linvert
+    real(DP) :: sxx, sxy, syy
+
+    ! -- process optional arguments
+    if (present(invert)) then
+      linvert = invert
+    else
+      linvert = .false.
+    end if
+
+    sxx = s(1)
+    sxy = s(2)
+    syy = s(3)
+    if (.not. linvert) then
+      res(1) = sxx * v(1) + sxy * v(2)
+      res(2) = syy * v(2)
+    else
+      res(2) = v(2) / syy
+      res(1) = (v(1) - sxy * res(2)) / sxx
+    end if
+  end function skew
+
+  !> @brief Apply a 3D translation and optional 2D rotation to coordinates.
+  subroutine transform(xin, yin, zin, &
+                       xout, yout, zout, &
+                       xorigin, yorigin, zorigin, &
+                       sinrot, cosrot, &
+                       invert)
+    ! -- dummy
+    real(DP) :: xin, yin, zin !< input coordinates
+    real(DP) :: xout, yout, zout !< output coordinates
+    real(DP), optional :: xorigin, yorigin, zorigin !< origin coordinates
+    real(DP), optional :: sinrot, cosrot !< sine and cosine of rotation
+    logical(LGP), optional :: invert !< whether to invert
+    ! -- local
+    logical(LGP) :: ltranslate, lrotate, linvert
+    real(DP) :: x, y
+    real(DP) :: lxorigin, lyorigin, lzorigin
+    real(DP) :: lsinrot, lcosrot
+
+    ! -- Process option arguments and set defaults and flags
+    call defaults(lxorigin, lyorigin, lzorigin, &
+                  lsinrot, lcosrot, linvert, &
+                  ltranslate, lrotate, &
+                  xorigin, yorigin, zorigin, &
+                  sinrot, cosrot, invert)
+
+    ! -- Apply transformation or its inverse
+    if (.not. linvert) then
+      ! -- Apply transformation to coordinates
+      if (ltranslate) then
+        xout = xin - lxorigin
+        yout = yin - lyorigin
+        zout = zin - lzorigin
+      else
+        xout = lxorigin
+        yout = lyorigin
+        zout = lzorigin
+      end if
+      if (lrotate) then
+        x = xout
+        y = yout
+        xout = x * lcosrot + y * lsinrot
+        yout = -x * lsinrot + y * lcosrot
+      end if
+    else
+      ! -- Apply inverse of transformation to coordinates
+      if (lrotate) then
+        x = xin * lcosrot - yin * lsinrot
+        y = xin * lsinrot + yin * lcosrot
+      else
+        x = xin
+        y = yin
+      end if
+      if (ltranslate) then
+        xout = x + lxorigin
+        yout = y + lyorigin
+        zout = zin + lzorigin
+      end if
+    end if
+  end subroutine transform
+
+  !> @brief Apply a 3D translation and 2D rotation to an existing transformation.
+  subroutine compose(xorigin, yorigin, zorigin, &
+                     sinrot, cosrot, &
+                     xorigin_new, yorigin_new, zorigin_new, &
+                     sinrot_new, cosrot_new, &
+                     invert)
+    ! -- dummy
+    real(DP) :: xorigin, yorigin, zorigin !< origin coordinates (original)
+    real(DP) :: sinrot, cosrot !< sine and cosine of rotation (original)
+    real(DP), optional :: xorigin_new, yorigin_new, zorigin_new !< origin coordinates (new)
+    real(DP), optional :: sinrot_new, cosrot_new !< sine and cosine of rotation (new)
+    logical(LGP), optional :: invert !< whether to invert
+    ! -- local
+    logical(LGP) :: ltranslate, lrotate, linvert
+    real(DP) :: xorigin_add, yorigin_add, zorigin_add
+    real(DP) :: sinrot_add, cosrot_add
+    real(DP) :: x0, y0, z0, s0, c0
+
+    ! -- Process option arguments and set defaults and flags
+    call defaults(xorigin_add, yorigin_add, zorigin_add, &
+                  sinrot_add, cosrot_add, linvert, &
+                  ltranslate, lrotate, &
+                  xorigin_new, yorigin_new, zorigin_new, &
+                  sinrot_new, cosrot_new, invert)
+
+    ! -- Copy existing transformation into working copy
+    x0 = xorigin
+    y0 = yorigin
+    z0 = zorigin
+    s0 = sinrot
+    c0 = cosrot
+
+    ! -- Modify transformation
+    if (.not. linvert) then
+      ! -- Apply additional transformation to existing transformation
+      if (ltranslate) then
+        ! -- Calculate modified origin, XOrigin + R^T XOrigin_add, where
+        ! -- XOrigin and XOrigin_add are the existing and additional origin
+        ! -- vectors, respectively, and R^T is the transpose of the existing
+        ! -- rotation matrix
+        call transform(xorigin_add, yorigin_add, zorigin_add, &
+                       xorigin, yorigin, zorigin, &
+                       x0, y0, z0, s0, c0, .true.)
+      end if
+      if (lrotate) then
+        ! -- Calculate modified rotation matrix (represented by sinrot
+        ! -- and cosrot) as R_add R, where R and R_add are the existing
+        ! -- and additional rotation matrices, respectively
+        sinrot = cosrot_add * s0 + sinrot_add * c0
+        cosrot = cosrot_add * c0 - sinrot_add * s0
+      end if
+    else
+      ! -- Apply inverse of additional transformation to existing transformation
+      !
+      ! -- Calculate modified origin, R^T (XOrigin + R_add XOrigin_add), where
+      ! -- XOrigin and XOrigin_add are the existing and additional origin
+      ! -- vectors, respectively, R^T is the transpose of the existing rotation
+      ! -- matrix, and R_add is the additional rotation matrix
+      if (ltranslate) then
+        call transform(-xorigin_add, -yorigin_add, zorigin_add, &
+                       x0, y0, z0, xorigin, yorigin, zorigin, &
+                       -sinrot_add, cosrot_add, .true.)
+      end if
+      xorigin = c0 * x0 - s0 * y0
+      yorigin = s0 * x0 + c0 * y0
+      zorigin = z0
+      if (lrotate) then
+        ! -- Calculate modified rotation matrix (represented by sinrot
+        ! -- and cosrot) as R_add^T R, where R and R_add^T are the existing
+        ! -- rotation matirx and the transpose of the additional rotation
+        ! -- matrix, respectively
+        sinrot = cosrot_add * s0 - sinrot_add * c0
+        cosrot = cosrot_add * c0 + sinrot_add * s0
+      end if
+    end if
+  end subroutine compose
+
+  !> @brief Process arguments and set defaults. Internal use only.
+  subroutine defaults(xorigin, yorigin, zorigin, &
+                      sinrot, cosrot, &
+                      invert, translate, rotate, &
+                      xorigin_opt, yorigin_opt, zorigin_opt, &
+                      sinrot_opt, cosrot_opt, invert_opt)
+    ! -- dummy
+    real(DP) :: xorigin, yorigin, zorigin
+    real(DP) :: sinrot, cosrot
+    logical(LGP) :: invert, translate, rotate
+    real(DP), optional :: xorigin_opt, yorigin_opt, zorigin_opt
+    real(DP), optional :: sinrot_opt, cosrot_opt
+    logical(LGP), optional :: invert_opt
+
+    translate = .false.
+    xorigin = DZERO
+    if (present(xorigin_opt)) then
+      xorigin = xorigin_opt
+      translate = .true.
+    end if
+    yorigin = DZERO
+    if (present(yorigin_opt)) then
+      yorigin = yorigin_opt
+      translate = .true.
+    end if
+    zorigin = DZERO
+    if (present(zorigin_opt)) then
+      zorigin = zorigin_opt
+      translate = .true.
+    end if
+    rotate = .false.
+    sinrot = DZERO
+    cosrot = DONE
+    if (present(sinrot_opt)) then
+      sinrot = sinrot_opt
+      if (present(cosrot_opt)) then
+        cosrot = cosrot_opt
+      else
+        ! -- If sinrot_opt is specified but cosrot_opt is not,
+        ! -- default to corresponding non-negative cosrot_add
+        cosrot = dsqrt(DONE - sinrot * sinrot)
+      end if
+      rotate = .true.
+    else if (present(cosrot_opt)) then
+      cosrot = cosrot_opt
+      ! -- cosrot_opt is specified but sinrot_opt is not, so
+      ! -- default to corresponding non-negative sinrot_add
+      sinrot = dsqrt(DONE - cosrot * cosrot)
+      rotate = .true.
+    end if
+    invert = .false.
+    if (present(invert_opt)) invert = invert_opt
+  end subroutine defaults
+
+end module GeomUtilModule
diff --git a/src/Utilities/HashTable.f90 b/src/Utilities/HashTable.f90
index 51f90b04efd..536d50ebe47 100644
--- a/src/Utilities/HashTable.f90
+++ b/src/Utilities/HashTable.f90
@@ -1,13 +1,9 @@
-! HashTableType implements a hash table for storing integers,
-! for use as an index for an array that could contain
-! any data type.  This HashTableModule was designed using the
-! dictionary implementation by Arjen Markus of the Flibs
-! collection of Fortran utilities.  This hash table works
-! like a dictionary.  There can be n number of character
-! strings and each string will be assigned a unique number
-! between 1 and n, allowing an efficient way to store a
-! unique integer index with a character string.
-
+!> @brief A chaining hash map for integers.
+!!
+!! Convenient for use as an index into arrays of arbitrary
+!! data type. The implementation is based on Arjen Markus'
+!! dictionary in the Flibs collection of Fortran utilities.
+!<
 module HashTableModule
 
   use KindModule, only: DP, I4B
@@ -22,268 +18,199 @@ module HashTableModule
   integer, parameter, private :: HASH_SIZE = 4993
   integer, parameter, private :: MULTIPLIER = 31
 
-  type :: ListDataType
+  type :: NodeType
     character(len=:), allocatable :: key
-    integer(I4B) :: index
-  end type ListDataType
-
-  type :: ListType
-    type(ListDataType) :: listdata
-    type(ListType), pointer :: next => null()
+    integer(I4B) :: value
+    type(NodeType), pointer :: next => null()
   contains
-    procedure :: add => listtype_add
-  end type ListType
+    procedure :: add => list_add
+  end type NodeType
 
-  type :: HashListType
-    type(ListType), pointer :: list => null()
-  end type HashListType
+  type :: BucketType
+    type(NodeType), pointer :: list => null()
+  end type BucketType
 
   type :: HashTableType
     private
-    type(HashListType), dimension(:), pointer :: table => null()
+    type(BucketType), pointer :: buckets(:) => null()
   contains
-    procedure :: add_entry
-    procedure :: get_elem
-    procedure :: get_index
+    procedure :: add => ht_add
+    procedure :: get => ht_get
+    procedure, private :: find_node
   end type HashTableType
 
 contains
 
-  subroutine hash_table_cr(ht)
-! ******************************************************************************
-! hash_table_cr -- public subroutine to create the hash table object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Create a hash table
+  subroutine hash_table_cr(map)
     ! -- dummy
-    type(HashTableType), pointer :: ht
+    type(HashTableType), pointer :: map
     ! -- local
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
-    !
+
     ! -- allocate
-    allocate (ht)
-    allocate (ht%table(HASH_SIZE))
-    !
-    ! -- nullify each list
+    allocate (map)
+    allocate (map%buckets(HASH_SIZE))
+
+    ! -- initialize nul buckets
     do i = 1, HASH_SIZE
-      ht%table(i)%list => null()
+      map%buckets(i)%list => null()
     end do
-    !
-    ! -- return
-    return
+
   end subroutine hash_table_cr
 
-  subroutine hash_table_da(ht)
-! ******************************************************************************
-! hash_table_da -- public subroutine to deallocate the hash table object
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Deallocate the hash table
+  subroutine hash_table_da(map)
     ! -- dummy
-    type(HashTableType), pointer :: ht
+    type(HashTableType), pointer :: map
     ! -- local
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
-    !
-    ! -- deallocate the list for each hash
-    do i = 1, size(ht%table)
-      if (associated(ht%table(i)%list)) then
-        call listtype_da(ht%table(i)%list)
+
+    ! -- deallocate each bucket
+    do i = 1, size(map%buckets)
+      if (associated(map%buckets(i)%list)) then
+        call list_da(map%buckets(i)%list)
       end if
     end do
-    !
-    ! -- deallocate the table and the hash table
-    deallocate (ht%table)
-    deallocate (ht)
-    !
-    ! -- return
-    return
+
+    ! -- deallocate bucket array and hash table
+    deallocate (map%buckets)
+    deallocate (map)
+
   end subroutine hash_table_da
 
-  subroutine add_entry(this, key, index)
-! ******************************************************************************
-! add_entry -- hash table method to add a key/index entry
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Associate the given key and value
+  subroutine ht_add(this, k, v)
     ! -- dummy
     class(HashTableType) :: this
-    character(len=*), intent(in) :: key
-    integer(I4B), intent(in) :: index
+    character(len=*), intent(in) :: k
+    integer(I4B), intent(in) :: v
     ! -- local
-    type(ListType), pointer :: elem
-    integer(I4B) :: ihash
-! ------------------------------------------------------------------------------
-    !
+    type(NodeType), pointer :: node
+    integer(I4B) :: h
+
     ! -- find the element corresponding to this key and replace index or
     !    get an unassociated elem that corresponds to this key
-    elem => this%get_elem(key)
-    !
+    node => this%find_node(k)
+
     ! -- replace index or create new entry
-    if (associated(elem)) then
-      elem%listdata%index = index
+    if (associated(node)) then
+      node%value = v
     else
-      ihash = hashfunc(trim(key))
-      if (associated(this%table(ihash)%list)) then
-        call this%table(ihash)%list%add(key, index)
+      h = hash(trim(k))
+      if (associated(this%buckets(h)%list)) then
+        call this%buckets(h)%list%add(k, v)
       else
-        call listtype_cr(this%table(ihash)%list, key, index)
+        call list_cr(this%buckets(h)%list, k, v)
       end if
     end if
-    !
-    ! -- return
-    return
-  end subroutine add_entry
-
-  function get_elem(this, key) result(elem)
-! ******************************************************************************
-! get_elem -- get the entry corresponding to this key
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+
+  end subroutine ht_add
+
+  !> @brief Find the node containing the given key
+  function find_node(this, k) result(node)
     ! -- dummy
-    class(HashTableType) :: this
-    character(len=*), intent(in) :: key
+    class(HashTableType) :: this !< the hash map
+    character(len=*), intent(in) :: k !< the key
     ! -- local
-    type(ListType), pointer :: elem
-    integer(I4B) :: ihash
-! ------------------------------------------------------------------------------
-    ihash = hashfunc(trim(key))
-    elem => this%table(ihash)%list
-    do while (associated(elem))
-      if (elem%listdata%key == key) then
+    type(NodeType), pointer :: node
+    integer(I4B) :: h
+
+    h = hash(trim(k))
+    node => this%buckets(h)%list
+
+    ! -- search bucket for node with matching key
+    do while (associated(node))
+      if (node%key == k) then
         exit
       else
-        elem => elem%next
+        node => node%next
       end if
     end do
-    !
-    ! -- return
-    return
-  end function get_elem
-
-  function get_index(this, key) result(index)
-! ******************************************************************************
-! get_index -- get the integer index that corresponds to this hash.
-!   Return a zero if key does not exist in hash table.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+
+  end function find_node
+
+  !> @brief Get the value for the given key if it exists, otherwise return zero.
+  function ht_get(this, k) result(v)
     ! -- dummy
-    class(HashTableType) :: this
-    character(len=*), intent(in) :: key
+    class(HashTableType) :: this !< the hash map
+    character(len=*), intent(in) :: k !< the key
     ! -- return
-    integer(I4B) :: index
+    integer(I4B) :: v
     ! -- local
-    type(ListType), pointer :: elem
-! ------------------------------------------------------------------------------
-    elem => this%get_elem(key)
-    if (associated(elem)) then
-      index = elem%listdata%index
+    type(NodeType), pointer :: node
+
+    node => this%find_node(k)
+    if (associated(node)) then
+      v = node%value
     else
-      index = 0
+      v = 0
     end if
-    !
-    ! -- return
-    return
-  end function get_index
-
-  subroutine listtype_cr(list, key, index)
-! ******************************************************************************
-! listtype_cr -- subroutine to create a list
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+
+  end function ht_get
+
+  !> @brief Create a list with the given key/value pair
+  subroutine list_cr(list, k, v)
     ! -- dummy
-    type(ListType), pointer :: list
-    character(len=*), intent(in) :: key
-    integer(I4B), intent(in) :: index
-! ------------------------------------------------------------------------------
+    type(NodeType), pointer :: list !< pointer to the list
+    character(len=*), intent(in) :: k !< the first key
+    integer(I4B), intent(in) :: v !< the first value
+
     allocate (list)
     list%next => null()
-    list%listdata%key = key
-    list%listdata%index = index
-    !
-    ! -- return
-    return
-  end subroutine listtype_cr
-
-  subroutine listtype_add(this, key, index)
-! ******************************************************************************
-! listtype_add -- method to add a key/index pair to a list
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    list%key = k
+    list%value = v
+
+  end subroutine list_cr
+
+  !> @brief Add a key/value pair to the list
+  subroutine list_add(this, k, v)
     ! -- dummy
-    class(ListType) :: this
-    character(len=*), intent(in) :: key
-    integer(I4B), intent(in) :: index
+    class(NodeType) :: this !< the list
+    character(len=*), intent(in) :: k !< the key
+    integer(I4B), intent(in) :: v !< the value
     ! -- local
-    type(ListType), pointer :: next
-! ------------------------------------------------------------------------------
+    type(NodeType), pointer :: next
+
     allocate (next)
-    next%listdata%key = key
-    next%listdata%index = index
+    next%key = k
+    next%value = v
     next%next => this%next
     this%next => next
-    !
-    ! -- return
-    return
-  end subroutine listtype_add
-
-  subroutine listtype_da(list)
-! ******************************************************************************
-! listtype_da -- subroutine to deallocate a list
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+
+  end subroutine list_add
+
+  !> @brief Deallocate the list
+  subroutine list_da(list)
     ! -- dummy
-    type(ListType), pointer, intent(in) :: list
+    type(NodeType), pointer, intent(in) :: list !< the list
     ! -- local
-    type(ListType), pointer :: current
-    type(ListType), pointer :: elem
-! ------------------------------------------------------------------------------
-    elem => list
-    do while (associated(elem))
-      current => elem
-      elem => current%next
-      deallocate (current)
+    type(NodeType), pointer :: curr
+    type(NodeType), pointer :: node
+
+    node => list
+    do while (associated(node))
+      curr => node
+      node => curr%next
+      deallocate (curr)
     end do
-    !
-    ! -- return
-    return
-  end subroutine listtype_da
-
-  function hashfunc(key) result(ihash)
-! ******************************************************************************
-! hashfunc -- function to convert key into an integer hash number
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+
+  end subroutine list_da
+
+  !> @brief Map a character string to an integer
+  function hash(k) result(h)
     ! -- dummy
-    character(len=*), intent(in) :: key
+    character(len=*), intent(in) :: k !< the key
     ! -- local
-    integer(I4B) :: ihash
+    integer(I4B) :: h
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
-    ihash = 0
-    do i = 1, len(key)
-      ihash = modulo(MULTIPLIER * ihash + ichar(key(i:i)), HASH_SIZE)
+
+    h = 0
+    do i = 1, len(k)
+      h = modulo(MULTIPLIER * h + ichar(k(i:i)), HASH_SIZE)
     end do
-    ihash = 1 + modulo(ihash - 1, HASH_SIZE)
-    !
-    ! -- return
-    return
-  end function hashfunc
+    h = 1 + modulo(h - 1, HASH_SIZE)
+
+  end function hash
 
 end module HashTableModule
diff --git a/src/Utilities/Idm/BoundInputContext.f90 b/src/Utilities/Idm/BoundInputContext.f90
new file mode 100644
index 00000000000..2afa3bdf041
--- /dev/null
+++ b/src/Utilities/Idm/BoundInputContext.f90
@@ -0,0 +1,561 @@
+!> @brief This module contains the BoundInputContextModule
+!!
+!! This module contains a type that stores and creates context
+!! relevant to stress package inputs.
+!!
+!<
+module BoundInputContextModule
+
+  use KindModule, only: DP, I4B, LGP
+  use ConstantsModule, only: DZERO, IZERO, LENAUXNAME, LENVARNAME, LENBOUNDNAME
+  use SimVariablesModule, only: errmsg
+  use SimModule, only: store_error, store_error_filename
+  use ModflowInputModule, only: ModflowInputType
+  use CharacterStringModule, only: CharacterStringType
+
+  implicit none
+  private
+  public :: BoundInputContextType
+
+  !> @brief derived type for boundary package input context
+  !!
+  !! This derived type defines input context used by dynamic package loaders.
+  !! Some variables (e.g. iprpak) in the type may have already been created
+  !! by a static loader whereas others (e.g. nboound) are created by this
+  !! type, updated by to dynamic loader, and accessed from the model package.
+  !!
+  !<
+  type :: BoundInputContextType
+    integer(I4B), pointer :: naux => null() !< number of auxiliary variables
+    integer(I4B), pointer :: maxbound => null() !< max list input records per period
+    integer(I4B), pointer :: inamedbound => null() !< are bound names optioned
+    integer(I4B), pointer :: iprpak => null() ! print input option
+    integer(I4B), pointer :: nbound => null() !< number of bounds in period
+    integer(I4B), pointer :: ncpl => null() !< number of cells per layer
+    type(CharacterStringType), dimension(:), pointer, &
+      contiguous :: auxname_cst => null() !< array of auxiliary names
+    type(CharacterStringType), dimension(:), pointer, &
+      contiguous :: boundname_cst => null() !< array of bound names
+    real(DP), dimension(:, :), pointer, &
+      contiguous :: auxvar => null() !< auxiliary variable array
+    integer(I4B), dimension(:), pointer, contiguous :: mshape => null() !< model shape
+    character(len=LENVARNAME), dimension(:), allocatable :: filtcols !< list input in scope columns
+    integer(I4B) :: nfiltcol !< list input number of in scope columns
+    logical(LGP) :: readasarrays !< grid or list based input
+    type(ModflowInputType) :: mf6_input !< description of input
+  contains
+    procedure :: init => bndctx_init
+    procedure :: create_context
+    procedure :: enable
+    procedure :: bound_params_allocate
+    procedure :: param_init
+    procedure :: allocate_read_state_var
+    procedure :: destroy => bndctx_destroy
+    procedure :: set_filtered_cols
+    procedure :: filtered_cols
+  end type BoundInputContextType
+
+contains
+
+  !> @brief initialize boundary input context
+  !!
+  !<
+  subroutine bndctx_init(this, mf6_input, readasarrays)
+    ! -- modules
+    ! -- dummy
+    class(BoundInputContextType) :: this
+    type(ModflowInputType), intent(in) :: mf6_input
+    logical(LGP), intent(in) :: readasarrays
+    !
+    this%mf6_input = mf6_input
+    this%readasarrays = readasarrays
+    !
+    ! -- create the dynamic package input context
+    call this%create_context()
+    !
+    ! -- determine in scope list input columns
+    if (.not. readasarrays) then
+      call this%set_filtered_cols()
+    end if
+    !
+    ! --return
+    return
+  end subroutine bndctx_init
+
+  !> @brief create boundary input context
+  !!
+  !<
+  subroutine create_context(this)
+    ! -- modules
+    use MemoryManagerModule, only: mem_allocate, mem_setptr, get_isize
+    use MemoryManagerExtModule, only: mem_set_value
+    ! -- dummy
+    class(BoundInputContextType) :: this
+    integer(I4B), dimension(:, :), pointer, contiguous :: cellid => null()
+    logical(LGP) :: found
+    !
+    ! -- set pointers to defined scalars
+    call mem_setptr(this%naux, 'NAUX', this%mf6_input%mempath)
+    !
+    ! -- allocate memory managed scalars
+    call mem_allocate(this%nbound, 'NBOUND', this%mf6_input%mempath)
+    call mem_allocate(this%ncpl, 'NCPL', this%mf6_input%mempath)
+    !
+    ! -- internally allocate package optional scalars
+    allocate (this%maxbound)
+    allocate (this%inamedbound)
+    allocate (this%iprpak)
+    !
+    ! -- initialize allocated and internal scalars
+    this%nbound = 0
+    this%ncpl = 0
+    this%maxbound = 0
+    this%inamedbound = 0
+    this%iprpak = 0
+    this%nfiltcol = 0
+    !
+    ! -- update optional scalars
+    call mem_set_value(this%inamedbound, 'BOUNDNAMES', this%mf6_input%mempath, &
+                       found)
+    call mem_set_value(this%maxbound, 'MAXBOUND', this%mf6_input%mempath, found)
+    call mem_set_value(this%iprpak, 'IPRPAK', this%mf6_input%mempath, found)
+    !
+    ! -- set pointers to defined arrays
+    call mem_setptr(this%mshape, 'MODEL_SHAPE', &
+                    this%mf6_input%component_mempath)
+    !
+    ! -- update ncpl as shape is known
+    if (size(this%mshape) == 2) then
+      this%ncpl = this%mshape(2)
+    else if (size(this%mshape) == 3) then
+      this%ncpl = this%mshape(2) * this%mshape(3)
+    end if
+    !
+    ! -- set auxname_cst and iauxmultcol
+    if (this%naux > 0) then
+      call mem_setptr(this%auxname_cst, 'AUXILIARY', this%mf6_input%mempath)
+    else
+      call mem_allocate(this%auxname_cst, LENAUXNAME, 0, &
+                        'AUXILIARY', this%mf6_input%mempath)
+    end if
+    !
+    ! -- allocate cellid if this is not list input
+    if (this%readasarrays) then
+      call mem_allocate(cellid, 0, 0, 'CELLID', this%mf6_input%mempath)
+    end if
+    !
+    ! -- return
+    return
+  end subroutine create_context
+
+  !> @brief enable bound input context
+  !!
+  !! This routine should be invoked after the loader allocates dynamic
+  !! input params. This routine will assign pointers to arrays if they
+  !! have been allocated and allocate the arrays if not.
+  !!
+  !<
+  subroutine enable(this)
+    ! -- modules
+    use MemoryManagerModule, only: mem_allocate, mem_setptr, get_isize
+    use MemoryManagerExtModule, only: mem_set_value
+    ! -- dummy
+    class(BoundInputContextType) :: this
+    ! -- local
+    !
+    ! -- allocate or set pointer to BOUNDNAME
+    if (this%inamedbound == 0) then
+      call mem_allocate(this%boundname_cst, LENBOUNDNAME, 0, &
+                        'BOUNDNAME', this%mf6_input%mempath)
+      !
+    else
+      call mem_setptr(this%boundname_cst, 'BOUNDNAME', this%mf6_input%mempath)
+    end if
+    !
+    ! -- allocate or set pointer to AUXVAR
+    if (this%naux == 0) then
+      call mem_allocate(this%auxvar, 0, 0, 'AUXVAR', this%mf6_input%mempath)
+      !
+    else
+      call mem_setptr(this%auxvar, 'AUXVAR', this%mf6_input%mempath)
+    end if
+    !
+    ! -- return
+    return
+  end subroutine enable
+
+  !> @brief allocate a read state variable
+  !!
+  !! Create and set a read state variable, e.g. 'INRECHARGE',
+  !! which are updated per iper load as follows:
+  !! -1: unset, not in use
+  !!  0: not read in most recent period block
+  !!  1: numeric input read in most recent period block
+  !!  2: time series input read in most recent period block
+  !!
+  !<
+  function allocate_read_state_var(this, mf6varname) result(varname)
+    ! -- modules
+    use MemoryManagerModule, only: mem_setptr, mem_allocate
+    ! -- dummy
+    class(BoundInputContextType) :: this
+    character(len=*), intent(in) :: mf6varname
+    ! -- locals
+    character(len=LENVARNAME) :: varname
+    integer(I4B) :: ilen
+    integer(I4B), pointer :: intvar
+    character(len=2) :: prefix = 'IN'
+    !
+    ! -- assign first column as the block number
+    ilen = len_trim(mf6varname)
+    !
+    if (ilen > (LENVARNAME - len(prefix))) then
+      varname = prefix//mf6varname(1:(LENVARNAME - len(prefix)))
+    else
+      varname = prefix//trim(mf6varname)
+    end if
+    !
+    call mem_allocate(intvar, varname, this%mf6_input%mempath)
+    intvar = -1
+    !
+    ! -- return
+    return
+  end function allocate_read_state_var
+
+  !> @brief allocate dfn period block parameters
+  !!
+  !! Currently supports numeric (i.e. array based) params
+  !!
+  !<
+  subroutine bound_params_allocate(this, sourcename)
+    ! -- modules
+    use MemoryManagerModule, only: mem_allocate
+    use InputDefinitionModule, only: InputParamDefinitionType
+    ! -- dummy
+    class(BoundInputContextType) :: this
+    character(len=*) :: sourcename
+    type(InputParamDefinitionType), pointer :: idt
+    integer(I4B), dimension(:), pointer, contiguous :: int1d
+    real(DP), dimension(:), pointer, contiguous :: dbl1d
+    real(DP), dimension(:, :), pointer, contiguous :: dbl2d
+    integer(I4B) :: iparam, n, m
+    !
+    ! -- list input allocates via structarray
+    if (.not. this%readasarrays) then
+      call store_error('Programming error. (IDM) Bound context unsupported &
+                       &list based param allocation.')
+      call store_error_filename(sourcename)
+    end if
+    !
+    ! -- allocate dfn input params
+    do iparam = 1, size(this%mf6_input%param_dfns)
+      !
+      ! -- assign param definition pointer
+      idt => this%mf6_input%param_dfns(iparam)
+      !
+      if (idt%blockname == 'PERIOD') then
+        !
+        ! allocate based on dfn datatype
+        select case (idt%datatype)
+        case ('INTEGER1D')
+          !
+          call mem_allocate(int1d, this%ncpl, idt%mf6varname, &
+                            this%mf6_input%mempath)
+          !
+          do n = 1, this%ncpl
+            int1d(n) = IZERO
+          end do
+          !
+        case ('DOUBLE1D')
+          !
+          call mem_allocate(dbl1d, this%ncpl, idt%mf6varname, &
+                            this%mf6_input%mempath)
+          !
+          do n = 1, this%ncpl
+            dbl1d(n) = DZERO
+          end do
+          !
+        case ('DOUBLE2D')
+          !
+          call mem_allocate(dbl2d, this%naux, this%ncpl, &
+                            idt%mf6varname, this%mf6_input%mempath)
+          !
+          do m = 1, this%ncpl
+            do n = 1, this%naux
+              dbl2d(n, m) = DZERO
+            end do
+          end do
+          !
+        case default
+          call store_error('Programming error. (IDM) Bound context unsupported &
+                           &data type allocation for param='//trim(idt%tagname))
+          call store_error_filename(sourcename)
+        end select
+        !
+      end if
+    end do
+    !
+    ! -- enable
+    call this%enable()
+    !
+    ! -- return
+    return
+  end subroutine bound_params_allocate
+
+  subroutine param_init(this, datatype, varname, mempath, sourcename)
+    ! -- modules
+    use MemoryManagerModule, only: mem_setptr
+    ! -- dummy
+    class(BoundInputContextType) :: this
+    character(len=*), intent(in) :: datatype
+    character(len=*), intent(in) :: varname
+    character(len=*), intent(in) :: mempath
+    character(len=*), intent(in) :: sourcename
+    ! -- locals
+    integer(I4B), dimension(:), pointer, contiguous :: int1d
+    real(DP), dimension(:), pointer, contiguous :: dbl1d
+    real(DP), dimension(:, :), pointer, contiguous :: dbl2d
+    type(CharacterStringType), dimension(:), pointer, &
+      contiguous :: charstr1d => null()
+    integer(I4B) :: n, m
+    !
+    select case (datatype)
+    case ('INTEGER1D')
+      !
+      call mem_setptr(int1d, varname, mempath)
+      do n = 1, this%ncpl
+        int1d(n) = IZERO
+      end do
+      !
+    case ('DOUBLE1D')
+      !
+      call mem_setptr(dbl1d, varname, mempath)
+      do n = 1, this%ncpl
+        dbl1d(n) = DZERO
+      end do
+      !
+    case ('DOUBLE2D')
+      !
+      call mem_setptr(dbl2d, varname, mempath)
+      do m = 1, this%ncpl
+        do n = 1, this%naux
+          dbl2d(n, m) = DZERO
+        end do
+      end do
+      !
+    case ('CHARSTR1D')
+      !
+      call mem_setptr(charstr1d, varname, mempath)
+      do n = 1, size(charstr1d)
+        charstr1d(n) = ''
+      end do
+      !
+    case default
+      !
+      call store_error('Programming error. (IDM) Bound context unsupported &
+                       &data type initialization for param='//trim(varname))
+      call store_error_filename(sourcename)
+      !
+    end select
+    !
+    ! -- return
+    return
+  end subroutine param_init
+
+  !> @brief destroy boundary input context
+  !!
+  !<
+  subroutine bndctx_destroy(this)
+    ! -- modules
+    ! -- dummy
+    class(BoundInputContextType) :: this
+    !
+    ! -- deallocate
+    deallocate (this%maxbound)
+    deallocate (this%inamedbound)
+    deallocate (this%iprpak)
+    !
+    ! -- nullify
+    nullify (this%naux)
+    nullify (this%nbound)
+    nullify (this%ncpl)
+    nullify (this%maxbound)
+    nullify (this%inamedbound)
+    nullify (this%iprpak)
+    nullify (this%auxname_cst)
+    nullify (this%boundname_cst)
+    nullify (this%auxvar)
+    nullify (this%mshape)
+    !
+    deallocate (this%filtcols)
+    !
+    ! --return
+    return
+  end subroutine bndctx_destroy
+
+  !> @brief create array of in scope list input columns
+  !!
+  !! Filter the recarray description of list input parameters
+  !! to determine which columns are to be read in this run.
+  !<
+  subroutine set_filtered_cols(this)
+    ! -- modules
+    use InputDefinitionModule, only: InputParamDefinitionType
+    use DefinitionSelectModule, only: get_aggregate_definition_type
+    use ArrayHandlersModule, only: expandarray
+    use InputOutputModule, only: parseline
+    ! -- dummy
+    class(BoundInputContextType) :: this
+    ! -- local
+    type(InputParamDefinitionType), pointer :: ra_idt
+    character(len=:), allocatable :: parse_str
+    character(len=LENVARNAME), dimension(:), allocatable :: dfncols
+    integer(I4B), dimension(:), allocatable :: idxs
+    integer(I4B) :: dfnncol, icol, keepcnt
+    logical(LGP) :: keep
+    !
+    ! -- initialize
+    keepcnt = 0
+    !
+    ! -- get aggregate param definition for period block
+    ra_idt => &
+      get_aggregate_definition_type(this%mf6_input%aggregate_dfns, &
+                                    this%mf6_input%component_type, &
+                                    this%mf6_input%subcomponent_type, &
+                                    'PERIOD')
+    !
+    ! -- split recarray definition
+    parse_str = trim(ra_idt%datatype)//' '
+    call parseline(parse_str, dfnncol, dfncols)
+    !
+    ! -- determine which columns are in scope
+    do icol = 1, dfnncol
+      !
+      keep = .false.
+      !
+      if (dfncols(icol) == 'RECARRAY') then
+        ! no-op
+      else if (dfncols(icol) == 'AUX') then
+        if (this%naux > 0) then
+          keep = .true.
+        end if
+      else if (dfncols(icol) == 'BOUNDNAME') then
+        if (this%inamedbound /= 0) then
+          keep = .true.
+        end if
+      else
+        keep = pkg_param_in_scope(this%mf6_input, dfncols(icol))
+      end if
+      !
+      if (keep) then
+        keepcnt = keepcnt + 1
+        call expandarray(idxs)
+        idxs(keepcnt) = icol
+      end if
+    end do
+    !
+    ! -- update nfiltcol
+    this%nfiltcol = keepcnt
+    !
+    ! -- allocate filtcols
+    allocate (this%filtcols(this%nfiltcol))
+    !
+    ! -- set filtcols
+    do icol = 1, this%nfiltcol
+      this%filtcols(icol) = dfncols(idxs(icol))
+    end do
+    !
+    ! -- cleanup
+    deallocate (dfncols)
+    deallocate (idxs)
+    deallocate (parse_str)
+    !
+    ! -- return
+    return
+  end subroutine set_filtered_cols
+
+  !> @brief allocate and set input array to filtered param set
+  !!
+  !<
+  subroutine filtered_cols(this, cols, ncol)
+    ! -- modules
+    ! -- dummy
+    class(BoundInputContextType) :: this
+    character(len=LENVARNAME), dimension(:), allocatable, &
+      intent(inout) :: cols
+    integer(I4B), intent(inout) :: ncol
+    integer(I4B) :: n
+    !
+    if (allocated(cols)) deallocate (cols)
+    !
+    ncol = this%nfiltcol
+    !
+    allocate (cols(ncol))
+    !
+    do n = 1, ncol
+      cols(n) = this%filtcols(n)
+    end do
+    !
+    ! -- return
+    return
+  end subroutine filtered_cols
+
+  !> @brief determine if input param is in scope for a package
+  !!
+  !<
+  function pkg_param_in_scope(mf6_input, tagname) result(in_scope)
+    ! -- modules
+    use MemoryManagerModule, only: get_isize, mem_setptr
+    use InputDefinitionModule, only: InputParamDefinitionType
+    use DefinitionSelectModule, only: get_param_definition_type
+    ! -- dummy
+    type(ModflowInputType), intent(in) :: mf6_input
+    character(len=*), intent(in) :: tagname
+    ! -- return
+    logical(LGP) :: in_scope
+    ! -- locals
+    type(InputParamDefinitionType), pointer :: idt
+    integer(I4B) :: pdim_isize, popt_isize
+    integer(I4B), pointer :: pdim
+    !
+    ! -- initialize
+    in_scope = .false.
+    !
+    idt => get_param_definition_type(mf6_input%param_dfns, &
+                                     mf6_input%component_type, &
+                                     mf6_input%subcomponent_type, &
+                                     'PERIOD', tagname, '')
+    !
+    if (idt%required) then
+      ! -- required params always included
+      in_scope = .true.
+    else
+      !
+      ! -- package specific logic to determine if input params to be read
+      select case (mf6_input%subcomponent_type)
+      case ('EVT')
+        !
+        if (tagname == 'PXDP' .or. tagname == 'PETM') then
+          call get_isize('NSEG', mf6_input%mempath, pdim_isize)
+          if (pdim_isize > 0) then
+            call mem_setptr(pdim, 'NSEG', mf6_input%mempath)
+            if (pdim > 1) then
+              in_scope = .true.
+            end if
+          end if
+        else if (tagname == 'PETM0') then
+          call get_isize('SURFRATESPEC', mf6_input%mempath, popt_isize)
+          if (popt_isize > 0) then
+            in_scope = .true.
+          end if
+        end if
+        !
+      case default
+      end select
+    end if
+    !
+    ! -- return
+    return
+  end function pkg_param_in_scope
+
+end module BoundInputContextModule
diff --git a/src/Utilities/Idm/IdmLoad.f90 b/src/Utilities/Idm/IdmLoad.f90
new file mode 100644
index 00000000000..b7c95f238dd
--- /dev/null
+++ b/src/Utilities/Idm/IdmLoad.f90
@@ -0,0 +1,676 @@
+!> @brief This module contains the IdmLoadModule
+!!
+!! This module contains routines for managing static
+!! and dynamic input loading for supported sources.
+!!
+!<
+module IdmLoadModule
+
+  use KindModule, only: DP, I4B, LGP
+  use SimVariablesModule, only: errmsg
+  use ConstantsModule, only: LINELENGTH, LENMEMPATH, LENMODELNAME, &
+                             LENEXCHANGENAME, LENCOMPONENTNAME
+  use SimModule, only: store_error, store_error_filename
+  use ListModule, only: ListType
+  use InputLoadTypeModule, only: StaticPkgLoadBaseType, &
+                                 DynamicPkgLoadBaseType, &
+                                 ModelDynamicPkgsType
+  use InputDefinitionModule, only: InputParamDefinitionType
+  use ModflowInputModule, only: ModflowInputType, getModflowInput
+
+  implicit none
+  private
+  public :: simnam_load
+  public :: load_models
+  public :: load_exchanges
+  public :: idm_df
+  public :: idm_rp
+  public :: idm_ad
+  public :: idm_da
+
+  type(ListType) :: model_dynamic_pkgs
+
+contains
+
+  !> @brief advance package dynamic data for period steps
+  !<
+  subroutine idm_df()
+    use InputLoadTypeModule, only: GetDynamicModelFromList
+    class(ModelDynamicPkgsType), pointer :: model_dynamic_input
+    integer(I4B) :: n
+    !
+    do n = 1, model_dynamic_pkgs%Count()
+      model_dynamic_input => GetDynamicModelFromList(model_dynamic_pkgs, n)
+      call model_dynamic_input%df()
+    end do
+    !
+    ! -- return
+    return
+  end subroutine idm_df
+
+  !> @brief load package dynamic data for period
+  !<
+  subroutine idm_rp()
+    use InputLoadTypeModule, only: GetDynamicModelFromList
+    class(ModelDynamicPkgsType), pointer :: model_dynamic_input
+    integer(I4B) :: n
+    !
+    do n = 1, model_dynamic_pkgs%Count()
+      model_dynamic_input => GetDynamicModelFromList(model_dynamic_pkgs, n)
+      call model_dynamic_input%rp()
+    end do
+    !
+    ! -- return
+    return
+  end subroutine idm_rp
+
+  !> @brief advance package dynamic data for period steps
+  !<
+  subroutine idm_ad()
+    use InputLoadTypeModule, only: GetDynamicModelFromList
+    class(ModelDynamicPkgsType), pointer :: model_dynamic_input
+    integer(I4B) :: n
+    !
+    do n = 1, model_dynamic_pkgs%Count()
+      model_dynamic_input => GetDynamicModelFromList(model_dynamic_pkgs, n)
+      call model_dynamic_input%ad()
+    end do
+    !
+    ! -- return
+    return
+  end subroutine idm_ad
+
+  !> @brief idm deallocate routine
+  !<
+  subroutine idm_da(iout)
+    use SimVariablesModule, only: idm_context
+    use MemoryManagerModule, only: mem_setptr
+    use MemoryHelperModule, only: create_mem_path, split_mem_path
+    use MemoryManagerExtModule, only: memorylist_remove
+    use CharacterStringModule, only: CharacterStringType
+    integer(I4B), intent(in) :: iout
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: mempaths
+    character(len=LENCOMPONENTNAME) :: exg_comp, exg_subcomp
+    character(len=LENMEMPATH) :: input_mempath, mempath
+    integer(I4B) :: n
+    !
+    ! -- deallocate dynamic loaders
+    call dynamic_da(iout)
+    !
+    ! -- deallocate EXG mempaths
+    input_mempath = create_mem_path('SIM', 'NAM', idm_context)
+    call mem_setptr(mempaths, 'EXGMEMPATHS', input_mempath)
+    do n = 1, size(mempaths)
+      mempath = mempaths(n)
+      if (mempath /= '') then
+        call split_mem_path(mempath, exg_comp, exg_subcomp)
+        call memorylist_remove(exg_comp, exg_subcomp, idm_context)
+      end if
+    end do
+    !
+    ! -- return
+    return
+  end subroutine idm_da
+
+  !> @brief load an integrated model package from supported source
+  !<
+  subroutine model_pkg_load(model_pkg_inputs, itype, ipkg, iout)
+    use ModelPackageInputsModule, only: ModelPackageInputsType
+    use SourceLoadModule, only: create_input_loader
+    type(ModelPackageInputsType), intent(in) :: model_pkg_inputs
+    integer(I4B), intent(in) :: itype
+    integer(I4B), intent(in) :: ipkg
+    integer(I4B), intent(in) :: iout
+    class(StaticPkgLoadBaseType), pointer :: static_loader
+    class(DynamicPkgLoadBaseType), pointer :: dynamic_loader
+    class(ModelDynamicPkgsType), pointer :: dynamic_pkgs => null()
+    !
+    ! -- create model package loader
+    static_loader => &
+      create_input_loader(model_pkg_inputs%component_type, &
+                          model_pkg_inputs%pkglist(itype)%subcomponent_type, &
+                          model_pkg_inputs%modelname, &
+                          model_pkg_inputs%pkglist(itype)%pkgnames(ipkg), &
+                          model_pkg_inputs%pkglist(itype)%pkgtype, &
+                          model_pkg_inputs%pkglist(itype)%filenames(ipkg), &
+                          model_pkg_inputs%modelfname)
+    !
+    ! -- load static input and set dynamic loader
+    dynamic_loader => static_loader%load(iout)
+    !
+    if (associated(dynamic_loader)) then
+      !
+      ! -- set pointer to model dynamic packages list
+      dynamic_pkgs => dynamic_model_pkgs(model_pkg_inputs%modelname, &
+                                         static_loader%component_input_name, &
+                                         iout)
+      !
+      ! -- add dynamic pkg loader to list
+      call dynamic_pkgs%add(dynamic_loader)
+      !
+    end if
+    !
+    ! -- cleanup
+    call static_loader%destroy()
+    deallocate (static_loader)
+    !
+    ! -- return
+    return
+  end subroutine model_pkg_load
+
+  !> @brief load integrated model package files
+  !<
+  subroutine load_model_pkgs(model_pkg_inputs, iout)
+    use ModelPackageInputsModule, only: ModelPackageInputsType
+    use SourceLoadModule, only: open_source_file
+    use IdmDfnSelectorModule, only: idm_integrated
+    type(ModelPackageInputsType), intent(inout) :: model_pkg_inputs
+    integer(i4B), intent(in) :: iout
+    integer(I4B) :: itype, ipkg
+    !
+    ! -- load package instances by type
+    do itype = 1, size(model_pkg_inputs%pkglist)
+      !
+      ! -- load package instances
+      do ipkg = 1, model_pkg_inputs%pkglist(itype)%pnum
+
+        if (idm_integrated(model_pkg_inputs%component_type, &
+                           model_pkg_inputs%pkglist(itype)%subcomponent_type)) &
+          then
+          !
+          ! -- only load if model pkg can read from input context
+          call model_pkg_load(model_pkg_inputs, itype, ipkg, iout)
+        else
+          !
+          ! -- open input file for package parser
+          model_pkg_inputs%pkglist(itype)%inunits(ipkg) = &
+            open_source_file(model_pkg_inputs%pkglist(itype)%pkgtype, &
+                             model_pkg_inputs%pkglist(itype)%filenames(ipkg), &
+                             model_pkg_inputs%modelfname, iout)
+        end if
+      end do
+    end do
+    !
+    ! -- return
+    return
+  end subroutine load_model_pkgs
+
+  !> @brief load model namfiles and model package files
+  !<
+  subroutine load_models(model_loadmask, iout)
+    ! -- modules
+    use MemoryHelperModule, only: create_mem_path
+    use MemoryManagerModule, only: mem_setptr
+    use CharacterStringModule, only: CharacterStringType
+    use SimVariablesModule, only: idm_context
+    use ModelPackageInputsModule, only: ModelPackageInputsType
+    use SourceCommonModule, only: idm_component_type
+    use SourceLoadModule, only: load_modelnam
+    ! -- dummy
+    integer(I4B), dimension(:), intent(in) :: model_loadmask
+    integer(I4B), intent(in) :: iout
+    ! -- locals
+    character(len=LENMEMPATH) :: input_mempath
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: mtypes !< model types
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: mfnames !< model file names
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: mnames !< model names
+    character(len=LINELENGTH) :: mtype, mfname
+    character(len=LENMODELNAME) :: mname
+    type(ModelPackageInputsType), allocatable :: model_pkg_inputs
+    integer(I4B) :: n
+    !
+    ! -- set input memory path
+    input_mempath = create_mem_path('SIM', 'NAM', idm_context)
+    !
+    ! -- set pointers to input context model attribute arrays
+    call mem_setptr(mtypes, 'MTYPE', input_mempath)
+    call mem_setptr(mfnames, 'MFNAME', input_mempath)
+    call mem_setptr(mnames, 'MNAME', input_mempath)
+    !
+    do n = 1, size(mtypes)
+      !
+      ! -- attributes for this model
+      mtype = mtypes(n)
+      mfname = mfnames(n)
+      mname = mnames(n)
+      !
+      ! -- load specified model inputs
+      if (model_loadmask(n) > 0) then
+        !
+        ! -- load model nam file
+        call load_modelnam(mtype, mfname, mname, iout)
+        !
+        ! -- create description of model packages
+        allocate (model_pkg_inputs)
+        call model_pkg_inputs%init(mtype, mfname, mname, iout)
+        !
+        ! -- load packages
+        call load_model_pkgs(model_pkg_inputs, iout)
+        !
+        ! -- publish pkg info to input context
+        call model_pkg_inputs%memload()
+        !
+        ! -- cleanup
+        call model_pkg_inputs%destroy()
+        deallocate (model_pkg_inputs)
+      end if
+    end do
+    !
+    ! -- return
+    return
+  end subroutine load_models
+
+  !> @brief load exchange files
+  !<
+  subroutine load_exchanges(model_loadmask, iout)
+    ! -- modules
+    use MemoryHelperModule, only: create_mem_path
+    use MemoryManagerModule, only: mem_setptr, mem_allocate, &
+                                   mem_deallocate, get_isize
+    use CharacterStringModule, only: CharacterStringType
+    use SimVariablesModule, only: idm_context, simfile
+    use SourceCommonModule, only: idm_subcomponent_type, ifind_charstr
+    use SourceLoadModule, only: create_input_loader, remote_model_ndim
+    ! -- dummy
+    integer(I4B), dimension(:), intent(in) :: model_loadmask
+    integer(I4B), intent(in) :: iout
+    ! -- locals
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: etypes !< exg types
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: efiles !< exg file names
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: emnames_a !< model a names
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: emnames_b !< model b names
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: emempaths !< exg mempaths
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: mtypes !< model types
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: mfnames !< model file names
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: mnames !< model names
+    character(len=LENMEMPATH) :: input_mempath, mempath
+    integer(I4B), pointer :: exgid, ncelldim
+    character(len=LINELENGTH) :: exgtype, efname, mfname
+    character(len=LENMODELNAME) :: mname1, mname2, mname
+    character(len=LENCOMPONENTNAME) :: sc_type, sc_name, mtype
+    class(StaticPkgLoadBaseType), pointer :: static_loader
+    class(DynamicPkgLoadBaseType), pointer :: dynamic_loader
+    integer(I4B) :: n, m1_idx, m2_idx, irem, isize
+    !
+    ! -- set input memory path
+    input_mempath = create_mem_path('SIM', 'NAM', idm_context)
+    !
+    ! -- set pointers to input context exg and model attribute arrays
+    call mem_setptr(etypes, 'EXGTYPE', input_mempath)
+    call mem_setptr(efiles, 'EXGFILE', input_mempath)
+    call mem_setptr(emnames_a, 'EXGMNAMEA', input_mempath)
+    call mem_setptr(emnames_b, 'EXGMNAMEB', input_mempath)
+    call mem_setptr(mtypes, 'MTYPE', input_mempath)
+    call mem_setptr(mfnames, 'MFNAME', input_mempath)
+    call mem_setptr(mnames, 'MNAME', input_mempath)
+    !
+    ! -- allocate mempaths array for exchanges
+    call mem_allocate(emempaths, LENMEMPATH, size(etypes), 'EXGMEMPATHS', &
+                      input_mempath)
+    !
+    ! -- load exchanges for local models
+    do n = 1, size(etypes)
+      !
+      ! -- attributes for this exchange
+      exgtype = etypes(n)
+      efname = efiles(n)
+      mname1 = emnames_a(n)
+      mname2 = emnames_b(n)
+      !
+      ! initialize mempath as no path
+      emempaths(n) = ''
+      irem = 0
+      !
+      ! -- set indexes for exchange model names
+      m1_idx = ifind_charstr(mnames, mname1)
+      m2_idx = ifind_charstr(mnames, mname2)
+      !
+      if (m1_idx <= 0 .or. m2_idx <= 0) then
+        errmsg = 'Exchange has invalid (unrecognized) model name(s):'
+        if (m1_idx <= 0) errmsg = trim(errmsg)//' '//trim(mname1)
+        if (m2_idx <= 0) errmsg = trim(errmsg)//' '//trim(mname2)
+        call store_error(errmsg)
+        call store_error_filename(simfile)
+      end if
+      !
+      ! -- load the exchange input if either model local
+      if (model_loadmask(m1_idx) > 0 .or. model_loadmask(m2_idx) > 0) then
+        !
+        ! -- set index if either model is remote
+        if (model_loadmask(m1_idx) == 0) then
+          irem = m1_idx
+        else if (model_loadmask(m2_idx) == 0) then
+          irem = m2_idx
+        end if
+        !
+        ! -- allocate and set remote model NCELLDIM
+        if (irem > 0) then
+          mtype = mtypes(irem)
+          mfname = mfnames(irem)
+          mname = mnames(irem)
+          mempath = create_mem_path(component=mname, context=idm_context)
+          call get_isize('NCELLDIM', mempath, isize)
+          if (isize < 0) then
+            call mem_allocate(ncelldim, 'NCELLDIM', mempath)
+            ncelldim = remote_model_ndim(mtype, mfname)
+          else
+            call mem_setptr(ncelldim, 'NCELLDIM', mempath)
+          end if
+        else
+          nullify (ncelldim)
+        end if
+        !
+        ! -- set subcomponent strings
+        sc_type = trim(idm_subcomponent_type('EXG', exgtype))
+        write (sc_name, '(a,i0)') trim(sc_type)//'_', n
+        !
+        ! -- create and set exchange mempath
+        mempath = create_mem_path('EXG', sc_name, idm_context)
+        emempaths(n) = mempath
+        !
+        ! -- allocate and set exgid
+        call mem_allocate(exgid, 'EXGID', mempath)
+        exgid = n
+        !
+        ! -- create exchange loader
+        static_loader => create_input_loader('EXG', sc_type, 'EXG', sc_name, &
+                                             exgtype, efname, simfile)
+        ! -- load static input
+        dynamic_loader => static_loader%load(iout)
+        !
+        if (associated(dynamic_loader)) then
+          errmsg = 'IDM unimplemented. Dynamic Exchanges not supported.'
+          call store_error(errmsg)
+          call store_error_filename(efname)
+        else
+          call static_loader%destroy()
+          deallocate (static_loader)
+        end if
+        !
+      end if
+      !
+    end do
+    !
+    ! -- clean up temporary NCELLDIM for remote models
+    do n = 1, size(mnames)
+      if (model_loadmask(n) == 0) then
+        mname = mnames(n)
+        mempath = create_mem_path(component=mname, context=idm_context)
+        call get_isize('NCELLDIM', mempath, isize)
+        if (isize > 0) then
+          call mem_setptr(ncelldim, 'NCELLDIM', mempath)
+          call mem_deallocate(ncelldim)
+        end if
+      end if
+    end do
+    !
+    ! -- return
+    return
+  end subroutine load_exchanges
+
+  !> @brief MODFLOW 6 mfsim.nam input load routine
+  !<
+  subroutine simnam_load(paramlog)
+    use SourceLoadModule, only: load_simnam
+    integer(I4B), intent(inout) :: paramlog
+    !
+    ! -- load sim nam file
+    call load_simnam()
+    !
+    ! -- allocate any unallocated simnam params
+    call simnam_allocate()
+    !
+    ! -- read and set input parameter logging keyword
+    paramlog = input_param_log()
+    !
+    ! -- memload summary info
+    call simnam_load_dim()
+    !
+    ! --return
+    return
+  end subroutine simnam_load
+
+  !> @brief retrieve list of model dynamic loaders
+  !<
+  function dynamic_model_pkgs(modelname, modelfname, iout) &
+    result(model_dynamic_input)
+    use InputLoadTypeModule, only: AddDynamicModelToList, GetDynamicModelFromList
+    character(len=*), intent(in) :: modelname
+    character(len=*), intent(in) :: modelfname
+    integer(I4B), intent(in) :: iout
+    class(ModelDynamicPkgsType), pointer :: model_dynamic_input
+    class(ModelDynamicPkgsType), pointer :: temp
+    integer(I4B) :: id
+    !
+    ! -- initialize
+    nullify (model_dynamic_input)
+    !
+    ! -- assign model loader object if found
+    do id = 1, model_dynamic_pkgs%Count()
+      temp => GetDynamicModelFromList(model_dynamic_pkgs, id)
+      if (temp%modelname == modelname) then
+        model_dynamic_input => temp
+        exit
+      end if
+    end do
+    !
+    ! -- create if not found
+    if (.not. associated(model_dynamic_input)) then
+      allocate (model_dynamic_input)
+      call model_dynamic_input%init(modelname, modelfname, iout)
+      call AddDynamicModelToList(model_dynamic_pkgs, model_dynamic_input)
+    end if
+    !
+    ! -- return
+    return
+  end function dynamic_model_pkgs
+
+  !> @brief deallocate all model dynamic loader collections
+  !<
+  subroutine dynamic_da(iout)
+    use InputLoadTypeModule, only: GetDynamicModelFromList
+    integer(I4B), intent(in) :: iout
+    class(ModelDynamicPkgsType), pointer :: model_dynamic_input
+    integer(I4B) :: n
+    !
+    do n = 1, model_dynamic_pkgs%Count()
+      model_dynamic_input => GetDynamicModelFromList(model_dynamic_pkgs, n)
+      call model_dynamic_input%destroy()
+      deallocate (model_dynamic_input)
+      nullify (model_dynamic_input)
+    end do
+    !
+    call model_dynamic_pkgs%Clear()
+    !
+    ! -- return
+    return
+  end subroutine dynamic_da
+
+  !> @brief return sim input context PRINT_INTPUT value
+  !<
+  function input_param_log() result(paramlog)
+    use MemoryHelperModule, only: create_mem_path
+    use MemoryManagerModule, only: mem_setptr
+    use SimVariablesModule, only: idm_context
+    character(len=LENMEMPATH) :: simnam_mempath
+    integer(I4B) :: paramlog
+    integer(I4B), pointer :: p
+    !
+    ! -- read and set input value of PRINT_INPUT
+    simnam_mempath = create_mem_path('SIM', 'NAM', idm_context)
+    call mem_setptr(p, 'PRINT_INPUT', simnam_mempath)
+    paramlog = p
+    !
+    ! -- return
+    return
+  end function input_param_log
+
+  !> @brief load simulation summary info to input context
+  !<
+  subroutine simnam_load_dim()
+    use MemoryHelperModule, only: create_mem_path
+    use MemoryManagerModule, only: mem_allocate, mem_setptr
+    use SimVariablesModule, only: idm_context
+    use CharacterStringModule, only: CharacterStringType
+    character(len=LENMEMPATH) :: sim_mempath, simnam_mempath
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: mtypes !< model types
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: etypes !< model types
+    integer(I4B), pointer :: nummodels => null()
+    integer(I4B), pointer :: numexchanges => null()
+    !
+    ! -- set memory paths
+    sim_mempath = create_mem_path(component='SIM', context=idm_context)
+    simnam_mempath = create_mem_path('SIM', 'NAM', idm_context)
+    !
+    ! -- set pointers to loaded simnam arrays
+    call mem_setptr(mtypes, 'MTYPE', simnam_mempath)
+    call mem_setptr(etypes, 'EXGTYPE', simnam_mempath)
+    !
+    ! -- allocate variables
+    call mem_allocate(nummodels, 'NUMMODELS', sim_mempath)
+    call mem_allocate(numexchanges, 'NUMEXCHANGES', sim_mempath)
+    !
+    ! -- set values
+    nummodels = size(mtypes)
+    numexchanges = size(etypes)
+    !
+    ! -- return
+    return
+  end subroutine simnam_load_dim
+
+  !> @brief set sim nam input context default integer value
+  !<
+  subroutine allocate_simnam_int(input_mempath, idt)
+    use MemoryManagerModule, only: mem_allocate
+    use SimVariablesModule, only: isimcontinue, isimcheck, simfile
+    character(len=LENMEMPATH), intent(in) :: input_mempath
+    type(InputParamDefinitionType), pointer, intent(in) :: idt
+    integer(I4B), pointer :: intvar => null()
+    !
+    ! -- allocate and set default
+    call mem_allocate(intvar, idt%mf6varname, input_mempath)
+    !
+    select case (idt%mf6varname)
+    case ('CONTINUE')
+      intvar = isimcontinue
+    case ('NOCHECK')
+      intvar = isimcheck
+    case ('MAXERRORS')
+      intvar = 1000 !< MessageType max_message
+    case ('MXITER')
+      intvar = 1
+    case ('PRINT_INPUT')
+      intvar = 0
+    case default
+      write (errmsg, '(a,a)') &
+        'Programming error. Idm SIMNAM Load default value setting '&
+        &'is unhandled for this variable: ', &
+        trim(idt%mf6varname)
+      call store_error(errmsg)
+      call store_error_filename(simfile)
+    end select
+    !
+    ! -- return
+    return
+  end subroutine allocate_simnam_int
+
+  !> @brief MODFLOW 6 mfsim.nam parameter allocate and set
+  !<
+  subroutine allocate_simnam_param(input_mempath, idt)
+    use SimVariablesModule, only: simfile
+    use MemoryManagerModule, only: mem_allocate
+    use CharacterStringModule, only: CharacterStringType
+    character(len=LENMEMPATH), intent(in) :: input_mempath
+    type(InputParamDefinitionType), pointer, intent(in) :: idt
+    character(len=LINELENGTH), pointer :: cstr => null()
+    type(CharacterStringType), dimension(:), &
+      pointer, contiguous :: acharstr1d => null()
+    !
+    ! -- initialize
+    !
+    select case (idt%datatype)
+    case ('KEYWORD', 'INTEGER')
+      !
+      ! -- allocate and set default
+      call allocate_simnam_int(input_mempath, idt)
+      !
+    case ('STRING')
+      !
+      ! -- did this param originate from sim namfile RECARRAY type
+      if (idt%in_record) then
+        !
+        ! -- allocate 0 size CharacterStringType array
+        call mem_allocate(acharstr1d, LINELENGTH, 0, idt%mf6varname, &
+                          input_mempath)
+      else
+        !
+        ! -- allocate empty string
+        call mem_allocate(cstr, LINELENGTH, idt%mf6varname, input_mempath)
+        cstr = ''
+      end if
+    case default
+      write (errmsg, '(a,a)') &
+        'Programming error. IdmLoad unhandled datatype: ', &
+        trim(idt%datatype)
+      call store_error(errmsg)
+      call store_error_filename(simfile)
+    end select
+    !
+    ! -- return
+    return
+  end subroutine allocate_simnam_param
+
+  !> @brief MODFLOW 6 mfsim.nam input context parameter allocation
+  !<
+  subroutine simnam_allocate()
+    use MemoryHelperModule, only: create_mem_path
+    use MemoryManagerModule, only: get_isize, mem_allocate
+    use SimVariablesModule, only: idm_context
+    use CharacterStringModule, only: CharacterStringType
+    character(len=LENMEMPATH) :: input_mempath
+    type(ModflowInputType) :: mf6_input
+    type(InputParamDefinitionType), pointer :: idt
+    integer(I4B) :: iparam, isize
+    !
+    ! -- set memory path
+    input_mempath = create_mem_path('SIM', 'NAM', idm_context)
+    !
+    ! -- create description of input
+    mf6_input = getModflowInput('NAM6', 'SIM', 'NAM', 'SIM', 'NAM')
+    !
+    ! -- allocate sim namfile parameters if not in input context
+    do iparam = 1, size(mf6_input%param_dfns)
+      !
+      ! -- assign param definition pointer
+      idt => mf6_input%param_dfns(iparam)
+      !
+      ! -- check if variable is already allocated
+      call get_isize(idt%mf6varname, input_mempath, isize)
+      !
+      if (isize < 0) then
+        !
+        ! -- allocate and set parameter
+        call allocate_simnam_param(input_mempath, idt)
+        !
+      end if
+    end do
+    !
+    ! -- return
+    return
+  end subroutine simnam_allocate
+
+end module IdmLoadModule
diff --git a/src/Utilities/Idm/IdmLogger.f90 b/src/Utilities/Idm/IdmLogger.f90
index de88f8cba14..b5a52f6cdf5 100644
--- a/src/Utilities/Idm/IdmLogger.f90
+++ b/src/Utilities/Idm/IdmLogger.f90
@@ -14,6 +14,8 @@ module IdmLoggerModule
   private
   public :: idm_log_header
   public :: idm_log_close
+  public :: idm_log_period_header
+  public :: idm_log_period_close
   public :: idm_log_var
 
   interface idm_log_var
@@ -21,7 +23,8 @@ module IdmLoggerModule
       idm_log_var_int1d, idm_log_var_int2d, &
       idm_log_var_int3d, idm_log_var_dbl, &
       idm_log_var_dbl1d, idm_log_var_dbl2d, &
-      idm_log_var_dbl3d, idm_log_var_str
+      idm_log_var_dbl3d, idm_log_var_str, &
+      idm_log_var_ts
   end interface idm_log_var
 
 contains
@@ -47,10 +50,54 @@ subroutine idm_log_close(component, subcomponent, iout)
     integer(I4B), intent(in) :: iout
 
     if (iparamlog > 0 .and. iout > 0) then
-      write (iout, '(1x,a,/)') 'Loading input complete...'
+      write (iout, '(1x,a)') 'Loading input complete...'
     end if
   end subroutine idm_log_close
 
+  !> @ brief log a dynamic header message
+  !<
+  subroutine idm_log_period_header(component, iout)
+    use TdisModule, only: kper, kstp
+    character(len=*), intent(in) :: component !< component name
+    integer(I4B), intent(in) :: iout
+
+    if (iparamlog > 0 .and. iout > 0 .and. kstp == 1) then
+      write (iout, '(/1x,a,i0,a)') 'IDP PERIOD ', kper, &
+        ' load for component: '//trim(component)
+    end if
+  end subroutine idm_log_period_header
+
+  !> @ brief log the period closing message
+  !<
+  subroutine idm_log_period_close(iout)
+    use TdisModule, only: kstp
+    integer(I4B), intent(in) :: iout
+
+    if (iparamlog > 0 .and. iout > 0 .and. kstp == 1) then
+      !backspace iout
+      write (iout, '(1x,a,/)') 'IDP component dynamic load complete...'
+    end if
+  end subroutine idm_log_period_close
+
+  !> @ brief log the period closing message
+  !<
+  subroutine idm_log_var_ts(varname, mempath, iout, is_tas)
+    character(len=*), intent(in) :: varname !< variable name
+    character(len=*), intent(in) :: mempath !< variable memory path
+    integer(I4B), intent(in) :: iout
+    logical(LGP), intent(in) :: is_tas
+
+    if (iparamlog > 0 .and. iout > 0) then
+      if (is_tas) then
+        write (iout, '(3x, a, ": ", a)') &
+          'Time-array-series controlled dynamic variable detected', trim(varname)
+      else
+        write (iout, '(3x, a, ": ", a)') &
+          'Time-series controlled dynamic variable detected', trim(varname)
+      end if
+    end if
+  end subroutine idm_log_var_ts
+
   !> @brief Log type specific information logical
   !<
   subroutine idm_log_var_logical(p_mem, varname, mempath, iout)
diff --git a/src/Utilities/Idm/IdmSimulation.f90 b/src/Utilities/Idm/IdmSimulation.f90
deleted file mode 100644
index ecb8da877a7..00000000000
--- a/src/Utilities/Idm/IdmSimulation.f90
+++ /dev/null
@@ -1,246 +0,0 @@
-!> @brief This module contains the IdmSimulationModule
-!!
-!! This module contains the high-level routines for loading
-!! sim namefile parameters into the input context
-!!
-!<
-module IdmSimulationModule
-
-  use KindModule, only: DP, I4B, LGP
-  use ConstantsModule, only: LINELENGTH, LENMEMPATH
-  use SimModule, only: store_error
-  use SimVariablesModule, only: iout
-  use InputOutputModule, only: openfile, getunit
-  use InputDefinitionModule, only: InputParamDefinitionType
-  use ModflowInputModule, only: ModflowInputType, getModflowInput
-  use IdmMf6FileModule, only: input_load
-
-  implicit none
-  private
-  public :: simnam_load
-  public :: load_models
-
-contains
-
-  !> @brief load simulation summary info to input context
-  !<
-  subroutine simnam_load_dim()
-    use MemoryHelperModule, only: create_mem_path
-    use MemoryManagerModule, only: mem_allocate, mem_setptr
-    use SimVariablesModule, only: idm_context
-    use CharacterStringModule, only: CharacterStringType
-    character(len=LENMEMPATH) :: sim_mempath, simnam_mempath
-    type(CharacterStringType), dimension(:), contiguous, &
-      pointer :: mtypes !< model types
-    type(CharacterStringType), dimension(:), contiguous, &
-      pointer :: etypes !< model types
-    integer(I4B), pointer :: nummodels => null()
-    integer(I4B), pointer :: numexchanges => null()
-    !
-    ! -- set memory paths
-    sim_mempath = create_mem_path(component='SIM', context=idm_context)
-    simnam_mempath = create_mem_path('SIM', 'NAM', idm_context)
-    !
-    ! -- set pointers to loaded simnam arrays
-    call mem_setptr(mtypes, 'MTYPE', simnam_mempath)
-    call mem_setptr(etypes, 'EXGTYPE', simnam_mempath)
-    !
-    ! -- allocate variables
-    call mem_allocate(nummodels, 'NUMMODELS', sim_mempath)
-    call mem_allocate(numexchanges, 'NUMEXCHANGES', sim_mempath)
-    !
-    ! -- set values
-    nummodels = size(mtypes)
-    numexchanges = size(etypes)
-    !
-    ! -- return
-    return
-  end subroutine simnam_load_dim
-
-  !> @brief MODFLOW 6 mfsim.nam parameter set default value
-  !<
-  subroutine set_default_value(intvar, mf6varname)
-    use SimVariablesModule, only: isimcontinue, isimcheck
-    integer(I4B), pointer, intent(in) :: intvar
-    character(len=*), intent(in) :: mf6varname
-    character(len=LINELENGTH) :: errmsg
-    logical(LGP) :: terminate = .true.
-    !
-    ! -- load defaults for keyword/integer types
-    select case (mf6varname)
-      !
-    case ('CONTINUE')
-      intvar = isimcontinue
-      !
-    case ('NOCHECK')
-      intvar = isimcheck
-      !
-    case ('MAXERRORS')
-      intvar = 1000 !< MessageType max_message
-      !
-    case ('MXITER')
-      intvar = 1
-      !
-    case ('PRINT_INPUT')
-      intvar = 0
-      !
-    case default
-      write (errmsg, '(a,a)') &
-        'IdmSimulation set_default_value unhandled variable: ', &
-        trim(mf6varname)
-      call store_error(errmsg, terminate)
-    end select
-    !
-    ! -- return
-    return
-  end subroutine set_default_value
-
-  !> @brief MODFLOW 6 mfsim.nam input context parameter allocation
-  !<
-  subroutine simnam_allocate()
-    use MemoryHelperModule, only: create_mem_path
-    use MemoryManagerModule, only: get_isize, mem_allocate
-    use SimVariablesModule, only: idm_context
-    use CharacterStringModule, only: CharacterStringType
-    character(len=LENMEMPATH) :: input_mempath
-    type(ModflowInputType) :: mf6_input
-    type(InputParamDefinitionType), pointer :: idt
-    integer(I4B) :: iparam, isize
-    logical(LGP) :: terminate = .true.
-    integer(I4B), pointer :: intvar
-    character(len=LINELENGTH), pointer :: cstr
-    type(CharacterStringType), dimension(:), &
-      pointer, contiguous :: acharstr1d
-    character(len=LINELENGTH) :: errmsg
-    !
-    ! -- set memory path
-    input_mempath = create_mem_path('SIM', 'NAM', idm_context)
-    !
-    ! -- create description of input
-    mf6_input = getModflowInput('NAM6', 'SIM', 'NAM', 'SIM', 'NAM')
-    !
-    ! -- allocate sim namfile parameters if not in input context
-    do iparam = 1, size(mf6_input%param_dfns)
-      !
-      ! -- assign param definition pointer
-      idt => mf6_input%param_dfns(iparam)
-      !
-      ! -- check if variable is already allocated
-      call get_isize(idt%mf6varname, input_mempath, isize)
-      !
-      if (isize < 0) then
-        !
-        ! -- reset pointers
-        nullify (intvar)
-        nullify (acharstr1d)
-        nullify (cstr)
-        !
-        select case (idt%datatype)
-        case ('KEYWORD', 'INTEGER')
-          !
-          ! -- allocate and set default
-          call mem_allocate(intvar, idt%mf6varname, input_mempath)
-          call set_default_value(intvar, idt%mf6varname)
-        case ('STRING')
-          !
-          ! -- did this param originate from sim namfile RECARRAY type
-          if (idt%in_record) then
-            !
-            ! -- allocate 0 size CharacterStringType array
-            call mem_allocate(acharstr1d, LINELENGTH, 0, idt%mf6varname, &
-                              input_mempath)
-          else
-            !
-            ! -- allocate empty string
-            call mem_allocate(cstr, LINELENGTH, idt%mf6varname, input_mempath)
-            cstr = ''
-          end if
-        case default
-          write (errmsg, '(a,a)') &
-            'IdmSimulation unhandled datatype: ', &
-            trim(idt%datatype)
-          call store_error(errmsg, terminate)
-        end select
-      end if
-    end do
-    !
-    ! -- return
-    return
-  end subroutine simnam_allocate
-
-  !> @brief source indenpendent model load entry point
-  !<
-  subroutine load_models(model_loadmask, iout)
-    ! -- modules
-    use IdmMf6FileModule, only: load_models_mf6
-    ! -- dummy
-    integer(I4B), dimension(:), intent(in) :: model_loadmask
-    integer(I4B), intent(in) :: iout
-    ! -- locals
-    !
-    ! -- mf6 blockfile model load
-    call load_models_mf6(model_loadmask, iout)
-    !
-    ! -- return
-    return
-  end subroutine load_models
-
-  function input_param_log() result(paramlog)
-    use MemoryHelperModule, only: create_mem_path
-    use MemoryManagerModule, only: mem_setptr
-    use SimVariablesModule, only: idm_context
-    character(len=LENMEMPATH) :: simnam_mempath
-    integer(I4B) :: paramlog
-    integer(I4B), pointer :: p
-    !
-    ! -- read and set input value of PRINT_INPUT
-    simnam_mempath = create_mem_path('SIM', 'NAM', idm_context)
-    call mem_setptr(p, 'PRINT_INPUT', simnam_mempath)
-    !
-    paramlog = p
-    !
-    ! -- return
-    return
-  end function input_param_log
-
-  !> @brief MODFLOW 6 mfsim.nam input load routine
-  !<
-  subroutine simnam_load(paramlog)
-    use SimVariablesModule, only: simfile
-    use GenericUtilitiesModule, only: sim_message
-    integer(I4B), intent(inout) :: paramlog
-    integer(I4B) :: inunit
-    logical :: lexist
-    character(len=LINELENGTH) :: line
-    !
-    ! -- load mfsim.nam if it exists
-    inquire (file=trim(adjustl(simfile)), exist=lexist)
-    !
-    if (lexist) then
-      !
-      ! -- write name of namfile to stdout
-      write (line, '(2(1x,a))') 'Using Simulation name file:', &
-        trim(adjustl(simfile))
-      call sim_message(line, skipafter=1)
-      !
-      ! -- open namfile and load to input context
-      inunit = getunit()
-      call openfile(inunit, iout, trim(adjustl(simfile)), 'NAM')
-      call input_load('NAM6', 'SIM', 'NAM', 'SIM', 'NAM', inunit, iout)
-      close (inunit)
-    end if
-    !
-    ! -- allocate any unallocated simnam params
-    call simnam_allocate()
-    !
-    ! -- read and set input parameter logging keyword
-    paramlog = input_param_log()
-    !
-    ! -- memload summary info
-    call simnam_load_dim()
-    !
-    ! --return
-    return
-  end subroutine simnam_load
-
-end module IdmSimulationModule
diff --git a/src/Utilities/Idm/InputDefinition.f90 b/src/Utilities/Idm/InputDefinition.f90
index c4dfa5f09bf..0d488e50d90 100644
--- a/src/Utilities/Idm/InputDefinition.f90
+++ b/src/Utilities/Idm/InputDefinition.f90
@@ -7,6 +7,7 @@
 module InputDefinitionModule
 
   use KindModule, only: LGP
+  use ConstantsModule, only: LENVARNAME
 
   implicit none
   private
@@ -24,13 +25,14 @@ module InputDefinitionModule
     character(len=100) :: subcomponent_type = ''
     character(len=100) :: blockname = ''
     character(len=100) :: tagname = ''
-    character(len=100) :: mf6varname = ''
-    character(len=100) :: datatype = ''
+    character(len=LENVARNAME) :: mf6varname = ''
+    character(len=120) :: datatype = ''
     character(len=100) :: shape = ''
     logical(LGP) :: required = .false.
     logical(LGP) :: in_record = .false.
     logical(LGP) :: preserve_case = .false.
     logical(LGP) :: layered = .false.
+    logical(LGP) :: timeseries = .false.
   end type InputParamDefinitionType
 
   !> @brief derived type for storing block information
diff --git a/src/Utilities/Idm/InputLoadType.f90 b/src/Utilities/Idm/InputLoadType.f90
new file mode 100644
index 00000000000..24001ba17d6
--- /dev/null
+++ b/src/Utilities/Idm/InputLoadType.f90
@@ -0,0 +1,417 @@
+!> @brief This module contains the InputLoadTypeModule
+!!
+!! This module defines types that support generic IDP
+!! static and dynamic input loading.
+!!
+!<
+module InputLoadTypeModule
+
+  use KindModule, only: DP, I4B, LGP
+  use ConstantsModule, only: LINELENGTH, LENCOMPONENTNAME, LENMODELNAME
+  use ModflowInputModule, only: ModflowInputType
+  use ListModule, only: ListType
+  use InputDefinitionModule, only: InputParamDefinitionType
+
+  implicit none
+  private
+  public :: StaticPkgLoadBaseType
+  public :: DynamicPkgLoadBaseType
+  public :: ModelDynamicPkgsType
+  public :: AddDynamicModelToList, GetDynamicModelFromList
+  public :: StaticPkgLoadType, DynamicPkgLoadType
+
+  !> @brief derived type for source static load
+  !!
+  !! This derived type is a base concrete type for a model
+  !! package static load
+  !!
+  !<
+  type StaticPkgLoadType
+    type(ModflowInputType) :: mf6_input !< description of modflow6 input
+    character(len=LENCOMPONENTNAME) :: component_name !< name of component
+    character(len=LINELENGTH) :: component_input_name !< name of component input name, e.g. filename
+    character(len=LINELENGTH) :: input_name !< source name, e.g. name of input file
+    integer(I4B) :: iperblock
+  contains
+    procedure :: init => static_init
+    procedure :: destroy => static_destroy
+  end type StaticPkgLoadType
+
+  !> @brief base abstract type for source static load
+  !!
+  !! IDM sources should extend and implement this type
+  !!
+  !<
+  type, abstract, extends(StaticPkgLoadType) :: StaticPkgLoadBaseType
+  contains
+    procedure(load_if), deferred :: load
+  end type StaticPkgLoadBaseType
+
+  !> @brief derived type for source dynamic load
+  !!
+  !! This derived type is a base concrete type for a model
+  !! package dynamic (period) load
+  !!
+  !<
+  type :: DynamicPkgLoadType
+    type(ModflowInputType) :: mf6_input !< description of modflow6 input
+    character(len=LENMODELNAME) :: modelname !< name of model
+    character(len=LINELENGTH) :: modelfname !< name of model input file
+    character(len=LINELENGTH) :: sourcename !< source name, e.g. name of file
+    logical(LGP) :: readasarrays
+    integer(I4B) :: iperblock
+    integer(I4B) :: iout
+  contains
+    procedure :: init => dynamic_init
+    procedure :: df => dynamic_df
+    procedure :: ad => dynamic_ad
+    procedure :: destroy => dynamic_destroy
+  end type DynamicPkgLoadType
+
+  !> @brief base abstract type for source dynamic load
+  !!
+  !! IDM sources should extend and implement this type
+  !!
+  !<
+  type, abstract, extends(DynamicPkgLoadType) :: DynamicPkgLoadBaseType
+  contains
+    procedure(period_load_if), deferred :: rp
+  end type DynamicPkgLoadBaseType
+
+  !> @brief load interfaces for source static and dynamic types
+  !<
+  abstract interface
+    function load_if(this, iout) result(dynamic_loader)
+      import StaticPkgLoadBaseType, DynamicPkgLoadBaseType, I4B
+      class(StaticPkgLoadBaseType), intent(inout) :: this
+      integer(I4B), intent(in) :: iout
+      class(DynamicPkgLoadBaseType), pointer :: dynamic_loader
+    end function load_if
+    subroutine period_load_if(this)
+      import DynamicPkgLoadBaseType, I4B
+      class(DynamicPkgLoadBaseType), intent(inout) :: this
+    end subroutine
+  end interface
+
+  !> @brief derived type for storing a dynamic package load list
+  !!
+  !! This derived type is used to store a list of package
+  !! dynamic load types for a model
+  !!
+  !<
+  type :: ModelDynamicPkgsType
+    character(len=LENMODELNAME) :: modelname !< name of model
+    character(len=LINELENGTH) :: modelfname !< name of model input file
+    type(ListType) :: pkglist !< list of pointers to model dynamic package loaders
+    integer(I4B) :: iout
+  contains
+    procedure :: init => dynamicpkgs_init
+    procedure :: add => dynamicpkgs_add
+    procedure :: get => dynamicpkgs_get
+    procedure :: rp => dynamicpkgs_rp
+    procedure :: df => dynamicpkgs_df
+    procedure :: ad => dynamicpkgs_ad
+    procedure :: size => dynamicpkgs_size
+    procedure :: destroy => dynamicpkgs_destroy
+  end type ModelDynamicPkgsType
+
+contains
+
+  !> @brief initialize static package loader
+  !!
+  !<
+  subroutine static_init(this, mf6_input, component_name, component_input_name, &
+                         input_name)
+    class(StaticPkgLoadType), intent(inout) :: this
+    type(ModflowInputType), intent(in) :: mf6_input
+    character(len=*), intent(in) :: component_name
+    character(len=*), intent(in) :: component_input_name
+    character(len=*), intent(in) :: input_name
+    integer(I4B) :: iblock
+    !
+    this%mf6_input = mf6_input
+    this%component_name = component_name
+    this%component_input_name = component_input_name
+    this%input_name = input_name
+    this%iperblock = 0
+    !
+    ! -- identify period block definition
+    do iblock = 1, size(mf6_input%block_dfns)
+      !
+      if (mf6_input%block_dfns(iblock)%blockname == 'PERIOD') then
+        this%iperblock = iblock
+        exit
+      end if
+    end do
+    !
+    return
+  end subroutine static_init
+
+  subroutine static_destroy(this)
+    class(StaticPkgLoadType), intent(inout) :: this
+    !
+    return
+  end subroutine static_destroy
+
+  !> @brief initialize dynamic package loader
+  !!
+  !! Any managed memory pointed to from model/package context
+  !! must be allocated when derived dynamic loader is initialized.
+  !!
+  !<
+  subroutine dynamic_init(this, mf6_input, modelname, modelfname, source, &
+                          iperblock, iout)
+    use SimVariablesModule, only: errmsg
+    use SimModule, only: store_error, store_error_filename
+    class(DynamicPkgLoadType), intent(inout) :: this
+    type(ModflowInputType), intent(in) :: mf6_input
+    character(len=*), intent(in) :: modelname
+    character(len=*), intent(in) :: modelfname
+    character(len=*), intent(in) :: source
+    integer(I4B), intent(in) :: iperblock
+    integer(I4B), intent(in) :: iout
+    !
+    this%mf6_input = mf6_input
+    this%modelname = modelname
+    this%modelfname = modelfname
+    this%sourcename = source
+    this%iperblock = iperblock
+    this%iout = iout
+    !
+    ! -- throw error and exit if not found
+    if (this%iperblock == 0) then
+      write (errmsg, '(a,a)') &
+        'Programming error. (IDM) PERIOD block not found in '&
+        &'dynamic package input block dfns: ', &
+        trim(mf6_input%subcomponent_name)
+      call store_error(errmsg)
+      call store_error_filename(this%sourcename)
+    else
+      !
+      this%readasarrays = (.not. mf6_input%block_dfns(iperblock)%aggregate)
+    end if
+    !
+    ! -- return
+    return
+  end subroutine dynamic_init
+
+  !> @brief dynamic package loader define
+  !!
+  !<
+  subroutine dynamic_df(this)
+    class(DynamicPkgLoadType), intent(inout) :: this
+    !
+    ! override in derived type
+    !
+    return
+  end subroutine dynamic_df
+
+  !> @brief dynamic package loader advance
+  !!
+  !<
+  subroutine dynamic_ad(this)
+    class(DynamicPkgLoadType), intent(inout) :: this
+    !
+    ! override in derived type
+    !
+    return
+  end subroutine dynamic_ad
+
+  !> @brief dynamic package loader destroy
+  !!
+  !<
+  subroutine dynamic_destroy(this)
+    use MemoryManagerExtModule, only: memorylist_remove
+    use SimVariablesModule, only: idm_context
+    class(DynamicPkgLoadType), intent(inout) :: this
+    !
+    ! -- deallocate package static and dynamic input context
+    call memorylist_remove(this%mf6_input%component_name, &
+                           this%mf6_input%subcomponent_name, &
+                           idm_context)
+    !
+    return
+  end subroutine dynamic_destroy
+
+  !> @brief model dynamic packages init
+  !!
+  !<
+  subroutine dynamicpkgs_init(this, modelname, modelfname, iout)
+    class(ModelDynamicPkgsType), intent(inout) :: this
+    character(len=*), intent(in) :: modelname
+    character(len=*), intent(in) :: modelfname
+    integer(I4B), intent(in) :: iout
+    !
+    this%modelname = modelname
+    this%modelfname = modelfname
+    this%iout = iout
+    !
+    return
+  end subroutine dynamicpkgs_init
+
+  !> @brief add package to model dynamic packages list
+  !!
+  !<
+  subroutine dynamicpkgs_add(this, dynamic_pkg)
+    class(ModelDynamicPkgsType), intent(inout) :: this
+    class(DynamicPkgLoadBaseType), pointer, intent(inout) :: dynamic_pkg
+    class(*), pointer :: obj
+    !
+    obj => dynamic_pkg
+    call this%pkglist%add(obj)
+    !
+    return
+  end subroutine dynamicpkgs_add
+
+  !> @brief retrieve package from model dynamic packages list
+  !!
+  !<
+  function dynamicpkgs_get(this, idx) result(res)
+    class(ModelDynamicPkgsType), intent(inout) :: this
+    integer(I4B), intent(in) :: idx
+    class(DynamicPkgLoadBaseType), pointer :: res
+    class(*), pointer :: obj
+    !
+    nullify (res)
+    obj => this%pkglist%GetItem(idx)
+    !
+    if (associated(obj)) then
+      select type (obj)
+      class is (DynamicPkgLoadBaseType)
+        res => obj
+      end select
+    end if
+    !
+    return
+  end function dynamicpkgs_get
+
+  !> @brief read and prepare model dynamic packages
+  !!
+  !<
+  subroutine dynamicpkgs_rp(this)
+    use IdmLoggerModule, only: idm_log_period_header, idm_log_period_close
+    class(ModelDynamicPkgsType), intent(inout) :: this
+    class(DynamicPkgLoadBaseType), pointer :: dynamic_pkg
+    integer(I4B) :: n
+    !
+    call idm_log_period_header(this%modelname, this%iout)
+    !
+    do n = 1, this%pkglist%Count()
+      dynamic_pkg => this%get(n)
+      call dynamic_pkg%rp()
+    end do
+    !
+    call idm_log_period_close(this%iout)
+    !
+    return
+  end subroutine dynamicpkgs_rp
+
+  !> @brief define model dynamic packages
+  !!
+  !<
+  subroutine dynamicpkgs_df(this)
+    class(ModelDynamicPkgsType), intent(inout) :: this
+    class(DynamicPkgLoadBaseType), pointer :: dynamic_pkg
+    integer(I4B) :: n
+    !
+    do n = 1, this%pkglist%Count()
+      dynamic_pkg => this%get(n)
+      call dynamic_pkg%df()
+    end do
+    !
+    return
+  end subroutine dynamicpkgs_df
+
+  !> @brief advance model dynamic packages
+  !!
+  !<
+  subroutine dynamicpkgs_ad(this)
+    class(ModelDynamicPkgsType), intent(inout) :: this
+    class(DynamicPkgLoadBaseType), pointer :: dynamic_pkg
+    integer(I4B) :: n
+    !
+    do n = 1, this%pkglist%Count()
+      dynamic_pkg => this%get(n)
+      call dynamic_pkg%ad()
+    end do
+    !
+    return
+  end subroutine dynamicpkgs_ad
+
+  !> @brief get size of model dynamic packages list
+  !!
+  !<
+  function dynamicpkgs_size(this) result(size)
+    class(ModelDynamicPkgsType), intent(inout) :: this
+    integer(I4B) :: size
+    !
+    size = this%pkglist%Count()
+    !
+    return
+  end function dynamicpkgs_size
+
+  !> @brief destroy model dynamic packages object
+  !!
+  !<
+  subroutine dynamicpkgs_destroy(this)
+    class(ModelDynamicPkgsType), intent(inout) :: this
+    class(DynamicPkgLoadBaseType), pointer :: dynamic_pkg
+    integer(I4B) :: n
+    !
+    do n = 1, this%pkglist%Count()
+      dynamic_pkg => this%get(n)
+      call dynamic_pkg%destroy()
+      deallocate (dynamic_pkg)
+      nullify (dynamic_pkg)
+    end do
+    !
+    call this%pkglist%Clear()
+    !
+    return
+  end subroutine dynamicpkgs_destroy
+
+  !> @brief add model dynamic packages object to list
+  !!
+  !<
+  subroutine AddDynamicModelToList(list, model_dynamic)
+    ! -- dummy variables
+    type(ListType), intent(inout) :: list !< package list
+    class(ModelDynamicPkgsType), pointer, intent(inout) :: model_dynamic
+    ! -- local variables
+    class(*), pointer :: obj
+    !
+    obj => model_dynamic
+    call list%Add(obj)
+    !
+    ! -- return
+    return
+  end subroutine AddDynamicModelToList
+
+  !> @brief get model dynamic packages object from list
+  !!
+  !<
+  function GetDynamicModelFromList(list, idx) result(res)
+    ! -- dummy variables
+    type(ListType), intent(inout) :: list !< spd list
+    integer(I4B), intent(in) :: idx !< package number
+    class(ModelDynamicPkgsType), pointer :: res
+    ! -- local variables
+    class(*), pointer :: obj
+    !
+    ! -- initialize res
+    res => null()
+    !
+    ! -- get the object from the list
+    obj => list%GetItem(idx)
+    if (associated(obj)) then
+      select type (obj)
+      class is (ModelDynamicPkgsType)
+        res => obj
+      end select
+    end if
+    !
+    ! -- return
+    return
+  end function GetDynamicModelFromList
+
+end module InputLoadTypeModule
diff --git a/src/Utilities/Idm/ModelPackageInputs.f90 b/src/Utilities/Idm/ModelPackageInputs.f90
index 25ea01001a6..9e57f8910d0 100644
--- a/src/Utilities/Idm/ModelPackageInputs.f90
+++ b/src/Utilities/Idm/ModelPackageInputs.f90
@@ -7,8 +7,9 @@
 module ModelPackageInputsModule
 
   use KindModule, only: DP, I4B, LGP
+  use SimVariablesModule, only: errmsg
   use ConstantsModule, only: LINELENGTH, LENMEMPATH, LENMODELNAME, LENFTYPE, &
-                             LENPACKAGETYPE, LENPACKAGENAME
+                             LENPACKAGETYPE, LENPACKAGENAME, LENCOMPONENTNAME
   use SimModule, only: store_error, store_error_filename
   use SimVariablesModule, only: iout
   use ArrayHandlersModule, only: expandarray
@@ -16,46 +17,8 @@ module ModelPackageInputsModule
 
   implicit none
   private
-  public :: NIUNIT_GWF, NIUNIT_GWT
   public :: ModelPackageInputsType
 
-  ! -- GWF base package types, ordered for memload
-  integer(I4B), parameter :: GWF_NBASEPKG = 50
-  character(len=LENPACKAGETYPE), dimension(GWF_NBASEPKG) :: GWF_BASEPKG
-  data GWF_BASEPKG/'DIS6 ', 'DISV6', 'DISU6', '     ', '     ', & !  5
-                  &'NPF6 ', 'BUY6 ', 'VSC6 ', 'GNC6 ', '     ', & ! 10
-                  &'HFB6 ', 'STO6 ', 'IC6  ', '     ', '     ', & ! 15
-                  &'MVR6 ', 'OC6  ', 'OBS6 ', '     ', '     ', & ! 20
-                  &30*'     '/ ! 50
-
-  ! -- GWF multi package types, ordered for memload
-  integer(I4B), parameter :: GWF_NMULTIPKG = 50
-  character(len=LENPACKAGETYPE), dimension(GWF_NMULTIPKG) :: GWF_MULTIPKG
-  data GWF_MULTIPKG/'WEL6 ', 'DRN6 ', 'RIV6 ', 'GHB6 ', '     ', & !  5
-                   &'RCH6 ', 'EVT6 ', 'CHD6 ', 'CSUB6', '     ', & ! 10
-                   &'MAW6 ', 'SFR6 ', 'LAK6 ', 'UZF6 ', 'API6 ', & ! 15
-                   &35*'     '/ ! 50
-
-  ! -- GWT base package types, ordered for memload
-  integer(I4B), parameter :: GWT_NBASEPKG = 50
-  character(len=LENPACKAGETYPE), dimension(GWT_NBASEPKG) :: GWT_BASEPKG
-  data GWT_BASEPKG/'DIS6 ', 'DISV6', 'DISU6', '     ', '     ', & !  5
-                  &'IC6  ', 'FMI6 ', 'MST6 ', 'ADV6 ', '     ', & ! 10
-                  &'DSP6 ', 'SSM6 ', 'MVT6 ', 'OC6  ', '     ', & ! 15
-                  &'OBS6 ', '     ', '     ', '     ', '     ', & ! 20
-                  &30*'     '/ ! 50
-
-  ! -- GWT multi package types, ordered for memload
-  integer(I4B), parameter :: GWT_NMULTIPKG = 50
-  character(len=LENPACKAGETYPE), dimension(GWT_NMULTIPKG) :: GWT_MULTIPKG
-  data GWT_MULTIPKG/'CNC6 ', 'SRC6 ', 'LKT6 ', 'IST6 ', '     ', & !  5
-                   &'SFT6 ', 'MWT6 ', 'UZT6 ', 'API6 ', '     ', & ! 10
-                   &40*'     '/ ! 50
-
-  ! -- size of supported model package arrays
-  integer(I4B), parameter :: NIUNIT_GWF = GWF_NBASEPKG + GWF_NMULTIPKG
-  integer(I4B), parameter :: NIUNIT_GWT = GWT_NBASEPKG + GWT_NMULTIPKG
-
   !> @brief derived type for loadable package type
   !!
   !!  This derived type is used to store package instance
@@ -63,10 +26,10 @@ module ModelPackageInputsModule
   !!
   !<
   type :: LoadablePackageType
-    ! -- package type, e.g. 'DIS6 or CHD6'
+    ! -- package type, e.g. 'DIS6' or 'CHD6'
     character(len=LENPACKAGETYPE) :: pkgtype
-    ! -- component type, e.g. 'DIS or CHD'
-    character(len=LENFTYPE) :: component_type
+    ! -- component type, e.g. 'DIS' or 'CHD'
+    character(len=LENCOMPONENTNAME) :: subcomponent_type
     ! -- package instance attribute arrays
     character(len=LINELENGTH), dimension(:), allocatable :: filenames
     character(len=LENPACKAGENAME), dimension(:), allocatable :: pkgnames
@@ -92,8 +55,9 @@ module ModelPackageInputsModule
     character(len=LINELENGTH) :: modelfname
     character(len=LENMODELNAME) :: modelname
     ! -- component type
-    character(len=LENFTYPE) :: component_type ! -- e.g. 'GWF'
-    ! -- model mempath
+    character(len=LENCOMPONENTNAME) :: component_type ! -- e.g. 'GWF'
+    ! -- mempaths
+    character(len=LENMEMPATH) :: input_mempath
     character(len=LENMEMPATH) :: model_mempath
     ! -- pointers to created managed memory
     type(CharacterStringType), dimension(:), contiguous, &
@@ -123,101 +87,29 @@ module ModelPackageInputsModule
 
 contains
 
-  !> @brief set supported package types for model
-  !<
-  subroutine supported_model_packages(mtype, pkgtypes, numpkgs)
-    ! -- modules
-    ! -- dummy
-    character(len=LENFTYPE), intent(in) :: mtype
-    character(len=LENPACKAGETYPE), dimension(:), allocatable, &
-      intent(inout) :: pkgtypes
-    integer(I4B), intent(inout) :: numpkgs
-    ! -- local
-    !
-    select case (mtype)
-    case ('GWF6')
-      numpkgs = GWF_NBASEPKG + GWF_NMULTIPKG
-      allocate (pkgtypes(numpkgs))
-      pkgtypes = [GWF_BASEPKG, GWF_MULTIPKG]
-      !
-    case ('GWT6')
-      numpkgs = GWT_NBASEPKG + GWT_NMULTIPKG
-      allocate (pkgtypes(numpkgs))
-      pkgtypes = [GWT_BASEPKG, GWT_MULTIPKG]
-      !
-    case default
-    end select
-    !
-    ! -- return
-    return
-  end subroutine supported_model_packages
-
-  !> @brief component from package or model type
-  !<
-  function component_type(pkgtype) !result(componenttype)
-    ! -- modules
-    ! -- dummy
-    character(len=LENPACKAGETYPE), intent(in) :: pkgtype
-    ! -- return
-    character(len=LENFTYPE) :: component_type
-    ! -- local
-    integer(I4B) :: i, ilen
-    !
-    component_type = ''
-    !
-    ilen = len_trim(pkgtype)
-    do i = 1, ilen
-      if (pkgtype(i:i) == '6') then
-        write (component_type, '(a)') trim(pkgtype(1:i - 1))
-      end if
-    end do
-    !
-    ! -- return
-    return
-  end function component_type
-
   !> @brief does model support multiple instances of this package type
   !<
   function multi_pkg_type(mtype_component, ptype_component, pkgtype) &
     result(multi_pkg)
     ! -- modules
     use IdmDfnSelectorModule, only: idm_integrated, idm_multi_package
+    use ModelPackageInputModule, only: multi_package_type
     ! -- dummy
-    character(len=LENFTYPE), intent(in) :: mtype_component
-    character(len=LENFTYPE), intent(in) :: ptype_component
+    character(len=LENCOMPONENTNAME), intent(in) :: mtype_component
+    character(len=LENCOMPONENTNAME), intent(in) :: ptype_component
     character(len=LENFTYPE), intent(in) :: pkgtype
     ! -- return
     logical(LGP) :: multi_pkg
     ! -- local
-    integer(I4B) :: n
     !
     multi_pkg = .false.
     !
     if (idm_integrated(mtype_component, ptype_component)) then
-      !
       multi_pkg = idm_multi_package(mtype_component, ptype_component)
       !
     else
+      multi_pkg = multi_package_type(mtype_component, ptype_component, pkgtype)
       !
-      select case (mtype_component)
-      case ('GWF')
-        do n = 1, GWF_NMULTIPKG
-          if (GWF_MULTIPKG(n) == pkgtype) then
-            multi_pkg = .true.
-            exit
-          end if
-        end do
-        !
-      case ('GWT')
-        do n = 1, GWT_NMULTIPKG
-          if (GWT_MULTIPKG(n) == pkgtype) then
-            multi_pkg = .true.
-            exit
-          end if
-        end do
-        !
-      case default
-      end select
     end if
     !
     ! -- return
@@ -226,17 +118,19 @@ end function multi_pkg_type
 
   !> @brief create a new package type
   !<
-  subroutine pkgtype_create(this, modelname, pkgtype)
+  subroutine pkgtype_create(this, modeltype, modelname, pkgtype)
     ! -- modules
+    use SourceCommonModule, only: idm_subcomponent_type
     ! -- dummy
     class(LoadablePackageType) :: this
+    character(len=*), intent(in) :: modeltype
     character(len=*), intent(in) :: modelname
     character(len=*), intent(in) :: pkgtype
     ! -- local
     !
     ! -- initialize
     this%pkgtype = pkgtype
-    this%component_type = component_type(pkgtype)
+    this%subcomponent_type = idm_subcomponent_type(modeltype, pkgtype)
     this%pnum = 0
     !
     ! -- allocate arrays
@@ -256,8 +150,10 @@ subroutine pkgtype_add(this, modelname, mtype_component, filetype, &
     ! -- modules
     use MemoryManagerModule, only: mem_allocate
     use MemoryHelperModule, only: create_mem_path
+    use MemoryManagerExtModule, only: mem_set_value
     use SimVariablesModule, only: idm_context
     use IdmDfnSelectorModule, only: idm_integrated, idm_multi_package
+    use SourceCommonModule, only: idm_subcomponent_name
     ! -- dummy
     class(LoadablePackageType) :: this
     character(len=*), intent(in) :: modelname
@@ -267,7 +163,7 @@ subroutine pkgtype_add(this, modelname, mtype_component, filetype, &
     character(len=*), intent(in) :: pkgname
     integer(I4B), intent(in) :: iout
     ! -- local
-    character(len=LENPACKAGENAME) :: sc_name
+    character(len=LENPACKAGENAME) :: sc_name, pname
     character(len=LENMEMPATH) :: mempath
     character(len=LINELENGTH), pointer :: cstr
     !
@@ -283,17 +179,18 @@ subroutine pkgtype_add(this, modelname, mtype_component, filetype, &
     this%pkgnames(this%pnum) = pkgname
     this%inunits(this%pnum) = 0
     !
+    ! -- set pkgname if empty
+    if (this%pkgnames(this%pnum) == '') then
+      write (pname, '(a,i0)') trim(this%subcomponent_type)//'-', this%pnum
+      this%pkgnames(this%pnum) = pname
+    end if
+    !
     ! -- set up input context for model
-    if (idm_integrated(mtype_component, this%component_type)) then
+    if (idm_integrated(mtype_component, this%subcomponent_type)) then
       !
       ! -- set subcomponent name
-      if (idm_multi_package(mtype_component, this%component_type)) then
-        !
-        sc_name = pkgname
-      else
-        !
-        sc_name = this%component_type
-      end if
+      sc_name = idm_subcomponent_name(mtype_component, this%subcomponent_type, &
+                                      this%pkgnames(this%pnum))
       !
       ! -- create and store the mempath
       this%mempaths(this%pnum) = &
@@ -303,6 +200,7 @@ subroutine pkgtype_add(this, modelname, mtype_component, filetype, &
       mempath = create_mem_path(modelname, sc_name, idm_context)
       call mem_allocate(cstr, LINELENGTH, 'INPUT_FNAME', mempath)
       cstr = filename
+      !
     else
       !
       ! -- set mempath empty
@@ -338,6 +236,8 @@ subroutine modelpkgs_init(this, modeltype, modelfname, modelname, iout)
     use MemoryHelperModule, only: create_mem_path
     use MemoryManagerModule, only: mem_allocate
     use SimVariablesModule, only: idm_context
+    use SourceCommonModule, only: idm_component_type
+    use ModelPackageInputModule, only: supported_model_packages
     ! -- dummy
     class(ModelPackageInputsType) :: this
     character(len=*), intent(in) :: modeltype
@@ -350,13 +250,14 @@ subroutine modelpkgs_init(this, modeltype, modelfname, modelname, iout)
     this%modeltype = modeltype
     this%modelfname = modelfname
     this%modelname = modelname
-    this%component_type = component_type(modeltype)
+    this%component_type = idm_component_type(modeltype)
     this%iout = iout
     !
     ! -- allocate and set model supported package types
     call supported_model_packages(modeltype, this%cunit, this%niunit)
     !
-    ! -- set model memory path
+    ! -- set memory paths
+    this%input_mempath = create_mem_path(this%modelname, 'NAM', idm_context)
     this%model_mempath = create_mem_path(component=this%modelname, &
                                          context=idm_context)
     !
@@ -390,7 +291,6 @@ subroutine modelpkgs_create(this, ftypes)
     character(len=LENPACKAGETYPE) :: ftype
     integer(I4B) :: n, m
     logical(LGP) :: found
-    character(len=LINELENGTH) :: errmsg
     !
     ! -- allocate
     allocate (cunit_idxs(0))
@@ -398,7 +298,7 @@ subroutine modelpkgs_create(this, ftypes)
     ! -- identify input packages and check that each is supported
     do n = 1, size(ftypes)
       !
-      ! -- type from model name file packages block
+      ! -- type from model nam file packages block
       ftype = ftypes(n)
       found = .false.
       !
@@ -440,7 +340,8 @@ subroutine modelpkgs_create(this, ftypes)
     !
     ! -- create sorted LoadablePackageType object list
     do n = 1, size(cunit_idxs)
-      call this%pkglist(n)%create(this%modelname, this%cunit(cunit_idxs(n)))
+      call this%pkglist(n)%create(this%modeltype, this%modelname, &
+                                  this%cunit(cunit_idxs(n)))
     end do
     !
     ! -- cleanup
@@ -482,9 +383,7 @@ end subroutine modelpkgs_add
   !<
   subroutine modelpkgs_addpkgs(this)
     ! -- modules
-    use MemoryHelperModule, only: create_mem_path
     use MemoryManagerModule, only: mem_setptr
-    use SimVariablesModule, only: idm_context
     ! -- dummy
     class(ModelPackageInputsType) :: this
     ! -- local
@@ -494,17 +393,13 @@ subroutine modelpkgs_addpkgs(this)
       pointer :: fnames !< file names
     type(CharacterStringType), dimension(:), contiguous, &
       pointer :: pnames !< package names
-    character(len=LENMEMPATH) :: input_mempath
     character(len=LINELENGTH) :: ftype, fname, pname
     integer(I4B) :: n
     !
-    ! -- set input memory path
-    input_mempath = create_mem_path(this%modelname, 'NAM', idm_context)
-    !
     ! -- set pointers to input context model package attribute arrays
-    call mem_setptr(ftypes, 'FTYPE', input_mempath)
-    call mem_setptr(fnames, 'FNAME', input_mempath)
-    call mem_setptr(pnames, 'PNAME', input_mempath)
+    call mem_setptr(ftypes, 'FTYPE', this%input_mempath)
+    call mem_setptr(fnames, 'FNAME', this%input_mempath)
+    call mem_setptr(pnames, 'PNAME', this%input_mempath)
     !
     ! -- create the package list
     call this%create(ftypes)
@@ -517,9 +412,6 @@ subroutine modelpkgs_addpkgs(this)
       fname = fnames(n)
       pname = pnames(n)
       !
-      ! TODO: name pkg here if not provided, this is expected to cause
-      !       failures for multi-pkg types when names aren't provided
-      !
       ! -- add this instance to package list
       call this%add(ftype, fname, pname)
     end do
@@ -539,7 +431,6 @@ function modelpkgs_pkgcount(this) result(pnum)
     integer(I4B) :: pnum
     ! -- local
     integer(I4B) :: n
-    character(len=LINELENGTH) :: errmsg
     !
     ! -- initialize
     pnum = 0
@@ -548,7 +439,7 @@ function modelpkgs_pkgcount(this) result(pnum)
     do n = 1, size(this%pkglist)
       !
       if (multi_pkg_type(this%component_type, &
-                         this%pkglist(n)%component_type, &
+                         this%pkglist(n)%subcomponent_type, &
                          this%pkglist(n)%pkgtype)) then
         ! multiple instances ok
       else
diff --git a/src/Utilities/Idm/ModflowInput.f90 b/src/Utilities/Idm/ModflowInput.f90
index d8c316ecfc0..74e63c35da8 100644
--- a/src/Utilities/Idm/ModflowInput.f90
+++ b/src/Utilities/Idm/ModflowInput.f90
@@ -32,12 +32,13 @@ module ModflowInputModule
   !!
   !<
   type ModflowInputType
-    character(len=LENPACKAGETYPE) :: pkgtype
+    character(len=LENCOMPONENTNAME) :: pkgtype
     character(len=LENCOMPONENTNAME) :: component_type
     character(len=LENCOMPONENTNAME) :: subcomponent_type
     character(len=LENCOMPONENTNAME) :: component_name
     character(len=LENCOMPONENTNAME) :: subcomponent_name
     character(len=LENMEMPATH) :: mempath
+    character(len=LENMEMPATH) :: component_mempath
     type(InputBlockDefinitionType), dimension(:), pointer :: block_dfns
     type(InputParamDefinitionType), dimension(:), pointer :: aggregate_dfns
     type(InputParamDefinitionType), dimension(:), pointer :: param_dfns
@@ -47,29 +48,120 @@ module ModflowInputModule
 
   !> @brief function to return ModflowInputType
   !<
-  function getModflowInput(pkgtype, component_type, &
-                           subcomponent_type, component_name, subcomponent_name) &
+  function getModflowInput(pkgtype, component_type, subcomponent_type, &
+                           component_name, subcomponent_name, filename) &
     result(mf6_input)
     character(len=*), intent(in) :: pkgtype !< package type to load, such as DIS6, DISV6, NPF6
     character(len=*), intent(in) :: component_type !< component type, such as GWF or GWT
     character(len=*), intent(in) :: subcomponent_type !< subcomponent type, such as DIS or NPF
     character(len=*), intent(in) :: component_name !< component name, such as MYGWFMODEL
     character(len=*), intent(in) :: subcomponent_name !< subcomponent name, such as MYWELLPACKAGE
+    character(len=*), optional, intent(in) :: filename !< optional name of package input file
     type(ModflowInputType) :: mf6_input
+    character(len=LENPACKAGETYPE) :: dfn_subcomponent_type
 
+    ! -- set subcomponent type
+    if (present(filename)) then
+      dfn_subcomponent_type = update_sc_type(pkgtype, filename, component_type, &
+                                             subcomponent_type)
+    else
+      dfn_subcomponent_type = trim(subcomponent_type)
+    end if
+
+    ! -- set input attributes
     mf6_input%pkgtype = trim(pkgtype)
     mf6_input%component_type = trim(component_type)
-    mf6_input%subcomponent_type = trim(subcomponent_type)
+    mf6_input%subcomponent_type = trim(dfn_subcomponent_type)
     mf6_input%component_name = trim(component_name)
     mf6_input%subcomponent_name = trim(subcomponent_name)
 
+    ! -- set mempaths
     mf6_input%mempath = create_mem_path(component_name, subcomponent_name, &
                                         idm_context)
+    mf6_input%component_mempath = create_mem_path(component=component_name, &
+                                                  context=idm_context)
 
-    mf6_input%block_dfns => block_definitions(component_type, subcomponent_type)
-    mf6_input%aggregate_dfns => aggregate_definitions(component_type, &
-                                                      subcomponent_type)
-    mf6_input%param_dfns => param_definitions(component_type, subcomponent_type)
+    ! -- set input definitions
+    mf6_input%block_dfns => block_definitions(mf6_input%component_type, &
+                                              mf6_input%subcomponent_type)
+    mf6_input%aggregate_dfns => aggregate_definitions(mf6_input%component_type, &
+                                                      mf6_input%subcomponent_type)
+    mf6_input%param_dfns => param_definitions(mf6_input%component_type, &
+                                              mf6_input%subcomponent_type)
   end function getModflowInput
 
+  function update_sc_type(filetype, filename, component_type, subcomponent_type) &
+    result(sc_type)
+    character(len=*), intent(in) :: component_type
+    character(len=*), intent(in) :: subcomponent_type
+    character(len=*), intent(in) :: filetype
+    character(len=*), intent(in) :: filename
+    ! -- result
+    character(len=LENPACKAGETYPE) :: sc_type
+    !
+    sc_type = subcomponent_type
+    !
+    select case (subcomponent_type)
+    case ('RCH', 'EVT', 'SCP')
+      sc_type = read_as_arrays(filetype, filename, component_type, &
+                               subcomponent_type)
+    case default
+    end select
+    !
+    ! -- return
+    return
+  end function update_sc_type
+
+  function read_as_arrays(filetype, filename, component_type, subcomponent_type) &
+    result(sc_type)
+    use ConstantsModule, only: LINELENGTH
+    use InputOutputModule, only: openfile, getunit
+    use BlockParserModule, only: BlockParserType
+    character(len=*), intent(in) :: component_type
+    character(len=*), intent(in) :: subcomponent_type
+    character(len=*), intent(in) :: filetype
+    character(len=*), intent(in) :: filename
+    ! -- result
+    character(len=LENPACKAGETYPE) :: sc_type
+    type(BlockParserType) :: parser
+    integer(I4B) :: ierr, inunit
+    logical(LGP) :: isfound
+    logical(LGP) :: endOfBlock
+    character(len=LINELENGTH) :: keyword
+    !
+    sc_type = subcomponent_type
+    !
+    inunit = getunit()
+    !
+    call openfile(inunit, 0, trim(adjustl(filename)), filetype, &
+                  'FORMATTED', 'SEQUENTIAL', 'OLD')
+    !
+    call parser%Initialize(inunit, 0)
+    !
+    ! -- get options block
+    call parser%GetBlock('OPTIONS', isfound, ierr, &
+                         supportOpenClose=.true., blockRequired=.false.)
+    !
+    ! -- parse options block if detected
+    if (isfound) then
+      do
+        call parser%GetNextLine(endOfBlock)
+        !
+        if (endOfBlock) exit
+        !
+        call parser%GetStringCaps(keyword)
+        !
+        if (keyword == 'READASARRAYS') then
+          write (sc_type, '(a)') trim(subcomponent_type)//'A'
+          exit
+        end if
+      end do
+    end if
+    !
+    call parser%clear()
+    !
+    ! -- return
+    return
+  end function read_as_arrays
+
 end module ModflowInputModule
diff --git a/src/Utilities/Idm/SourceCommon.f90 b/src/Utilities/Idm/SourceCommon.f90
new file mode 100644
index 00000000000..3ba4640a2bf
--- /dev/null
+++ b/src/Utilities/Idm/SourceCommon.f90
@@ -0,0 +1,436 @@
+!> @brief This module contains the SourceCommonModule
+!!
+!! This module contains source independent input
+!! processing helper routines.
+!!
+!<
+module SourceCommonModule
+
+  use KindModule, only: DP, I4B, LGP
+  use SimVariablesModule, only: errmsg
+  use ConstantsModule, only: LINELENGTH, LENMEMPATH, LENMODELNAME, LENFTYPE, &
+                             LENPACKAGETYPE, LENPACKAGENAME, LENCOMPONENTNAME
+  use SimModule, only: store_error, store_error_filename
+
+  implicit none
+  private
+  public :: package_source_type
+  public :: idm_component_type, idm_subcomponent_type, idm_subcomponent_name
+  public :: set_model_shape
+  public :: get_shape_from_string
+  public :: mem_allocate_naux
+  public :: file_ext
+  public :: ifind_charstr
+  public :: filein_fname
+
+contains
+
+  !> @brief source identifier from model namfile FNAME array
+  !!
+  !! Return the source type for a package listed in the
+  !! model nam file packages block FNAME field.
+  !!
+  !<
+  function package_source_type(sourcename) result(sourcetype)
+    ! -- modules
+    use InputOutputModule, only: upcase
+    ! -- dummy
+    character(len=*), intent(in) :: sourcename
+    ! -- result
+    character(len=LENPACKAGENAME) :: sourcetype
+    ! -- locals
+    !
+    sourcetype = sourcename
+    call upcase(sourcetype)
+    !
+    select case (sourcetype)
+    case default
+      sourcetype = 'MF6FILE'
+    end select
+    !
+    ! -- return
+    return
+  end function package_source_type
+
+  !> @brief component from package or model type
+  !!
+  !! Return the component type typically derived from package file type,
+  !! i.e. return GWF when input is GWF6. This function checks the
+  !! resultant commponent type and throws a terminating error if not
+  !! supported by IDM in some capacity.
+  !!
+  !<
+  function idm_component_type(component) result(component_type)
+    ! -- modules
+    use IdmDfnSelectorModule, only: idm_component
+    ! -- dummy
+    character(len=*), intent(in) :: component
+    ! -- return
+    character(len=LENCOMPONENTNAME) :: component_type
+    ! -- local
+    integer(I4B) :: i, ilen, idx
+    !
+    ! -- initialize
+    component_type = ''
+    idx = 0
+    !
+    ilen = len_trim(component)
+    do i = 1, ilen
+      if (component(i:i) == '6' .or. component(i:i) == '-') then
+      else
+        idx = idx + 1
+        component_type(idx:idx) = component(i:i)
+      end if
+    end do
+    !
+    if (.not. idm_component(component_type)) then
+      write (errmsg, '(a)') &
+        'IDP input error, unrecognized component: "'//trim(component)//'"'
+      call store_error(errmsg, .true.)
+    end if
+    !
+    ! -- return
+    return
+  end function idm_component_type
+
+  !> @brief component from package or model type
+  !!
+  !! Return the subcomponent type typically derived from package file type,
+  !! i.e. return CHD when input is CHD6. Note this function is called on
+  !! file types that are both idm integrated and not and should not set
+  !! an error based on this difference.
+  !!
+  !<
+  function idm_subcomponent_type(component, subcomponent) &
+    result(subcomponent_type)
+    ! -- modules
+    ! -- dummy
+    character(len=*), intent(in) :: component !< component, e.g. GWF6
+    character(len=*), intent(in) :: subcomponent !< subcomponent, e.g. CHD6
+    ! -- return
+    character(len=LENCOMPONENTNAME) :: subcomponent_type
+    ! -- local
+    character(len=LENCOMPONENTNAME) :: component_type
+    integer(I4B) :: i, ilen, idx
+    !
+    ! -- initialize
+    subcomponent_type = ''
+    idx = 0
+    !
+    ! -- verify component
+    component_type = idm_component_type(component)
+    !
+    ilen = len_trim(subcomponent)
+    do i = 1, ilen
+      if (subcomponent(i:i) == '6' .or. subcomponent(i:i) == '-') then
+      else
+        idx = idx + 1
+        subcomponent_type(idx:idx) = subcomponent(i:i)
+      end if
+    end do
+    !
+    ! -- return
+    return
+  end function idm_subcomponent_type
+
+  !> @brief model package subcomponent name
+  !!
+  !! Return the IDM component name, which is the pacage type for
+  !! base packages and the package name for mutli package (i.e.
+  !! stress) types.
+  !!
+  !<
+  function idm_subcomponent_name(component_type, subcomponent_type, sc_name) &
+    result(subcomponent_name)
+    ! -- modules
+    use IdmDfnSelectorModule, only: idm_multi_package
+    ! -- dummy
+    character(len=*), intent(in) :: component_type
+    character(len=*), intent(in) :: subcomponent_type
+    character(len=*), intent(in) :: sc_name
+    ! -- return
+    character(len=LENPACKAGENAME) :: subcomponent_name
+    ! -- local
+    !
+    subcomponent_name = ''
+    !
+    if (idm_multi_package(component_type, subcomponent_type)) then
+      !
+      subcomponent_name = sc_name
+    else
+      !
+      subcomponent_name = subcomponent_type
+    end if
+    !
+    ! -- return
+    return
+  end function idm_subcomponent_name
+
+  !> @brief input file extension
+  !!
+  !! Return the input file extension, or an empty string if
+  !! not identified.
+  !!
+  !<
+  function file_ext(filename) result(ext)
+    ! -- modules
+    use IdmDfnSelectorModule, only: idm_multi_package
+    ! -- dummy
+    character(len=*), intent(in) :: filename
+    ! -- return
+    character(len=LENPACKAGETYPE) :: ext
+    ! -- local
+    integer(I4B) :: i, istart, istop
+    !
+    ! -- initialize
+    ext = ''
+    istart = 0
+    istop = len_trim(filename)
+    !
+    ! -- identify '.' character position from back of string
+    do i = istop, 1, -1
+      if (filename(i:i) == '.') then
+        istart = i
+        exit
+      end if
+    end do
+    !
+    !
+    if (istart > 0) then
+      ext = filename(istart + 1:istop)
+    end if
+    !
+    ! -- return
+    return
+  end function file_ext
+
+  subroutine get_shape_from_string(shape_string, array_shape, memoryPath)
+    use InputOutputModule, only: parseline
+    use MemoryManagerModule, only: mem_setptr
+    character(len=*), intent(in) :: shape_string
+    integer(I4B), dimension(:), allocatable, intent(inout) :: array_shape
+    character(len=*), intent(in) :: memoryPath !< memorypath to put loaded information
+    integer(I4B) :: ndim
+    integer(I4B) :: i
+    integer(I4B), pointer :: int_ptr
+    character(len=16), dimension(:), allocatable :: array_shape_string
+    character(len=:), allocatable :: shape_string_copy
+    !
+    ! -- parse the string into multiple words
+    shape_string_copy = trim(shape_string)//' '
+    call ParseLine(shape_string_copy, ndim, array_shape_string)
+    allocate (array_shape(ndim))
+    !
+    ! -- find shape in memory manager and put into array_shape
+    do i = 1, ndim
+      call mem_setptr(int_ptr, array_shape_string(i), memoryPath)
+      array_shape(i) = int_ptr
+    end do
+    !
+    ! -- return
+    return
+  end subroutine get_shape_from_string
+
+  !> @brief routine for setting the model shape
+  !!
+  !! The model shape must be set in the memory manager because
+  !! individual packages need to know the shape of the arrays
+  !! to read.
+  !!
+  !<
+  subroutine set_model_shape(ftype, fname, model_mempath, dis_mempath, &
+                             model_shape)
+    use MemoryManagerModule, only: mem_allocate, mem_setptr, get_isize
+    character(len=*), intent(in) :: ftype
+    character(len=*), intent(in) :: fname
+    character(len=*), intent(in) :: model_mempath
+    character(len=*), intent(in) :: dis_mempath
+    integer(I4B), dimension(:), pointer, contiguous, intent(inout) :: model_shape
+    integer(I4B), pointer :: ndim1
+    integer(I4B), pointer :: ndim2
+    integer(I4B), pointer :: ndim3
+    integer(I4B), pointer :: ncelldim
+    integer(I4B) :: dim1_size, dim2_size, dim3_size
+    !
+    ! -- allocate and set model shape in model input context
+    select case (ftype)
+    case ('DIS6')
+      !
+      call get_isize('NLAY', dis_mempath, dim1_size)
+      call get_isize('NROW', dis_mempath, dim2_size)
+      call get_isize('NCOL', dis_mempath, dim3_size)
+      !
+      if (dim1_size <= 0) then
+        write (errmsg, '(a)') &
+          'Required input dimension "NLAY" not found.'
+        call store_error(errmsg)
+      end if
+      !
+      if (dim2_size <= 0) then
+        write (errmsg, '(a)') &
+          'Required input dimension "NROW" not found.'
+        call store_error(errmsg)
+      end if
+      !
+      if (dim3_size <= 0) then
+        write (errmsg, '(a)') &
+          'Required input dimension "NCOL" not found.'
+        call store_error(errmsg)
+      end if
+      !
+      if (dim1_size >= 1 .and. dim2_size >= 1 .and. dim3_size >= 1) then
+        call mem_allocate(model_shape, 3, 'MODEL_SHAPE', model_mempath)
+        call mem_setptr(ndim1, 'NLAY', dis_mempath)
+        call mem_setptr(ndim2, 'NROW', dis_mempath)
+        call mem_setptr(ndim3, 'NCOL', dis_mempath)
+        model_shape = [ndim1, ndim2, ndim3]
+      else
+        call store_error_filename(fname)
+      end if
+      !
+    case ('DISV6')
+      !
+      call get_isize('NLAY', dis_mempath, dim1_size)
+      call get_isize('NCPL', dis_mempath, dim2_size)
+      !
+      if (dim1_size <= 0) then
+        write (errmsg, '(a)') &
+          'Required input dimension "NLAY" not found.'
+        call store_error(errmsg)
+      end if
+      !
+      if (dim2_size <= 0) then
+        write (errmsg, '(a)') &
+          'Required input dimension "NCPL" not found.'
+        call store_error(errmsg)
+      end if
+      !
+      if (dim1_size >= 1 .and. dim2_size >= 1) then
+        call mem_allocate(model_shape, 2, 'MODEL_SHAPE', model_mempath)
+        call mem_setptr(ndim1, 'NLAY', dis_mempath)
+        call mem_setptr(ndim2, 'NCPL', dis_mempath)
+        model_shape = [ndim1, ndim2]
+      else
+        call store_error_filename(fname)
+      end if
+    case ('DISU6')
+      !
+      call get_isize('NODES', dis_mempath, dim1_size)
+      !
+      if (dim1_size <= 0) then
+        write (errmsg, '(a)') &
+          'Required input dimension "NODES" not found.'
+        call store_error(errmsg)
+        call store_error_filename(fname)
+      end if
+      !
+      call mem_allocate(model_shape, 1, 'MODEL_SHAPE', model_mempath)
+      call mem_setptr(ndim1, 'NODES', dis_mempath)
+      model_shape = [ndim1]
+    end select
+    !
+    ! -- allocate and set ncelldim in model input context
+    call mem_allocate(ncelldim, 'NCELLDIM', model_mempath)
+    ncelldim = size(model_shape)
+    !
+    ! -- return
+    return
+  end subroutine set_model_shape
+
+  subroutine mem_allocate_naux(mempath)
+    use MemoryManagerModule, only: mem_allocate, mem_setptr, get_isize
+    character(len=*), intent(in) :: mempath
+    integer(I4B), pointer :: naux => null()
+    integer(I4B) :: isize
+    !
+    ! -- allocate optional input scalars locally
+    call get_isize('NAUX', mempath, isize)
+    if (isize < 0) then
+      call mem_allocate(naux, 'NAUX', mempath)
+      naux = 0
+    end if
+    !
+    ! -- return
+    return
+  end subroutine mem_allocate_naux
+
+  function ifind_charstr(array, str)
+    use CharacterStringModule, only: CharacterStringType
+    ! -- Find the first array element containing str
+    ! -- Return -1 if not found.
+    implicit none
+    ! -- return
+    integer(I4B) :: ifind_charstr
+    ! -- dummy
+    type(CharacterStringType), dimension(:), intent(in) :: array
+    character(len=*) :: str
+    character(len=LINELENGTH) :: compare_str
+    ! -- local
+    integer(I4B) :: i
+    !
+    ! -- initialize
+    ifind_charstr = -1
+    !
+    findloop: do i = 1, size(array)
+      compare_str = array(i)
+      if (compare_str == str) then
+        ifind_charstr = i
+        exit findloop
+      end if
+    end do findloop
+    !
+    ! -- return
+    return
+  end function ifind_charstr
+
+  !> @brief enforce and set a single input filename provided via FILEIN keyword
+  !!
+  !! Set a FILEIN filename provided via an OPTIONS block.
+  !! Only use this function if a maximum of one FILEIN file name
+  !! string is expected.
+  !!
+  !! Return true if single FILEIN file name found and set, return
+  !! false if FILEIN tag not found.
+  !!
+  !<
+  function filein_fname(filename, tagname, input_mempath, input_fname) &
+    result(found)
+    use SimModule, only: store_error, store_error_filename
+    use MemoryManagerModule, only: mem_setptr, get_isize
+    use CharacterStringModule, only: CharacterStringType
+    character(len=*), intent(inout) :: filename
+    character(len=*), intent(in) :: tagname
+    character(len=*), intent(in) :: input_mempath
+    character(len=*), intent(in) :: input_fname
+    logical(LGP) :: found
+    type(CharacterStringType), dimension(:), pointer, &
+      contiguous :: fnames
+    integer(I4B) :: isize
+    !
+    ! -- initialize
+    found = .false.
+    filename = ''
+    !
+    call get_isize(tagname, input_mempath, isize)
+    !
+    if (isize > 0) then
+      !
+      if (isize /= 1) then
+        errmsg = 'Multiple FILEIN keywords detected for tag "'//trim(tagname)// &
+                 '" in OPTIONS block. Only one entry allowed.'
+        call store_error(errmsg)
+        call store_error_filename(input_fname)
+      end if
+      !
+      call mem_setptr(fnames, tagname, input_mempath)
+      !
+      filename = fnames(1)
+      found = .true.
+      !
+    end if
+    !
+    ! -- return
+    return
+  end function filein_fname
+
+end module SourceCommonModule
diff --git a/src/Utilities/Idm/SourceLoad.F90 b/src/Utilities/Idm/SourceLoad.F90
new file mode 100644
index 00000000000..a41a4393464
--- /dev/null
+++ b/src/Utilities/Idm/SourceLoad.F90
@@ -0,0 +1,254 @@
+!> @brief This module contains the SourceLoadModule
+!!
+!! This module contains the routines needed to generate
+!! a loader object for an input source and routines
+!! that distribute processing to a particular source.
+!!
+!<
+module SourceLoadModule
+
+  use KindModule, only: DP, I4B, LGP
+  use SimVariablesModule, only: errmsg
+  use ConstantsModule, only: LINELENGTH, LENMEMPATH, LENMODELNAME, LENFTYPE, &
+                             LENPACKAGETYPE, LENPACKAGENAME
+  use SimModule, only: store_error, store_error_filename
+  use ModflowInputModule, only: ModflowInputType, getModflowInput
+
+  implicit none
+  private
+  public :: create_input_loader
+  public :: open_source_file
+  public :: load_modelnam, load_simnam
+  public :: remote_model_ndim
+
+contains
+
+  !> @brief factory function to create and setup model package static loader
+  !<
+  function create_input_loader(component_type, subcomponent_type, &
+                               component_name, subcomponent_name, input_type, &
+                               input_fname, component_fname) result(loader)
+    use SourceCommonModule, only: package_source_type, idm_subcomponent_name
+    use InputLoadTypeModule, only: StaticPkgLoadBaseType
+    character(len=*), intent(in) :: component_type
+    character(len=*), intent(in) :: subcomponent_type
+    character(len=*), intent(in) :: component_name
+    character(len=*), intent(in) :: subcomponent_name
+    character(len=*), intent(in) :: input_type
+    character(len=*), intent(in) :: input_fname
+    character(len=*), intent(in) :: component_fname
+    class(StaticPkgLoadBaseType), pointer :: loader
+    type(ModflowInputType) :: mf6_input
+    character(len=LENPACKAGENAME) :: source_type
+    character(len=LENPACKAGENAME) :: sc_name
+    !
+    ! -- set subcomponent name
+    sc_name = idm_subcomponent_name(component_type, subcomponent_type, &
+                                    subcomponent_name)
+    !
+    ! -- create description of input
+    mf6_input = getModflowInput(input_type, component_type, subcomponent_type, &
+                                component_name, sc_name, input_fname)
+    !
+    ! -- set package source
+    source_type = package_source_type(input_fname)
+    !
+    ! -- set source loader for model package
+    loader => package_loader(source_type)
+    !
+    ! -- initialize loader
+    call loader%init(mf6_input, component_name, component_fname, input_fname)
+    !
+    ! -- return
+    return
+  end function create_input_loader
+
+  !> @brief allocate source model package static loader
+  !<
+  function package_loader(source_type) result(loader)
+    use InputLoadTypeModule, only: StaticPkgLoadBaseType
+    use IdmMf6FileModule, only: Mf6FileStaticPkgLoadType
+    character(len=*), intent(inout) :: source_type
+    class(Mf6FileStaticPkgLoadType), pointer :: mf6file_loader
+    class(StaticPkgLoadBaseType), pointer :: loader
+    !
+    ! -- initialize
+    nullify (loader)
+    !
+    ! -- allocate derived object
+    select case (source_type)
+    case ('MF6FILE')
+      allocate (mf6file_loader)
+      loader => mf6file_loader
+    case default
+      write (errmsg, '(a)') &
+        'Simulation package input source type "'//trim(source_type)// &
+        '" not currently supported.'
+      call store_error(errmsg, .true.)
+    end select
+    !
+    ! -- return
+    return
+  end function package_loader
+
+  function open_source_file(pkgtype, filename, modelfname, iout) result(fd)
+    use SourceCommonModule, only: package_source_type
+    use IdmMf6FileModule, only: open_mf6file
+    character(len=*), intent(in) :: pkgtype
+    character(len=*), intent(in) :: filename
+    character(len=*), intent(in) :: modelfname
+    integer(I4B), intent(in) :: iout
+    integer(I4B) :: fd
+    character(len=LENPACKAGENAME) :: source_type
+    !
+    ! -- initialize
+    fd = 0
+    !
+    ! -- set source type
+    source_type = package_source_type(filename)
+    !
+    select case (source_type)
+    case ('MF6FILE')
+      fd = open_mf6file(pkgtype, filename, modelfname, iout)
+    case default
+    end select
+    !
+    ! -- return
+    return
+  end function open_source_file
+
+  subroutine load_modelnam(mtype, mfname, mname, iout)
+    use SimVariablesModule, only: simfile
+    use SourceCommonModule, only: package_source_type, idm_component_type
+    use IdmMf6FileModule, only: input_load
+    character(len=*), intent(in) :: mtype
+    character(len=*), intent(in) :: mfname
+    character(len=*), intent(in) :: mname
+    integer(I4B), intent(in) :: iout
+    type(ModflowInputType) :: mf6_input
+    character(len=LENPACKAGENAME) :: source_type
+    !
+    ! -- set source type
+    source_type = package_source_type(mfname)
+    !
+    ! -- create description of input
+    mf6_input = getModflowInput(mtype, idm_component_type(mtype), 'NAM', &
+                                mname, 'NAM', mfname)
+    !
+    select case (source_type)
+    case ('MF6FILE')
+      call input_load(mfname, mf6_input, simfile, iout)
+    case default
+    end select
+    !
+    ! -- return
+    return
+  end subroutine load_modelnam
+
+  subroutine load_simnam()
+    use SimVariablesModule, only: simfile, iout
+    use MessageModule, only: write_message
+    use IdmMf6FileModule, only: input_load
+    type(ModflowInputType) :: mf6_input
+    character(len=LINELENGTH) :: line
+    logical :: lexist
+    !
+    ! -- load mfsim.nam if it exists
+    inquire (file=trim(adjustl(simfile)), exist=lexist)
+    !
+    if (lexist) then
+      !
+      ! -- write name of namfile to stdout
+      write (line, '(2(1x,a))') 'Using Simulation name file:', &
+        trim(adjustl(simfile))
+      call write_message(line, skipafter=1)
+      !
+      ! -- create description of input
+      mf6_input = getModflowInput('NAM6', 'SIM', 'NAM', 'SIM', 'NAM', simfile)
+      !
+      ! -- open namfile and load to input context
+      call input_load(simfile, mf6_input, simfile, iout)
+    end if
+    !
+    ! -- return
+    return
+  end subroutine load_simnam
+
+  function remote_model_ndim(mtype, mfname) result(ncelldim)
+    use SourceCommonModule, only: package_source_type
+    use ConstantsModule, only: LINELENGTH
+    use InputOutputModule, only: openfile, getunit
+    use BlockParserModule, only: BlockParserType
+    character(len=*), intent(in) :: mtype
+    character(len=*), intent(in) :: mfname
+    integer(I4B) :: ncelldim
+    character(len=LENPACKAGENAME) :: source_type
+    type(BlockParserType) :: parser
+    integer(I4B) :: ierr, inunit
+    logical(LGP) :: isfound, endOfBlock
+    character(len=LINELENGTH) :: ptype
+    !
+    ! -- initialize
+    ncelldim = 0
+    !
+    ! -- set source type
+    source_type = package_source_type(mfname)
+    !
+    select case (source_type)
+    case ('MF6FILE')
+      !
+      ! -- open name file
+      inunit = getunit()
+      call openfile(inunit, 0, trim(adjustl(mfname)), mtype, &
+                    'FORMATTED', 'SEQUENTIAL', 'OLD')
+      !
+      ! -- initialize parser
+      call parser%Initialize(inunit, 0)
+      !
+      ! -- get options block
+      call parser%GetBlock('OPTIONS', isfound, ierr, &
+                           supportOpenClose=.true., blockRequired=.false.)
+      ! -- iterate through options
+      if (isfound) then
+        do
+          call parser%GetNextLine(endOfBlock)
+          if (endOfBlock) exit
+        end do
+      end if
+      !
+      ! -- get packages block
+      call parser%GetBlock('PACKAGES', isfound, ierr, &
+                           supportOpenClose=.true., blockRequired=.true.)
+      if (isfound) then
+        ! -- read through packages
+        do
+          call parser%GetNextLine(endOfBlock)
+          if (endOfBlock) exit
+          !
+          call parser%GetStringCaps(ptype)
+          !
+          select case (ptype)
+          case ('DIS6')
+            ncelldim = 3
+            exit
+          case ('DISV6')
+            ncelldim = 2
+            exit
+          case ('DISU6')
+            ncelldim = 1
+            exit
+          case default
+          end select
+        end do
+      end if
+      !
+      call parser%clear()
+      !
+    case default
+    end select
+    !
+    ! -- return
+    return
+  end function remote_model_ndim
+
+end module SourceLoadModule
diff --git a/src/Utilities/Idm/mf6blockfile/AsciiInputLoadType.f90 b/src/Utilities/Idm/mf6blockfile/AsciiInputLoadType.f90
new file mode 100644
index 00000000000..081f31f1579
--- /dev/null
+++ b/src/Utilities/Idm/mf6blockfile/AsciiInputLoadType.f90
@@ -0,0 +1,34 @@
+!> @brief This module contains the AsciiInputLoadTypeModule
+!!
+!! This module defines an abstract type that support generic
+!! IDP dynamic input loading for traditional MODFLOW 6 ascii
+!! files.
+!!
+!<
+module AsciiInputLoadTypeModule
+
+  use KindModule, only: DP, I4B, LGP
+  use InputLoadTypeModule, only: DynamicPkgLoadType
+  use BlockParserModule, only: BlockParserType
+
+  implicit none
+  private
+  public :: AsciiDynamicPkgLoadBaseType
+
+  !> @brief base abstract type for ascii source dynamic load
+  !!
+  !<
+  type, abstract, extends(DynamicPkgLoadType) :: AsciiDynamicPkgLoadBaseType
+  contains
+    procedure(ascii_period_load_if), deferred :: rp
+  end type AsciiDynamicPkgLoadBaseType
+
+  abstract interface
+    subroutine ascii_period_load_if(this, parser)
+      import AsciiDynamicPkgLoadBaseType, BlockParserType
+      class(AsciiDynamicPkgLoadBaseType), intent(inout) :: this
+      type(BlockParserType), pointer, intent(inout) :: parser !< block parser
+    end subroutine
+  end interface
+
+end module AsciiInputLoadTypeModule
diff --git a/src/Utilities/Idm/mf6blockfile/IdmMf6File.f90 b/src/Utilities/Idm/mf6blockfile/IdmMf6File.f90
index 4e844c23fed..365cafcdefb 100644
--- a/src/Utilities/Idm/mf6blockfile/IdmMf6File.f90
+++ b/src/Utilities/Idm/mf6blockfile/IdmMf6File.f90
@@ -1,25 +1,31 @@
 !> @brief This module contains the IdmMf6FileModule
 !!
-!! This module contains the high-level routines for loading
-!! a MODFLOW input file to the input context.
+!! This module contains high-level routines for loading
+!! MODFLOW 6 ASCII source input.
 !!
 !<
 module IdmMf6FileModule
 
   use KindModule, only: DP, I4B, LGP
+  use SimVariablesModule, only: errmsg
   use ConstantsModule, only: LINELENGTH, LENMEMPATH, LENMODELNAME, &
-                             LENPACKAGENAME, LENFTYPE, LENPACKAGETYPE
+                             LENPACKAGENAME, LENFTYPE, LENPACKAGETYPE, &
+                             LENAUXNAME, LENBOUNDNAME, LENTIMESERIESNAME, &
+                             LENLISTLABEL, LENVARNAME, DNODATA, &
+                             DZERO, IZERO
   use SimModule, only: store_error, store_error_filename
   use InputOutputModule, only: openfile, getunit
   use BlockParserModule, only: BlockParserType
   use ModflowInputModule, only: ModflowInputType, getModflowInput
   use CharacterStringModule, only: CharacterStringType
-  use ModelPackageInputsModule, only: ModelPackageInputsType
+  use InputLoadTypeModule, only: StaticPkgLoadBaseType, DynamicPkgLoadBaseType
+  use AsciiInputLoadTypeModule, only: AsciiDynamicPkgLoadBaseType
 
   implicit none
   private
-  public :: input_load ! TODO: remove
-  public :: load_models_mf6
+  public :: input_load
+  public :: Mf6FileStaticPkgLoadType, Mf6FileDynamicPkgLoadType
+  public :: open_mf6file
 
   !> @brief derived type for storing package loader
   !!
@@ -39,11 +45,38 @@ subroutine IPackageLoad(parser, mf6_input, iout)
       use BlockParserModule, only: BlockParserType
       use ModflowInputModule, only: ModflowInputType
       type(BlockParserType), intent(inout) :: parser !< block parser
-      type(ModflowInputType), intent(in) :: mf6_input !< ModflowInputType object that describes the input
+      type(ModflowInputType), intent(in) :: mf6_input !< description of input
       integer(I4B), intent(in) :: iout !< unit number for output
     end subroutine IPackageLoad
   end interface
 
+  !> @brief MF6File static loader derived type
+  !<
+  type, extends(StaticPkgLoadBaseType) :: Mf6FileStaticPkgLoadType
+  contains
+    procedure :: init => static_init
+    procedure :: load => static_load
+    procedure :: destroy => static_destroy
+  end type Mf6FileStaticPkgLoadType
+
+  !> @brief MF6File dynamic loader derived type
+  !<
+  type, extends(DynamicPkgLoadBaseType) :: Mf6FileDynamicPkgLoadType
+    type(BlockParserType), pointer :: parser !< parser for MF6File period blocks
+    integer(I4B), pointer :: iper => null()
+    integer(I4B), pointer :: ionper => null()
+    class(AsciiDynamicPkgLoadBaseType), pointer :: block_loader => null()
+  contains
+    procedure :: init => dynamic_init
+    procedure :: df => dynamic_df
+    procedure :: ad => dynamic_ad
+    procedure :: set => dynamic_set
+    procedure :: rp => dynamic_rp
+    procedure :: read_ionper => dynamic_read_ionper
+    procedure :: create_loader => dynamic_create_loader
+    procedure :: destroy => dynamic_destroy
+  end type Mf6FileDynamicPkgLoadType
+
 contains
 
   !> @brief generic procedure to MODFLOW 6 load routine
@@ -51,286 +84,369 @@ end subroutine IPackageLoad
   subroutine generic_mf6_load(parser, mf6_input, iout)
     use LoadMf6FileModule, only: idm_load
     type(BlockParserType), intent(inout) :: parser !< block parser
-    type(ModflowInputType), intent(in) :: mf6_input !< ModflowInputType object that describes the input
+    type(ModflowInputType), intent(in) :: mf6_input !< description of input
     integer(I4B), intent(in) :: iout !< unit number for output
 
-    call idm_load(parser, mf6_input%pkgtype, &
-                  mf6_input%component_type, mf6_input%subcomponent_type, &
-                  mf6_input%component_name, mf6_input%subcomponent_name, &
-                  iout)
+    call idm_load(parser, mf6_input, iout)
 
   end subroutine generic_mf6_load
 
   !> @brief input load for traditional mf6 simulation input file
   !<
-  subroutine input_load(pkgtype, &
-                        component_type, subcomponent_type, &
-                        component_name, subcomponent_name, &
-                        inunit, iout)
-    character(len=*), intent(in) :: pkgtype !< pkgtype to load, such as DIS6, DISV6, NPF6
-    character(len=*), intent(in) :: component_type !< component type, such as GWF or GWT
-    character(len=*), intent(in) :: subcomponent_type !< subcomponent type, such as DIS or NPF
-    character(len=*), intent(in) :: component_name !< component name, such as MYGWFMODEL
-    character(len=*), intent(in) :: subcomponent_name !< subcomponent name, such as MYWELLPACKAGE
-    integer(I4B), intent(in) :: inunit !< unit number for input
+  subroutine input_load(filename, mf6_input, component_filename, iout, &
+                        mf6_parser)
+    character(len=*), intent(in) :: filename
+    type(ModflowInputType), intent(in) :: mf6_input
+    character(len=*), intent(in) :: component_filename !< component (e.g. model) filename
     integer(I4B), intent(in) :: iout !< unit number for output
-    type(BlockParserType), allocatable :: parser !< block parser
-    type(ModflowInputType) :: mf6_input
+    type(BlockParserType), pointer, optional, intent(inout) :: mf6_parser
+    type(BlockParserType), allocatable, target :: parser !< block parser
     type(PackageLoad) :: pkgloader
+    integer(I4B) :: inunit
     !
-    ! -- create description of input
-    mf6_input = getModflowInput(pkgtype, component_type, &
-                                subcomponent_type, component_name, &
-                                subcomponent_name)
-    !
-    ! -- set mf6 parser based package loader by file type
-    select case (pkgtype)
+    ! -- set parser based package loader by file type
+    select case (mf6_input%pkgtype)
     case default
+      !
+      ! -- open input file
+      inunit = open_mf6file(mf6_input%pkgtype, filename, component_filename, iout)
+      !
+      ! -- allocate and initialize parser
       allocate (parser)
       call parser%Initialize(inunit, iout)
+      !
+      ! -- set load interface
       pkgloader%load_package => generic_mf6_load
+      !
     end select
     !
     ! -- invoke the selected load routine
     call pkgloader%load_package(parser, mf6_input, iout)
     !
-    ! -- close files and deallocate
-    if (allocated(parser)) then
-      !call parser%clear()
-      deallocate (parser)
+    ! -- generate a dynamic loader parser if requested
+    if (present(mf6_parser)) then
+      !
+      ! -- create dynamic parser
+      allocate (mf6_parser, source=parser)
+    else
+      !
+      ! -- clear parser file handles
+      call parser%clear()
     end if
     !
+    ! -- cleanup
+    deallocate (parser)
+    !
     ! -- return
     return
   end subroutine input_load
 
-  !> @brief input load model idm supported package files
+  !> @brief static loader init
   !<
-  subroutine load_model_pkgfiles(model_pkg_inputs, iout)
-    ! -- modules
-    use IdmDfnSelectorModule, only: idm_integrated, idm_multi_package
-    ! -- dummy
-    type(ModelPackageInputsType), intent(inout) :: model_pkg_inputs
+  subroutine static_init(this, mf6_input, component_name, component_input_name, &
+                         input_name)
+    class(Mf6FileStaticPkgLoadType), intent(inout) :: this
+    type(ModflowInputType), intent(in) :: mf6_input
+    character(len=*), intent(in) :: component_name
+    character(len=*), intent(in) :: component_input_name
+    character(len=*), intent(in) :: input_name
+    !
+    call this%StaticPkgLoadType%init(mf6_input, component_name, &
+                                     component_input_name, input_name)
+    !
+  end subroutine static_init
+
+  !> @brief load routine for static loader
+  !<
+  function static_load(this, iout) result(period_loader)
+    class(Mf6FileStaticPkgLoadType), intent(inout) :: this
     integer(I4B), intent(in) :: iout
-    ! -- locals
-    integer(I4B) :: n, m
-    character(len=LENPACKAGETYPE) :: pkgtype
-    character(len=LENPACKAGENAME) :: sc_name
+    class(DynamicPkgLoadBaseType), pointer :: period_loader
+    class(Mf6FileDynamicPkgLoadType), pointer :: mf6_loader => null()
+    type(BlockParserType), pointer :: parser => null()
+    !
+    ! -- initialize
+    nullify (period_loader)
     !
-    do n = 1, size(model_pkg_inputs%pkglist)
+    ! -- load model package to input context
+    if (this%iperblock > 0) then
+      !
+      ! -- package is dynamic, allocate loader
+      allocate (mf6_loader)
+      !
+      ! -- load static input
+      call input_load(this%input_name, this%mf6_input, &
+                      this%component_input_name, iout, parser)
+      !
+      ! -- initialize dynamic loader
+      call mf6_loader%init(this%mf6_input, this%component_name, &
+                           this%component_input_name, this%input_name, &
+                           this%iperblock, iout)
+      !
+      ! -- set parser
+      call mf6_loader%set(parser)
       !
-      ! -- this list package type
-      pkgtype = model_pkg_inputs%pkglist(n)%pkgtype
+      ! -- set return pointer to base dynamic loader
+      period_loader => mf6_loader
       !
-      ! -- load all idm integrated package type file instances
-      do m = 1, model_pkg_inputs%pkglist(n)%pnum
-        !
-        if (idm_integrated(model_pkg_inputs%component_type, &
-                           model_pkg_inputs%pkglist(n)%component_type)) then
-          !
-          ! -- set subcomponent name
-          if (idm_multi_package(model_pkg_inputs%component_type, &
-                                model_pkg_inputs%pkglist(n)%component_type)) then
-            !
-            sc_name = model_pkg_inputs%pkglist(n)%pkgnames(m)
-          else
-            !
-            sc_name = model_pkg_inputs%pkglist(n)%component_type
-          end if
-          !
-          ! -- load model package to input context
-          call input_load(pkgtype, model_pkg_inputs%component_type, &
-                          model_pkg_inputs%pkglist(n)%component_type, &
-                          model_pkg_inputs%modelname, sc_name, &
-                          model_pkg_inputs%pkglist(n)%inunits(m), iout)
-          !
-          ! -- close file and update unit number
-          close (model_pkg_inputs%pkglist(n)%inunits(m))
-          model_pkg_inputs%pkglist(n)%inunits(m) = 0
-          !
-        else
-          ! Not an IDM supported package, leave inunit open
-        end if
-      end do
-    end do
+    else
+      !
+      ! -- load static input
+      call input_load(this%input_name, this%mf6_input, &
+                      this%component_input_name, iout)
+    end if
     !
     ! -- return
     return
-  end subroutine load_model_pkgfiles
+  end function static_load
 
-  !> @brief open all model package files
+  !> @brief static loader destroy
   !<
-  subroutine open_model_pkgfiles(model_pkg_inputs, iout)
-    ! -- modules
-    ! -- dummy
-    type(ModelPackageInputsType), intent(inout) :: model_pkg_inputs
+  subroutine static_destroy(this)
+    class(Mf6FileStaticPkgLoadType), intent(inout) :: this
+    !
+    call this%StaticPkgLoadType%destroy()
+    !
+  end subroutine static_destroy
+
+  !> @brief dynamic loader init
+  !<
+  subroutine dynamic_init(this, mf6_input, modelname, modelfname, source, &
+                          iperblock, iout)
+    use InputDefinitionModule, only: InputParamDefinitionType
+    use DefinitionSelectModule, only: get_param_definition_type
+    use MemoryManagerModule, only: mem_allocate
+    class(Mf6FileDynamicPkgLoadType), intent(inout) :: this
+    type(ModflowInputType), intent(in) :: mf6_input
+    character(len=*), intent(in) :: modelname
+    character(len=*), intent(in) :: modelfname
+    character(len=*), intent(in) :: source
+    integer(I4B), intent(in) :: iperblock
     integer(I4B), intent(in) :: iout
-    ! -- locals
-    integer(I4B) :: n, m
-    character(len=LINELENGTH) :: filename
-    character(len=LENPACKAGETYPE) :: filetype
-    character(len=LINELENGTH) :: errmsg
     !
-    do n = 1, size(model_pkg_inputs%pkglist)
-      !
-      ! -- this package type
-      filetype = model_pkg_inputs%pkglist(n)%pkgtype
-      !
-      ! -- open each package type file instance
-      do m = 1, model_pkg_inputs%pkglist(n)%pnum
-        !
-        ! -- set filename
-        filename = model_pkg_inputs%pkglist(n)%filenames(m)
-        !
-        if (filename /= '') then
-          !
-          ! -- get unit number, update object and open file
-          model_pkg_inputs%pkglist(n)%inunits(m) = getunit()
-          call openfile(model_pkg_inputs%pkglist(n)%inunits(m), iout, &
-                        trim(adjustl(filename)), filetype, 'FORMATTED', &
-                        'SEQUENTIAL', 'OLD')
-          !
-        else
-          write (errmsg, '(a,a,a,a,a)') &
-            'Package file unspecified, cannot load model package &
-            &[model=', trim(model_pkg_inputs%modelname), &
-            ', type=', trim(filetype), '].'
-          call store_error(errmsg)
-          call store_error_filename(model_pkg_inputs%modelfname)
-        end if
-      end do
-    end do
-    !
-    ! -- returh
+    call this%DynamicPkgLoadType%init(mf6_input, modelname, modelfname, &
+                                      source, iperblock, iout)
+    !
+    call mem_allocate(this%iper, 'IPER', this%mf6_input%mempath)
+    call mem_allocate(this%ionper, 'IONPER', this%mf6_input%mempath)
+    !
+    this%iper = 0
+    this%ionper = 0
+    !
+    ! -- allocate and initialize loader
+    call this%create_loader()
+    !
+    ! -- return
+    return
+  end subroutine dynamic_init
+
+  !> @brief dynamic loader set parser object
+  !<
+  subroutine dynamic_set(this, parser)
+    use InputDefinitionModule, only: InputParamDefinitionType
+    use DefinitionSelectModule, only: get_param_definition_type
+    class(Mf6FileDynamicPkgLoadType), intent(inout) :: this
+    type(BlockParserType), pointer, intent(inout) :: parser
+    !
+    ! -- set the parser
+    this%parser => parser
+    !
+    ! -- return
+    return
+  end subroutine dynamic_set
+
+  !> @brief define routine for dynamic loader
+  !<
+  subroutine dynamic_df(this)
+    class(Mf6FileDynamicPkgLoadType), intent(inout) :: this
+    !
+    ! -- read first iper
+    call this%read_ionper()
+    !
+    call this%block_loader%df()
+    !
+    ! -- return
     return
-  end subroutine open_model_pkgfiles
+  end subroutine dynamic_df
 
-  !> @brief load and make pkg info available to models
+  !> @brief advance routine for dynamic loader
   !<
-  subroutine modelpkgs_load(mtype, mfname, mname, iout)
+  subroutine dynamic_ad(this)
+    class(Mf6FileDynamicPkgLoadType), intent(inout) :: this
+    !
+    call this%block_loader%ad()
+    !
+    ! -- return
+    return
+  end subroutine dynamic_ad
+
+  !> @brief read and prepare routine for dynamic loader
+  !<
+  subroutine dynamic_rp(this)
     ! -- modules
+    use TdisModule, only: kper, nper
+    use MemoryManagerModule, only: mem_setptr
     ! -- dummy
-    character(len=*), intent(in) :: mtype
-    character(len=*), intent(in) :: mfname
-    character(len=*), intent(in) :: mname
-    integer(I4B), intent(in) :: iout
+    class(Mf6FileDynamicPkgLoadType), intent(inout) :: this
     ! -- locals
-    type(ModelPackageInputsType) :: model_pkg_inputs
-    !
-    ! -- set baseline state for model package instances
-    call model_pkg_inputs%init(mtype, mfname, mname, iout)
     !
-    ! -- open model package files
-    call open_model_pkgfiles(model_pkg_inputs, iout)
+    ! -- check if ready to load
+    if (this%ionper /= kper) return
     !
-    ! -- load model idm integrated package files
-    call load_model_pkgfiles(model_pkg_inputs, iout)
+    ! -- dynamic load
+    call this%block_loader%rp(this%parser)
     !
-    ! -- load descriptions of packages to model input context
-    call model_pkg_inputs%memload()
+    ! -- update loaded iper
+    this%iper = kper
     !
-    ! -- cleanup
-    call model_pkg_inputs%destroy()
+    ! -- read next iper
+    if (kper < nper) then
+      call this%read_ionper()
+    else
+      this%ionper = nper + 1
+    end if
     !
     ! -- return
     return
-  end subroutine modelpkgs_load
+  end subroutine dynamic_rp
 
-  !> @brief input load a single model namfile and model package files
+  !> @brief dynamic loader read ionper of next period block
   !<
-  subroutine model_load(mtype, mfname, mname, iout)
+  subroutine dynamic_read_ionper(this)
     ! -- modules
-    use SimVariablesModule, only: simfile
+    use TdisModule, only: kper, nper
     ! -- dummy
-    character(len=*), intent(in) :: mtype
-    character(len=*), intent(in) :: mfname
-    character(len=*), intent(in) :: mname
-    integer(I4B), intent(in) :: iout
+    class(Mf6FileDynamicPkgLoadType), intent(inout) :: this
     ! -- locals
-    character(len=LINELENGTH) :: errmsg
-    integer(I4B) :: inunit
+    character(len=LINELENGTH) :: line
+    logical(LGP) :: isblockfound
+    integer(I4B) :: ierr
+    character(len=*), parameter :: fmtblkerr = &
+      &"('Looking for BEGIN PERIOD iper.  Found ', a, ' instead.')"
     !
-    ! -- open namfile
-    inunit = getunit()
-    call openfile(inunit, iout, trim(mfname), 'NAM')
+    call this%parser%GetBlock('PERIOD', isblockfound, ierr, &
+                              supportOpenClose=.true., &
+                              blockRequired=.false.)
     !
-    select case (mtype)
-    case ('GWF6')
+    ! -- set first period block IPER
+    if (isblockfound) then
       !
-      ! -- load model namfile to the input context
-      call input_load('GWF6', 'GWF', 'NAM', mname, 'NAM', inunit, iout)
+      this%ionper = this%parser%GetInteger()
       !
-      ! -- load and create descriptions of model package files
-      call modelpkgs_load(mtype, mfname, mname, iout)
-      !
-    case ('GWT6')
-      !
-      call input_load('GWT6', 'GWT', 'NAM', mname, 'NAM', inunit, iout)
+      if (this%ionper <= this%iper) then
+        write (errmsg, '(a, i0, a, i0, a, i0, a)') &
+          'Error in stress period ', kper, &
+          '. Period numbers not increasing.  Found ', this%ionper, &
+          ' but last period block was assigned ', this%iper, '.'
+        call store_error(errmsg)
+        call this%parser%StoreErrorUnit()
+      end if
       !
-      call modelpkgs_load(mtype, mfname, mname, iout)
+    else
       !
-    case default
-      write (errmsg, '(a,a,a,a,a)') &
-        'Unknown simulation model type &
-        &[model=', trim(mname), &
-        ', type=', trim(mtype), '].'
-      call store_error(errmsg)
-      call store_error_filename(simfile)
-    end select
+      ! -- PERIOD block not found
+      if (ierr < 0) then
+        ! -- End of file found; data applies for remainder of simulation.
+        this%ionper = nper + 1
+      else
+        ! -- Found invalid block
+        call this%parser%GetCurrentLine(line)
+        write (errmsg, fmtblkerr) adjustl(trim(line))
+        call store_error(errmsg)
+        call this%parser%StoreErrorUnit()
+      end if
+    end if
     !
-    ! -- close namfile
-    close (inunit)
+    ! -- return
+    return
+  end subroutine dynamic_read_ionper
+
+  !> @brief allocate a dynamic loader based on load context
+  !<
+  subroutine dynamic_create_loader(this)
+    use StressListInputModule, only: StressListInputType
+    use StressGridInputModule, only: StressGridInputType
+    ! -- dummy
+    class(Mf6FileDynamicPkgLoadType), intent(inout) :: this
+    class(StressListInputType), pointer :: list_loader
+    class(StressGridInputType), pointer :: grid_loader
+    !
+    ! -- allocate and set loader
+    if (this%readasarrays) then
+      allocate (grid_loader)
+      this%block_loader => grid_loader
+    else
+      allocate (list_loader)
+      this%block_loader => list_loader
+    end if
+    !
+    ! -- initialize loader
+    call this%block_loader%init(this%mf6_input, &
+                                this%modelname, &
+                                this%modelfname, &
+                                this%sourcename, &
+                                this%iperblock, &
+                                this%iout)
     !
     ! -- return
     return
-  end subroutine model_load
+  end subroutine dynamic_create_loader
 
-  !> @brief input load model namfiles and model package files
+  !> @brief dynamic loader destroy
   !<
-  subroutine load_models_mf6(model_loadmask, iout)
+  subroutine dynamic_destroy(this)
+    class(Mf6FileDynamicPkgLoadType), intent(inout) :: this
+    !
+    ! -- deallocate input context
+    !call this%DynamicPkgLoadType%destroy()
+    !
+    ! -- deallocate loader
+    call this%block_loader%destroy()
+    deallocate (this%block_loader)
+    !
+    ! -- deallocate parser
+    call this%parser%clear()
+    deallocate (this%parser)
+    !
+    ! -- deallocate input context
+    call this%DynamicPkgLoadType%destroy()
+    !
+    ! -- return
+    return
+  end subroutine dynamic_destroy
+
+  !> @brief open a model package files
+  !<
+  function open_mf6file(filetype, filename, component_fname, iout) result(inunit)
     ! -- modules
-    use MemoryHelperModule, only: create_mem_path
-    use MemoryManagerModule, only: mem_setptr
-    use CharacterStringModule, only: CharacterStringType
-    use SimVariablesModule, only: idm_context
     ! -- dummy
-    integer(I4B), dimension(:), intent(in) :: model_loadmask
+    character(len=*), intent(in) :: filetype
+    character(len=*), intent(in) :: filename
+    character(len=*), intent(in) :: component_fname
     integer(I4B), intent(in) :: iout
+    ! -- return
+    integer(I4B) :: inunit
     ! -- locals
-    character(len=LENMEMPATH) :: input_mempath
-    type(CharacterStringType), dimension(:), contiguous, &
-      pointer :: mtypes !< model types
-    type(CharacterStringType), dimension(:), contiguous, &
-      pointer :: mfnames !< model file names
-    type(CharacterStringType), dimension(:), contiguous, &
-      pointer :: mnames !< model names
-    character(len=LINELENGTH) :: mtype, mfname
-    character(len=LENMODELNAME) :: mname
-    integer(I4B) :: n
-    !
-    ! -- set input memory path
-    input_mempath = create_mem_path('SIM', 'NAM', idm_context)
-    !
-    ! -- set pointers to input context model attribute arrays
-    call mem_setptr(mtypes, 'MTYPE', input_mempath)
-    call mem_setptr(mfnames, 'MFNAME', input_mempath)
-    call mem_setptr(mnames, 'MNAME', input_mempath)
-    !
-    do n = 1, size(mtypes)
-      !
-      ! -- attributes for this model
-      mtype = mtypes(n)
-      mfname = mfnames(n)
-      mname = mnames(n)
+    !
+    ! -- initialize
+    inunit = 0
+    !
+    if (filename /= '') then
       !
-      ! -- load model namfile
-      if (model_loadmask(n) > 0) then
-        call model_load(mtype, mfname, mname, iout)
-      end if
-    end do
+      ! -- get unit number, update object and open file
+      inunit = getunit()
+      call openfile(inunit, iout, trim(adjustl(filename)), filetype, &
+                    'FORMATTED', 'SEQUENTIAL', 'OLD')
+    else
+      write (errmsg, '(a,a,a)') &
+        'File unspecified, cannot load model or package &
+        &type "', trim(filetype), '".'
+      call store_error(errmsg)
+      call store_error_filename(component_fname)
+    end if
     !
     ! -- return
     return
-  end subroutine load_models_mf6
+  end function open_mf6file
 
 end module IdmMf6FileModule
diff --git a/src/Utilities/Idm/mf6blockfile/LoadMf6File.f90 b/src/Utilities/Idm/mf6blockfile/LoadMf6File.f90
index 41c7d84b622..bd33599f244 100644
--- a/src/Utilities/Idm/mf6blockfile/LoadMf6File.f90
+++ b/src/Utilities/Idm/mf6blockfile/LoadMf6File.f90
@@ -8,9 +8,9 @@
 module LoadMf6FileModule
 
   use KindModule, only: DP, I4B, LGP
-  use ConstantsModule, only: LINELENGTH, LENMEMPATH, LENVARNAME
   use SimVariablesModule, only: errmsg
   use SimModule, only: store_error
+  use ConstantsModule, only: LINELENGTH, LENMEMPATH, LENVARNAME
   use BlockParserModule, only: BlockParserType
   use LayeredArrayReaderModule, only: read_dbl1d_layered, &
                                       read_dbl2d_layered, &
@@ -43,29 +43,17 @@ module LoadMf6FileModule
   !! memory context location of the memory manager.
   !!
   !<
-  subroutine idm_load(parser, pkgtype, &
-                      component_type, subcomponent_type, &
-                      component_name, subcomponent_name, &
-                      iout)
+  subroutine idm_load(parser, mf6_input, iout)
     use SimVariablesModule, only: idm_context
+    use SourceCommonModule, only: set_model_shape, mem_allocate_naux
     type(BlockParserType), intent(inout) :: parser !< block parser
-    character(len=*), intent(in) :: pkgtype !< file type to load, such as DIS6, DISV6, NPF6
-    character(len=*), intent(in) :: component_type !< component type, such as GWF or GWT
-    character(len=*), intent(in) :: subcomponent_type !< subcomponent type, such as DIS or NPF
-    character(len=*), intent(in) :: component_name !< component name, such as MYGWFMODEL
-    character(len=*), intent(in) :: subcomponent_name !< subcomponent name, such as MYWELLPACKAGE
+    type(ModflowInputType), intent(in) :: mf6_input !< ModflowInputType
     integer(I4B), intent(in) :: iout !< unit number for output
     integer(I4B) :: iblock !< consecutive block number as defined in definition file
-    type(ModflowInputType) :: mf6_input !< ModflowInputType
     character(len=LENMEMPATH) :: componentMemPath
     integer(I4B), dimension(:), contiguous, pointer :: mshape => null()
     character(len=LINELENGTH) :: filename !< input filename
     !
-    ! -- construct input object
-    mf6_input = getModflowInput(pkgtype, component_type, &
-                                subcomponent_type, component_name, &
-                                subcomponent_name)
-    !
     ! -- model shape memory path
     componentMemPath = create_mem_path(component=mf6_input%component_name, &
                                        context=idm_context)
@@ -79,14 +67,17 @@ subroutine idm_load(parser, pkgtype, &
     !
     ! -- process blocks
     do iblock = 1, size(mf6_input%block_dfns)
+      !
+      ! -- don't load dynamic input data
+      if (mf6_input%block_dfns(iblock)%blockname == 'PERIOD') exit
+      !
+      ! -- load the block
       call parse_block(parser, mf6_input, iblock, mshape, filename, iout, .false.)
       !
-      ! -- set model shape if discretization dimensions have been read
-      if (mf6_input%block_dfns(iblock)%blockname == 'DIMENSIONS' .and. &
-          pkgtype(1:3) == 'DIS') then
-        call set_model_shape(mf6_input%pkgtype, componentMemPath, &
-                             mf6_input%mempath, mshape)
-      end if
+      ! --
+      call block_post_process(mf6_input, mf6_input%block_dfns(iblock)%blockname, &
+                              mshape, filename)
+      !
     end do
     !
     ! -- close logging statement
@@ -94,6 +85,41 @@ subroutine idm_load(parser, pkgtype, &
                        mf6_input%subcomponent_name, iout)
   end subroutine idm_load
 
+  subroutine block_post_process(mf6_input, blockname, mshape, filename)
+    use SourceCommonModule, only: set_model_shape, mem_allocate_naux
+    type(ModflowInputType), intent(in) :: mf6_input !< ModflowInputType
+    character(len=*), intent(in) :: blockname
+    integer(I4B), dimension(:), contiguous, pointer, intent(inout) :: mshape
+    character(len=*), intent(in) :: filename
+    type(InputParamDefinitionType), pointer :: idt
+    integer(I4B) :: iparam
+    !
+    select case (blockname)
+    case ('OPTIONS')
+      ! -- allocate naux and set to 0 if not allocated
+      do iparam = 1, size(mf6_input%param_dfns)
+        idt => mf6_input%param_dfns(iparam)
+        !
+        if (idt%blockname == 'OPTIONS' .and. &
+            idt%tagname == 'AUXILIARY') then
+          call mem_allocate_naux(mf6_input%mempath)
+          exit
+        end if
+      end do
+    case ('DIMENSIONS')
+      ! -- set model shape if discretization dimensions have been read
+      if (mf6_input%pkgtype(1:3) == 'DIS') then
+        call set_model_shape(mf6_input%pkgtype, filename, &
+                             mf6_input%component_mempath, &
+                             mf6_input%mempath, mshape)
+      end if
+    case default
+    end select
+    !
+    ! -- return
+    return
+  end subroutine block_post_process
+
   !> @brief procedure to load a block
   !!
   !! Use parser to load information from a block into the __INPUT__
@@ -218,7 +244,8 @@ subroutine parse_iofile_tag(parser, mf6_input, iblock, mshape, tag, found, &
                                       mf6_input%subcomponent_type, &
                                       mf6_input%block_dfns(iblock)%blockname, &
                                       words(4), filename)
-          call load_string_type(parser, idt, mf6_input%mempath, iout)
+          !
+          call load_io_tag(parser, idt, mf6_input%mempath, words(3), iout)
           !
           ! -- io tag loaded
           found = .true.
@@ -293,7 +320,11 @@ recursive subroutine parse_tag(parser, mf6_input, iblock, mshape, filename, &
         call parser%DevOpt()
       end if
     case ('STRING')
-      call load_string_type(parser, idt, mf6_input%mempath, iout)
+      if (idt%shape == 'NAUX') then
+        call load_auxvar_names(parser, idt, mf6_input%mempath, iout)
+      else
+        call load_string_type(parser, idt, mf6_input%mempath, iout)
+      end if
     case ('INTEGER')
       call load_integer_type(parser, idt, mf6_input%mempath, iout)
     case ('INTEGER1D')
@@ -318,7 +349,7 @@ recursive subroutine parse_tag(parser, mf6_input, iblock, mshape, filename, &
     !
     ! -- continue line if in same record
     if (idt%in_record) then
-
+      !
       ! recursively call parse tag again to read rest of line
       call parse_tag(parser, mf6_input, iblock, mshape, filename, iout, .true.)
     end if
@@ -327,6 +358,37 @@ recursive subroutine parse_tag(parser, mf6_input, iblock, mshape, filename, &
     return
   end subroutine parse_tag
 
+  function block_index_dfn(mf6_input, iblock, iout) result(idt)
+    type(ModflowInputType), intent(in) :: mf6_input !< ModflowInputType
+    integer(I4B), intent(in) :: iblock !< consecutive block number as defined in definition file
+    integer(I4B), intent(in) :: iout !< unit number for output
+    type(InputParamDefinitionType) :: idt !< input data type object describing this record
+    character(len=LENVARNAME) :: varname
+    integer(I4B) :: ilen
+    character(len=3) :: block_suffix = 'NUM'
+    !
+    ! -- assign first column as the block number
+    ilen = len_trim(mf6_input%block_dfns(iblock)%blockname)
+    !
+    if (ilen > (LENVARNAME - len(block_suffix))) then
+      varname = &
+        mf6_input%block_dfns(iblock)% &
+        blockname(1:(LENVARNAME - len(block_suffix)))//block_suffix
+    else
+      varname = trim(mf6_input%block_dfns(iblock)%blockname)//block_suffix
+    end if
+    !
+    idt%component_type = trim(mf6_input%component_type)
+    idt%subcomponent_type = trim(mf6_input%subcomponent_type)
+    idt%blockname = trim(mf6_input%block_dfns(iblock)%blockname)
+    idt%tagname = varname
+    idt%mf6varname = varname
+    idt%datatype = 'INTEGER'
+    !
+    ! -- return
+    return
+  end function block_index_dfn
+
   !> @brief parse a structured array record into memory manager
   !!
   !! A structarray is similar to a numpy recarray.  It it used to
@@ -346,16 +408,16 @@ subroutine parse_structarray_block(parser, mf6_input, iblock, mshape, &
     character(len=*), intent(in) :: filename !< input filename
     integer(I4B), intent(in) :: iout !< unit number for output
     type(InputParamDefinitionType), pointer :: idt !< input data type object describing this record
-    integer(I4B) :: blocknum, iwords, ilen
+    type(InputParamDefinitionType), target :: blockvar_idt
+    integer(I4B) :: blocknum, iwords
     integer(I4B), pointer :: nrow => null()
+    integer(I4B) :: nrows, nrowsread
     integer(I4B) :: icol
     integer(I4B) :: ncol
     integer(I4B) :: nwords
     character(len=16), dimension(:), allocatable :: words
     type(StructArrayType), pointer :: struct_array
     character(len=:), allocatable :: parse_str
-    character(len=100) :: varname
-    character(len=3) :: block_suffix = 'num'
     !
     ! -- set input definition for this block
     idt => get_aggregate_definition_type(mf6_input%aggregate_dfns, &
@@ -381,11 +443,15 @@ subroutine parse_structarray_block(parser, mf6_input, iblock, mshape, &
     ! -- use shape to set the max num of rows
     if (idt%shape /= '') then
       call mem_setptr(nrow, idt%shape, mf6_input%mempath)
+      nrows = nrow
+    else
+      nrows = 0
     end if
     !
     ! -- create a structured array
-    struct_array => constructStructArray(ncol, nrow, blocknum)
-    nullify (nrow)
+    struct_array => constructStructArray(mf6_input, ncol, nrows, blocknum, &
+                                         mf6_input%mempath, &
+                                         mf6_input%component_mempath)
     !
     ! -- create structarray vectors for each column
     do icol = 1, ncol
@@ -394,27 +460,16 @@ subroutine parse_structarray_block(parser, mf6_input, iblock, mshape, &
       if (blocknum > 0) then
         if (icol == 1) then
           !
-          ! -- assign first column as the block number
-          ilen = len_trim(mf6_input%block_dfns(iblock)%blockname)
-          !
-          if (ilen > (LENVARNAME - len(block_suffix))) then
-            varname = &
-              mf6_input%block_dfns(iblock)% &
-              blockname(1:(LENVARNAME - len(block_suffix)))//block_suffix
-          else
-            varname = trim(mf6_input%block_dfns(iblock)%blockname)//block_suffix
-          end if
+          blockvar_idt = block_index_dfn(mf6_input, iblock, iout)
+          idt => blockvar_idt
           !
-          call struct_array%mem_create_vector(icol, 'INTEGER', &
-                                              varname, varname, &
-                                              mf6_input%mempath, '', &
-                                              .false.)
+          call struct_array%mem_create_vector(icol, idt)
           !
           ! -- continue as this column managed by internally SA object
           cycle
         end if
         !
-        ! -- set indexex (where first column is blocknum)
+        ! -- set indexes (where first column is blocknum)
         iwords = icol
       else
         !
@@ -430,13 +485,11 @@ subroutine parse_structarray_block(parser, mf6_input, iblock, mshape, &
                                        words(iwords), filename)
       !
       ! -- allocate variable in memory manager
-      call struct_array%mem_create_vector(icol, idt%datatype, idt%mf6varname, &
-                                          idt%tagname, mf6_input%mempath, &
-                                          idt%shape, idt%preserve_case)
+      call struct_array%mem_create_vector(icol, idt)
     end do
     !
     ! -- read the structured array
-    call struct_array%read_from_parser(parser, iout)
+    nrowsread = struct_array%read_from_parser(parser, .false., iout)
     !
     ! -- destroy the structured array reader
     call destructStructArray(struct_array)
@@ -475,6 +528,76 @@ subroutine load_string_type(parser, idt, memoryPath, iout)
     return
   end subroutine load_string_type
 
+  !> @brief load type string
+  !<
+  subroutine load_io_tag(parser, idt, memoryPath, which, iout)
+    use MemoryManagerModule, only: mem_allocate, mem_reallocate, &
+                                   mem_setptr, get_isize
+    use CharacterStringModule, only: CharacterStringType
+    type(BlockParserType), intent(inout) :: parser !< block parser
+    type(InputParamDefinitionType), intent(in) :: idt !< input data type object describing this record
+    character(len=*), intent(in) :: memoryPath !< memorypath to put loaded information
+    character(len=*), intent(in) :: which
+    integer(I4B), intent(in) :: iout !< unit number for output
+    character(len=LINELENGTH) :: cstr
+    type(CharacterStringType), dimension(:), pointer, contiguous :: charstr1d
+    integer(I4B) :: ilen, isize, idx
+    ilen = LINELENGTH
+    if (which == 'FILEIN') then
+      call get_isize(idt%mf6varname, memoryPath, isize)
+      if (isize < 0) then
+        call mem_allocate(charstr1d, ilen, 1, idt%mf6varname, memoryPath)
+        idx = 1
+      else
+        call mem_setptr(charstr1d, idt%mf6varname, memoryPath)
+        call mem_reallocate(charstr1d, ilen, isize + 1, idt%mf6varname, &
+                            memoryPath)
+        idx = isize + 1
+      end if
+      call parser%GetString(cstr, (.not. idt%preserve_case))
+      charstr1d(idx) = cstr
+    else if (which == 'FILEOUT') then
+      call load_string_type(parser, idt, memoryPath, iout)
+    end if
+    return
+  end subroutine load_io_tag
+
+  !> @brief load aux variable names
+  !!
+  !<
+  subroutine load_auxvar_names(parser, idt, memoryPath, iout)
+    use ConstantsModule, only: LENAUXNAME, LINELENGTH, LENPACKAGENAME
+    use InputOutputModule, only: urdaux
+    use CharacterStringModule, only: CharacterStringType
+    type(BlockParserType), intent(inout) :: parser !< block parser
+    type(InputParamDefinitionType), intent(in) :: idt !< input data type object describing this record
+    character(len=*), intent(in) :: memoryPath !< memorypath to put loaded information
+    integer(I4B), intent(in) :: iout !< unit number for output
+    character(len=:), allocatable :: line
+    character(len=LENAUXNAME), dimension(:), allocatable :: caux
+    integer(I4B) :: lloc
+    integer(I4B) :: istart
+    integer(I4B) :: istop
+    integer(I4B) :: i
+    character(len=LENPACKAGENAME) :: text = ''
+    integer(I4B), pointer :: intvar
+    type(CharacterStringType), dimension(:), &
+      pointer, contiguous :: acharstr1d !< variable for allocation
+    call mem_allocate(intvar, idt%shape, memoryPath)
+    intvar = 0
+    call parser%GetRemainingLine(line)
+    lloc = 1
+    call urdaux(intvar, parser%iuactive, iout, lloc, &
+                istart, istop, caux, line, text)
+    call mem_allocate(acharstr1d, LENAUXNAME, intvar, idt%mf6varname, memoryPath)
+    do i = 1, intvar
+      acharstr1d(i) = caux(i)
+    end do
+    deallocate (line)
+    deallocate (caux)
+    return
+  end subroutine load_auxvar_names
+
   !> @brief load type integer
   !<
   subroutine load_integer_type(parser, idt, memoryPath, iout)
@@ -492,6 +615,7 @@ end subroutine load_integer_type
   !> @brief load type 1d integer
   !<
   subroutine load_integer1d_type(parser, idt, memoryPath, mshape, iout)
+    use SourceCommonModule, only: get_shape_from_string
     type(BlockParserType), intent(inout) :: parser !< block parser
     type(InputParamDefinitionType), intent(in) :: idt !< input data type object describing this record
     character(len=*), intent(in) :: memoryPath !< memorypath to put loaded information
@@ -539,6 +663,7 @@ end subroutine load_integer1d_type
   !> @brief load type 2d integer
   !<
   subroutine load_integer2d_type(parser, idt, memoryPath, mshape, iout)
+    use SourceCommonModule, only: get_shape_from_string
     type(BlockParserType), intent(inout) :: parser !< block parser
     type(InputParamDefinitionType), intent(in) :: idt !< input data type object describing this record
     character(len=*), intent(in) :: memoryPath !< memorypath to put loaded information
@@ -582,6 +707,7 @@ end subroutine load_integer2d_type
   !> @brief load type 3d integer
   !<
   subroutine load_integer3d_type(parser, idt, memoryPath, mshape, iout)
+    use SourceCommonModule, only: get_shape_from_string
     type(BlockParserType), intent(inout) :: parser !< block parser
     type(InputParamDefinitionType), intent(in) :: idt !< input data type object describing this record
     character(len=*), intent(in) :: memoryPath !< memorypath to put loaded information
@@ -645,6 +771,7 @@ end subroutine load_double_type
   !> @brief load type 1d double
   !<
   subroutine load_double1d_type(parser, idt, memoryPath, mshape, iout)
+    use SourceCommonModule, only: get_shape_from_string
     type(BlockParserType), intent(inout) :: parser !< block parser
     type(InputParamDefinitionType), intent(in) :: idt !< input data type object describing this record
     character(len=*), intent(in) :: memoryPath !< memorypath to put loaded information
@@ -691,6 +818,7 @@ end subroutine load_double1d_type
   !> @brief load type 2d double
   !<
   subroutine load_double2d_type(parser, idt, memoryPath, mshape, iout)
+    use SourceCommonModule, only: get_shape_from_string
     type(BlockParserType), intent(inout) :: parser !< block parser
     type(InputParamDefinitionType), intent(in) :: idt !< input data type object describing this record
     character(len=*), intent(in) :: memoryPath !< memorypath to put loaded information
@@ -734,6 +862,7 @@ end subroutine load_double2d_type
   !> @brief load type 3d double
   !<
   subroutine load_double3d_type(parser, idt, memoryPath, mshape, iout)
+    use SourceCommonModule, only: get_shape_from_string
     type(BlockParserType), intent(inout) :: parser !< block parser
     type(InputParamDefinitionType), intent(in) :: idt !< input data type object describing this record
     character(len=*), intent(in) :: memoryPath !< memorypath to put loaded information
@@ -780,45 +909,6 @@ subroutine load_double3d_type(parser, idt, memoryPath, mshape, iout)
     return
   end subroutine load_double3d_type
 
-  !> @brief routine for setting the model shape
-  !!
-  !! The model shape must be set in the memory manager because
-  !! individual packages need to know the shape of the arrays
-  !! to read.
-  !!
-  !<
-  subroutine set_model_shape(ftype, model_mempath, dis_mempath, model_shape)
-    use MemoryTypeModule, only: MemoryType
-    use MemoryManagerModule, only: get_from_memorylist
-    character(len=*), intent(in) :: ftype
-    character(len=*), intent(in) :: model_mempath
-    character(len=*), intent(in) :: dis_mempath
-    integer(I4B), dimension(:), pointer, contiguous, intent(inout) :: model_shape
-    integer(I4B), pointer :: ndim1
-    integer(I4B), pointer :: ndim2
-    integer(I4B), pointer :: ndim3
-
-    select case (ftype)
-    case ('DIS6')
-      call mem_allocate(model_shape, 3, 'MODEL_SHAPE', model_mempath)
-      call mem_setptr(ndim1, 'NLAY', dis_mempath)
-      call mem_setptr(ndim2, 'NROW', dis_mempath)
-      call mem_setptr(ndim3, 'NCOL', dis_mempath)
-      model_shape = [ndim1, ndim2, ndim3]
-    case ('DISV6')
-      call mem_allocate(model_shape, 2, 'MODEL_SHAPE', model_mempath)
-      call mem_setptr(ndim1, 'NLAY', dis_mempath)
-      call mem_setptr(ndim2, 'NCPL', dis_mempath)
-      model_shape = [ndim1, ndim2]
-    case ('DISU6')
-      call mem_allocate(model_shape, 1, 'MODEL_SHAPE', model_mempath)
-      call mem_setptr(ndim1, 'NODES', dis_mempath)
-      model_shape = [ndim1]
-    end select
-
-    return
-  end subroutine set_model_shape
-
   subroutine get_layered_shape(mshape, nlay, layer_shape)
     integer(I4B), dimension(:), intent(in) :: mshape
     integer(I4B), intent(out) :: nlay
@@ -845,27 +935,4 @@ subroutine get_layered_shape(mshape, nlay, layer_shape)
 
   end subroutine get_layered_shape
 
-  subroutine get_shape_from_string(shape_string, array_shape, memoryPath)
-    character(len=*), intent(in) :: shape_string
-    integer(I4B), dimension(:), allocatable, intent(inout) :: array_shape
-    character(len=*), intent(in) :: memoryPath !< memorypath to put loaded information
-    integer(I4B) :: ndim
-    integer(I4B) :: i
-    integer(I4B), pointer :: int_ptr
-    character(len=16), dimension(:), allocatable :: array_shape_string
-    character(len=:), allocatable :: shape_string_copy
-
-    ! parse the string into multiple words
-    shape_string_copy = trim(shape_string)//' '
-    call ParseLine(shape_string_copy, ndim, array_shape_string)
-    allocate (array_shape(ndim))
-
-    ! find shape in memory manager and put into array_shape
-    do i = 1, ndim
-      call mem_setptr(int_ptr, array_shape_string(i), memoryPath)
-      array_shape(i) = int_ptr
-    end do
-
-  end subroutine get_shape_from_string
-
 end module LoadMf6FileModule
diff --git a/src/Utilities/Idm/mf6blockfile/StressGridInput.f90 b/src/Utilities/Idm/mf6blockfile/StressGridInput.f90
new file mode 100644
index 00000000000..1cade321848
--- /dev/null
+++ b/src/Utilities/Idm/mf6blockfile/StressGridInput.f90
@@ -0,0 +1,513 @@
+!> @brief This module contains the StressGridInputModule
+!!
+!! This module contains the routines for reading period block
+!! array based input.
+!!
+!<
+module StressGridInputModule
+
+  use KindModule, only: I4B, DP, LGP
+  use ConstantsModule, only: DZERO, IZERO, LINELENGTH, LENMEMPATH, LENVARNAME, &
+                             LENTIMESERIESNAME, LENAUXNAME
+  use SimVariablesModule, only: errmsg
+  use SimModule, only: store_error, store_error_filename
+  use InputDefinitionModule, only: InputParamDefinitionType
+  use MemoryManagerModule, only: mem_allocate, mem_reallocate, mem_setptr
+  use CharacterStringModule, only: CharacterStringType
+  use BlockParserModule, only: BlockParserType
+  use ModflowInputModule, only: ModflowInputType, getModflowInput
+  use BoundInputContextModule, only: BoundInputContextType
+  use TimeArraySeriesManagerModule, only: TimeArraySeriesManagerType, &
+                                          tasmanager_cr
+  use AsciiInputLoadTypeModule, only: AsciiDynamicPkgLoadBaseType
+
+  implicit none
+  private
+  public :: StressGridInputType
+
+  !> @brief Pointer type for read state variable
+  !<
+  type ReadStateVar
+    integer, pointer :: invar
+  end type ReadStateVar
+
+  !> @brief Ascii grid based dynamic loader type
+  !<
+  type, extends(AsciiDynamicPkgLoadBaseType) :: StressGridInputType
+    integer(I4B) :: tas_active !< Are TAS6 inputs defined
+    integer(I4B) :: nparam !< number of dynamic parameters other than AUX
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: aux_tasnames => null() !< array of AUXVAR TAS names
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: param_tasnames => null() !< array of dynamic param TAS names
+    character(len=LENVARNAME), dimension(:), &
+      allocatable :: param_names !< dynamic param names
+    type(ReadStateVar), dimension(:), allocatable :: param_reads !< read states for current load
+    integer(I4B), dimension(:), allocatable :: idt_idxs !< idt indexes corresponding to dfn param list
+    type(TimeArraySeriesManagerType), pointer :: tasmanager => null() !< TAS manager object
+    type(BoundInputContextType) :: bndctx !< boundary package input context
+  contains
+    procedure :: init => ingrid_init
+    procedure :: df => ingrid_df
+    procedure :: ad => ingrid_ad
+    procedure :: rp => ingrid_rp
+    procedure :: destroy => ingrid_destroy
+    procedure :: reset => ingrid_reset
+    procedure :: params_alloc => ingrid_params_alloc
+    procedure :: param_load => ingrid_param_load
+    procedure :: tas_arrays_alloc => ingrid_tas_arrays_alloc
+    procedure :: tas_links_create => ingrid_tas_links_create
+  end type StressGridInputType
+
+contains
+
+  subroutine ingrid_init(this, mf6_input, modelname, modelfname, &
+                         source, iperblock, iout)
+    use MemoryManagerModule, only: get_isize
+    class(StressGridInputType), intent(inout) :: this
+    type(ModflowInputType), intent(in) :: mf6_input
+    character(len=*), intent(in) :: modelname
+    character(len=*), intent(in) :: modelfname
+    character(len=*), intent(in) :: source
+    integer(I4B), intent(in) :: iperblock
+    integer(I4B), intent(in) :: iout
+    type(CharacterStringType), dimension(:), pointer, &
+      contiguous :: tas_fnames
+    character(len=LINELENGTH) :: fname
+    integer(I4B) :: tas6_size, n
+    !
+    call this%DynamicPkgLoadType%init(mf6_input, modelname, modelfname, &
+                                      source, iperblock, iout)
+    ! -- initialize
+    this%tas_active = 0
+    this%nparam = 0
+    this%iout = iout
+    !
+    ! -- create tasmanager
+    allocate (this%tasmanager)
+    call tasmanager_cr(this%tasmanager, modelname=this%mf6_input%component_name, &
+                       iout=this%iout)
+    !
+    ! -- determine if TAS6 files were provided in OPTIONS block
+    call get_isize('TAS6_FILENAME', this%mf6_input%mempath, tas6_size)
+    !
+    if (tas6_size > 0) then
+      !
+      this%tas_active = 1
+      !
+      call mem_setptr(tas_fnames, 'TAS6_FILENAME', this%mf6_input%mempath)
+      !
+      ! -- add files to tasmanager
+      do n = 1, size(tas_fnames)
+        fname = tas_fnames(n)
+        call this%tasmanager%add_tasfile(fname)
+      end do
+      !
+    end if
+    !
+    ! -- initialize input context memory
+    call this%bndctx%init(mf6_input, .true.)
+    !
+    ! -- allocate dfn params
+    call this%params_alloc()
+    !
+    ! -- allocate memory for storing TAS strings
+    call this%tas_arrays_alloc()
+    !
+    ! -- return
+    return
+  end subroutine ingrid_init
+
+  subroutine ingrid_df(this)
+    ! -- modules
+    class(StressGridInputType), intent(inout) :: this !< Mf6FileGridInputType
+    !
+    call this%tasmanager%tasmanager_df()
+    !
+    ! -- return
+    return
+  end subroutine ingrid_df
+
+  subroutine ingrid_ad(this)
+    ! -- modules
+    class(StressGridInputType), intent(inout) :: this !< Mf6FileGridInputType
+    !
+    call this%tasmanager%ad()
+    !
+    ! -- return
+    return
+  end subroutine ingrid_ad
+
+  subroutine ingrid_rp(this, parser)
+    ! -- modules
+    use MemoryManagerModule, only: mem_setptr
+    use BlockParserModule, only: BlockParserType
+    use InputDefinitionModule, only: InputParamDefinitionType
+    use DefinitionSelectModule, only: get_param_definition_type
+    use ArrayHandlersModule, only: ifind
+    use SourceCommonModule, only: ifind_charstr
+    use IdmLoggerModule, only: idm_log_header, idm_log_close, idm_log_var
+    class(StressGridInputType), intent(inout) :: this !< Mf6FileGridInputType
+    type(BlockParserType), pointer, intent(inout) :: parser
+    ! -- locals
+    logical(LGP) :: endOfBlock
+    character(len=LINELENGTH) :: keyword, param_tag
+    type(InputParamDefinitionType), pointer :: idt
+    integer(I4B) :: iaux, iparam
+    character(len=LENTIMESERIESNAME) :: tas_name
+    !
+    ! -- reset for this period
+    call this%reset()
+    !
+    ! -- log lst file header
+    call idm_log_header(this%mf6_input%component_name, &
+                        this%mf6_input%subcomponent_name, this%iout)
+    !
+    ! -- read array block
+    do
+      ! -- initialize
+      iaux = 0
+      !
+      ! -- read next line
+      call parser%GetNextLine(endOfBlock)
+      if (endOfBlock) exit
+      !
+      ! -- read param_tag
+      call parser%GetStringCaps(param_tag)
+      !
+      ! -- is param tag an auxvar?
+      iaux = ifind_charstr(this%bndctx%auxname_cst, param_tag)
+      !
+      ! -- any auvxar corresponds to the definition tag 'AUX'
+      if (iaux > 0) param_tag = 'AUX'
+      !
+      ! -- set input definition
+      idt => get_param_definition_type(this%mf6_input%param_dfns, &
+                                       this%mf6_input%component_type, &
+                                       this%mf6_input%subcomponent_type, &
+                                       'PERIOD', param_tag, this%sourcename)
+      !
+      ! -- look for TAS keyword if tas is active
+      if (this%tas_active /= 0) then
+        call parser%GetStringCaps(keyword)
+        !
+        if (keyword == 'TIMEARRAYSERIES') then
+          call parser%GetStringCaps(tas_name)
+          !
+          if (param_tag == 'AUX') then
+            this%aux_tasnames(iaux) = tas_name
+          else
+            iparam = ifind(this%param_names, param_tag)
+            this%param_tasnames(iparam) = tas_name
+            this%param_reads(iparam)%invar = 2
+          end if
+          !
+          ! -- log variable
+          call idm_log_var(param_tag, this%mf6_input%mempath, this%iout, .true.)
+          !
+          ! -- cycle to next input param
+          cycle
+        end if
+        !
+      end if
+      !
+      ! -- read and load the parameter
+      call this%param_load(parser, idt%datatype, idt%mf6varname, idt%tagname, &
+                           this%mf6_input%mempath, iaux)
+      !
+    end do
+    !
+    !
+    if (this%tas_active /= 0) then
+      call this%tas_links_create(parser%iuactive)
+    end if
+    !
+    ! -- log lst file header
+    call idm_log_close(this%mf6_input%component_name, &
+                       this%mf6_input%subcomponent_name, this%iout)
+    !
+    ! -- return
+    return
+  end subroutine ingrid_rp
+
+  subroutine ingrid_destroy(this)
+    ! -- modules
+    class(StressGridInputType), intent(inout) :: this !< Mf6FileGridInputType
+    !
+    deallocate (this%tasmanager)
+    !
+    ! -- return
+    return
+  end subroutine ingrid_destroy
+
+  subroutine ingrid_reset(this)
+    ! -- modules
+    use MemoryManagerModule, only: mem_deallocate, mem_setptr, get_isize
+    use InputDefinitionModule, only: InputParamDefinitionType
+    use DefinitionSelectModule, only: get_param_definition_type
+    class(StressGridInputType), intent(inout) :: this !< StressGridInputType
+    integer(I4B) :: n, m
+    !
+    if (this%tas_active /= 0) then
+      !
+      ! -- reset tasmanager
+      call this%tasmanager%reset(this%mf6_input%subcomponent_name)
+      !
+      ! -- reinitialize tas name arrays
+      call this%bndctx%param_init('CHARSTR1D', 'AUXTASNAME', &
+                                  this%mf6_input%mempath, this%sourcename)
+      call this%bndctx%param_init('CHARSTR1D', 'PARAMTASNAME', &
+                                  this%mf6_input%mempath, this%sourcename)
+    end if
+    !
+    do n = 1, this%nparam
+      if (this%param_reads(n)%invar /= 0) then
+        !
+        ! -- reset read state
+        this%param_reads(n)%invar = 0
+        !
+      end if
+    end do
+    !
+    ! -- explicitly reset auxvar array each period
+    do m = 1, this%bndctx%ncpl
+      do n = 1, this%bndctx%naux
+        this%bndctx%auxvar(n, m) = DZERO
+      end do
+    end do
+    !
+    ! -- return
+    return
+  end subroutine ingrid_reset
+
+  subroutine ingrid_params_alloc(this)
+    ! -- modules
+    use MemoryManagerModule, only: mem_allocate
+    use InputDefinitionModule, only: InputParamDefinitionType
+    use DefinitionSelectModule, only: get_param_definition_type
+    use ArrayHandlersModule, only: expandarray
+    ! -- dummy
+    class(StressGridInputType), intent(inout) :: this !< StressGridInputType
+    type(InputParamDefinitionType), pointer :: idt
+    character(len=LENVARNAME), dimension(:), allocatable :: read_state_varnames
+    integer(I4B), pointer :: intvar
+    integer(I4B) :: iparam
+    !
+    ! -- allocate period dfn params
+    call this%bndctx%bound_params_allocate(this%sourcename)
+    !
+    ! -- allocate dfn input params
+    do iparam = 1, size(this%mf6_input%param_dfns)
+      !
+      ! -- assign param definition pointer
+      idt => this%mf6_input%param_dfns(iparam)
+      !
+      if (idt%blockname == 'PERIOD') then
+        !
+        ! -- store parameter info
+        if (idt%tagname /= 'AUX') then
+          this%nparam = this%nparam + 1
+          !
+          ! -- reallocate param info arrays
+          call expandarray(this%param_names)
+          call expandarray(this%idt_idxs)
+          call expandarray(read_state_varnames)
+          !
+          ! -- internal mf6 param name
+          this%param_names(this%nparam) = idt%mf6varname
+          ! -- idt list index of param
+          this%idt_idxs(this%nparam) = iparam
+          ! -- allocate and store name of read state variable
+          read_state_varnames(this%nparam) = &
+            this%bndctx%allocate_read_state_var(idt%mf6varname)
+          !
+        end if
+        !
+      end if
+    end do
+    !
+    ! -- allocate and set param_reads pointer array
+    allocate (this%param_reads(this%nparam))
+    !
+    ! store read state variable pointers
+    do iparam = 1, this%nparam
+      call mem_setptr(intvar, read_state_varnames(iparam), this%mf6_input%mempath)
+      this%param_reads(iparam)%invar => intvar
+    end do
+    !
+    ! -- cleanup
+    deallocate (read_state_varnames)
+    !
+    ! -- return
+    return
+  end subroutine ingrid_params_alloc
+
+  subroutine ingrid_param_load(this, parser, datatype, varname, &
+                               tagname, mempath, iaux)
+    ! -- modules
+    use MemoryManagerModule, only: mem_setptr
+    use ArrayHandlersModule, only: ifind
+    use InputDefinitionModule, only: InputParamDefinitionType
+    use DefinitionSelectModule, only: get_param_definition_type
+    use Double1dReaderModule, only: read_dbl1d
+    use Double2dReaderModule, only: read_dbl2d
+    use Integer1dReaderModule, only: read_int1d
+    use IdmLoggerModule, only: idm_log_var
+    ! -- dummy
+    class(StressGridInputType), intent(inout) :: this !< StressGridInputType
+    type(BlockParserType), intent(in) :: parser
+    character(len=*), intent(in) :: datatype
+    character(len=*), intent(in) :: varname
+    character(len=*), intent(in) :: tagname
+    character(len=*), intent(in) :: mempath
+    integer(I4B), intent(in) :: iaux
+    ! -- locals
+    integer(I4B), dimension(:), pointer, contiguous :: int1d
+    real(DP), dimension(:), pointer, contiguous :: dbl1d
+    real(DP), dimension(:, :), pointer, contiguous :: dbl2d
+    integer(I4B) :: iparam
+    !
+    select case (datatype)
+    case ('INTEGER1D')
+      !
+      call mem_setptr(int1d, varname, mempath)
+      call read_int1d(parser, int1d, varname)
+      call idm_log_var(int1d, tagname, mempath, this%iout)
+      !
+    case ('DOUBLE1D')
+      !
+      call mem_setptr(dbl1d, varname, mempath)
+      call read_dbl1d(parser, dbl1d, varname)
+      call idm_log_var(dbl1d, tagname, mempath, this%iout)
+      !
+    case ('DOUBLE2D')
+      !
+      call mem_setptr(dbl2d, varname, mempath)
+      call read_dbl1d(parser, dbl2d(iaux, :), varname)
+      call idm_log_var(dbl2d, tagname, mempath, this%iout)
+      !
+    case default
+      !
+      call store_error('Programming error. (IDM) unsupported memload &
+                       &data type for param='//trim(tagname))
+      call store_error_filename(this%sourcename)
+      !
+    end select
+    !
+    iparam = ifind(this%param_names, varname)
+    !
+    ! -- if param is tracked set read state
+    if (iparam > 0) then
+      this%param_reads(iparam)%invar = 1
+    end if
+    !
+    ! -- return
+    return
+  end subroutine ingrid_param_load
+
+  subroutine ingrid_tas_arrays_alloc(this)
+    ! -- modules
+    use MemoryManagerModule, only: mem_allocate
+    class(StressGridInputType), intent(inout) :: this !< StressGridInputType
+    !
+    ! -- count params other than AUX
+    if (this%tas_active /= 0) then
+      !
+      call mem_allocate(this%aux_tasnames, LENTIMESERIESNAME, this%bndctx%naux, &
+                        'AUXTASNAME', this%mf6_input%mempath)
+      call mem_allocate(this%param_tasnames, LENTIMESERIESNAME, this%nparam, &
+                        'PARAMTASNAME', this%mf6_input%mempath)
+      !
+      call this%bndctx%param_init('CHARSTR1D', 'AUXTASNAME', &
+                                  this%mf6_input%mempath, &
+                                  this%sourcename)
+      call this%bndctx%param_init('CHARSTR1D', 'PARAMTASNAME', &
+                                  this%mf6_input%mempath, &
+                                  this%sourcename)
+      !
+    else
+      !
+      call mem_allocate(this%aux_tasnames, LENTIMESERIESNAME, 0, &
+                        'AUXTASNAME', this%mf6_input%mempath)
+      call mem_allocate(this%param_tasnames, LENTIMESERIESNAME, 0, &
+                        'PARAMTASNAME', this%mf6_input%mempath)
+      !
+    end if
+    !
+    ! -- return
+    return
+  end subroutine ingrid_tas_arrays_alloc
+
+  ! FLUX and SFAC are handled in model context
+  subroutine ingrid_tas_links_create(this, inunit)
+    ! -- modules
+    use InputDefinitionModule, only: InputParamDefinitionType
+    ! -- dummy
+    class(StressGridInputType), intent(inout) :: this !< StressGridInputType
+    integer(I4B), intent(in) :: inunit
+    ! -- locals
+    type(InputParamDefinitionType), pointer :: idt
+    ! -- non-contiguous beacuse a slice of bound is passed
+    real(DP), dimension(:), pointer :: auxArrayPtr, bndArrayPtr
+    real(DP), dimension(:), pointer, contiguous :: bound
+    integer(I4B), dimension(:), pointer, contiguous :: nodelist
+    character(len=LENTIMESERIESNAME) :: tas_name
+    character(len=LENAUXNAME) :: aux_name
+    logical :: convertFlux
+    integer(I4B) :: n
+    !
+    ! -- initialize
+    nullify (auxArrayPtr)
+    nullify (bndArrayPtr)
+    nullify (nodelist)
+    convertflux = .false.
+    !
+    ! Create AUX Time Array Series links
+    do n = 1, this%bndctx%naux
+      tas_name = this%aux_tasnames(n)
+      !
+      if (tas_name /= '') then
+        !
+        ! -- set auxvar pointer
+        auxArrayPtr => this%bndctx%auxvar(n, :)
+        !
+        aux_name = this%bndctx%auxname_cst(n)
+        !
+        call this%tasmanager%MakeTasLink(this%mf6_input%subcomponent_name, &
+                                         auxArrayPtr, this%bndctx%iprpak, &
+                                         tas_name, aux_name, convertFlux, &
+                                         nodelist, inunit)
+      end if
+      !
+    end do
+    !
+    ! Create BND Time Array Series links
+    do n = 1, this%nparam
+      !
+      ! -- assign param definition pointer
+      idt => this%mf6_input%param_dfns(this%idt_idxs(n))
+      !
+      if (idt%timeseries) then
+        !
+        if (this%param_reads(n)%invar == 2) then
+          tas_name = this%param_tasnames(n)
+          !
+          call mem_setptr(bound, idt%mf6varname, this%mf6_input%mempath)
+          !
+          ! -- set bound pointer
+          bndArrayPtr => bound(:)
+          !
+          call this%tasmanager%MakeTasLink(this%mf6_input%subcomponent_name, &
+                                           bndArrayPtr, this%bndctx%iprpak, &
+                                           tas_name, idt%mf6varname, &
+                                           convertFlux, nodelist, inunit)
+        end if
+      end if
+    end do
+
+    !
+    ! -- return
+    return
+  end subroutine ingrid_tas_links_create
+
+end module StressGridInputModule
diff --git a/src/Utilities/Idm/mf6blockfile/StressListInput.f90 b/src/Utilities/Idm/mf6blockfile/StressListInput.f90
new file mode 100644
index 00000000000..8528397ad27
--- /dev/null
+++ b/src/Utilities/Idm/mf6blockfile/StressListInput.f90
@@ -0,0 +1,439 @@
+!> @brief This module contains the StressListInputModule
+!!
+!! This module contains the routines for reading period block
+!! list based input.
+!!
+!<
+module StressListInputModule
+
+  use KindModule, only: I4B, DP, LGP
+  use ConstantsModule, only: DZERO, IZERO, LINELENGTH, LENMEMPATH, LENVARNAME, &
+                             LENTIMESERIESNAME, LENAUXNAME, LENBOUNDNAME
+  use SimVariablesModule, only: errmsg
+  use SimModule, only: store_error, count_errors, store_error_unit
+  use InputOutputModule, only: openfile, getunit
+  use InputDefinitionModule, only: InputParamDefinitionType
+  use MemoryManagerModule, only: mem_allocate, mem_reallocate, mem_setptr
+  use CharacterStringModule, only: CharacterStringType
+  use ModflowInputModule, only: ModflowInputType, getModflowInput
+  use TimeSeriesManagerModule, only: TimeSeriesManagerType, tsmanager_cr
+  use BoundInputContextModule, only: BoundInputContextType
+  use StructArrayModule, only: StructArrayType, constructStructArray, &
+                               destructStructArray
+  use AsciiInputLoadTypeModule, only: AsciiDynamicPkgLoadBaseType
+
+  implicit none
+  private
+  public :: StressListInputType
+
+  !> @brief Ascii list based dynamic loader type
+  !<
+  type, extends(AsciiDynamicPkgLoadBaseType) :: StressListInputType
+    integer(I4B) :: ts_active
+    integer(I4B) :: ibinary
+    integer(I4B) :: oc_inunit
+    integer(I4B) :: ncol
+    integer(I4B) :: iboundname
+    character(len=LENVARNAME), dimension(:), allocatable :: cols
+    type(TimeSeriesManagerType), pointer :: tsmanager => null()
+    type(StructArrayType), pointer :: structarray
+    type(BoundInputContextType) :: bndctx
+  contains
+    procedure :: init => inlist_init
+    procedure :: df => inlist_df
+    procedure :: ad => inlist_ad
+    procedure :: rp => inlist_rp
+    procedure :: destroy => inlist_destroy
+    procedure :: reset => inlist_reset
+    procedure :: ts_link => inlist_ts_link
+    procedure :: ts_update => inlist_ts_update
+    procedure :: create_structarray
+    procedure :: read_control_record
+  end type StressListInputType
+
+contains
+
+  subroutine inlist_init(this, mf6_input, modelname, modelfname, &
+                         source, iperblock, iout)
+    use MemoryManagerModule, only: get_isize
+    class(StressListInputType), intent(inout) :: this
+    type(ModflowInputType), intent(in) :: mf6_input
+    character(len=*), intent(in) :: modelname
+    character(len=*), intent(in) :: modelfname
+    character(len=*), intent(in) :: source
+    integer(I4B), intent(in) :: iperblock
+    integer(I4B), intent(in) :: iout
+    type(CharacterStringType), dimension(:), pointer, &
+      contiguous :: ts_fnames
+    character(len=LINELENGTH) :: fname
+    integer(I4B) :: ts6_size, n
+    !
+    call this%DynamicPkgLoadType%init(mf6_input, modelname, modelfname, &
+                                      source, iperblock, iout)
+    !
+    ! -- initialize
+    this%ts_active = 0
+    this%ibinary = 0
+    this%oc_inunit = 0
+    !
+    ! -- create tsmanager
+    allocate (this%tsmanager)
+    call tsmanager_cr(this%tsmanager, iout)
+    !
+    ! -- determine if TS6 files were provided in OPTIONS block
+    call get_isize('TS6_FILENAME', this%mf6_input%mempath, ts6_size)
+    !
+    if (ts6_size > 0) then
+      !
+      this%ts_active = 1
+      call mem_setptr(ts_fnames, 'TS6_FILENAME', this%mf6_input%mempath)
+      !
+      do n = 1, size(ts_fnames)
+        fname = ts_fnames(n)
+        call this%tsmanager%add_tsfile(fname, GetUnit())
+      end do
+      !
+    end if
+    !
+    ! -- initialize package input context
+    call this%bndctx%init(mf6_input, .false.)
+    !
+    ! -- set SA cols in scope for list input
+    call this%bndctx%filtered_cols(this%cols, this%ncol)
+    !
+    ! -- construct and set up the struct array object
+    call this%create_structarray()
+    !
+    ! -- finalize input context setup
+    call this%bndctx%enable()
+    !
+    ! -- return
+    return
+  end subroutine inlist_init
+
+  subroutine inlist_df(this)
+    ! -- modules
+    class(StressListInputType), intent(inout) :: this !< StressListInputType
+    !
+    ! -- define tsmanager
+    call this%tsmanager%tsmanager_df()
+    !
+    ! -- return
+    return
+  end subroutine inlist_df
+
+  subroutine inlist_ad(this)
+    ! -- modules
+    class(StressListInputType), intent(inout) :: this !< StressListInputType
+    !
+    ! -- advance tsmanager
+    call this%tsmanager%ad()
+    !
+    ! -- return
+    return
+  end subroutine inlist_ad
+
+  subroutine inlist_rp(this, parser)
+    ! -- modules
+    use BlockParserModule, only: BlockParserType
+    use StructVectorModule, only: StructVectorType
+    use IdmLoggerModule, only: idm_log_header, idm_log_close
+    ! -- dummy
+    class(StressListInputType), intent(inout) :: this
+    type(BlockParserType), pointer, intent(inout) :: parser
+    ! -- locals
+    logical(LGP) :: ts_active
+    !
+    call this%reset()
+    !
+    call this%read_control_record(parser)
+    !
+    ! -- log lst file header
+    call idm_log_header(this%mf6_input%component_name, &
+                        this%mf6_input%subcomponent_name, this%iout)
+    !
+    if (this%ibinary == 1) then
+      !
+      this%bndctx%nbound = &
+        this%structarray%read_from_binary(this%oc_inunit, this%iout)
+      !
+      call parser%terminateblock()
+      !
+      close (this%oc_inunit)
+      this%ibinary = 0
+      this%oc_inunit = 0
+      !
+    else
+      !
+      ts_active = (this%ts_active /= 0)
+      !
+      this%bndctx%nbound = &
+        this%structarray%read_from_parser(parser, &
+                                          ts_active, this%iout)
+    end if
+    !
+    ! update ts links
+    if (this%ts_active /= 0) then
+      call this%ts_update()
+    end if
+    !
+    ! -- close logging statement
+    call idm_log_close(this%mf6_input%component_name, &
+                       this%mf6_input%subcomponent_name, this%iout)
+    !
+    ! -- return
+    return
+  end subroutine inlist_rp
+
+  subroutine inlist_destroy(this)
+    ! -- modules
+    class(StressListInputType), intent(inout) :: this !< StressListInputType
+    !
+    deallocate (this%cols)
+    deallocate (this%tsmanager)
+    call destructStructArray(this%structarray)
+    call this%bndctx%destroy()
+    !
+    ! -- return
+    return
+  end subroutine inlist_destroy
+
+  subroutine inlist_reset(this)
+    ! -- modules
+    class(StressListInputType), intent(inout) :: this !< StressListInputType
+    !
+    ! -- reset tsmanager
+    call this%tsmanager%reset(this%mf6_input%subcomponent_name)
+    !
+    ! -- return
+    return
+  end subroutine inlist_reset
+
+  subroutine inlist_ts_link(this, structvector, ts_strloc)
+    ! -- modules
+    use TimeSeriesLinkModule, only: TimeSeriesLinkType
+    use TimeSeriesManagerModule, only: read_value_or_time_series
+    use StructVectorModule, only: StructVectorType, TSStringLocType
+    !use ArrayHandlersModule, only: ifind
+    ! -- dummy
+    class(StressListInputType), intent(inout) :: this
+    type(StructVectorType), pointer, intent(in) :: structvector
+    type(TSStringLocType), pointer, intent(in) :: ts_strloc
+    ! -- locals
+    real(DP), pointer :: bndElem => null()
+    type(TimeSeriesLinkType), pointer :: tsLinkBnd => null()
+    type(TimeSeriesLinkType), pointer :: tsLinkAux => null()
+    type(StructVectorType), pointer :: sv_bound
+    character(len=LENBOUNDNAME) :: boundname
+    !
+    select case (structvector%memtype)
+    case (2)
+      !
+      tsLinkBnd => NULL()
+      !
+      ! -- set bound element
+      bndElem => structvector%dbl1d(ts_strloc%row)
+      !
+      ! -- set link
+      call read_value_or_time_series(ts_strloc%token, ts_strloc%row, &
+                                     ts_strloc%structarray_col, bndElem, &
+                                     this%mf6_input%subcomponent_name, &
+                                     'BND', this%tsmanager, &
+                                     this%bndctx%iprpak, tsLinkBnd)
+      !
+      if (associated(tsLinkBnd)) then
+        !
+        ! -- set variable name
+        tsLinkBnd%Text = structvector%idt%mf6varname
+        !
+        ! -- set boundname if provided
+        if (this%bndctx%inamedbound > 0) then
+          sv_bound => this%structarray%get(this%iboundname)
+          boundname = sv_bound%charstr1d(ts_strloc%row)
+          tsLinkBnd%BndName = boundname
+        end if
+
+        ! Flux is handled from model context
+
+      end if
+      !
+    case (6)
+      !
+      tsLinkAux => NULL()
+      !
+      ! -- set bound element
+      bndElem => structvector%dbl2d(ts_strloc%col, ts_strloc%row)
+      !
+      ! -- set link
+      call read_value_or_time_series(ts_strloc%token, ts_strloc%row, &
+                                     ts_strloc%structarray_col, bndElem, &
+                                     this%mf6_input%subcomponent_name, &
+                                     'AUX', this%tsmanager, &
+                                     this%bndctx%iprpak, tsLinkAux)
+
+      if (associated(tsLinkAux)) then
+        !
+        ! -- set variable name
+        tsLinkAux%Text = this%bndctx%auxname_cst(ts_strloc%col)
+        !
+        ! -- set boundname if provided
+        if (this%bndctx%inamedbound > 0) then
+          sv_bound => this%structarray%get(this%iboundname)
+          boundname = sv_bound%charstr1d(ts_strloc%row)
+          tsLinkAux%BndName = boundname
+        end if
+        !
+      end if
+      !
+    case default
+    end select
+    !
+    ! -- return
+    return
+  end subroutine inlist_ts_link
+
+  subroutine inlist_ts_update(this)
+    ! -- modules
+    use StructVectorModule, only: TSStringLocType
+    use StructVectorModule, only: StructVectorType
+    ! -- dummy
+    class(StressListInputType), intent(inout) :: this
+    ! -- locals
+    integer(I4B) :: n, m
+    type(TSStringLocType), pointer :: ts_strloc
+    type(StructVectorType), pointer :: sv
+    !
+    !
+    do m = 1, this%structarray%count()
+
+      sv => this%structarray%get(m)
+
+      if (sv%idt%timeseries) then
+        !
+        do n = 1, sv%ts_strlocs%count()
+          ts_strloc => sv%get_ts_strloc(n)
+          call this%ts_link(sv, ts_strloc)
+        end do
+        !
+        call sv%clear()
+      end if
+    end do
+    !
+    ! -- return
+    return
+  end subroutine inlist_ts_update
+
+  subroutine create_structarray(this)
+    ! -- modules
+    use InputDefinitionModule, only: InputParamDefinitionType
+    use DefinitionSelectModule, only: get_param_definition_type
+    ! -- dummy
+    class(StressListInputType), intent(inout) :: this
+    ! -- locals
+    type(InputParamDefinitionType), pointer :: idt
+    integer(I4B) :: icol
+    !
+    ! -- construct and set up the struct array object
+    this%structarray => constructStructArray(this%mf6_input, this%ncol, &
+                                             this%bndctx%maxbound, 0, &
+                                             this%mf6_input%mempath, &
+                                             this%mf6_input%component_mempath)
+    !
+    ! -- set up struct array
+    do icol = 1, this%ncol
+      !
+      idt => get_param_definition_type(this%mf6_input%param_dfns, &
+                                       this%mf6_input%component_type, &
+                                       this%mf6_input%subcomponent_type, &
+                                       'PERIOD', &
+                                       this%cols(icol), this%sourcename)
+      !
+      ! -- allocate variable in memory manager
+      call this%structarray%mem_create_vector(icol, idt)
+      !
+      ! -- store boundname index when found
+      if (idt%mf6varname == 'BOUNDNAME') this%iboundname = icol
+      !
+    end do
+    !
+    ! -- return
+    return
+  end subroutine create_structarray
+
+  subroutine read_control_record(this, parser)
+    ! -- modules
+    use InputOutputModule, only: urword
+    use OpenSpecModule, only: form, access
+    use ConstantsModule, only: LINELENGTH
+    use BlockParserModule, only: BlockParserType
+    ! -- dummy
+    class(StressListInputType), intent(inout) :: this
+    type(BlockParserType), intent(inout) :: parser
+    ! -- local
+    integer(I4B) :: lloc, istart, istop, idum, inunit, itmp, ierr
+    integer(I4B) :: nunopn = 99
+    character(len=:), allocatable :: line
+    character(len=LINELENGTH) :: fname
+    logical :: exists
+    real(DP) :: r
+    ! -- formats
+    character(len=*), parameter :: fmtocne = &
+      &"('Specified OPEN/CLOSE file ',(A),' does not exist')"
+    character(len=*), parameter :: fmtobf = &
+      &"(1X,/1X,'OPENING BINARY FILE ON UNIT ',I0,':',/1X,A)"
+    !
+    inunit = parser%getunit()
+    !
+    ! -- Read to the first non-commented line
+    lloc = 1
+    call parser%line_reader%rdcom(inunit, this%iout, line, ierr)
+    call urword(line, lloc, istart, istop, 1, idum, r, this%iout, inunit)
+    !
+    if (line(istart:istop) == 'OPEN/CLOSE') then
+      !
+      ! -- get filename
+      call urword(line, lloc, istart, istop, 0, idum, r, &
+                  this%iout, inunit)
+      !
+      fname = line(istart:istop)
+      !
+      ! -- check to see if file OPEN/CLOSE file exists
+      inquire (file=fname, exist=exists)
+      !
+      if (.not. exists) then
+        write (errmsg, fmtocne) line(istart:istop)
+        call store_error(errmsg)
+        call store_error('Specified OPEN/CLOSE file does not exist')
+        call store_error_unit(inunit)
+      end if
+      !
+      ! -- Check for (BINARY) keyword
+      call urword(line, lloc, istart, istop, 1, idum, r, &
+                  this%iout, inunit)
+      !
+      if (line(istart:istop) == '(BINARY)') this%ibinary = 1
+      !
+      ! -- Open the file depending on ibinary flag
+      if (this%ibinary == 1) then
+        this%oc_inunit = nunopn
+        itmp = this%iout
+        !
+        if (this%iout > 0) then
+          itmp = 0
+          write (this%iout, fmtobf) this%oc_inunit, trim(adjustl(fname))
+        end if
+        !
+        call openfile(this%oc_inunit, itmp, fname, 'OPEN/CLOSE', &
+                      fmtarg_opt=form, accarg_opt=access)
+      end if
+    end if
+    !
+    if (this%ibinary == 0) then
+      call parser%line_reader%bkspc(parser%getunit())
+    end if
+    !
+    ! -- return
+    return
+  end subroutine read_control_record
+
+end module StressListInputModule
diff --git a/src/Utilities/Idm/mf6blockfile/StructArray.f90 b/src/Utilities/Idm/mf6blockfile/StructArray.f90
index 5dca7d8becd..49befb0b53a 100644
--- a/src/Utilities/Idm/mf6blockfile/StructArray.f90
+++ b/src/Utilities/Idm/mf6blockfile/StructArray.f90
@@ -8,16 +8,17 @@
 module StructArrayModule
 
   use KindModule, only: I4B, DP, LGP
-  use ConstantsModule, only: DNODATA, LINELENGTH
+  use ConstantsModule, only: DZERO, IZERO, LINELENGTH, LENMEMPATH, LENVARNAME
   use SimVariablesModule, only: errmsg
   use SimModule, only: store_error
   use StructVectorModule, only: StructVectorType
+  use InputDefinitionModule, only: InputParamDefinitionType
   use MemoryManagerModule, only: mem_allocate, mem_reallocate, mem_setptr
   use CharacterStringModule, only: CharacterStringType
   use STLVecIntModule, only: STLVecInt
   use IdmLoggerModule, only: idm_log_var
-  use MemoryManagerModule, only: mem_setptr
   use BlockParserModule, only: BlockParserType
+  use ModflowInputModule, only: ModflowInputType
 
   implicit none
   private
@@ -37,14 +38,23 @@ module StructArrayModule
     integer(I4B) :: blocknum
     logical(LGP) :: deferred_shape = .false.
     integer(I4B) :: deferred_size_init = 5
-    type(StructVectorType), dimension(:), allocatable :: struct_vector_1d
+    character(len=LENMEMPATH) :: mempath
+    character(len=LENMEMPATH) :: component_mempath
+    type(StructVectorType), dimension(:), allocatable :: struct_vectors
+    integer(I4B), dimension(:), allocatable :: startidx
+    integer(I4B), dimension(:), allocatable :: numcols
+    type(ModflowInputType) :: mf6_input
   contains
     procedure :: mem_create_vector
-    procedure :: add_vector_int1d
-    procedure :: add_vector_dbl1d
-    procedure :: add_vector_charstr1d
-    procedure :: add_vector_intvector
+    procedure :: count
+    procedure :: get
+    procedure :: allocate_int_type
+    procedure :: allocate_dbl_type
+    procedure :: allocate_charstr_type
+    procedure :: allocate_int1d_type
+    procedure :: allocate_dbl1d_type
     procedure :: read_from_parser
+    procedure :: read_from_binary
     procedure :: memload_vectors
     procedure :: load_deferred_vector
     procedure :: log_structarray_vars
@@ -56,23 +66,28 @@ module StructArrayModule
 
   !> @brief constructor for a struct_array
   !<
-  function constructStructArray(ncol, nrow, blocknum) result(struct_array)
+  function constructStructArray(mf6_input, ncol, nrow, blocknum, mempath, &
+                                component_mempath) result(struct_array)
+    type(ModflowInputType), intent(in) :: mf6_input
     integer(I4B), intent(in) :: ncol !< number of columns in the StructArrayType
-    integer(I4B), pointer, intent(in) :: nrow !< number of rows in the StructArrayType
+    integer(I4B), intent(in) :: nrow !< number of rows in the StructArrayType
     integer(I4B), intent(in) :: blocknum !< valid block number or 0
+    character(len=*), intent(in) :: mempath !< memory path for storing the vector
+    character(len=*), intent(in) :: component_mempath
     type(StructArrayType), pointer :: struct_array !< new StructArrayType
     !
     ! -- allocate StructArrayType
     allocate (struct_array)
     !
+    ! -- set description of input
+    struct_array%mf6_input = mf6_input
+    !
     ! -- set number of arrays
     struct_array%ncol = ncol
     !
     ! -- set rows if known or set deferred
-    if (associated(nrow)) then
-      struct_array%nrow = nrow
-    else
-      struct_array%nrow = 0
+    struct_array%nrow = nrow
+    if (struct_array%nrow == 0) then
       struct_array%deferred_shape = .true.
     end if
     !
@@ -83,8 +98,14 @@ function constructStructArray(ncol, nrow, blocknum) result(struct_array)
       struct_array%blocknum = 0
     end if
     !
+    !
+    struct_array%mempath = mempath
+    struct_array%component_mempath = component_mempath
+    !
     ! -- allocate StructVectorType objects
-    allocate (struct_array%struct_vector_1d(ncol))
+    allocate (struct_array%struct_vectors(ncol))
+    allocate (struct_array%startidx(ncol))
+    allocate (struct_array%numcols(ncol))
   end function constructStructArray
 
   !> @brief destructor for a struct_array
@@ -92,317 +113,417 @@ end function constructStructArray
   subroutine destructStructArray(struct_array)
     type(StructArrayType), pointer, intent(inout) :: struct_array !< StructArrayType to destroy
 
-    deallocate (struct_array%struct_vector_1d)
+    deallocate (struct_array%struct_vectors)
+    deallocate (struct_array%startidx)
+    deallocate (struct_array%numcols)
     deallocate (struct_array)
     nullify (struct_array)
   end subroutine destructStructArray
 
   !> @brief create new vector in StructArrayType
   !<
-  subroutine mem_create_vector(this, icol, vartype, name, tagname, memoryPath, &
-                               varname_shape, preserve_case)
+  subroutine mem_create_vector(this, icol, idt)
     class(StructArrayType) :: this !< StructArrayType
     integer(I4B), intent(in) :: icol !< column to create
-    character(len=*), intent(in) :: vartype !< type of column to create
-    character(len=*), intent(in) :: name !< name of the column to create
-    character(len=*), intent(in) :: tagname
-    character(len=*), intent(in) :: memoryPath !< memory path for storing the vector
-    character(len=*), intent(in) :: varname_shape !< shape
-    logical(LGP), optional, intent(in) :: preserve_case !< flag indicating whether or not to preserve case
-    integer(I4B), dimension(:), pointer, contiguous :: int1d
-    real(DP), dimension(:), pointer, contiguous :: dbl1d
-    type(CharacterStringType), dimension(:), pointer, contiguous :: charstr1d
-    type(STLVecInt), pointer :: intvector
-    integer(I4B) :: j
-    integer(I4B) :: inodata = 999 !todo: create INODATA in constants?
+    type(InputParamDefinitionType), pointer :: idt
+    type(StructVectorType) :: sv
+    integer(I4B) :: numcol
+    !
+    numcol = 1
+    !
+    sv%idt => idt
+    sv%icol = icol
+    !
+    ! -- set size
+    if (this%deferred_shape) then
+      sv%size = this%deferred_size_init
+    else
+      sv%size = this%nrow
+    end if
     !
     ! -- allocate array memory for StructVectorType
-    select case (vartype)
-      !
-    case ('INTEGER1D')
-      !
-      ! -- allocate intvector object
-      allocate (intvector)
-      !
-      ! -- initialize StructVector and add to StructArray
-      call this%add_vector_intvector(name, tagname, memoryPath, varname_shape, &
-                                     icol, intvector)
+    select case (idt%datatype)
       !
     case ('INTEGER')
       !
-      if (this%deferred_shape) then
-        ! -- shape not known, allocate locally
-        allocate (int1d(this%deferred_size_init))
-      else
-        ! -- shape known, allocate in managed memory
-        call mem_allocate(int1d, this%nrow, name, memoryPath)
-      end if
-      !
-      ! -- initialize vector values
-      do j = 1, this%nrow
-        int1d(j) = inodata
-      end do
-      !
-      ! -- initialize StructVector and add to StructArray
-      call this%add_vector_int1d(name, tagname, memoryPath, icol, int1d)
+      call this%allocate_int_type(sv)
       !
     case ('DOUBLE')
       !
-      call mem_allocate(dbl1d, this%nrow, name, memoryPath)
+      call this%allocate_dbl_type(sv)
       !
-      do j = 1, this%nrow
-        dbl1d(j) = DNODATA
-      end do
+    case ('STRING', 'KEYWORD')
       !
-      call this%add_vector_dbl1d(name, tagname, memoryPath, icol, dbl1d)
+      call this%allocate_charstr_type(sv)
       !
-    case ('STRING', 'KEYWORD')
+    case ('INTEGER1D')
       !
-      if (this%deferred_shape) then
-        allocate (charstr1d(this%deferred_size_init))
-      else
-        call mem_allocate(charstr1d, LINELENGTH, this%nrow, name, memoryPath)
+      call this%allocate_int1d_type(sv)
+      if (sv%memtype == 5) then
+        numcol = sv%intshape
       end if
       !
-      do j = 1, this%nrow
-        charstr1d(j) = ''
-      end do
+    case ('DOUBLE1D')
+      !
+      call this%allocate_dbl1d_type(sv)
+      numcol = sv%intshape
       !
-      call this%add_vector_charstr1d(name, tagname, memoryPath, icol, charstr1d, &
-                                     varname_shape, preserve_case)
     end select
-
+    !
+    ! -- set the object in the Struct Array
+    this%struct_vectors(icol) = sv
+    !
+    this%numcols(icol) = numcol
+    if (icol == 1) then
+      this%startidx(icol) = 1
+    else
+      this%startidx(icol) = this%startidx(icol - 1) + this%numcols(icol - 1)
+    end if
+    !
+    ! -- return
     return
   end subroutine mem_create_vector
 
-  !> @brief add int1d to StructArrayType
+  function count(this)
+    class(StructArrayType) :: this !< StructArrayType
+    integer(I4B) :: count
+    count = size(this%struct_vectors)
+  end function count
+
+  subroutine set_pointer(sv, sv_target)
+    type(StructVectorType), pointer :: sv
+    type(StructVectorType), target :: sv_target
+    sv => sv_target
+  end subroutine set_pointer
+
+  function get(this, idx) result(sv)
+    class(StructArrayType) :: this !< StructArrayType
+    integer(I4B), intent(in) :: idx
+    type(StructVectorType), pointer :: sv
+    call set_pointer(sv, this%struct_vectors(idx))
+  end function get
+
+  !> @brief allocate integer input type
   !<
-  subroutine add_vector_int1d(this, varname, tagname, memoryPath, icol, int1d)
+  subroutine allocate_int_type(this, sv)
     class(StructArrayType) :: this !< StructArrayType
-    character(len=*), intent(in) :: varname !< name of the variable
-    character(len=*), intent(in) :: tagname
-    character(len=*), intent(in) :: memoryPath !< memory path to vector
-    integer(I4B), intent(in) :: icol !< column of the vector
-    integer(I4B), dimension(:), pointer, contiguous, intent(in) :: int1d !< vector to add
-    type(StructVectorType) :: sv
-    !
-    ! -- initialize StructVectorType
-    sv%varname = varname
-    sv%tagname = tagname
-    sv%shapevar = ''
-    sv%mempath = memoryPath
-    sv%memtype = 1
-    sv%int1d => int1d
+    type(StructVectorType), intent(inout) :: sv
+    integer(I4B), dimension(:), pointer, contiguous :: int1d
+    integer(I4B) :: j
     !
-    ! -- set size
     if (this%deferred_shape) then
-      sv%size = this%deferred_size_init
+      ! -- shape not known, allocate locally
+      allocate (int1d(this%deferred_size_init))
     else
-      sv%size = this%nrow
+      ! -- shape known, allocate in managed memory
+      call mem_allocate(int1d, this%nrow, sv%idt%mf6varname, this%mempath)
     end if
     !
-    ! -- set the object in the Struct Array
-    this%struct_vector_1d(icol) = sv
+    ! -- initialize vector values
+    do j = 1, this%nrow
+      int1d(j) = IZERO
+    end do
+    !
+    sv%memtype = 1
+    sv%int1d => int1d
     !
     ! -- return
     return
-  end subroutine add_vector_int1d
+  end subroutine allocate_int_type
 
-  !> @brief add dbl1d to StructArrayType
+  !> @brief allocate double input type
   !<
-  subroutine add_vector_dbl1d(this, varname, tagname, memoryPath, icol, dbl1d)
+  subroutine allocate_dbl_type(this, sv)
     class(StructArrayType) :: this !< StructArrayType
-    character(len=*), intent(in) :: varname !< name of the variable
-    character(len=*), intent(in) :: tagname
-    character(len=*), intent(in) :: memoryPath !< memory path to vector
-    integer(I4B), intent(in) :: icol !< column of the vector
-    real(DP), dimension(:), pointer, contiguous, intent(in) :: dbl1d !< vector to add
-    type(StructVectorType) :: sv
+    type(StructVectorType), intent(inout) :: sv
+    real(DP), dimension(:), pointer, contiguous :: dbl1d
+    integer(I4B) :: j
+    !
+    if (this%deferred_shape) then
+      ! -- shape not known, allocate locally
+      allocate (dbl1d(this%deferred_size_init))
+    else
+      ! -- shape known, allocate in managed memory
+      call mem_allocate(dbl1d, this%nrow, sv%idt%mf6varname, this%mempath)
+    end if
+    !
+    do j = 1, this%nrow
+      dbl1d(j) = DZERO
+    end do
     !
-    ! -- initialize StructVectorType
-    sv%varname = varname
-    sv%tagname = tagname
-    sv%shapevar = ''
-    sv%mempath = memoryPath
     sv%memtype = 2
     sv%dbl1d => dbl1d
-    sv%size = this%nrow
-    !
-    ! -- set the object in the Struct Array
-    this%struct_vector_1d(icol) = sv
     !
     ! -- return
     return
-  end subroutine add_vector_dbl1d
+  end subroutine allocate_dbl_type
 
-  !> @brief add charstr1d to StructArrayType
+  !> @brief allocate charstr input type
   !<
-  subroutine add_vector_charstr1d(this, varname, tagname, memoryPath, icol, &
-                                  charstr1d, varname_shape, preserve_case)
+  subroutine allocate_charstr_type(this, sv)
     class(StructArrayType) :: this !< StructArrayType
-    integer(I4B), intent(in) :: icol !< column of the vector
-    character(len=*), intent(in) :: varname !< name of the variable
-    character(len=*), intent(in) :: tagname
-    character(len=*), intent(in) :: memoryPath !< memory path to vector
-    type(CharacterStringType), dimension(:), pointer, contiguous, intent(in) :: &
-      charstr1d !< vector to add
-    character(len=*), intent(in) :: varname_shape !< shape of variable
-    logical(LGP), intent(in) :: preserve_case
-    type(StructVectorType) :: sv
-    !
-    ! -- initialize StructVectorType
-    sv%varname = varname
-    sv%tagname = tagname
-    sv%shapevar = varname_shape
-    sv%mempath = memoryPath
-    sv%memtype = 3
-    sv%preserve_case = preserve_case
-    sv%charstr1d => charstr1d
+    type(StructVectorType), intent(inout) :: sv
+    type(CharacterStringType), dimension(:), pointer, contiguous :: charstr1d
+    integer(I4B) :: j
     !
-    ! -- set size
     if (this%deferred_shape) then
-      sv%size = this%deferred_size_init
+      allocate (charstr1d(this%deferred_size_init))
     else
-      sv%size = this%nrow
+      call mem_allocate(charstr1d, LINELENGTH, this%nrow, &
+                        sv%idt%mf6varname, this%mempath)
     end if
     !
-    ! -- set the object in the Struct Array
-    this%struct_vector_1d(icol) = sv
+    do j = 1, this%nrow
+      charstr1d(j) = ''
+    end do
+    !
+    sv%memtype = 3
+    sv%charstr1d => charstr1d
     !
     ! -- return
     return
-  end subroutine add_vector_charstr1d
+  end subroutine allocate_charstr_type
 
-  !> @brief add STLVecInt to StructArrayType
+  !> @brief allocate int1d input type
   !<
-  subroutine add_vector_intvector(this, varname, tagname, memoryPath, &
-                                  varname_shape, icol, intvector)
+  subroutine allocate_int1d_type(this, sv)
+    use ConstantsModule, only: LENMODELNAME
+    use MemoryHelperModule, only: create_mem_path
+    use SimVariablesModule, only: idm_context
     class(StructArrayType) :: this !< StructArrayType
-    character(len=*), intent(in) :: varname !< name of the variable
-    character(len=*), intent(in) :: tagname
-    character(len=*), intent(in) :: memoryPath !< memory path to vector
-    character(len=*), intent(in) :: varname_shape !< shape of variable
-    integer(I4B), intent(in) :: icol !< column of the vector
-    type(STLVecInt), pointer, intent(in) :: intvector !< vector to add
-    type(StructVectorType) :: sv
-    !
-    ! -- initialize STLVecInt
-    call intvector%init()
+    type(StructVectorType), intent(inout) :: sv
+    integer(I4B), dimension(:, :), pointer, contiguous :: int2d
+    type(STLVecInt), pointer :: intvector
+    integer(I4B), pointer :: ncelldim, exgid
+    character(len=LENMEMPATH) :: input_mempath
+    character(len=LENMODELNAME) :: mname
+    type(CharacterStringType), dimension(:), contiguous, &
+      pointer :: charstr1d
     !
-    ! -- set pointer to dynamic shape
-    call mem_setptr(sv%intvector_shape, varname_shape, memoryPath)
+    if (sv%idt%shape == 'NCELLDIM') then
+      !
+      ! -- if EXCHANGE set to NCELLDIM of appropriate model
+      if (this%mf6_input%component_type == 'EXG') then
+        !
+        ! -- set pointer to EXGID
+        call mem_setptr(exgid, 'EXGID', this%mf6_input%mempath)
+        !
+        ! -- set pointer to appropriate exchange model array
+        input_mempath = create_mem_path('SIM', 'NAM', idm_context)
+        !
+        if (sv%idt%tagname == 'CELLIDM1') then
+          call mem_setptr(charstr1d, 'EXGMNAMEA', input_mempath)
+        else if (sv%idt%tagname == 'CELLIDM2') then
+          call mem_setptr(charstr1d, 'EXGMNAMEB', input_mempath)
+        end if
+        !
+        ! -- set the model name
+        mname = charstr1d(exgid)
+        !
+        ! -- set ncelldim pointer
+        input_mempath = create_mem_path(component=mname, context=idm_context)
+        call mem_setptr(ncelldim, sv%idt%shape, input_mempath)
+      else
+        !
+        call mem_setptr(ncelldim, sv%idt%shape, this%component_mempath)
+      end if
+      !
+      if (this%deferred_shape) then
+        ! -- shape not known, allocate locally
+        allocate (int2d(ncelldim, this%deferred_size_init))
+      else
+        ! -- shape known, allocate in managed memory
+        call mem_allocate(int2d, ncelldim, this%nrow, &
+                          sv%idt%mf6varname, this%mempath)
+      end if
+      !
+      ! -- initialize
+      int2d = IZERO
+      !
+      sv%memtype = 5
+      sv%int2d => int2d
+      sv%intshape => ncelldim
+      !
+    else
+      !
+      ! -- allocate intvector object
+      allocate (intvector)
+      !
+      ! -- initialize STLVecInt
+      call intvector%init()
+      !
+      sv%memtype = 4
+      sv%intvector => intvector
+      sv%size = -1
+      !
+      ! -- set pointer to dynamic shape
+      call mem_setptr(sv%intvector_shape, sv%idt%shape, this%mempath)
+    end if
     !
-    ! -- initialize StructVectorType
-    sv%varname = varname
-    sv%tagname = tagname
-    sv%shapevar = varname_shape
-    sv%mempath = memoryPath
-    sv%memtype = 4
-    sv%intvector => intvector
-    sv%size = -1
+    ! -- return
+    return
+  end subroutine allocate_int1d_type
+
+  !> @brief allocate dbl1d input type
+  !<
+  subroutine allocate_dbl1d_type(this, sv)
+    use MemoryManagerModule, only: get_isize
+    class(StructArrayType) :: this !< StructArrayType
+    type(StructVectorType), intent(inout) :: sv
+    real(DP), dimension(:, :), pointer, contiguous :: dbl2d
+    integer(I4B), pointer :: naux, nseg, nseg_1
+    integer(I4B) :: nseg1_isize
     !
-    ! -- set the object in the Struct Array
-    this%struct_vector_1d(icol) = sv
+    if (sv%idt%shape == 'NAUX') then
+      call mem_setptr(naux, sv%idt%shape, this%mempath)
+      !
+      call mem_allocate(dbl2d, naux, this%nrow, sv%idt%mf6varname, this%mempath)
+      !
+      ! -- initialize
+      dbl2d = DZERO
+      !
+      sv%memtype = 6
+      sv%dbl2d => dbl2d
+      sv%intshape => naux
+      !
+    else if (sv%idt%shape == 'NSEG-1') then
+      call mem_setptr(nseg, 'NSEG', this%mempath)
+      !
+      call get_isize('NSEG_1', this%mempath, nseg1_isize)
+      !
+      if (nseg1_isize < 0) then
+        call mem_allocate(nseg_1, 'NSEG_1', this%mempath)
+        nseg_1 = nseg - 1
+      else
+        call mem_setptr(nseg_1, 'NSEG_1', this%mempath)
+      end if
+      !
+      call mem_allocate(dbl2d, nseg_1, this%nrow, sv%idt%mf6varname, this%mempath)
+      !
+      ! -- initialize
+      dbl2d = DZERO
+      !
+      sv%memtype = 6
+      sv%dbl2d => dbl2d
+      sv%intshape => nseg_1
+      !
+    else
+      errmsg = 'Programming error. IDM SA 2d real input param unsupported &
+               &shape "'//trim(sv%idt%shape)//'".'
+      call store_error(errmsg, terminate=.TRUE.)
+    end if
     !
     ! -- return
     return
-  end subroutine add_vector_intvector
+  end subroutine allocate_dbl1d_type
 
   subroutine load_deferred_vector(this, icol)
     use MemoryManagerModule, only: get_isize
     class(StructArrayType) :: this !< StructArrayType
     integer(I4B), intent(in) :: icol
-    integer(I4B) :: i, isize
+    integer(I4B) :: i, j, isize
     integer(I4B), dimension(:), pointer, contiguous :: p_int1d
+    integer(I4B), dimension(:, :), pointer, contiguous :: p_int2d
     real(DP), dimension(:), pointer, contiguous :: p_dbl1d
     type(CharacterStringType), dimension(:), pointer, contiguous :: p_charstr1d
+    character(len=LENVARNAME) :: varname
+    !
+    ! -- set varname
+    varname = this%struct_vectors(icol)%idt%mf6varname
     !
     ! -- check if already mem managed variable
-    call get_isize(this%struct_vector_1d(icol)%varname, &
-                   this%struct_vector_1d(icol)%mempath, isize)
+    call get_isize(varname, this%mempath, isize)
     !
     ! -- allocate and load based on memtype
-    select case (this%struct_vector_1d(icol)%memtype)
+    select case (this%struct_vectors(icol)%memtype)
       !
     case (1) ! -- memtype integer
       !
       if (isize > 0) then
         ! -- variable exists, reallocate and append
-        call mem_setptr(p_int1d, this%struct_vector_1d(icol)%varname, &
-                        this%struct_vector_1d(icol)%mempath)
+        call mem_setptr(p_int1d, varname, this%mempath)
         ! -- Currently deferred vectors are appended to managed
         !    memory vectors when they are already allocated
         !    (e.g. SIMNAM SolutionGroup)
-        call mem_reallocate(p_int1d, this%nrow + isize, &
-                            this%struct_vector_1d(icol)%varname, &
-                            this%struct_vector_1d(icol)%mempath)
+        call mem_reallocate(p_int1d, this%nrow + isize, varname, this%mempath)
 
         do i = 1, this%nrow
-          p_int1d(isize + i) = this%struct_vector_1d(icol)%int1d(i)
+          p_int1d(isize + i) = this%struct_vectors(icol)%int1d(i)
         end do
       else
         !
         ! -- allocate memory manager vector
-        call mem_allocate(p_int1d, this%nrow, &
-                          this%struct_vector_1d(icol)%varname, &
-                          this%struct_vector_1d(icol)%mempath)
+        call mem_allocate(p_int1d, this%nrow, varname, this%mempath)
         !
         ! -- load local vector to managed memory
         do i = 1, this%nrow
-          p_int1d(i) = this%struct_vector_1d(icol)%int1d(i)
+          p_int1d(i) = this%struct_vectors(icol)%int1d(i)
         end do
       end if
       !
       ! -- deallocate local memory
-      deallocate (this%struct_vector_1d(icol)%int1d)
+      deallocate (this%struct_vectors(icol)%int1d)
       !
       ! -- update structvector
-      this%struct_vector_1d(icol)%int1d => p_int1d
-      this%struct_vector_1d(icol)%size = this%nrow
+      this%struct_vectors(icol)%int1d => p_int1d
+      this%struct_vectors(icol)%size = this%nrow
       !
     case (2) ! -- memtype real
       !
-      call mem_allocate(p_dbl1d, this%nrow, &
-                        this%struct_vector_1d(icol)%varname, &
-                        this%struct_vector_1d(icol)%mempath)
+      call mem_allocate(p_dbl1d, this%nrow, varname, this%mempath)
       !
       do i = 1, this%nrow
-        p_dbl1d(i) = this%struct_vector_1d(icol)%dbl1d(i)
+        p_dbl1d(i) = this%struct_vectors(icol)%dbl1d(i)
       end do
       !
-      deallocate (this%struct_vector_1d(icol)%dbl1d)
+      deallocate (this%struct_vectors(icol)%dbl1d)
       !
       ! --
-      this%struct_vector_1d(icol)%dbl1d => p_dbl1d
-      this%struct_vector_1d(icol)%size = this%nrow
+      this%struct_vectors(icol)%dbl1d => p_dbl1d
+      this%struct_vectors(icol)%size = this%nrow
       !
     case (3) ! -- memtype charstring
       if (isize > 0) then
-        call mem_setptr(p_charstr1d, this%struct_vector_1d(icol)%varname, &
-                        this%struct_vector_1d(icol)%mempath)
-        call mem_reallocate(p_charstr1d, LINELENGTH, this%nrow + isize, &
-                            this%struct_vector_1d(icol)%varname, &
-                            this%struct_vector_1d(icol)%mempath)
+        call mem_setptr(p_charstr1d, varname, this%mempath)
+        call mem_reallocate(p_charstr1d, LINELENGTH, this%nrow + isize, varname, &
+                            this%mempath)
 
         do i = 1, this%nrow
-          p_charstr1d(isize + i) = this%struct_vector_1d(icol)%charstr1d(i)
+          p_charstr1d(isize + i) = this%struct_vectors(icol)%charstr1d(i)
         end do
       else
         !
-        call mem_allocate(p_charstr1d, LINELENGTH, this%nrow, &
-                          this%struct_vector_1d(icol)%varname, &
-                          this%struct_vector_1d(icol)%mempath)
+        call mem_allocate(p_charstr1d, LINELENGTH, this%nrow, varname, &
+                          this%mempath)
         !
         do i = 1, this%nrow
-          p_charstr1d(i) = this%struct_vector_1d(icol)%charstr1d(i)
+          p_charstr1d(i) = this%struct_vectors(icol)%charstr1d(i)
         end do
       end if
       !
-      deallocate (this%struct_vector_1d(icol)%charstr1d)
+      deallocate (this%struct_vectors(icol)%charstr1d)
       !
     case (4) ! -- memtype intvector
       ! no-op
+    case (5)
+      call mem_allocate(p_int2d, this%struct_vectors(icol)%intshape, this%nrow, &
+                        varname, this%mempath)
+      !
+      do i = 1, this%nrow
+        do j = 1, this%struct_vectors(icol)%intshape
+          p_int2d(j, i) = this%struct_vectors(icol)%int2d(j, i)
+        end do
+      end do
+      !
+      deallocate (this%struct_vectors(icol)%int2d)
+      !
+      this%struct_vectors(icol)%int2d => p_int2d
+      this%struct_vectors(icol)%size = this%nrow
+      !
+      ! TODO: case (6)
     case default
+      errmsg = 'Programming error. IDM load_deferred_vector unsupported memtype.'
+      call store_error(errmsg, terminate=.TRUE.)
     end select
     !
     ! -- return
@@ -415,30 +536,33 @@ subroutine memload_vectors(this)
     class(StructArrayType) :: this !< StructArrayType
     integer(I4B) :: icol, j
     integer(I4B), dimension(:), pointer, contiguous :: p_intvector
+    character(len=LENVARNAME) :: varname
     !
     do icol = 1, this%ncol
       !
-      if (this%struct_vector_1d(icol)%memtype == 4) then
+      ! -- set varname
+      varname = this%struct_vectors(icol)%idt%mf6varname
+      !
+      if (this%struct_vectors(icol)%memtype == 4) then
         ! -- intvectors always need to be loaded
         !
         ! -- size intvector to number of values read
-        call this%struct_vector_1d(icol)%intvector%shrink_to_fit()
+        call this%struct_vectors(icol)%intvector%shrink_to_fit()
         !
         ! -- allocate memory manager vector
         call mem_allocate(p_intvector, &
-                          this%struct_vector_1d(icol)%intvector%size, &
-                          this%struct_vector_1d(icol)%varname, &
-                          this%struct_vector_1d(icol)%mempath)
+                          this%struct_vectors(icol)%intvector%size, &
+                          varname, this%mempath)
         !
         ! -- load local vector to managed memory
-        do j = 1, this%struct_vector_1d(icol)%intvector%size
-          p_intvector(j) = this%struct_vector_1d(icol)%intvector%at(j)
+        do j = 1, this%struct_vectors(icol)%intvector%size
+          p_intvector(j) = this%struct_vectors(icol)%intvector%at(j)
         end do
         !
         ! -- cleanup local memory
-        call this%struct_vector_1d(icol)%intvector%destroy()
-        deallocate (this%struct_vector_1d(icol)%intvector)
-        nullify (this%struct_vector_1d(icol)%intvector_shape)
+        call this%struct_vectors(icol)%intvector%destroy()
+        deallocate (this%struct_vectors(icol)%intvector)
+        nullify (this%struct_vectors(icol)%intvector_shape)
         !
       else if (this%deferred_shape) then
         !
@@ -463,27 +587,49 @@ subroutine log_structarray_vars(this, iout)
     do j = 1, this%ncol
       !
       ! -- log based on memtype
-      select case (this%struct_vector_1d(j)%memtype)
+      select case (this%struct_vectors(j)%memtype)
         !
       case (1) ! -- memtype integer
         !
-        call idm_log_var(this%struct_vector_1d(j)%int1d, &
-                         this%struct_vector_1d(j)%tagname, &
-                         this%struct_vector_1d(j)%mempath, iout)
+        call idm_log_var(this%struct_vectors(j)%int1d, &
+                         this%struct_vectors(j)%idt%tagname, &
+                         this%mempath, iout)
         !
       case (2) ! -- memtype real
         !
-        call idm_log_var(this%struct_vector_1d(j)%dbl1d, &
-                         this%struct_vector_1d(j)%tagname, &
-                         this%struct_vector_1d(j)%mempath, iout)
+        if (this%struct_vectors(j)%ts_strlocs%count() > 0) then
+          call idm_log_var(this%struct_vectors(j)%idt%tagname, &
+                           this%mempath, iout, .false.)
+        else
+          call idm_log_var(this%struct_vectors(j)%dbl1d, &
+                           this%struct_vectors(j)%idt%tagname, &
+                           this%mempath, iout)
+        end if
         !
       case (4) ! -- memtype intvector
         !
-        call mem_setptr(int1d, this%struct_vector_1d(j)%varname, &
-                        this%struct_vector_1d(j)%mempath)
+        call mem_setptr(int1d, this%struct_vectors(j)%idt%mf6varname, &
+                        this%mempath)
+        !
+        call idm_log_var(int1d, this%struct_vectors(j)%idt%tagname, &
+                         this%mempath, iout)
+        !
+      case (5) ! -- memtype int2d
+        !
+        call idm_log_var(this%struct_vectors(j)%int2d, &
+                         this%struct_vectors(j)%idt%tagname, &
+                         this%mempath, iout)
         !
-        call idm_log_var(int1d, this%struct_vector_1d(j)%tagname, &
-                         this%struct_vector_1d(j)%mempath, iout)
+      case (6) ! -- memtype dbl2d
+        !
+        if (this%struct_vectors(j)%ts_strlocs%count() > 0) then
+          call idm_log_var(this%struct_vectors(j)%idt%tagname, &
+                           this%mempath, iout, .false.)
+        else
+          call idm_log_var(this%struct_vectors(j)%dbl2d, &
+                           this%struct_vectors(j)%idt%tagname, &
+                           this%mempath, iout)
+        end if
         !
       end select
       !
@@ -497,8 +643,9 @@ end subroutine log_structarray_vars
   !<
   subroutine check_reallocate(this)
     class(StructArrayType) :: this !< StructArrayType
-    integer(I4B) :: i, j, newsize
+    integer(I4B) :: i, j, k, newsize
     integer(I4B), dimension(:), pointer, contiguous :: p_int1d
+    integer(I4B), dimension(:, :), pointer, contiguous :: p_int2d
     real(DP), dimension(:), pointer, contiguous :: p_dbl1d
     type(CharacterStringType), dimension(:), pointer, contiguous :: p_charstr1d
     integer(I4B) :: reallocate_mult
@@ -509,66 +656,87 @@ subroutine check_reallocate(this)
     do j = 1, this%ncol
       !
       ! -- reallocate based on memtype
-      select case (this%struct_vector_1d(j)%memtype)
+      select case (this%struct_vectors(j)%memtype)
         !
       case (1) ! -- memtype integer
         !
         ! -- check if more space needed
-        if (this%nrow > this%struct_vector_1d(j)%size) then
+        if (this%nrow > this%struct_vectors(j)%size) then
           !
           ! -- calculate new size
-          newsize = this%struct_vector_1d(j)%size * reallocate_mult
+          newsize = this%struct_vectors(j)%size * reallocate_mult
           !
           ! -- allocate new vector
           allocate (p_int1d(newsize))
           !
           ! -- copy from old to new
-          do i = 1, this%struct_vector_1d(j)%size
-            p_int1d(i) = this%struct_vector_1d(j)%int1d(i)
+          do i = 1, this%struct_vectors(j)%size
+            p_int1d(i) = this%struct_vectors(j)%int1d(i)
           end do
           !
           ! -- deallocate old vector
-          deallocate (this%struct_vector_1d(j)%int1d)
+          deallocate (this%struct_vectors(j)%int1d)
           !
           ! -- update struct array object
-          this%struct_vector_1d(j)%int1d => p_int1d
-          this%struct_vector_1d(j)%size = newsize
+          this%struct_vectors(j)%int1d => p_int1d
+          this%struct_vectors(j)%size = newsize
         end if
         !
       case (2) ! -- memtype real
-        if (this%nrow > this%struct_vector_1d(j)%size) then
+        if (this%nrow > this%struct_vectors(j)%size) then
           !
-          newsize = this%struct_vector_1d(j)%size * reallocate_mult
+          newsize = this%struct_vectors(j)%size * reallocate_mult
           !
           allocate (p_dbl1d(newsize))
           !
-          do i = 1, this%struct_vector_1d(j)%size
-            p_dbl1d(i) = this%struct_vector_1d(j)%dbl1d(i)
+          do i = 1, this%struct_vectors(j)%size
+            p_dbl1d(i) = this%struct_vectors(j)%dbl1d(i)
           end do
           !
-          deallocate (this%struct_vector_1d(j)%dbl1d)
+          deallocate (this%struct_vectors(j)%dbl1d)
           !
-          this%struct_vector_1d(j)%dbl1d => p_dbl1d
-          this%struct_vector_1d(j)%size = newsize
+          this%struct_vectors(j)%dbl1d => p_dbl1d
+          this%struct_vectors(j)%size = newsize
         end if
         !
       case (3) ! -- memtype charstring
-        if (this%nrow > this%struct_vector_1d(j)%size) then
+        if (this%nrow > this%struct_vectors(j)%size) then
           !
-          newsize = this%struct_vector_1d(j)%size * reallocate_mult
+          newsize = this%struct_vectors(j)%size * reallocate_mult
           !
           allocate (p_charstr1d(newsize))
           !
-          do i = 1, this%struct_vector_1d(j)%size
-            p_charstr1d(i) = this%struct_vector_1d(j)%charstr1d(i)
+          do i = 1, this%struct_vectors(j)%size
+            p_charstr1d(i) = this%struct_vectors(j)%charstr1d(i)
           end do
           !
-          deallocate (this%struct_vector_1d(j)%charstr1d)
+          deallocate (this%struct_vectors(j)%charstr1d)
           !
-          this%struct_vector_1d(j)%charstr1d => p_charstr1d
-          this%struct_vector_1d(j)%size = newsize
+          this%struct_vectors(j)%charstr1d => p_charstr1d
+          this%struct_vectors(j)%size = newsize
         end if
+      case (5)
+        if (this%nrow > this%struct_vectors(j)%size) then
+          !
+          newsize = this%struct_vectors(j)%size * reallocate_mult
+          !
+          allocate (p_int2d(this%struct_vectors(j)%intshape, newsize))
+          !
+          do i = 1, this%struct_vectors(j)%size
+            do k = 1, this%struct_vectors(j)%intshape
+              p_int2d(k, i) = this%struct_vectors(j)%int2d(k, i)
+            end do
+          end do
+          !
+          deallocate (this%struct_vectors(j)%int2d)
+          !
+          this%struct_vectors(j)%int2d => p_int2d
+          this%struct_vectors(j)%size = newsize
+        end if
+        !TODO: case (6)
       case default
+        errmsg = 'Programming error. IDM check_reallocate unsupported memtype.'
+        call store_error(errmsg, terminate=.TRUE.)
       end select
     end do
     !
@@ -578,12 +746,14 @@ end subroutine check_reallocate
 
   !> @brief read from the block parser to fill the StructArrayType
   !<
-  subroutine read_from_parser(this, parser, iout)
+  function read_from_parser(this, parser, timeseries, iout) result(irow)
     class(StructArrayType) :: this !< StructArrayType
     type(BlockParserType) :: parser !< block parser to read from
+    logical(LGP), intent(in) :: timeseries
     integer(I4B), intent(in) :: iout !< unit number for output
-    logical(LGP) :: endOfBlock
-    integer(I4B) :: irow, j, k
+    integer(I4B) :: irow
+    logical(LGP) :: endOfBlock, preserve_case
+    integer(I4B) :: j, k
     integer(I4B) :: intval, numval
     character(len=LINELENGTH) :: str
     character(len=:), allocatable :: line
@@ -616,51 +786,79 @@ subroutine read_from_parser(this, parser, iout)
       ! -- handle line reads by column memtype
       do j = 1, this%ncol
         !
-        select case (this%struct_vector_1d(j)%memtype)
+        select case (this%struct_vectors(j)%memtype)
           !
         case (1) ! -- memtype integer
           !
           ! -- if reloadable block and first col, store blocknum
           if (j == 1 .and. this%blocknum > 0) then
             ! -- store blocknum
-            this%struct_vector_1d(j)%int1d(irow) = this%blocknum
+            this%struct_vectors(j)%int1d(irow) = this%blocknum
           else
             ! -- read and store int
-            this%struct_vector_1d(j)%int1d(irow) = parser%GetInteger()
+            this%struct_vectors(j)%int1d(irow) = parser%GetInteger()
           end if
           !
         case (2) ! -- memtype real
           !
-          this%struct_vector_1d(j)%dbl1d(irow) = parser%GetDouble()
+          if (this%struct_vectors(j)%idt%timeseries .and. timeseries) then
+            call parser%GetString(str)
+            this%struct_vectors(j)%dbl1d(irow) = &
+              this%struct_vectors(j)%read_token(str, this%startidx(j), 1, irow)
+          else
+            this%struct_vectors(j)%dbl1d(irow) = parser%GetDouble()
+          end if
           !
         case (3) ! -- memtype charstring
           !
-          !if (this%struct_vector_1d(j)%shapevar == ':') then
-          if (this%struct_vector_1d(j)%shapevar /= '') then
+          !if (this%struct_vectors(j)%idt%shape == ':') then
+          if (this%struct_vectors(j)%idt%shape /= '') then
             ! -- if last column with any shape, store rest of line
             if (j == this%ncol) then
               call parser%GetRemainingLine(line)
-              this%struct_vector_1d(j)%charstr1d(irow) = line
+              this%struct_vectors(j)%charstr1d(irow) = line
               deallocate (line)
             end if
           else
             !
             ! -- read string token
-            call parser%GetString(str, &
-                                  (.not. this%struct_vector_1d(j)%preserve_case))
-            this%struct_vector_1d(j)%charstr1d(irow) = str
+            preserve_case = (.not. this%struct_vectors(j)%idt%preserve_case)
+            call parser%GetString(str, preserve_case)
+            this%struct_vectors(j)%charstr1d(irow) = str
           end if
           !
         case (4) ! -- memtype intvector
           !
           ! -- get shape for this row
-          numval = this%struct_vector_1d(j)%intvector_shape(irow)
+          numval = this%struct_vectors(j)%intvector_shape(irow)
           !
           ! -- read and store row values
           do k = 1, numval
             intval = parser%GetInteger()
-            call this%struct_vector_1d(j)%intvector%push_back(intval)
+            call this%struct_vectors(j)%intvector%push_back(intval)
           end do
+          !
+        case (5) ! -- memtype int2d
+          !
+          ! -- read and store row values
+          do k = 1, this%struct_vectors(j)%intshape
+            this%struct_vectors(j)%int2d(k, irow) = parser%GetInteger()
+          end do
+          !
+        case (6) ! -- memtype dbl2d
+          !
+          ! -- read and store row values
+          do k = 1, this%struct_vectors(j)%intshape
+            if (this%struct_vectors(j)%idt%timeseries .and. timeseries) then
+              call parser%GetString(str)
+              this%struct_vectors(j)%dbl2d(k, irow) = &
+                this%struct_vectors(j)%read_token(str, this%startidx(j) + k - 1, &
+                                                  k, irow)
+            else
+              this%struct_vectors(j)%dbl2d(k, irow) = parser%GetDouble()
+            end if
+          end do
+          !
         end select
       end do
     end do
@@ -669,8 +867,132 @@ subroutine read_from_parser(this, parser, iout)
     call this%memload_vectors()
     !
     ! -- log loaded variables
-    call this%log_structarray_vars(iout)
+    if (iout > 0) then
+      call this%log_structarray_vars(iout)
+    end if
+    !
+    ! -- return
+    return
+  end function read_from_parser
 
-  end subroutine read_from_parser
+  !> @brief read from binary input to fill the StructArrayType
+  !<
+  function read_from_binary(this, inunit, iout) result(irow)
+    class(StructArrayType) :: this !< StructArrayType
+    integer(I4B), intent(in) :: inunit !< unit number for binary input
+    integer(I4B), intent(in) :: iout !< unit number for output
+    integer(I4B) :: irow, ierr
+    integer(I4B) :: j, k
+    integer(I4B) :: intval, numval
+    character(len=LINELENGTH) :: fname
+    character(len=*), parameter :: fmtlsterronly = &
+      "('Error reading LIST from file: ',&
+      &1x,a,1x,' on UNIT: ',I0)"
+    !
+    ! -- set error and exit if deferred shape
+    if (this%deferred_shape) then
+      !
+      errmsg = 'Programming error. IDM SA deferred shape currently not &
+               &supported for binary inputs.'
+      call store_error(errmsg, terminate=.TRUE.)
+      !
+    end if
+    !
+    ! -- initialize
+    irow = 0
+    ierr = 0
+    !
+    readloop: do
+      !
+      ! -- update irow index
+      irow = irow + 1
+      !
+      ! -- handle line reads by column memtype
+      do j = 1, this%ncol
+        !
+        select case (this%struct_vectors(j)%memtype)
+          !
+        case (1) ! -- memtype integer
+          read (inunit, iostat=ierr) this%struct_vectors(j)%int1d(irow)
+        case (2) ! -- memtype real
+          read (inunit, iostat=ierr) this%struct_vectors(j)%dbl1d(irow)
+        case (3) ! -- memtype charstring
+          !
+          errmsg = 'Programming error. IDM SA input string types currently not &
+                   &supported for binary inputs.'
+          call store_error(errmsg, terminate=.TRUE.)
+          !
+        case (4) ! -- memtype intvector
+          !
+          ! -- get shape for this row
+          numval = this%struct_vectors(j)%intvector_shape(irow)
+          !
+          ! -- read and store row values
+          do k = 1, numval
+            if (ierr == 0) then
+              read (inunit, iostat=ierr) intval
+              call this%struct_vectors(j)%intvector%push_back(intval)
+            end if
+          end do
+          !
+        case (5) ! -- memtype int2d
+          !
+          ! -- read and store row values
+          do k = 1, this%struct_vectors(j)%intshape
+            if (ierr == 0) then
+              read (inunit, iostat=ierr) this%struct_vectors(j)%int2d(k, irow)
+            end if
+          end do
+          !
+        case (6) ! -- memtype dbl2d
+          do k = 1, this%struct_vectors(j)%intshape
+            if (ierr == 0) then
+              read (inunit, iostat=ierr) this%struct_vectors(j)%dbl2d(k, irow)
+            end if
+          end do
+        end select
+        !
+        ! -- handle error cases
+        select case (ierr)
+        case (0)
+          ! no error
+        case (:-1)
+          !
+          ! -- End of block was encountered
+          irow = irow - 1
+          exit readloop
+          !
+        case (1:)
+          !
+          ! -- Error
+          inquire (unit=inunit, name=fname)
+          write (errmsg, fmtlsterronly) trim(adjustl(fname)), inunit
+          call store_error(errmsg, terminate=.TRUE.)
+          !
+        case default
+        end select
+        !
+      end do
+      !
+      if (irow == this%nrow) exit readloop
+      !
+    end do readloop
+    !
+    ! -- Stop if errors were detected
+    !if (count_errors() > 0) then
+    !  call store_error_unit(inunit)
+    !end if
+    !
+    ! -- if deferred shape vectors were read, load to input path
+    call this%memload_vectors()
+    !
+    ! -- log loaded variables
+    if (iout > 0) then
+      call this%log_structarray_vars(iout)
+    end if
+    !
+    ! -- return
+    return
+  end function read_from_binary
 
 end module StructArrayModule
diff --git a/src/Utilities/Idm/mf6blockfile/StructVector.f90 b/src/Utilities/Idm/mf6blockfile/StructVector.f90
index a6c0223b2b7..d9618d4fba9 100644
--- a/src/Utilities/Idm/mf6blockfile/StructVector.f90
+++ b/src/Utilities/Idm/mf6blockfile/StructVector.f90
@@ -7,13 +7,27 @@
 module StructVectorModule
 
   use KindModule, only: I4B, DP, LGP
-  use ConstantsModule, only: LENMEMPATH, LENVARNAME
+  use ConstantsModule, only: DNODATA, LENMEMPATH, LENVARNAME, LINELENGTH, &
+                             LENTIMESERIESNAME
+  use ListModule, only: ListType
+  use InputDefinitionModule, only: InputParamDefinitionType
   use CharacterStringModule, only: CharacterStringType
   use STLVecIntModule, only: STLVecInt
+  use ArrayHandlersModule, only: expandarray
 
   implicit none
   private
-  public :: StructVectorType
+  public :: StructVectorType, TSStringLocType
+
+  !> @brief derived type which describes time series string field
+  !<
+  type :: TSStringLocType
+    integer(I4B) :: structarray_col !< global SA column index
+    integer(I4B) :: col !< SV column (1 if 1d array)
+    integer(I4B) :: row !< SV row
+    character(LINELENGTH) :: token !< TS string token
+  contains
+  end type TSStringLocType
 
   !> @brief derived type for generic vector
   !!
@@ -22,20 +36,127 @@ module StructVectorModule
   !!
   !<
   type StructVectorType
-    character(len=LENVARNAME) :: varname
-    character(len=100) :: tagname
-    character(len=LENVARNAME) :: shapevar
-    character(len=LENMEMPATH) :: mempath
-    integer(I4B) :: memtype = 0
-    integer(I4B) :: size = 0
-    logical(LGP) :: preserve_case = .false.
+    type(InputParamDefinitionType), pointer :: idt !< input definition
+    ! SA vector attributes
+    integer(I4B) :: memtype = 0 !< SA memtype
+    integer(I4B) :: icol = 0 !< SA column
+    integer(I4B) :: size = 0 !< size of array
+    ! Data pointers
     integer(I4B), dimension(:), pointer, contiguous :: int1d => null()
+    integer(I4B), dimension(:, :), pointer, contiguous :: int2d => null()
     real(DP), dimension(:), pointer, contiguous :: dbl1d => null()
+    real(DP), dimension(:, :), pointer, contiguous :: dbl2d => null()
     type(CharacterStringType), dimension(:), pointer, contiguous :: &
       charstr1d => null()
     type(STLVecInt), pointer :: intvector => null()
+    ! Shape data pointers
+    integer(I4B), pointer :: intshape => null()
     integer(I4B), dimension(:), pointer, contiguous :: intvector_shape => null()
-
+    ! TimeSeries strings
+    type(ListType) :: ts_strlocs
+  contains
+    procedure :: clear => sv_clear
+    procedure :: read_token => sv_read_token
+    procedure :: add_ts_strloc => sv_add_ts_strloc
+    procedure :: get_ts_strloc => sv_get_ts_strloc
   end type StructVectorType
 
+contains
+
+  function sv_read_token(this, token, structarray_col, col, row) result(val)
+    ! -- modules
+    ! -- dummy
+    class(StructVectorType) :: this
+    character(len=*), intent(in) :: token
+    integer(I4B), intent(in) :: structarray_col
+    integer(I4B), intent(in) :: col
+    integer(I4B), intent(in) :: row
+    real(DP) :: val
+    ! -- local
+    integer(I4B) :: istat
+    real(DP) :: r
+    !
+    ! -- initialize
+    val = DNODATA
+    !
+    read (token, *, iostat=istat) r
+    if (istat == 0) then
+      val = r
+    else
+      call this%add_ts_strloc(token, structarray_col, col, row)
+    end if
+    !
+    ! -- return
+    return
+  end function sv_read_token
+
+  subroutine sv_add_ts_strloc(this, token, structarray_col, col, row)
+    ! -- dummy variables
+    class(StructVectorType) :: this
+    character(len=*), intent(in) :: token
+    integer(I4B), intent(in) :: structarray_col
+    integer(I4B), intent(in) :: col
+    integer(I4B), intent(in) :: row
+    class(TSStringLocType), pointer :: str_field
+    ! -- local variables
+    class(*), pointer :: obj
+    !
+    ! --
+    allocate (str_field)
+    str_field%structarray_col = structarray_col
+    str_field%col = col
+    str_field%row = row
+    str_field%token = token
+    !
+    obj => str_field
+    call this%ts_strlocs%Add(obj)
+    !
+    ! -- return
+    return
+  end subroutine sv_add_ts_strloc
+
+  function sv_get_ts_strloc(this, idx) result(res)
+    ! -- dummy variables
+    class(StructVectorType) :: this
+    integer(I4B), intent(in) :: idx !< package number
+    class(TSStringLocType), pointer :: res
+    ! -- local variables
+    class(*), pointer :: obj
+    !
+    ! -- initialize res
+    res => null()
+    !
+    ! -- get the package from the list
+    obj => this%ts_strlocs%GetItem(idx)
+    if (associated(obj)) then
+      select type (obj)
+      class is (TSStringLocType)
+        res => obj
+      end select
+    end if
+    !
+    ! -- return
+    return
+  end function sv_get_ts_strloc
+
+  !> @brief
+  !<
+  subroutine sv_clear(this)
+    ! -- modules
+    ! -- dummy
+    class(StructVectorType) :: this
+    class(TSStringLocType), pointer :: ts_strloc
+    integer(I4B) :: n
+    !
+    do n = 1, this%ts_strlocs%Count()
+      ts_strloc => this%get_ts_strloc(n)
+      deallocate (ts_strloc)
+      nullify (ts_strloc)
+    end do
+    !
+    call this%ts_strlocs%Clear()
+    !
+    return
+  end subroutine sv_clear
+
 end module StructVectorModule
diff --git a/src/Utilities/Idm/selector/IdmDfnSelector.f90 b/src/Utilities/Idm/selector/IdmDfnSelector.f90
index a3e13b0ead0..a7b6190f6ff 100644
--- a/src/Utilities/Idm/selector/IdmDfnSelector.f90
+++ b/src/Utilities/Idm/selector/IdmDfnSelector.f90
@@ -1,24 +1,14 @@
 ! ** Do Not Modify! MODFLOW 6 system generated file. **
 module IdmDfnSelectorModule
 
+  use ConstantsModule, only: LENVARNAME
   use SimModule, only: store_error
   use InputDefinitionModule, only: InputParamDefinitionType, &
                                    InputBlockDefinitionType
-  use IdmGwfDfnSelectorModule, only: gwf_param_definitions, &
-                                     gwf_aggregate_definitions, &
-                                     gwf_block_definitions, &
-                                     gwf_idm_multi_package, &
-                                     gwf_idm_integrated
-  use IdmGwtDfnSelectorModule, only: gwt_param_definitions, &
-                                     gwt_aggregate_definitions, &
-                                     gwt_block_definitions, &
-                                     gwt_idm_multi_package, &
-                                     gwt_idm_integrated
-  use IdmSimDfnSelectorModule, only: sim_param_definitions, &
-                                     sim_aggregate_definitions, &
-                                     sim_block_definitions, &
-                                     sim_idm_multi_package, &
-                                     sim_idm_integrated
+  use IdmGwfDfnSelectorModule
+  use IdmGwtDfnSelectorModule
+  use IdmExgDfnSelectorModule
+  use IdmSimDfnSelectorModule
 
   implicit none
   private
@@ -27,6 +17,7 @@ module IdmDfnSelectorModule
   public :: block_definitions
   public :: idm_multi_package
   public :: idm_integrated
+  public :: idm_component
 
 contains
 
@@ -40,6 +31,8 @@ function param_definitions(component, subcomponent) result(input_definition)
       input_definition => gwf_param_definitions(subcomponent)
     case ('GWT')
       input_definition => gwt_param_definitions(subcomponent)
+    case ('EXG')
+      input_definition => exg_param_definitions(subcomponent)
     case ('SIM')
       input_definition => sim_param_definitions(subcomponent)
     case default
@@ -57,6 +50,8 @@ function aggregate_definitions(component, subcomponent) result(input_definition)
       input_definition => gwf_aggregate_definitions(subcomponent)
     case ('GWT')
       input_definition => gwt_aggregate_definitions(subcomponent)
+    case ('EXG')
+      input_definition => exg_aggregate_definitions(subcomponent)
     case ('SIM')
       input_definition => sim_aggregate_definitions(subcomponent)
     case default
@@ -74,6 +69,8 @@ function block_definitions(component, subcomponent) result(input_definition)
       input_definition => gwf_block_definitions(subcomponent)
     case ('GWT')
       input_definition => gwt_block_definitions(subcomponent)
+    case ('EXG')
+      input_definition => exg_block_definitions(subcomponent)
     case ('SIM')
       input_definition => sim_block_definitions(subcomponent)
     case default
@@ -90,6 +87,8 @@ function idm_multi_package(component, subcomponent) result(multi_package)
       multi_package = gwf_idm_multi_package(subcomponent)
     case ('GWT')
       multi_package = gwt_idm_multi_package(subcomponent)
+    case ('EXG')
+      multi_package = exg_idm_multi_package(subcomponent)
     case ('SIM')
       multi_package = sim_idm_multi_package(subcomponent)
     case default
@@ -110,6 +109,8 @@ function idm_integrated(component, subcomponent) result(integrated)
       integrated = gwf_idm_integrated(subcomponent)
     case ('GWT')
       integrated = gwt_idm_integrated(subcomponent)
+    case ('EXG')
+      integrated = exg_idm_integrated(subcomponent)
     case ('SIM')
       integrated = sim_idm_integrated(subcomponent)
     case default
@@ -117,4 +118,22 @@ function idm_integrated(component, subcomponent) result(integrated)
     return
   end function idm_integrated
 
+  function idm_component(component) result(integrated)
+    character(len=*), intent(in) :: component
+    logical :: integrated
+    integrated = .false.
+    select case (component)
+    case ('GWF')
+      integrated = .true.
+    case ('GWT')
+      integrated = .true.
+    case ('EXG')
+      integrated = .true.
+    case ('SIM')
+      integrated = .true.
+    case default
+    end select
+    return
+  end function idm_component
+
 end module IdmDfnSelectorModule
diff --git a/src/Utilities/Idm/selector/IdmExgDfnSelector.f90 b/src/Utilities/Idm/selector/IdmExgDfnSelector.f90
new file mode 100644
index 00000000000..fa6aea90bc6
--- /dev/null
+++ b/src/Utilities/Idm/selector/IdmExgDfnSelector.f90
@@ -0,0 +1,116 @@
+! ** Do Not Modify! MODFLOW 6 system generated file. **
+module IdmExgDfnSelectorModule
+
+  use ConstantsModule, only: LENVARNAME
+  use SimModule, only: store_error
+  use InputDefinitionModule, only: InputParamDefinitionType, &
+                                   InputBlockDefinitionType
+  use ExgGwfgwfInputModule
+  use ExgGwfgwtInputModule
+  use ExgGwtgwtInputModule
+
+  implicit none
+  private
+  public :: exg_param_definitions
+  public :: exg_aggregate_definitions
+  public :: exg_block_definitions
+  public :: exg_idm_multi_package
+  public :: exg_idm_integrated
+
+contains
+
+  subroutine set_param_pointer(input_dfn, input_dfn_target)
+    type(InputParamDefinitionType), dimension(:), pointer :: input_dfn
+    type(InputParamDefinitionType), dimension(:), target :: input_dfn_target
+    input_dfn => input_dfn_target
+  end subroutine set_param_pointer
+
+  subroutine set_block_pointer(input_dfn, input_dfn_target)
+    type(InputBlockDefinitionType), dimension(:), pointer :: input_dfn
+    type(InputBlockDefinitionType), dimension(:), target :: input_dfn_target
+    input_dfn => input_dfn_target
+  end subroutine set_block_pointer
+
+  function exg_param_definitions(subcomponent) result(input_definition)
+    character(len=*), intent(in) :: subcomponent
+    type(InputParamDefinitionType), dimension(:), pointer :: input_definition
+    nullify (input_definition)
+    select case (subcomponent)
+    case ('GWFGWF')
+      call set_param_pointer(input_definition, exg_gwfgwf_param_definitions)
+    case ('GWFGWT')
+      call set_param_pointer(input_definition, exg_gwfgwt_param_definitions)
+    case ('GWTGWT')
+      call set_param_pointer(input_definition, exg_gwtgwt_param_definitions)
+    case default
+    end select
+    return
+  end function exg_param_definitions
+
+  function exg_aggregate_definitions(subcomponent) result(input_definition)
+    character(len=*), intent(in) :: subcomponent
+    type(InputParamDefinitionType), dimension(:), pointer :: input_definition
+    nullify (input_definition)
+    select case (subcomponent)
+    case ('GWFGWF')
+      call set_param_pointer(input_definition, exg_gwfgwf_aggregate_definitions)
+    case ('GWFGWT')
+      call set_param_pointer(input_definition, exg_gwfgwt_aggregate_definitions)
+    case ('GWTGWT')
+      call set_param_pointer(input_definition, exg_gwtgwt_aggregate_definitions)
+    case default
+    end select
+    return
+  end function exg_aggregate_definitions
+
+  function exg_block_definitions(subcomponent) result(input_definition)
+    character(len=*), intent(in) :: subcomponent
+    type(InputBlockDefinitionType), dimension(:), pointer :: input_definition
+    nullify (input_definition)
+    select case (subcomponent)
+    case ('GWFGWF')
+      call set_block_pointer(input_definition, exg_gwfgwf_block_definitions)
+    case ('GWFGWT')
+      call set_block_pointer(input_definition, exg_gwfgwt_block_definitions)
+    case ('GWTGWT')
+      call set_block_pointer(input_definition, exg_gwtgwt_block_definitions)
+    case default
+    end select
+    return
+  end function exg_block_definitions
+
+  function exg_idm_multi_package(subcomponent) result(multi_package)
+    character(len=*), intent(in) :: subcomponent
+    logical :: multi_package
+    select case (subcomponent)
+    case ('GWFGWF')
+      multi_package = exg_gwfgwf_multi_package
+    case ('GWFGWT')
+      multi_package = exg_gwfgwt_multi_package
+    case ('GWTGWT')
+      multi_package = exg_gwtgwt_multi_package
+    case default
+      call store_error('Idm selector subcomponent not found; '//&
+                       &'component="EXG"'//&
+                       &', subcomponent="'//trim(subcomponent)//'".', .true.)
+    end select
+    return
+  end function exg_idm_multi_package
+
+  function exg_idm_integrated(subcomponent) result(integrated)
+    character(len=*), intent(in) :: subcomponent
+    logical :: integrated
+    integrated = .false.
+    select case (subcomponent)
+    case ('GWFGWF')
+      integrated = .true.
+    case ('GWFGWT')
+      integrated = .true.
+    case ('GWTGWT')
+      integrated = .true.
+    case default
+    end select
+    return
+  end function exg_idm_integrated
+
+end module IdmExgDfnSelectorModule
diff --git a/src/Utilities/Idm/selector/IdmGwfDfnSelector.f90 b/src/Utilities/Idm/selector/IdmGwfDfnSelector.f90
index 4ff5996addd..7cfc9ccd101 100644
--- a/src/Utilities/Idm/selector/IdmGwfDfnSelector.f90
+++ b/src/Utilities/Idm/selector/IdmGwfDfnSelector.f90
@@ -1,29 +1,25 @@
 ! ** Do Not Modify! MODFLOW 6 system generated file. **
 module IdmGwfDfnSelectorModule
 
+  use ConstantsModule, only: LENVARNAME
   use SimModule, only: store_error
   use InputDefinitionModule, only: InputParamDefinitionType, &
                                    InputBlockDefinitionType
-  use GwfDisInputModule, only: gwf_dis_param_definitions, &
-                               gwf_dis_aggregate_definitions, &
-                               gwf_dis_block_definitions, &
-                               gwf_dis_multi_package
-  use GwfDisuInputModule, only: gwf_disu_param_definitions, &
-                                gwf_disu_aggregate_definitions, &
-                                gwf_disu_block_definitions, &
-                                gwf_disu_multi_package
-  use GwfDisvInputModule, only: gwf_disv_param_definitions, &
-                                gwf_disv_aggregate_definitions, &
-                                gwf_disv_block_definitions, &
-                                gwf_disv_multi_package
-  use GwfNpfInputModule, only: gwf_npf_param_definitions, &
-                               gwf_npf_aggregate_definitions, &
-                               gwf_npf_block_definitions, &
-                               gwf_npf_multi_package
-  use GwfNamInputModule, only: gwf_nam_param_definitions, &
-                               gwf_nam_aggregate_definitions, &
-                               gwf_nam_block_definitions, &
-                               gwf_nam_multi_package
+  use GwfChdInputModule
+  use GwfDisInputModule
+  use GwfDisuInputModule
+  use GwfDisvInputModule
+  use GwfDrnInputModule
+  use GwfEvtInputModule
+  use GwfEvtaInputModule
+  use GwfGhbInputModule
+  use GwfIcInputModule
+  use GwfNpfInputModule
+  use GwfRchInputModule
+  use GwfRchaInputModule
+  use GwfRivInputModule
+  use GwfWelInputModule
+  use GwfNamInputModule
 
   implicit none
   private
@@ -52,14 +48,34 @@ function gwf_param_definitions(subcomponent) result(input_definition)
     type(InputParamDefinitionType), dimension(:), pointer :: input_definition
     nullify (input_definition)
     select case (subcomponent)
+    case ('CHD')
+      call set_param_pointer(input_definition, gwf_chd_param_definitions)
     case ('DIS')
       call set_param_pointer(input_definition, gwf_dis_param_definitions)
     case ('DISU')
       call set_param_pointer(input_definition, gwf_disu_param_definitions)
     case ('DISV')
       call set_param_pointer(input_definition, gwf_disv_param_definitions)
+    case ('DRN')
+      call set_param_pointer(input_definition, gwf_drn_param_definitions)
+    case ('EVT')
+      call set_param_pointer(input_definition, gwf_evt_param_definitions)
+    case ('EVTA')
+      call set_param_pointer(input_definition, gwf_evta_param_definitions)
+    case ('GHB')
+      call set_param_pointer(input_definition, gwf_ghb_param_definitions)
+    case ('IC')
+      call set_param_pointer(input_definition, gwf_ic_param_definitions)
     case ('NPF')
       call set_param_pointer(input_definition, gwf_npf_param_definitions)
+    case ('RCH')
+      call set_param_pointer(input_definition, gwf_rch_param_definitions)
+    case ('RCHA')
+      call set_param_pointer(input_definition, gwf_rcha_param_definitions)
+    case ('RIV')
+      call set_param_pointer(input_definition, gwf_riv_param_definitions)
+    case ('WEL')
+      call set_param_pointer(input_definition, gwf_wel_param_definitions)
     case ('NAM')
       call set_param_pointer(input_definition, gwf_nam_param_definitions)
     case default
@@ -72,14 +88,34 @@ function gwf_aggregate_definitions(subcomponent) result(input_definition)
     type(InputParamDefinitionType), dimension(:), pointer :: input_definition
     nullify (input_definition)
     select case (subcomponent)
+    case ('CHD')
+      call set_param_pointer(input_definition, gwf_chd_aggregate_definitions)
     case ('DIS')
       call set_param_pointer(input_definition, gwf_dis_aggregate_definitions)
     case ('DISU')
       call set_param_pointer(input_definition, gwf_disu_aggregate_definitions)
     case ('DISV')
       call set_param_pointer(input_definition, gwf_disv_aggregate_definitions)
+    case ('DRN')
+      call set_param_pointer(input_definition, gwf_drn_aggregate_definitions)
+    case ('EVT')
+      call set_param_pointer(input_definition, gwf_evt_aggregate_definitions)
+    case ('EVTA')
+      call set_param_pointer(input_definition, gwf_evta_aggregate_definitions)
+    case ('GHB')
+      call set_param_pointer(input_definition, gwf_ghb_aggregate_definitions)
+    case ('IC')
+      call set_param_pointer(input_definition, gwf_ic_aggregate_definitions)
     case ('NPF')
       call set_param_pointer(input_definition, gwf_npf_aggregate_definitions)
+    case ('RCH')
+      call set_param_pointer(input_definition, gwf_rch_aggregate_definitions)
+    case ('RCHA')
+      call set_param_pointer(input_definition, gwf_rcha_aggregate_definitions)
+    case ('RIV')
+      call set_param_pointer(input_definition, gwf_riv_aggregate_definitions)
+    case ('WEL')
+      call set_param_pointer(input_definition, gwf_wel_aggregate_definitions)
     case ('NAM')
       call set_param_pointer(input_definition, gwf_nam_aggregate_definitions)
     case default
@@ -92,14 +128,34 @@ function gwf_block_definitions(subcomponent) result(input_definition)
     type(InputBlockDefinitionType), dimension(:), pointer :: input_definition
     nullify (input_definition)
     select case (subcomponent)
+    case ('CHD')
+      call set_block_pointer(input_definition, gwf_chd_block_definitions)
     case ('DIS')
       call set_block_pointer(input_definition, gwf_dis_block_definitions)
     case ('DISU')
       call set_block_pointer(input_definition, gwf_disu_block_definitions)
     case ('DISV')
       call set_block_pointer(input_definition, gwf_disv_block_definitions)
+    case ('DRN')
+      call set_block_pointer(input_definition, gwf_drn_block_definitions)
+    case ('EVT')
+      call set_block_pointer(input_definition, gwf_evt_block_definitions)
+    case ('EVTA')
+      call set_block_pointer(input_definition, gwf_evta_block_definitions)
+    case ('GHB')
+      call set_block_pointer(input_definition, gwf_ghb_block_definitions)
+    case ('IC')
+      call set_block_pointer(input_definition, gwf_ic_block_definitions)
     case ('NPF')
       call set_block_pointer(input_definition, gwf_npf_block_definitions)
+    case ('RCH')
+      call set_block_pointer(input_definition, gwf_rch_block_definitions)
+    case ('RCHA')
+      call set_block_pointer(input_definition, gwf_rcha_block_definitions)
+    case ('RIV')
+      call set_block_pointer(input_definition, gwf_riv_block_definitions)
+    case ('WEL')
+      call set_block_pointer(input_definition, gwf_wel_block_definitions)
     case ('NAM')
       call set_block_pointer(input_definition, gwf_nam_block_definitions)
     case default
@@ -111,14 +167,34 @@ function gwf_idm_multi_package(subcomponent) result(multi_package)
     character(len=*), intent(in) :: subcomponent
     logical :: multi_package
     select case (subcomponent)
+    case ('CHD')
+      multi_package = gwf_chd_multi_package
     case ('DIS')
       multi_package = gwf_dis_multi_package
     case ('DISU')
       multi_package = gwf_disu_multi_package
     case ('DISV')
       multi_package = gwf_disv_multi_package
+    case ('DRN')
+      multi_package = gwf_drn_multi_package
+    case ('EVT')
+      multi_package = gwf_evt_multi_package
+    case ('EVTA')
+      multi_package = gwf_evta_multi_package
+    case ('GHB')
+      multi_package = gwf_ghb_multi_package
+    case ('IC')
+      multi_package = gwf_ic_multi_package
     case ('NPF')
       multi_package = gwf_npf_multi_package
+    case ('RCH')
+      multi_package = gwf_rch_multi_package
+    case ('RCHA')
+      multi_package = gwf_rcha_multi_package
+    case ('RIV')
+      multi_package = gwf_riv_multi_package
+    case ('WEL')
+      multi_package = gwf_wel_multi_package
     case ('NAM')
       multi_package = gwf_nam_multi_package
     case default
@@ -134,14 +210,34 @@ function gwf_idm_integrated(subcomponent) result(integrated)
     logical :: integrated
     integrated = .false.
     select case (subcomponent)
+    case ('CHD')
+      integrated = .true.
     case ('DIS')
       integrated = .true.
     case ('DISU')
       integrated = .true.
     case ('DISV')
       integrated = .true.
+    case ('DRN')
+      integrated = .true.
+    case ('EVT')
+      integrated = .true.
+    case ('EVTA')
+      integrated = .true.
+    case ('GHB')
+      integrated = .true.
+    case ('IC')
+      integrated = .true.
     case ('NPF')
       integrated = .true.
+    case ('RCH')
+      integrated = .true.
+    case ('RCHA')
+      integrated = .true.
+    case ('RIV')
+      integrated = .true.
+    case ('WEL')
+      integrated = .true.
     case ('NAM')
       integrated = .true.
     case default
diff --git a/src/Utilities/Idm/selector/IdmGwtDfnSelector.f90 b/src/Utilities/Idm/selector/IdmGwtDfnSelector.f90
index 9c46a00b9b7..f9e71164ffa 100644
--- a/src/Utilities/Idm/selector/IdmGwtDfnSelector.f90
+++ b/src/Utilities/Idm/selector/IdmGwtDfnSelector.f90
@@ -1,29 +1,17 @@
 ! ** Do Not Modify! MODFLOW 6 system generated file. **
 module IdmGwtDfnSelectorModule
 
+  use ConstantsModule, only: LENVARNAME
   use SimModule, only: store_error
   use InputDefinitionModule, only: InputParamDefinitionType, &
                                    InputBlockDefinitionType
-  use GwtDisInputModule, only: gwt_dis_param_definitions, &
-                               gwt_dis_aggregate_definitions, &
-                               gwt_dis_block_definitions, &
-                               gwt_dis_multi_package
-  use GwtDisuInputModule, only: gwt_disu_param_definitions, &
-                                gwt_disu_aggregate_definitions, &
-                                gwt_disu_block_definitions, &
-                                gwt_disu_multi_package
-  use GwtDisvInputModule, only: gwt_disv_param_definitions, &
-                                gwt_disv_aggregate_definitions, &
-                                gwt_disv_block_definitions, &
-                                gwt_disv_multi_package
-  use GwtDspInputModule, only: gwt_dsp_param_definitions, &
-                               gwt_dsp_aggregate_definitions, &
-                               gwt_dsp_block_definitions, &
-                               gwt_dsp_multi_package
-  use GwtNamInputModule, only: gwt_nam_param_definitions, &
-                               gwt_nam_aggregate_definitions, &
-                               gwt_nam_block_definitions, &
-                               gwt_nam_multi_package
+  use GwtDisInputModule
+  use GwtDisuInputModule
+  use GwtDisvInputModule
+  use GwtDspInputModule
+  use GwtCncInputModule
+  use GwtIcInputModule
+  use GwtNamInputModule
 
   implicit none
   private
@@ -60,6 +48,10 @@ function gwt_param_definitions(subcomponent) result(input_definition)
       call set_param_pointer(input_definition, gwt_disv_param_definitions)
     case ('DSP')
       call set_param_pointer(input_definition, gwt_dsp_param_definitions)
+    case ('CNC')
+      call set_param_pointer(input_definition, gwt_cnc_param_definitions)
+    case ('IC')
+      call set_param_pointer(input_definition, gwt_ic_param_definitions)
     case ('NAM')
       call set_param_pointer(input_definition, gwt_nam_param_definitions)
     case default
@@ -80,6 +72,10 @@ function gwt_aggregate_definitions(subcomponent) result(input_definition)
       call set_param_pointer(input_definition, gwt_disv_aggregate_definitions)
     case ('DSP')
       call set_param_pointer(input_definition, gwt_dsp_aggregate_definitions)
+    case ('CNC')
+      call set_param_pointer(input_definition, gwt_cnc_aggregate_definitions)
+    case ('IC')
+      call set_param_pointer(input_definition, gwt_ic_aggregate_definitions)
     case ('NAM')
       call set_param_pointer(input_definition, gwt_nam_aggregate_definitions)
     case default
@@ -100,6 +96,10 @@ function gwt_block_definitions(subcomponent) result(input_definition)
       call set_block_pointer(input_definition, gwt_disv_block_definitions)
     case ('DSP')
       call set_block_pointer(input_definition, gwt_dsp_block_definitions)
+    case ('CNC')
+      call set_block_pointer(input_definition, gwt_cnc_block_definitions)
+    case ('IC')
+      call set_block_pointer(input_definition, gwt_ic_block_definitions)
     case ('NAM')
       call set_block_pointer(input_definition, gwt_nam_block_definitions)
     case default
@@ -119,6 +119,10 @@ function gwt_idm_multi_package(subcomponent) result(multi_package)
       multi_package = gwt_disv_multi_package
     case ('DSP')
       multi_package = gwt_dsp_multi_package
+    case ('CNC')
+      multi_package = gwt_cnc_multi_package
+    case ('IC')
+      multi_package = gwt_ic_multi_package
     case ('NAM')
       multi_package = gwt_nam_multi_package
     case default
@@ -142,6 +146,10 @@ function gwt_idm_integrated(subcomponent) result(integrated)
       integrated = .true.
     case ('DSP')
       integrated = .true.
+    case ('CNC')
+      integrated = .true.
+    case ('IC')
+      integrated = .true.
     case ('NAM')
       integrated = .true.
     case default
diff --git a/src/Utilities/Idm/selector/IdmSimDfnSelector.f90 b/src/Utilities/Idm/selector/IdmSimDfnSelector.f90
index dc216101720..bf18e39f182 100644
--- a/src/Utilities/Idm/selector/IdmSimDfnSelector.f90
+++ b/src/Utilities/Idm/selector/IdmSimDfnSelector.f90
@@ -1,13 +1,11 @@
 ! ** Do Not Modify! MODFLOW 6 system generated file. **
 module IdmSimDfnSelectorModule
 
+  use ConstantsModule, only: LENVARNAME
   use SimModule, only: store_error
   use InputDefinitionModule, only: InputParamDefinitionType, &
                                    InputBlockDefinitionType
-  use SimNamInputModule, only: sim_nam_param_definitions, &
-                               sim_nam_aggregate_definitions, &
-                               sim_nam_block_definitions, &
-                               sim_nam_multi_package
+  use SimNamInputModule
 
   implicit none
   private
diff --git a/src/Utilities/InputOutput.f90 b/src/Utilities/InputOutput.f90
index 8d12c1bd21b..4c3094299c5 100644
--- a/src/Utilities/InputOutput.f90
+++ b/src/Utilities/InputOutput.f90
@@ -5,49 +5,41 @@ module InputOutputModule
   use KindModule, only: DP, I4B, I8B
   use SimVariablesModule, only: iunext, isim_mode, errmsg
   use SimModule, only: store_error, store_error_unit
-  use ConstantsModule, only: IUSTART, IULAST,                                  &
-                             LINELENGTH, LENBIGLINE, LENBOUNDNAME,             &
-                             NAMEDBOUNDFLAG, MAXCHARLEN,                       &
-                             TABLEFT, TABCENTER, TABRIGHT,                     &
-                             TABSTRING, TABUCSTRING, TABINTEGER, TABREAL,      &
-                             DZERO
-  use GenericUtilitiesModule, only: is_same, sim_message
+  use ConstantsModule, only: IUSTART, IULAST, LINELENGTH, LENBIGLINE, &
+                             LENBOUNDNAME, NAMEDBOUNDFLAG, MAXCHARLEN, &
+                             TABLEFT, TABCENTER, TABRIGHT, TABSTRING, &
+                             TABUCSTRING, TABINTEGER, TABREAL, DZERO
+  use MessageModule, only: write_message
   private
-  public :: GetUnit, uget_block,                                               &
-            uterminate_block, UPCASE, URWORD, ULSTLB, UBDSV4,                  &
-            ubdsv06, UBDSVB, UCOLNO, ULAPRW,                                   &
-            ULASAV, ubdsv1, ubdsvc, ubdsvd, UWWORD,                            &
-            same_word, get_node, get_ijk, unitinquire,                         &
-            ParseLine, ulaprufw, openfile,                                     &
-            linear_interpolate, lowcase,                                       &
-            read_line, uget_any_block,                                         &
-            GetFileFromPath, extract_idnum_or_bndname, urdaux,                 &
-            get_jk, print_format, BuildFixedFormat,                            &
-            BuildFloatFormat, BuildIntFormat, fseek_stream,                    &
-            get_nwords, u9rdcom
+  public :: GetUnit, UPCASE, URWORD, ULSTLB, UBDSV4, ubdsv06, UBDSVB, UCOLNO, &
+            ULAPRW, ULASAV, ubdsv1, ubdsvc, ubdsvd, UWWORD, same_word, &
+            str_pad_left, unitinquire, ParseLine, ulaprufw, openfile, &
+            linear_interpolate, lowcase, read_line, GetFileFromPath, &
+            extract_idnum_or_bndname, urdaux, print_format, BuildFixedFormat, &
+            BuildFloatFormat, BuildIntFormat, fseek_stream, get_nwords, &
+            u9rdcom, append_processor_id
 
-  contains
+contains
 
   !> @brief Open a file
   !!
   !! Subroutine to open a file using the specified arguments
-  !!
   !<
-  subroutine openfile(iu, iout, fname, ftype, fmtarg_opt, accarg_opt,          &
+  subroutine openfile(iu, iout, fname, ftype, fmtarg_opt, accarg_opt, &
                       filstat_opt, mode_opt)
     ! -- modules
     use OpenSpecModule, only: action
     implicit none
-    ! -- dummy variables
-    integer(I4B), intent(inout)       :: iu                 !< unit number
-    integer(I4B), intent(in)          :: iout               !< output unit number to write a message (iout=0 does not print)
-    character(len=*), intent(in) :: fname                   !< name of the file
-    character(len=*), intent(in) :: ftype                   !< file type (e.g. WEL)
-    character(len=*), intent(in), optional :: fmtarg_opt    !< file format, default is 'formatted'
-    character(len=*), intent(in), optional :: accarg_opt    !< file access, default is 'sequential'
-    character(len=*), intent(in), optional :: filstat_opt   !< file status, default is 'old'. Use 'REPLACE' for output file.
-    integer(I4B), intent(in), optional :: mode_opt          !< simulation mode that is evaluated to determine if the file should be opened
-    ! -- local variables
+    ! -- dummy
+    integer(I4B), intent(inout) :: iu !< unit number
+    integer(I4B), intent(in) :: iout !< output unit number to write a message (iout=0 does not print)
+    character(len=*), intent(in) :: fname !< name of the file
+    character(len=*), intent(in) :: ftype !< file type (e.g. WEL)
+    character(len=*), intent(in), optional :: fmtarg_opt !< file format, default is 'formatted'
+    character(len=*), intent(in), optional :: accarg_opt !< file access, default is 'sequential'
+    character(len=*), intent(in), optional :: filstat_opt !< file status, default is 'old'. Use 'REPLACE' for output file.
+    integer(I4B), intent(in), optional :: mode_opt !< simulation mode that is evaluated to determine if the file should be opened
+    ! -- local
     character(len=20) :: fmtarg
     character(len=20) :: accarg
     character(len=20) :: filstat
@@ -57,23 +49,23 @@ subroutine openfile(iu, iout, fname, ftype, fmtarg_opt, accarg_opt,          &
     integer(I4B) :: ivar
     integer(I4B) :: iuop
     ! -- formats
-50  FORMAT(1X,/1X,'OPENED ',A,/                                                &
-                 1X,'FILE TYPE:',A,'   UNIT ',I4,3X,'STATUS:',A,/              &
-                 1X,'FORMAT:',A,3X,'ACCESS:',A/                                &
-                 1X,'ACTION:',A/)
-60  FORMAT(1X,/1X,'DID NOT OPEN ',A,/)
+    character(len=*), parameter :: fmtmsg = &
+      "(1x,/1x,'OPENED ',a,/1x,'FILE TYPE:',a,'   UNIT ',I4,3x,'STATUS:',a,/ &
+      & 1x,'FORMAT:',a,3x,'ACCESS:',a/1x,'ACTION:',a/)"
+    character(len=*), parameter :: fmtmsg2 = &
+                                   "(1x,/1x,'DID NOT OPEN ',a,/)"
     !
-    ! -- process mode_opt
+    ! -- Process mode_opt
     if (present(mode_opt)) then
       imode = mode_opt
     else
       imode = isim_mode
     end if
     !
-    ! -- evaluate if the file should be opened
+    ! -- Evaluate if the file should be opened
     if (isim_mode < imode) then
-      if(iout > 0) then
-        write(iout, 60) trim(fname)
+      if (iout > 0) then
+        write (iout, fmtmsg2) trim(fname)
       end if
     else
       !
@@ -83,49 +75,49 @@ subroutine openfile(iu, iout, fname, ftype, fmtarg_opt, accarg_opt,          &
       filstat = 'OLD'
       !
       ! -- Override defaults
-      if(present(fmtarg_opt)) then
+      if (present(fmtarg_opt)) then
         fmtarg = fmtarg_opt
         call upcase(fmtarg)
-      endif
-      if(present(accarg_opt)) then
+      end if
+      if (present(accarg_opt)) then
         accarg = accarg_opt
         call upcase(accarg)
-      endif
-      if(present(filstat_opt)) then
+      end if
+      if (present(filstat_opt)) then
         filstat = filstat_opt
         call upcase(filstat)
-      endif
-      if(filstat == 'OLD') then
+      end if
+      if (filstat == 'OLD') then
         filact = action(1)
       else
         filact = action(2)
-      endif
+      end if
       !
       ! -- size of fname
       iflen = len_trim(fname)
       !
       ! -- Get a free unit number
-      if(iu <= 0) then
+      if (iu <= 0) then
         call freeunitnumber(iu)
-      endif
+      end if
       !
       ! -- Check to see if file is already open, if not then open the file
-      inquire(file=fname(1:iflen), number=iuop)
-      if(iuop > 0) then
+      inquire (file=fname(1:iflen), number=iuop)
+      if (iuop > 0) then
         ivar = -1
       else
-        open(unit=iu, file=fname(1:iflen), form=fmtarg, access=accarg,           &
-           status=filstat, action=filact, iostat=ivar)
-      endif
+        open (unit=iu, file=fname(1:iflen), form=fmtarg, access=accarg, &
+              status=filstat, action=filact, iostat=ivar)
+      end if
       !
       ! -- Check for an error
-      if(ivar /= 0) then
+      if (ivar /= 0) then
         write (errmsg, '(3a,1x,i0,a)') &
           'Could not open "', fname(1:iflen), '" on unit', iu, '.'
-        if(iuop > 0) then
+        if (iuop > 0) then
           write (errmsg, '(a,1x,a,1x,i0,a)') &
             trim(errmsg), 'File already open on unit', iuop, '.'
-        endif
+        end if
         write (errmsg, '(a,1x,a,1x,a,a)') &
           trim(errmsg), 'Specified file status', trim(filstat), '.'
         write (errmsg, '(a,1x,a,1x,a,a)') &
@@ -139,58 +131,53 @@ subroutine openfile(iu, iout, fname, ftype, fmtarg_opt, accarg_opt,          &
         write (errmsg, '(a,1x,a)') &
           trim(errmsg), 'STOP EXECUTION in subroutine openfile().'
         call store_error(errmsg, terminate=.TRUE.)
-      endif
+      end if
       !
       ! -- Write a message
-      if(iout > 0) then
-        write(iout, 50) fname(1:iflen),                                          &
-                       ftype, iu, filstat,                                       &
-                       fmtarg, accarg,                                           &
-                       filact
+      if (iout > 0) then
+        write (iout, fmtmsg) fname(1:iflen), ftype, iu, filstat, fmtarg, &
+          accarg, filact
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine openfile
 
   !> @brief Assign a free unopened unit number
   !!
   !! Subroutine to assign a free unopened unit number to the iu dummy argument
-  !!
   !<
   subroutine freeunitnumber(iu)
     ! -- modules
     implicit none
-    ! -- dummy variables
-    integer(I4B),intent(inout) :: iu  !< next free file unit number
-    ! -- local variables
+    ! -- dummy
+    integer(I4B), intent(inout) :: iu !< next free file unit number
+    ! -- local
     integer(I4B) :: i
     logical :: opened
     !
-    ! -- code
     do i = iunext, iulast
-      inquire(unit=i, opened=opened)
-      if(.not. opened) exit
-    enddo
+      inquire (unit=i, opened=opened)
+      if (.not. opened) exit
+    end do
     iu = i
     iunext = iu + 1
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine freeunitnumber
 
   !> @brief Get a free unit number
   !!
   !! Function to get a free unit number that hasn't been used
-  !!
   !<
   function getunit()
     ! -- modules
     implicit none
     ! -- return
-    integer(I4B) :: getunit  !< free unit number
-    ! -- local variables
+    integer(I4B) :: getunit !< free unit number
+    ! -- local
     integer(I4B) :: iunit
     !
     ! -- code
@@ -200,250 +187,16 @@ function getunit()
     ! -- Return
     return
   end function getunit
-  
-  !> @brief Find a block in a file
-  !!
-  !! Subroutine to read from a file until the tag (ctag) for a block is
-  !! is found. Return isfound with true, if found.
-  !!
-  !<
-  subroutine uget_block(iin, iout, ctag, ierr, isfound, lloc, line, iuext,     &
-                        blockRequired, supportopenclose)
-    implicit none
-    ! -- dummy variables
-    integer(I4B),         intent(in) :: iin                   !< file unit
-    integer(I4B),         intent(in) :: iout                  !< output listing file unit 
-    character (len=*),    intent(in) :: ctag                  !< block tag
-    integer(I4B),        intent(out) :: ierr                  !< error 
-    logical,           intent(inout) :: isfound               !< boolean indicating if the block was found
-    integer(I4B),      intent(inout) :: lloc                  !< position in line
-    character (len=:), allocatable, intent(inout) :: line     !< line
-    integer(I4B),      intent(inout) :: iuext                 !< external file unit number
-    logical, optional,    intent(in) :: blockRequired         !< boolean indicating if the block is required
-    logical, optional,    intent(in) :: supportopenclose      !< boolean indicating if the block supports open/close
-    ! -- local variables
-    integer(I4B) :: istart
-    integer(I4B) :: istop
-    integer(I4B) :: ival
-    integer(I4B) :: lloc2
-    real(DP) :: rval
-    character (len=:), allocatable :: line2
-    character(len=LINELENGTH) :: fname
-    character(len=MAXCHARLEN) :: ermsg
-    logical :: supportoc, blockRequiredLocal
-    !
-    ! -- code
-    if (present(blockRequired)) then
-      blockRequiredLocal = blockRequired
-    else
-      blockRequiredLocal = .true.
-    endif
-    supportoc = .false.
-    if (present(supportopenclose)) then
-      supportoc = supportopenclose
-    endif
-    iuext = iin
-    isfound = .false.
-    mainloop: do
-      lloc = 1
-      call u9rdcom(iin, iout, line, ierr)
-      if (ierr < 0) then
-        if (blockRequiredLocal) then
-          ermsg = 'Required block "' // trim(ctag) // &
-                  '" not found.  Found end of file instead.'
-          call store_error(ermsg)
-          call store_error_unit(iuext)
-        end if
-        ! block not found so exit
-        exit
-      end if
-      call urword(line, lloc, istart, istop, 1, ival, rval, iin, iout)
-      if (line(istart:istop) == 'BEGIN') then
-        call urword(line, lloc, istart, istop, 1, ival, rval, iin, iout)
-        if (line(istart:istop) == ctag) then
-          isfound = .true.
-          if (supportoc) then
-            ! Look for OPEN/CLOSE on 1st line after line starting with BEGIN
-            call u9rdcom(iin, iout, line2, ierr)
-            if (ierr < 0) exit
-            lloc2 = 1
-            call urword(line2, lloc2, istart, istop, 1, ival, rval, iin, iout)
-            if (line2(istart:istop) == 'OPEN/CLOSE') then
-              ! -- Get filename and preserve case
-              call urword(line2, lloc2, istart, istop, 0, ival, rval, iin, iout)
-              fname = line2(istart:istop)
-              ! If line contains '(BINARY)' or 'SFAC', handle this block elsewhere
-              chk: do
-                call urword(line2, lloc2, istart, istop, 1, ival, rval, iin, iout)
-                if (line2(istart:istop) == '') exit chk
-                if (line2(istart:istop) == '(BINARY)' .or. &
-                    line2(istart:istop) == 'SFAC') then
-                  backspace(iin)
-                  exit mainloop
-                end if
-              end do chk
-              iuext = GetUnit()
-              call openfile(iuext,iout,fname,'OPEN/CLOSE')
-            else
-              backspace(iin)
-            end if
-          end if
-        else
-          if (blockRequiredLocal) then
-            ermsg = 'Error: Required block "' // trim(ctag) // &
-                    '" not found. Found block "' // line(istart:istop) // &
-                    '" instead.'
-            call store_error(ermsg)
-            call store_error_unit(iuext)
-          else
-            backspace(iin)
-          endif
-        end if
-        exit mainloop
-      else if (line(istart:istop) == 'END') then
-        call urword(line, lloc, istart, istop, 1, ival, rval, iin, iout)
-        if (line(istart:istop) == ctag) then
-          ermsg = 'Error: Looking for BEGIN ' // trim(ctag) // &
-                  ' but found END ' // line(istart:istop) // &
-                  ' instead.'
-          call store_error(ermsg)
-          call store_error_unit(iuext)
-        endif
-      end if
-    end do mainloop
-    !
-    ! -- return
-    return
-  end subroutine uget_block
-
-  !> @brief Find the next block in a file
-  !!
-  !! Subroutine to read from a file until next block is found.
-  !! Return isfound with true, if found, and return the block name.
-  !!
-  !<
-  subroutine uget_any_block(iin,iout,isfound,lloc,line,ctagfound,iuext)
-    implicit none
-    ! -- dummy variables
-    integer(I4B), intent(in) :: iin                         !< file unit number
-    integer(I4B), intent(in) :: iout                        !< output listing file unit
-    logical, intent(inout) :: isfound                       !< boolean indicating if a block was found
-    integer(I4B), intent(inout) :: lloc                     !< position in line
-    character (len=:), allocatable, intent(inout) :: line   !< line
-    character(len=*), intent(out) :: ctagfound              !< block name
-    integer(I4B), intent(inout) :: iuext                    !< external file unit number
-    ! -- local variables
-    integer(I4B) :: ierr, istart, istop
-    integer(I4B) :: ival, lloc2
-    real(DP) :: rval
-    character(len=100) :: ermsg
-    character (len=:), allocatable :: line2
-    character(len=LINELENGTH) :: fname
-    !
-    ! -- code
-    isfound = .false.
-    ctagfound = ''
-    iuext = iin
-    do
-      lloc = 1
-      call u9rdcom(iin,iout,line,ierr)
-      if (ierr < 0) exit
-      call urword(line, lloc, istart, istop, 1, ival, rval, iin, iout)
-      if (line(istart:istop) == 'BEGIN') then
-        call urword(line, lloc, istart, istop, 1, ival, rval, iin, iout)
-        if (line(istart:istop) /= '') then
-          isfound = .true.
-          ctagfound = line(istart:istop)
-          call u9rdcom(iin,iout,line2,ierr)
-          if (ierr < 0) exit
-          lloc2 = 1
-          call urword(line2,lloc2,istart,istop,1,ival,rval,iout,iin)
-          if (line2(istart:istop) == 'OPEN/CLOSE') then
-            iuext = GetUnit()
-            call urword(line2,lloc2,istart,istop,0,ival,rval,iout,iin)
-            fname = line2(istart:istop)
-            call openfile(iuext,iout,fname,'OPEN/CLOSE')
-          else
-            backspace(iin)
-          endif
-        else
-          ermsg  = 'Block name missing in file.'
-          call store_error(ermsg)
-          call store_error_unit(iin)
-        end if
-        exit
-      end if
-    end do
-    return
-  end subroutine uget_any_block
-
-  !> @brief Evaluate if the end of a block has been found
-  !!
-  !! Subroutine to evaluate if the end of a block has been found. Abnormal 
-  !! termination if 'begin' is found or if 'end' encountered with 
-  !! incorrect tag.
-  !!
-  !<
-  subroutine uterminate_block(iin,iout,key,ctag,lloc,line,ierr,iuext)
-    implicit none
-    ! -- dummy variables
-    integer(I4B), intent(in) :: iin              !< file unit number
-    integer(I4B), intent(in) :: iout             !< output listing file unit number
-    character (len=*), intent(in) :: key         !< keyword in block
-    character (len=*), intent(in) :: ctag        !< block name
-    integer(I4B), intent(inout) :: lloc          !< position in line
-    character (len=*), intent(inout) :: line     !< line
-    integer(I4B), intent(inout) :: ierr          !< error
-    integer(I4B), intent(inout) :: iuext         !< external file unit number
-    ! -- local variables
-    character(len=LENBIGLINE) :: ermsg
-    integer(I4B) :: istart
-    integer(I4B) :: istop
-    integer(I4B) :: ival
-    real(DP) :: rval
-    ! -- format
-1   format('ERROR. "',A,'" DETECTED WITHOUT "',A,'". ','"END',1X,A, &
-      '" MUST BE USED TO END ',A,'.')
-2   format('ERROR. "',A,'" DETECTED BEFORE "END',1X,A,'". ','"END',1X,A, &
-        '" MUST BE USED TO END ',A,'.')
-    !
-    ! -- code
-    ierr = 1
-    select case(key)
-      case ('END')
-        call urword(line, lloc, istart, istop, 1, ival, rval, iout, iin)
-        if (line(istart:istop) /= ctag) then
-          write(ermsg, 1) trim(key), trim(ctag), trim(ctag), trim(ctag)
-          call store_error(ermsg)
-          call store_error_unit(iin)
-        else
-          ierr = 0
-          if (iuext /= iin) then
-            ! -- close external file
-            close(iuext)
-            iuext = iin
-          endif
-        end if
-      case ('BEGIN')
-        write(ermsg, 2) trim(key), trim(ctag), trim(ctag), trim(ctag)
-        call store_error(ermsg)
-        call store_error_unit(iin)
-    end select
-    !
-    ! -- return
-    return
-  end subroutine uterminate_block
 
   !> @brief Convert to upper case
   !!
   !! Subroutine to convert a character string to upper case.
-  !!
   !<
   subroutine upcase(word)
     implicit none
-    ! -- dummy variables  
-    character (len=*), intent(inout) :: word  !< word to convert to upper case
-    ! -- local variables
+    ! -- dummy
+    character(len=*), intent(inout) :: word !< word to convert to upper case
+    ! -- local
     integer(I4B) :: l
     integer(I4B) :: idiff
     integer(I4B) :: k
@@ -458,167 +211,197 @@ subroutine upcase(word)
         word(k:k) = char(ichar(word(k:k)) - idiff)
     end do
     !
-    ! -- return.
+    ! -- Return
     return
-    end subroutine upcase
+  end subroutine upcase
 
   !> @brief Convert to lower case
   !!
   !! Subroutine to convert a character string to lower case.
-  !!
   !<
   subroutine lowcase(word)
     implicit none
-    ! -- dummy variables
-    character(len=*) :: word  !< 
-    ! -- local variables
+    ! -- dummy
+    character(len=*) :: word
+    ! -- local
     integer(I4B) :: idiff, k, l
     !
-    ! -- compute the difference between lowercase and uppercase.
+    ! -- Compute the difference between lowercase and uppercase.
     l = len(word)
     idiff = ichar('a') - ichar('A')
     !
-    ! -- loop through the string and convert any uppercase characters.
+    ! -- Loop through the string and convert any uppercase characters.
     do k = 1, l
-      if(word(k:k) >= 'A' .and. word(k:k) <= 'Z') then
-        word(k:k)=char(ichar(word(k:k))+idiff)
-      endif
-    enddo
+      if (word(k:k) >= 'A' .and. word(k:k) <= 'Z') then
+        word(k:k) = char(ichar(word(k:k)) + idiff)
+      end if
+    end do
     !
-    ! -- return.
+    ! -- Return
     return
   end subroutine lowcase
 
-  !> @brief Create a formatted line
+  !> @brief Append processor id to a string
   !!
-  !! Subroutine to create a formatted line with specified alignment
-  !! and column separators. Like URWORD, UWWORD works with strings,
-  !! integers, and floats. Can pass an optional format statement,
-  !! alignment, and column separator.
+  !! Subroutine to append the processor id to a string before the file extension
+  !! (extension is the string after the last '.' in the string. If there is
+  !! no '.' in the string the processor id is appended to the end of the string.
+  !<
+  subroutine append_processor_id(name, proc_id)
+    ! -- dummy
+    character(len=LINELENGTH), intent(inout) :: name !< file name
+    integer(I4B), intent(in) :: proc_id !< processor id
+    ! -- local
+    character(len=LINELENGTH) :: name_local
+    character(len=LINELENGTH) :: name_processor
+    character(len=LINELENGTH) :: extension_local
+    integer(I4B) :: ipos0
+    integer(I4B) :: ipos1
+    !
+    name_local = name
+    call lowcase(name_local)
+    ipos0 = index(name_local, ".", back=.TRUE.)
+    ipos1 = len_trim(name)
+    if (ipos0 > 0) then
+      write (extension_local, '(a)') name(ipos0:ipos1)
+    else
+      ipos0 = ipos1
+      extension_local = ''
+    end if
+    write (name_processor, '(a,a,i0,a)') &
+      name(1:ipos0 - 1), '.p', proc_id, trim(adjustl(extension_local))
+    name = name_processor
+    !
+    ! -- Return
+    return
+  end subroutine append_processor_id
+
+  !> @brief Create a formatted line
   !!
+  !! Subroutine to create a formatted line with specified alignment and column
+  !! separators. Like URWORD, UWWORD works with strings, integers, and floats.
+  !! Can pass an optional format statement, alignment, and column separator.
   !<
-  subroutine UWWORD(LINE,ICOL,ILEN,NCODE,C,N,R,FMT,ALIGNMENT,SEP)
+  subroutine UWWORD(line, icol, ilen, ncode, c, n, r, fmt, alignment, sep)
     implicit none
-    ! -- dummy variables
-    character (len=*), intent(inout) :: LINE         !< line
-    integer(I4B), intent(inout) :: ICOL              !< column to write to line
-    integer(I4B), intent(in) :: ILEN                 !< current length of line
-    integer(I4B), intent(in) :: NCODE                !< code for data type to write
-    character (len=*), intent(in) :: C               !< character data type
-    integer(I4B), intent(in) :: N                    !< integer data type
-    real(DP), intent(in) :: R                        !< float data type
-    character (len=*), optional, intent(in) :: FMT   !< format statement
-    integer(I4B), optional, intent(in) :: ALIGNMENT  !< alignment specifier
-    character (len=*), optional, intent(in) :: SEP   !< column separator
-    ! -- local variables
-    character (len=16) :: cfmt
-    character (len=16) :: cffmt
-    character (len=ILEN) :: cval
+    ! -- dummy
+    character(len=*), intent(inout) :: line !< line
+    integer(I4B), intent(inout) :: icol !< column to write to line
+    integer(I4B), intent(in) :: ilen !< current length of line
+    integer(I4B), intent(in) :: ncode !< code for data type to write
+    character(len=*), intent(in) :: c !< character data type
+    integer(I4B), intent(in) :: n !< integer data type
+    real(DP), intent(in) :: r !< float data type
+    character(len=*), optional, intent(in) :: fmt !< format statement
+    integer(I4B), optional, intent(in) :: alignment !< alignment specifier
+    character(len=*), optional, intent(in) :: sep !< column separator
+    ! -- local
+    character(len=16) :: cfmt
+    character(len=16) :: cffmt
+    character(len=ILEN) :: cval
     integer(I4B) :: ialign
     integer(I4B) :: i
     integer(I4B) :: ispace
     integer(I4B) :: istop
     integer(I4B) :: ipad
     integer(I4B) :: ireal
-    ! -- code
     !
     ! -- initialize locals
     ipad = 0
     ireal = 0
     !
     ! -- process dummy variables
-    if (present(FMT)) then
-      CFMT = FMT
+    if (present(fmt)) then
+      cfmt = fmt
     else
-      select case(NCODE)
-        case(TABSTRING, TABUCSTRING)
-          write(cfmt, '(A,I0,A)') '(A', ILEN, ')'
-        case(TABINTEGER)
-          write(cfmt, '(A,I0,A)') '(I', ILEN, ')'
-        case(TABREAL)
-          ireal = 1
-          i = ILEN - 7
-          write(cfmt, '(A,I0,A,I0,A)') '(1PG', ILEN, '.', i, ')'
-          if (R >= DZERO) then
-            ipad = 1
-          end if
+      select case (ncode)
+      case (TABSTRING, TABUCSTRING)
+        write (cfmt, '(a,I0,a)') '(a', ilen, ')'
+      case (TABINTEGER)
+        write (cfmt, '(a,I0,a)') '(I', ilen, ')'
+      case (TABREAL)
+        ireal = 1
+        i = ilen - 7
+        write (cfmt, '(a,I0,a,I0,a)') '(1PG', ilen, '.', i, ')'
+        if (R >= DZERO) then
+          ipad = 1
+        end if
       end select
     end if
-    write(cffmt, '(A,I0,A)') '(A', ILEN, ')'
-
-    if (present(ALIGNMENT)) then
-      ialign = ALIGNMENT
+    write (cffmt, '(a,I0,a)') '(a', ilen, ')'
+    !
+    if (present(alignment)) then
+      ialign = alignment
     else
       ialign = TABRIGHT
     end if
     !
-    ! -- 
-    if (NCODE == TABSTRING .or. NCODE == TABUCSTRING) then
+    if (ncode == TABSTRING .or. ncode == TABUCSTRING) then
       cval = C
-      if (NCODE == TABUCSTRING) then
-        call UPCASE(cval)
+      if (ncode == TABUCSTRING) then
+        call UPcase(cval)
       end if
-    else if (NCODE == TABINTEGER) then
-      write(cval, cfmt) N
-    else if (NCODE == TABREAL) then
-      write(cval, cfmt) R
+    else if (ncode == TABINTEGER) then
+      write (cval, cfmt) n
+    else if (ncode == TABREAL) then
+      write (cval, cfmt) r
     end if
     !
-    ! -- apply alignment to cval
-    if (len_trim(adjustl(cval)) > ILEN) then
+    ! -- Apply alignment to cval
+    if (len_trim(adjustl(cval)) > ilen) then
       cval = adjustl(cval)
     else
       cval = trim(adjustl(cval))
     end if
     if (ialign == TABCENTER) then
       i = len_trim(cval)
-      ispace = (ILEN - i) / 2
+      ispace = (ilen - i) / 2
       if (ireal > 0) then
         if (ipad > 0) then
-          cval = ' ' //trim(adjustl(cval))
+          cval = ' '//trim(adjustl(cval))
         else
           cval = trim(adjustl(cval))
         end if
       else
-        cval = repeat(' ', ispace) // trim(cval)
+        cval = repeat(' ', ispace)//trim(cval)
       end if
     else if (ialign == TABLEFT) then
       cval = trim(adjustl(cval))
       if (ipad > 0) then
-        cval = ' ' //trim(adjustl(cval))
+        cval = ' '//trim(adjustl(cval))
       end if
     else
       cval = adjustr(cval)
     end if
-    if (NCODE == TABUCSTRING) then
-      call UPCASE(cval)
+    if (ncode == TABUCSTRING) then
+      call UPcase(cval)
     end if
     !
-    ! -- increment istop to the end of the column
-    istop = ICOL + ILEN - 1
+    ! -- Increment istop to the end of the column
+    istop = icol + ilen - 1
     !
-    ! -- write final string to line
-    write(LINE(ICOL:istop), cffmt) cval
-
-    ICOL = istop + 1
-
-    if (present(SEP)) then
-      i = len(SEP)
-      istop = ICOL + i
-      write(LINE(ICOL:istop), '(A)') SEP
-      ICOL = istop
+    ! -- Write final string to line
+    write (line(icol:istop), cffmt) cval
+    !
+    icoL = istop + 1
+    !
+    if (present(sep)) then
+      i = len(sep)
+      istop = icol + i
+      write (line(icol:istop), '(a)') sep
+      icol = istop
     end if
     !
-    !-- return
+    ! -- Return
     return
   end subroutine UWWORD
 
   !> @brief Extract a word from a string
   !!
   !! Subroutine to extract a word from a line of text, and optionally
-  !! convert the word to a number. The last character in the line is 
-  !! set to blank so that if any problems occur with finding a word, 
-  !! istart and istop will point to this blank character. Thus, a word 
+  !! convert the word to a number. The last character in the line is
+  !! set to blank so that if any problems occur with finding a word,
+  !! istart and istop will point to this blank character. Thus, a word
   !! will always be returned unless there is a numeric conversion error.
   !! Be sure that the last character in line is not an important character
   !! because it will always be set to blank.
@@ -629,552 +412,559 @@ end subroutine UWWORD
   !! commas separated by one or more spaces as a null word.
   !!
   !! For a word that begins with "'" or '"', the word starts with
-  !! the character after the quote and ends with the character preceding 
+  !! the character after the quote and ends with the character preceding
   !! a subsequent quote. Thus, a quoted word can include spaces and commas.
-  !! The quoted word cannot contain a quote character of the same type 
-  !! within the word but can contain a different quote character. For 
+  !! The quoted word cannot contain a quote character of the same type
+  !! within the word but can contain a different quote character. For
   !! example, "WORD'S" or 'WORD"S'.
   !!
-  !! Number conversion error is written to unit iout if iout is positive; 
-  !! error is written to default output if iout is 0; no error message is 
+  !! Number conversion error is written to unit iout if iout is positive;
+  !! error is written to default output if iout is 0; no error message is
   !! written if iout is negative.
   !!
   !<
-  SUBROUTINE URWORD(LINE,ICOL,ISTART,ISTOP,NCODE,N,R,IOUT,IN)
-    ! -- dummy variables  
-    character(len=*) :: LINE                 !< line to parse
-    integer(I4B), intent(inout) :: icol      !< current column in line
-    integer(I4B), intent(inout) :: istart    !< starting character position of the word
-    integer(I4B), intent(inout) :: istop     !< ending character position of the word
-    integer(I4B), intent(in) :: ncode        !< word conversion flag (1) upper case, (2) integer, (3) real number
-    integer(I4B), intent(inout) :: n         !< integer data type
-    real(DP), intent(inout) :: r             !< float data type
-    integer(I4B), intent(in) :: iout         !< output listing file unit
-    integer(I4B), intent(in) :: in           !< input file unit number
-    ! -- local variables
-    CHARACTER(len=20) STRING                
-    CHARACTER(len=30) RW
-    CHARACTER(len=1) TAB
-    CHARACTER(len=1) CHAREND
+  subroutine URWORD(line, icol, istart, istop, ncode, n, r, iout, in)
+    ! -- dummy
+    character(len=*) :: line !< line to parse
+    integer(I4B), intent(inout) :: icol !< current column in line
+    integer(I4B), intent(inout) :: istart !< starting character position of the word
+    integer(I4B), intent(inout) :: istop !< ending character position of the word
+    integer(I4B), intent(in) :: ncode !< word conversion flag (1) upper case, (2) integer, (3) real number
+    integer(I4B), intent(inout) :: n !< integer data type
+    real(DP), intent(inout) :: r !< float data type
+    integer(I4B), intent(in) :: iout !< output listing file unit
+    integer(I4B), intent(in) :: in !< input file unit number
+    ! -- local
+    character(len=20) string
+    character(len=30) rw
+    character(len=1) tab
+    character(len=1) charend
     character(len=200) :: msg
-    character(len=LINELENGTH) :: msg_line
-    !
-    ! -- code
-    TAB=CHAR(9)
+    character(len=linelength) :: msg_line
+    ! -- formats
+    character(len=*), parameter :: fmtmsgout1 = &
+      "(1X,'FILE UNIT ',I4,' : ERROR CONVERTING ""',A, &
+      & '"" TO ',A,' IN LINE:')"
+    character(len=*), parameter :: fmtmsgout2 = "(1x, &
+      & 'KEYBOARD INPUT : ERROR CONVERTING ""',a,'"" TO ',a,' IN LINE:')"
+    character(len=*), parameter :: fmtmsgout3 = "('File unit ', &
+      & I0,': Error converting ""',a,'"" to ',A,' in following line:')"
+    character(len=*), parameter :: fmtmsgout4 = &
+      "('Keyboard input: Error converting ""',a, &
+      & '"" to ',A,' in following line:')"
+    !
+    tab = char(9)
     !
     ! -- Set last char in LINE to blank and set ISTART and ISTOP to point
     !    to this blank as a default situation when no word is found.  If
     !    starting location in LINE is out of bounds, do not look for a word.
-    LINLEN=LEN(LINE)
-    LINE(LINLEN:LINLEN)=' '
-    ISTART=LINLEN
-    ISTOP=LINLEN
-    LINLEN=LINLEN-1
-    IF(ICOL.LT.1 .OR. ICOL.GT.LINLEN) GO TO 100
+    linlen = len(line)
+    line(linlen:linlen) = ' '
+    istart = linlen
+    istop = linlen
+    linlen = linlen - 1
+    if (icol < 1 .or. icol > linlen) go to 100
     !
     ! -- Find start of word, which is indicated by first character that
     !    is not a blank, a comma, or a tab.
-    DO 10 I=ICOL,LINLEN
-      IF(LINE(I:I).NE.' ' .AND. LINE(I:I).NE.',' .AND. &
-         LINE(I:I).NE.TAB) GO TO 20
-10  CONTINUE
-    ICOL=LINLEN+1
-    GO TO 100
+    do i = icol, linlen
+      if (line(i:i) /= ' ' .and. line(i:i) /= ',' .and. &
+          line(i:i) /= tab) go to 20
+    end do
+    icol = linlen + 1
+    go to 100
     !
     ! -- Found start of word.  Look for end.
     !    When word is quoted, only a quote can terminate it.
-    !    SEARCH FOR A SINGLE (CHAR(39)) OR DOUBLE (CHAR(34)) QUOTE
-20  IF(LINE(I:I).EQ.CHAR(34) .OR. LINE(I:I).EQ.CHAR(39)) THEN
-      IF (LINE(I:I).EQ.CHAR(34)) THEN
-        CHAREND = CHAR(34)
-      ELSE
-        CHAREND = CHAR(39)
-      END IF
-      I=I+1
-      IF(I.LE.LINLEN) THEN
-        DO 25 J=I,LINLEN
-          IF(LINE(J:J).EQ.CHAREND) GO TO 40
-25      CONTINUE
-      END IF
-    !
-    ! -- When word is not quoted, space, comma, or tab will terminate.
-    ELSE
-      DO 30 J=I,LINLEN
-        IF(LINE(J:J).EQ.' ' .OR. LINE(J:J).EQ.',' .OR. &
-           LINE(J:J).EQ.TAB) GO TO 40
-30    CONTINUE
-    END IF
+    !    search for a single (char(39)) or double (char(34)) quote
+20  if (line(i:i) == char(34) .or. line(i:i) == char(39)) then
+      if (line(i:i) == char(34)) then
+        charend = char(34)
+      else
+        charend = char(39)
+      end if
+      i = i + 1
+      if (i <= linlen) then
+        do j = i, linlen
+          if (line(j:j) == charend) go to 40
+        end do
+      end if
+      !
+      ! -- When word is not quoted, space, comma, or tab will terminate.
+    else
+      do j = i, linlen
+        if (line(j:j) == ' ' .or. line(j:j) == ',' .or. &
+            line(j:j) == tab) go to 40
+      end do
+    end if
     !
     ! -- End of line without finding end of word; set end of word to
     !    end of line.
-    J=LINLEN+1
+    j = linlen + 1
     !
     ! -- Found end of word; set J to point to last character in WORD and
     !    set ICOL to point to location for scanning for another word.
-40  ICOL=J+1
-    J=J-1
-    IF(J.LT.I) GO TO 100
-    ISTART=I
-    ISTOP=J
+40  icol = j + 1
+    j = j - 1
+    if (j < i) go to 100
+    istart = i
+    istop = j
     !
     ! -- Convert word to upper case and RETURN if NCODE is 1.
-    IF(NCODE.EQ.1) THEN
-      IDIFF=ICHAR('a')-ICHAR('A')
-      DO 50 K=ISTART,ISTOP
-        IF(LINE(K:K).GE.'a' .AND. LINE(K:K).LE.'z') &
-           LINE(K:K)=CHAR(ICHAR(LINE(K:K))-IDIFF)
-50    CONTINUE
-      RETURN
-    END IF
+    if (ncode == 1) then
+      idiff = ichar('a') - ichar('A')
+      do k = istart, istop
+        if (line(k:k) >= 'a' .and. line(k:k) <= 'z') &
+          line(k:k) = char(ichar(line(k:k)) - idiff)
+      end do
+      return
+    end if
     !
     ! -- Convert word to a number if requested.
-100 IF(NCODE.EQ.2 .OR. NCODE.EQ.3) THEN
-      RW=' '
-      L=30-ISTOP+ISTART
-      IF(L.LT.1) GO TO 200
-      RW(L:30)=LINE(ISTART:ISTOP)
-      IF(NCODE.EQ.2) READ(RW,'(I30)',ERR=200) N
-      IF(NCODE.EQ.3) READ(RW,'(F30.0)',ERR=200) R
-    END IF
-    RETURN
+100 if (ncode == 2 .or. ncode == 3) then
+      rw = ' '
+      l = 30 - istop + istart
+      if (l < 1) go to 200
+      rw(l:30) = line(istart:istop)
+      if (ncode == 2) read (rw, '(i30)', err=200) n
+      if (ncode == 3) read (rw, '(f30.0)', err=200) r
+    end if
+    return
     !
     ! -- Number conversion error.
-200 IF(NCODE.EQ.3) THEN
-      STRING= 'A REAL NUMBER'
-      L=13
-    ELSE
-      STRING= 'AN INTEGER'
-      L=10
-    END IF
+200 if (ncode == 3) then
+      string = 'a real number'
+      l = 13
+    else
+      string = 'an integer'
+      l = 10
+    end if
     !
     ! -- If output unit is negative, set last character of string to 'E'.
-    IF(IOUT.LT.0) THEN
-      N=0
-      R=0.
-      LINE(LINLEN+1:LINLEN+1)='E'
-      RETURN
-    !
-    ! -- If output unit is positive; write a message to output unit.
-    ELSE IF(IOUT.GT.0) THEN
-      IF(IN.GT.0) THEN
-        write(msg_line,201) IN,LINE(ISTART:ISTOP),STRING(1:L)
-      ELSE
-        WRITE(msg_line,202) LINE(ISTART:ISTOP),STRING(1:L)
-      END IF
-      call sim_message(msg_line, iunit=IOUT, skipbefore=1)
-      call sim_message(LINE, iunit=IOUT, fmt='(1x,a)')
-201   FORMAT(1X,'FILE UNIT ',I4,' : ERROR CONVERTING "',A, &
-             '" TO ',A,' IN LINE:')
-202   FORMAT(1X,'KEYBOARD INPUT : ERROR CONVERTING "',A, &
-             '" TO ',A,' IN LINE:')
-    !
-    ! -- If output unit is 0; write a message to default output.
-    ELSE
-      IF(IN.GT.0) THEN
-        write(msg_line,201) IN,LINE(ISTART:ISTOP),STRING(1:L)
-      ELSE
-        WRITE(msg_line,202) LINE(ISTART:ISTOP),STRING(1:L)
-      END IF
-      call sim_message(msg_line, iunit=IOUT, skipbefore=1)
-      call sim_message(LINE, iunit=IOUT, fmt='(1x,a)')
-    END IF
+    if (iout < 0) then
+      n = 0
+      r = 0.
+      line(linlen + 1:linlen + 1) = 'E'
+      return
+      !
+      ! -- If output unit is positive; write a message to output unit.
+    else if (iout > 0) then
+      if (in > 0) then
+        write (msg_line, fmtmsgout1) in, line(istart:istop), string(1:l)
+      else
+        write (msg_line, fmtmsgout2) line(istart:istop), string(1:l)
+      end if
+      call write_message(msg_line, iunit=IOUT, skipbefore=1)
+      call write_message(line, iunit=IOUT, fmt='(1x,a)')
+      !
+      ! -- If output unit is 0; write a message to default output.
+    else
+      if (in > 0) then
+        write (msg_line, fmtmsgout1) in, line(istart:istop), string(1:l)
+      else
+        write (msg_line, fmtmsgout2) line(istart:istop), string(1:l)
+      end if
+      call write_message(msg_line, iunit=iout, skipbefore=1)
+      call write_message(LINE, iunit=iout, fmt='(1x,a)')
+    end if
     !
     ! -- STOP after storing error message.
     call lowcase(string)
     if (in > 0) then
-      write(msg,205) in,line(istart:istop),trim(string)
+      write (msg, fmtmsgout3) in, line(istart:istop), trim(string)
     else
-      write(msg,207) line(istart:istop),trim(string)
-    endif
-205 format('File unit ',I0,': Error converting "',A, &
-           '" to ',A,' in following line:')
-207 format('Keyboard input: Error converting "',A, &
-           '" to ',A,' in following line:')
+      write (msg, fmtmsgout4) line(istart:istop), trim(string)
+    end if
+    !
     call store_error(msg)
     call store_error(trim(line))
     call store_error_unit(in)
     !
-    ! -- return
-END SUBROUTINE URWORD
-
-      SUBROUTINE ULSTLB(IOUT,LABEL,CAUX,NCAUX,NAUX)
-!C     ******************************************************************
-!C     PRINT A LABEL FOR A LIST
-!C     ******************************************************************
-!C
-!C        SPECIFICATIONS:
-!C     ------------------------------------------------------------------
-      CHARACTER(len=*) LABEL
-      CHARACTER(len=16) CAUX(NCAUX)
-      CHARACTER(len=400) BUF
-      CHARACTER(len=1) DASH(400)
-      DATA DASH/400*'-'/
-!C     ------------------------------------------------------------------
-!C
-!C1------Construct the complete label in BUF.  Start with BUF=LABEL.
-      BUF=LABEL
-!C
-!C2------Add auxiliary data names if there are any.
-      NBUF=LEN(LABEL)+9
-      IF(NAUX.GT.0) THEN
-         DO 10 I=1,NAUX
-         N1=NBUF+1
-         NBUF=NBUF+16
-         BUF(N1:NBUF)=CAUX(I)
-10       CONTINUE
-      END IF
-!C
-!C3------Write the label.
-      WRITE(IOUT,103) BUF(1:NBUF)
-  103 FORMAT(1X,A)
-!C
-!C4------Add a line of dashes.
-      WRITE(IOUT,104) (DASH(J),J=1,NBUF)
-  104 FORMAT(1X,400A)
-!C
-!C5------Return.
-      RETURN
-      END SUBROUTINE ULSTLB
-!
-
-      SUBROUTINE UBDSV4(KSTP,KPER,TEXT,NAUX,AUXTXT,IBDCHN, &
-     &          NCOL,NROW,NLAY,NLIST,IOUT,DELT,PERTIM,TOTIM)
-!C     ******************************************************************
-!C     WRITE HEADER RECORDS FOR CELL-BY-CELL FLOW TERMS FOR ONE COMPONENT
-!C     OF FLOW PLUS AUXILIARY DATA USING A LIST STRUCTURE.  EACH ITEM IN
-!C     THE LIST IS WRITTEN BY MODULE UBDSVB
-!C     ******************************************************************
-!C
-!C        SPECIFICATIONS:
-!C     ------------------------------------------------------------------
-      CHARACTER(len=16) :: TEXT
-      character(len=16), dimension(:) :: AUXTXT
-      real(DP),intent(in) :: delt,pertim,totim
-      character(len=*), parameter :: fmt = &
-      "(1X,'UBDSV4 SAVING ',A16,' ON UNIT',I7,' AT TIME STEP',I7,"// &
-      "', STRESS PERIOD',I7)"
-!C     ------------------------------------------------------------------
-!C
-!C1------WRITE UNFORMATTED RECORDS IDENTIFYING DATA.
-      IF(IOUT.GT.0) WRITE(IOUT,fmt) TEXT,IBDCHN,KSTP,KPER
-      WRITE(IBDCHN) KSTP,KPER,TEXT,NCOL,NROW,-NLAY
-      WRITE(IBDCHN) 5,DELT,PERTIM,TOTIM
-      WRITE(IBDCHN) NAUX+1
-      IF(NAUX.GT.0) WRITE(IBDCHN) (AUXTXT(N),N=1,NAUX)
-      WRITE(IBDCHN) NLIST
-!C
-!C2------RETURN
-      RETURN
-      END SUBROUTINE UBDSV4
-
-      SUBROUTINE UBDSVB(IBDCHN,ICRL,Q,VAL,NVL,NAUX,LAUX)
-!C     ******************************************************************
-!C     WRITE ONE VALUE OF CELL-BY-CELL FLOW PLUS AUXILIARY DATA USING
-!C     A LIST STRUCTURE.
-!C     ******************************************************************
-!C
-!C        SPECIFICATIONS:
-!C     ------------------------------------------------------------------
-      real(DP), DIMENSION(nvl) :: VAL
-      real(DP) :: q
-!C     ------------------------------------------------------------------
-!C
-!C1------WRITE CELL NUMBER AND FLOW RATE
-      IF(NAUX.GT.0) THEN
-         N2=LAUX+NAUX-1
-         WRITE(IBDCHN) ICRL,Q,(VAL(N),N=LAUX,N2)
-      ELSE
-         WRITE(IBDCHN) ICRL,Q
-      END IF
-!C
-!C2------RETURN
-      RETURN
-      END SUBROUTINE UBDSVB
-
-  SUBROUTINE UCOLNO(NLBL1,NLBL2,NSPACE,NCPL,NDIG,IOUT)
-!C     ******************************************************************
-!C     OUTPUT COLUMN NUMBERS ABOVE A MATRIX PRINTOUT
-!C        NLBL1 IS THE START COLUMN LABEL (NUMBER)
-!C        NLBL2 IS THE STOP COLUMN LABEL (NUMBER)
-!C        NSPACE IS NUMBER OF BLANK SPACES TO LEAVE AT START OF LINE
-!C        NCPL IS NUMBER OF COLUMN NUMBERS PER LINE
-!C        NDIG IS NUMBER OF CHARACTERS IN EACH COLUMN FIELD
-!C        IOUT IS OUTPUT CHANNEL
-!C     ******************************************************************
-!C
-!C        SPECIFICATIONS:
-!C     ------------------------------------------------------------------
-      CHARACTER(len=1) DOT,SPACE,DG,BF
-      DIMENSION BF(1000),DG(10)
-!C
-      DATA DG(1),DG(2),DG(3),DG(4),DG(5),DG(6),DG(7),DG(8),DG(9),DG(10)/ &
-     &         '0','1','2','3','4','5','6','7','8','9'/
-      DATA DOT,SPACE/'.',' '/
-!C     ------------------------------------------------------------------
-!C
-!C1------CALCULATE # OF COLUMNS TO BE PRINTED (NLBL), WIDTH
-!C1------OF A LINE (NTOT), NUMBER OF LINES (NWRAP).
-      if (iout<=0) return
-      WRITE(IOUT,1)
-    1 FORMAT(1X)
-      NLBL=NLBL2-NLBL1+1
-      N=NLBL
-      IF(NLBL.GT.NCPL) N=NCPL
-      NTOT=NSPACE+N*NDIG
-      IF(NTOT.GT.1000) GO TO 50
-      NWRAP=(NLBL-1)/NCPL + 1
-      J1=NLBL1-NCPL
-      J2=NLBL1-1
-!C
-!C2------BUILD AND PRINT EACH LINE
-      DO 40 N=1,NWRAP
-!C
-!C3------CLEAR THE BUFFER (BF).
-      DO 20 I=1,1000
-      BF(I)=SPACE
-   20 CONTINUE
-      NBF=NSPACE
-!C
-!C4------DETERMINE FIRST (J1) AND LAST (J2) COLUMN # FOR THIS LINE.
-      J1=J1+NCPL
-      J2=J2+NCPL
-      IF(J2.GT.NLBL2) J2=NLBL2
-!C
-!C5------LOAD THE COLUMN #'S INTO THE BUFFER.
-      DO 30 J=J1,J2
-      NBF=NBF+NDIG
-      I2=J/10
-      I1=J-I2*10+1
-      BF(NBF)=DG(I1)
-      IF(I2.EQ.0) GO TO 30
-      I3=I2/10
-      I2=I2-I3*10+1
-      BF(NBF-1)=DG(I2)
-      IF(I3.EQ.0) GO TO 30
-      I4=I3/10
-      I3=I3-I4*10+1
-      BF(NBF-2)=DG(I3)
-      IF(I4.EQ.0) GO TO 30
-      IF(I4.GT.9) THEN
-!C5A-----If more than 4 digits, use "X" for 4th digit.
-         BF(NBF-3)='X'
-      ELSE
-         BF(NBF-3)=DG(I4+1)
-      END IF
-   30 CONTINUE
-!C
-!C6------PRINT THE CONTENTS OF THE BUFFER (I.E. PRINT THE LINE).
-      WRITE(IOUT,31) (BF(I),I=1,NBF)
-   31 FORMAT(1X,1000A1)
-!C
-   40 CONTINUE
-!C
-!C7------PRINT A LINE OF DOTS (FOR AESTHETIC PURPOSES ONLY).
-   50 NTOT=NTOT
-      IF(NTOT.GT.1000) NTOT=1000
-      WRITE(IOUT,51) (DOT,I=1,NTOT)
-   51 FORMAT(1X,1000A1)
-!C
-!C8------RETURN
-      RETURN
-      END SUBROUTINE UCOLNO
-
-      SUBROUTINE ULAPRW(BUF,TEXT,KSTP,KPER,NCOL,NROW,ILAY,IPRN,IOUT)
-!C     ******************************************************************
-!C     PRINT 1 LAYER ARRAY
-!C     ******************************************************************
-!C
-!C        SPECIFICATIONS:
-!C     ------------------------------------------------------------------
-      CHARACTER(len=16) TEXT
-      real(DP),dimension(ncol,nrow) :: buf
-!C     ------------------------------------------------------------------
-!C
-      if (iout<=0) return
-!C1------PRINT A HEADER DEPENDING ON ILAY
-      IF(ILAY.GT.0) THEN
-         WRITE(IOUT,1) TEXT,ILAY,KSTP,KPER
-    1    FORMAT('1',/2X,A,' IN LAYER ',I3,' AT END OF TIME STEP ',I3, &
-     &     ' IN STRESS PERIOD ',I4/2X,75('-'))
-      ELSE IF(ILAY.LT.0) THEN
-         WRITE(IOUT,2) TEXT,KSTP,KPER
-    2    FORMAT('1',/1X,A,' FOR CROSS SECTION AT END OF TIME STEP',I3, &
-     &     ' IN STRESS PERIOD ',I4/1X,79('-'))
-      END IF
-!C
-!C2------MAKE SURE THE FORMAT CODE (IP OR IPRN) IS
-!C2------BETWEEN 1 AND 21.
-      IP=IPRN
-      IF(IP.LT.1 .OR. IP.GT.21) IP=12
-!C
-!C3------CALL THE UTILITY MODULE UCOLNO TO PRINT COLUMN NUMBERS.
-      IF(IP.EQ.1) CALL UCOLNO(1,NCOL,0,11,11,IOUT)
-      IF(IP.EQ.2) CALL UCOLNO(1,NCOL,0,9,14,IOUT)
-      IF(IP.GE.3 .AND. IP.LE.6) CALL UCOLNO(1,NCOL,3,15,8,IOUT)
-      IF(IP.GE.7 .AND. IP.LE.11) CALL UCOLNO(1,NCOL,3,20,6,IOUT)
-      IF(IP.EQ.12) CALL UCOLNO(1,NCOL,0,10,12,IOUT)
-      IF(IP.GE.13 .AND. IP.LE.18) CALL UCOLNO(1,NCOL,3,10,7,IOUT)
-      IF(IP.EQ.19) CALL UCOLNO(1,NCOL,0,5,13,IOUT)
-      IF(IP.EQ.20) CALL UCOLNO(1,NCOL,0,6,12,IOUT)
-      IF(IP.EQ.21) CALL UCOLNO(1,NCOL,0,7,10,IOUT)
-!C
-!C4------LOOP THROUGH THE ROWS PRINTING EACH ONE IN ITS ENTIRETY.
-      DO I=1,NROW
-      SELECT CASE(IP)
-
-      CASE(1)
-!C------------ FORMAT 11G10.3
-      WRITE(IOUT,11) I,(BUF(J,I),J=1,NCOL)
-11    FORMAT(1X,I3,2X,1PG10.3,10(1X,G10.3):/(5X,11(1X,G10.3)))
-
-      CASE(2)
-!C------------ FORMAT 9G13.6
-      WRITE(IOUT,21) I,(BUF(J,I),J=1,NCOL)
-21    FORMAT(1X,I3,2X,1PG13.6,8(1X,G13.6):/(5X,9(1X,G13.6)))
-
-      CASE(3)
-!C------------ FORMAT 15F7.1
-      WRITE(IOUT,31) I,(BUF(J,I),J=1,NCOL)
-31    FORMAT(1X,I3,1X,15(1X,F7.1):/(5X,15(1X,F7.1)))
-
-      CASE(4)
-!C------------ FORMAT 15F7.2
-      WRITE(IOUT,41) I,(BUF(J,I),J=1,NCOL)
-41    FORMAT(1X,I3,1X,15(1X,F7.2):/(5X,15(1X,F7.2)))
-
-      CASE(5)
-!C------------ FORMAT 15F7.3
-      WRITE(IOUT,51) I,(BUF(J,I),J=1,NCOL)
-51    FORMAT(1X,I3,1X,15(1X,F7.3):/(5X,15(1X,F7.3)))
-
-      CASE(6)
-!C------------ FORMAT 15F7.4
-      WRITE(IOUT,61) I,(BUF(J,I),J=1,NCOL)
-61    FORMAT(1X,I3,1X,15(1X,F7.4):/(5X,15(1X,F7.4)))
-
-      CASE(7)
-!C------------ FORMAT 20F5.0
-      WRITE(IOUT,71) I,(BUF(J,I),J=1,NCOL)
-71    FORMAT(1X,I3,1X,20(1X,F5.0):/(5X,20(1X,F5.0)))
-
-      CASE(8)
-!C------------ FORMAT 20F5.1
-      WRITE(IOUT,81) I,(BUF(J,I),J=1,NCOL)
-81    FORMAT(1X,I3,1X,20(1X,F5.1):/(5X,20(1X,F5.1)))
-
-      CASE(9)
-!C------------ FORMAT 20F5.2
-      WRITE(IOUT,91) I,(BUF(J,I),J=1,NCOL)
-91    FORMAT(1X,I3,1X,20(1X,F5.2):/(5X,20(1X,F5.2)))
-
-      CASE(10)
-!C------------ FORMAT 20F5.3
-      WRITE(IOUT,101) I,(BUF(J,I),J=1,NCOL)
-101   FORMAT(1X,I3,1X,20(1X,F5.3):/(5X,20(1X,F5.3)))
-
-      CASE(11)
-!C------------ FORMAT 20F5.4
-      WRITE(IOUT,111) I,(BUF(J,I),J=1,NCOL)
-111   FORMAT(1X,I3,1X,20(1X,F5.4):/(5X,20(1X,F5.4)))
-
-      CASE(12)
-!C------------ FORMAT 10G11.4
-      WRITE(IOUT,121) I,(BUF(J,I),J=1,NCOL)
-121   FORMAT(1X,I3,2X,1PG11.4,9(1X,G11.4):/(5X,10(1X,G11.4)))
-
-      CASE(13)
-!C------------ FORMAT 10F6.0
-      WRITE(IOUT,131) I,(BUF(J,I),J=1,NCOL)
-131   FORMAT(1X,I3,1X,10(1X,F6.0):/(5X,10(1X,F6.0)))
-
-      CASE(14)
-!C------------ FORMAT 10F6.1
-      WRITE(IOUT,141) I,(BUF(J,I),J=1,NCOL)
-141   FORMAT(1X,I3,1X,10(1X,F6.1):/(5X,10(1X,F6.1)))
-
-      CASE(15)
-!C------------ FORMAT 10F6.2
-      WRITE(IOUT,151) I,(BUF(J,I),J=1,NCOL)
-151   FORMAT(1X,I3,1X,10(1X,F6.2):/(5X,10(1X,F6.2)))
-
-      CASE(16)
-!C------------ FORMAT 10F6.3
-      WRITE(IOUT,161) I,(BUF(J,I),J=1,NCOL)
-161   FORMAT(1X,I3,1X,10(1X,F6.3):/(5X,10(1X,F6.3)))
-
-      CASE(17)
-!C------------ FORMAT 10F6.4
-      WRITE(IOUT,171) I,(BUF(J,I),J=1,NCOL)
-171   FORMAT(1X,I3,1X,10(1X,F6.4):/(5X,10(1X,F6.4)))
-
-      CASE(18)
-!C------------ FORMAT 10F6.5
-      WRITE(IOUT,181) I,(BUF(J,I),J=1,NCOL)
-181   FORMAT(1X,I3,1X,10(1X,F6.5):/(5X,10(1X,F6.5)))
+    ! -- Return
+    return
+  end subroutine URWORD
 
-      CASE(19)
-!C------------FORMAT 5G12.5
-      WRITE(IOUT,191) I,(BUF(J,I),J=1,NCOL)
-191   FORMAT(1X,I3,2X,1PG12.5,4(1X,G12.5):/(5X,5(1X,G12.5)))
+  !> @brief Print a label for a list
+  !<
+  subroutine ULSTLB(iout, label, caux, ncaux, naux)
+    ! -- dummy
+    character(len=*) :: label
+    character(len=16) :: caux(ncaux)
+    ! -- local
+    character(len=400) buf
+    ! -- constant
+    character(len=1) DASH(400)
+    data DASH/400*'-'/
+    ! -- formats
+    character(len=*), parameter :: fmtmsgout1 = "(1x, a)"
+    character(len=*), parameter :: fmtmsgout2 = "(1x, 400a)"
+    !
+    ! -- Construct the complete label in BUF.  Start with BUF=LABEL.
+    buf = label
+    !
+    ! -- Add auxiliary data names if there are any.
+    nbuf = len(label) + 9
+    if (naux > 0) then
+      do i = 1, naux
+        n1 = nbuf + 1
+        nbuf = nbuf + 16
+        buf(n1:nbuf) = caux(i)
+      end do
+    end if
+    !
+    ! -- Write the label.
+    write (iout, fmtmsgout1) buf(1:nbuf)
+    !
+    ! -- Add a line of dashes.
+    write (iout, fmtmsgout2) (DASH(j), j=1, nbuf)
+    !
+    ! -- Return
+    return
+  end subroutine ULSTLB
 
-      CASE(20)
-!C------------FORMAT 6G11.4
-      WRITE(IOUT,201) I,(BUF(J,I),J=1,NCOL)
-201   FORMAT(1X,I3,2X,1PG11.4,5(1X,G11.4):/(5X,6(1X,G11.4)))
+  !> @brief Write header records for cell-by-cell flow terms for one component
+  !! of flow plus auxiliary data using a list structure
+  !!
+  !! Each item in the list is written by module UBDSVB
+  !<
+  subroutine UBDSV4(kstp, kper, text, naux, auxtxt, ibdchn, &
+     &              ncol, nrow, nlay, nlist, iout, delt, pertim, totim)
+    ! -- dummy
+    character(len=16) :: text
+    character(len=16), dimension(:) :: auxtxt
+    real(DP), intent(in) :: delt, pertim, totim
+    ! -- formats
+    character(len=*), parameter :: fmt = &
+      & "(1X,'UBDSV4 SAVING ',A16,' ON UNIT',I7,' AT TIME STEP',I7,"// &
+      & "', STRESS PERIOD',I7)"
+    !
+    ! -- Write unformatted records identifying data
+    if (iout > 0) write (iout, fmt) text, ibdchn, kstp, kper
+    write (ibdchn) kstp, kper, text, ncol, nrow, -nlay
+    write (ibdchn) 5, delt, pertim, totim
+    write (ibdchn) naux + 1
+    if (naux > 0) write (ibdchn) (auxtxt(n), n=1, naux)
+    write (ibdchn) nlist
+    !
+    ! -- Return
+    return
+  end subroutine UBDSV4
 
-      CASE(21)
-!C------------FORMAT 7G9.2
-      WRITE(IOUT,211) I,(BUF(J,I),J=1,NCOL)
-211   FORMAT(1X,I3,2X,1PG9.2,6(1X,G9.2):/(5X,7(1X,G9.2)))
+  !> @brief Write one value of cell-by-cell flow plus auxiliary data using a
+  !! list structure
+  !<
+  subroutine UBDSVB(ibdchn, icrl, q, val, nvl, naux, laux)
+    ! -- dummy
+    real(DP), dimension(nvl) :: val
+    real(DP) :: q
+    !
+    ! -- Write cell number and flow rate
+    IF (naux > 0) then
+      n2 = laux + naux - 1
+      write (ibdchn) icrl, q, (val(n), n=laux, n2)
+    else
+      write (ibdchn) icrl, q
+    end if
+    !
+    ! -- Return
+    return
+  end subroutine UBDSVB
 
-      END SELECT
-      END DO
+  !> @brief Output column numbers above a matrix printout
+  !!
+  !! nlbl1 is the start column label (number)
+  !! nlbl2 is the stop column label (number)
+  !! nspace is number of blank spaces to leave at start of line
+  !! ncpl is number of column numbers per line
+  !! ndig is number of characters in each column field
+  !! iout is output channel
+  !<
+  subroutine UCOLNO(nlbl1, nlbl2, nspace, ncpl, ndig, iout)
+    ! -- local
+    character(len=1) :: DOT, SPACE, DG, BF
+    dimension :: BF(1000), DG(10)
+    ! -- constants
+    data DG(1), DG(2), DG(3), DG(4), DG(5), DG(6), DG(7), DG(8), DG(9), DG(10)/ &
+       & '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'/
+    data DOT, SPACE/'.', ' '/
+    ! -- formats
+    character(len=*), parameter :: fmtmsgout1 = "(1x)"
+    character(len=*), parameter :: fmtmsgout2 = "(1x, 1000a1)"
+    !
+    ! -- Calculate # of columns to be printed (nlbl), width
+    !    of a line (ntot), number of lines (nwrap).
+    if (iout <= 0) return
+    write (iout, fmtmsgout1)
+    !
+    nlbl = nlbl2 - nlbl1 + 1
+    n = nlbl
+    !
+    if (nlbl < ncpl) n = ncpl
+    ntot = nspace + n * ndig
+    !
+    if (ntot > 1000) go to 50
+    nwrap = (nlbl - 1) / ncpl + 1
+    j1 = nlbl1 - ncpl
+    j2 = nlbl1 - 1
+    !
+    ! -- Build and print each line
+    do n = 1, nwrap
       !
-      ! -- flush file
-      flush(IOUT)
+      ! -- Clear the buffer (BF)
+      do i = 1, 1000
+        BF(i) = SPACE
+      end do
+      nbf = nspace
       !
-      ! -- return
-      RETURN
-      END SUBROUTINE ULAPRW
-
-     SUBROUTINE ULASAV(BUF,TEXT,KSTP,KPER,PERTIM,TOTIM,NCOL, &
-     &                   NROW,ILAY,ICHN)
-!C     ******************************************************************
-!C     SAVE 1 LAYER ARRAY ON DISK
-!C     ******************************************************************
-!C
-!C        SPECIFICATIONS:
-!C     ------------------------------------------------------------------
-      CHARACTER(len=16) TEXT
-      real(DP),dimension(ncol,nrow) :: buf
-      real(DP) :: pertim,totim
-!C     ------------------------------------------------------------------
-!C
-!C1------WRITE AN UNFORMATTED RECORD CONTAINING IDENTIFYING
-!C1------INFORMATION.
-      WRITE(ICHN) KSTP,KPER,PERTIM,TOTIM,TEXT,NCOL,NROW,ILAY
-!C
-!C2------WRITE AN UNFORMATTED RECORD CONTAINING ARRAY VALUES
-!C2------THE ARRAY IS DIMENSIONED (NCOL,NROW)
-      WRITE(ICHN) ((BUF(IC,IR),IC=1,NCOL),IR=1,NROW)
+      ! -- Determine first (j1) and last (j2) column # for this line.
+      j1 = j1 + ncpl
+      j2 = j2 + ncpl
+      if (j2 > nlbl2) j2 = nlbl2
+      !
+      ! -- Load the column #'s into the buffer.
+      do j = j1, j2
+        nbf = nbf + ndig
+        i2 = j / 10
+        i1 = j - i2 * 10 + 1
+        BF(nbf) = DG(i1)
+        if (i2 == 0) go to 30
+        i3 = i2 / 10
+        i2 = i2 - i3 * 10 + 1
+        BF(nbf - 1) = DG(i2)
+        if (i3 == 0) go to 30
+        i4 = i3 / 10
+        i3 = i3 - i4 * 10 + 1
+        BF(nbf - 2) = DG(i3)
+        if (I4 == 0) go to 30
+        if (I4 > 9) then
+          ! -- If more than 4 digits, use "X" for 4th digit.
+          BF(nbf - 3) = 'X'
+        else
+          BF(nbf - 3) = DG(i4 + 1)
+        end if
+30    end do
+      !
+      ! -- Print the contents of the buffer (i.e. print the line).
+      write (iout, fmtmsgout2) (BF(i), i=1, nbf)
       !
-      ! -- flush file
-      flush(ICHN)
-!C
-!C3------RETURN
-      RETURN
-     END SUBROUTINE ULASAV
+    end do
+    !
+    ! -- Print a line of dots (for aesthetic purposes only).
+50  ntot = ntot
+    if (ntot > 1000) ntot = 1000
+    write (iout, fmtmsgout2) (DOT, i=1, ntot)
+    !
+    ! -- Return
+    return
+  end subroutine UCOLNO
 
+  !> @brief Print 1 layer array
+  !<
+  subroutine ULAPRW(buf, text, kstp, kper, ncol, nrow, ilay, iprn, iout)
+    ! -- dummy
+    character(len=16) :: text
+    real(DP), dimension(ncol, nrow) :: buf
+    ! -- formats
+    character(len=*), parameter :: fmtmsgout1 = &
+      & "('1', /2x, a, ' IN LAYER ',I3,' AT END OF TIME STEP ',I3, &
+      & ' IN STRESS PERIOD ',I4/2x,75('-'))"
+    character(len=*), parameter :: fmtmsgout2 = &
+      & "('1',/1x,A,' FOR CROSS SECTION AT END OF TIME STEP',I3, &
+      & ' IN STRESS PERIOD ',I4/1x,79('-'))"
+    character(len=*), parameter :: fmtg10 = &
+      & "(1X,I3,2X,1PG10.3,10(1X,G10.3):/(5X,11(1X,G10.3)))"
+    character(len=*), parameter :: fmtg13 = &
+      & "(1x,I3,2x,1PG13.6,8(1x,G13.6):/(5x,9(1x,G13.6)))"
+    character(len=*), parameter :: fmtf7pt1 = &
+      & "(1x,I3,1x,15(1x,F7.1):/(5x,15(1x,F7.1)))"
+    character(len=*), parameter :: fmtf7pt2 = &
+      & "(1x,I3,1x,15(1x,F7.2):/(5x,15(1x,F7.2)))"
+    character(len=*), parameter :: fmtf7pt3 = &
+      & "(1x,I3,1x,15(1x,F7.3):/(5x,15(1x,F7.3)))"
+    character(len=*), parameter :: fmtf7pt4 = &
+      & "(1x,I3,1x,15(1x,F7.4):/(5x,15(1x,F7.4)))"
+    character(len=*), parameter :: fmtf5pt0 = &
+      & "(1x,I3,1x,20(1x,F5.0):/(5x,20(1x,F5.0)))"
+    character(len=*), parameter :: fmtf5pt1 = &
+      & "(1x,I3,1x,20(1x,F5.1):/(5x,20(1x,F5.1)))"
+    character(len=*), parameter :: fmtf5pt2 = &
+      & "(1x,I3,1x,20(1x,F5.2):/(5x,20(1x,F5.2)))"
+    character(len=*), parameter :: fmtf5pt3 = &
+      & "(1x,I3,1x,20(1x,F5.3):/(5x,20(1x,F5.3)))"
+    character(len=*), parameter :: fmtf5pt4 = &
+      & "(1x,I3,1x,20(1x,F5.4):/(5x,20(1x,F5.4)))"
+    character(len=*), parameter :: fmtg11 = &
+      & "(1x,I3,2x,1PG11.4,9(1x,G11.4):/(5x,10(1x,G11.4)))"
+    character(len=*), parameter :: fmtf6pt0 = &
+      & "(1x,I3,1x,10(1x,F6.0):/(5X,10(1x,F6.0)))"
+    character(len=*), parameter :: fmtf6pt1 = &
+      & "(1x,I3,1x,10(1x,F6.1):/(5x,10(1x,F6.1)))"
+    character(len=*), parameter :: fmtf6pt2 = &
+      & "(1x,I3,1x,10(1x,F6.2):/(5x,10(1x,F6.2)))"
+    character(len=*), parameter :: fmtf6pt3 = &
+      & "(1x,I3,1x,10(1x,F6.3):/(5x,10(1x,F6.3)))"
+    character(len=*), parameter :: fmtf6pt4 = &
+      & "(1x,I3,1x,10(1x,F6.4):/(5x,10(1x,F6.4)))"
+    character(len=*), parameter :: fmtf6pt5 = &
+      & "(1x,I3,1x,10(1x,F6.5):/(5x,10(1x,F6.5)))"
+    character(len=*), parameter :: fmtg12 = &
+      & "(1x,I3,2x,1PG12.5,4(1x,G12.5):/(5x,5(1x,G12.5)))"
+    character(len=*), parameter :: fmtg11pt4 = &
+      & "(1x,I3,2x,1PG11.4,5(1x,G11.4):/(5x,6(1x,G11.4)))"
+    character(len=*), parameter :: fmtg9pt2 = &
+      & "(1x,I3,2x,1PG9.2,6(1x,G9.2):/(5x,7(1x,G9.2)))"
+    !
+    if (iout <= 0) return
+    ! -- Print a header depending on ilay
+    if (ilay > 0) then
+      write (iout, fmtmsgout1) text, ilay, kstp, kper
+    else if (ilay < 0) then
+      write (iout, fmtmsgout2) text, kstp, kper
+    end if
+    !
+    ! -- Make sure the format code (ip or iprn) is between 1 and 21
+    ip = iprn
+    if (ip < 1 .or. ip > 21) ip = 12
+    !
+    ! -- Call the utility module ucolno to print column numbers.
+    if (ip == 1) call ucolno(1, ncol, 0, 11, 11, iout)
+    if (ip == 2) call ucolno(1, ncol, 0, 9, 14, iout)
+    if (ip >= 3 .and. ip <= 6) call ucolno(1, ncol, 3, 15, 8, iout)
+    if (ip >= 7 .and. ip <= 11) call ucolno(1, ncol, 3, 20, 6, iout)
+    if (ip == 12) call ucolno(1, ncol, 0, 10, 12, iout)
+    if (ip >= 13 .and. ip <= 18) call ucolno(1, ncol, 3, 10, 7, iout)
+    if (ip == 19) call ucolno(1, ncol, 0, 5, 13, iout)
+    if (ip == 20) call ucolno(1, ncol, 0, 6, 12, iout)
+    if (ip == 21) call ucolno(1, ncol, 0, 7, 10, iout)
+    !
+    ! -- Loop through the rows printing each one in its entirety.
+    do i = 1, nrow
+      select case (ip)
+        !
+      case (1)
+        ! -- format 11G10.3
+        write (iout, fmtg10) i, (buf(j, i), j=1, ncol)
+        !
+      case (2)
+        ! -- format 9G13.6
+        write (iout, fmtg13) i, (buf(j, i), j=1, ncol)
+        !
+      case (3)
+        ! -- format 15F7.1
+        write (iout, fmtf7pt1) i, (buf(j, i), j=1, ncol)
+        !
+      case (4)
+        ! -- format 15F7.2
+        write (iout, fmtf7pt2) i, (buf(j, i), j=1, ncol)
+        !
+      case (5)
+        ! -- format 15F7.3
+        write (iout, fmtf7pt3) i, (buf(j, i), j=1, ncol)
+        !
+      case (6)
+        ! -- format 15F7.4
+        write (iout, fmtf7pt4) i, (buf(j, i), j=1, ncol)
+        !
+      case (7)
+        ! -- format 20F5.0
+        write (iout, fmtf5pt0) i, (buf(j, i), j=1, ncol)
+        !
+      case (8)
+        ! -- format 20F5.1
+        write (iout, fmtf5pt1) i, (buf(j, i), j=1, ncol)
+        !
+      case (9)
+        ! -- format 20F5.2
+        write (iout, fmtf5pt2) i, (buf(j, i), j=1, ncol)
+        !
+      case (10)
+        ! -- format 20F5.3
+        write (iout, fmtf5pt3) i, (buf(j, i), j=1, ncol)
+        !
+      case (11)
+        ! -- format 20F5.4
+        write (iout, fmtf5pt4) i, (buf(j, i), j=1, ncol)
+        !
+      case (12)
+        ! -- format 10G11.4
+        write (iout, fmtg11) i, (buf(j, i), j=1, ncol)
+        !
+      case (13)
+        ! -- format 10F6.0
+        write (iout, fmtf6pt0) i, (buf(j, i), j=1, ncol)
+        !
+      case (14)
+        ! -- format 10F6.1
+        write (iout, fmtf6pt1) i, (buf(j, i), j=1, ncol)
+        !
+      case (15)
+        ! -- format 10F6.2
+        write (iout, fmtf6pt2) i, (buf(j, i), j=1, ncol)
+        !
+      case (16)
+        ! -- format 10F6.3
+        write (iout, fmtf6pt3) i, (buf(j, i), j=1, ncol)
+        !
+      case (17)
+        ! -- format 10F6.4
+        write (iout, fmtf6pt4) i, (buf(j, i), j=1, ncol)
+        !
+      case (18)
+        ! -- format 10F6.5
+        write (iout, fmtf6pt5) i, (buf(j, i), j=1, ncol)
+        !
+      case (19)
+        ! -- format 5G12.5
+        write (iout, fmtg12) i, (buf(j, i), j=1, ncol)
+        !
+      case (20)
+        ! -- format 6G11.4
+        write (iout, fmtg11pt4) i, (buf(j, i), j=1, ncol)
+        !
+      case (21)
+        ! -- format 7G9.2
+        write (iout, fmtg9pt2) i, (buf(j, i), j=1, ncol)
+        !
+      end select
+    end do
+    !
+    ! -- Flush file
+    flush (iout)
+    !
+    ! -- Return
+    return
+  end subroutine ULAPRW
+
+  !> @brief Save 1 layer array on disk
+  !<
+  subroutine ulasav(buf, text, kstp, kper, pertim, totim, ncol, nrow, &
+                    ilay, ichn)
+    ! -- dummy
+    character(len=16) :: text
+    real(DP), dimension(ncol, nrow) :: buf
+    real(DP) :: pertim, totim
+    !
+    ! -- Write an unformatted record containing identifying information
+    write (ichn) kstp, kper, pertim, totim, text, ncol, nrow, ilay
+    !
+    ! -- Write an unformatted record containing array values. The array is
+    !    dimensioned (ncol,nrow)
+    write (ichn) ((buf(ic, ir), ic=1, ncol), ir=1, nrow)
+    !
+    ! -- flush file
+    flush (ICHN)
+    !
+    ! -- Return
+    return
+  end subroutine ulasav
+
+  !> @brief Record cell-by-cell flow terms for one component of flow as a 3-D
+  !! array with extra record to indicate delt, pertim, and totim
+  !<
   subroutine ubdsv1(kstp, kper, text, ibdchn, buff, ncol, nrow, nlay, iout, &
                     delt, pertim, totim)
-! ******************************************************************************
-! Record cell-by-cell flow terms for one component of flow as a 3-D array with
-!   extra record to indicate delt, pertim, and totim
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     implicit none
+    ! -- dummy
     integer(I4B), intent(in) :: kstp
     integer(I4B), intent(in) :: kper
     character(len=*), intent(in) :: text
@@ -1189,35 +979,32 @@ subroutine ubdsv1(kstp, kper, text, ibdchn, buff, ncol, nrow, nlay, iout, &
     real(DP), intent(in) :: totim
     ! -- format
     character(len=*), parameter :: fmt = &
-      "(1X,'UBDSV1 SAVING ',A16,' ON UNIT',I7,' AT TIME STEP',I7,"// &
-      "', STRESS PERIOD',I7)"
-! ------------------------------------------------------------------------------
+      & "(1X,'UBDSV1 SAVING ',A16,' ON UNIT',I7,' AT TIME STEP',I7,"// &
+      & "', STRESS PERIOD',I7)"
     !
     ! -- Write records
-    if(iout > 0) write(iout, fmt) text, ibdchn, kstp, kper
-    write(ibdchn) kstp,kper,text,ncol,nrow,-nlay
-    write(ibdchn) 1,delt,pertim,totim
-    write(ibdchn) buff
+    if (iout > 0) write (iout, fmt) text, ibdchn, kstp, kper
+    write (ibdchn) kstp, kper, text, ncol, nrow, -nlay
+    write (ibdchn) 1, delt, pertim, totim
+    write (ibdchn) buff
     !
     ! -- flush file
-    flush(ibdchn)
+    flush (ibdchn)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine ubdsv1
 
-  subroutine ubdsv06(kstp,kper,text,                                 &
-                     modelnam1,paknam1,modelnam2,paknam2,            &
-                     ibdchn,naux,auxtxt,                             &
-                     ncol,nrow,nlay,nlist,iout,delt,pertim,totim)
-! ******************************************************************
-! write header records for cell-by-cell flow terms for one component
-! of flow.  each item in the list is written by module ubdsvc
-! ******************************************************************
-!
-!     specifications:
-! ------------------------------------------------------------------
+  !> @brief Write header records for cell-by-cell flow terms for one component
+  !! of flow.
+  !!
+  !! Each item in the list is written by module ubdsvc
+  !<
+  subroutine ubdsv06(kstp, kper, text, modelnam1, paknam1, modelnam2, paknam2, &
+                     ibdchn, naux, auxtxt, ncol, nrow, nlay, nlist, iout, &
+                     delt, pertim, totim)
     implicit none
+    ! -- dummy
     integer(I4B), intent(in) :: kstp
     integer(I4B), intent(in) :: kper
     character(len=*), intent(in) :: text
@@ -1236,243 +1023,174 @@ subroutine ubdsv06(kstp,kper,text,                                 &
     real(DP), intent(in) :: delt
     real(DP), intent(in) :: pertim
     real(DP), intent(in) :: totim
-    ! -- local variables
+    ! -- local
     integer(I4B) :: n
     ! -- format
     character(len=*), parameter :: fmt = &
-      "(1X,'UBDSV06 SAVING ',A16,' IN MODEL ',A16,' PACKAGE ',A16,"//&
-      "'CONNECTED TO MODEL ',A16,' PACKAGE ',A16,"//                 &
-      "' ON UNIT',I7,' AT TIME STEP',I7,', STRESS PERIOD',I7)"
-! ------------------------------------------------------------------
-!
-! write unformatted records identifying data.
-    if (iout > 0) write(iout,fmt) text, modelnam1, paknam1,          &
-                                  modelnam2, paknam2,                &
-                                  ibdchn, kstp, kper
-    write(ibdchn) kstp,kper,text,ncol,nrow,-nlay
-    write(ibdchn) 6,delt,pertim,totim
-    write(ibdchn) modelnam1
-    write(ibdchn) paknam1
-    write(ibdchn) modelnam2
-    write(ibdchn) paknam2
-    write(ibdchn) naux+1
-    if (naux > 0) write(ibdchn) (auxtxt(n),n=1,naux)
-    write(ibdchn) nlist
+      & "(1X,'UBDSV06 SAVING ',A16,' IN MODEL ',A16,' PACKAGE ',A16,"// &
+      & "'CONNECTED TO MODEL ',A16,' PACKAGE ',A16,"// &
+      & "' ON UNIT',I7,' AT TIME STEP',I7,', STRESS PERIOD',I7)"
+    !
+    ! -- Write unformatted records identifying data.
+    if (iout > 0) write (iout, fmt) text, modelnam1, paknam1, modelnam2, &
+      paknam2, ibdchn, kstp, kper
+    write (ibdchn) kstp, kper, text, ncol, nrow, -nlay
+    write (ibdchn) 6, delt, pertim, totim
+    write (ibdchn) modelnam1
+    write (ibdchn) paknam1
+    write (ibdchn) modelnam2
+    write (ibdchn) paknam2
+    write (ibdchn) naux + 1
+    if (naux > 0) write (ibdchn) (auxtxt(n), n=1, naux)
+    write (ibdchn) nlist
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine ubdsv06
 
+  !> @brief Write one value of cell-by-cell flow using a list structure.
+  !!
+  !! From node (n) and to node (n2) are written to the file
+  !<
   subroutine ubdsvc(ibdchn, n, q, naux, aux)
-! ******************************************************************************
-! Write one value of cell-by-cell flow using a list structure. From node (n)
-! and to node (n2) are written to the file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     implicit none
+    ! -- dummy
     integer(I4B), intent(in) :: ibdchn
     integer(I4B), intent(in) :: n
     real(DP), intent(in) :: q
     integer(I4B), intent(in) :: naux
     real(DP), dimension(naux), intent(in) :: aux
-    ! -- local variables
+    ! -- local
     integer(I4B) :: nn
-! ------------------------------------------------------------------------------
     !
     ! -- Write record
     if (naux > 0) then
-        write(ibdchn) n,q,(aux(nn),nn=1,naux)
+      write (ibdchn) n, q, (aux(nn), nn=1, naux)
     else
-        write(ibdchn) n,q
+      write (ibdchn) n, q
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine ubdsvc
 
+  !> @brief Write one value of cell-by-cell flow using a list structure.
+  !!
+  !! From node (n) and to node (n2) are written to the file
+  !<
   subroutine ubdsvd(ibdchn, n, n2, q, naux, aux)
-! ******************************************************************************
-! Write one value of cell-by-cell flow using a list structure. From node (n)
-! and to node (n2) are written to the file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     implicit none
+    ! -- dummy
     integer(I4B), intent(in) :: ibdchn
     integer(I4B), intent(in) :: n
     integer(I4B), intent(in) :: n2
     real(DP), intent(in) :: q
     integer(I4B), intent(in) :: naux
     real(DP), dimension(naux), intent(in) :: aux
-    ! -- local variables
+    ! -- local
     integer(I4B) :: nn
-! ------------------------------------------------------------------------------
     !
     ! -- Write record
     if (naux > 0) then
-        write(ibdchn) n,n2,q,(aux(nn),nn=1,naux)
+      write (ibdchn) n, n2, q, (aux(nn), nn=1, naux)
     else
-        write(ibdchn) n,n2,q
+      write (ibdchn) n, n2, q
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine ubdsvd
 
+  !> @brief Perform a case-insensitive comparison of two words
+  !<
   logical function same_word(word1, word2)
-    ! Perform a case-insensitive comparison of two words
     implicit none
-    ! -- dummy variables variables
+    ! -- dummy
     character(len=*), intent(in) :: word1, word2
-    ! -- local variables
+    ! -- local
     character(len=200) :: upword1, upword2
     !
     upword1 = word1
     call upcase(upword1)
     upword2 = word2
     call upcase(upword2)
-    same_word = (upword1==upword2)
+    same_word = (upword1 == upword2)
+    !
+    ! -- Return
     return
   end function same_word
 
-  function get_node(ilay, irow, icol, nlay, nrow, ncol)
-    ! Return node number, given layer, row, and column indices
-    ! for a structured grid.  If any argument is invalid,
-    ! return -1.
-    implicit none
-    ! -- return
-    integer(I4B) :: get_node
-    ! -- dummy variables
-    integer(I4B), intent(in) :: ilay, irow, icol, nlay, nrow, ncol
-    !
-    if (nlay>0 .and. nrow>0 .and. ncol>0) then
-      if (ilay>0 .and. ilay<=nlay) then
-        if (irow>0 .and. irow<=nrow) then
-          if (icol>0 .and. icol<=ncol) then
-            get_node = icol + ncol*(irow-1) + (ilay-1)*nrow*ncol
-            return
-          endif
-        endif
-      endif
-    endif
-    get_node = -1
-    return
-  end function get_node
-
-  subroutine get_ijk(nodenumber, nrow, ncol, nlay, irow, icol, ilay)
-    ! Calculate irow, icol, and ilay from the nodenumber and grid
-    ! dimensions.  If nodenumber is invalid, set irow, icol, and
-    ! ilay to -1
-    implicit none
-    ! -- dummy variables
-    integer(I4B), intent(in) :: nodenumber
-    integer(I4B), intent(in) :: nrow
-    integer(I4B), intent(in) :: ncol
-    integer(I4B), intent(in) :: nlay
-    integer(I4B), intent(out) :: irow
-    integer(I4B), intent(out) :: icol
-    integer(I4B), intent(out) :: ilay
-    ! -- local variables
-    integer(I4B) :: nodes
-    integer(I4B) :: ij
-    !
-    nodes = nlay * nrow * ncol
-    if(nodenumber < 1 .or. nodenumber > nodes) then
-      irow = -1
-      icol = -1
-      ilay = -1
-    else
-      ilay = (nodenumber - 1) / (ncol * nrow) + 1
-      ij = nodenumber - (ilay - 1) * ncol * nrow
-      irow = (ij - 1) / ncol + 1
-      icol = ij - (irow - 1) * ncol
-    endif
+  !> @brief Function for string manipulation
+  !<
+  function str_pad_left(str, width) result(res)
+    ! -- local
+    character(len=*), intent(in) :: str
+    integer, intent(in) :: width
+    ! -- Return
+    character(len=max(len_trim(str), width)) :: res
     !
-    return
-  end subroutine get_ijk
-
-  subroutine get_jk(nodenumber, ncpl, nlay, icpl, ilay)
-    ! Calculate icpl, and ilay from the nodenumber and grid
-    ! dimensions.  If nodenumber is invalid, set irow, icol, and
-    ! ilay to -1
-    implicit none
-    ! -- dummy variables
-    integer(I4B), intent(in) :: nodenumber
-    integer(I4B), intent(in) :: ncpl
-    integer(I4B), intent(in) :: nlay
-    integer(I4B), intent(out) :: icpl
-    integer(I4B), intent(out) :: ilay
-    ! -- local variables
-    integer(I4B) :: nodes
-    !
-    nodes = ncpl * nlay
-    if(nodenumber < 1 .or. nodenumber > nodes) then
-      icpl = -1
-      ilay = -1
-    else
-      ilay = (nodenumber - 1) / ncpl + 1
-      icpl = nodenumber - (ilay - 1) * ncpl
-    endif
+    res = str
+    res = adjustr(res)
     !
+    ! -- Return
     return
-  end subroutine get_jk
+  end function
 
   subroutine unitinquire(iu)
-    ! -- dummy variables
+    ! -- dummy
     integer(I4B) :: iu
-    ! -- local variables
+    ! -- local
     character(len=LINELENGTH) :: line
     character(len=100) :: fname, ac, act, fm, frm, seq, unf
     ! -- format
-    character(len=*), parameter :: fmta =                                        &
-       &"('unit:',i4,'  name:',a,'  access:',a,'  action:',a)"                                  
-    character(len=*), parameter :: fmtb =                                        &
-       &"('    formatted:',a,'  sequential:',a,'  unformatted:',a,'  form:',a)"                                  
-    ! -- code
+    character(len=*), parameter :: fmta = &
+       &"('unit:',i4,'  name:',a,'  access:',a,'  action:',a)"
+    character(len=*), parameter :: fmtb = &
+       &"('    formatted:',a,'  sequential:',a,'  unformatted:',a,'  form:',a)"
     !
     ! -- set strings using inquire statement
-    inquire(unit=iu, name=fname, access=ac, action=act, formatted=fm,            &
-            sequential=seq, unformatted=unf, form=frm)
+    inquire (unit=iu, name=fname, access=ac, action=act, formatted=fm, &
+             sequential=seq, unformatted=unf, form=frm)
     !
     ! -- write the results of the inquire statement
-    write(line,fmta) iu, trim(fname), trim(ac), trim(act)
-    call sim_message(line)
-    write(line,fmtb) trim(fm), trim(seq), trim(unf), trim(frm)
-    call sim_message(line)
+    write (line, fmta) iu, trim(fname), trim(ac), trim(act)
+    call write_message(line)
+    write (line, fmtb) trim(fm), trim(seq), trim(unf), trim(frm)
+    call write_message(line)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine unitinquire
 
+  !> @brief Parse a line into words.
+  !!
+  !! Blanks and commas are recognized as delimiters. Multiple blanks between
+  !! words is OK, but multiple commas between words is treated as an error.
+  !! Quotation marks are not recognized as delimiters.
+  !<
   subroutine ParseLine(line, nwords, words, inunit, filename)
-    ! Parse a line into words. Blanks and commas are recognized as
-    ! delimiters. Multiple blanks between words is OK, but multiple
-    ! commas between words is treated as an error. Quotation marks
-    ! are not recognized as delimiters.
+    ! -- modules
     use ConstantsModule, only: LINELENGTH
     implicit none
-    ! -- dummy variables
+    ! -- dummy
     character(len=*), intent(in) :: line
     integer(I4B), intent(inout) :: nwords
     character(len=*), allocatable, dimension(:), intent(inout) :: words
     integer(I4B), intent(in), optional :: inunit
     character(len=*), intent(in), optional :: filename
-    ! -- local variables
+    ! -- local
     integer(I4B) :: i, idum, istart, istop, linelen, lloc
     real(DP) :: rdum
     !
     nwords = 0
     if (allocated(words)) then
-      deallocate(words)
-    endif
+      deallocate (words)
+    end if
     linelen = len(line)
     !
     ! -- get the number of words in a line and allocate words array
     nwords = get_nwords(line)
-    allocate(words(nwords))
+    allocate (words(nwords))
     !
     ! -- Populate words array and return
     lloc = 1
@@ -1481,133 +1199,137 @@ subroutine ParseLine(line, nwords, words, inunit, filename)
       words(i) = line(istart:istop)
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine ParseLine
 
+  !> @brief Print 1 layer array with user formatting in wrap format
+  !<
   subroutine ulaprufw(ncol, nrow, kstp, kper, ilay, iout, buf, text, userfmt, &
                       nvalues, nwidth, editdesc)
-    ! **************************************************************************
-    ! Print 1 layer array with user formatting in wrap format
-    ! **************************************************************************
-    !
-    !    Specifications:
-    ! --------------------------------------------------------------------------
     implicit none
-    ! -- dummy variables
+    ! -- dummy
     integer(I4B), intent(in) :: ncol, nrow, kstp, kper, ilay, iout
-    real(DP),dimension(ncol,nrow), intent(in) :: buf
+    real(DP), dimension(ncol, nrow), intent(in) :: buf
     character(len=*), intent(in) :: text
     character(len=*), intent(in) :: userfmt
     integer(I4B), intent(in) :: nvalues, nwidth
     character(len=1), intent(in) :: editdesc
-    ! -- local variables
+    ! -- local
     integer(I4B) :: i, j, nspaces
-    ! formats
-    1 format('1',/2X,A,' IN LAYER ',I3,' AT END OF TIME STEP ',I3, &
-          ' IN STRESS PERIOD ',I4/2X,75('-'))
-    2 format('1',/1X,A,' FOR CROSS SECTION AT END OF TIME STEP',I3, &
-          ' IN STRESS PERIOD ',I4/1X,79('-'))
-    ! ------------------------------------------------------------------
-    !
-    if (iout<=0) return
+    ! -- formats
+    character(len=*), parameter :: fmtmsgout1 = &
+      "('1',/2X,A,' IN LAYER ',I3,' AT END OF TIME STEP ',I3, &
+&        ' IN STRESS PERIOD ',I4/2X,75('-'))"
+    character(len=*), parameter :: fmtmsgout2 = &
+      "('1',/1X,A,' FOR CROSS SECTION AT END OF TIME STEP',I3, &
+&        ' IN STRESS PERIOD ',I4/1X,79('-'))"
+    !
+    if (iout <= 0) return
     ! -- Print a header depending on ILAY
     if (ilay > 0) then
-       write(iout,1) trim(text), ilay, kstp, kper
-    else if(ilay < 0) then
-       write(iout,2) trim(text), kstp, kper
+      write (iout, fmtmsgout1) trim(text), ilay, kstp, kper
+    else if (ilay < 0) then
+      write (iout, fmtmsgout2) trim(text), kstp, kper
     end if
     !
     ! -- Print column numbers.
     nspaces = 0
     if (editdesc == 'F') nspaces = 3
-    call ucolno(1, ncol, nspaces, nvalues, nwidth+1, iout)
+    call ucolno(1, ncol, nspaces, nvalues, nwidth + 1, iout)
     !
     ! -- Loop through the rows, printing each one in its entirety.
-    do i=1,nrow
-      write(iout,userfmt) i,(buf(j,i),j=1,ncol)
+    do i = 1, nrow
+      write (iout, userfmt) i, (buf(j, i), j=1, ncol)
     end do
     !
     ! -- flush file
-    flush(IOUT)
+    flush (IOUT)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine ulaprufw
 
-  function read_line(iu, eof) result (astring)
-    ! This function reads a line of arbitrary length and returns
-    ! it.  The returned string can be stored in a deferred-length
-    ! character variable, for example:
-    !
-    !    integer(I4B) :: iu
-    !    character(len=:), allocatable :: my_string
-    !    logical :: eof
-    !    iu = 8
-    !    open(iu,file='my_file')
-    !    my_string = read_line(iu, eof)
+  !> @brief This function reads a line of arbitrary length and returns it.
+  !!
+  !! The returned string can be stored in a deferred-length character variable,
+  !! for example:
+  !!
+  !!   integer(I4B) :: iu
+  !!   character(len=:), allocatable :: my_string
+  !!   logical :: eof
+  !!   iu = 8
+  !!   open(iu,file='my_file')
+  !!   my_string = read_line(iu, eof)
+  !<
+  function read_line(iu, eof) result(astring)
     !
     implicit none
-    ! -- dummy variables
-    integer(I4B), intent(in)           :: iu
-    logical, intent(out)          :: eof
+    ! -- dummy
+    integer(I4B), intent(in) :: iu
+    logical, intent(out) :: eof
     character(len=:), allocatable :: astring
-    ! -- local variables
-    integer(I4B)        :: isize, istat
-    character(len=256)  :: buffer
+    ! -- local
+    integer(I4B) :: isize, istat
+    character(len=256) :: buffer
     character(len=1000) :: ermsg, fname
-    character(len=7)    :: fmtd
-    logical             :: lop
-    ! -- format
-20  format('Error in read_line: File ',i0,' is not open.')
-30  format('Error in read_line: Attempting to read text ' // &
-              'from unformatted file: "',a,'"')
-40  format('Error reading from file "',a,'" opened on unit ',i0, &
-              ' in read_line.')
+    character(len=7) :: fmtd
+    logical :: lop
+    ! -- formats
+    character(len=*), parameter :: fmterrmsg1 = &
+      & "('Error in read_line: File ',i0,' is not open.')"
+    character(len=*), parameter :: fmterrmsg2 = &
+      & "('Error in read_line: Attempting to read text ' // &
+      & 'from unformatted file: ""',a,'""')"
+    character(len=*), parameter :: fmterrmsg3 = &
+      & "('Error reading from file ""',a,'"" opened on unit ',i0, &
+      & ' in read_line.')"
     !
     astring = ''
     eof = .false.
     do
-      read(iu, '(a)', advance='NO', iostat=istat, size=isize, end=99) buffer
+      read (iu, '(a)', advance='NO', iostat=istat, size=isize, end=99) buffer
       if (istat > 0) then
         ! Determine error if possible, report it, and stop.
         if (iu <= 0) then
-          ermsg = 'Programming error in call to read_line: ' // &
+          ermsg = 'Programming error in call to read_line: '// &
                   'Attempt to read from unit number <= 0'
         else
-          inquire(unit=iu,opened=lop,name=fname,formatted=fmtd)
+          inquire (unit=iu, opened=lop, name=fname, formatted=fmtd)
           if (.not. lop) then
-            write(ermsg,20) iu
+            write (ermsg, fmterrmsg1) iu
           elseif (fmtd == 'NO' .or. fmtd == 'UNKNOWN') then
-            write(ermsg, 30) trim(fname)
+            write (ermsg, fmterrmsg2) trim(fname)
           else
-            write(ermsg,40) trim(fname), iu
-          endif
-        endif
+            write (ermsg, fmterrmsg3) trim(fname), iu
+          end if
+        end if
         call store_error(ermsg)
         call store_error_unit(iu)
-      endif
-      astring = astring // buffer(:isize)
-      ! An end-of-record condition stops the loop.
+      end if
+      astring = astring//buffer(:isize)
+      ! -- An end-of-record condition stops the loop.
       if (istat < 0) then
         return
-      endif
-    enddo
+      end if
+    end do
     !
     return
 99  continue
+    !
     ! An end-of-file condition returns an empty string.
     eof = .true.
-    return
     !
+    ! -- Return
+    return
   end function read_line
 
   subroutine GetFileFromPath(pathname, filename)
     implicit none
-    ! -- dummy variables
+    ! -- dummy
     character(len=*), intent(in) :: pathname
     character(len=*), intent(out) :: filename
-    ! -- local variables
+    ! -- local
     integer(I4B) :: i, istart, istop, lenpath
     character(len=1) :: fs = '/'
     character(len=1) :: bs = '\'
@@ -1616,40 +1338,44 @@ subroutine GetFileFromPath(pathname, filename)
     lenpath = len_trim(pathname)
     istart = 1
     istop = lenpath
-    loop: do i=lenpath,1,-1
+    loop: do i = lenpath, 1, -1
       if (pathname(i:i) == fs .or. pathname(i:i) == bs) then
         if (i == istop) then
           istop = istop - 1
         else
           istart = i + 1
           exit loop
-        endif
-      endif
-    enddo loop
+        end if
+      end if
+    end do loop
     if (istop >= istart) then
       filename = pathname(istart:istop)
-    endif
+    end if
     !
+    ! -- Return
     return
   end subroutine GetFileFromPath
 
+  !> @brief Starting at position icol, define string as line(istart:istop).
+  !!
+  !! If string can be interpreted as an integer(I4B), return integer in idnum
+  !! argument. If token is not an integer(I4B), assume it is a boundary name,
+  !! return NAMEDBOUNDFLAG in idnum, convert string to uppercase and return it
+  !! in bndname.
+  !<
   subroutine extract_idnum_or_bndname(line, icol, istart, istop, idnum, bndname)
-    ! Starting at position icol, define string as line(istart:istop).
-    ! If string can be interpreted as an integer(I4B), return integer in idnum argument.
-    ! If token is not an integer(I4B), assume it is a boundary name, return NAMEDBOUNDFLAG
-    ! in idnum, convert string to uppercase and return it in bndname.
     implicit none
-    ! -- dummy variables
-    character(len=*),            intent(inout) :: line
-    integer(I4B),                     intent(inout) :: icol, istart, istop
-    integer(I4B),                     intent(out)   :: idnum
-    character(len=LENBOUNDNAME), intent(out)   :: bndname
-    ! -- local variables
-    integer(I4B) :: istat, ndum, ncode=0
+    ! -- dummy
+    character(len=*), intent(inout) :: line
+    integer(I4B), intent(inout) :: icol, istart, istop
+    integer(I4B), intent(out) :: idnum
+    character(len=LENBOUNDNAME), intent(out) :: bndname
+    ! -- local
+    integer(I4B) :: istat, ndum, ncode = 0
     real(DP) :: rdum
     !
     call urword(line, icol, istart, istop, ncode, ndum, rdum, 0, 0)
-    read(line(istart:istop),*,iostat=istat) ndum
+    read (line(istart:istop), *, iostat=istat) ndum
     if (istat == 0) then
       idnum = ndum
       bndname = ''
@@ -1657,24 +1383,21 @@ subroutine extract_idnum_or_bndname(line, icol, istart, istop, idnum, bndname)
       idnum = NAMEDBOUNDFLAG
       bndname = line(istart:istop)
       call upcase(bndname)
-    endif
+    end if
     !
+    ! -- Return
     return
   end subroutine extract_idnum_or_bndname
 
+  !> @brief Read auxiliary variables from an input line
+  !<
   subroutine urdaux(naux, inunit, iout, lloc, istart, istop, auxname, line, text)
-! ******************************************************************************
-! Read auxiliary variables from an input line
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ArrayHandlersModule, only: ExpandArray
-    use ConstantsModule,     only: LENAUXNAME
+    use ConstantsModule, only: LENAUXNAME
     ! -- implicit
     implicit none
-    ! -- dummy variables
+    ! -- dummy
     integer(I4B), intent(inout) :: naux
     integer(I4B), intent(in) :: inunit
     integer(I4B), intent(in) :: iout
@@ -1684,18 +1407,19 @@ subroutine urdaux(naux, inunit, iout, lloc, istart, istop, auxname, line, text)
     character(len=LENAUXNAME), allocatable, dimension(:), intent(inout) :: auxname
     character(len=*), intent(inout) :: line
     character(len=*), intent(in) :: text
-    ! -- local variables
+    ! -- local
     integer(I4B) :: n, linelen
     integer(I4B) :: iauxlen
     real(DP) :: rval
-! ------------------------------------------------------------------------------
+    !
     linelen = len(line)
-    if(naux > 0) then
-      write(errmsg,'(a)') 'Auxiliary variables already specified. Auxiliary ' // &
-        'variables must be specified on one line in the options block.'
+    if (naux > 0) then
+      write (errmsg, '(a)') 'Auxiliary variables already specified. '// &
+        & 'Auxiliary variables must be specified on one line in the '// &
+        & 'options block.'
       call store_error(errmsg)
       call store_error_unit(inunit)
-    endif
+    end if
     auxloop: do
       call urword(line, lloc, istart, istop, 1, n, rval, iout, inunit)
       if (istart >= linelen) exit auxloop
@@ -1708,57 +1432,53 @@ subroutine urdaux(naux, inunit, iout, lloc, istart, istop, auxname, line, text)
           & to ', LENAUXNAME, ' characters.'
         call store_error(errmsg)
         call store_error_unit(inunit)
-      end if      
+      end if
       naux = naux + 1
       call ExpandArray(auxname)
       auxname(naux) = line(istart:istop)
-      if(iout > 0) then
-        write(iout, "(4X,'AUXILIARY ',a,' VARIABLE: ',A)")                     &
+      if (iout > 0) then
+        write (iout, "(4X,'AUXILIARY ',a,' VARIABLE: ',A)") &
           trim(adjustl(text)), auxname(naux)
-      endif
-    enddo auxloop
+      end if
+    end do auxloop
     !
+    ! -- Return
     return
   end subroutine urdaux
 
+  !> @brief Define the print or save format
+  !!
+  !! Define cdatafmp as a Fortran output format based on user input. Also define
+  !! nvalues, nwidth, and editdesc.
+  !!
+  !! Syntax for linein:
+  !!   COLUMNS nval WIDTH nwid [DIGITS ndig [options]]
+  !!
+  !! Where:
+  !!   nval = Number of values per line.
+  !!   nwid = Number of character places to be used for each value.
+  !!   ndig = Number of digits to the right of the decimal point (required
+  !!          for real array).
+  !!   options are:
+  !!          editoption: One of [EXPONENTIAL, FIXED, GENERAL, SCIENTIFIC]
+  !! A default value should be passed in for editdesc as G, I, E, F, or S.
+  !! If I is passed in, then the fortran format will be for an integer variable.
+  !<
   subroutine print_format(linein, cdatafmp, editdesc, nvaluesp, nwidthp, inunit)
-! ******************************************************************************
-! print_format -- define the print or save format
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-! Define cdatafmp as a Fortran output format based on user input.  Also define
-! nvalues, nwidth, and editdesc.
-!
-!   Syntax for linein:
-!     COLUMNS nval WIDTH nwid [DIGITS ndig [options]]
-!
-! Where:
-!     nval = Number of values per line.
-!     nwid = Number of character places to be used for each value.
-!     ndig = Number of digits to the right of the decimal point (required
-!            for real array).
-!     options are:
-!            editoption: One of [EXPONENTIAL, FIXED, GENERAL, SCIENTIFIC]
-! A default value should be passed in for editdesc as G, I, E, F, or S.
-! If I is passed in, then the fortran format will be for an integer variable.
-! ------------------------------------------------------------------------------
-    ! -- dummy variables
+    ! -- dummy
     character(len=*), intent(in) :: linein
     character(len=*), intent(inout) :: cdatafmp
     character(len=*), intent(inout) :: editdesc
     integer(I4B), intent(inout) :: nvaluesp
     integer(I4B), intent(inout) :: nwidthp
     integer(I4B), intent(in) :: inunit
-    ! -- local variables
+    ! -- local
     character(len=len(linein)) :: line
     character(len=20), dimension(:), allocatable :: words
     character(len=100) :: ermsg
-    integer(I4B) :: ndigits=0, nwords=0
+    integer(I4B) :: ndigits = 0, nwords = 0
     integer(I4B) :: i, ierr
     logical :: isint
-! ------------------------------------------------------------------------------
     !
     ! -- Parse line and initialize values
     line(:) = linein(:)
@@ -1766,17 +1486,17 @@ subroutine print_format(linein, cdatafmp, editdesc, nvaluesp, nwidthp, inunit)
     ierr = 0
     i = 0
     isint = .false.
-    if(editdesc == 'I') isint = .true.
+    if (editdesc == 'I') isint = .true.
     !
     ! -- Check array name
     if (nwords < 1) then
-      ermsg = 'Could not build PRINT_FORMAT from line' // trim(line)
+      ermsg = 'Could not build PRINT_FORMAT from line'//trim(line)
       call store_error(trim(ermsg))
       ermsg = 'Syntax is: COLUMNS <columns> WIDTH <width> DIGITS &
               &<digits> <format>'
       call store_error(trim(ermsg))
       call store_error_unit(inunit)
-    endif
+    end if
     !
     ermsg = 'Error setting PRINT_FORMAT. Syntax is incorrect in line:'
     if (nwords >= 4) then
@@ -1784,14 +1504,14 @@ subroutine print_format(linein, cdatafmp, editdesc, nvaluesp, nwidthp, inunit)
       if (.not. same_word(words(3), 'WIDTH')) ierr = 1
       ! -- Read nvalues and nwidth
       if (ierr == 0) then
-        read(words(2), *, iostat=ierr) nvaluesp
-      endif
+        read (words(2), *, iostat=ierr) nvaluesp
+      end if
       if (ierr == 0) then
-        read(words(4), *, iostat=ierr) nwidthp
-      endif
+        read (words(4), *, iostat=ierr) nwidthp
+      end if
     else
       ierr = 1
-    endif
+    end if
     if (ierr /= 0) then
       call store_error(ermsg)
       call store_error(line)
@@ -1799,7 +1519,7 @@ subroutine print_format(linein, cdatafmp, editdesc, nvaluesp, nwidthp, inunit)
               &DIGITS <digits> <format>'
       call store_error(trim(ermsg))
       call store_error_unit(inunit)
-    endif
+    end if
     i = 4
     !
     if (.not. isint) then
@@ -1807,12 +1527,12 @@ subroutine print_format(linein, cdatafmp, editdesc, nvaluesp, nwidthp, inunit)
       if (nwords >= 5) then
         if (.not. same_word(words(5), 'DIGITS')) ierr = 1
         ! -- Read ndigits
-        read(words(6), *, iostat=ierr) ndigits
+        read (words(6), *, iostat=ierr) ndigits
       else
         ierr = 1
-      endif
+      end if
       i = i + 2
-    endif
+    end if
     !
     ! -- Check for EXPONENTIAL | FIXED | GENERAL | SCIENTIFIC option.
     ! -- Check for LABEL, WRAP, and STRIP options.
@@ -1834,7 +1554,7 @@ subroutine print_format(linein, cdatafmp, editdesc, nvaluesp, nwidthp, inunit)
           editdesc = 'S'
           if (isint) ierr = 1
         case default
-          ermsg = 'Error in format specification. Unrecognized option: ' // words(i)
+          ermsg = 'Error in format specification. Unrecognized option: '//words(i)
           call store_error(ermsg)
           ermsg = 'Valid values are EXPONENTIAL, FIXED, GENERAL, or SCIENTIFIC.'
           call store_error(ermsg)
@@ -1842,13 +1562,13 @@ subroutine print_format(linein, cdatafmp, editdesc, nvaluesp, nwidthp, inunit)
         end select
       else
         exit
-      endif
-    enddo
+      end if
+    end do
     if (ierr /= 0) then
       call store_error(ermsg)
       call store_error(line)
       call store_error_unit(inunit)
-    endif
+    end if
     !
     ! -- Build the output format.
     select case (editdesc)
@@ -1860,178 +1580,183 @@ subroutine print_format(linein, cdatafmp, editdesc, nvaluesp, nwidthp, inunit)
       call BuildFloatFormat(nvaluesp, nwidthp, ndigits, editdesc, cdatafmp)
     end select
     !
+    ! -- Return
     return
   end subroutine print_format
 
+  !> @brief Build a fixed format for printing or saving a real array
+  !<
   subroutine BuildFixedFormat(nvalsp, nwidp, ndig, outfmt, prowcolnum)
-    ! Build a fixed format for printing or saving a real array
     implicit none
-    ! -- dummy variables
+    ! -- dummy
     integer(I4B), intent(in) :: nvalsp, nwidp, ndig
     character(len=*), intent(inout) :: outfmt
-    logical, intent(in), optional :: prowcolnum  ! default true
-    ! -- local variables
-    character(len=8)   :: cvalues, cwidth, cdigits
-    character(len=60)  :: ufmt
+    logical, intent(in), optional :: prowcolnum ! default true
+    ! -- local
+    character(len=8) :: cvalues, cwidth, cdigits
+    character(len=60) :: ufmt
     logical :: prowcolnumlocal
-    ! formats
-    10 format(i8)
+    ! -- formats
+    character(len=*), parameter :: fmtndig = "(i8)"
     !
     if (present(prowcolnum)) then
       prowcolnumlocal = prowcolnum
     else
       prowcolnumlocal = .true.
-    endif
+    end if
     !
     ! -- Convert integers to characters and left-adjust
-    write(cdigits,10) ndig
+    write (cdigits, fmtndig) ndig
     cdigits = adjustl(cdigits)
     !
     ! -- Build format for printing to the list file in wrap format
-    write(cvalues,10) nvalsp
+    write (cvalues, fmtndig) nvalsp
     cvalues = adjustl(cvalues)
-    write(cwidth,10) nwidp
+    write (cwidth, fmtndig) nwidp
     cwidth = adjustl(cwidth)
     if (prowcolnumlocal) then
       ufmt = '(1x,i3,1x,'
     else
       ufmt = '(5x,'
-    endif
-    ufmt = trim(ufmt) // cvalues
-    ufmt = trim(ufmt) // '(1x,f'
-    ufmt = trim(ufmt) // cwidth
-    ufmt = trim(ufmt) // '.'
-    ufmt = trim(ufmt) // cdigits
-    ufmt = trim(ufmt) // '):/(5x,'
-    ufmt = trim(ufmt) // cvalues
-    ufmt = trim(ufmt) // '(1x,f'
-    ufmt = trim(ufmt) // cwidth
-    ufmt = trim(ufmt) // '.'
-    ufmt = trim(ufmt) // cdigits
-    ufmt = trim(ufmt) // ')))'
+    end if
+    !
+    ufmt = trim(ufmt)//cvalues
+    ufmt = trim(ufmt)//'(1x,f'
+    ufmt = trim(ufmt)//cwidth
+    ufmt = trim(ufmt)//'.'
+    ufmt = trim(ufmt)//cdigits
+    ufmt = trim(ufmt)//'):/(5x,'
+    ufmt = trim(ufmt)//cvalues
+    ufmt = trim(ufmt)//'(1x,f'
+    ufmt = trim(ufmt)//cwidth
+    ufmt = trim(ufmt)//'.'
+    ufmt = trim(ufmt)//cdigits
+    ufmt = trim(ufmt)//')))'
     outfmt = ufmt
     !
+    ! -- Return
     return
   end subroutine BuildFixedFormat
 
+  !> @brief Build a floating-point format for printing or saving a real array
+  !<
   subroutine BuildFloatFormat(nvalsp, nwidp, ndig, editdesc, outfmt, prowcolnum)
-    ! Build a floating-point format for printing or saving a real array
     implicit none
-    ! -- dummy variables
+    ! -- dummy
     integer(I4B), intent(in) :: nvalsp, nwidp, ndig
     character(len=*), intent(in) :: editdesc
     character(len=*), intent(inout) :: outfmt
-    logical, intent(in), optional :: prowcolnum  ! default true
-    ! -- local variables
-    character(len=8)   :: cvalues,  cwidth, cdigits
-    character(len=60)  :: ufmt
+    logical, intent(in), optional :: prowcolnum ! default true
+    ! -- local
+    character(len=8) :: cvalues, cwidth, cdigits
+    character(len=60) :: ufmt
     logical :: prowcolnumlocal
-    ! formats
-    10 format(i8)
+    ! -- formats
+    character(len=*), parameter :: fmtndig = "(i8)"
     !
     if (present(prowcolnum)) then
       prowcolnumlocal = prowcolnum
     else
       prowcolnumlocal = .true.
-    endif
+    end if
     !
     ! -- Build the format
-    write(cdigits,10) ndig
+    write (cdigits, fmtndig) ndig
     cdigits = adjustl(cdigits)
     ! -- Convert integers to characters and left-adjust
-    write(cwidth,10) nwidp
+    write (cwidth, fmtndig) nwidp
     cwidth = adjustl(cwidth)
     ! -- Build format for printing to the list file
-    write(cvalues, 10) (nvalsp - 1)
+    write (cvalues, fmtndig) (nvalsp - 1)
     cvalues = adjustl(cvalues)
     if (prowcolnumlocal) then
-      ufmt = '(1x,i3,2x,1p,' // editdesc
+      ufmt = '(1x,i3,2x,1p,'//editdesc
     else
-      ufmt = '(6x,1p,' // editdesc
-    endif
-    ufmt = trim(ufmt) // cwidth
-    ufmt = trim(ufmt) // '.'
-    ufmt = trim(ufmt) // cdigits
-    if (nvalsp>1) then
-      ufmt = trim(ufmt) // ','
-      ufmt = trim(ufmt) // cvalues
-      ufmt = trim(ufmt) // '(1x,'
-      ufmt = trim(ufmt) // editdesc
-      ufmt = trim(ufmt) // cwidth
-      ufmt = trim(ufmt) // '.'
-      ufmt = trim(ufmt) // cdigits
-      ufmt = trim(ufmt) // ')'
-    endif
-    ufmt = trim(ufmt) // ':/(5x,'
-    write(cvalues, 10) nvalsp
+      ufmt = '(6x,1p,'//editdesc
+    end if
+    ufmt = trim(ufmt)//cwidth
+    ufmt = trim(ufmt)//'.'
+    ufmt = trim(ufmt)//cdigits
+    if (nvalsp > 1) then
+      ufmt = trim(ufmt)//','
+      ufmt = trim(ufmt)//cvalues
+      ufmt = trim(ufmt)//'(1x,'
+      ufmt = trim(ufmt)//editdesc
+      ufmt = trim(ufmt)//cwidth
+      ufmt = trim(ufmt)//'.'
+      ufmt = trim(ufmt)//cdigits
+      ufmt = trim(ufmt)//')'
+    end if
+    !
+    ufmt = trim(ufmt)//':/(5x,'
+    write (cvalues, fmtndig) nvalsp
     cvalues = adjustl(cvalues)
-    ufmt = trim(ufmt) // cvalues
-    ufmt = trim(ufmt) // '(1x,'
-    ufmt = trim(ufmt) // editdesc
-    ufmt = trim(ufmt) // cwidth
-    ufmt = trim(ufmt) // '.'
-    ufmt = trim(ufmt) // cdigits
-    ufmt = trim(ufmt) // ')))'
+    ufmt = trim(ufmt)//cvalues
+    ufmt = trim(ufmt)//'(1x,'
+    ufmt = trim(ufmt)//editdesc
+    ufmt = trim(ufmt)//cwidth
+    ufmt = trim(ufmt)//'.'
+    ufmt = trim(ufmt)//cdigits
+    ufmt = trim(ufmt)//')))'
     outfmt = ufmt
     !
+    ! -- Return
     return
   end subroutine BuildFloatFormat
 
+  !> @brief Build a format for printing or saving an integer array
+  !<
   subroutine BuildIntFormat(nvalsp, nwidp, outfmt, prowcolnum)
-    ! Build a format for printing or saving an integer array
     implicit none
-    ! -- dummy variables
+    ! -- dummy
     integer(I4B), intent(in) :: nvalsp, nwidp
     character(len=*), intent(inout) :: outfmt
-    logical, intent(in), optional :: prowcolnum  ! default true
-    ! -- local variables
-    character(len=8)   :: cvalues, cwidth
-    character(len=60)  :: ufmt
+    logical, intent(in), optional :: prowcolnum ! default true
+    ! -- local
+    character(len=8) :: cvalues, cwidth
+    character(len=60) :: ufmt
     logical :: prowcolnumlocal
-    ! formats
-    10 format(i8)
+    ! -- formats
+    character(len=*), parameter :: fmtndig = "(i8)"
     !
     if (present(prowcolnum)) then
       prowcolnumlocal = prowcolnum
     else
       prowcolnumlocal = .true.
-    endif
+    end if
     !
     ! -- Build format for printing to the list file in wrap format
-    write(cvalues,10)nvalsp
+    write (cvalues, fmtndig) nvalsp
     cvalues = adjustl(cvalues)
-    write(cwidth,10)nwidp
+    write (cwidth, fmtndig) nwidp
     cwidth = adjustl(cwidth)
     if (prowcolnumlocal) then
       ufmt = '(1x,i3,1x,'
     else
       ufmt = '(5x,'
-    endif
-    ufmt = trim(ufmt) // cvalues
-    ufmt = trim(ufmt) // '(1x,i'
-    ufmt = trim(ufmt) // cwidth
-    ufmt = trim(ufmt) // '):/(5x,'
-    ufmt = trim(ufmt) // cvalues
-    ufmt = trim(ufmt) // '(1x,i'
-    ufmt = trim(ufmt) // cwidth
-    ufmt = trim(ufmt) // ')))'
+    end if
+    ufmt = trim(ufmt)//cvalues
+    ufmt = trim(ufmt)//'(1x,i'
+    ufmt = trim(ufmt)//cwidth
+    ufmt = trim(ufmt)//'):/(5x,'
+    ufmt = trim(ufmt)//cvalues
+    ufmt = trim(ufmt)//'(1x,i'
+    ufmt = trim(ufmt)//cwidth
+    ufmt = trim(ufmt)//')))'
     outfmt = ufmt
     !
+    ! -- Return
     return
   end subroutine BuildIntFormat
 
-
   !> @brief Get the number of words in a string
-  !!
-  !! Function to get the number of words in a string
-  !!
   !<
   function get_nwords(line)
-    ! -- return variable
-    integer(I4B) :: get_nwords            !< number of words in a string
-    ! -- dummy variables
-    character(len=*), intent(in) :: line  !< line
-    ! -- local variables
+    ! -- return
+    integer(I4B) :: get_nwords !< number of words in a string
+    ! -- dummy
+    character(len=*), intent(in) :: line !< line
+    ! -- local
     integer(I4B) :: linelen
     integer(I4B) :: lloc
     integer(I4B) :: istart
@@ -2051,108 +1776,103 @@ function get_nwords(line)
       get_nwords = get_nwords + 1
     end do
     !
-    ! -- return
+    ! -- Return
     return
   end function get_nwords
 
+  !> @brief Move the file pointer.
+  !!
+  !! Patterned after fseek, which is not supported as part of the fortran
+  !! standard.  For this subroutine to work the file must have been opened with
+  !! access='stream' and action='readwrite'.
+  !<
   subroutine fseek_stream(iu, offset, whence, status)
-! ******************************************************************************
-! Move the file pointer.  Patterned after fseek, which is not 
-! supported as part of the fortran standard.  For this subroutine to work
-! the file must have been opened with access='stream' and action='readwrite'.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     integer(I4B), intent(in) :: iu
     integer(I4B), intent(in) :: offset
     integer(I4B), intent(in) :: whence
     integer(I4B), intent(inout) :: status
+    ! -- local
     integer(I8B) :: ipos
-! ------------------------------------------------------------------------------
     !
-    inquire(unit=iu, size=ipos)
-    
-    select case(whence)
-    case(0)
+    inquire (unit=iu, size=ipos)
+    !
+    select case (whence)
+    case (0)
       !
       ! -- whence = 0, offset is relative to start of file
       ipos = 0 + offset
-    case(1)
+    case (1)
       !
       ! -- whence = 1, offset is relative to current pointer position
-      inquire(unit=iu, pos=ipos)
+      inquire (unit=iu, pos=ipos)
       ipos = ipos + offset
-    case(2)
+    case (2)
       !
       ! -- whence = 2, offset is relative to end of file
-      inquire(unit=iu, size=ipos)
+      inquire (unit=iu, size=ipos)
       ipos = ipos + offset
     end select
     !
     ! -- position the file pointer to ipos
-    write(iu, pos=ipos, iostat=status)
-    inquire(unit=iu, pos=ipos)
+    write (iu, pos=ipos, iostat=status)
+    inquire (unit=iu, pos=ipos)
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine fseek_stream
-  
+
+  !> @brief Read until non-comment line found and then return line.
+  !!
+  !! Different from u8rdcom in that line is a deferred length character string,
+  !! which allows any length lines to be read using the get_line subroutine.
+  !<
   subroutine u9rdcom(iin, iout, line, ierr)
-! ******************************************************************************
-! Read until non-comment line found and then return line.  Different from
-! u8rdcom in that line is a deferred length character string, which allows
-! any length lines to be read using the get_line subroutine.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- module
     use, intrinsic :: iso_fortran_env, only: IOSTAT_END
     implicit none
-    ! -- dummy variables
-    integer(I4B),         intent(in) :: iin
-    integer(I4B),         intent(in) :: iout
-    character (len=:), allocatable, intent(inout) :: line
-    integer(I4B),        intent(out) :: ierr
-    ! -- local variables
-    character (len=:), allocatable :: linetemp
-    character (len=2), parameter :: comment = '//'
-    character(len=1), parameter  :: tab = CHAR(9)
+    ! -- dummy
+    integer(I4B), intent(in) :: iin
+    integer(I4B), intent(in) :: iout
+    character(len=:), allocatable, intent(inout) :: line
+    integer(I4B), intent(out) :: ierr
+    ! -- local
+    character(len=:), allocatable :: linetemp
+    character(len=2), parameter :: comment = '//'
+    character(len=1), parameter :: tab = CHAR(9)
     logical :: iscomment
     integer(I4B) :: i, j, l, istart, lsize
-! ------------------------------------------------------------------------------
-    !code
     !
     !readerrmsg = ''
     line = comment
     pcomments: do
       call get_line(iin, line, ierr)
       if (ierr == IOSTAT_END) then
-        ! -- End of file reached.
-        ! -- Backspace is needed for gfortran.
-        backspace(iin)
+        ! -- End of file reached. Return with ierr = IOSTAT_END
+        !    and line as an empty string
         line = ' '
         exit pcomments
       elseif (ierr /= 0) then
         ! -- Other error...report it
         call unitinquire(iin)
-        write(errmsg, *) 'u9rdcom: Could not read from unit: ',iin
+        write (errmsg, *) 'u9rdcom: Could not read from unit: ', iin
         call store_error(errmsg, terminate=.TRUE.)
-      endif
-      if (len_trim(line).lt.1) then
+      end if
+      if (len_trim(line) < 1) then
         line = comment
         cycle
       end if
       !
-      ! Ensure that any initial tab characters are treated as spaces
+      ! -- Ensure that any initial tab characters are treated as spaces
       cleartabs: do
         !
         ! -- adjustl manually to avoid stack overflow
         lsize = len(line)
         istart = 1
-        allocate(character(len=lsize) :: linetemp)
+        allocate (character(len=lsize) :: linetemp)
         do j = 1, lsize
-          if (line(j:j) /= ' ' .and. line(j:j) /= ',' .and. line(j:j) /= char(9)) then
+          if (line(j:j) /= ' ' .and. line(j:j) /= ',' .and. &
+              line(j:j) /= char(9)) then
             istart = j
             exit
           end if
@@ -2160,65 +1880,64 @@ subroutine u9rdcom(iin, iout, line, ierr)
         linetemp(:) = ' '
         linetemp(:) = line(istart:)
         line(:) = linetemp(:)
-        deallocate(linetemp)
+        deallocate (linetemp)
         !
         ! -- check for comment
         iscomment = .false.
         select case (line(1:1))
-          case ('#')
-            iscomment = .true.
-            exit cleartabs
-          case ('!')
-            iscomment = .true.
-            exit cleartabs
-          case (tab)
-            line(1:1) = ' '
-            cycle cleartabs
-          case default
-            if (line(1:2).eq.comment) iscomment = .true.
-            if (len_trim(line) < 1) iscomment = .true.
-            exit cleartabs
+        case ('#')
+          iscomment = .true.
+          exit cleartabs
+        case ('!')
+          iscomment = .true.
+          exit cleartabs
+        case (tab)
+          line(1:1) = ' '
+          cycle cleartabs
+        case default
+          if (line(1:2) == comment) iscomment = .true.
+          if (len_trim(line) < 1) iscomment = .true.
+          exit cleartabs
         end select
       end do cleartabs
       !
-      if (.not.iscomment) then
+      if (.not. iscomment) then
         exit pcomments
       else
         if (iout > 0) then
           !find the last non-blank character.
-          l=len(line)
+          l = len(line)
           do i = l, 1, -1
-            if(line(i:i).ne.' ') then
+            if (line(i:i) /= ' ') then
               exit
             end if
           end do
-          !print the line up to the last non-blank character.
-          write(iout,'(1x,a)') line(1:i)
+          ! -- print the line up to the last non-blank character.
+          write (iout, '(1x,a)') line(1:i)
         end if
       end if
     end do pcomments
+    !
+    ! -- Return
     return
   end subroutine u9rdcom
 
+  !> @brief Read an unlimited length line from unit number lun into a deferred-
+  !! length character string (line).
+  !!
+  !! Tack on a single space to the end so that routines like URWORD continue to
+  !! function as before.
+  !<
   subroutine get_line(lun, line, iostat)
-! ******************************************************************************
-! Read an unlimited length line from unit number lun into a deferred-length
-! character string (line).  Tack on a single space to the end so that 
-! routines like URWORD continue to function as before.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- dummy variables
+    ! -- dummy
     integer(I4B), intent(in) :: lun
     character(len=:), intent(out), allocatable :: line
     integer(I4B), intent(out) :: iostat
-    ! -- local variables
+    ! -- local
     integer(I4B), parameter :: buffer_len = MAXCHARLEN
     character(len=buffer_len) :: buffer
     character(len=:), allocatable :: linetemp
     integer(I4B) :: size_read, linesize
-! ------------------------------------------------------------------------------
     !
     ! -- initialize
     line = ''
@@ -2226,36 +1945,33 @@ subroutine get_line(lun, line, iostat)
     !
     ! -- process
     do
-      read ( lun, '(A)',  &
-          iostat = iostat,  &
-          advance = 'no',  &
-          size = size_read ) buffer
+      read (lun, '(A)', iostat=iostat, advance='no', size=size_read) buffer
       if (is_iostat_eor(iostat)) then
         linesize = len(line)
-        deallocate(linetemp)
-        allocate(character(len=linesize) :: linetemp)
+        deallocate (linetemp)
+        allocate (character(len=linesize) :: linetemp)
         linetemp(:) = line(:)
-        deallocate(line)
-        allocate(character(len=linesize + size_read + 1) :: line)
+        deallocate (line)
+        allocate (character(len=linesize + size_read + 1) :: line)
         line(:) = linetemp(:)
-        line(linesize+1:) = buffer(:size_read)
+        line(linesize + 1:) = buffer(:size_read)
         linesize = len(line)
         line(linesize:linesize) = ' '
         iostat = 0
         exit
       else if (iostat == 0) then
         linesize = len(line)
-        deallocate(linetemp)
-        allocate(character(len=linesize) :: linetemp)
+        deallocate (linetemp)
+        allocate (character(len=linesize) :: linetemp)
         linetemp(:) = line(:)
-        deallocate(line)
-        allocate(character(len=linesize + size_read) :: line)
+        deallocate (line)
+        allocate (character(len=linesize + size_read) :: line)
         line(:) = linetemp(:)
-        line(linesize+1:) = buffer(:size_read)
+        line(linesize + 1:) = buffer(:size_read)
       else
         exit
       end if
     end do
-  end subroutine get_line  
+  end subroutine get_line
 
-END MODULE InputOutputModule
+end module InputOutputModule
diff --git a/src/Utilities/Iunit.f90 b/src/Utilities/Iunit.f90
index 0f109a0fe47..b1a7e949f2b 100644
--- a/src/Utilities/Iunit.f90
+++ b/src/Utilities/Iunit.f90
@@ -1,12 +1,14 @@
-! -- Module to manage unit numbers.  Allows for multiple unit numbers
-! -- assigned to a single package type, as shown below.
-! --    row(i)   cunit(i) iunit(i)%nval   iunit(i)%iunit  iunit(i)%ipos
-! --         1      BCF6              1           (1000)            (1)
-! --         2       WEL              3 (1001,1003,1005)        (2,5,7)
-! --         3       GHB              1           (1002)            (4)
-! --         4       EVT              2      (1004,1006)         (6,10)
-! --         5       RIV              0               ()             ()
-! --       ...
+!> @brief
+!! -- Module to manage unit numbers.  Allows for multiple unit numbers
+!! -- assigned to a single package type, as shown below.
+!! --    row(i)   cunit(i) iunit(i)%nval   iunit(i)%iunit  iunit(i)%ipos
+!! --         1      BCF6              1           (1000)            (1)
+!! --         2       WEL              3 (1001,1003,1005)        (2,5,7)
+!! --         3       GHB              1           (1002)            (4)
+!! --         4       EVT              2      (1004,1006)         (6,10)
+!! --         5       RIV              0               ()             ()
+!! --       ...
+!<
 
 module IunitModule
 
@@ -35,21 +37,16 @@ module IunitModule
 
 contains
 
+  !> @brief Allocate the cunit and iunit entries of this object, and copy cunit
+  !! into the object
+  !<
   subroutine init(this, niunit, cunit)
-! ******************************************************************************
-! init -- allocate the cunit and iunit entries of this object, and copy
-!   cunit into the object.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(IunitType), intent(inout) :: this
     integer(I4B), intent(in) :: niunit
     character(len=*), dimension(niunit), intent(in) :: cunit
     ! -- local
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     allocate (this%cunit(niunit))
     allocate (this%iunit(niunit))
@@ -62,15 +59,11 @@ subroutine init(this, niunit, cunit)
     return
   end subroutine init
 
+  !> @brief Add an ftyp and unit number
+  !!
+  !! Find the row for the ftyp and store another iunit value.
+  !<
   subroutine addfile(this, ftyp, iunit, ipos, namefilename)
-! ******************************************************************************
-! addfile -- add an ftyp and unit number.  Find the row for the ftyp and
-!            store another iunit value.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(IunitType), intent(inout) :: this
     character(len=*), intent(in) :: ftyp
@@ -81,7 +74,6 @@ subroutine addfile(this, ftyp, iunit, ipos, namefilename)
     character(len=LINELENGTH) :: errmsg
     integer(I4B), allocatable, dimension(:) :: itemp
     integer(I4B) :: i, irow
-! ------------------------------------------------------------------------------
     !
     ! -- Find the row containing ftyp
     irow = 0
@@ -104,7 +96,7 @@ subroutine addfile(this, ftyp, iunit, ipos, namefilename)
       this%iunit(irow)%nval = 1
     else
       !
-      ! -- increase size of iunit
+      ! -- Increase size of iunit
       allocate (itemp(this%iunit(irow)%nval))
       itemp(:) = this%iunit(irow)%iunit(:)
       deallocate (this%iunit(irow)%iunit)
@@ -112,13 +104,13 @@ subroutine addfile(this, ftyp, iunit, ipos, namefilename)
       allocate (this%iunit(irow)%iunit(this%iunit(irow)%nval))
       this%iunit(irow)%iunit(1:this%iunit(irow)%nval - 1) = itemp(:)
       !
-      ! -- increase size of ipos
+      ! -- Increase size of ipos
       itemp(:) = this%iunit(irow)%ipos(:)
       deallocate (this%iunit(irow)%ipos)
       allocate (this%iunit(irow)%ipos(this%iunit(irow)%nval))
       this%iunit(irow)%ipos(1:this%iunit(irow)%nval - 1) = itemp(:)
       !
-      ! -- cleanup temp
+      ! -- Cleanup temp
       deallocate (itemp)
     end if
     this%iunit(irow)%iunit(this%iunit(irow)%nval) = iunit
@@ -128,20 +120,18 @@ subroutine addfile(this, ftyp, iunit, ipos, namefilename)
     return
   end subroutine
 
+  !> @brief Get the last unit number for type ftyp or return 0 for iunit.
+  !!
+  !! If iremove is 1, then remove this unit number.  Similar to a list.pop().
+  !<
   subroutine getunitnumber(this, ftyp, iunit, iremove)
-! ******************************************************************************
-! Get the last unit number for type ftyp or return 0 for iunit.  If iremove
-! is 1, then remove this unit number.  Similar to a list.pop().
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     class(IunitType), intent(inout) :: this
     character(len=*), intent(in) :: ftyp
     integer(I4B), intent(inout) :: iunit
     integer(I4B), intent(in) :: iremove
+    ! -- local
     integer(I4B) :: i, irow, nval
-! ------------------------------------------------------------------------------
     !
     ! -- Find the row
     irow = 0
@@ -152,7 +142,7 @@ subroutine getunitnumber(this, ftyp, iunit, iremove)
       end if
     end do
     !
-    ! -- Find the unit number.
+    ! -- Find the unit number
     iunit = 0
     if (irow > 0) then
       nval = this%iunit(irow)%nval
diff --git a/src/Utilities/List.f90 b/src/Utilities/List.f90
index 1273359f0ce..70ac71dd502 100644
--- a/src/Utilities/List.f90
+++ b/src/Utilities/List.f90
@@ -1,12 +1,12 @@
 module ListModule
-  ! -- ListType implements a generic list.
   use KindModule, only: DP, I4B
+  use ErrorUtilModule, only: pstop
   use ConstantsModule, only: LINELENGTH
-  use GenericUtilitiesModule, only: sim_message, stop_with_error
   implicit none
   private
-  public :: ListType, ListNodeType, isEqualIface, arePointersEqual
+  public :: ListType, ListNodeType, isEqualIface
 
+  !> @brief A generic heterogeneous doubly-linked list.
   type :: ListType
     ! -- Public members
     type(ListNodeType), pointer, public :: firstNode => null()
@@ -65,8 +65,7 @@ function isEqualIface(obj1, obj2) result(isEqual)
 
 contains
 
-  ! -- Public type-bound procedures for ListType
-
+  !> @brief Append the given item to the list
   subroutine Add(this, objptr)
     ! -- dummy variables
     class(ListType), intent(inout) :: this
@@ -84,17 +83,10 @@ subroutine Add(this, objptr)
       this%lastNode => this%lastNode%nextNode
     end if
     this%nodeCount = this%nodeCount + 1
-    return
   end subroutine Add
 
+  !> @brief Deallocate all items in list
   subroutine Clear(this, destroy)
-    ! **************************************************************************
-    ! clear_list (finalizer)
-    ! Deallocate all items in linked list
-    ! **************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! --------------------------------------------------------------------------
     ! -- dummy variables
     class(ListType) :: this
     logical, intent(in), optional :: destroy
@@ -130,32 +122,21 @@ subroutine Clear(this, destroy)
     end do
     !
     call this%Reset()
-    !
-    return
+
   end subroutine Clear
 
+  !> @brief Return number of nodes in list
   function Count(this)
-    ! **************************************************************************
-    ! Count
-    ! Return number of nodes in linked list
-    ! **************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! --------------------------------------------------------------------------
-    ! -- return
     integer(I4B) :: Count
-    ! -- dummy variables
     class(ListType) :: this
-    !
     Count = this%nodeCount
-    !
-    return
   end function Count
 
+  !> @brief Determine whether the list contains the given object.
   function ContainsObject(this, obj, isEqual) result(hasObj)
     class(ListType), intent(inout) :: this
     class(*), pointer :: obj
-    procedure(isEqualIface), pointer, intent(in) :: isEqual
+    procedure(isEqualIface), pointer, intent(in), optional :: isEqual
     logical :: hasObj
     ! local
     type(ListNodeType), pointer :: current => null()
@@ -163,33 +144,26 @@ function ContainsObject(this, obj, isEqual) result(hasObj)
     hasObj = .false.
     current => this%firstNode
     do while (associated(current))
-      if (isEqual(current%Value, obj)) then
-        hasObj = .true.
-        return
+      if (present(isEqual)) then
+        if (isEqual(current%Value, obj)) then
+          hasObj = .true.
+          return
+        end if
+      else
+        if (associated(current%Value, obj)) then
+          hasObj = .true.
+          return
+        end if
       end if
 
       ! -- Advance to the next node
       current => current%nextNode
     end do
 
-    ! this means there is no match
-    return
   end function
 
-  function arePointersEqual(obj1, obj2) result(areIdentical)
-    class(*), pointer :: obj1, obj2
-    logical :: areIdentical
-    areIdentical = associated(obj1, obj2)
-  end function arePointersEqual
-
+  !> @brief Deallocate fromNode and all previous nodes, and reassign firstNode.
   subroutine DeallocateBackward(this, fromNode)
-    ! **************************************************************************
-    ! DeallocateBackward
-    ! Deallocate fromNode and all previous nodes in list; reassign firstNode.
-    ! **************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! --------------------------------------------------------------------------
     ! -- dummy
     class(ListType), target, intent(inout) :: this
     type(ListNodeType), pointer, intent(inout) :: fromNode
@@ -215,10 +189,10 @@ subroutine DeallocateBackward(this, fromNode)
       end do
       fromNode => null()
     end if
-    !
-    return
+
   end subroutine DeallocateBackward
 
+  !> @brief Get the index of the given item in the list.
   function GetIndex(this, obj) result(idx)
     class(ListType), target, intent(inout) :: this
     class(*), pointer :: obj
@@ -238,33 +212,29 @@ function GetIndex(this, obj) result(idx)
 
   end function GetIndex
 
+  !> @brief Get the next item in the list
   function GetNextItem(this) result(resultobj)
     class(ListType), target, intent(inout) :: this
-    ! result
     class(*), pointer :: resultobj
-    !
     call this%Next()
     resultobj => this%get_current_item()
-    return
   end function GetNextItem
 
+  !> @brief Get the previous item in the list
   function GetPreviousItem(this) result(resultobj)
     class(ListType), target, intent(inout) :: this
-    ! result
     class(*), pointer :: resultobj
-    !
     call this%Previous()
     resultobj => this%get_current_item()
-    return
   end function GetPreviousItem
 
+  !> @brief Insert the given item after the given index.
   subroutine InsertAfter(this, objptr, indx)
     ! -- dummy
     class(ListType), intent(inout) :: this
     class(*), pointer, intent(inout) :: objptr
     integer(I4B), intent(in) :: indx
     ! -- local
-    character(len=LINELENGTH) :: line
     integer(I4B) :: numnodes
     type(ListNodeType), pointer :: precedingNode => null()
     type(ListNodeType), pointer :: followingNode => null()
@@ -285,17 +255,14 @@ subroutine InsertAfter(this, objptr, indx)
         followingNode%prevNode => newNode
         this%nodeCount = this%nodeCount + 1
       else
-        write (line, '(a)') 'Programming error in ListType%insert_after'
-        call sim_message(line)
-        call stop_with_error(1)
+        call pstop(1, 'Programming error in ListType%insert_after')
       end if
     end if
-    !
-    return
+
   end subroutine InsertAfter
 
+  !> @brief Insert the given item before the given node.
   subroutine InsertBefore(this, objptr, targetNode)
-    ! Insert an object into the list in front of a target node
     ! -- dummy
     class(ListType), intent(inout) :: this
     class(*), pointer, intent(inout) :: objptr
@@ -303,9 +270,8 @@ subroutine InsertBefore(this, objptr, targetNode)
     ! -- local
     type(ListNodeType), pointer :: newNode => null()
     !
-    if (.not. associated(targetNode)) then
-      stop 'Programming error, likely in call to ListType%InsertBefore'
-    end if
+    if (.not. associated(targetNode)) &
+      call pstop(1, 'Programming error in ListType%InsertBefore')
     !
     ! Allocate a new list node and point its Value member to the object
     allocate (newNode)
@@ -324,13 +290,13 @@ subroutine InsertBefore(this, objptr, targetNode)
     end if
     targetNode%prevNode => newNode
     this%nodeCount = this%nodeCount + 1
-    !
-    return
+
   end subroutine InsertBefore
 
+  !> @brief Move the list's current node pointer and index one node forwards.
   subroutine Next(this)
     class(ListType), target, intent(inout) :: this
-    !
+
     if (this%currentNodeIndex == 0) then
       if (associated(this%firstNode)) then
         this%currentNode => this%firstNode
@@ -348,29 +314,27 @@ subroutine Next(this)
         this%currentNodeIndex = 0
       end if
     end if
-    return
   end subroutine Next
 
+  !> @brief Move the list's current node pointer and index one node backwards.
   subroutine Previous(this)
     class(ListType), target, intent(inout) :: this
-    !
     if (this%currentNodeIndex <= 1) then
       call this%Reset()
     else
       this%currentNode => this%currentNode%prevNode
       this%currentNodeIndex = this%currentNodeIndex - 1
     end if
-    return
   end subroutine Previous
 
+  !> @brief Reset the list's current node pointer and index.
   subroutine Reset(this)
     class(ListType), target, intent(inout) :: this
-    !
     this%currentNode => null()
     this%currentNodeIndex = 0
-    return
   end subroutine Reset
 
+  !> @brief Remove the node at the given index, optionally destroying its value.
   subroutine remove_node_by_index(this, i, destroyValue)
     ! -- dummy
     class(ListType), intent(inout) :: this
@@ -384,10 +348,10 @@ subroutine remove_node_by_index(this, i, destroyValue)
     if (associated(node)) then
       call this%remove_this_node(node, destroyValue)
     end if
-    !
-    return
+
   end subroutine remove_node_by_index
 
+  !> @brief Remove the given node, optionally destroying its value.
   subroutine remove_this_node(this, node, destroyValue)
     ! -- dummy
     class(ListType), intent(inout) :: this
@@ -432,12 +396,12 @@ subroutine remove_this_node(this, node, destroyValue)
       end if
       call this%Reset()
     end if
-    !
-    return
+
   end subroutine remove_this_node
 
   ! -- Private type-bound procedures for ListType
 
+  !> @brief Get a pointer to the item at the current node.
   function get_current_item(this) result(resultobj)
     class(ListType), target, intent(inout) :: this
     ! result
@@ -447,17 +411,10 @@ function get_current_item(this) result(resultobj)
     if (associated(this%currentNode)) then
       resultobj => this%currentNode%Value
     end if
-    return
   end function get_current_item
 
+  !> @brief Get a pointer to the item at the given index.
   function get_item_by_index(this, indx) result(resultobj)
-    ! **************************************************************************
-    ! get_item_by_index (implements GetItem)
-    ! Return object stored in ListNodeType%Value by index in list
-    ! **************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! --------------------------------------------------------------------------
     ! -- dummy
     class(ListType), intent(inout) :: this
     integer(I4B), intent(in) :: indx
@@ -511,17 +468,10 @@ function get_item_by_index(this, indx) result(resultobj)
         return
       end if
     end do
-    return
   end function get_item_by_index
 
+  !> @brief Get the node at the given index
   function get_node_by_index(this, indx) result(resultnode)
-    ! **************************************************************************
-    ! get_item_by_index (implements GetItem)
-    ! Return object stored in ListNodeType%Value by index in list
-    ! **************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! --------------------------------------------------------------------------
     ! -- dummy
     class(ListType), intent(inout) :: this
     integer(I4B), intent(in) :: indx
@@ -572,36 +522,22 @@ function get_node_by_index(this, indx) result(resultnode)
         return
       end if
     end do
-    return
   end function get_node_by_index
 
   ! -- Type-bound procedures for ListNodeType
 
+  !> @brief Return a pointer to this node's value.
   function GetItem(this) result(valueObject)
-    ! ************************************************************************
-    ! Perform a pointer assignment of valueObject to the contents of
-    ! this%Value
-    ! ************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------
     class(ListNodeType), intent(inout) :: this
     class(*), pointer :: valueObject
-    !
     valueObject => this%Value
-    return
   end function GetItem
 
+  !> @brief Nullify (optionally deallocating) this node's value.
   subroutine DeallocValue(this, destroy)
-    ! ************************************************************************
-    ! Deallocate whatever is stored in the Value component of this node.
-    ! ************************************************************************
-    !
-    !    SPECIFICATIONS:
-    ! ------------------------------------------------------------------------
     class(ListNodeType), intent(inout) :: this
     logical, intent(in), optional :: destroy
-    !
+
     if (associated(this%Value)) then
       if (present(destroy)) then
         if (destroy) then
@@ -610,7 +546,6 @@ subroutine DeallocValue(this, destroy)
       end if
       nullify (this%Value)
     end if
-    return
   end subroutine DeallocValue
 
 end module ListModule
diff --git a/src/Utilities/ListReader.f90 b/src/Utilities/ListReader.f90
index 99177280d38..db38583f1b5 100644
--- a/src/Utilities/ListReader.f90
+++ b/src/Utilities/ListReader.f90
@@ -6,6 +6,8 @@ module ListReaderModule
                              LENAUXNAME, LENLISTLABEL, DONE
   use SimVariablesModule, only: errmsg
   use SimModule, only: store_error, count_errors, store_error_unit
+  use LongLineReaderModule, only: LongLineReaderType
+  use GeomUtilModule, only: get_ijk, get_jk, get_node
 
   implicit none
   private
@@ -41,6 +43,7 @@ module ListReaderModule
     integer(I4B), dimension(:), allocatable :: idxtxtauxcol ! col locations of text in auxvar
     character(len=LENTIMESERIESNAME), dimension(:), allocatable :: txtrlist ! text found in rlist
     character(len=LENTIMESERIESNAME), dimension(:), allocatable :: txtauxvar ! text found in auxvar
+    type(LongLineReaderType), pointer :: line_reader => null()
   contains
     procedure :: read_list
     procedure :: write_list
@@ -53,8 +56,9 @@ module ListReaderModule
 
 contains
 
-  subroutine read_list(this, in, iout, nlist, inamedbound, mshape, nodelist, &
-                       rlist, auxvar, auxname, boundname, label)
+  subroutine read_list(this, line_reader, in, iout, nlist, inamedbound, &
+                       mshape, nodelist, rlist, auxvar, auxname, boundname, &
+                       label)
 ! ******************************************************************************
 ! init -- Initialize the reader
 ! ******************************************************************************
@@ -65,6 +69,7 @@ subroutine read_list(this, in, iout, nlist, inamedbound, mshape, nodelist, &
     use ConstantsModule, only: LENBOUNDNAME
     ! -- dummy
     class(ListReaderType) :: this
+    type(LongLineReaderType), intent(inout), target :: line_reader
     integer(I4B), intent(in) :: in
     integer(I4B), intent(in) :: iout
     integer(I4B), intent(inout) :: nlist
@@ -95,6 +100,7 @@ subroutine read_list(this, in, iout, nlist, inamedbound, mshape, nodelist, &
     this%auxvar => auxvar
     this%auxname => auxname
     this%boundname => boundname
+    this%line_reader => line_reader
     !
     ! -- Allocate arrays for storing text and text locations
     if (.not. allocated(this%idxtxtrow)) allocate (this%idxtxtrow(0))
@@ -125,7 +131,7 @@ subroutine read_control_record(this)
 !    SPECIFICATIONS:
 ! ------------------------------------------------------------------------------
     ! -- modules
-    use InputOutputModule, only: u9rdcom, urword
+    use InputOutputModule, only: urword
     ! -- dummy
     class(ListReaderType) :: this
     ! -- local
@@ -142,7 +148,7 @@ subroutine read_control_record(this)
     this%ibinary = 0
     !
     ! -- Read to the first non-commented line
-    call u9rdcom(this%in, this%iout, this%line, this%ierr)
+    call this%line_reader%rdcom(this%in, this%iout, this%line, this%ierr)
     this%lloc = 1
     call urword(this%line, this%lloc, this%istart, this%istop, 1, idum, r, &
                 this%iout, this%in)
@@ -167,7 +173,7 @@ subroutine set_openclose(this)
 !    SPECIFICATIONS:
 ! ------------------------------------------------------------------------------
     ! -- modules
-    use InputOutputModule, only: u9rdcom, urword, openfile
+    use InputOutputModule, only: urword, openfile
     use OpenSpecModule, only: form, access
     use ConstantsModule, only: LINELENGTH
     ! -- dummy
@@ -237,8 +243,9 @@ subroutine set_openclose(this)
     !
     ! -- Read the first line from inlist to be consistent with how the list is
     !    read when it is included in the package input file
-    if (this%ibinary /= 1) call u9rdcom(this%inlist, this%iout, this%line, &
-                                        this%ierr)
+    if (this%ibinary /= 1) &
+      call this%line_reader%rdcom(this%inlist, this%iout, this%line, &
+                                  this%ierr)
     !
     ! -- return
     return
@@ -282,7 +289,6 @@ subroutine read_binary(this)
 ! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LINELENGTH, LENBIGLINE
-    use InputOutputModule, only: get_node
     ! -- dummy
     class(ListReaderType) :: this
     ! -- local
@@ -314,14 +320,14 @@ subroutine read_binary(this)
       !
       ! -- read layer, row, col, or cell number
       read (this%inlist, iostat=this%ierr) cellid
-
-      ! -- ensure cellid is valid, store an error otherwise
-      call check_cellid(ii, cellid, this%mshape, this%ndim)
-
+      !
       ! -- If not end of record, then store nodenumber, else
       !    calculate lstend and nlist, and exit readloop
       select case (this%ierr)
       case (0)
+        !
+        ! -- ensure cellid is valid, store an error otherwise
+        call check_cellid(ii, cellid, this%mshape, this%ndim)
         !
         ! -- Check range
         if (ii > mxlist) then
@@ -394,7 +400,7 @@ subroutine read_ascii(this)
 ! ------------------------------------------------------------------------------
     ! -- modules
     use ConstantsModule, only: LENBOUNDNAME, LINELENGTH, DZERO
-    use InputOutputModule, only: u9rdcom, urword, get_node
+    use InputOutputModule, only: urword
     use ArrayHandlersModule, only: ExpandArray
     use TdisModule, only: kper
     ! -- dummy
@@ -427,7 +433,8 @@ subroutine read_ascii(this)
     readloop: do
       !
       ! -- First line was already read, so don't read again
-      if (ii /= 1) call u9rdcom(this%inlist, 0, this%line, this%ierr)
+      if (ii /= 1) &
+        call this%line_reader%rdcom(this%inlist, 0, this%line, this%ierr)
       !
       ! -- If this is an unknown-length list, then check for END.
       !    If found, then backspace, set nlist, and exit readloop.
@@ -436,10 +443,10 @@ subroutine read_ascii(this)
         call urword(this%line, this%lloc, this%istart, this%istop, 1, idum, r, &
                     this%iout, this%inlist)
         if (this%line(this%istart:this%istop) == 'END' .or. this%ierr < 0) then
-          ! If ierr < 0, backspace was already performed in u9rdcom, so only
-          ! need to backspace if END was found.
+          ! If END was found then call line_reader backspace
+          ! emulator so that caller can proceed with reading END.
           if (this%ierr == 0) then
-            backspace (this%inlist)
+            call this%line_reader%bkspc(this%inlist)
           end if
           this%nlist = ii - 1
           exit readloop
@@ -629,7 +636,7 @@ subroutine write_list(this)
     ! -- modules
     use ConstantsModule, only: LINELENGTH, LENBOUNDNAME, &
                                TABLEFT, TABCENTER
-    use InputOutputModule, only: ulstlb, get_ijk
+    use InputOutputModule, only: ulstlb
     use TableModule, only: TableType, table_cr
     ! -- dummy
     class(ListReaderType) :: this
diff --git a/src/Utilities/LongLineReader.f90 b/src/Utilities/LongLineReader.f90
new file mode 100644
index 00000000000..bce57afd45d
--- /dev/null
+++ b/src/Utilities/LongLineReader.f90
@@ -0,0 +1,117 @@
+!> @brief This module contains the LongLineReaderType
+!!
+!! The LongLineReader is a utility for reading text lines
+!! from mf6 input files.  It calls u9rdcom (which calls
+!! get_line) to read the first non-commented line of an
+!! input file.  The LongLineReader can emulate the Fortran
+!! backspace command by calling the bkspc method, which stores
+!! the current line in last_line, and will return last_line
+!! upon the next call to rdcom.  The LongLineReader was
+!! implemented to replace all Fortran backspace calls, due
+!! to a bug in ifort and ifx that prevented the backspace
+!! command from working properly with non-advancing IO.
+!!
+!<
+module LongLineReaderModule
+
+  use, intrinsic :: iso_fortran_env, only: IOSTAT_END
+  use KindModule, only: I4B
+  use SimModule, only: store_error
+  use InputOutputModule, only: u9rdcom
+
+  implicit none
+
+  private
+  public :: LongLineReaderType
+
+  !> @brief LongLineReaderType
+  !!
+  !!  Object for reading input from mf6 input files
+  !!
+  !<
+  type :: LongLineReaderType
+
+    character(len=:), allocatable :: line
+    character(len=:), allocatable :: last_line
+    integer(I4B) :: nbackspace = 0
+    integer(I4B) :: iostat = 0
+    integer(I4B) :: last_unit = 0
+
+  contains
+
+    procedure :: bkspc
+    procedure :: rdcom
+
+  end type LongLineReaderType
+
+contains
+
+  !> @brief Return the first non-comment line
+  !!
+  !! Skip through any comments and return the first
+  !! non-commented line.  If an end of file was
+  !! encountered previously, then return a blank line.
+  !! If a backspace was called prior to this call,
+  !! then do not read a new line and return last_line
+  !! instead.
+  !!
+  !<
+  subroutine rdcom(this, iu, iout, line, ierr)
+    class(LongLineReaderType) :: this
+    integer(I4B), intent(in) :: iu
+    integer(I4B), intent(in) :: iout
+    character(len=:), intent(inout), allocatable :: line
+    integer(I4B), intent(inout) :: ierr
+
+    ierr = 0
+
+    ! If using this reader to read from a new file
+    ! then reset state
+    if (iu /= this%last_unit) then
+      this%nbackspace = 0
+      this%iostat = 0
+    end if
+
+    if (this%nbackspace == 1) then
+      ! If backspace was called, then return last line
+      if (allocated(line)) deallocate (line)
+      allocate (character(len=len(this%last_line) + 1) :: line)
+      line(:) = this%last_line(:)
+      this%nbackspace = 0
+    else
+      ! if end of file was reached previously, then return a
+      ! blank line and return ierr as IOSTAT_END
+      if (this%iostat == IOSTAT_END) then
+        line = ' '
+        ierr = IOSTAT_END
+      else
+        call u9rdcom(iu, iout, line, ierr)
+      end if
+      this%last_line = line
+      this%iostat = ierr
+    end if
+    this%last_unit = iu
+    return
+  end subroutine rdcom
+
+  !> @brief Emulate a Fortan backspace
+  !!
+  !!  Emulate a fortran backspace call by storing
+  !!  the current line in long_line
+  !!
+  !<
+  subroutine bkspc(this, iin)
+    class(LongLineReaderType) :: this
+    integer(I4B), intent(in) :: iin
+    if (this%nbackspace > 0) then
+      call store_error( &
+        "Programming error in LongLineReaderType%bkspc(). Backspace &
+        & called more than once for an open file.", &
+        terminate=.true.)
+    else
+      this%nbackspace = 1
+    end if
+    return
+  end subroutine bkspc
+
+end module LongLineReaderModule
diff --git a/src/Utilities/MathUtil.f90 b/src/Utilities/MathUtil.f90
new file mode 100644
index 00000000000..f53c1d3d21c
--- /dev/null
+++ b/src/Utilities/MathUtil.f90
@@ -0,0 +1,437 @@
+module MathUtilModule
+  use KindModule, only: DP, I4B, LGP
+  use ErrorUtilModule, only: pstop
+  use ConstantsModule, only: MAXCHARLEN, LENHUGELINE, &
+                             DZERO, DPREC, DSAME, &
+                             LINELENGTH, LENHUGELINE, VSUMMARY
+
+  implicit none
+  private
+  public :: f1d, is_close, mod_offset, zeroch, zeroin, zerotest
+
+  interface mod_offset
+    module procedure :: mod_offset_int, mod_offset_dbl
+  end interface mod_offset
+
+  interface
+    function f1d(x) result(fx)
+      import DP
+      real(DP), intent(in) :: x
+      real(DP) :: fx
+    end function
+  end interface
+
+contains
+
+  !> @brief Check if a real value is approximately equal to another.
+  !!
+  !! By default the determination is symmetric in a and b, as in
+  !! Python's math.isclose, with relative difference scaled by a
+  !! factor of the larger absolute value of a and b. The formula
+  !! is: abs(a - b) <= max(rtol * max(abs(a), abs(b)), atol).
+  !!
+  !! If symmetric is set to false the test is asymmetric in a and
+  !! b, with b taken to be the reference value, and the alternate
+  !! formula (abs(a - b) <= (atol + rtol * abs(b))) is used. This
+  !! is the approach taken by numpy.allclose.
+  !!
+  !! Defaults for rtol and atol are DSAME and DZERO, respectively.
+  !! If a or b are near 0 (especially if either is 0), an absolute
+  !! tolerance suitable for the particular case should be provided.
+  !! For a justification of a zero absolute tolerance default see:
+  !! https://peps.python.org/pep-0485/#absolute-tolerance-default
+  !<
+  pure logical function is_close(a, b, rtol, atol, symmetric)
+    ! dummy
+    real(DP), intent(in) :: a !< first real
+    real(DP), intent(in) :: b !< second real (reference value if asymmetric)
+    real(DP), intent(in), optional :: rtol !< relative tolerance (default=DSAME)
+    real(DP), intent(in), optional :: atol !< absolute tolerance (default=DZERO)
+    logical(LGP), intent(in), optional :: symmetric !< toggle (a)symmetric comparison
+    ! local
+    real(DP) :: lrtol, latol
+    logical(LGP) :: lsymmetric
+
+    ! check for exact equality
+    if (a == b) then
+      is_close = .true.
+      return
+    end if
+
+    ! process optional arguments
+    if (.not. present(rtol)) then
+      lrtol = DSAME
+    else
+      lrtol = rtol
+    end if
+    if (.not. present(atol)) then
+      latol = DZERO
+    else
+      latol = atol
+    end if
+    if (.not. present(symmetric)) then
+      lsymmetric = .true.
+    else
+      lsymmetric = symmetric
+    end if
+
+    if (lsymmetric) then
+      ! "weak" symmetric test, https://peps.python.org/pep-0485/#which-symmetric-test
+      is_close = abs(a - b) <= max(lrtol * max(abs(a), abs(b)), latol)
+    else
+      ! asymmetric, https://numpy.org/doc/stable/reference/generated/numpy.isclose.html
+      is_close = (abs(a - b) <= (latol + lrtol * abs(b)))
+    end if
+  end function is_close
+
+  !> @brief Modulo with offset for integer values.
+  pure function mod_offset_int(a, n, d) result(mo)
+    ! -- dummy
+    integer(I4B), intent(in) :: a !< dividend
+    integer(I4B), intent(in) :: n !< divisor
+    integer(I4B), intent(in), optional :: d !< offset
+    integer(I4B) :: mo
+    ! -- local
+    integer(I4B) :: ld
+
+    if (present(d)) then
+      ld = d
+    else
+      ld = 0
+    end if
+    mo = a - n * floor(real(a - ld) / n)
+  end function mod_offset_int
+
+  !> @brief Modulo with offset for double precision values.
+  pure function mod_offset_dbl(a, n, d) result(mo)
+    ! -- dummy
+    real(DP), intent(in) :: a !< dividend
+    real(DP), intent(in) :: n !< divisor
+    real(DP), intent(in), optional :: d !< offset
+    real(DP) :: mo
+    ! -- local
+    real(DP) :: ld
+
+    if (present(d)) then
+      ld = d
+    else
+      ld = 0
+    end if
+    mo = a - n * floor((a - ld) / n)
+  end function mod_offset_dbl
+
+  !> @brief Compute zeros on an interval using Chadrupatla's method
+  !!
+  !! A zero of the function f{x} is computed in the interval (x0, x1)
+  !! given tolerance epsa using Chandrupatla's method. FORTRAN code based
+  !! generally on pseudocode in Scherer, POJ (2013) "Computational Physics:
+  !! Simulation of Classical and Quantum Systems," 2nd ed., Springer, New York.
+  !!
+  !<
+  function zeroch(x0, x1, f, epsa) result(z)
+    ! -- dummy
+    real(DP) :: x0, x1
+    procedure(f1d), pointer, intent(in) :: f
+    real(DP) :: epsa
+    real(DP) :: z
+    ! -- local
+    real(DP) :: epsm
+    real(DP) :: a, b, c, t
+    real(DP) :: aminusb, cminusb
+    real(DP) :: fa, fb, fc, fm, ft
+    real(DP) :: faminusfb, fcminusfb
+    real(DP) :: phi, philo, phihi
+    real(DP) :: racb, rcab, rbca
+    real(DP) :: tol, tl, tlc
+    real(DP) :: xi, xm, xt
+
+    epsm = epsilon(x0)
+    b = x0
+    a = x1
+    c = x1
+    aminusb = a - b
+    fb = f(b)
+    fa = f(a)
+    fc = f(c)
+    t = 5d-1
+
+    do while (.true.)
+      ! xt = a + t*(b - a)
+      xt = a - t * aminusb
+      ft = f(xt)
+      if (sign(ft, fa) == ft) then
+        c = a
+        fc = fa
+        a = xt
+        fa = ft
+      else
+        c = b
+        b = a
+        a = xt
+        fc = fb
+        fb = fa
+        fa = ft
+      end if
+      aminusb = a - b
+      cminusb = c - b
+      faminusfb = fa - fb
+      fcminusfb = fc - fb
+      xm = a
+      fm = fa
+      if (dabs(fb) < dabs(fa)) then
+        xm = b
+        fm = fb
+      end if
+      tol = 2d0 * epsm * dabs(xm) + epsa
+      ! tl = tol/dabs(b - c)
+      tl = tol / dabs(cminusb)
+      if ((tl > 5d-1) .or. (fm == 0d0)) then
+        z = xm
+        return
+      end if
+      ! xi = (a - b)/(c - b)
+      xi = aminusb / cminusb
+      ! phi = (fa - fb)/(fc - fb)
+      phi = faminusfb / fcminusfb
+      philo = 1d0 - dsqrt(1d0 - xi)
+      phihi = dsqrt(xi)
+      if ((phi > philo) .and. (phi < phihi)) then
+        ! rab = fa/(fb - fa)
+        ! rab = -fa/faminusfb
+        ! rcb = fc/(fb - fc)
+        ! rcb = -fc/fcminusfb
+        ! rac = fa/(fc - fa)
+        ! rbc = fb/(fc - fb)
+        ! rbc = fb/fcminusfb
+        ! t = rab*rcb + rac*rbc*(c - a)/(b - a)
+        ! t = rab*rcb - rac*rbc*(c - a)/aminusb
+        racb = fa / fcminusfb
+        rcab = fc / faminusfb
+        rbca = fb / (fc - fa)
+        t = racb * (rcab - rbca * (c - a) / aminusb)
+        if (t < tl) then
+          t = tl
+        else
+          tlc = 1d0 - tl
+          if (t > tlc) then
+            t = tlc
+          end if
+        end if
+      else
+        t = 5d-1
+      end if
+      ! if (t < tl) t = tl
+      ! if (t > 1d0 - tl) t = 1d0 - tl
+    end do
+  end function
+
+  !> @brief Compute a zero of the function f(x) in the interval (x0, x1).
+  !!
+  !! A zero of the function  f(x)  is computed in the interval ax,bx.
+  !!
+  !! Input:
+  !!
+  !! ax     left endpoint of initial interval
+  !! bx     right endpoint of initial interval
+  !! f      function subprogram which evaluates f(x) for any x in
+  !!        the interval  ax,bx
+  !! tol    desired length of the interval of uncertainty of the
+  !!        final result (.ge.0.)
+  !!
+  !! Output:
+  !!
+  !! zeroin abscissa approximating a zero of  f  in the interval ax,bx
+  !!
+  !!     it is assumed  that   f(ax)   and   f(bx)   have  opposite  signs
+  !! this is checked, and an error message is printed if this is not
+  !! satisfied.   zeroin  returns a zero  x  in the given interval
+  !! ax,bx  to within a tolerance  4*macheps*abs(x)+tol, where macheps  is
+  !! the  relative machine precision defined as the smallest representable
+  !! number such that  1.+macheps .gt. 1.
+  !!     this function subprogram is a slightly  modified  translation  of
+  !! the algol 60 procedure  zero  given in  richard brent, algorithms for
+  !! minimization without derivatives, prentice-hall, inc. (1973).
+  !<
+  function zeroin(ax, bx, f, tol) result(z)
+    ! -- dummy
+    real(DP) :: ax, bx
+    procedure(f1d), pointer, intent(in) :: f
+    real(DP) :: tol
+    real(DP) :: z
+    ! -- local
+    real(DP) :: eps
+    real(DP) :: a, b, c, d, e, s, p, q
+    real(DP) :: fa, fb, fc, r, tol1, xm
+    logical(LGP) :: rs
+
+    eps = epsilon(ax)
+    tol1 = eps + 1.0d0
+
+    a = ax
+    b = bx
+    fa = f(a)
+    fb = f(b)
+
+    ! check that f(ax) and f(bx) have different signs
+    if (.not. ((fa .eq. 0.0d0 .or. fb .eq. 0.0d0) .or. &
+               (fa * (fb / dabs(fb)) .le. 0.0d0))) &
+      call pstop(1, 'f(ax) and f(bx) do not have different signs,')
+
+    rs = .true. ! var reset
+    do while (.true.)
+      if (rs) then
+        c = a
+        fc = fa
+        d = b - a
+        e = d
+      end if
+
+      if (.not. (dabs(fc) .ge. dabs(fb))) then
+        a = b
+        b = c
+        c = a
+        fa = fb
+        fb = fc
+        fc = fa
+      end if
+
+      tol1 = 2.0d0 * eps * dabs(b) + 0.5d0 * tol
+      xm = 0.5d0 * (c - b)
+      if ((dabs(xm) .le. tol1) .or. (fb .eq. 0.0d0)) then
+        z = b
+        return
+      end if
+
+      ! see if a bisection is forced
+      if ((dabs(e) .ge. tol1) .and. (dabs(fa) .gt. dabs(fb))) then
+        s = fb / fa
+        if (a .ne. c) then
+          ! inverse quadratic interpolation
+          q = fa / fc
+          r = fb / fc
+          p = s * (2.0d0 * xm * q * (q - r) - (b - a) * (r - 1.0d0))
+          q = (q - 1.0d0) * (r - 1.0d0) * (s - 1.0d0)
+        else
+          ! linear interpolation
+          p = 2.0d0 * xm * s
+          q = 1.0d0 - s
+        end if
+
+        if (p .le. 0.0d0) then
+          p = -p
+        else
+          q = -q
+        end if
+        s = e
+        e = d
+        if (((2.0d0 * p) .ge. (3.0d0 * xm * q - dabs(tol1 * q))) .or. &
+            (p .ge. dabs(0.5d0 * s * q))) then
+          d = xm
+          e = d
+        else
+          d = p / q
+        end if
+      else
+        d = xm
+        e = d
+      end if
+
+      a = b
+      fa = fb
+
+      if (dabs(d) .le. tol1) then
+        if (xm .le. 0.0d0) then
+          b = b - tol1
+        else
+          b = b + tol1
+        end if
+      else
+        b = b + d
+      end if
+
+      fb = f(b)
+      rs = (fb * (fc / dabs(fc))) .gt. 0.0d0
+    end do
+  end function zeroin
+
+  !> @brief Compute a zero of the function f(x) in the interval (x0, x1)
+  function zerotest(x0, x1, f, epsa) result(z)
+    ! -- dummy
+    real(DP) :: x0, x1
+    procedure(f1d), pointer, intent(in) :: f
+    real(DP) :: epsa
+    real(DP) :: z
+    ! -- local
+    real(DP) :: epsm
+    real(DP) :: ema, emb
+    real(DP) :: f0
+    real(DP) :: tol
+    real(DP) :: xa, xb, xl
+    real(DP) :: ya, yb, yl
+    logical(LGP) :: retainedxa, retainedxb
+
+    epsm = epsilon(x0)
+    f0 = f(x0)
+    if (f0 .eq. 0d0) then
+      z = x0
+      return
+    else if (f0 .lt. 0d0) then
+      ya = x0
+      yb = x1
+      xa = f0
+      xb = f(yb)
+    else
+      ya = x1
+      yb = x0
+      xa = f(ya)
+      xb = f0
+    end if
+    ema = 1d0
+    emb = 1d0
+    retainedxa = .false.
+    retainedxb = .false.
+
+    do while (.true.)
+      ! yl = ya - xa*(yb - ya)/(xb - xa)
+      yl = (ya * xb * emb - yb * xa * ema) / (xb * emb - xa * ema)
+      tol = 4d0 * epsm * dabs(yl) + epsa
+      if (dabs(yb - ya) .le. tol) then
+        z = yl
+        return
+      else
+        xl = f(yl)
+        if (xl .eq. 0d0) then
+          z = yl
+          return
+        else if (xl .gt. 0d0) then
+          if (retainedxa) then
+            ! ema = 1d0 - xl/xb
+            ! if (ema <= 0d0) ema = 5d-1
+            ema = 5d-1 ! kluge illinois
+          else
+            ema = 1d0
+          end if
+          emb = 1d0
+          yb = yl
+          xb = xl
+          retainedxa = .true.
+          retainedxb = .false.
+        else
+          if (retainedxb) then
+            ! emb = 1d0 - xl/xa
+            ! if (emb <= 0d0) emb = 5d-1
+            emb = 5d-1 ! kluge illinois
+          else
+            emb = 1d0
+          end if
+          ema = 1d0
+          ya = yl
+          xa = xl
+          retainedxa = .false.
+          retainedxb = .true.
+        end if
+      end if
+    end do
+  end function
+
+end module MathUtilModule
diff --git a/src/Utilities/Memory/MemoryHelper.f90 b/src/Utilities/Memory/MemoryHelper.f90
index 17b96a89947..7f0e3760a20 100644
--- a/src/Utilities/Memory/MemoryHelper.f90
+++ b/src/Utilities/Memory/MemoryHelper.f90
@@ -101,14 +101,16 @@ subroutine split_mem_path(mem_path, component, subcomponent)
     character(len=*), intent(in) :: mem_path !< path to the memory object
     character(len=LENCOMPONENTNAME), intent(out) :: component !< name of the component (solution, model, exchange)
     character(len=LENCOMPONENTNAME), intent(out) :: subcomponent !< name of the subcomponent (package)
-
     ! local
+    character(len=LENMEMPATH) :: local_mem_path
     integer(I4B) :: idx
 
-    idx = index(mem_path, memPathSeparator, back=.true.)
+    call strip_context_mem_path(mem_path, local_mem_path)
+
+    idx = index(local_mem_path, memPathSeparator, back=.true.)
     ! if the separator is found at the end of the string,
     ! the path is invalid:
-    if (idx == len(mem_path)) then
+    if (idx == len_trim(local_mem_path)) then
       write (errmsg, '(*(G0))') &
         'Fatal error in Memory Manager, cannot split invalid memory path: ', &
         mem_path
@@ -119,21 +121,64 @@ subroutine split_mem_path(mem_path, component, subcomponent)
 
     if (idx > 0) then
       ! when found:
-      component = mem_path(:idx - 1)
-      subcomponent = mem_path(idx + 1:)
+      component = local_mem_path(:idx - 1)
+      subcomponent = local_mem_path(idx + 1:)
     else
       ! when not found, there apparently is no subcomponent:
-      component = mem_path
+      component = local_mem_path(:LENCOMPONENTNAME)
       subcomponent = ''
     end if
 
-    ! remove context specifier if prepended to component
-    idx = index(component, memPathSeparator, back=.true.)
-    if (idx > 0 .and. component(1:2) == '__') then
-      component = component(idx + 1:)
+  end subroutine split_mem_path
+
+  !> @brief Return the context from the memory path
+  !!
+  !! NB: when there is no context in the memory path, a
+  !! empty character string is returned.
+  !<
+  function get_mem_path_context(mem_path) result(res)
+    character(len=*), intent(in) :: mem_path !< path to the memory object
+    character(len=LENMEMPATH) :: res !< memory path context
+    ! local
+    integer(I4B) :: idx
+
+    ! initialize the memory path context
+    res = ' '
+
+    if (mem_path(1:2) == '__') then
+      idx = index(mem_path, memPathSeparator)
+      if (idx > 0) then
+        res = mem_path(:idx)
+      end if
     end if
 
-  end subroutine split_mem_path
+    return
+
+  end function get_mem_path_context
+
+  !> @brief Remove the context from the memory path
+  !!
+  !! NB: when there is no context in the memory path, the
+  !! original memory path is returned.
+  !<
+  subroutine strip_context_mem_path(mem_path, mem_path_no_context)
+    character(len=*), intent(in) :: mem_path !< path to the memory object
+    character(len=LENMEMPATH), intent(inout) :: mem_path_no_context !< path to the memory object without the context
+    ! local
+    integer(I4B) :: idx
+    character(len=LENMEMPATH) :: context
+
+    ! initialize the local mem_path
+    mem_path_no_context = mem_path
+
+    context = get_mem_path_context(mem_path)
+
+    if (len_trim(context) > 0) then
+      idx = len_trim(context)
+      mem_path_no_context = mem_path(idx + 1:)
+    end if
+
+  end subroutine strip_context_mem_path
 
   !> @brief Generic routine to check the length of (parts of) the memory address
   !!
diff --git a/src/Utilities/Memory/MemoryManager.f90 b/src/Utilities/Memory/MemoryManager.f90
index 3f636210151..da17dabe6f4 100644
--- a/src/Utilities/Memory/MemoryManager.f90
+++ b/src/Utilities/Memory/MemoryManager.f90
@@ -4,15 +4,17 @@ module MemoryManagerModule
   use ConstantsModule, only: DZERO, DONE, &
                              DEM3, DEM6, DEM9, DEP3, DEP6, DEP9, &
                              LENMEMPATH, LENMEMSEPARATOR, LENVARNAME, &
-                             LENCOMPONENTNAME, LINELENGTH, LENMEMTYPE, &
-                             LENMEMADDRESS, TABSTRING, TABUCSTRING, &
+                             LENMEMADDRESS, LENCOMPONENTNAME, &
+                             LENMEMTYPE, LINELENGTH, &
+                             TABSTRING, TABUCSTRING, &
                              TABINTEGER, TABREAL, TABCENTER, TABLEFT, &
                              TABRIGHT
   use SimVariablesModule, only: errmsg
   use SimModule, only: store_error, count_errors
   use MemoryTypeModule, only: MemoryType
   use MemoryListModule, only: MemoryListType
-  use MemoryHelperModule, only: mem_check_length, split_mem_path
+  use MemoryHelperModule, only: mem_check_length, split_mem_path, &
+                                strip_context_mem_path, get_mem_path_context
   use TableModule, only: TableType, table_cr
   use CharacterStringModule, only: CharacterStringType
 
@@ -67,8 +69,10 @@ module MemoryManagerModule
   interface mem_checkin
     module procedure &
       checkin_int1d, &
+      checkin_int2d, &
       checkin_dbl1d, &
-      checkin_dbl2d
+      checkin_dbl2d, &
+      checkin_charstr1d
   end interface mem_checkin
 
   interface mem_reallocate
@@ -997,6 +1001,49 @@ subroutine checkin_int1d(aint, name, mem_path, name2, mem_path2)
     return
   end subroutine checkin_int1d
 
+  !> @brief Check in an existing 2d integer array with a new address (name + path)
+  !<
+  subroutine checkin_int2d(aint2d, name, mem_path, name2, mem_path2)
+    integer(I4B), dimension(:, :), pointer, contiguous, intent(inout) :: aint2d !< the existing 2d array
+    character(len=*), intent(in) :: name !< new variable name
+    character(len=*), intent(in) :: mem_path !< new path where variable is stored
+    character(len=*), intent(in) :: name2 !< existing variable name
+    character(len=*), intent(in) :: mem_path2 !< existing path where variable is stored
+    ! -- local
+    type(MemoryType), pointer :: mt
+    integer(I4B) :: ncol, nrow, isize
+    ! -- code
+    !
+    ! -- check the variable name length
+    call mem_check_length(name, LENVARNAME, "variable")
+    !
+    ! -- set isize
+    ncol = size(aint2d, dim=1)
+    nrow = size(aint2d, dim=2)
+    isize = ncol * nrow
+    !
+    ! -- allocate memory type
+    allocate (mt)
+    !
+    ! -- set memory type
+    mt%aint2d => aint2d
+    mt%isize = isize
+    mt%name = name
+    mt%path = mem_path
+    write (mt%memtype, "(a,' (',i0,',',i0,')')") 'INTEGER', ncol, nrow
+    !
+    ! -- set master information
+    mt%master = .false.
+    mt%mastername = name2
+    mt%masterPath = mem_path2
+    !
+    ! -- add memory type to the memory list
+    call memorylist%add(mt)
+    !
+    ! -- return
+    return
+  end subroutine checkin_int2d
+
   !> @brief Check in an existing 1d double precision array with a new address (name + path)
   !<
   subroutine checkin_dbl1d(adbl, name, mem_path, name2, mem_path2)
@@ -1082,6 +1129,50 @@ subroutine checkin_dbl2d(adbl2d, name, mem_path, name2, mem_path2)
     return
   end subroutine checkin_dbl2d
 
+  !> @brief Check in an existing 1d CharacterStringType array with a new address (name + path)
+  !<
+  subroutine checkin_charstr1d(acharstr1d, ilen, name, mem_path, name2, mem_path2)
+    type(CharacterStringType), dimension(:), &
+      pointer, contiguous, intent(inout) :: acharstr1d !< the existing array
+    integer(I4B), intent(in) :: ilen
+    character(len=*), intent(in) :: name !< new variable name
+    character(len=*), intent(in) :: mem_path !< new path where variable is stored
+    character(len=*), intent(in) :: name2 !< existing variable name
+    character(len=*), intent(in) :: mem_path2 !< existing path where variable is stored
+    ! --local
+    type(MemoryType), pointer :: mt
+    integer(I4B) :: isize
+    ! -- code
+    !
+    ! -- check variable name length
+    call mem_check_length(name, LENVARNAME, "variable")
+    !
+    ! -- set isize
+    isize = size(acharstr1d)
+    !
+    ! -- allocate memory type
+    allocate (mt)
+    !
+    ! -- set memory type
+    mt%acharstr1d => acharstr1d
+    mt%element_size = ilen
+    mt%isize = isize
+    mt%name = name
+    mt%path = mem_path
+    write (mt%memtype, "(a,' LEN=',i0,' (',i0,')')") 'STRING', ilen, isize
+    !
+    ! -- set master information
+    mt%master = .false.
+    mt%mastername = name2
+    mt%masterPath = mem_path2
+    !
+    ! -- add memory type to the memory list
+    call memorylist%add(mt)
+    !
+    ! -- return
+    return
+  end subroutine checkin_charstr1d
+
   !> @brief Reallocate a 1-dimensional defined length string array
   !<
   subroutine reallocate_str1d(astr, ilen, nrow, name, mem_path)
@@ -2658,7 +2749,7 @@ subroutine mem_summary_total(iout, bytes)
     !
     ! -- set table terms
     nterms = 2
-    nrows = 5
+    nrows = 6
     !
     ! -- set up table title
     title = 'MEMORY MANAGER TOTAL STORAGE BY DATA TYPE, IN '//trim(cunits)
@@ -2703,6 +2794,11 @@ subroutine mem_summary_total(iout, bytes)
     call memtab%add_term('Total')
     call memtab%add_term(smb)
     !
+    ! -- Virtual memory
+    smb = calc_virtual_mem() * fact
+    call memtab%add_term('Virtual')
+    call memtab%add_term(smb)
+    !
     ! -- deallocate table
     call mem_cleanup_table()
     !
@@ -2734,7 +2830,12 @@ subroutine mem_write_usage(iout)
     integer(I4B), intent(in) :: iout !< unit number for mfsim.lst
     ! -- local
     class(MemoryType), pointer :: mt
-    character(len=LENMEMPATH), allocatable, dimension(:) :: cunique
+    character(len=LENMEMADDRESS), allocatable, dimension(:) :: cunique
+    ! character(len=LENMEMPATH) :: mem_path
+    character(len=LENMEMPATH) :: context
+    character(len=LENCOMPONENTNAME) :: component
+    character(len=LENCOMPONENTNAME) :: subcomponent
+    character(len=LENMEMADDRESS) :: context_component
     character(LEN=10) :: cunits
     integer(I4B) :: ipos
     integer(I4B) :: icomp
@@ -2778,7 +2879,10 @@ subroutine mem_write_usage(iout)
         ilen = len_trim(cunique(icomp))
         do ipos = 1, memorylist%count()
           mt => memorylist%Get(ipos)
-          if (cunique(icomp) /= mt%path(1:ilen)) cycle
+          call split_mem_path(mt%path, component, subcomponent)
+          context = get_mem_path_context(mt%path)
+          context_component = trim(context)//component
+          if (cunique(icomp) /= context_component(1:ilen)) cycle
           if (.not. mt%master) cycle
           if (mt%memtype(1:6) == 'STRING') then
             nchars = nchars + mt%isize * mt%element_size
@@ -2833,6 +2937,24 @@ subroutine mem_print_detailed(iout)
 
   end subroutine mem_print_detailed
 
+  !> @brief Sum up virtual memory, i.e. memory
+  !< that is owned by other processes
+  function calc_virtual_mem() result(vmem_size)
+    real(DP) :: vmem_size
+    ! local
+    integer(I4B) :: i
+    type(MemoryType), pointer :: mt
+
+    vmem_size = DZERO
+    do i = 1, memorylist%count()
+      mt => memorylist%Get(i)
+      if (index(mt%path, "__P") == 1) then
+        vmem_size = mt%element_size * mt%isize + vmem_size
+      end if
+    end do
+
+  end function calc_virtual_mem
+
   !> @brief Deallocate memory in the memory manager
   !<
   subroutine mem_da()
@@ -2892,11 +3014,14 @@ subroutine mem_unique_origins(cunique)
     ! -- modules
     use ArrayHandlersModule, only: ExpandArray, ifind
     ! -- dummy
-    character(len=LENMEMPATH), allocatable, dimension(:), intent(inout) :: cunique !< array with unique first components
+    character(len=LENMEMADDRESS), allocatable, dimension(:), intent(inout) :: &
+      cunique !< array with unique first components
     ! -- local
     class(MemoryType), pointer :: mt
+    character(len=LENMEMPATH) :: context
     character(len=LENCOMPONENTNAME) :: component
     character(len=LENCOMPONENTNAME) :: subcomponent
+    character(len=LENMEMADDRESS) :: context_component
     integer(I4B) :: ipos
     integer(I4B) :: ipa
     ! -- code
@@ -2908,10 +3033,12 @@ subroutine mem_unique_origins(cunique)
     do ipos = 1, memorylist%count()
       mt => memorylist%Get(ipos)
       call split_mem_path(mt%path, component, subcomponent)
-      ipa = ifind(cunique, component)
+      context = get_mem_path_context(mt%path)
+      context_component = trim(context)//component
+      ipa = ifind(cunique, context_component)
       if (ipa < 1) then
         call ExpandArray(cunique, 1)
-        cunique(size(cunique)) = component
+        cunique(size(cunique)) = context_component
       end if
     end do
     !
diff --git a/src/Utilities/Memory/MemoryManagerExt.f90 b/src/Utilities/Memory/MemoryManagerExt.f90
index d169449466b..ded5862e4f5 100644
--- a/src/Utilities/Memory/MemoryManagerExt.f90
+++ b/src/Utilities/Memory/MemoryManagerExt.f90
@@ -16,7 +16,8 @@ module MemoryManagerExtModule
       mem_set_value_int1d, mem_set_value_int1d_mapped, &
       mem_set_value_int2d, mem_set_value_int3d, mem_set_value_dbl, &
       mem_set_value_dbl1d, mem_set_value_dbl1d_mapped, &
-      mem_set_value_dbl2d, mem_set_value_dbl3d, mem_set_value_str
+      mem_set_value_dbl2d, mem_set_value_dbl3d, mem_set_value_str, &
+      mem_set_value_charstr1d
   end interface mem_set_value
 
 contains
@@ -41,8 +42,6 @@ subroutine memorylist_remove(component, subcomponent, context)
         mt => memorylist%Get(ipos)
         if (mt%path == memory_path .and. mt%mt_associated()) then
           call mt%mt_deallocate()
-          deallocate (mt)
-          call memorylist%remove(ipos, .false.)
           removed = .true.
           exit
         end if
@@ -61,8 +60,12 @@ subroutine mem_set_value_logical(p_mem, varname, memory_path, found)
     logical(LGP) :: checkfail = .false.
 
     call get_from_memorylist(varname, memory_path, mt, found, checkfail)
-    if (found .and. mt%memtype(1:index(mt%memtype, ' ')) == 'LOGICAL') then
-      p_mem = mt%logicalsclr
+    if (found .and. mt%memtype(1:index(mt%memtype, ' ')) == 'INTEGER') then
+      if (mt%intsclr == 0) then
+        p_mem = .false.
+      else
+        p_mem = .true.
+      end if
     end if
   end subroutine mem_set_value_logical
 
@@ -366,4 +369,23 @@ subroutine mem_set_value_str(p_mem, varname, memory_path, found)
     end if
   end subroutine mem_set_value_str
 
+  subroutine mem_set_value_charstr1d(p_mem, varname, memory_path, found)
+    use CharacterStringModule, only: CharacterStringType
+    type(CharacterStringType), dimension(:), &
+      pointer, contiguous, intent(inout) :: p_mem !< pointer to charstr 1d array
+    character(len=*), intent(in) :: varname !< variable name
+    character(len=*), intent(in) :: memory_path !< path where variable is stored
+    logical(LGP), intent(inout) :: found
+    type(MemoryType), pointer :: mt
+    logical(LGP) :: checkfail = .false.
+    integer(I4B) :: n
+
+    call get_from_memorylist(varname, memory_path, mt, found, checkfail)
+    if (found .and. mt%memtype(1:index(mt%memtype, ' ')) == 'STRING') then
+      do n = 1, size(mt%acharstr1d)
+        p_mem(n) = mt%acharstr1d(n)
+      end do
+    end if
+  end subroutine mem_set_value_charstr1d
+
 end module MemoryManagerExtModule
diff --git a/src/Utilities/Message.f90 b/src/Utilities/Message.f90
index c4f40740dcb..1e97db078fb 100644
--- a/src/Utilities/Message.f90
+++ b/src/Utilities/Message.f90
@@ -1,266 +1,481 @@
-!> @brief This module contains message methods
-!!
-!! This module contains generic message methods that are used to
-!! create warning and error messages and notes. This module also has methods
-!! for counting messages. The module does not have any dependencies on
-!! models, exchanges, or solutions in a simulation.
-!!
-!<
+!> @brief Store and issue logging messages to output units.
 module MessageModule
 
   use KindModule, only: LGP, I4B, DP
   use ConstantsModule, only: LINELENGTH, MAXCHARLEN, DONE, &
-                             VSUMMARY
-  use GenericUtilitiesModule, only: sim_message, write_message
-  use SimVariablesModule, only: istdout
+                             VSUMMARY, LENHUGELINE
   use ArrayHandlersModule, only: ExpandArray
+  use SimVariablesModule, only: istdout
 
   implicit none
+  public :: MessagesType
+  public :: write_message
+  public :: write_message_counter
+  public :: write_message_centered
 
-  public :: MessageType
-
-  type :: MessageType
-
-    character(len=LINELENGTH) :: title !< title of the message
-    character(len=LINELENGTH) :: name !< message name
-    integer(I4B) :: nmessage = 0 !< number of messages stored
-    integer(I4B) :: max_message = 1000 !< default maximum number of messages that can be stored
-    integer(I4B) :: max_exceeded = 0 !< flag indicating if the maximum number of messages has exceed the maximum number
-    integer(I4B) :: inc_message = 100 !< amount to increment message array by when calling ExpandArray
-    character(len=MAXCHARLEN), allocatable, dimension(:) :: message !< message array
-
+  !> @brief Container for related messages.
+  !!
+  !! A maximum capacity can be configured. Message storage
+  !! is dynamically resized up to the configured capacity.
+  !<
+  type :: MessagesType
+    integer(I4B) :: num_messages = 0 !< number of messages currently stored
+    integer(I4B) :: max_messages = 1000 !< default max message storage capacity
+    integer(I4B) :: max_exceeded = 0 !< number of messages in excess of maximum
+    integer(I4B) :: exp_messages = 100 !< number of slots to expand message array
+    character(len=MAXCHARLEN), allocatable, dimension(:) :: messages !< message array
   contains
-
-    procedure :: init_message
-    procedure :: count_message
-    procedure :: set_max_message
-    procedure :: store_message
-    procedure :: print_message
-    procedure :: deallocate_message
-
-  end type MessageType
+    procedure :: init
+    procedure :: count
+    procedure :: set_max
+    procedure :: store
+    procedure :: write_all
+    procedure :: deallocate
+  end type MessagesType
 
 contains
 
-  !> @brief Always initialize the message object
-    !!
-    !! Subroutine that initializes the message object. Allocation of message
-    !! array occurs on-the-fly.
-    !!
-  !<
-  subroutine init_message(this)
-    ! -- dummy variables
-    class(MessageType) :: this !< MessageType object
-    !
-    ! -- initialize message variables
-    this%nmessage = 0
-    this%max_message = 1000
+  !> @brief Initialize message storage.
+  subroutine init(this)
+    class(MessagesType) :: this !< MessageType object
+
+    this%num_messages = 0
+    this%max_messages = 1000
     this%max_exceeded = 0
-    this%inc_message = 100
-    !
-    ! -- return
-    return
-  end subroutine init_message
-
-  !> @brief Return number of messages
-    !!
-    !!  Function to return the number of messages that have been stored.
-    !!
-    !!  @return  ncount number of messages stored
-    !!
-  !<
-  function count_message(this) result(nmessage)
-    ! -- dummy variables
-    class(MessageType) :: this !< MessageType object
-    ! -- return variable
+    this%exp_messages = 100
+  end subroutine init
+
+  !> @brief Return the number of messages currently stored.
+  function count(this) result(nmessage)
+    class(MessagesType) :: this !< MessageType object
     integer(I4B) :: nmessage
-    !
-    ! -- set nmessage
-    if (allocated(this%message)) then
-      nmessage = this%nmessage
+
+    if (allocated(this%messages)) then
+      nmessage = this%num_messages
     else
       nmessage = 0
     end if
-    !
-    ! -- return
-    return
-  end function count_message
-
-  !> @brief Set the maximum number of messages stored
-    !!
-    !!  Subroutine to set the maximum number of messages that will be stored
-    !!  in a simulation.
-    !!
-  !<
-  subroutine set_max_message(this, imax)
-    ! -- dummy variables
-    class(MessageType) :: this !< MessageType object
+  end function count
+
+  !> @brief Set the maximum number of messages.
+  subroutine set_max(this, imax)
+    class(MessagesType) :: this !< MessageType object
     integer(I4B), intent(in) :: imax !< maximum number of messages that will be stored
-    !
-    ! -- set max_message
-    this%max_message = imax
-    !
-    ! -- return
-    return
-  end subroutine set_max_message
-
-  !> @brief Store message
-    !!
-    !!  Subroutine to store a message for printing at the end of
-    !!  the simulation.
-    !!
+
+    this%max_messages = imax
+  end subroutine set_max
+
+  !> @brief Add a message to storage.
+  !!
+  !! An optional string may be provided to filter out duplicate messages.
+  !! If any stored messages contain the string the message is not stored.
   !<
-  subroutine store_message(this, msg, substring)
+  subroutine store(this, msg, substring)
     ! -- dummy variables
-    class(MessageType) :: this !< MessageType object
+    class(MessagesType) :: this !< MessageType object
     character(len=*), intent(in) :: msg !< message
-    character(len=*), intent(in), optional :: substring !< optional string that can be used
-                                                        !! to prevent storing duplicate messages
+    character(len=*), intent(in), optional :: substring !< duplicate pattern
     ! -- local variables
     logical(LGP) :: inc_array
-    logical(LGP) :: increment_message
-    integer(I4B) :: i
-    integer(I4B) :: idx
-    !
-    ! -- determine if messages should be expanded
-    inc_array = .TRUE.
-    if (allocated(this%message)) then
-      i = this%nmessage
-      if (i < size(this%message)) then
-        inc_array = .FALSE.
+    integer(I4B) :: i, n
+
+    ! -- resize message array if needed
+    inc_array = .true.
+    if (allocated(this%messages)) then
+      if (this%num_messages < size(this%messages)) then
+        inc_array = .false.
       end if
     end if
-    !
-    ! -- resize message
     if (inc_array) then
-      call ExpandArray(this%message, increment=this%inc_message)
-      this%inc_message = int(this%inc_message * 1.1)
+      call ExpandArray(this%messages, increment=this%exp_messages)
+      this%exp_messages = int(this%exp_messages * 1.1)
     end if
-    !
-    ! -- Determine if the substring exists in the passed message.
-    !    If substring is in passed message, do not add the duplicate
-    !    passed message.
-    increment_message = .TRUE.
+
+    ! -- don't store duplicate messages
     if (present(substring)) then
-      do i = 1, this%nmessage
-        idx = index(this%message(i), substring)
-        if (idx > 0) then
-          increment_message = .FALSE.
-          exit
-        end if
+      do i = 1, this%num_messages
+        if (index(this%messages(i), substring) > 0) return
       end do
     end if
-    !
-    ! -- store this message and calculate nmessage
-    if (increment_message) then
-      i = this%nmessage + 1
-      if (i <= this%max_message) then
-        this%nmessage = i
-        this%message(i) = msg
-      else
-        this%max_exceeded = this%max_exceeded + 1
-      end if
+
+    ! -- store message and update count unless
+    !    at capacity, then update excess count
+    n = this%num_messages + 1
+    if (n <= this%max_messages) then
+      this%num_messages = n
+      this%messages(n) = msg
+    else
+      this%max_exceeded = this%max_exceeded + 1
     end if
-    !
-    ! -- return
-    return
-  end subroutine store_message
-
-  !> @brief Print messages
-    !!
-    !!  Subroutine to print stored messages.
-    !!
+  end subroutine store
+
+  !> @brief Write all stored messages to standard output.
+  !!
+  !! An optional title to precede the messages may be provided.
+  !! The title is printed on a separate line. An arbitrary kind
+  !! may be specified, e.g. 'note', 'warning' or 'error. A file
+  !! unit can also be specified to write in addition to stdout.
   !<
-  subroutine print_message(this, title, name, iunit, level)
+  subroutine write_all(this, title, kind, iunit)
     ! -- dummy variables
-    class(MessageType) :: this !< MessageType object
-    character(len=*), intent(in) :: title !< message title
-    character(len=*), intent(in) :: name !< message name
-    integer(I4B), intent(in), optional :: iunit !< optional file unit to save messages to
-    integer(I4B), intent(in), optional :: level !< optional level of messages to print
+    class(MessagesType) :: this !< MessageType object
+    character(len=*), intent(in), optional :: title !< message title
+    character(len=*), intent(in), optional :: kind !< message kind
+    integer(I4B), intent(in), optional :: iunit !< file unit
     ! -- local
+    character(len=LINELENGTH) :: ltitle
+    character(len=LINELENGTH) :: lkind
     character(len=LINELENGTH) :: errmsg
     character(len=LINELENGTH) :: cerr
     integer(I4B) :: iu
-    integer(I4B) :: ilevel
     integer(I4B) :: i
     integer(I4B) :: isize
     integer(I4B) :: iwidth
     ! -- formats
     character(len=*), parameter :: stdfmt = "(/,A,/)"
-    !
+
     ! -- process optional variables
+    if (present(title)) then
+      ltitle = title
+    else
+      ltitle = ''
+    end if
+    if (present(kind)) then
+      lkind = kind
+    else
+      lkind = ''
+    end if
     if (present(iunit)) then
       iu = iunit
     else
       iu = 0
     end if
-    if (present(level)) then
-      ilevel = level
-    else
-      ilevel = VSUMMARY
-    end if
-    !
-    ! -- write the title and all message entries
-    if (allocated(this%message)) then
-      isize = this%nmessage
+
+    ! -- write messages, if any
+    if (allocated(this%messages)) then
+      isize = this%num_messages
       if (isize > 0) then
-        !
         ! -- calculate the maximum width of the prepended string
         !    for the counter
         write (cerr, '(i0)') isize
         iwidth = len_trim(cerr) + 1
-        !
+
         ! -- write title for message
-        if (iu > 0) then
-          call sim_message(title, iunit=iu, fmt=stdfmt, level=ilevel)
+        if (trim(ltitle) /= '') then
+          if (iu > 0) &
+            call write_message(iunit=iu, text=ltitle, fmt=stdfmt)
+          call write_message(text=ltitle, fmt=stdfmt)
         end if
-        call sim_message(title, fmt=stdfmt, level=ilevel)
-        !
+
         ! -- write each message
         do i = 1, isize
-          call write_message(this%message(i), icount=i, iwidth=iwidth, &
-                             level=ilevel)
-          if (iu > 0) then
-            call write_message(this%message(i), icount=i, iwidth=iwidth, &
-                               iunit=iu, level=ilevel)
-          end if
+          if (iu > 0) &
+            call write_message_counter( &
+            iunit=iu, &
+            text=this%messages(i), &
+            icount=i, &
+            iwidth=iwidth)
+          call write_message_counter( &
+            text=this%messages(i), &
+            icount=i, &
+            iwidth=iwidth)
         end do
-        !
+
         ! -- write the number of additional messages
         if (this%max_exceeded > 0) then
           write (errmsg, '(i0,3(1x,a))') &
-            this%max_exceeded, 'additional', trim(name), &
+            this%max_exceeded, 'additional', trim(kind), &
             'detected but not printed.'
-          call sim_message(trim(errmsg), fmt='(/,1x,a)', level=ilevel)
-          if (iu > 0) then
-            call sim_message(trim(errmsg), iunit=iu, fmt='(/,1x,a)', &
-                             level=ilevel)
-          end if
+          if (iu > 0) &
+            call write_message(iunit=iu, text=trim(errmsg), fmt='(/,1x,a)')
+          call write_message(text=trim(errmsg), fmt='(/,1x,a)')
         end if
       end if
     end if
-    !
-    ! -- return
-    return
-  end subroutine print_message
+  end subroutine write_all
+
+  !> @ brief Deallocate message storage.
+  subroutine deallocate (this)
+    class(MessagesType) :: this
+    if (allocated(this%messages)) deallocate (this%messages)
+  end subroutine deallocate
 
-  !> @ brief Deallocate message
+  !> @brief Write a message to an output unit.
   !!
-  !! Subroutine that deallocate the array of strings if it was allocated
+  !! Use `advance` to toggle advancing output. Use `skipbefore/after` to
+  !! configure the number of whitespace lines before/after the message.
+  !<
+  subroutine write_message(text, iunit, fmt, &
+                           skipbefore, skipafter, advance)
+    ! -- dummy
+    character(len=*), intent(in) :: text !< message to write
+    integer(I4B), intent(in), optional :: iunit !< output unit to write the message to
+    character(len=*), intent(in), optional :: fmt !< format to write the message (default='(a)')
+    integer(I4B), intent(in), optional :: skipbefore !< number of empty lines before message (default=0)
+    integer(I4B), intent(in), optional :: skipafter !< number of empty lines after message (default=0)
+    logical(LGP), intent(in), optional :: advance !< whether to use advancing output (default is .true.)
+    ! -- local
+    character(len=3) :: cadvance
+    integer(I4B) :: i
+    integer(I4B) :: ilen
+    integer(I4B) :: iu
+    character(len=LENHUGELINE) :: simfmt
+    character(len=*), parameter :: stdfmt = '(a)'
+    character(len=*), parameter :: emptyfmt = '()'
+
+    if (present(iunit)) then
+      iu = iunit
+    else
+      iu = istdout
+    end if
+
+    ! -- get message length
+    ilen = len_trim(text)
+
+    ! -- process optional arguments
+    if (present(fmt)) then
+      simfmt = fmt
+    else
+      if (ilen > 0) then
+        simfmt = stdfmt
+      else
+        simfmt = emptyfmt
+      end if
+    end if
+    if (present(advance)) then
+      if (advance) then
+        cadvance = 'YES'
+      else
+        cadvance = 'NO'
+      end if
+    else
+      cadvance = 'YES'
+    end if
+
+    ! -- write empty line before message, if enabled
+    if (present(skipbefore)) then
+      do i = 1, skipbefore
+        write (iu, *)
+      end do
+    end if
+
+    ! -- write message if it isn't empty
+    if (ilen > 0) then
+      write (iu, trim(simfmt), advance=cadvance) text(1:ilen)
+    else
+      write (iu, trim(simfmt), advance=cadvance)
+    end if
+
+    ! -- write empty line after message, if enabled
+    if (present(skipafter)) then
+      do i = 1, skipafter
+        write (iu, *)
+      end do
+    end if
+  end subroutine write_message
+
+  !> @brief Write a message with configurable indentation and numbering.
   !!
+  !! The message may exceed 78 characters in length. Messages longer than
+  !! 78 characters are written across multiple lines. After icount lines,
+  !! subsequent lines are indented and numbered. Use skipbefore/after to
+  !! configure the number of empty lines before/after the message.
   !<
-  subroutine deallocate_message(this)
-    ! -- dummy variables
-    class(MessageType) :: this !< MessageType object
-    !
-    ! -- deallocate the message
-    if (allocated(this%message)) then
-      deallocate (this%message)
+  subroutine write_message_counter(text, iunit, icount, iwidth, &
+                                   skipbefore, skipafter)
+    ! -- dummy
+    character(len=*), intent(in) :: text !< message to be written
+    integer(I4B), intent(in), optional :: iunit !< the unit number to which the message is written
+    integer(I4B), intent(in), optional :: icount !< counter to prepended to the message
+    integer(I4B), intent(in), optional :: iwidth !< maximum width of the prepended counter
+    integer(I4B), intent(in), optional :: skipbefore !< optional number of empty lines before message (default=0)
+    integer(I4B), intent(in), optional :: skipafter !< optional number of empty lines after message (default=0)
+    ! -- local
+    integer(I4B), parameter :: len_line = 78
+    character(len=LENHUGELINE) :: amessage
+    character(len=len_line) :: line
+    character(len=16) :: cfmt
+    character(len=10) :: counter
+    character(len=5) :: fmt_first
+    character(len=20) :: fmt_cont
+    logical(LGP) :: include_counter
+    integer(I4B) :: isb
+    integer(I4B) :: isa
+    integer(I4B) :: jend
+    integer(I4B) :: len_str1
+    integer(I4B) :: len_str2
+    integer(I4B) :: len_message
+    integer(I4B) :: i
+    integer(I4B) :: j
+    integer(I4B) :: iu
+
+    if (present(iunit)) then
+      iu = iunit
+    else
+      iu = istdout
+    end if
+
+    ! -- abort if message is empty
+    if (len_trim(text) < 1) return
+
+    ! -- initialize local variables
+    amessage = text
+    counter = ''
+    fmt_first = '(A)'
+    fmt_cont = '(A)'
+    len_str1 = 0
+    len_str2 = len_line
+    include_counter = .false.
+    j = 0
+
+    ! -- process optional arguments
+    if (present(skipbefore)) then
+      isb = skipbefore
+    else
+      isb = 0
+    end if
+    if (present(skipafter)) then
+      isa = skipafter
+    else
+      isa = 0
+    end if
+
+    ! -- create the counter to prepend to the start of the message,
+    !    formats, and variables used to create strings
+    if (present(iwidth) .and. present(icount)) then
+      include_counter = .true.
+
+      ! -- write counter
+      write (cfmt, '(A,I0,A)') '(1x,i', iwidth, ',".",1x)'
+      write (counter, cfmt) icount
+
+      ! -- calculate the length of the first and second string on a line
+      len_str1 = len(trim(counter)) + 1
+      len_str2 = len_line - len_str1
+
+      ! -- write format for the continuation lines
+      write (fmt_cont, '(a,i0,a)') &
+        '(', len(trim(counter)) + 1, 'x,a)'
+    end if
+
+    ! -- calculate the length of the message
+    len_message = len_trim(amessage)
+
+    ! -- parse the message into multiple lines
+5   continue
+    jend = j + len_str2
+    if (jend >= len_message) go to 100
+    do i = jend, j + 1, -1
+    if (amessage(i:i) .eq. ' ') then
+      if (j == 0) then
+        if (include_counter) then
+          line = counter(1:len_str1)//amessage(j + 1:i)
+        else
+          line = amessage(j + 1:i)
+        end if
+        call write_message(text=line, iunit=iu, &
+                           fmt=fmt_first, &
+                           skipbefore=isb)
+      else
+        line = adjustl(amessage(j + 1:i))
+        call write_message(text=line, iunit=iu, &
+                           fmt=fmt_cont)
+      end if
+      j = i
+      go to 5
+    end if
+    end do
+    if (j == 0) then
+    if (include_counter) then
+      line = counter(1:len_str1)//amessage(j + 1:jend)
+    else
+      line = amessage(j + 1:jend)
+    end if
+    call write_message(text=line, iunit=iu, &
+                       fmt=fmt_first, &
+                       skipbefore=isb)
+    else
+    line = amessage(j + 1:jend)
+    call write_message(text=line, iunit=iu, &
+                       fmt=fmt_cont)
+    end if
+    j = jend
+    go to 5
+
+    ! -- last piece of amessage to write to a line
+100 continue
+    jend = len_message
+    if (j == 0) then
+      if (include_counter) then
+        line = counter(1:len_str1)//amessage(j + 1:jend)
+      else
+        line = amessage(j + 1:jend)
+      end if
+      call write_message(text=line, iunit=iu, &
+                         fmt=fmt_first, &
+                         skipbefore=isb, skipafter=isa)
+    else
+      line = amessage(j + 1:jend)
+      call write_message(text=line, iunit=iu, fmt=fmt_cont, &
+                         skipafter=isa)
     end if
-    !
-    ! -- return
-    return
-  end subroutine deallocate_message
+  end subroutine write_message_counter
+
+  !> @brief Write horizontally centered text, left-padding as needed.
+  subroutine write_message_centered(text, linelen, iunit)
+    ! -- dummy
+    character(len=*), intent(in) :: text !< message to write to iunit
+    integer(I4B), intent(in) :: linelen !< length of line to center text in
+    integer(I4B), intent(in), optional :: iunit !< output unit to write text
+    ! -- local
+    character(len=linelen) :: line
+    character(len=linelen) :: blank
+    integer(I4B) :: iu
+    integer(I4B) :: len_message
+    integer(I4B) :: jend
+    integer(I4B) :: ipad
+    integer(I4B) :: i
+    integer(I4B) :: j
+
+    if (present(iunit)) then
+      iu = iunit
+    else
+      iu = istdout
+    end if
+
+    ! -- initialize local variables
+    blank = ''
+    len_message = len_trim(adjustl(text))
+    j = 0
+
+    ! -- parse the amessage into multiple lines
+    outer: do while (.true.)
+      jend = j + linelen
+
+      ! last line
+      if (jend >= len_message) then
+        jend = len_message
+        line = text(j + 1:jend)
+        ipad = ((linelen - len_trim(line)) / 2)
+        call write_message(text=blank(1:ipad)//line, iunit=iunit)
+        exit outer
+      end if
+
+      do i = jend, j + 1, -1
+        if (text(i:i) .eq. ' ') then
+          line = text(j + 1:i)
+          ipad = ((linelen - len_trim(line)) / 2)
+          call write_message(text=blank(1:ipad)//line, iunit=iunit)
+          j = i
+          cycle outer
+        end if
+      end do
+
+      line = text(j + 1:jend)
+      ipad = ((linelen - len_trim(line)) / 2)
+      call write_message(text=blank(1:ipad)//line, iunit=iunit)
+      j = jend
+    end do outer
+  end subroutine write_message_centered
 
 end module MessageModule
diff --git a/src/Utilities/OutputControl/OutputControl.f90 b/src/Utilities/OutputControl/OutputControl.f90
index 8e3f72874b6..2cd2914c6c3 100644
--- a/src/Utilities/OutputControl/OutputControl.f90
+++ b/src/Utilities/OutputControl/OutputControl.f90
@@ -1,7 +1,7 @@
 !> @brief This module contains the OutputControlModule
 !!
 !! This module defines the OutputControlType.  This type
-!! is overriden by GWF and GWT to create an Output Control
+!! is overridden by GWF and GWT to create an Output Control
 !! package for the model.
 !!
 !<
diff --git a/src/Utilities/PackageBudget.f90 b/src/Utilities/PackageBudget.f90
index 93f1f5b2c6b..c6485cd904b 100644
--- a/src/Utilities/PackageBudget.f90
+++ b/src/Utilities/PackageBudget.f90
@@ -119,10 +119,20 @@ end subroutine set_auxname
   !!  GWF Package members stored in BndType.
   !!
   !<
-  subroutine set_pointers(this, flowvarname, mem_path_target)
+  subroutine set_pointers(this, flowvarname, mem_path_target, input_mempath)
+    use ConstantsModule, only: LENVARNAME
     class(PackageBudgetType) :: this !< PackageBudgetType object
     character(len=*), intent(in) :: flowvarname !< name of variable storing flow (SIMVALS, SIMTOMVR)
     character(len=*), intent(in) :: mem_path_target !< path where target variable is stored
+    character(len=*), intent(in) :: input_mempath
+    character(len=LENVARNAME) :: auxvarname
+    !
+    ! -- set memory manager aux varname
+    if (input_mempath /= '') then
+      auxvarname = 'AUXVAR_IDM'
+    else
+      auxvarname = 'AUXVAR'
+    end if
     !
     ! -- Reassign pointers to variables in the flow model
     call mem_reassignptr(this%nbound, 'NBOUND', this%memoryPath, &
@@ -132,7 +142,8 @@ subroutine set_pointers(this, flowvarname, mem_path_target)
     call mem_reassignptr(this%flow, 'FLOW', this%memoryPath, &
                          flowvarname, mem_path_target)
     call mem_reassignptr(this%auxvar, 'AUXVAR', this%memoryPath, &
-                         'AUXVAR', mem_path_target)
+                         auxvarname, mem_path_target)
+    !
     return
   end subroutine set_pointers
 
diff --git a/src/Utilities/Sim.f90 b/src/Utilities/Sim.f90
index 298f0c544a5..14d5a0103fa 100644
--- a/src/Utilities/Sim.f90
+++ b/src/Utilities/Sim.f90
@@ -10,6 +10,7 @@
 module SimModule
 
   use KindModule, only: DP, I4B
+  use ErrorUtilModule, only: pstop
   use DefinedMacros, only: get_os
   use ConstantsModule, only: MAXCHARLEN, LINELENGTH, &
                              DONE, &
@@ -19,8 +20,7 @@ module SimModule
   use SimVariablesModule, only: istdout, iout, isim_level, ireturnerr, &
                                 iforcestop, iunext, &
                                 warnmsg
-  use GenericUtilitiesModule, only: sim_message, stop_with_error
-  use MessageModule, only: MessageType
+  use MessageModule, only: MessagesType, write_message
 
   implicit none
 
@@ -41,89 +41,52 @@ module SimModule
   public :: store_error_filename
   public :: MaxErrors
 
-  type(MessageType) :: sim_errors
-  type(MessageType) :: sim_uniterrors
-  type(MessageType) :: sim_warnings
-  type(MessageType) :: sim_notes
+  type(MessagesType) :: sim_errors
+  type(MessagesType) :: sim_uniterrors
+  type(MessagesType) :: sim_warnings
+  type(MessagesType) :: sim_notes
 
 contains
 
   !> @brief Return number of errors
-    !!
-    !!  Function to return the number of errors messages that have been stored.
-    !!
-    !!  @return  ncount number of error messages stored
-    !!
+  !!
+  !! Function to return the number of errors messages that have been stored.
+  !!
+  !! @return  ncount number of error messages stored
+  !!
   !<
   function count_errors() result(ncount)
-    ! -- return variable
     integer(I4B) :: ncount
-    !
-    ! -- set ncount
-    ncount = sim_errors%count_message()
-    !
-    ! -- return
-    return
+    ncount = sim_errors%count()
   end function count_errors
 
   !> @brief Return number of warnings
-    !!
-    !!  Function to return the number of warning messages that have been stored.
-    !!
-    !!  @return  ncount number of warning messages stored
-    !!
+  !!
+  !! Function to return the number of warning messages that have been stored.
+  !!
+  !! @return  ncount number of warning messages stored
+  !!
   !<
   function count_warnings() result(ncount)
-    ! -- return variable
     integer(I4B) :: ncount
-    !
-    ! -- set ncount
-    ncount = sim_warnings%count_message()
-    !
-    ! -- return
-    return
+    ncount = sim_warnings%count()
   end function count_warnings
 
-  !> @brief Return number of notes
-    !!
-    !!  Function to return the number of notes that have been stored.
-    !!
-    !!  @return  ncount number of notes stored
-    !!
+  !> @brief Return the number of notes stored.
   !<
   function count_notes() result(ncount)
-    ! -- return variable
     integer(I4B) :: ncount
-    !
-    ! -- set ncount
-    ncount = sim_notes%count_message()
-    !
-    ! -- return
-    return
+    ncount = sim_notes%count()
   end function count_notes
 
-  !> @brief Set the maximum number of errors stored
-    !!
-    !!  Subroutine to set the maximum number of error messages that will be stored
-    !!  in a simulation.
-    !!
+  !> @brief Set the maximum number of errors to be stored.
   !<
   subroutine MaxErrors(imax)
-    ! -- dummy variables
     integer(I4B), intent(in) :: imax !< maximum number of error messages that will be stored
-    !
-    ! -- set the maximum number of error messages that will be saved
-    call sim_errors%set_max_message(imax)
-    !
-    ! -- return
-    return
+    call sim_errors%set_max(imax)
   end subroutine MaxErrors
 
-  !> @brief Store error message
-    !!
-    !!  Subroutine to store a error message for printing at the end of
-    !!  the simulation.
-    !!
+  !> @brief Store an error message.
   !<
   subroutine store_error(msg, terminate)
     ! -- dummy variable
@@ -140,24 +103,22 @@ subroutine store_error(msg, terminate)
     end if
     !
     ! -- store error
-    call sim_errors%store_message(msg)
+    call sim_errors%store(msg)
     !
     ! -- terminate the simulation
     if (lterminate) then
       call ustop()
     end if
-    !
-    ! -- return
-    return
+
   end subroutine store_error
 
   !> @brief Get the file name
-    !!
-    !!  Subroutine to get the file name from the unit number for a open file.
-    !!  If the INQUIRE function returns the full path (for example, the INTEL
-    !!  compiler) then the returned file name (fname) is limited to the filename
-    !!  without the path.
-    !!
+  !!
+  !!  Subroutine to get the file name from the unit number for a open file.
+  !!  If the INQUIRE function returns the full path (for example, the INTEL
+  !!  compiler) then the returned file name (fname) is limited to the filename
+  !!  without the path.
+  !!
   !<
   subroutine get_filename(iunit, fname)
     ! -- dummy variables
@@ -193,17 +154,15 @@ subroutine get_filename(iunit, fname)
       ilen = len_trim(fname)
       write (fname, '(a)') fname(ipos + 1:ilen)//' '
     end if
-    !
-    ! -- return
-    return
+
   end subroutine get_filename
 
   !> @brief Store the file unit number
-    !!
-    !!  Subroutine to convert the unit number for a open file to a file name
-    !!  and indicate that there is an error reading from the file. By default,
-    !!  the simulation is terminated when this subroutine is called.
-    !!
+  !!
+  !!  Subroutine to convert the unit number for a open file to a file name
+  !!  and indicate that there is an error reading from the file. By default,
+  !!  the simulation is terminated when this subroutine is called.
+  !!
   !<
   subroutine store_error_unit(iunit, terminate)
     ! -- dummy variables
@@ -225,22 +184,20 @@ subroutine store_error_unit(iunit, terminate)
     inquire (unit=iunit, name=fname)
     write (errmsg, '(3a)') &
       "Error occurred while reading file '", trim(adjustl(fname)), "'"
-    call sim_uniterrors%store_message(errmsg)
+    call sim_uniterrors%store(errmsg)
     !
     ! -- terminate the simulation
     if (lterminate) then
       call ustop()
     end if
-    !
-    ! -- return
-    return
+
   end subroutine store_error_unit
 
   !> @brief Store the erroring file name
-    !!
-    !!  Subroutine to store the file name issuing an error. By default,
-    !!  the simulation is terminated when this subroutine is called
-    !!
+  !!
+  !!  Subroutine to store the file name issuing an error. By default,
+  !!  the simulation is terminated when this subroutine is called
+  !!
   !<
   subroutine store_error_filename(filename, terminate)
     ! -- dummy variables
@@ -260,22 +217,20 @@ subroutine store_error_filename(filename, terminate)
     ! -- store error unit
     write (errmsg, '(3a)') &
       "ERROR OCCURRED WHILE READING FILE '", trim(adjustl(filename)), "'"
-    call sim_uniterrors%store_message(errmsg)
+    call sim_uniterrors%store(errmsg)
     !
     ! -- terminate the simulation
     if (lterminate) then
       call ustop()
     end if
-    !
-    ! -- return
-    return
+
   end subroutine store_error_filename
 
   !> @brief Store warning message
-    !!
-    !!  Subroutine to store a warning message for printing at the end of
-    !!  the simulation.
-    !!
+  !!
+  !!  Subroutine to store a warning message for printing at the end of
+  !!  the simulation.
+  !!
   !<
   subroutine store_warning(msg, substring)
     ! -- dummy variables
@@ -285,9 +240,9 @@ subroutine store_warning(msg, substring)
     !
     ! -- store warning
     if (present(substring)) then
-      call sim_warnings%store_message(msg, substring)
+      call sim_warnings%store(msg, substring)
     else
-      call sim_warnings%store_message(msg)
+      call sim_warnings%store(msg)
     end if
     !
     ! -- return
@@ -295,10 +250,10 @@ subroutine store_warning(msg, substring)
   end subroutine store_warning
 
   !> @brief Store deprecation warning message
-    !!
-    !!  Subroutine to store a warning message for deprecated variables
-    !!  and printing at the end of simulation.
-    !!
+  !!
+  !!  Subroutine to store a warning message for deprecated variables
+  !!  and printing at the end of simulation.
+  !!
   !<
   subroutine deprecation_warning(cblock, cvar, cver, endmsg, iunit)
     ! -- modules
@@ -330,16 +285,14 @@ subroutine deprecation_warning(cblock, cvar, cver, endmsg, iunit)
     end if
     !
     ! -- store warning
-    call sim_warnings%store_message(message)
-    !
-    ! -- return
-    return
+    call sim_warnings%store(message)
+
   end subroutine deprecation_warning
 
   !> @brief Store note
-    !!
-    !!  Subroutine to store a note for printing at the end of the simulation.
-    !!
+  !!
+  !! Subroutine to store a note for printing at the end of the simulation.
+  !!
   !<
   subroutine store_note(note)
     ! -- modules
@@ -348,17 +301,15 @@ subroutine store_note(note)
     character(len=*), intent(in) :: note !< note
     !
     ! -- store note
-    call sim_notes%store_message(note)
-    !
-    ! -- return
-    return
+    call sim_notes%store(note)
+
   end subroutine store_note
 
   !> @brief Stop the simulation.
-    !!
-    !!  Subroutine to stop the simulations with option to print message
-    !!  before stopping with the active error code.
-    !!
+  !!
+  !!  Subroutine to stop the simulations with option to print message
+  !!  before stopping with the active error code.
+  !!
   !<
   subroutine ustop(stopmess, ioutlocal)
     ! -- dummy variables
@@ -370,16 +321,16 @@ subroutine ustop(stopmess, ioutlocal)
     ! -- print the final message
     call print_final_message(stopmess, ioutlocal)
     !
-    ! -- return appropriate error codes when terminating the program
-    call stop_with_error(ireturnerr)
+    ! -- terminate with the appropriate error code
+    call pstop(ireturnerr)
 
   end subroutine ustop
 
   !> @brief Print the final messages
-    !!
-    !!  Subroutine to print the notes, warnings, errors and the final message (if passed).
-    !!  The subroutine also closes all open files.
-    !!
+  !!
+  !!  Subroutine to print the notes, warnings, errors and the final message (if passed).
+  !!  The subroutine also closes all open files.
+  !!
   !<
   subroutine print_final_message(stopmess, ioutlocal)
     ! -- dummy variables
@@ -392,19 +343,21 @@ subroutine print_final_message(stopmess, ioutlocal)
     character(len=*), parameter :: msg = 'Stopping due to error(s)'
     !
     ! -- print the accumulated messages
-    call sim_notes%print_message('NOTES:', 'note(s)', &
-                                 iunit=iout, level=VALL)
-    call sim_warnings%print_message('WARNING REPORT:', 'warning(s)', &
-                                    iunit=iout, level=VALL)
-    call sim_errors%print_message('ERROR REPORT:', 'error(s)', iunit=iout)
-    call sim_uniterrors%print_message('UNIT ERROR REPORT:', &
-                                      'file unit error(s)', iunit=iout)
+    if (isim_level >= VALL) then
+      call sim_notes%write_all('NOTES:', 'note(s)', &
+                               iunit=iout)
+      call sim_warnings%write_all('WARNING REPORT:', 'warning(s)', &
+                                  iunit=iout)
+    end if
+    call sim_errors%write_all('ERROR REPORT:', 'error(s)', iunit=iout)
+    call sim_uniterrors%write_all('UNIT ERROR REPORT:', &
+                                  'file unit error(s)', iunit=iout)
     !
     ! -- write a stop message, if one is passed
     if (present(stopmess)) then
       if (stopmess .ne. ' ') then
-        call sim_message(stopmess, fmt=fmt, iunit=iout)
-        call sim_message(stopmess, fmt=fmt)
+        call write_message(stopmess, fmt=fmt, iunit=iout)
+        call write_message(stopmess, fmt=fmt)
         if (present(ioutlocal)) then
           if (ioutlocal > 0 .and. ioutlocal /= iout) then
             write (ioutlocal, fmt) trim(stopmess)
@@ -418,7 +371,7 @@ subroutine print_final_message(stopmess, ioutlocal)
     flush (istdout)
     !
     ! -- determine if an error condition has occurred
-    if (sim_errors%count_message() > 0) then
+    if (sim_errors%count() > 0) then
       ireturnerr = 2
       if (present(ioutlocal)) then
         if (ioutlocal > 0 .and. ioutlocal /= iout) write (ioutlocal, fmt) msg
@@ -427,34 +380,26 @@ subroutine print_final_message(stopmess, ioutlocal)
     !
     ! -- close all open files
     call sim_closefiles()
-    !
-    ! -- return
-    return
+
   end subroutine print_final_message
 
   !> @brief Reset the simulation convergence flag
-    !!
-    !!  Subroutine to reset the simulation convergence flag.
-    !!
+  !!
+  !!  Subroutine to reset the simulation convergence flag.
+  !!
   !<
   subroutine converge_reset()
-    ! -- modules
     use SimVariablesModule, only: isimcnvg
-    !
-    ! -- reset simulation convergence flag
     isimcnvg = 1
-    !
-    ! -- return
-    return
   end subroutine converge_reset
 
   !> @brief Simulation convergence check
-    !!
-    !!  Subroutine to check simulation convergence. If the continue option is
-    !!  set the simulation convergence flag is set to True if the simulation
-    !!  did not actually converge for a time step and the non-convergence counter
-    !!  is incremented.
-    !!
+  !!
+  !!  Subroutine to check simulation convergence. If the continue option is
+  !!  set the simulation convergence flag is set to True if the simulation
+  !!  did not actually converge for a time step and the non-convergence counter
+  !!  is incremented.
+  !!
   !<
   subroutine converge_check(hasConverged)
     ! -- modules
@@ -484,19 +429,17 @@ subroutine converge_check(hasConverged)
     !
     ! -- save simulation failure message
     if (isimcnvg == 0) then
-      call sim_message('', fmt=fmtfail, iunit=iout)
+      call write_message('', fmt=fmtfail, iunit=iout)
       hasConverged = .false.
     end if
-    !
-    ! -- return
-    return
+
   end subroutine converge_check
 
   !> @brief Print the header and initializes messaging
-    !!
-    !! Subroutine that prints the initial message and initializes the notes,
-    !! warning messages, unit errors, and error messages.
-    !!
+  !!
+  !! Subroutine that prints the initial message and initializes the notes,
+  !! warning messages, unit errors, and error messages.
+  !!
   !<
   subroutine initial_message()
     ! -- modules
@@ -504,27 +447,27 @@ subroutine initial_message()
     use SimVariablesModule, only: simulation_mode
     !
     ! -- initialize message lists
-    call sim_errors%init_message()
-    call sim_uniterrors%init_message()
-    call sim_warnings%init_message()
-    call sim_notes%init_message()
+    call sim_errors%init()
+    call sim_uniterrors%init()
+    call sim_warnings%init()
+    call sim_notes%init()
     !
     ! -- Write banner to screen (unit stdout)
     call write_listfile_header(istdout, write_kind_info=.false., &
                                write_sys_command=.false.)
     !
     if (simulation_mode == 'PARALLEL') then
-      call sim_message('(MODFLOW runs in '//trim(simulation_mode)//' mode)', &
-                       skipafter=1)
+      call write_message('(MODFLOW runs in '//trim(simulation_mode)//' mode)', &
+                         skipafter=1)
     end if
     !
   end subroutine initial_message
 
   !> @brief Create final message
-    !!
-    !! Subroutine that creates the appropriate final message and
-    !! terminates the program with an error message, if necessary.
-    !!
+  !!
+  !! Subroutine that creates the appropriate final message and
+  !! terminates the program with an error message, if necessary.
+  !!
   !<
   subroutine final_message()
     ! -- modules
@@ -538,9 +481,9 @@ subroutine final_message()
     if (numnoconverge > 0) then
       write (warnmsg, fmtnocnvg) numnoconverge
       if (isimcontinue == 0) then
-        call sim_errors%store_message(warnmsg)
+        call sim_errors%store(warnmsg)
       else
-        call sim_warnings%store_message(warnmsg)
+        call sim_warnings%store(warnmsg)
       end if
     end if
     !
@@ -562,26 +505,24 @@ subroutine final_message()
     end if
     !
     ! -- destroy messages
-    call sim_errors%deallocate_message()
-    call sim_uniterrors%deallocate_message()
-    call sim_warnings%deallocate_message()
-    call sim_notes%deallocate_message()
+    call sim_errors%deallocate()
+    call sim_uniterrors%deallocate()
+    call sim_warnings%deallocate()
+    call sim_notes%deallocate()
     !
     ! -- return or halt
     if (iforcestop == 1) then
-      call stop_with_error(ireturnerr)
+      call pstop(ireturnerr)
     end if
 
   end subroutine final_message
 
   !> @brief Close all open files
-    !!
-    !! Subroutine that closes all open files at the end of the simulation.
-    !!
+  !!
+  !! Subroutine that closes all open files at the end of the simulation.
+  !!
   !<
   subroutine sim_closefiles()
-    ! -- modules
-    ! -- dummy
     ! -- local variables
     integer(I4B) :: i
     logical :: opened
@@ -607,9 +548,7 @@ subroutine sim_closefiles()
       ! -- close file unit i
       close (i)
     end do
-    !
-    ! -- return
-    return
+
   end subroutine sim_closefiles
 
 end module SimModule
diff --git a/src/Utilities/SimStages.f90 b/src/Utilities/SimStages.f90
index 8094b71b5dc..9168f05b9a8 100644
--- a/src/Utilities/SimStages.f90
+++ b/src/Utilities/SimStages.f90
@@ -16,9 +16,11 @@ module SimStagesModule
   integer(I4B), public, parameter :: STG_BFR_EXG_AC = 7 !< before exchange add connections (per solution)
   integer(I4B), public, parameter :: STG_BFR_CON_AR = 8 !< before connection allocate read
   integer(I4B), public, parameter :: STG_AFT_CON_AR = 9 !< afterr connection allocate read
-  integer(I4B), public, parameter :: STG_BFR_EXG_AD = 10 !< before exchange advance (per solution)
-  integer(I4B), public, parameter :: STG_BFR_EXG_CF = 11 !< before exchange calculate (per solution)
-  integer(I4B), public, parameter :: STG_BFR_EXG_FC = 12 !< before exchange formulate (per solution)
+  integer(I4B), public, parameter :: STG_BFR_EXG_RP = 10 !< before exchange read prepare
+  integer(I4B), public, parameter :: STG_AFT_CON_RP = 11 !< after connection read prepare
+  integer(I4B), public, parameter :: STG_BFR_EXG_AD = 12 !< before exchange advance (per solution)
+  integer(I4B), public, parameter :: STG_BFR_EXG_CF = 13 !< before exchange calculate (per solution)
+  integer(I4B), public, parameter :: STG_BFR_EXG_FC = 14 !< before exchange formulate (per solution)
 
 contains
 
@@ -38,6 +40,8 @@ function STG_TO_STR(stage) result(stg_str)
     else if (stage == STG_BFR_EXG_AC) then; stg_str = "STG_BFR_EXG_AC"
     else if (stage == STG_BFR_CON_AR) then; stg_str = "STG_BFR_CON_AR"
     else if (stage == STG_AFT_CON_AR) then; stg_str = "STG_AFT_CON_AR"
+    else if (stage == STG_BFR_EXG_RP) then; stg_str = "STG_BFR_EXG_RP"
+    else if (stage == STG_AFT_CON_RP) then; stg_str = "STG_AFT_CON_RP"
     else if (stage == STG_BFR_EXG_AD) then; stg_str = "STG_BFR_EXG_AD"
     else if (stage == STG_BFR_EXG_CF) then; stg_str = "STG_BFR_EXG_CF"
     else if (stage == STG_BFR_EXG_FC) then; stg_str = "STG_BFR_EXG_FC"
diff --git a/src/Utilities/SmoothingFunctions.f90 b/src/Utilities/SmoothingFunctions.f90
index c821e14c67d..657457b79de 100644
--- a/src/Utilities/SmoothingFunctions.f90
+++ b/src/Utilities/SmoothingFunctions.f90
@@ -6,14 +6,12 @@ module SmoothingModule
 
 contains
 
+  !> @ brief SCurve
+  !!
+  !! Computes the S curve for smooth derivatives between x=0 and x=1
+  !! from mfusg smooth subroutine in gwf2wel7u1.f
+  !<
   subroutine sSCurve(x, range, dydx, y)
-! ******************************************************************************
-! COMPUTES THE S CURVE FOR SMOOTH DERIVATIVES BETWEEN X=0 AND X=1
-! FROM mfusg smooth SUBROUTINE in gwf2wel7u1.f
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     real(DP), intent(in) :: x
     real(DP), intent(in) :: range
     real(DP), intent(inout) :: dydx
@@ -21,9 +19,8 @@ subroutine sSCurve(x, range, dydx, y)
     !--local variables
     real(DP) :: s
     real(DP) :: xs
-! ------------------------------------------------------------------------------
-!   code
-!
+    ! -- code
+    !
     s = range
     if (s < DPREC) s = DPREC
     xs = x / s
@@ -41,14 +38,12 @@ subroutine sSCurve(x, range, dydx, y)
     return
   end subroutine sSCurve
 
+  !> @ brief sCubicLinear
+  !!
+  !! Computes the s curve where dy/dx = 0 at x=0; and dy/dx = 1 at x=1.
+  !! Smooths from zero to a slope of 1.
+  !<
   subroutine sCubicLinear(x, range, dydx, y)
-! ******************************************************************************
-! COMPUTES THE S CURVE WHERE DY/DX = 0 at X=0; AND DY/DX = 1 AT X=1.
-! Smooths from zero to a slope of 1.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     real(DP), intent(in) :: x
     real(DP), intent(in) :: range
     real(DP), intent(inout) :: dydx
@@ -56,9 +51,8 @@ subroutine sCubicLinear(x, range, dydx, y)
     !--local variables
     real(DP) :: s
     real(DP) :: xs
-! ------------------------------------------------------------------------------
-!   code
-!
+    ! -- code
+    !
     s = range
     if (s < DPREC) s = DPREC
     xs = x / s
@@ -76,13 +70,11 @@ subroutine sCubicLinear(x, range, dydx, y)
     return
   end subroutine sCubicLinear
 
+  !> @ brief sCubic
+  !!
+  !! Nonlinear smoothing function returns value between 0-1; cubic function
+  !<
   subroutine sCubic(x, range, dydx, y)
-! ******************************************************************************
-! Nonlinear smoothing function returns value between 0-1; cubic function
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     real(DP), intent(inout) :: x
     real(DP), intent(inout) :: range
     real(DP), intent(inout) :: dydx
@@ -90,9 +82,8 @@ subroutine sCubic(x, range, dydx, y)
     !--local variables
     real(DP) :: s, aa, bb
     real(DP) :: cof1, cof2, cof3
-! ------------------------------------------------------------------------------
-!   code
-!
+    ! -- code
+    !
     dydx = DZERO
     y = DZERO
     if (range < DPREC) range = DPREC
@@ -115,22 +106,19 @@ subroutine sCubic(x, range, dydx, y)
     return
   end subroutine sCubic
 
+  !> @ brief sLinear
+  !!
+  !! Linear smoothing function returns value between 0-1
+  !<
   subroutine sLinear(x, range, dydx, y)
-! ******************************************************************************
-! Linear smoothing function returns value between 0-1
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     real(DP), intent(inout) :: x
     real(DP), intent(inout) :: range
     real(DP), intent(inout) :: dydx
     real(DP), intent(inout) :: y
     !--local variables
     real(DP) :: s
-! ------------------------------------------------------------------------------
-!   code
-!
+    ! -- code
+    !
     dydx = DZERO
     y = DZERO
     if (range < DPREC) range = DPREC
@@ -145,22 +133,19 @@ subroutine sLinear(x, range, dydx, y)
     return
   end subroutine sLinear
 
+  !> @ brief sQuadratic
+  !!
+  !! Nonlinear quadratic smoothing function returns value between 0-1
+  !<
   subroutine sQuadratic(x, range, dydx, y)
-! ******************************************************************************
-! Nonlinear smoothing function returns value between 0-1; quadratic function
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     real(DP), intent(inout) :: x
     real(DP), intent(inout) :: range
     real(DP), intent(inout) :: dydx
     real(DP), intent(inout) :: y
     !--local variables
     real(DP) :: s
-! ------------------------------------------------------------------------------
-!   code
-!
+    ! -- code
+    !
     dydx = DZERO
     y = DZERO
     if (range < DPREC) range = DPREC
@@ -175,13 +160,11 @@ subroutine sQuadratic(x, range, dydx, y)
     return
   end subroutine sQuadratic
 
+  !> @ brief sChSmooth
+  !!
+  !! Function to smooth channel variables during channel drying
+  !<
   subroutine sChSmooth(d, smooth, dwdh)
-! ******************************************************************************
-! Function to smooth channel variables during channel drying
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     real(DP), intent(in) :: d
     real(DP), intent(inout) :: smooth
     real(DP), intent(inout) :: dwdh
@@ -194,9 +177,8 @@ subroutine sChSmooth(d, smooth, dwdh)
     real(DP) :: b
     real(DP) :: x
     real(DP) :: y
-! ------------------------------------------------------------------------------
-!   code
-!
+    ! -- code
+    !
     smooth = DZERO
     s = DEM5
     x = d
@@ -222,14 +204,11 @@ subroutine sChSmooth(d, smooth, dwdh)
     return
   end subroutine sChSmooth
 
+  !> @ brief sLinearSaturation
+  !!
+  !! Linear saturation function returns value between 0-1
+  !<
   function sLinearSaturation(top, bot, x) result(y)
-! ******************************************************************************
-! Linear smoothing function returns value between 0-1;
-! Linear saturation function
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: y
     ! -- dummy variables
@@ -238,9 +217,8 @@ function sLinearSaturation(top, bot, x) result(y)
     real(DP), intent(in) :: x
     ! -- local
     real(DP) :: b
-! ------------------------------------------------------------------------------
-!   code
-!
+    ! -- code
+    !
     b = top - bot
     if (x < bot) then
       y = DZERO
@@ -252,14 +230,11 @@ function sLinearSaturation(top, bot, x) result(y)
     return
   end function sLinearSaturation
 
+  !> @ brief sCubicSaturation
+  !!
+  !! Nonlinear cubic saturation function returns value between 0-1
+  !<
   function sCubicSaturation(top, bot, x, eps) result(y)
-! ******************************************************************************
-! Nonlinear smoothing function returns value between 0-1;
-! Quadratic saturation function
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: y
     ! -- dummy variables
@@ -274,9 +249,8 @@ function sCubicSaturation(top, bot, x, eps) result(y)
     real(DP) :: s
     real(DP) :: cof1
     real(DP) :: cof2
-! ------------------------------------------------------------------------------
-!   code
-!
+    ! -- code
+    !
     if (present(eps)) then
       teps = eps
     else
@@ -302,14 +276,11 @@ function sCubicSaturation(top, bot, x, eps) result(y)
     return
   end function sCubicSaturation
 
+  !> @ brief sQuadraticSaturation
+  !!
+  !! Nonlinear quadratic saturation function returns value between 0-1
+  !<
   function sQuadraticSaturation(top, bot, x, eps, bmin) result(y)
-! ******************************************************************************
-! Nonlinear smoothing function returns value between 0-1;
-! Quadratic saturation function
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: y
     ! -- dummy variables
@@ -325,9 +296,8 @@ function sQuadraticSaturation(top, bot, x, eps, bmin) result(y)
     real(DP) :: br
     real(DP) :: bri
     real(DP) :: av
-! ------------------------------------------------------------------------------
-!   code
-!
+    ! -- code
+    !
     if (present(eps)) then
       teps = eps
     else
@@ -372,14 +342,11 @@ function sQuadraticSaturation(top, bot, x, eps, bmin) result(y)
     return
   end function sQuadraticSaturation
 
+  !> @ brief sQuadraticSaturation
+  !!
+  !! van Genuchten saturation function returns value between 0-1
+  !<
   function svanGenuchtenSaturation(top, bot, x, alpha, beta, sr) result(y)
-! ******************************************************************************
-! Nonlinear smoothing function returns value between 0-1;
-! van Genuchten saturation function
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: y
     ! -- dummy variables
@@ -394,9 +361,8 @@ function svanGenuchtenSaturation(top, bot, x, alpha, beta, sr) result(y)
     real(DP) :: pc
     real(DP) :: gamma
     real(DP) :: seff
-! ------------------------------------------------------------------------------
-!   code
-!
+    ! -- code
+    !
     b = top - bot
     pc = (DHALF * b) - x
     if (pc <= DZERO) then
@@ -411,14 +377,11 @@ function svanGenuchtenSaturation(top, bot, x, alpha, beta, sr) result(y)
     return
   end function svanGenuchtenSaturation
 
+  !> @ brief Derivative of the quadratic saturation function
+  !!
+  !! Derivative of nonlinear smoothing function returns value between 0-1;
+  !<
   function sQuadraticSaturationDerivative(top, bot, x, eps, bmin) result(y)
-! ******************************************************************************
-! Derivative of nonlinear smoothing function returns value between 0-1;
-! Derivative of the quadratic saturation function
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: y
     ! -- dummy variables
@@ -434,9 +397,8 @@ function sQuadraticSaturationDerivative(top, bot, x, eps, bmin) result(y)
     real(DP) :: br
     real(DP) :: bri
     real(DP) :: av
-! ------------------------------------------------------------------------------
-!   code
-!
+    ! -- code
+    !
     if (present(eps)) then
       teps = eps
     else
@@ -474,14 +436,11 @@ function sQuadraticSaturationDerivative(top, bot, x, eps, bmin) result(y)
     return
   end function sQuadraticSaturationDerivative
 
+  !> @ brief sQSaturation
+  !!
+  !! Nonlinear smoothing function returns value between 0-1
+  !<
   function sQSaturation(top, bot, x, c1, c2) result(y)
-! ******************************************************************************
-! Nonlinear smoothing function returns value between 0-1;
-! Cubic saturation function
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: y
     ! -- dummy variables
@@ -496,9 +455,7 @@ function sQSaturation(top, bot, x, c1, c2) result(y)
     real(DP) :: s
     real(DP) :: cof1
     real(DP) :: cof2
-! ------------------------------------------------------------------------------
-!   code
-!
+    ! -- code
     !
     ! -- process optional variables
     if (present(c1)) then
@@ -536,14 +493,11 @@ function sQSaturation(top, bot, x, c1, c2) result(y)
     return
   end function sQSaturation
 
+  !> @ brief sQSaturationDerivative
+  !!
+  !! Nonlinear smoothing function returns value between 0-1
+  !<
   function sQSaturationDerivative(top, bot, x, c1, c2) result(y)
-! ******************************************************************************
-! Nonlinear smoothing function returns value between 0-1;
-! Cubic saturation function
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: y
     ! -- dummy variables
@@ -558,9 +512,8 @@ function sQSaturationDerivative(top, bot, x, c1, c2) result(y)
     real(DP) :: s
     real(DP) :: cof1
     real(DP) :: cof2
-! ------------------------------------------------------------------------------
-!   code
-!
+    ! -- code
+    !
     !
     ! -- process optional variables
     if (present(c1)) then
@@ -599,15 +552,13 @@ function sQSaturationDerivative(top, bot, x, c1, c2) result(y)
     return
   end function sQSaturationDerivative
 
+  !> @ brief sSlope
+  !!
+  !! Nonlinear smoothing function returns a smoothed value of y that has the value
+  !! yi at xi and yi + (sm * dx) for x-values less than xi and yi + (sp * dx) for
+  !! x-values greater than xi, where dx = x - xi.
+  !<
   function sSlope(x, xi, yi, sm, sp, ta) result(y)
-! ******************************************************************************
-! Nonlinear smoothing function returns a smoothed value of y that has the value
-! yi at xi and yi + (sm * dx) for x-values less than xi and yi + (sp * dx) for
-! x-values greater than xi, where dx = x - xi.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: y
     ! -- dummy variables
@@ -625,7 +576,6 @@ function sSlope(x, xi, yi, sm, sp, ta) result(y)
     real(DP) :: xp
     real(DP) :: ym
     real(DP) :: yp
-! ------------------------------------------------------------------------------
     !
     ! -- set smoothing variable a
     if (present(ta)) then
@@ -651,15 +601,13 @@ function sSlope(x, xi, yi, sm, sp, ta) result(y)
     return
   end function sSlope
 
+  !> @ brief sSlopeDerivative
+  !!
+  !! Derivative of nonlinear smoothing function that has the value yi at xi and
+  !! yi + (sm * dx) for x-values less than xi and yi + (sp * dx) for x-values
+  !! greater than xi, where dx = x - xi.
+  !<
   function sSlopeDerivative(x, xi, sm, sp, ta) result(y)
-! ******************************************************************************
-! Derivative of nonlinear smoothing function that has the value yi at xi and
-! yi + (sm * dx) for x-values less than xi and yi + (sp * dx) for x-values
-! greater than xi, where dx = x - xi.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: y
     ! -- dummy variables
@@ -674,7 +622,6 @@ function sSlopeDerivative(x, xi, sm, sp, ta) result(y)
     real(DP) :: dx
     real(DP) :: mu
     real(DP) :: rho
-! ------------------------------------------------------------------------------
     !
     ! -- set smoothing variable a
     if (present(ta)) then
@@ -698,16 +645,14 @@ function sSlopeDerivative(x, xi, sm, sp, ta) result(y)
     return
   end function sSlopeDerivative
 
+  !> @ brief sQuadratic0sp
+  !!
+  !! Nonlinear smoothing function returns a smoothed value of y that uses a
+  !! quadratic to smooth x over range of xi - epsilon to xi + epsilon.
+  !! Simplification of sQuadraticSlope with sm = 0, sp = 1, and yi = 0.
+  !! From Panday et al. (2013) - eq. 35 - https://dx.doi.org/10.5066/F7R20ZFJ
+  !<
   function sQuadratic0sp(x, xi, tomega) result(y)
-! ******************************************************************************
-! Nonlinear smoothing function returns a smoothed value of y that uses a
-! quadratic to smooth x over range of xi - epsilon to xi + epsilon.
-! Simplification of sQuadraticSlope with sm = 0, sp = 1, and yi = 0.
-! From Panday et al. (2013) - eq. 35 - https://dx.doi.org/10.5066/F7R20ZFJ
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: y
     ! -- dummy variables
@@ -718,7 +663,6 @@ function sQuadratic0sp(x, xi, tomega) result(y)
     real(DP) :: omega
     real(DP) :: epsilon
     real(DP) :: dx
-! ------------------------------------------------------------------------------
     !
     ! -- set smoothing interval
     if (present(tomega)) then
@@ -746,16 +690,14 @@ function sQuadratic0sp(x, xi, tomega) result(y)
     return
   end function sQuadratic0sp
 
+  !> @ brief sQuadratic0spDerivative
+  !!
+  !! Derivative of nonlinear smoothing function returns a smoothed value of y
+  !! that uses a quadratic to smooth x over range of xi - epsilon to xi + epsilon.
+  !! Simplification of sQuadraticSlope with sm = 0, sp = 1, and yi = 0.
+  !! From Panday et al. (2013) - eq. 35 - https://dx.doi.org/10.5066/F7R20ZFJ
+  !<
   function sQuadratic0spDerivative(x, xi, tomega) result(y)
-! ******************************************************************************
-! Derivative of nonlinear smoothing function returns a smoothed value of y
-! that uses a quadratic to smooth x over range of xi - epsilon to xi + epsilon.
-! Simplification of sQuadraticSlope with sm = 0, sp = 1, and yi = 0.
-! From Panday et al. (2013) - eq. 35 - https://dx.doi.org/10.5066/F7R20ZFJ
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: y
     ! -- dummy variables
@@ -766,7 +708,6 @@ function sQuadratic0spDerivative(x, xi, tomega) result(y)
     real(DP) :: omega
     real(DP) :: epsilon
     real(DP) :: dx
-! ------------------------------------------------------------------------------
     !
     ! -- set smoothing interval
     if (present(tomega)) then
@@ -794,15 +735,13 @@ function sQuadratic0spDerivative(x, xi, tomega) result(y)
     return
   end function sQuadratic0spDerivative
 
+  !> @ brief sQuadraticSlope
+  !!
+  !! Quadratic smoothing function returns a smoothed value of y that has the value
+  !! yi at xi and yi + (sm * dx) for x-values less than xi and yi + (sp * dx) for
+  !! x-values greater than xi, where dx = x - xi.
+  !<
   function sQuadraticSlope(x, xi, yi, sm, sp, tomega) result(y)
-! ******************************************************************************
-! Quadratic smoothing function returns a smoothed value of y that has the value
-! yi at xi and yi + (sm * dx) for x-values less than xi and yi + (sp * dx) for
-! x-values greater than xi, where dx = x - xi.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: y
     ! -- dummy variables
@@ -817,7 +756,6 @@ function sQuadraticSlope(x, xi, yi, sm, sp, tomega) result(y)
     real(DP) :: epsilon
     real(DP) :: dx
     real(DP) :: c
-! ------------------------------------------------------------------------------
     !
     ! -- set smoothing interval
     if (present(tomega)) then
@@ -849,15 +787,13 @@ function sQuadraticSlope(x, xi, yi, sm, sp, tomega) result(y)
     return
   end function sQuadraticSlope
 
+  !> @ brief sQuadraticSlopeDerivative
+  !!
+  !! Derivative of quadratic smoothing function returns a smoothed value of y
+  !! that has the value yi at xi and yi + (sm * dx) for x-values less than xi and
+  !! yi + (sp * dx) for x-values greater than xi, where dx = x - xi.
+  !<
   function sQuadraticSlopeDerivative(x, xi, sm, sp, tomega) result(y)
-! ******************************************************************************
-! Derivative of quadratic smoothing function returns a smoothed value of y
-! that has the value yi at xi and yi + (sm * dx) for x-values less than xi and
-! yi + (sp * dx) for x-values greater than xi, where dx = x - xi.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: y
     ! -- dummy variables
@@ -871,7 +807,6 @@ function sQuadraticSlopeDerivative(x, xi, sm, sp, tomega) result(y)
     real(DP) :: epsilon
     real(DP) :: dx
     real(DP) :: c
-! ------------------------------------------------------------------------------
     !
     ! -- set smoothing interval
     if (present(tomega)) then
diff --git a/src/Utilities/TimeSeries/TimeArray.f90 b/src/Utilities/TimeSeries/TimeArray.f90
index 49b7ee99e4c..0463d278d47 100644
--- a/src/Utilities/TimeSeries/TimeArray.f90
+++ b/src/Utilities/TimeSeries/TimeArray.f90
@@ -1,6 +1,5 @@
 module TimeArrayModule
 
-  use BaseDisModule, only: DisBaseType
   use KindModule, only: DP, I4B
   use ListModule, only: ListType
   use SimVariablesModule, only: errmsg
@@ -16,7 +15,9 @@ module TimeArrayModule
     ! -- Public members
     real(DP), public :: taTime
     real(DP), dimension(:), pointer, contiguous, public :: taArray => null()
+
   contains
+
     ! -- Public procedures
     ! -- When gfortran adds support for finalization, the
     !    following declaration could be: final :: finalize
@@ -25,46 +26,59 @@ module TimeArrayModule
 
 contains
 
-  subroutine ConstructTimeArray(newTa, dis)
-! ******************************************************************************
-! ConstructTimeArray -- construct time array
-!   Allocate and assign members of a new TimeArrayType object.
-!   Allocate space for the array so that this subroutine can be
-!   called repeatedly with the same array (but with different contents).
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Construct time array
+  !!
+  !! Allocate and assign members of a new TimeArrayType object. Allocate space
+  !! for the array so that this subroutine can be called repeatedly with the
+  !! same array (but with different contents).
+  !<
+  subroutine ConstructTimeArray(newTa, modelname)
+    ! -- modules
+    use ConstantsModule, only: LENMEMPATH
+    use MemoryManagerModule, only: mem_setptr
+    use MemoryHelperModule, only: create_mem_path
     ! -- dummy
     type(TimeArrayType), pointer, intent(out) :: newTa
-    class(DisBaseType), pointer, intent(in) :: dis
+    character(len=*), intent(in) :: modelname
     ! -- local
+    integer(I4B), dimension(:), contiguous, &
+      pointer :: mshape
+    character(len=LENMEMPATH) :: mempath
     integer(I4B) :: isize
-! ------------------------------------------------------------------------------
+    !
+    ! -- initialize
+    nullify (mshape)
+    !
+    ! -- create mempath
+    mempath = create_mem_path(component=modelname, subcomponent='DIS')
+    !
+    ! -- set mshape pointer
+    call mem_setptr(mshape, 'MSHAPE', mempath)
     !
     ! Get dimensions for supported discretization type
-    if (dis%supports_layers()) then
-      isize = dis%get_ncpl()
+    if (size(mshape) == 2) then
+      isize = mshape(2)
+    else if (size(mshape) == 3) then
+      isize = mshape(2) * mshape(3)
     else
       errmsg = 'Time array series is not supported for discretization type'
       call store_error(errmsg, terminate=.TRUE.)
     end if
+    !
     allocate (newTa)
     allocate (newTa%taArray(isize))
+    !
+    ! -- Return
     return
   end subroutine ConstructTimeArray
 
+  !> @brief Cast an unlimited polymorphic object as TimeArrayType
+  !<
   function CastAsTimeArrayType(obj) result(res)
-! ******************************************************************************
-! ConstructTimeArray -- Cast an unlimited polymorphic object as TimeArrayType
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(*), pointer, intent(inout) :: obj
+    ! -- return
     type(TimeArrayType), pointer :: res
-! ------------------------------------------------------------------------------
     !
     res => null()
     if (.not. associated(obj)) return
@@ -73,64 +87,55 @@ function CastAsTimeArrayType(obj) result(res)
     type is (TimeArrayType)
       res => obj
     end select
+    !
+    ! -- Return
     return
   end function CastAsTimeArrayType
 
+  !> @brief Add a time array to a to list
+  !<
   subroutine AddTimeArrayToList(list, timearray)
-! ******************************************************************************
-! AddTimeArrayToList -- add ta to list
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(ListType), intent(inout) :: list
     type(TimeArrayType), pointer, intent(inout) :: timearray
     ! -- local
     class(*), pointer :: obj
-! ------------------------------------------------------------------------------
     !
     obj => timearray
     call list%Add(obj)
     !
+    ! -- Return
     return
   end subroutine AddTimeArrayToList
 
+  !> @brief Retrieve a time array from a list
+  !<
   function GetTimeArrayFromList(list, indx) result(res)
-! ******************************************************************************
-! GetTimeArrayFromList -- get ta from list
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(ListType), intent(inout) :: list
     integer(I4B), intent(in) :: indx
+    ! -- return
     type(TimeArrayType), pointer :: res
     ! -- local
     class(*), pointer :: obj
-! ------------------------------------------------------------------------------
     !
     obj => list%GetItem(indx)
     res => CastAsTimeArrayType(obj)
     !
+    ! -- Return
     return
   end function GetTimeArrayFromList
 
+  !> @brief Deallocate memory
+  !<
   subroutine ta_da(this)
-! ******************************************************************************
-! ta_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeArrayType) :: this
-! ------------------------------------------------------------------------------
     !
     deallocate (this%taArray)
     this%taArray => null()
     !
+    ! -- Return
     return
   end subroutine ta_da
 
diff --git a/src/Utilities/TimeSeries/TimeArraySeries.f90 b/src/Utilities/TimeSeries/TimeArraySeries.f90
index 34119ffa65a..7c8c4607bbc 100644
--- a/src/Utilities/TimeSeries/TimeArraySeries.f90
+++ b/src/Utilities/TimeSeries/TimeArraySeries.f90
@@ -3,8 +3,8 @@ module TimeArraySeriesModule
   use ArrayReadersModule, only: ReadArray
   use BlockParserModule, only: BlockParserType
   use ConstantsModule, only: LINELENGTH, UNDEFINED, STEPWISE, LINEAR, &
-                             LENTIMESERIESNAME, DZERO, DONE
-  use GenericUtilitiesModule, only: is_same
+                             LENTIMESERIESNAME, LENMODELNAME, DZERO, DONE
+  use MathUtilModule, only: is_close
   use InputOutputModule, only: GetUnit, openfile
   use KindModule, only: DP, I4B
   use ListModule, only: ListType, ListNodeType
@@ -13,7 +13,6 @@ module TimeArraySeriesModule
   use TimeArrayModule, only: TimeArrayType, ConstructTimeArray, &
                              AddTimeArrayToList, CastAsTimeArrayType, &
                              GetTimeArrayFromList
-  use BaseDisModule, only: DisBaseType
   use, intrinsic :: iso_fortran_env, only: IOSTAT_END
 
   implicit none
@@ -32,9 +31,11 @@ module TimeArraySeriesModule
     character(len=LINELENGTH), private :: dataFile = ''
     logical, private :: autoDeallocate = .true.
     type(ListType), pointer, private :: list => null()
-    class(DisBaseType), pointer, private :: dis => null()
+    character(len=LENMODELNAME) :: modelname
     type(BlockParserType), private :: parser
+
   contains
+
     ! -- Public procedures
     procedure, public :: tas_init
     procedure, public :: GetAverageValues
@@ -53,20 +54,15 @@ module TimeArraySeriesModule
 
   ! -- Constructor for TimeArraySeriesType
 
+  !> @brief Allocate a new TimeArraySeriesType object.
+  !<
   subroutine ConstructTimeArraySeries(newTas, filename)
-! ******************************************************************************
-! ConstructTimeArraySeries -- Allocate a new TimeArraySeriesType object.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(TimeArraySeriesType), pointer, intent(out) :: newTas
     character(len=*), intent(in) :: filename
     ! -- local
     logical :: lex
-! ------------------------------------------------------------------------------
-    ! formats
+    ! -- formats
 10  format('Error: Time-array-series file "', a, '" does not exist.')
     !
     ! -- Allocate a new object of type TimeArraySeriesType
@@ -81,22 +77,19 @@ subroutine ConstructTimeArraySeries(newTas, filename)
     end if
     newTas%datafile = filename
     !
+    ! -- Return
     return
   end subroutine ConstructTimeArraySeries
 
   ! -- Public procedures
 
-  subroutine tas_init(this, fname, dis, iout, tasname, autoDeallocate)
-! ******************************************************************************
-! tas_init -- initialize the time array series
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Initialize the time array series
+  !<
+  subroutine tas_init(this, fname, modelname, iout, tasname, autoDeallocate)
     ! -- dummy
     class(TimeArraySeriesType), intent(inout) :: this
     character(len=*), intent(in) :: fname
-    class(DisBaseType), pointer, intent(inout) :: dis
+    character(len=*), intent(in) :: modelname
     integer(I4B), intent(in) :: iout
     character(len=*), intent(inout) :: tasname
     logical, optional, intent(in) :: autoDeallocate
@@ -106,7 +99,6 @@ subroutine tas_init(this, fname, dis, iout, tasname, autoDeallocate)
     integer(I4B) :: inunit
     character(len=40) :: keyword, keyvalue
     logical :: found, continueread, endOfBlock
-! ------------------------------------------------------------------------------
     !
     ! -- initialize some variables
     if (present(autoDeallocate)) this%autoDeallocate = autoDeallocate
@@ -114,7 +106,7 @@ subroutine tas_init(this, fname, dis, iout, tasname, autoDeallocate)
     allocate (this%list)
     !
     ! -- assign members
-    this%dis => dis
+    this%modelname = modelname
     this%iout = iout
     !
     ! -- open time-array series input file
@@ -213,17 +205,14 @@ subroutine tas_init(this, fname, dis, iout, tasname, autoDeallocate)
       call this%parser%StoreErrorUnit()
     end if
     !
+    ! -- Return
     return
   end subroutine tas_init
 
+  !> @brief Populate an array time-weighted average value for a specified time
+  !! span
+  !<
   subroutine GetAverageValues(this, nvals, values, time0, time1)
-! ******************************************************************************
-! GetAverageValues -- populate an array time-weighted average value for a
-!   specified time span.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeArraySeriesType), intent(inout) :: this
     integer(I4B), intent(in) :: nvals
@@ -233,7 +222,6 @@ subroutine GetAverageValues(this, nvals, values, time0, time1)
     ! -- local
     integer(I4B) :: i
     real(DP) :: timediff
-! ------------------------------------------------------------------------------
     !
     timediff = time1 - time0
     if (timediff > 0) then
@@ -246,36 +234,29 @@ subroutine GetAverageValues(this, nvals, values, time0, time1)
       call this%get_values_at_time(nvals, values, time0)
     end if
     !
+    ! -- Return
     return
   end subroutine GetAverageValues
 
+  !> @brief Return unit number
+  !<
   function GetInunit(this)
-! ******************************************************************************
-! GetInunit -- return unit number
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     integer(I4B) :: GetInunit
     ! -- dummy
     class(TimeArraySeriesType) :: this
-! ------------------------------------------------------------------------------
     !
     GetInunit = this%inunit
     !
+    ! -- Return
     return
   end function GetInunit
 
   ! -- Private procedures
 
+  !> @brief Get surrounding records
+  !<
   subroutine get_surrounding_records(this, time, taEarlier, taLater)
-! ******************************************************************************
-! get_surrounding_records -- get_surrounding_records
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeArraySeriesType), intent(inout) :: this
     real(DP), intent(in) :: time
@@ -288,7 +269,6 @@ subroutine get_surrounding_records(this, time, taEarlier, taLater)
     type(ListNodeType), pointer :: node1 => null()
     type(TimeArrayType), pointer :: ta => null(), ta0 => null(), ta1 => null()
     class(*), pointer :: obj
-! ------------------------------------------------------------------------------
     !
     taEarlier => null()
     taLater => null()
@@ -361,38 +341,49 @@ subroutine get_surrounding_records(this, time, taEarlier, taLater)
     if (time0 <= time) taEarlier => ta0
     if (time1 >= time) taLater => ta1
     !
+    ! -- Return
     return
   end subroutine get_surrounding_records
 
+  !> @brief Read next time array from input file and append to list
+  !<
   logical function read_next_array(this)
-! ******************************************************************************
-! read_next_array -- Read next time array from input file and append to list.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- modules
+    use ConstantsModule, only: LENMEMPATH
+    use MemoryManagerModule, only: mem_setptr
+    use MemoryHelperModule, only: create_mem_path
     ! -- dummy
     class(TimeArraySeriesType), intent(inout) :: this
     ! -- local
-    integer(I4B) :: i, ierr, istart, istat, istop, lloc, nrow, ncol, nodesperlayer
+    integer(I4B) :: i, ierr, istart, istat, istop, lloc, nrow, ncol, &
+                    nodesperlayer
     logical :: lopen, isFound
     type(TimeArrayType), pointer :: ta => null()
-! ------------------------------------------------------------------------------
+    character(len=LENMEMPATH) :: mempath
+    integer(I4B), dimension(:), contiguous, pointer :: mshape
     !
+    ! -- initialize
     istart = 1
     istat = 0
     istop = 1
     lloc = 1
+    nullify (mshape)
+    !
+    ! -- create mempath
+    mempath = create_mem_path(component=this%modelname, subcomponent='DIS')
+    !
+    ! -- set mshape pointer
+    call mem_setptr(mshape, 'MSHAPE', mempath)
+    !
     ! Get dimensions for supported discretization type
-    if (this%dis%supports_layers()) then
-      nodesperlayer = this%dis%get_ncpl()
-      if (size(this%dis%mshape) == 3) then
-        nrow = this%dis%mshape(2)
-        ncol = this%dis%mshape(3)
-      else
-        nrow = 1
-        ncol = this%dis%mshape(2)
-      end if
+    if (size(mshape) == 2) then
+      nodesperlayer = mshape(2)
+      nrow = 1
+      ncol = mshape(2)
+    else if (size(mshape) == 3) then
+      nodesperlayer = mshape(2) * mshape(3)
+      nrow = mshape(2)
+      ncol = mshape(3)
     else
       errmsg = 'Time array series is not supported for selected &
                &discretization type.'
@@ -403,7 +394,7 @@ logical function read_next_array(this)
     read_next_array = .false.
     inquire (unit=this%inunit, opened=lopen)
     if (lopen) then
-      call ConstructTimeArray(ta, this%dis)
+      call ConstructTimeArray(ta, this%modelname)
       ! -- read a time and an array from the input file
       ! -- Get a TIME block and read the time
       call this%parser%GetBlock('TIME', isFound, ierr, &
@@ -412,7 +403,7 @@ logical function read_next_array(this)
         ta%taTime = this%parser%GetDouble()
         ! -- Read the array
         call ReadArray(this%parser%iuactive, ta%taArray, this%Name, &
-                       this%dis%ndim, ncol, nrow, 1, nodesperlayer, &
+                       size(mshape), ncol, nrow, 1, nodesperlayer, &
                        this%iout, 0, 0)
         !
         ! -- multiply values by sfac
@@ -428,19 +419,15 @@ logical function read_next_array(this)
         call this%parser%terminateblock()
       end if
     end if
-    return ! Normal return
     !
+    ! -- Return
     return
   end function read_next_array
 
+  !> @brief Return an array of values for a specified time, same units as
+  !! time-series values
+  !<
   subroutine get_values_at_time(this, nvals, values, time)
-! ******************************************************************************
-! get_values_at_time -- Return an array of values for a specified time, same
-!   units as time-series values.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeArraySeriesType), intent(inout) :: this
     integer(I4B), intent(in) :: nvals
@@ -452,10 +439,9 @@ subroutine get_values_at_time(this, nvals, values, time)
                 valdiff
     type(TimeArrayType), pointer :: taEarlier => null()
     type(TimeArrayType), pointer :: taLater => null()
-    ! formats
+    ! -- formats
 10  format('Error getting array at time ', g10.3, &
            ' for time-array series "', a, '"')
-! ------------------------------------------------------------------------------
     !
     ierr = 0
     call this%get_surrounding_records(time, taEarlier, taLater)
@@ -488,7 +474,7 @@ subroutine get_values_at_time(this, nvals, values, time)
           ierr = 1
         end if
       else
-        if (is_same(taEarlier%taTime, time)) then
+        if (is_close(taEarlier%taTime, time)) then
           values = taEarlier%taArray
         else
           ! -- Only earlier time is available, and it is not time of interest;
@@ -502,7 +488,7 @@ subroutine get_values_at_time(this, nvals, values, time)
       end if
     else
       if (associated(taLater)) then
-        if (is_same(taLater%taTime, time)) then
+        if (is_close(taLater%taTime, time)) then
           values = taLater%taArray
         else
           ! -- only later time is available, and it is not time of interest
@@ -521,17 +507,15 @@ subroutine get_values_at_time(this, nvals, values, time)
       call store_error_unit(this%inunit)
     end if
     !
+    ! -- Return
     return
   end subroutine get_values_at_time
 
+  !> @brief Populates an array with integrated values for a specified time span
+  !!
+  !! Units: (ts-value-unit)*time
+  !<
   subroutine get_integrated_values(this, nvals, values, time0, time1)
-! ******************************************************************************
-! get_integrated_values -- Populates an array with integrated values for a
-!    specified time span.  Units: (ts-value-unit)*time
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeArraySeriesType), intent(inout) :: this
     integer(I4B), intent(in) :: nvals
@@ -551,7 +535,6 @@ subroutine get_integrated_values(this, nvals, values, time0, time1)
 10  format('Error encountered while performing integration', &
            ' for time-array series "', a, '" for time interval: ', &
            g12.5, ' to ', g12.5)
-! ------------------------------------------------------------------------------
     !
     values = DZERO
     value = DZERO
@@ -657,17 +640,14 @@ subroutine get_integrated_values(this, nvals, values, time0, time1)
       end if
     end if
     !
+    ! -- Return
     return
   end subroutine get_integrated_values
 
+  !> @brief Deallocate fromNode and all previous nodes in list;
+  !! reassign firstNode
+  !<
   subroutine DeallocateBackward(this, fromNode)
-! ******************************************************************************
-! DeallocateBackward -- Deallocate fromNode and all previous nodes in list;
-!   reassign firstNode.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeArraySeriesType), intent(inout) :: this
     type(ListNodeType), pointer, intent(inout) :: fromNode
@@ -677,7 +657,6 @@ subroutine DeallocateBackward(this, fromNode)
     type(ListNodeType), pointer :: prev => null()
     type(TimeArrayType), pointer :: ta => null()
     class(*), pointer :: obj => null()
-! ------------------------------------------------------------------------------
     !
     if (associated(fromNode)) then
       ! -- reassign firstNode
@@ -701,17 +680,14 @@ subroutine DeallocateBackward(this, fromNode)
       fromNode => null()
     end if
     !
+    ! -- Return
     return
   end subroutine DeallocateBackward
 
+  !> @brief Return pointer to ListNodeType object for the node representing
+  !! the latest preceding time in the time series
+  !<
   subroutine get_latest_preceding_node(this, time, tslNode)
-! ******************************************************************************
-! get_latest_preceding_node -- Return pointer to ListNodeType object for the
-!    node representing the latest preceding time in the time series
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeArraySeriesType), intent(inout) :: this
     real(DP), intent(in) :: time
@@ -723,7 +699,6 @@ subroutine get_latest_preceding_node(this, time, tslNode)
     type(TimeArrayType), pointer :: ta => null()
     type(TimeArrayType), pointer :: ta0 => null()
     class(*), pointer :: obj => null()
-! ------------------------------------------------------------------------------
     !
     tslNode => null()
     if (associated(this%list%firstNode)) then
@@ -742,7 +717,7 @@ subroutine get_latest_preceding_node(this, time, tslNode)
         if (associated(currNode%nextNode)) then
           obj => currNode%nextNode%GetItem()
           ta => CastAsTimeArrayType(obj)
-          if (ta%taTime < time .or. is_same(ta%taTime, time)) then
+          if (ta%taTime < time .or. is_close(ta%taTime, time)) then
             currNode => currNode%nextNode
           else
             exit
@@ -777,22 +752,18 @@ subroutine get_latest_preceding_node(this, time, tslNode)
     !
     if (time0 <= time) tslNode => node0
     !
+    ! -- Return
     return
   end subroutine get_latest_preceding_node
 
+  !> @brief Deallocate memory
+  !<
   subroutine tas_da(this)
-! ******************************************************************************
-! tas_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeArraySeriesType), intent(inout) :: this
     ! -- local
     integer :: i, n
     type(TimeArrayType), pointer :: ta => null()
-! ------------------------------------------------------------------------------
     !
     ! -- Deallocate contents of each time array in list
     n = this%list%Count()
@@ -805,23 +776,19 @@ subroutine tas_da(this)
     call this%list%Clear(.true.)
     deallocate (this%list)
     !
+    ! -- Return
     return
   end subroutine tas_da
 
   ! -- Procedures not type-bound
 
+  !> @brief Cast an unlimited polymorphic object as class(TimeArraySeriesType)
+  !<
   function CastAsTimeArraySeriesType(obj) result(res)
-! ******************************************************************************
-! CastAsTimeArraySeriesType -- Cast an unlimited polymorphic object as
-!   class(TimeArraySeriesType)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(*), pointer, intent(inout) :: obj
+    ! -- return
     type(TimeArraySeriesType), pointer :: res
-! ------------------------------------------------------------------------------
     !
     res => null()
     if (.not. associated(obj)) return
@@ -831,27 +798,25 @@ function CastAsTimeArraySeriesType(obj) result(res)
       res => obj
     end select
     !
+    ! -- Return
     return
   end function CastAsTimeArraySeriesType
 
+  !> @brief Get time array from list
+  !<
   function GetTimeArraySeriesFromList(list, indx) result(res)
-! ******************************************************************************
-! GetTimeArraySeriesFromList -- get time array from list
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(ListType), intent(inout) :: list
     integer, intent(in) :: indx
+    ! -- return
     type(TimeArraySeriesType), pointer :: res
     ! -- local
     class(*), pointer :: obj
-! ------------------------------------------------------------------------------
     !
     obj => list%GetItem(indx)
     res => CastAsTimeArraySeriesType(obj)
     !
+    ! -- Return
     return
   end function GetTimeArraySeriesFromList
 
diff --git a/src/Utilities/TimeSeries/TimeArraySeriesLink.f90 b/src/Utilities/TimeSeries/TimeArraySeriesLink.f90
index 4e1bb7d7a01..c697315dc3b 100644
--- a/src/Utilities/TimeSeries/TimeArraySeriesLink.f90
+++ b/src/Utilities/TimeSeries/TimeArraySeriesLink.f90
@@ -27,39 +27,33 @@ module TimeArraySeriesLinkModule
     real(DP), dimension(:), pointer, public :: BndArray => null()
     real(DP), dimension(:), pointer, public :: RMultArray => null()
     type(TimeArraySeriesType), pointer, public :: TimeArraySeries => null()
+
   contains
+
     procedure, public :: da => tasl_da
   end type TimeArraySeriesLinkType
 
 contains
 
+  !> @brief Deallocate
+  !<
   subroutine tasl_da(this)
-! ******************************************************************************
-! tasl_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeArraySeriesLinkType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
     this%nodelist => null()
     this%bndarray => null()
     this%rmultarray => null()
     this%TimeArraySeries => null()
     !
+    ! -- Return
     return
   end subroutine tasl_da
 
+  !> @brief Construct a time series of arrays that are linked
+  !<
   subroutine ConstructTimeArraySeriesLink(newTasLink, timeArraySeries, &
                                           pkgName, bndArray, iprpak, text)
-! ******************************************************************************
-! ConstructTimeArraySeriesLink -- construct
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(TimeArraySeriesLinkType), pointer, intent(out) :: newTasLink
     type(TimeArraySeriesType), pointer, intent(in) :: timeArraySeries
@@ -69,7 +63,6 @@ subroutine ConstructTimeArraySeriesLink(newTasLink, timeArraySeries, &
     character(len=*), intent(in) :: text
     ! -- local
     character(len=LENPACKAGENAME) :: pkgNameTemp
-! ------------------------------------------------------------------------------
     !
     allocate (newTasLink)
     ! Store package name as all caps
@@ -81,20 +74,17 @@ subroutine ConstructTimeArraySeriesLink(newTasLink, timeArraySeries, &
     newTasLink%Iprpak = iprpak
     newTasLink%Text = text
     !
+    ! -- Return
     return
   end subroutine ConstructTimeArraySeriesLink
 
+  !> @brief Cast an unlimited polymorphic object as TimeArraySeriesLinkType
+  !<
   function CastAsTimeArraySeriesLinkType(obj) result(res)
-! ******************************************************************************
-! CastAsTimeArraySeriesLinkType -- Cast an unlimited polymorphic object as
-!   TimeArraySeriesLinkType
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+    ! -- dummy
     class(*), pointer, intent(inout) :: obj
+    ! -- return
     type(TimeArraySeriesLinkType), pointer :: res
-! ------------------------------------------------------------------------------
     !
     res => null()
     if (.not. associated(obj)) return
@@ -104,47 +94,42 @@ function CastAsTimeArraySeriesLinkType(obj) result(res)
       res => obj
     end select
     !
+    ! -- Return
     return
   end function CastAsTimeArraySeriesLinkType
 
+  !> @brief Add time-array series to list
+  !<
   subroutine AddTimeArraySeriesLinkToList(list, tasLink)
-! ******************************************************************************
-! AddTimeArraySeriesLinkToList -- add to list
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(ListType), intent(inout) :: list
+    ! -- return
     type(TimeArraySeriesLinkType), pointer, intent(inout) :: tasLink
     ! -- local
     class(*), pointer :: obj
-! ------------------------------------------------------------------------------
     !
     obj => tasLink
     call list%Add(obj)
     !
+    ! -- Return
     return
   end subroutine AddTimeArraySeriesLinkToList
 
+  !> @brief Get time-array series from a list and return
+  !<
   function GetTimeArraySeriesLinkFromList(list, idx) result(res)
-! ******************************************************************************
-! GetTimeArraySeriesLinkFromList -- get from list
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(ListType), intent(inout) :: list
     integer(I4B), intent(in) :: idx
+    ! -- return
     type(TimeArraySeriesLinkType), pointer :: res
     ! -- local
     class(*), pointer :: obj
-! ------------------------------------------------------------------------------
     !
     obj => list%GetItem(idx)
     res => CastAsTimeArraySeriesLinkType(obj)
     !
+    ! -- Return
     return
   end function GetTimeArraySeriesLinkFromList
 
diff --git a/src/Utilities/TimeSeries/TimeArraySeriesManager.f90 b/src/Utilities/TimeSeries/TimeArraySeriesManager.f90
index 46040ca4cde..847126d0a0e 100644
--- a/src/Utilities/TimeSeries/TimeArraySeriesManager.f90
+++ b/src/Utilities/TimeSeries/TimeArraySeriesManager.f90
@@ -3,7 +3,7 @@ module TimeArraySeriesManagerModule
   use KindModule, only: DP, I4B
   use SimVariablesModule, only: errmsg
   use ConstantsModule, only: DZERO, LENTIMESERIESNAME, LINELENGTH, &
-                             LENHUGELINE
+                             LENHUGELINE, LENMODELNAME
   use ListModule, only: ListType
   use SimModule, only: store_error, store_error_unit
   use TdisModule, only: delt, totimc, kper, kstp
@@ -22,13 +22,16 @@ module TimeArraySeriesManagerModule
   type TimeArraySeriesManagerType
     ! -- Public members
     integer(I4B), public :: iout = 0 ! output unit num
-    class(DisBaseType), pointer, public :: dis => null() ! pointer to dis
+    class(DisBaseType), pointer :: dis => null() ! pointer to dis
+    character(len=LENMODELNAME) :: modelname
     ! -- Private members
     type(ListType), pointer, private :: boundTasLinks => null() ! list of TAS links
     character(len=LINELENGTH), allocatable, dimension(:) :: tasfiles ! list of TA file names
     type(TimeArraySeriesType), dimension(:), pointer, contiguous :: taslist ! array of TA pointers
     character(len=LENTIMESERIESNAME), allocatable, dimension(:) :: tasnames ! array of TA names
+
   contains
+
     ! -- Public procedures
     procedure, public :: tasmanager_df
     procedure, public :: ad => tasmgr_ad
@@ -49,41 +52,37 @@ module TimeArraySeriesManagerModule
 
   ! -- Public procedures
 
-  subroutine tasmanager_cr(this, dis, iout)
-! ******************************************************************************
-! tasmanager_cr -- create the tasmanager
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
+  !> @brief Create the time-array series manager
+  !<
+  subroutine tasmanager_cr(this, dis, modelname, iout)
     ! -- dummy
     type(TimeArraySeriesManagerType) :: this
-    class(DisBaseType), pointer :: dis
+    class(DisBaseType), pointer, optional :: dis
+    character(len=*), intent(in) :: modelname
     integer(I4B), intent(in) :: iout
-! ------------------------------------------------------------------------------
     !
+    if (present(dis)) then
+      this%dis => dis
+    end if
+    !
+    this%modelname = modelname
     this%iout = iout
-    this%dis => dis
     allocate (this%boundTasLinks)
     allocate (this%tasfiles(0))
     !
+    ! -- Return
     return
   end subroutine tasmanager_cr
 
+  !> @brief Define the time-array series manager
+  !<
   subroutine tasmanager_df(this)
-! ******************************************************************************
-! tasmanager_df -- define
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeArraySeriesManagerType) :: this
     ! -- local
     type(TimeArraySeriesType), pointer :: tasptr => null()
     integer(I4B) :: nfiles
     integer(I4B) :: i
-! ------------------------------------------------------------------------------
     !
     ! -- determine how many tasfiles.  This is the number of time array series
     !    so allocate arrays to store them
@@ -94,21 +93,19 @@ subroutine tasmanager_df(this)
     ! -- Setup a time array series for each file specified
     do i = 1, nfiles
       tasptr => this%taslist(i)
-      call tasptr%tas_init(this%tasfiles(i), this%dis, &
+      call tasptr%tas_init(this%tasfiles(i), this%modelname, &
                            this%iout, this%tasnames(i))
     end do
     !
+    ! -- Return
     return
   end subroutine tasmanager_df
 
+  !> @brief Time step (or subtime step) advance.
+  !!
+  !! Call this each time step or subtime step.
+  !<
   subroutine tasmgr_ad(this)
-! ******************************************************************************
-! tasmgr_ad -- time step (or subtime step) advance.
-!   Call this each time step or subtime step.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeArraySeriesManagerType) :: this
     ! -- local
@@ -116,13 +113,12 @@ subroutine tasmgr_ad(this)
     type(TimeArraySeriesType), pointer :: timearrayseries => null()
     integer(I4B) :: i, j, nlinks, nvals, isize1, isize2, inunit
     real(DP) :: begintime, endtime
-    ! formats
+    ! -- formats
     character(len=*), parameter :: fmt5 = &
       "(/,'Time-array-series controlled arrays in stress period ', &
       &i0, ', time step ', i0, ':')"
 10  format('"', a, '" package: ', a, ' array obtained from time-array series "', &
            a, '"')
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize time variables
     begintime = totimc
@@ -189,22 +185,18 @@ subroutine tasmgr_ad(this)
       end do
     end if
     !
+    ! -- Return
     return
   end subroutine tasmgr_ad
 
+  !> @brief Deallocate
+  !<
   subroutine tasmgr_da(this)
-! ******************************************************************************
-! tasmgr_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeArraySeriesManagerType) :: this
     ! -- local
     integer :: i, n
     type(TimeArraySeriesLinkType), pointer :: tasLink => null()
-! ------------------------------------------------------------------------------
     !
     ! -- Deallocate contents of each TimeArraySeriesType object in list
     !    of time-array series links.
@@ -232,16 +224,13 @@ subroutine tasmgr_da(this)
     this%dis => null()
     this%boundTasLinks => null()
     !
+    ! -- Return
     return
   end subroutine tasmgr_da
 
+  !> @brief Add a time-array series file
+  !<
   subroutine add_tasfile(this, fname)
-! ******************************************************************************
-! add_tasfile -- add a tas file
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use ArrayHandlersModule, only: ExpandArray
     ! -- dummy
@@ -249,32 +238,27 @@ subroutine add_tasfile(this, fname)
     character(len=*), intent(in) :: fname
     ! -- local
     integer(I4B) :: indx
-! ------------------------------------------------------------------------------
     !
     call ExpandArray(this%tasfiles, 1)
     indx = size(this%tasfiles)
     this%tasfiles(indx) = fname
     !
+    ! -- Return
     return
   end subroutine add_tasfile
 
+  !> @brief Zero out arrays that are represented with time series
+  !!
+  !! Delete all existing links from time array series to package arrays as they
+  !! will need to be created with a new BEGIN PERIOD block
+  !<
   subroutine Reset(this, pkgName)
-! ******************************************************************************
-! Reset -- zero out arrays that are represented with time series.
-!   Delete all existing links from time array series to package arrays as they
-!   will need to be created with a new BEGIN PERIOD block.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(TimeArraySeriesManagerType) :: this
     character(len=*), intent(in) :: pkgName
     ! -- local
     integer(I4B) :: i, j, nlinks
     type(TimeArraySeriesLinkType), pointer :: taslink
-! ------------------------------------------------------------------------------
     !
     ! -- Reassign all linked elements to zero
     nlinks = this%boundTasLinks%Count()
@@ -300,17 +284,14 @@ subroutine Reset(this, pkgName)
       end do
     end if
     !
+    ! -- Return
     return
   end subroutine Reset
 
+  !> @brief Make link from time-array series to package array
+  !<
   subroutine MakeTasLink(this, pkgName, bndArray, iprpak, &
                          tasName, text, convertFlux, nodelist, inunit)
-! ******************************************************************************
-! MakeTasLink -- Make link from TAS to package array
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeArraySeriesManagerType) :: this
     character(len=*), intent(in) :: pkgName
@@ -326,7 +307,6 @@ subroutine MakeTasLink(this, pkgName, bndArray, iprpak, &
     character(LINELENGTH) :: ermsg
     type(TimeArraySeriesLinkType), pointer :: newTasLink
     type(TimeArraySeriesType), pointer :: tasptr => null()
-! ------------------------------------------------------------------------------
     !
     ! -- Find the time array series
     nfiles = size(this%tasnames)
@@ -355,22 +335,18 @@ subroutine MakeTasLink(this, pkgName, bndArray, iprpak, &
     ! -- Add link to list of links
     call this%tasmgr_add_link(newTasLink)
     !
+    ! -- Return
     return
   end subroutine MakeTasLink
 
+  !> @brief Get link from the boundtaslinks list
+  !<
   function GetLink(this, indx) result(tasLink)
-! ******************************************************************************
-! GetLink -- get link from the boundtaslinks list
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeArraySeriesManagerType) :: this
     integer(I4B), intent(in) :: indx
+    ! -- return
     type(TimeArraySeriesLinkType), pointer :: tasLink
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     tasLink => null()
     !
@@ -378,21 +354,17 @@ function GetLink(this, indx) result(tasLink)
       tasLink => GetTimeArraySeriesLinkFromList(this%boundTasLinks, indx)
     end if
     !
+    ! -- Return
     return
   end function GetLink
 
+  !> @brief Count number of links in the boundtaslinks list
+  !<
   function CountLinks(this)
-! ******************************************************************************
-! CountLinks -- count number of links in the boundtaslinks list
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     integer(I4B) :: CountLinks
     ! -- dummy
     class(TimeArraySeriesManagerType) :: this
-! ------------------------------------------------------------------------------
     !
     if (associated(this%boundtaslinks)) then
       CountLinks = this%boundTasLinks%Count()
@@ -400,26 +372,30 @@ function CountLinks(this)
       CountLinks = 0
     end if
     !
+    ! -- Return
     return
   end function CountLinks
 
   ! -- Private procedures
 
+  !> @brief Convert the array from a flux to a flow rate by multiplying by the
+  !! cell area
+  !<
   subroutine tasmgr_convert_flux(this, tasLink)
-! ******************************************************************************
-! tasmgr_convert_flux -- convert the array from a flux to a flow rate by
-!   multiplying by the cell area
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeArraySeriesManagerType) :: this
     type(TimeArraySeriesLinkType), pointer, intent(inout) :: tasLink
     ! -- local
     integer(I4B) :: i, n, noder
     real(DP) :: area
-! ------------------------------------------------------------------------------
+    !
+    if (.not. (associated(this%dis) .and. &
+               associated(tasLink%nodelist))) then
+      errmsg = 'Programming error. Cannot convert flux. Verify that '&
+               &'a valid DIS instance and nodelist were provided.'
+      call store_error(errmsg)
+      call store_error_unit(tasLink%TimeArraySeries%GetInunit())
+    end if
     !
     n = size(tasLink%BndArray)
     do i = 1, n
@@ -430,24 +406,21 @@ subroutine tasmgr_convert_flux(this, tasLink)
       end if
     end do
     !
+    ! -- Return
     return
   end subroutine tasmgr_convert_flux
 
+  !> @brief Add a time arrays series link
+  !<
   subroutine tasmgr_add_link(this, tasLink)
-! ******************************************************************************
-! tasmgr_add_link -- add a time arrays series link
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeArraySeriesManagerType) :: this
     type(TimeArraySeriesLinkType), pointer :: tasLink
     ! -- local
-! ------------------------------------------------------------------------------
     !
     call AddTimeArraySeriesLinkToList(this%boundTasLinks, tasLink)
     !
+    ! -- Return
     return
   end subroutine tasmgr_add_link
 
diff --git a/src/Utilities/TimeSeries/TimeSeries.f90 b/src/Utilities/TimeSeries/TimeSeries.f90
index fa9af784796..b4a5d9d48f2 100644
--- a/src/Utilities/TimeSeries/TimeSeries.f90
+++ b/src/Utilities/TimeSeries/TimeSeries.f90
@@ -5,7 +5,7 @@ module TimeSeriesModule
   use ConstantsModule, only: LINELENGTH, UNDEFINED, STEPWISE, LINEAR, &
                              LINEAREND, LENTIMESERIESNAME, LENHUGELINE, &
                              DZERO, DONE, DNODATA
-  use GenericUtilitiesModule, only: is_same
+  use MathUtilModule, only: is_close
   use InputOutputModule, only: GetUnit, openfile, ParseLine, upcase
   use ListModule, only: ListType, ListNodeType
   use SimVariablesModule, only: errmsg
@@ -31,7 +31,9 @@ module TimeSeriesModule
     logical, public :: autoDeallocate = .true.
     type(ListType), pointer, private :: list => null()
     class(TimeSeriesFileType), pointer, private :: tsfile => null()
+
   contains
+
     ! -- Public procedures
     procedure, public :: AddTimeSeriesRecord
     procedure, public :: Clear
@@ -66,7 +68,9 @@ module TimeSeriesModule
     type(TimeSeriesType), dimension(:), &
       pointer, contiguous, public :: timeSeries => null()
     type(BlockParserType), pointer, public :: parser
+
   contains
+
     ! -- Public procedures
     procedure, public :: Count
     procedure, public :: Initializetsfile
@@ -85,35 +89,26 @@ module TimeSeriesModule
 
   ! -- non-type-bound procedures
 
+  !> @brief Construct time series file
+  !<
   subroutine ConstructTimeSeriesFile(newTimeSeriesFile)
-! ******************************************************************************
-! ConstructTimeSeriesFile -- construct ts tsfile
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(TimeSeriesFileType), pointer, intent(inout) :: newTimeSeriesFile
-! ------------------------------------------------------------------------------
     !
     allocate (newTimeSeriesFile)
     allocate (newTimeSeriesFile%parser)
+    !
+    ! -- Return
     return
   end subroutine ConstructTimeSeriesFile
 
+  !> @brief Cast an unlimited polymorphic object as class(TimeSeriesFileType)
+  !<
   function CastAsTimeSeriesFileType(obj) result(res)
-! ******************************************************************************
-! CastAsTimeSeriesFileType -- Cast an unlimited polymorphic object as
-!   class(TimeSeriesFileType)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(*), pointer, intent(inout) :: obj
     ! -- return
     type(TimeSeriesFileType), pointer :: res
-! ------------------------------------------------------------------------------
     !
     res => null()
     if (.not. associated(obj)) return
@@ -122,22 +117,18 @@ function CastAsTimeSeriesFileType(obj) result(res)
     type is (TimeSeriesFileType)
       res => obj
     end select
+    !
+    ! -- Return
     return
   end function CastAsTimeSeriesFileType
 
+  !> @brief Cast an unlimited polymorphic object as class(TimeSeriesFileType)
+  !<
   function CastAsTimeSeriesFileClass(obj) result(res)
-! ******************************************************************************
-! CastAsTimeSeriesFileClass -- Cast an unlimited polymorphic object as
-!   class(TimeSeriesFileType)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(*), pointer, intent(inout) :: obj
     ! -- return
     type(TimeSeriesFileType), pointer :: res
-! ------------------------------------------------------------------------------
     !
     res => null()
     if (.not. associated(obj)) return
@@ -146,43 +137,37 @@ function CastAsTimeSeriesFileClass(obj) result(res)
     class is (TimeSeriesFileType)
       res => obj
     end select
+    !
+    ! -- Return
     return
   end function CastAsTimeSeriesFileClass
 
+  !> @brief Add time series file to list
+  !<
   subroutine AddTimeSeriesFileToList(list, tsfile)
-! ******************************************************************************
-! AddTimeSeriesFileToList -- add to list
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(ListType), intent(inout) :: list
     class(TimeSeriesFileType), pointer, intent(inout) :: tsfile
     ! -- local
     class(*), pointer :: obj => null()
-! ------------------------------------------------------------------------------
     !
     obj => tsfile
     call list%Add(obj)
     !
+    ! -- Return
     return
   end subroutine AddTimeSeriesFileToList
 
+  !> @brief Get time series from list
+  !<
   function GetTimeSeriesFileFromList(list, idx) result(res)
-! ******************************************************************************
-! GetTimeSeriesFileFromList -- get from list
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(ListType), intent(inout) :: list
     integer(I4B), intent(in) :: idx
+    ! -- return
     type(TimeSeriesFileType), pointer :: res
     ! -- local
     class(*), pointer :: obj => null()
-! ------------------------------------------------------------------------------
     !
     obj => list%GetItem(idx)
     res => CastAsTimeSeriesFileType(obj)
@@ -191,24 +176,21 @@ function GetTimeSeriesFileFromList(list, idx) result(res)
       res => CastAsTimeSeriesFileClass(obj)
     end if
     !
+    ! -- Return
     return
   end function GetTimeSeriesFileFromList
 
+  !> @brief Compare two time series; if they are identical, return true
+  !<
   function SameTimeSeries(ts1, ts2) result(same)
-! ******************************************************************************
-! SameTimeSeries -- Compare two time series; if they are identical, return true.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(TimeSeriesType), intent(in) :: ts1
     type(TimeSeriesType), intent(in) :: ts2
+    ! -- return
     logical :: same
     ! -- local
     integer :: i, n1, n2
     type(TimeSeriesRecordType), pointer :: tsr1, tsr2
-! ------------------------------------------------------------------------------
     !
     same = .false.
     n1 = ts1%list%Count()
@@ -227,23 +209,21 @@ function SameTimeSeries(ts1, ts2) result(same)
     !
     same = .true.
     !
+    ! -- Return
     return
   end function SameTimeSeries
 
   ! Type-bound procedures of TimeSeriesType
 
+  !> @brief Get time series value
+  !!
+  !! If iMethod is STEPWISE or LINEAR:
+  !!     Return a time-weighted average value for a specified time span.
+  !! If iMethod is LINEAREND:
+  !!     Return value at time1. Time0 argument is ignored.
+  !! Units: (ts-value-unit)
+  !<
   function GetValue(this, time0, time1, extendToEndOfSimulation)
-! ******************************************************************************
-! GetValue -- get ts value
-!    If iMethod is STEPWISE or LINEAR:
-!        Return a time-weighted average value for a specified time span.
-!    If iMethod is LINEAREND:
-!        Return value at time1. Time0 argument is ignored.
-!    Units: (ts-value-unit)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: GetValue
     ! -- dummy
@@ -251,9 +231,8 @@ function GetValue(this, time0, time1, extendToEndOfSimulation)
     real(DP), intent(in) :: time0
     real(DP), intent(in) :: time1
     logical, intent(in), optional :: extendToEndOfSimulation
-    !
+    ! -- local
     logical :: extend
-! ------------------------------------------------------------------------------
     !
     if (present(extendToEndOfSimulation)) then
       extend = extendToEndOfSimulation
@@ -268,17 +247,15 @@ function GetValue(this, time0, time1, extendToEndOfSimulation)
       GetValue = this%get_value_at_time(time1, extend)
     end select
     !
+    ! -- Return
     return
   end function GetValue
 
+  !> @brief Initialize time series
+  !!
+  !! Open time-series file and read options and first time-series record.
+  !<
   subroutine initialize_time_series(this, tsfile, name, autoDeallocate)
-! ******************************************************************************
-! initialize_time_series -- initialize time series
-!    Open time-series file and read options and first time-series record.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesType), intent(inout) :: this
     class(TimeSeriesFileType), target :: tsfile
@@ -286,7 +263,6 @@ subroutine initialize_time_series(this, tsfile, name, autoDeallocate)
     logical, intent(in), optional :: autoDeallocate
     ! -- local
     character(len=LENTIMESERIESNAME) :: tsNameTemp
-! ------------------------------------------------------------------------------
     !
     ! -- Assign the time-series tsfile, name, and autoDeallocate
     this%tsfile => tsfile
@@ -308,16 +284,13 @@ subroutine initialize_time_series(this, tsfile, name, autoDeallocate)
       call store_error(errmsg, terminate=.TRUE.)
     end if
     !
+    ! -- Return
     return
   end subroutine initialize_time_series
 
+  !> @brief Get surrounding records
+  !<
   subroutine get_surrounding_records(this, time, tsrecEarlier, tsrecLater)
-! ******************************************************************************
-! get_surrounding_records -- get surrounding records
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesType), intent(inout) :: this
     real(DP), intent(in) :: time
@@ -331,7 +304,6 @@ subroutine get_surrounding_records(this, time, tsrecEarlier, tsrecLater)
     type(TimeSeriesRecordType), pointer :: tsr => null(), tsrec0 => null()
     type(TimeSeriesRecordType), pointer :: tsrec1 => null()
     class(*), pointer :: obj => null()
-! ------------------------------------------------------------------------------
     !
     tsrecEarlier => null()
     tsrecLater => null()
@@ -347,7 +319,7 @@ subroutine get_surrounding_records(this, time, tsrecEarlier, tsrecLater)
         if (associated(currNode%nextNode)) then
           obj => currNode%nextNode%GetItem()
           tsr => CastAsTimeSeriesRecordType(obj)
-          if (tsr%tsrTime < time .and. .not. is_same(tsr%tsrTime, time)) then
+          if (tsr%tsrTime < time .and. .not. is_close(tsr%tsrTime, time)) then
             currNode => currNode%nextNode
           else
             exit
@@ -384,7 +356,7 @@ subroutine get_surrounding_records(this, time, tsrecEarlier, tsrecLater)
       obj => tsNode1%GetItem()
       tsrec1 => CastAsTimeSeriesRecordType(obj)
       time1 = tsrec1%tsrTime
-      do while (time1 < time .and. .not. is_same(time1, time))
+      do while (time1 < time .and. .not. is_close(time1, time))
         if (associated(tsNode1%nextNode)) then
           tsNode1 => tsNode1%nextNode
           obj => tsNode1%GetItem()
@@ -401,21 +373,19 @@ subroutine get_surrounding_records(this, time, tsrecEarlier, tsrecLater)
       !
     end if
     !
-    if (time0 < time .or. is_same(time0, time)) tsrecEarlier => tsrec0
-    if (time1 > time .or. is_same(time1, time)) tsrecLater => tsrec1
+    if (time0 < time .or. is_close(time0, time)) tsrecEarlier => tsrec0
+    if (time1 > time .or. is_close(time1, time)) tsrecLater => tsrec1
     !
+    ! -- Return
     return
   end subroutine get_surrounding_records
 
+  !> @brief Get surrounding nodes
+  !!
+  !! This subroutine is for working with time series already entirely stored
+  !! in memory -- it does not read data from a file.
+  !<
   subroutine get_surrounding_nodes(this, time, nodeEarlier, nodeLater)
-! ******************************************************************************
-! get_surrounding_nodes -- get surrounding nodes
-!   This subroutine is for working with time series already entirely stored
-!   in memory -- it does not read data from a file.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesType), intent(inout) :: this
     real(DP), intent(in) :: time
@@ -431,7 +401,6 @@ subroutine get_surrounding_nodes(this, time, nodeEarlier, nodeLater)
     type(TimeSeriesRecordType), pointer :: tsrecEarlier
     type(TimeSeriesRecordType), pointer :: tsrecLater
     class(*), pointer :: obj => null()
-! ------------------------------------------------------------------------------
     !
     tsrecEarlier => null()
     tsrecLater => null()
@@ -449,7 +418,7 @@ subroutine get_surrounding_nodes(this, time, nodeEarlier, nodeLater)
         if (associated(currNode%nextNode)) then
           obj => currNode%nextNode%GetItem()
           tsr => CastAsTimeSeriesRecordType(obj)
-          if (tsr%tsrTime < time .and. .not. is_same(tsr%tsrTime, time)) then
+          if (tsr%tsrTime < time .and. .not. is_close(tsr%tsrTime, time)) then
             currNode => currNode%nextNode
           else
             exit
@@ -485,7 +454,7 @@ subroutine get_surrounding_nodes(this, time, nodeEarlier, nodeLater)
       obj => tsNode1%GetItem()
       tsrec1 => CastAsTimeSeriesRecordType(obj)
       time1 = tsrec1%tsrTime
-      do while (time1 < time .and. .not. is_same(time1, time))
+      do while (time1 < time .and. .not. is_close(time1, time))
         if (associated(tsNode1%nextNode)) then
           tsNode1 => tsNode1%nextNode
           obj => tsNode1%GetItem()
@@ -498,30 +467,26 @@ subroutine get_surrounding_nodes(this, time, nodeEarlier, nodeLater)
       !
     end if
     !
-    if (time0 < time .or. is_same(time0, time)) then
+    if (time0 < time .or. is_close(time0, time)) then
       tsrecEarlier => tsrec0
       nodeEarlier => tsNode0
     end if
-    if (time1 > time .or. is_same(time1, time)) then
+    if (time1 > time .or. is_close(time1, time)) then
       tsrecLater => tsrec1
       nodeLater => tsNode1
     end if
     !
+    ! -- Return
     return
   end subroutine get_surrounding_nodes
 
+  !> @brief Read next record
+  !!
+  !! Read next time-series record from input file
+  !<
   logical function read_next_record(this)
-! ******************************************************************************
-! read_next_record -- read next record
-!   Read next time-series record from input file.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesType), intent(inout) :: this
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- If we have already encountered the end of the TIMESERIES block, do not try to read any further
     if (this%tsfile%finishedReading) then
@@ -533,18 +498,16 @@ logical function read_next_record(this)
     if (.not. read_next_record) then
       this%tsfile%finishedReading = .true.
     end if
-    return
     !
+    ! -- Return
+    return
   end function read_next_record
 
+  !> @brief Get value for a time
+  !!
+  !! Return a value for a specified time, same units as time-series values
+  !<
   function get_value_at_time(this, time, extendToEndOfSimulation)
-! ******************************************************************************
-! get_value_at_time -- get value for a time
-!   Return a value for a specified time, same units as time-series values.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: get_value_at_time
     ! -- dummy
@@ -559,7 +522,6 @@ function get_value_at_time(this, time, extendToEndOfSimulation)
     type(TimeSeriesRecordType), pointer :: tsrLater => null()
     ! -- formats
 10  format('Error getting value at time ', g10.3, ' for time series "', a, '"')
-! ------------------------------------------------------------------------------
     !
     ierr = 0
     call this%get_surrounding_records(time, tsrEarlier, tsrLater)
@@ -590,7 +552,7 @@ function get_value_at_time(this, time, extendToEndOfSimulation)
           ierr = 1
         end if
       else
-        if (extendToEndOfSimulation .or. is_same(tsrEarlier%tsrTime, time)) then
+        if (extendToEndOfSimulation .or. is_close(tsrEarlier%tsrTime, time)) then
           get_value_at_time = tsrEarlier%tsrValue
         else
           ! -- Only earlier time is available, and it is not time of interest;
@@ -604,7 +566,7 @@ function get_value_at_time(this, time, extendToEndOfSimulation)
       end if
     else
       if (associated(tsrLater)) then
-        if (is_same(tsrLater%tsrTime, time)) then
+        if (is_close(tsrLater%tsrTime, time)) then
           get_value_at_time = tsrLater%tsrValue
         else
           ! -- only later time is available, and it is not time of interest
@@ -622,18 +584,16 @@ function get_value_at_time(this, time, extendToEndOfSimulation)
       call store_error(errmsg, terminate=.TRUE.)
     end if
     !
+    ! -- Return
     return
   end function get_value_at_time
 
+  !> @brief Get integrated value
+  !!
+  !! Return an integrated value for a specified time span.
+  !! Units: (ts-value-unit)*time
+  !<
   function get_integrated_value(this, time0, time1, extendToEndOfSimulation)
-! ******************************************************************************
-! get_integrated_value -- get integrated value
-!   Return an integrated value for a specified time span.
-!    Units: (ts-value-unit)*time
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: get_integrated_value
     ! -- dummy
@@ -653,7 +613,6 @@ function get_integrated_value(this, time0, time1, extendToEndOfSimulation)
     ! -- formats
 10  format('Error encountered while performing integration', &
            ' for time series "', a, '" for time interval: ', g12.5, ' to ', g12.5)
-! ------------------------------------------------------------------------------
     !
     value = DZERO
     ldone = .false.
@@ -665,7 +624,7 @@ function get_integrated_value(this, time0, time1, extendToEndOfSimulation)
         currObj => currNode%GetItem()
         currRecord => CastAsTimeSeriesRecordType(currObj)
         currTime = currRecord%tsrTime
-        if (is_same(currTime, time1)) then
+        if (is_close(currTime, time1)) then
           ! Current node time = time1 so should be ldone
           ldone = .true.
         elseif (currTime < time1) then
@@ -698,12 +657,12 @@ function get_integrated_value(this, time0, time1, extendToEndOfSimulation)
           if (lprocess) then
             ! -- determine lower and upper limits of time span of interest
             !    within current interval
-            if (currTime > time0 .or. is_same(currTime, time0)) then
+            if (currTime > time0 .or. is_close(currTime, time0)) then
               t0 = currTime
             else
               t0 = time0
             end if
-            if (nextTime < time1 .or. is_same(nextTime, time1)) then
+            if (nextTime < time1 .or. is_close(nextTime, time1)) then
               t1 = nextTime
             else
               t1 = time1
@@ -738,7 +697,7 @@ function get_integrated_value(this, time0, time1, extendToEndOfSimulation)
         ! -- Are we done yet?
         if (t1 > time1) then
           ldone = .true.
-        elseif (is_same(t1, time1)) then
+        elseif (is_close(t1, time1)) then
           ldone = .true.
         else
           ! -- We are not done yet
@@ -763,18 +722,17 @@ function get_integrated_value(this, time0, time1, extendToEndOfSimulation)
         end if
       end if
     end if
+    !
+    ! -- Return
     return
   end function get_integrated_value
 
+  !> @brief Get average value
+  !!
+  !! Return a time-weighted average value for a specified time span.
+  !! Units: (ts-value-unit)
+  !<
   function get_average_value(this, time0, time1, extendToEndOfSimulation)
-! ******************************************************************************
-! get_average_value -- get average value
-!   Return a time-weighted average value for a specified time span.
-!    Units: (ts-value-unit)
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     real(DP) :: get_average_value
     ! -- dummy
@@ -784,7 +742,6 @@ function get_average_value(this, time0, time1, extendToEndOfSimulation)
     logical, intent(in) :: extendToEndOfSimulation
     ! -- local
     real(DP) :: timediff, value, valueIntegrated
-! ------------------------------------------------------------------------------
     !
     timediff = time1 - time0
     if (timediff > 0) then
@@ -801,18 +758,16 @@ function get_average_value(this, time0, time1, extendToEndOfSimulation)
     end if
     get_average_value = value
     !
+    ! -- Return
     return
   end function get_average_value
 
+  !> @brief Get latest preceding node
+  !!
+  !! Return pointer to ListNodeType object for the node representing the
+  !! latest preceding time in the time series
+  !<
   subroutine get_latest_preceding_node(this, time, tslNode)
-! ******************************************************************************
-! get_latest_preceding_node -- get latest preceding node
-!   Return pointer to ListNodeType object for the node
-!   representing the latest preceding time in the time series
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesType), intent(inout) :: this
     real(DP), intent(in) :: time
@@ -824,7 +779,6 @@ subroutine get_latest_preceding_node(this, time, tslNode)
     type(TimeSeriesRecordType), pointer :: tsr => null()
     type(TimeSeriesRecordType), pointer :: tsrec0 => null()
     class(*), pointer :: obj => null()
-! ------------------------------------------------------------------------------
     !
     tslNode => null()
     if (associated(this%list%firstNode)) then
@@ -842,7 +796,7 @@ subroutine get_latest_preceding_node(this, time, tslNode)
         if (associated(currNode%nextNode)) then
           obj => currNode%nextNode%GetItem()
           tsr => CastAsTimeSeriesRecordType(obj)
-          if (tsr%tsrTime < time .or. is_same(tsr%tsrTime, time)) then
+          if (tsr%tsrTime < time .or. is_close(tsr%tsrTime, time)) then
             currNode => currNode%nextNode
           else
             exit
@@ -875,64 +829,52 @@ subroutine get_latest_preceding_node(this, time, tslNode)
       end do
     end if
     !
-    if (time0 < time .or. is_same(time0, time)) tslNode => tsNode0
+    if (time0 < time .or. is_close(time0, time)) tslNode => tsNode0
     !
+    ! -- Return
     return
   end subroutine get_latest_preceding_node
 
+  !> @brief Deallocate
+  !<
   subroutine ts_da(this)
-! ******************************************************************************
-! ts_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesType), intent(inout) :: this
-! ------------------------------------------------------------------------------
     !
     if (associated(this%list)) then
       call this%list%Clear(.true.)
       deallocate (this%list)
     end if
     !
+    ! -- Return
     return
   end subroutine ts_da
 
+  !> @brief Add ts record
+  !<
   subroutine AddTimeSeriesRecord(this, tsr)
-! ******************************************************************************
-! AddTimeSeriesRecord -- add ts record
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesType) :: this
     type(TimeSeriesRecordType), pointer, intent(inout) :: tsr
     ! -- local
     class(*), pointer :: obj => null()
-! ------------------------------------------------------------------------------
     !
     obj => tsr
     call this%list%Add(obj)
     !
+    ! -- Return
     return
   end subroutine AddTimeSeriesRecord
 
+  !> @brief Get current ts record
+  !<
   function GetCurrentTimeSeriesRecord(this) result(res)
-! ******************************************************************************
-! GetCurrentTimeSeriesRecord -- get current ts record
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesType) :: this
-    ! result
+    ! -- result
     type(TimeSeriesRecordType), pointer :: res
     ! -- local
     class(*), pointer :: obj => null()
-! ------------------------------------------------------------------------------
     !
     obj => null()
     res => null()
@@ -941,23 +883,19 @@ function GetCurrentTimeSeriesRecord(this) result(res)
       res => CastAsTimeSeriesRecordType(obj)
     end if
     !
+    ! -- Return
     return
   end function GetCurrentTimeSeriesRecord
 
+  !> @brief Get previous ts record
+  !<
   function GetPreviousTimeSeriesRecord(this) result(res)
-! ******************************************************************************
-! GetPreviousTimeSeriesRecord -- get previous ts record
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesType) :: this
-    ! result
+    ! -- result
     type(TimeSeriesRecordType), pointer :: res
     ! -- local
     class(*), pointer :: obj => null()
-! ------------------------------------------------------------------------------
     !
     obj => null()
     res => null()
@@ -966,23 +904,19 @@ function GetPreviousTimeSeriesRecord(this) result(res)
       res => CastAsTimeSeriesRecordType(obj)
     end if
     !
+    ! -- Return
     return
   end function GetPreviousTimeSeriesRecord
 
+  !> @brief Get next ts record
+  !<
   function GetNextTimeSeriesRecord(this) result(res)
-! ******************************************************************************
-! GetNextTimeSeriesRecord -- get next ts record
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesType) :: this
-    ! result
+    ! -- result
     type(TimeSeriesRecordType), pointer :: res
     ! -- local
     class(*), pointer :: obj => null()
-! ------------------------------------------------------------------------------
     !
     obj => null()
     res => null()
@@ -991,32 +925,28 @@ function GetNextTimeSeriesRecord(this) result(res)
       res => CastAsTimeSeriesRecordType(obj)
     end if
     !
+    ! -- Return
     return
   end function GetNextTimeSeriesRecord
 
+  !> @brief Get ts record
+  !<
   function GetTimeSeriesRecord(this, time, epsi) result(res)
-! ******************************************************************************
-! GetTimeSeriesRecord -- get ts record
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesType) :: this
     double precision, intent(in) :: time
     double precision, intent(in) :: epsi
-    ! result
+    ! -- result
     type(TimeSeriesRecordType), pointer :: res
     ! -- local
     type(TimeSeriesRecordType), pointer :: tsr
-! ------------------------------------------------------------------------------
     !
     call this%list%Reset()
     res => null()
     do
       tsr => this%GetNextTimeSeriesRecord()
       if (associated(tsr)) then
-        if (is_same(tsr%tsrTime, time)) then
+        if (is_close(tsr%tsrTime, time)) then
           res => tsr
           exit
         end if
@@ -1026,32 +956,25 @@ function GetTimeSeriesRecord(this, time, epsi) result(res)
       end if
     end do
     !
+    ! -- Return
     return
   end function GetTimeSeriesRecord
 
+  !> @brief Reset
+  !<
   subroutine Reset(this)
-! ******************************************************************************
-! Reset -- reset
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesType) :: this
-! ------------------------------------------------------------------------------
     !
     call this%list%Reset()
     !
+    ! -- Return
     return
   end subroutine Reset
 
+  !> @brief Insert a time series record
+  !<
   subroutine InsertTsr(this, tsr)
-! ******************************************************************************
-! InsertTsr -- insert ts record
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesType), intent(inout) :: this
     type(TimeSeriesRecordType), pointer, intent(inout) :: tsr
@@ -1060,7 +983,6 @@ subroutine InsertTsr(this, tsr)
     type(TimeSeriesRecordType), pointer :: tsrEarlier, tsrLater
     type(ListNodeType), pointer :: nodeEarlier, nodeLater
     class(*), pointer :: obj => null()
-! ------------------------------------------------------------------------------
     !
     badtime = -9.0d30
     time0 = badtime
@@ -1128,25 +1050,22 @@ subroutine InsertTsr(this, tsr)
       end if
     end if
     !
+    ! -- Return
     return
   end subroutine InsertTsr
 
+  !> @brief Find latest time
+  !<
   function FindLatestTime(this, readToEnd) result(endtime)
-! ******************************************************************************
-! FindLatestTime -- find latest time
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesType), intent(inout) :: this
     logical, intent(in), optional :: readToEnd
     ! -- local
     integer :: nrecords
-    double precision :: endtime
     type(TimeSeriesRecordType), pointer :: tsr
     class(*), pointer :: obj => null()
-! ------------------------------------------------------------------------------
+    ! -- return
+    double precision :: endtime
     !
     ! -- If the caller requested the very last time in the series (readToEnd is true), check that we have first read all records
     if (present(readToEnd)) then
@@ -1161,78 +1080,65 @@ function FindLatestTime(this, readToEnd) result(endtime)
     tsr => CastAsTimeSeriesRecordType(obj)
     endtime = tsr%tsrTime
     !
+    ! -- Return
     return
   end function FindLatestTime
 
+  !> @brief Clear the list of time series records
+  !<
   subroutine Clear(this, destroy)
-! ******************************************************************************
-! Clear -- Clear the list of time series records
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesType), intent(inout) :: this
     logical, optional, intent(in) :: destroy
-! ------------------------------------------------------------------------------
     !
     call this%list%Clear(destroy)
     !
+    ! -- Return
     return
   end subroutine Clear
 
 ! Type-bound procedures of TimeSeriesFileType
 
+  !> @brief Count number of time series
+  !<
   function Count(this)
-! ******************************************************************************
-! Count --count number of time series
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     integer(I4B) :: Count
     ! -- dummy
     class(TimeSeriesFileType) :: this
-! ------------------------------------------------------------------------------
     !
     if (associated(this%timeSeries)) then
       Count = size(this%timeSeries)
     else
       Count = 0
     end if
+    !
+    ! -- Return
     return
   end function Count
 
+  !> @brief Get time series
+  !<
   function GetTimeSeries(this, indx) result(res)
-! ******************************************************************************
-! GetTimeSeries -- get ts
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesFileType) :: this
     integer(I4B), intent(in) :: indx
-    ! result
+    ! -- return
     type(TimeSeriesType), pointer :: res
-! ------------------------------------------------------------------------------
     !
     res => null()
     if (indx > 0 .and. indx <= this%nTimeSeries) then
       res => this%timeSeries(indx)
     end if
+    !
+    ! -- Return
     return
   end function GetTimeSeries
 
+  !> @brief Open time-series tsfile file and read options and first record,
+  !! which may contain data to define multiple time series.
+  !<
   subroutine Initializetsfile(this, filename, iout, autoDeallocate)
-! ******************************************************************************
-! Initializetsfile -- Open time-series tsfile file and read options and first
-!   record, which may contain data to define multiple time series.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesFileType), target, intent(inout) :: this
     character(len=*), intent(in) :: filename
@@ -1248,7 +1154,6 @@ subroutine Initializetsfile(this, filename, iout, autoDeallocate)
     character(len=40) :: keyword, keyvalue
     character(len=:), allocatable :: line
     character(len=LENTIMESERIESNAME), allocatable, dimension(:) :: words
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize some variables
     if (present(autoDeallocate)) autoDeallocateLocal = autoDeallocate
@@ -1435,16 +1340,12 @@ subroutine Initializetsfile(this, filename, iout, autoDeallocate)
       call this%parser%StoreErrorUnit()
     end if
     !
+    ! -- Return
     return
   end subroutine Initializetsfile
 
+  !> @brief Read time series file line
   logical function read_tsfile_line(this)
-! ******************************************************************************
-! read_tsfile_line -- read tsfile line
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesFileType), intent(inout) :: this
     ! -- local
@@ -1452,7 +1353,6 @@ logical function read_tsfile_line(this)
     integer(I4B) :: i
     logical :: endOfBlock
     type(TimeSeriesRecordType), pointer :: tsRecord => null()
-! ------------------------------------------------------------------------------
     !
     read_tsfile_line = .false.
     !
@@ -1479,22 +1379,18 @@ logical function read_tsfile_line(this)
     end do tsloop
     read_tsfile_line = .true.
     !
+    ! -- Return
     return
   end function read_tsfile_line
 
+  !> @brief Deallocate memory
+  !<
   subroutine tsf_da(this)
-! ******************************************************************************
-! tsf_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesFileType), intent(inout) :: this
     ! -- local
     integer :: i, n
     type(TimeSeriesType), pointer :: ts => null()
-! ------------------------------------------------------------------------------
     !
     n = this%Count()
     do i = 1, n
@@ -1508,6 +1404,7 @@ subroutine tsf_da(this)
     deallocate (this%timeSeries)
     deallocate (this%parser)
     !
+    ! -- Return
     return
   end subroutine tsf_da
 
diff --git a/src/Utilities/TimeSeries/TimeSeriesFileList.f90 b/src/Utilities/TimeSeries/TimeSeriesFileList.f90
index f0dbd3a8f42..c7706af86cb 100644
--- a/src/Utilities/TimeSeries/TimeSeriesFileList.f90
+++ b/src/Utilities/TimeSeries/TimeSeriesFileList.f90
@@ -17,7 +17,9 @@ module TimeSeriesFileListModule
     ! -- Public members
     integer(I4B), public :: numtsfiles = 0
     type(ListType), public :: tsfileList
+
   contains
+
     ! -- Public procedures
     procedure, public :: Add
     procedure, public :: Counttsfiles
@@ -46,10 +48,11 @@ subroutine Add(this, filename, iout, tsfile)
     call ConstructTimeSeriesFile(tsf)
     tsfile => tsf
     call tsfile%Initializetsfile(filename, iout, .true.)
-
     !
     ! -- Add the time-series tsfile to the list
     call this%add_time_series_tsfile(tsfile)
+    !
+    ! -- Return
     return
   end subroutine Add
 
@@ -57,9 +60,10 @@ subroutine Clear(this)
     implicit none
     ! -- dummy
     class(TimeSeriesFileListType), intent(inout) :: this
-    ! -- local
     !
     call this%tsfileList%Clear()
+    !
+    ! -- Return
     return
   end subroutine Clear
 
@@ -72,6 +76,8 @@ function Counttsfiles(this)
     !
     Counttsfiles = this%tsfileList%Count()
     !
+    !
+    ! -- Return
     return
   end function Counttsfiles
 
@@ -94,6 +100,7 @@ function CountTimeSeries(this)
       end if
     end do
     !
+    ! -- Return
     return
   end function CountTimeSeries
 
@@ -102,11 +109,12 @@ function Gettsfile(this, indx) result(res)
     ! -- dummy
     class(TimeSeriesFileListType) :: this
     integer(I4B), intent(in) :: indx
-    ! result
+    ! -- return
     type(TimeSeriesFileType), pointer :: res
-    ! -- local
     !
     res => GetTimeSeriesFileFromList(this%tsfileList, indx)
+    !
+    ! -- Return
     return
   end function Gettsfile
 
@@ -117,10 +125,11 @@ subroutine add_time_series_tsfile(this, tsfile)
     ! -- dummy
     class(TimeSeriesFileListType), intent(inout) :: this
     class(TimeSeriesFileType), pointer, intent(inout) :: tsfile
-    ! -- local
     !
     call AddTimeSeriesFileToList(this%tsfileList, tsfile)
     this%numtsfiles = this%numtsfiles + 1
+    !
+    ! -- Return
     return
   end subroutine add_time_series_tsfile
 
@@ -139,6 +148,8 @@ subroutine tsfl_da(this)
     !
     call this%tsfileList%Clear(.true.)
     !
+    !
+    ! -- Return
     return
   end subroutine tsfl_da
 
diff --git a/src/Utilities/TimeSeries/TimeSeriesLink.f90 b/src/Utilities/TimeSeries/TimeSeriesLink.f90
index 6379be6daf6..16e5db971d4 100644
--- a/src/Utilities/TimeSeries/TimeSeriesLink.f90
+++ b/src/Utilities/TimeSeries/TimeSeriesLink.f90
@@ -37,6 +37,8 @@ module TimeSeriesLinkModule
 
 contains
 
+  !> @brief Construct time series link
+  !<
   subroutine ConstructTimeSeriesLink(newTsLink, timeSeries, pkgName, &
                                      auxOrBnd, bndElem, iRow, jCol, iprpak, &
                                      text)
@@ -70,13 +72,17 @@ subroutine ConstructTimeSeriesLink(newTsLink, timeSeries, pkgName, &
       newTsLink%Text = text
     end if
     !
+    ! -- Return
     return
   end subroutine ConstructTimeSeriesLink
 
+  !> @brief Cast an unlimited polymorphic object as TimeSeriesLinkType
+  !<
   function CastAsTimeSeriesLinkType(obj) result(res)
-    ! Cast an unlimited polymorphic object as TimeSeriesLinkType
     implicit none
+    ! -- dummy
     class(*), pointer, intent(inout) :: obj
+    ! -- return
     type(TimeSeriesLinkType), pointer :: res
     !
     res => null()
@@ -88,14 +94,19 @@ function CastAsTimeSeriesLinkType(obj) result(res)
     class default
       continue
     end select
+    !
+    ! -- Return
     return
   end function CastAsTimeSeriesLinkType
 
+  !> @brief Get time series link from a list
+  !<
   function GetTimeSeriesLinkFromList(list, indx) result(tsLink)
     implicit none
     ! -- dummy
     type(ListType), intent(inout) :: list
     integer(I4B), intent(in) :: indx
+    ! -- return
     type(TimeSeriesLinkType), pointer :: tsLink
     ! -- local
     class(*), pointer :: obj
@@ -104,9 +115,12 @@ function GetTimeSeriesLinkFromList(list, indx) result(tsLink)
     obj => list%GetItem(indx)
     tsLink => CastAsTimeSeriesLinkType(obj)
     !
+    ! -- Return
     return
   end function GetTimeSeriesLinkFromList
 
+  !> @brief Add time series link to a list
+  !<
   subroutine AddTimeSeriesLinkToList(list, tslink)
     implicit none
     ! -- dummy
@@ -118,6 +132,7 @@ subroutine AddTimeSeriesLinkToList(list, tslink)
     obj => tslink
     call list%Add(obj)
     !
+    ! -- Return
     return
   end subroutine AddTimeSeriesLinkToList
 
diff --git a/src/Utilities/TimeSeries/TimeSeriesManager.f90 b/src/Utilities/TimeSeries/TimeSeriesManager.f90
index 157564a863f..412cae25ce3 100644
--- a/src/Utilities/TimeSeries/TimeSeriesManager.f90
+++ b/src/Utilities/TimeSeries/TimeSeriesManager.f90
@@ -38,7 +38,9 @@ module TimeSeriesManagerModule
     type(HashTableType), pointer, private :: BndTsHashTable => null() ! hash of ts to tsobj
     type(TimeSeriesContainerType), allocatable, dimension(:), &
       private :: TsContainers
+
   contains
+
     ! -- Public procedures
     procedure, public :: tsmanager_df
     procedure, public :: ad => tsmgr_ad
@@ -55,20 +57,15 @@ module TimeSeriesManagerModule
 
 contains
 
+  !> @brief Create the tsmanager
+  !<
   subroutine tsmanager_cr(this, iout, removeTsLinksOnCompletion, &
                           extendTsToEndOfSimulation)
-! ******************************************************************************
-! tsmanager_cr -- create the tsmanager
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     type(TimeSeriesManagerType) :: this
     integer(I4B), intent(in) :: iout
     logical, intent(in), optional :: removeTsLinksOnCompletion
     logical, intent(in), optional :: extendTsToEndOfSimulation
-! ------------------------------------------------------------------------------
     !
     this%iout = iout
     if (present(removeTsLinksOnCompletion)) then
@@ -82,36 +79,27 @@ subroutine tsmanager_cr(this, iout, removeTsLinksOnCompletion, &
     allocate (this%tsfileList)
     allocate (this%tsfiles(1000))
     !
+    ! -- Return
     return
   end subroutine tsmanager_cr
 
+  !> @brief Define time series manager object
+  !<
   subroutine tsmanager_df(this)
-! ******************************************************************************
-! tsmanager_df -- define
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- modules
     ! -- dummy
     class(TimeSeriesManagerType) :: this
-! ------------------------------------------------------------------------------
     !
     if (this%numtsfiles > 0) then
       call this%HashBndTimeSeries()
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end subroutine tsmanager_df
 
+  !> @brief Add a time series file to this manager
+  !<
   subroutine add_tsfile(this, fname, inunit)
-! ******************************************************************************
-! add_tsfile -- add a time series file to this manager
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- modules
     use SimModule, only: store_error, store_error_unit
     use ArrayHandlersModule, only: ExpandArray
@@ -123,7 +111,6 @@ subroutine add_tsfile(this, fname, inunit)
     integer(I4B) :: isize
     integer(I4B) :: i
     class(TimeSeriesFileType), pointer :: tsfile => null()
-! ------------------------------------------------------------------------------
     !
     ! -- Check for fname duplicates
     if (this%numtsfiles > 0) then
@@ -146,17 +133,14 @@ subroutine add_tsfile(this, fname, inunit)
     ! --
     call this%tsfileList%Add(fname, this%iout, tsfile)
     !
+    ! -- Return
     return
   end subroutine add_tsfile
 
+  !> @brief Time step (or subtime step) advance. Call this each time step or
+  !! subtime step
+  !<
   subroutine tsmgr_ad(this)
-! ******************************************************************************
-! tsmgr_ad -- time step (or subtime step) advance. Call this each time step or
-!   subtime step.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesManagerType) :: this
     ! -- local
@@ -165,7 +149,7 @@ subroutine tsmgr_ad(this)
     integer(I4B) :: i, nlinks, nauxlinks
     real(DP) :: begintime, endtime, tsendtime
     character(len=LENPACKAGENAME + 2) :: pkgID
-    ! formats
+    ! -- formats
     character(len=*), parameter :: fmt5 = &
       "(/,'Time-series controlled values in stress period: ', i0, &
       &', time step ', i0, ':')"
@@ -177,7 +161,6 @@ subroutine tsmgr_ad(this)
            ' value from time series "', a, '" = ', g12.5)
 25  format(a, ' package: Boundary ', i0, ', ', a, &
            ' value from time series "', a, '" = ', g12.5, ' (', a, ')')
-! ------------------------------------------------------------------------------
     !
     ! -- Initialize time variables
     begintime = totimc
@@ -323,20 +306,16 @@ subroutine tsmgr_ad(this)
       end if
     end if
     !
+    ! -- Return
     return
   end subroutine tsmgr_ad
 
+  !> @brief Deallocate memory
+  !<
   subroutine tsmgr_da(this)
-! ******************************************************************************
-! tsmgr_da -- deallocate
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesManagerType) :: this
     ! -- local
-! ------------------------------------------------------------------------------
     !
     ! -- Deallocate time-series links in boundTsLinks
     call this%boundTsLinks%Clear(.true.)
@@ -357,24 +336,21 @@ subroutine tsmgr_da(this)
     !
     deallocate (this%tsfiles)
     !
+    ! -- Return
     return
   end subroutine tsmgr_da
 
+  !> @brief Call this when a new BEGIN PERIOD block is read for a new stress
+  !! period
+  !<
   subroutine Reset(this, pkgName)
-! ******************************************************************************
-! reset -- Call this when a new BEGIN PERIOD block is read for a new stress
-!    period.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesManagerType) :: this
     character(len=*), intent(in) :: pkgName
     ! -- local
     integer(I4B) :: i, nlinks
     type(TimeSeriesLinkType), pointer :: tslink
-! ------------------------------------------------------------------------------
+    !
     ! Zero out values for time-series controlled stresses.
     ! Also deallocate all tslinks too.
     ! Then when time series are
@@ -412,17 +388,14 @@ subroutine Reset(this, pkgName)
       end if
     end do
     !
+    ! -- Return
     return
   end subroutine Reset
 
+  !> @brief Make link
+  !<
   subroutine make_link(this, timeSeries, pkgName, auxOrBnd, bndElem, &
                        irow, jcol, iprpak, tsLink, text, bndName)
-! ******************************************************************************
-! make_link --
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesManagerType), intent(inout) :: this
     type(TimeSeriesType), pointer, intent(inout) :: timeSeries
@@ -434,8 +407,6 @@ subroutine make_link(this, timeSeries, pkgName, auxOrBnd, bndElem, &
     type(TimeSeriesLinkType), pointer, intent(inout) :: tsLink
     character(len=*), intent(in) :: text
     character(len=*), intent(in) :: bndName
-    ! -- local
-! ------------------------------------------------------------------------------
     !
     tsLink => null()
     call ConstructTimeSeriesLink(tsLink, timeSeries, pkgName, &
@@ -452,16 +423,13 @@ subroutine make_link(this, timeSeries, pkgName, auxOrBnd, bndElem, &
       tsLink%BndName = bndName
     end if
     !
+    ! -- Return
     return
   end subroutine make_link
 
+  !> @brief Get link
+  !<
   function GetLink(this, auxOrBnd, indx) result(tsLink)
-! ******************************************************************************
-! GetLink --
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesManagerType) :: this
     character(len=3), intent(in) :: auxOrBnd
@@ -469,7 +437,6 @@ function GetLink(this, auxOrBnd, indx) result(tsLink)
     type(TimeSeriesLinkType), pointer :: tsLink
     ! -- local
     type(ListType), pointer :: list
-! ------------------------------------------------------------------------------
     !
     list => null()
     tsLink => null()
@@ -485,22 +452,18 @@ function GetLink(this, auxOrBnd, indx) result(tsLink)
       tsLink => GetTimeSeriesLinkFromList(list, indx)
     end if
     !
+    ! -- Return
     return
   end function GetLink
 
+  !> @brief Count links
+  !<
   function CountLinks(this, auxOrBnd)
-! ******************************************************************************
-! CountLinks --
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- return
     integer(I4B) :: CountLinks
     ! -- dummy
     class(TimeSeriesManagerType) :: this
     character(len=3), intent(in) :: auxOrBnd
-! ------------------------------------------------------------------------------
     !
     CountLinks = 0
     if (auxOrBnd == 'BND') then
@@ -509,16 +472,13 @@ function CountLinks(this, auxOrBnd)
       CountLinks = this%auxvarTsLinks%count()
     end if
     !
+    ! -- Return
     return
   end function CountLinks
 
+  !> @brief Get time series
+  !<
   function get_time_series(this, name) result(res)
-! ******************************************************************************
-! get_time_series --
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesManagerType) :: this
     character(len=*), intent(in) :: name
@@ -526,35 +486,29 @@ function get_time_series(this, name) result(res)
     type(TimeSeriesType), pointer :: res
     ! -- local
     integer(I4B) :: indx
-! ------------------------------------------------------------------------------
     !
     ! Get index from hash table, get time series from TsContainers,
     !     and assign result to time series contained in link.
     res => null()
-    indx = this%BndTsHashTable%get_index(name)
+    indx = this%BndTsHashTable%get(name)
     if (indx > 0) then
       res => this%TsContainers(indx)%timeSeries
     end if
     !
+    ! -- Return
     return
   end function get_time_series
 
+  !> @brief Store all boundary (stress) time series links in TsContainers
+  !! and construct hash table BndTsHashTable
+  !<
   subroutine HashBndTimeSeries(this)
-! ******************************************************************************
-! HashBndTimeSeries --
-!   Store all boundary (stress) time series links in
-!   TsContainers and construct hash table BndTsHashTable.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     class(TimeSeriesManagerType), intent(inout) :: this
     ! -- local
     integer(I4B) :: i, j, k, numtsfiles, numts
     character(len=LENTIMESERIESNAME) :: name
     type(TimeSeriesFileType), pointer :: tsfile => null()
-! ------------------------------------------------------------------------------
     !
     ! Initialize the hash table
     call hash_table_cr(this%BndTsHashTable)
@@ -575,25 +529,21 @@ subroutine HashBndTimeSeries(this)
         this%TsContainers(k)%timeSeries => tsfile%GetTimeSeries(j)
         if (associated(this%TsContainers(k)%timeSeries)) then
           name = this%TsContainers(k)%timeSeries%Name
-          call this%BndTsHashTable%add_entry(name, k)
+          call this%BndTsHashTable%add(name, k)
         end if
       end do
     end do
     !
+    ! -- Return
     return
   end subroutine HashBndTimeSeries
 
   ! -- Non-type-bound procedures
 
+  !> @brief Call this subroutine if the time-series link is available or needed
+  !<
   subroutine read_value_or_time_series(textInput, ii, jj, bndElem, pkgName, &
                                        auxOrBnd, tsManager, iprpak, tsLink)
-! ******************************************************************************
-! read_value_or_time_series --
-!   Call this subroutine if the time-series link is available or needed.
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     character(len=*), intent(in) :: textInput
     integer(I4B), intent(in) :: ii
@@ -612,7 +562,6 @@ subroutine read_value_or_time_series(textInput, ii, jj, bndElem, pkgName, &
     character(len=LINELENGTH) :: errmsg
     character(len=LENTIMESERIESNAME) :: tsNameTemp
     logical :: found
-! ------------------------------------------------------------------------------
     !
     read (textInput, *, iostat=istat) r
     if (istat == 0) then
@@ -658,30 +607,28 @@ subroutine read_value_or_time_series(textInput, ii, jj, bndElem, pkgName, &
         call store_error(errmsg)
       end if
     end if
+    !
+    ! -- Return
+    return
   end subroutine read_value_or_time_series
 
+  !> @brief Call this subroutine from advanced packages to define timeseries
+  !! link for a variable (varName).
+  !!
+  !! Arguments are as follows:
+  !!    textInput    : string that is either a float or a string name
+  !!    ii           : column number
+  !!    jj           : row number
+  !!    bndElem      : pointer to a position in an array in package pkgName
+  !!    pkgName      : package name
+  !!    auxOrBnd     : 'AUX' or 'BND' keyword
+  !!    tsManager    : timeseries manager object for package
+  !!    iprpak       : integer flag indicating if interpolated timeseries values
+  !!                   should be printed to package iout during TsManager%ad()
+  !!    varName      : variable name
+  !<
   subroutine read_value_or_time_series_adv(textInput, ii, jj, bndElem, pkgName, &
                                            auxOrBnd, tsManager, iprpak, varName)
-! ******************************************************************************
-! read_value_or_time_series_adv -- Call this subroutine from advanced
-!    packages to define timeseries link for a variable (varName).
-!
-! -- Arguments are as follows:
-!       textInput    : string that is either a float or a string name
-!       ii           : column number
-!       jj           : row number
-!       bndElem      : pointer to a position in an array in package pkgName
-!       pkgName      : package name
-!       auxOrBnd     : 'AUX' or 'BND' keyword
-!       tsManager    : timeseries manager object for package
-!       iprpak       : integer flag indicating if interpolated timeseries values
-!                      should be printed to package iout during TsManager%ad()
-!       varName      : variable name
-!
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
     ! -- dummy
     character(len=*), intent(in) :: textInput
     integer(I4B), intent(in) :: ii
@@ -700,7 +647,6 @@ subroutine read_value_or_time_series_adv(textInput, ii, jj, bndElem, pkgName, &
     logical :: found
     type(TimeSeriesType), pointer :: timeseries => null()
     type(TimeSeriesLinkType), pointer :: tsLink => null()
-! ------------------------------------------------------------------------------
     !
     ! -- attempt to read textInput as a real value
     read (textInput, *, iostat=istat) v
@@ -751,28 +697,26 @@ subroutine read_value_or_time_series_adv(textInput, ii, jj, bndElem, pkgName, &
         call store_error(errmsg)
       end if
     end if
+    !
+    ! -- Return
     return
   end subroutine read_value_or_time_series_adv
-!
+
 ! -- private subroutines
+
+  !> @brief Remove an existing timeseries link if it is defined.
+  !!
+  !! Arguments are as follows:
+  !!    tsManager    : timeseries manager object for package
+  !!    ii           : column number
+  !!    jj           : row number
+  !!    pkgName      : package name
+  !!    auxOrBnd     : 'AUX' or 'BND' keyword
+  !!    varName      : variable name
+  !<
   function remove_existing_link(tsManager, ii, jj, &
                                 pkgName, auxOrBnd, varName) result(found)
-! ******************************************************************************
-! remove_existing_link -- remove an existing timeseries link if it is defined.
-!
-! -- Arguments are as follows:
-!       tsManager    : timeseries manager object for package
-!       ii           : column number
-!       jj           : row number
-!       pkgName      : package name
-!       auxOrBnd     : 'AUX' or 'BND' keyword
-!       varName      : variable name
-!
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- return variable
+    ! -- return
     logical :: found
     ! -- dummy
     type(TimeSeriesManagerType), intent(inout) :: tsManager
@@ -786,7 +730,6 @@ function remove_existing_link(tsManager, ii, jj, &
     integer(I4B) :: nlinks
     integer(I4B) :: removeLink
     type(TimeSeriesLinkType), pointer :: tslTemp => null()
-! ------------------------------------------------------------------------------
     !
     ! -- determine if link exists
     nlinks = tsManager%CountLinks(auxOrBnd)
@@ -818,25 +761,20 @@ function remove_existing_link(tsManager, ii, jj, &
       end if
     end if
     !
-    ! -- return
+    ! -- Return
     return
   end function remove_existing_link
 
+  !> @brief Determine if a timeseries link with varName is defined.
+  !!
+  !! Arguments are as follows:
+  !!    tsManager    : timeseries manager object for package
+  !!    pkgName      : package name
+  !!    varName      : variable name
+  !!    auxOrBnd     : optional 'AUX' or 'BND' keyword
+  !<
   function var_timeseries(tsManager, pkgName, varName, auxOrBnd) result(tsexists)
-! ******************************************************************************
-! var_timeseries -- determine if a timeseries link with varName is defined.
-!
-! -- Arguments are as follows:
-!       tsManager    : timeseries manager object for package
-!       pkgName      : package name
-!       varName      : variable name
-!       auxOrBnd     : optional 'AUX' or 'BND' keyword
-!
-! ******************************************************************************
-!
-!    SPECIFICATIONS:
-! ------------------------------------------------------------------------------
-    ! -- return variable
+    ! -- return
     logical :: tsexists
     ! -- dummy
     type(TimeSeriesManagerType), intent(inout) :: tsManager
@@ -848,7 +786,6 @@ function var_timeseries(tsManager, pkgName, varName, auxOrBnd) result(tsexists)
     integer(I4B) :: i
     integer(I4B) :: nlinks
     type(TimeSeriesLinkType), pointer :: tslTemp => null()
-! ------------------------------------------------------------------------------
     !
     ! -- process optional variables
     if (present(auxOrBnd)) then
@@ -874,7 +811,7 @@ function var_timeseries(tsManager, pkgName, varName, auxOrBnd) result(tsexists)
       end if
     end do csearchlinks
     !
-    ! -- return
+    ! -- Return
     return
   end function var_timeseries
 
diff --git a/src/Utilities/TimeSeries/TimeSeriesRecord.f90 b/src/Utilities/TimeSeries/TimeSeriesRecord.f90
index 8bfb1bc735c..17f6f6d35ca 100644
--- a/src/Utilities/TimeSeries/TimeSeriesRecord.f90
+++ b/src/Utilities/TimeSeries/TimeSeriesRecord.f90
@@ -15,22 +15,29 @@ module TimeSeriesRecordModule
 
 contains
 
+  !> @brief Allocate and assign members of a new TimeSeriesRecordType object
+  !<
   subroutine ConstructTimeSeriesRecord(newTsRecord, time, value)
-    ! Allocate and assign members of a new TimeSeriesRecordType object
     implicit none
+    ! -- dummy
     type(TimeSeriesRecordType), pointer, intent(out) :: newTsRecord
     real(DP), intent(in) :: time, value
     !
     allocate (newTsRecord)
     newTsRecord%tsrTime = time
     newTsRecord%tsrValue = value
+    !
+    ! -- Return
     return
   end subroutine ConstructTimeSeriesRecord
 
+  !> @brief Cast an unlimited polymorphic object as TimeSeriesRecordType
+  !<
   function CastAsTimeSeriesRecordType(obj) result(res)
-    ! Cast an unlimited polymorphic object as TimeSeriesRecordType
     implicit none
+    ! -- dummy
     class(*), pointer, intent(inout) :: obj
+    ! -- return
     type(TimeSeriesRecordType), pointer :: res
     !
     res => null()
@@ -40,9 +47,13 @@ function CastAsTimeSeriesRecordType(obj) result(res)
     type is (TimeSeriesRecordType)
       res => obj
     end select
+    !
+    ! -- Return
     return
   end function CastAsTimeSeriesRecordType
 
+  !> @brief Add time series record to list
+  !<
   subroutine AddTimeSeriesRecordToList(list, tsrecord)
     implicit none
     ! -- dummy
@@ -54,6 +65,7 @@ subroutine AddTimeSeriesRecordToList(list, tsrecord)
     obj => tsrecord
     call list%Add(obj)
     !
+    ! -- Return
     return
   end subroutine AddTimeSeriesRecordToList
 
diff --git a/src/Utilities/Timer.f90 b/src/Utilities/Timer.f90
index bac77230997..55c92761d17 100644
--- a/src/Utilities/Timer.f90
+++ b/src/Utilities/Timer.f90
@@ -2,7 +2,7 @@ module TimerModule
 
   use KindModule, only: DP, I4B
   use ConstantsModule, only: LINELENGTH, DZERO
-  use GenericUtilitiesModule, only: sim_message
+  use MessageModule, only: write_message
   implicit none
   private
   public :: print_start_time
@@ -32,7 +32,7 @@ subroutine print_start_time()
     ! -- Get current date and time, assign to IBDT, and write to screen
     call date_and_time(values=ibdt)
     write (line, fmtdt) (ibdt(i), i=1, 3), (ibdt(i), i=5, 7)
-    call sim_message(line, skipafter=1)
+    call write_message(line, skipafter=1)
     !
     ! -- return
     return
@@ -69,11 +69,11 @@ SUBROUTINE elapsed_time(iout, iprtim)
     !
     ! -- write elapsed time to stdout
     write (line, fmtdt) (IEDT(I), I=1, 3), (IEDT(I), I=5, 7)
-    call sim_message(line, skipbefore=1)
+    call write_message(line, skipbefore=1)
     !
     ! -- write elapsted time to iout
     IF (IPRTIM .GT. 0) THEN
-      call sim_message(line, iunit=iout, skipbefore=1)
+      call write_message(line, iunit=iout, skipbefore=1)
     END IF
 !
 !     Calculate elapsed time in days and seconds
@@ -145,7 +145,7 @@ SUBROUTINE elapsed_time(iout, iprtim)
       WRITE (line, 1040) NSECS, MSECS
 1040  FORMAT(1X, 'Elapsed run time: ', I2, '.', I3.3, ' Seconds')
     END IF
-    call sim_message(line, skipafter=1)
+    call write_message(line, skipafter=1)
 !
 !     Write times to file if requested
     IF (IPRTIM .GT. 0) THEN
diff --git a/src/Utilities/comarg.f90 b/src/Utilities/comarg.f90
index d8379d8888c..eaab198aab5 100644
--- a/src/Utilities/comarg.f90
+++ b/src/Utilities/comarg.f90
@@ -9,8 +9,8 @@ module CommandArguments
   use SimVariablesModule, only: istdout, isim_level, &
                                 simfile, simlstfile, simstdout, &
                                 isim_mode, simulation_mode
-  use GenericUtilitiesModule, only: sim_message, write_message
   use SimModule, only: store_error, ustop
+  use MessageModule, only: write_message, write_message_counter
   use InputOutputModule, only: upcase, getunit
   !
   implicit none
@@ -144,25 +144,25 @@ subroutine GetCommandLineArguments()
         lstop = .TRUE.
         write (line, '(2a,2(1x,a))') &
           trim(adjustl(cexe)), ':', trim(adjustl(VERSION))
-        call write_message(line, skipbefore=1, skipafter=1)
+        call write_message_counter(line, skipbefore=1, skipafter=1)
       case ('-DEV', '--DEVELOP')
         lstop = .TRUE.
         write (line, '(2a,g0)') &
           trim(adjustl(cexe)), ': develop version ', ltyp
-        call write_message(line, skipbefore=1, skipafter=1)
+        call write_message_counter(line, skipbefore=1, skipafter=1)
       case ('-C', '--COMPILER')
         lstop = .TRUE.
         call get_compiler(compiler)
         write (line, '(2a,1x,a)') &
           trim(adjustl(cexe)), ':', trim(adjustl(compiler))
-        call write_message(line, skipbefore=1, skipafter=1)
+        call write_message_counter(line, skipbefore=1, skipafter=1)
       case ('-S', '--SILENT')
         write (line, '(2a,1x,a)') &
           trim(adjustl(cexe)), ':', 'all screen output sent to mfsim.stdout'
-        call write_message(line, skipbefore=1, skipafter=1)
+        call write_message_counter(line, skipbefore=1, skipafter=1)
       case ('-D', '--DISCLAIMER')
         lstop = .TRUE.
-        call sim_message('', fmt=FMTDISCLAIMER)
+        call write_message('', fmt=FMTDISCLAIMER)
       case ('-P', '--PARALLEL')
         simulation_mode = 'PARALLEL'
       case ('-LIC', '--LICENSE')
@@ -171,7 +171,7 @@ subroutine GetCommandLineArguments()
       case ('-CO', '--COMPILER-OPT')
         lstop = .TRUE.
         call get_compile_options(coptions)
-        call write_message(coptions, skipbefore=1, skipafter=1)
+        call write_message_counter(coptions, skipbefore=1, skipafter=1)
       case ('-L', '--LEVEL')
         if (len_trim(clevel) < 1) then
           iarg = iarg + 1
@@ -195,7 +195,7 @@ subroutine GetCommandLineArguments()
         write (line, '(2a,2(1x,a))') &
           trim(adjustl(cexe)), ':', 'stdout output level', &
           trim(adjustl(clevel))
-        call write_message(line, skipbefore=1, skipafter=1)
+        call write_message_counter(line, skipbefore=1, skipafter=1)
       case ('-M', '--MODE')
         if (len_trim(cmode) < 1) then
           iarg = iarg + 1
@@ -217,7 +217,7 @@ subroutine GetCommandLineArguments()
                trim(adjustl(cmode))//'. Model input will be checked for all '// &
                'stress periods but the matrix equations will not be '// &
                'assembled or solved.'
-        call write_message(line, skipbefore=1, skipafter=1)
+        call write_message_counter(line, skipbefore=1, skipafter=1)
       case default
         lstop = .TRUE.
         call write_usage(trim(adjustl(header)), trim(adjustl(cexe)))
@@ -246,7 +246,7 @@ subroutine GetCommandLineArguments()
     !
     ! -- write blank line to stdout
     if (icountcmd > 0) then
-      call sim_message('')
+      call write_message('')
     end if
     !
     ! -- return
@@ -296,16 +296,16 @@ subroutine write_usage(header, cexe)
       &'[1] https://github.com/MODFLOW-USGS/modflow6/issues',/)"
     !
     ! -- write command line usage information to the screen
-    call sim_message(header)
+    call write_message(header)
     write (line, '(a,1x,a,15x,a,2(1x,a),2a)') &
       'usage:', cexe, 'run MODFLOW', trim(adjustl(MFVNAM)), &
       'using "', trim(adjustl(simfile)), '"'
-    call sim_message(line)
+    call write_message(line)
     write (line, '(a,1x,a,1x,a,5x,a)') &
       '   or:', cexe, '[options]', &
       'retrieve program information'
-    call sim_message(line)
-    call sim_message('', fmt=OPTIONSFMT)
+    call write_message(line)
+    call write_message('', fmt=OPTIONSFMT)
     !
     ! -- return
     return
diff --git a/src/Utilities/defmacro.F90 b/src/Utilities/defmacro.F90
index eef048079ec..c998b904bad 100644
--- a/src/Utilities/defmacro.F90
+++ b/src/Utilities/defmacro.F90
@@ -4,7 +4,7 @@ module DefinedMacros
   use ConstantsModule, only: OSUNDEF, OSLINUX, OSMAC, OSWIN
   implicit none
   private
-  public :: get_os, is_pro, using_petsc
+  public :: get_os, is_extended, using_petsc, using_netcdf
 contains
 
   !> @brief Get operating system
@@ -48,33 +48,47 @@ function get_os() result(ios)
     return
   end function get_os
 
-  !> @brief Determine if this is the professional version
+  !> @brief Determine if this is the extended version
   !!
   !! Function to get a logical indicating if this is the
-  !! professional version of MODFLOW.
+  !! extended version of MODFLOW.
   !!
-  !! @return      ispro                pro version logical
+  !! @return      isextended           extended version logical
   !<
-  function is_pro() result(ispro)
+  function is_extended() result(isextended)
+    ! -- return variables
+    logical(LGP) :: isextended !< extended version logical
     ! -- local variables
-    logical(LGP) :: ispro !< pro version logical
+    logical(LGP) :: ispetsc
+    logical(LGP) :: isnetcdf
+    !
+    ! -- initialize isextended
+    isextended = .FALSE.
     !
     ! -- check if using petsc
-    ispro = using_petsc()
+    ispetsc = using_petsc()
+    !
+    ! -- check if using netcf
+    isnetcdf = using_netcdf()
+    !
+    !
+    if (ispetsc .EQV. .TRUE. .OR. isnetcdf .EQV. .TRUE.) then
+      isextended = .TRUE.
+    end if
     !
     ! return
     return
-  end function is_pro
+  end function is_extended
 
   !> @brief Determine if using petsc
   !!
   !! Function to get a logical indicating if petsc is
   !! being used.
   !!
-  !! @return      petscavail                petsc used logical
+  !! @return      petscused                petsc used logical
   !<
   function using_petsc() result(petscused)
-    ! -- local variables
+    ! -- return variable
     logical(LGP) :: petscused !< petsc used logical
     !
     ! -- initialize petscavail
@@ -89,4 +103,27 @@ function using_petsc() result(petscused)
     return
   end function using_petsc
 
+  !> @brief Determine if using netcdf
+  !!
+  !! Function to get a logical indicating if netcdf is
+  !! being used.
+  !!
+  !! @return      netcdfused                netcdf used logical
+  !<
+  function using_netcdf() result(netcdfused)
+    ! -- return variable
+    logical(LGP) :: netcdfused !< netcdf used logical
+    !
+    ! -- initialize petscavail
+    netcdfused = .FALSE.
+    !
+    ! -- set operating system variables
+#ifdef __WITH_NETCDF__
+    netcdfused = .TRUE.
+#endif
+    !
+    ! return
+    return
+  end function using_netcdf
+
 end module DefinedMacros
diff --git a/src/Utilities/genericutils.f90 b/src/Utilities/genericutils.f90
deleted file mode 100644
index 549e3476d17..00000000000
--- a/src/Utilities/genericutils.f90
+++ /dev/null
@@ -1,413 +0,0 @@
-!> @brief This module contains generic utilties
-!!
-!! This module contains generic utilities that have
-!! limited dependencies.
-!!
-!<
-module GenericUtilitiesModule
-  use KindModule, only: DP, I4B, LGP
-  use ConstantsModule, only: MAXCHARLEN, LENHUGELINE, &
-                             DZERO, DPREC, DSAME, &
-                             LINELENGTH, LENHUGELINE, VSUMMARY
-  use SimVariablesModule, only: istdout, isim_level
-  !
-  implicit none
-
-  private
-
-  public :: sim_message
-  public :: write_message
-  public :: write_centered
-  public :: is_same
-  public :: stop_with_error
-
-contains
-
-  !> @brief Write simulation message
-  !!
-  !!  Subroutine to print message to user specified iunit or STDOUT based on level.
-  !!
-  !<
-  subroutine sim_message(message, iunit, fmt, level, &
-                         skipbefore, skipafter, advance)
-    ! -- dummy variables
-    character(len=*), intent(in) :: message !< message to write to iunit
-    integer(I4B), intent(in), optional :: iunit !< optional file unit to write the message to (default=stdout)
-    character(len=*), intent(in), optional :: fmt !< optional format to write the message (default='(a)')
-    integer(I4B), intent(in), optional :: level !< optional level for the message (default=summary)
-    integer(I4B), intent(in), optional :: skipbefore !< optional number of empty lines before message (default=0)
-    integer(I4B), intent(in), optional :: skipafter !< optional number of empty lines after message (default=0)
-    logical(LGP), intent(in), optional :: advance !< optional boolean indicating if advancing output (default is .TRUE.)
-    ! -- local variables
-    character(len=3) :: cadvance
-    integer(I4B) :: i
-    integer(I4B) :: ilen
-    integer(I4B) :: iu
-    integer(I4B) :: ilevel
-    character(len=LENHUGELINE) :: simfmt
-    character(len=*), parameter :: stdfmt = '(a)'
-    character(len=*), parameter :: emptyfmt = '()'
-    !
-    ! -- initialize local variables
-    ilen = len_trim(message)
-    !
-    ! -- process optional dummy variables
-    if (present(iunit)) then
-      iu = iunit
-    else
-      iu = istdout
-    end if
-    if (present(fmt)) then
-      simfmt = fmt
-    else
-      if (ilen > 0) then
-        simfmt = stdfmt
-      else
-        simfmt = emptyfmt
-      end if
-    end if
-    if (present(level)) then
-      ilevel = level
-    else
-      ilevel = VSUMMARY
-    end if
-    if (present(advance)) then
-      if (advance) then
-        cadvance = 'YES'
-      else
-        cadvance = 'NO'
-      end if
-    else
-      cadvance = 'YES'
-    end if
-    !
-    ! -- write empty line before message
-    if (present(skipbefore)) then
-      do i = 1, skipbefore
-        write (iu, *)
-      end do
-    end if
-    !
-    ! -- write message if the level of the message is less than
-    !    or equal the isim_level for the simulation
-    if (ilevel <= isim_level) then
-      if (ilen > 0) then
-        write (iu, trim(simfmt), advance=cadvance) message(1:ilen)
-      else
-        write (iu, trim(simfmt), advance=cadvance)
-      end if
-    end if
-    !
-    ! -- write empty line after message
-    if (present(skipafter)) then
-      do i = 1, skipafter
-        write (iu, *)
-      end do
-    end if
-    !
-    ! -- return
-    return
-  end subroutine sim_message
-
-  !> @brief Write messages
-  !!
-  !!  Subroutine that formats and writes a single message that
-  !!  may exceeed 78 characters in length. Messages longer than
-  !!  78 characters are written across multiple lines. When a
-  !!  counter is passed in subsequent lines are indented.
-  !!
-  !<
-  subroutine write_message(message, icount, iwidth, iunit, level, &
-                           skipbefore, skipafter)
-    ! -- dummy variables
-    character(len=*), intent(in) :: message !< message to be written
-    integer(I4B), intent(in), optional :: icount !< counter to prepended to the message
-    integer(I4B), intent(in), optional :: iwidth !< maximum width of the prepended counter
-    integer(I4B), intent(in), optional :: iunit !< the unit number to which the message is written
-    integer(I4B), intent(in), optional :: level !< level of message (VSUMMARY, VALL, VDEBUG)
-    integer(I4B), intent(in), optional :: skipbefore !< optional number of empty lines before message (default=0)
-    integer(I4B), intent(in), optional :: skipafter !< optional number of empty lines after message (default=0)
-    ! -- local variables
-    integer(I4B), parameter :: len_line = 78
-    character(len=LENHUGELINE) :: amessage
-    character(len=len_line) :: line
-    character(len=16) :: cfmt
-    character(len=10) :: counter
-    character(len=5) :: fmt_first
-    character(len=20) :: fmt_cont
-    logical(LGP) :: include_counter
-    integer(I4B) :: isb
-    integer(I4B) :: isa
-    integer(I4B) :: jend
-    integer(I4B) :: len_str1
-    integer(I4B) :: len_str2
-    integer(I4B) :: len_message
-    integer(I4B) :: junit
-    integer(I4B) :: ilevel
-    integer(I4B) :: i
-    integer(I4B) :: j
-    !
-    ! -- return if no message is passed
-    if (len_trim(message) < 1) then
-      return
-    end if
-    !
-    ! -- initialize local variables
-    amessage = message
-    counter = ''
-    fmt_first = '(A)'
-    fmt_cont = '(A)'
-    len_str1 = 0
-    len_str2 = len_line
-    include_counter = .FALSE.
-    junit = istdout
-    j = 0
-    !
-    ! -- process optional dummy variables
-    ! -- set the unit number
-    if (present(iunit)) then
-      if (iunit > 0) then
-        junit = iunit
-      end if
-    end if
-    !
-    ! -- set the message level
-    if (present(level)) then
-      ilevel = level
-    else
-      ilevel = VSUMMARY
-    end if
-    !
-    ! -- set skip before
-    if (present(skipbefore)) then
-      isb = skipbefore
-    else
-      isb = 0
-    end if
-    !
-    ! -- set skip after
-    if (present(skipafter)) then
-      isa = skipafter
-    else
-      isa = 0
-    end if
-    !
-    ! -- create the counter to prepend to the start of the message,
-    !    formats, and variables used to create strings
-    if (present(iwidth) .and. present(icount)) then
-      include_counter = .TRUE.
-      ! -- write counter
-      write (cfmt, '(A,I0,A)') '(1x,i', iwidth, ',".",1x)'
-      write (counter, cfmt) icount
-      ! -- calculate the length of the first and second string on a line
-      len_str1 = len(trim(counter)) + 1
-      len_str2 = len_line - len_str1
-      ! -- write format for the continuation lines
-      write (fmt_cont, '(a,i0,a)') &
-        '(', len(trim(counter)) + 1, 'x,a)'
-    end if
-    !
-    ! -- calculate the length of the message
-    len_message = len_trim(amessage)
-    !
-    ! -- parse the amessage into multiple lines
-5   continue
-    jend = j + len_str2
-    if (jend >= len_message) go to 100
-    do i = jend, j + 1, -1
-      if (amessage(i:i) .eq. ' ') then
-        if (j == 0) then
-          if (include_counter) then
-            line = counter(1:len_str1)//amessage(j + 1:i)
-          else
-            line = amessage(j + 1:i)
-          end if
-          call sim_message(line, iunit=junit, &
-                           fmt=fmt_first, level=ilevel, &
-                           skipbefore=isb)
-        else
-          line = adjustl(amessage(j + 1:i))
-          call sim_message(line, iunit=junit, &
-                           fmt=fmt_cont, level=ilevel)
-        end if
-        j = i
-        go to 5
-      end if
-    end do
-    if (j == 0) then
-      if (include_counter) then
-        line = counter(1:len_str1)//amessage(j + 1:jend)
-      else
-        line = amessage(j + 1:jend)
-      end if
-      call sim_message(line, iunit=junit, &
-                       fmt=fmt_first, level=ilevel, &
-                       skipbefore=isb)
-    else
-      line = amessage(j + 1:jend)
-      call sim_message(line, iunit=junit, &
-                       fmt=fmt_cont, level=ilevel)
-    end if
-    j = jend
-    go to 5
-    !
-    ! -- last piece of amessage to write to a line
-100 continue
-    jend = len_message
-    if (j == 0) then
-      if (include_counter) then
-        line = counter(1:len_str1)//amessage(j + 1:jend)
-      else
-        line = amessage(j + 1:jend)
-      end if
-      call sim_message(line, iunit=junit, &
-                       fmt=fmt_first, level=ilevel, &
-                       skipbefore=isb, skipafter=isa)
-    else
-      line = amessage(j + 1:jend)
-      call sim_message(line, iunit=junit, fmt=fmt_cont, &
-                       level=ilevel, &
-                       skipafter=isa)
-    end if
-    !
-    ! -- return
-    return
-  end subroutine write_message
-
-  !> @brief Write centered text
-  !!
-  !! Subroutine to write text to unit iunit centered in width defined by linelen.
-  !! Left-pad with blanks as needed.
-  !!
-  !<
-  subroutine write_centered(text, linelen, iunit)
-    ! -- dummy variables
-    character(len=*), intent(in) :: text !< message to write to iunit
-    integer(I4B), intent(in) :: linelen !< length of line to center text in
-    integer(I4B), intent(in), optional :: iunit !< optional file unit to write text (default=stdout)
-    ! -- local variables
-    character(len=linelen) :: line
-    character(len=linelen) :: blank
-    integer(I4B) :: iu
-    integer(I4B) :: len_message
-    integer(I4B) :: jend
-    integer(I4B) :: ipad
-    integer(I4B) :: i
-    integer(I4B) :: j
-    !
-    ! -- process optional parameters
-    if (present(iunit)) then
-      iu = iunit
-    else
-      iu = istdout
-    end if
-    !
-    ! -- process text
-    if (iu > 0) then
-      !
-      ! -- initialize local variables
-      blank = ''
-      len_message = len_trim(adjustl(text))
-      j = 0
-      !
-      ! -- parse the amessage into multiple lines
-5     continue
-      jend = j + linelen
-      if (jend >= len_message) go to 100
-      do i = jend, j + 1, -1
-        if (text(i:i) .eq. ' ') then
-          line = text(j + 1:i)
-          ipad = ((linelen - len_trim(line)) / 2)
-          call sim_message(blank(1:ipad)//line, iunit=iu)
-          j = i
-          go to 5
-        end if
-      end do
-      line = text(j + 1:jend)
-      ipad = ((linelen - len_trim(line)) / 2)
-      call sim_message(blank(1:ipad)//line, iunit=iu)
-      j = jend
-      go to 5
-      !
-      ! -- last piece of amessage to write to a line
-100   continue
-      jend = len_message
-      line = text(j + 1:jend)
-      ipad = ((linelen - len_trim(line)) / 2)
-      call sim_message(blank(1:ipad)//line, iunit=iu)
-    end if
-    !
-    ! -- return
-    return
-  end subroutine write_centered
-
-  !> @brief Function to determine if two reals are the same
-  !!
-  !! Function to evaluate if the difference between a and b are less than eps
-  !! (i.e. a and b are the same).
-  !!
-  !<
-  function is_same(a, b, eps) result(lvalue)
-    ! -- return variable
-    logical(LGP) :: lvalue !< boolean indicating if a and b are the same
-    ! -- dummy variables
-    real(DP), intent(in) :: a !< first number to evaluate
-    real(DP), intent(in) :: b !< second number to evaluate
-    real(DP), intent(in), optional :: eps !< optional maximum difference between a abd b (default=DSAME)
-    ! -- local variables
-    real(DP) :: epsloc
-    real(DP) :: denom
-    real(DP) :: rdiff
-    !
-    ! -- evaluate optioanl arguments
-    if (present(eps)) then
-      epsloc = eps
-    else
-      epsloc = DSAME
-    end if
-    lvalue = .FALSE.
-    if (a == b) then
-      lvalue = .TRUE.
-    else
-      if (abs(b) > abs(a)) then
-        denom = b
-      else
-        denom = a
-        if (abs(denom) == DZERO) then
-          denom = DPREC
-        end if
-      end if
-      rdiff = abs((a - b) / denom)
-      if (rdiff <= epsloc) then
-        lvalue = .TRUE.
-      end if
-    end if
-    !
-    ! -- return
-    return
-  end function is_same
-
-  !> @brief Subroutine to stop the program
-  !!
-  !! Subroutine to stop the program and issue the correct return code.
-  !!
-  !<
-  subroutine stop_with_error(ierr)
-    ! -- dummy variables
-    integer(I4B), intent(in), optional :: ierr !< optional error code to return (default=0)
-    ! -- local variables
-    integer(I4B) :: ireturn_err
-    !
-    ! -- process optional dummy variables
-    if (present(ierr)) then
-      ireturn_err = ierr
-    else
-      ireturn_err = 0
-    end if
-
-    ! -- return the correct return code
-    call exit(ireturn_err)
-
-  end subroutine stop_with_error
-
-end module GenericUtilitiesModule
diff --git a/src/Utilities/version.f90 b/src/Utilities/version.f90
index e9c4a685450..011f2ec6917 100644
--- a/src/Utilities/version.f90
+++ b/src/Utilities/version.f90
@@ -7,17 +7,18 @@
 module VersionModule
   ! -- module imports
   use KindModule
-  use DefinedMacros, only: is_pro, using_petsc
+  use DefinedMacros, only: is_extended, using_petsc, using_netcdf
   use ConstantsModule, only: LENBIGLINE, LENHUGELINE, DZERO
   use SimVariablesModule, only: istdout
-  use GenericUtilitiesModule, only: write_centered, write_message, sim_message
+  use MessageModule, only: write_message, write_message_centered, &
+                           write_message_counter
   use CompilerVersion, only: get_compiler, get_compile_options
   implicit none
   public
   ! -- modflow 6 version
-  integer(I4B), parameter :: IDEVELOPMODE = 0
-  character(len=*), parameter :: VERSIONNUMBER = '6.4.2'
-  character(len=*), parameter :: VERSIONTAG = ' 06/28/2023'
+  integer(I4B), parameter :: IDEVELOPMODE = 1
+  character(len=*), parameter :: VERSIONNUMBER = '6.4.3'
+  character(len=*), parameter :: VERSIONTAG = ' 02/07/2024'
   character(len=40), parameter :: VERSION = VERSIONNUMBER//VERSIONTAG
   character(len=2), parameter :: MFVNAM = ' 6'
   character(len=*), parameter :: MFTITLE = &
@@ -61,6 +62,16 @@ module VersionModule
   &'      and the PETSc Development Team All rights reserved.',/,&
   &'      (https://petsc.org/release/)',/&
   &)"
+  character(len=*), parameter :: NETCDFLICENSE = &
+  "(&
+  &'The following library is used in this USGS product:',//,&
+  &'    NetCDF, network Common Data Form software library',/,&
+  &'      Copyright (c) 1993-2014 University Corporation for Atmospheric',/,&
+  &'      Research/Unidata. Redistribution and use in source and binary',/,&
+  &'      forms, with or without modification, are permitted provided that',/,&
+  &'      the conditions in the NetCDF copyright are met',/,&
+  &'        (https://www.unidata.ucar.edu/software/netcdf/copyright.html)',/&
+  &)"
   ! -- disclaimer must be appropriate for version (release or release candidate)
   character(len=*), parameter :: FMTDISCLAIMER = &
     "(/,&
@@ -101,33 +112,40 @@ subroutine write_listfile_header(iout, cmodel_type, write_sys_command, &
     logical(LGP) :: wsc
     !
     ! -- set pro string
-    if (is_pro()) then
-      write (cheader, '(3a)') 'MODFLOW', MFVNAM, ' PROFESSIONAL'
+    if (is_extended()) then
+      write (cheader, '(3a)') 'MODFLOW', MFVNAM, ' EXTENDED'
     else
       write (cheader, '(2a)') 'MODFLOW', MFVNAM
     end if
     !
     ! -- Write title to iout
-    call write_centered(cheader, iheader_width, iunit=iout)
-    call write_centered(MFTITLE, iheader_width, iunit=iout)
+    call write_message_centered(text=cheader, linelen=iheader_width, &
+                                iunit=iout)
+    call write_message_centered(text=MFTITLE, linelen=iheader_width, &
+                                iunit=iout)
     !
     ! -- Write model type to list file
     if (present(cmodel_type)) then
-      call write_centered(cmodel_type, iheader_width, iunit=iout)
+      call write_message_centered(text=cmodel_type, linelen=iheader_width, &
+                                  iunit=iout)
     end if
     !
     ! -- Write version
-    call write_centered('VERSION '//VERSION, iheader_width, iunit=iout)
+    call write_message_centered(text='VERSION '//VERSION, &
+                                linelen=iheader_width, iunit=iout)
     !
     ! -- Write if develop mode
     if (IDEVELOPMODE == 1) then
-      call write_centered('***DEVELOP MODE***', iheader_width, iunit=iout)
+      call write_message_centered(text='***DEVELOP MODE***', &
+                                  linelen=iheader_width, iunit=iout)
     end if
     !
     ! -- Write compiler version
     call get_compiler(compiler)
-    call write_centered(' ', iheader_width, iunit=iout)
-    call write_centered(trim(adjustl(compiler)), iheader_width, iunit=iout)
+    call write_message_centered(text=' ', linelen=iheader_width, &
+                                iunit=iout)
+    call write_message_centered(text=trim(adjustl(compiler)), &
+                                linelen=iheader_width, iunit=iout)
     !
     ! -- Write disclaimer
     write (iout, FMTDISCLAIMER)
@@ -140,7 +158,7 @@ subroutine write_listfile_header(iout, cmodel_type, write_sys_command, &
     ! -- write compiler options
     if (iout /= istdout) then
       call get_compile_options(compiler_options)
-      call write_message(compiler_options, iunit=iout)
+      call write_message_counter(text=compiler_options, iunit=iout)
     end if
     !
     ! -- Write the system command used to initiate simulation
@@ -160,9 +178,7 @@ subroutine write_listfile_header(iout, cmodel_type, write_sys_command, &
       call write_kindinfo(iout)
     end if
     write (iout, *)
-    !
-    ! -- return
-    return
+
   end subroutine write_listfile_header
 
   !> @ brief Write program license
@@ -178,7 +194,16 @@ subroutine write_license(iout)
     if (present(iout)) then
       write (iout, FMTLICENSE)
     else
-      call sim_message('', fmt=FMTLICENSE)
+      call write_message('', fmt=FMTLICENSE)
+    end if
+    !
+    ! -- write NetCDF license
+    if (using_netcdf()) then
+      if (present(iout)) then
+        write (iout, NETCDFLICENSE)
+      else
+        call write_message('', fmt=NETCDFLICENSE)
+      end if
     end if
     !
     ! -- write PETSc license
@@ -186,12 +211,10 @@ subroutine write_license(iout)
       if (present(iout)) then
         write (iout, PETSCLICENSE)
       else
-        call sim_message('', fmt=PETSCLICENSE)
+        call write_message('', fmt=PETSCLICENSE)
       end if
     end if
-    !
-    ! -- return
-    return
+
   end subroutine write_license
 
 end module VersionModule
diff --git a/src/meson.build b/src/meson.build
index 5f57e065d7b..b25a391edb3 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -28,10 +28,14 @@ modflow_sources = files(
     'Exchange' / 'BaseExchange.f90',
     'Exchange' / 'DisConnExchange.f90',
     'Exchange' / 'GhostNode.f90',
+    'Exchange' / 'GwfExchangeMover.f90',
     'Exchange' / 'GwfGwfExchange.f90',
     'Exchange' / 'GwfGwtExchange.f90',
     'Exchange' / 'GwtGwtExchange.f90',
     'Exchange' / 'NumericalExchange.f90',
+    'Exchange' / 'gwfgwfidm.f90',
+    'Exchange' / 'gwfgwtidm.f90',
+    'Exchange' / 'gwtgwtidm.f90',
     'Model' / 'Connection' / 'ConnectionBuilder.f90',
     'Model' / 'Connection' / 'CellWithNbrs.f90',
     'Model' / 'Connection' / 'CsrUtils.f90',
@@ -50,6 +54,7 @@ modflow_sources = files(
     'Model' / 'GroundWaterFlow' / 'gwf3api8.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3buy8.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3chd8.f90',
+    'Model' / 'GroundWaterFlow' / 'gwf3chd8idm.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3csub8.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3dis8.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3dis8idm.f90',
@@ -58,10 +63,15 @@ modflow_sources = files(
     'Model' / 'GroundWaterFlow' / 'gwf3disv8.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3disv8idm.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3drn8.f90',
+    'Model' / 'GroundWaterFlow' / 'gwf3drn8idm.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3evt8.f90',
+    'Model' / 'GroundWaterFlow' / 'gwf3evt8idm.f90',
+    'Model' / 'GroundWaterFlow' / 'gwf3evta8idm.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3ghb8.f90',
+    'Model' / 'GroundWaterFlow' / 'gwf3ghb8idm.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3hfb8.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3ic8.f90',
+    'Model' / 'GroundWaterFlow' / 'gwf3ic8idm.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3idm.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3lak8.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3maw8.f90',
@@ -71,7 +81,10 @@ modflow_sources = files(
     'Model' / 'GroundWaterFlow' / 'gwf3obs8.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3oc8.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3rch8.f90',
+    'Model' / 'GroundWaterFlow' / 'gwf3rch8idm.f90',
+    'Model' / 'GroundWaterFlow' / 'gwf3rcha8idm.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3riv8.f90',
+    'Model' / 'GroundWaterFlow' / 'gwf3riv8idm.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3sfr8.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3sto8.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3tvbase8.f90',
@@ -80,53 +93,61 @@ modflow_sources = files(
     'Model' / 'GroundWaterFlow' / 'gwf3uzf8.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3vsc8.f90',
     'Model' / 'GroundWaterFlow' / 'gwf3wel8.f90',
+    'Model' / 'GroundWaterFlow' / 'gwf3wel8idm.f90',
     'Model' / 'GroundWaterTransport' / 'gwt1.f90',
-    'Model' / 'GroundWaterTransport' / 'gwt1adv1.f90',
-    'Model' / 'GroundWaterTransport' / 'gwt1apt1.f90',
     'Model' / 'GroundWaterTransport' / 'gwt1cnc1.f90',
+    'Model' / 'GroundWaterTransport' / 'gwt1cnc1idm.f90',
     'Model' / 'GroundWaterTransport' / 'gwt1dis1idm.f90',
     'Model' / 'GroundWaterTransport' / 'gwt1disu1idm.f90',
     'Model' / 'GroundWaterTransport' / 'gwt1disv1idm.f90',
     'Model' / 'GroundWaterTransport' / 'gwt1dsp1.f90',
     'Model' / 'GroundWaterTransport' / 'gwt1dsp1idm.f90',
-    'Model' / 'GroundWaterTransport' / 'gwt1fmi1.f90',
-    'Model' / 'GroundWaterTransport' / 'gwt1ic1.f90',
+    'Model' / 'GroundWaterTransport' / 'gwt1ic1idm.f90',
     'Model' / 'GroundWaterTransport' / 'gwt1idm.f90',
     'Model' / 'GroundWaterTransport' / 'gwt1ist1.f90',
     'Model' / 'GroundWaterTransport' / 'gwt1lkt1.f90',
     'Model' / 'GroundWaterTransport' / 'gwt1mst1.f90',
-    'Model' / 'GroundWaterTransport' / 'gwt1mvt1.f90',
     'Model' / 'GroundWaterTransport' / 'gwt1mwt1.f90',
-    'Model' / 'GroundWaterTransport' / 'gwt1obs1.f90',
-    'Model' / 'GroundWaterTransport' / 'gwt1oc1.f90',
     'Model' / 'GroundWaterTransport' / 'gwt1sft1.f90',
     'Model' / 'GroundWaterTransport' / 'gwt1src1.f90',
-    'Model' / 'GroundWaterTransport' / 'gwt1ssm1.f90',
     'Model' / 'GroundWaterTransport' / 'gwt1uzt1.f90',
     'Model' / 'ModelUtilities' / 'BoundaryPackage.f90',
+    'Model' / 'ModelUtilities' / 'BoundaryPackageExt.f90',
     'Model' / 'ModelUtilities' / 'Connections.f90',
     'Model' / 'ModelUtilities' / 'DiscretizationBase.f90',
     'Model' / 'ModelUtilities' / 'DisvGeom.f90',
+    'Model' / 'ModelUtilities' / 'FlowModelInterface.f90',
     'Model' / 'ModelUtilities' / 'GwfBuyInputData.f90',
     'Model' / 'ModelUtilities' / 'GwfMvrPeriodData.f90',
     'Model' / 'ModelUtilities' / 'GwfNpfOptions.f90',
     'Model' / 'ModelUtilities' / 'GwfStorageUtils.f90',
     'Model' / 'ModelUtilities' / 'GwfVscInputData.f90',
-    'Model' / 'ModelUtilities' / 'GwtAdvOptions.f90',
     'Model' / 'ModelUtilities' / 'GwtDspOptions.f90',
     'Model' / 'ModelUtilities' / 'GwtSpc.f90',
+    'Model' / 'ModelUtilities' / 'ModelPackageInput.f90',
     'Model' / 'ModelUtilities' / 'Mover.f90',
     'Model' / 'ModelUtilities' / 'PackageMover.f90',
     'Model' / 'ModelUtilities' / 'SfrCrossSectionManager.f90',
     'Model' / 'ModelUtilities' / 'SfrCrossSectionUtils.f90',
+    'Model' / 'ModelUtilities' / 'TspAdvOptions.f90',
     'Model' / 'ModelUtilities' / 'UzfCellGroup.f90',
     'Model' / 'ModelUtilities' / 'Xt3dAlgorithm.f90',
     'Model' / 'ModelUtilities' / 'Xt3dInterface.f90',
+    'Model' / 'TransportModel' / 'tsp1.f90',
+    'Model' / 'TransportModel' / 'tsp1adv1.f90',
+    'Model' / 'TransportModel' / 'tsp1apt1.f90',
+    'Model' / 'TransportModel' / 'tsp1fmi1.f90',
+    'Model' / 'TransportModel' / 'tsp1ic1.f90',
+    'Model' / 'TransportModel' / 'tsp1obs1.f90',
+    'Model' / 'TransportModel' / 'tsp1oc1.f90',
+    'Model' / 'TransportModel' / 'tsp1mvt1.f90',
+    'Model' / 'TransportModel' / 'tsp1ssm1.f90',
     'Model' / 'BaseModel.f90',
     'Model' / 'ExplicitModel.f90',
     'Model' / 'NumericalModel.f90',
     'Model' / 'NumericalPackage.f90',
-    'Model' / 'TransportModel.f90',
+    'Solution' / 'ConvergenceSummary.f90',
+    'Solution' / 'LinearMethods' / 'ImsLinearSettings.f90',
     'Solution' / 'LinearMethods' / 'ims8base.f90',
     'Solution' / 'LinearMethods' / 'ims8linear.f90',
     'Solution' / 'LinearMethods' / 'ims8reordering.f90',
@@ -147,17 +168,25 @@ modflow_sources = files(
     'Utilities' / 'ArrayRead' / 'Integer1dReader.f90',
     'Utilities' / 'ArrayRead' / 'Integer2dReader.f90',
     'Utilities' / 'ArrayRead' / 'LayeredArrayReader.f90',
+    'Utilities' / 'Idm' / 'BoundInputContext.f90',
     'Utilities' / 'Idm' / 'DefinitionSelect.f90',
+    'Utilities' / 'Idm' / 'IdmLoad.f90',
     'Utilities' / 'Idm' / 'IdmLogger.f90',
-    'Utilities' / 'Idm' / 'IdmSimulation.f90',
     'Utilities' / 'Idm' / 'InputDefinition.f90',
+    'Utilities' / 'Idm' / 'InputLoadType.f90',
     'Utilities' / 'Idm' / 'ModelPackageInputs.f90',
     'Utilities' / 'Idm' / 'ModflowInput.f90',
+    'Utilities' / 'Idm' / 'SourceCommon.f90',
+    'Utilities' / 'Idm' / 'SourceLoad.F90',
+    'Utilities' / 'Idm' / 'mf6blockfile' / 'AsciiInputLoadType.f90',
     'Utilities' / 'Idm' / 'mf6blockfile' / 'IdmMf6File.f90',
     'Utilities' / 'Idm' / 'mf6blockfile' / 'LoadMf6File.f90',
+    'Utilities' / 'Idm' / 'mf6blockfile' / 'StressGridInput.f90',
+    'Utilities' / 'Idm' / 'mf6blockfile' / 'StressListInput.f90',
     'Utilities' / 'Idm' / 'mf6blockfile' / 'StructArray.f90',
     'Utilities' / 'Idm' / 'mf6blockfile' / 'StructVector.f90',
     'Utilities' / 'Idm' / 'selector' / 'IdmDfnSelector.f90',
+    'Utilities' / 'Idm' / 'selector' / 'IdmExgDfnSelector.f90',
     'Utilities' / 'Idm' / 'selector' / 'IdmGwfDfnSelector.f90',
     'Utilities' / 'Idm' / 'selector' / 'IdmGwtDfnSelector.f90',
     'Utilities' / 'Idm' / 'selector' / 'IdmSimDfnSelector.f90',
@@ -201,7 +230,9 @@ modflow_sources = files(
     'Utilities' / 'compilerversion.F90',
     'Utilities' / 'Constants.f90',
     'Utilities' / 'defmacro.F90',
-    'Utilities' / 'genericutils.f90',
+    'Utilities' / 'DevFeature.f90',
+    'Utilities' / 'ErrorUtil.f90',
+    'Utilities' / 'GeomUtil.f90',
     'Utilities' / 'HashTable.f90',
     'Utilities' / 'HeadFileReader.f90',
     'Utilities' / 'InputOutput.f90',
@@ -209,6 +240,8 @@ modflow_sources = files(
     'Utilities' / 'kind.f90',
     'Utilities' / 'List.f90',
     'Utilities' / 'ListReader.f90',
+    'Utilities' / 'LongLineReader.f90',
+    'Utilities' / 'MathUtil.f90',
     'Utilities' / 'Message.f90',
     'Utilities' / 'OpenSpec.f90',
     'Utilities' / 'PackageBudget.f90',
@@ -236,7 +269,8 @@ modflow_petsc_sources = files(
   'Utilities' / 'Vector' / 'PetscVector.F90',
   'Utilities' / 'Matrix' / 'PetscMatrix.F90',
   'Solution' / 'PETSc' / 'PetscSolver.F90',
-  'Solution' / 'PETSc' / 'PetscConvergence.F90'
+  'Solution' / 'PETSc' / 'PetscConvergence.F90',
+  'Solution' / 'PETSc' / 'PetscImsPreconditioner.F90'
 )
 
 modflow_mpi_sources = files(
diff --git a/src/mf6core.f90 b/src/mf6core.f90
index f173596e33f..814cfe1857d 100644
--- a/src/mf6core.f90
+++ b/src/mf6core.f90
@@ -130,6 +130,8 @@ subroutine Mf6Finalize()
     use ListsModule, only: lists_da
     use SimulationCreateModule, only: simulation_da
     use TdisModule, only: tdis_da
+    use IdmLoadModule, only: idm_da
+    use SimVariablesModule, only: iout
     ! -- local variables
     integer(I4B) :: im
     integer(I4B) :: ic
@@ -141,6 +143,7 @@ subroutine Mf6Finalize()
     class(BaseExchangeType), pointer :: ep => null()
     class(SpatialModelConnectionType), pointer :: mc => null()
     !
+    !
     ! -- FINAL PROCESSING (FP)
     ! -- Final processing for each model
     do im = 1, basemodellist%Count()
@@ -198,6 +201,8 @@ subroutine Mf6Finalize()
       call sgp%sgp_da()
       deallocate (sgp)
     end do
+    !
+    call idm_da(iout)
     call simulation_da()
     call lists_da()
     !
@@ -229,8 +234,8 @@ end subroutine print_info
   subroutine create_lstfile()
     use ConstantsModule, only: LINELENGTH
     use SimVariablesModule, only: proc_id, nr_procs, simlstfile, iout
-    use InputOutputModule, only: getunit, openfile
-    use GenericUtilitiesModule, only: sim_message
+    use InputOutputModule, only: getunit, openfile, append_processor_id
+    use MessageModule, only: write_message
     use VersionModule, only: write_listfile_header
     character(len=LINELENGTH) :: line
     !
@@ -238,7 +243,7 @@ subroutine create_lstfile()
     iout = getunit()
     !
     if (nr_procs > 1) then
-      write (simlstfile, '(a,i0,a)') 'mfsim.p', proc_id, '.lst'
+      call append_processor_id(simlstfile, proc_id)
     end if
     !
     call openfile(iout, 0, simlstfile, 'LIST', filstat_opt='REPLACE')
@@ -247,7 +252,7 @@ subroutine create_lstfile()
     write (line, '(2(1x,A))') 'Writing simulation list file:', &
       trim(adjustl(simlstfile))
     !
-    call sim_message(line)
+    call write_message(line)
     call write_listfile_header(iout)
     !
     ! -- return
@@ -263,7 +268,7 @@ subroutine static_input_load()
     ! -- modules
     use ConstantsModule, only: LENMEMPATH
     use SimVariablesModule, only: iout
-    use IdmSimulationModule, only: simnam_load, load_models
+    use IdmLoadModule, only: simnam_load, load_models, load_exchanges
     use MemoryHelperModule, only: create_mem_path
     use MemoryManagerModule, only: mem_setptr, mem_allocate
     use SimVariablesModule, only: idm_context, iparamlog
@@ -285,9 +290,13 @@ subroutine static_input_load()
     ! -- initialize mask
     call create_load_mask(model_loadmask)
     !
-    ! -- load selected models
+    ! -- load in scope models
     call load_models(model_loadmask, iout)
     !
+    ! -- load in scope exchanges
+    call load_exchanges(model_loadmask, iout)
+    !
+    ! -- cleanup
     deallocate (model_loadmask)
     !
     ! -- return
@@ -302,6 +311,8 @@ end subroutine static_input_load
     !!
   !<
   subroutine simulation_df()
+    ! -- modules
+    use IdmLoadModule, only: idm_df
     ! -- local variables
     integer(I4B) :: im
     integer(I4B) :: ic
@@ -357,6 +368,9 @@ subroutine simulation_df()
       call sp%sln_df()
     end do
 
+    ! idm df
+    call idm_df()
+
   end subroutine simulation_df
 
   !> @brief Simulation allocate and read
@@ -423,9 +437,12 @@ end subroutine simulation_ar
   subroutine connections_cr()
     use ConnectionBuilderModule
     use SimVariablesModule, only: iout
+    use VersionModule, only: IDEVELOPMODE
     integer(I4B) :: isol
     type(ConnectionBuilderType) :: connectionBuilder
     class(BaseSolutionType), pointer :: sol => null()
+    integer(I4B) :: status
+    character(len=16) :: envvar
 
     write (iout, '(/a)') 'PROCESSING MODEL CONNECTIONS'
 
@@ -435,6 +452,15 @@ subroutine connections_cr()
       return
     end if
 
+    if (IDEVELOPMODE == 1) then
+      call get_environment_variable('DEV_ALWAYS_USE_IFMOD', &
+                                    value=envvar, status=status)
+      if (status == 0 .and. envvar == '1') then
+        connectionBuilder%dev_always_ifmod = .true.
+        write (iout, '(/a)') "Development option: forcing interface model"
+      end if
+    end if
+
     do isol = 1, basesolutionlist%Count()
       sol => GetBaseSolutionFromList(basesolutionlist, isol)
       call connectionBuilder%processSolution(sol)
@@ -468,6 +494,7 @@ subroutine Mf6PrepareTimestep()
     use BaseSolutionModule, only: BaseSolutionType, GetBaseSolutionFromList
     use SimModule, only: converge_reset
     use SimVariablesModule, only: isim_mode
+    use IdmLoadModule, only: idm_rp
     ! -- local variables
     class(BaseModelType), pointer :: mp => null()
     class(BaseExchangeType), pointer :: ep => null()
@@ -498,6 +525,9 @@ subroutine Mf6PrepareTimestep()
       line = trim(line)//'normal"'
     end select
 
+    ! -- load dynamic input
+    call idm_rp()
+
     ! -- Read and prepare each model
     do im = 1, basemodellist%Count()
       mp => GetBaseModelFromList(basemodellist, im)
@@ -505,6 +535,9 @@ subroutine Mf6PrepareTimestep()
       call mp%model_rp()
     end do
     !
+    ! -- Synchronize
+    call run_ctrl%at_stage(STG_BFR_EXG_RP)
+    !
     ! -- Read and prepare each exchange
     do ie = 1, baseexchangelist%Count()
       ep => GetBaseExchangeFromList(baseexchangelist, ie)
@@ -517,6 +550,9 @@ subroutine Mf6PrepareTimestep()
       call mc%exg_rp()
     end do
     !
+    ! -- Synchronize
+    call run_ctrl%at_stage(STG_AFT_CON_RP)
+    !
     ! -- reset simulation convergence flag
     call converge_reset()
     !
@@ -563,6 +599,7 @@ subroutine Mf6DoTimestep()
     use ListsModule, only: solutiongrouplist
     use SimVariablesModule, only: iFailedStepRetry
     use SolutionGroupModule, only: SolutionGroupType, GetSolutionGroupFromList
+    use IdmLoadModule, only: idm_ad
     ! -- local variables
     class(SolutionGroupType), pointer :: sgp => null()
     integer(I4B) :: isg
@@ -576,6 +613,9 @@ subroutine Mf6DoTimestep()
     iFailedStepRetry = 0
     retryloop: do
 
+      ! -- idm advance
+      call idm_ad()
+
       do isg = 1, solutiongrouplist%Count()
         sgp => GetSolutionGroupFromList(solutiongrouplist, isg)
         call sgp%sgp_ca()
diff --git a/src/simnamidm.f90 b/src/simnamidm.f90
index 86c6f058f37..f2a53f30a12 100644
--- a/src/simnamidm.f90
+++ b/src/simnamidm.f90
@@ -1,5 +1,6 @@
 ! ** Do Not Modify! MODFLOW 6 system generated file. **
 module SimNamInputModule
+  use ConstantsModule, only: LENVARNAME
   use InputDefinitionModule, only: InputParamDefinitionType, &
                                    InputBlockDefinitionType
   private
@@ -44,7 +45,8 @@ module SimNamInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -60,7 +62,8 @@ module SimNamInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -76,7 +79,8 @@ module SimNamInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -92,7 +96,8 @@ module SimNamInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -108,7 +113,8 @@ module SimNamInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -124,7 +130,8 @@ module SimNamInputModule
     .true., & ! required
     .false., & ! multi-record
     .true., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -140,7 +147,8 @@ module SimNamInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -156,7 +164,8 @@ module SimNamInputModule
     .true., & ! required
     .true., & ! multi-record
     .true., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -172,7 +181,8 @@ module SimNamInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -188,7 +198,8 @@ module SimNamInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -204,7 +215,8 @@ module SimNamInputModule
     .true., & ! required
     .true., & ! multi-record
     .true., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -220,7 +232,8 @@ module SimNamInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -236,7 +249,8 @@ module SimNamInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -252,7 +266,8 @@ module SimNamInputModule
     .false., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -268,7 +283,8 @@ module SimNamInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -284,7 +300,8 @@ module SimNamInputModule
     .true., & ! required
     .true., & ! multi-record
     .true., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -300,7 +317,8 @@ module SimNamInputModule
     .true., & ! required
     .true., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -338,7 +356,8 @@ module SimNamInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -354,7 +373,8 @@ module SimNamInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
@@ -370,7 +390,8 @@ module SimNamInputModule
     .true., & ! required
     .false., & ! multi-record
     .false., & ! preserve case
-    .false. & ! layered
+    .false., & ! layered
+    .false. & ! timeseries
     )
 
   type(InputParamDefinitionType), parameter :: &
diff --git a/srcbmi/mf6bmiUtil.f90 b/srcbmi/mf6bmiUtil.f90
index 4a5f1d1945e..f586ed6f79e 100644
--- a/srcbmi/mf6bmiUtil.f90
+++ b/srcbmi/mf6bmiUtil.f90
@@ -8,7 +8,7 @@ module mf6bmiUtil
                              LENMODELNAME, LINELENGTH, LENMEMTYPE, &
                              LENMEMADDRESS, LENCOMPONENTNAME
   use KindModule, only: DP, I4B, LGP
-  use GenericUtilitiesModule, only: sim_message
+  use MessageModule, only: write_message
   use SimVariablesModule, only: istdout
   use MemoryHelperModule, only: split_mem_address, split_mem_path
   implicit none
@@ -210,7 +210,7 @@ function get_model_name(grid_id) result(model_name)
     end do
 
     write (error_msg, '(a,i0)') 'BMI error: no model for grid id ', grid_id
-    call sim_message(error_msg, iunit=istdout, skipbefore=1, skipafter=1)
+    call write_message(error_msg, iunit=istdout, skipbefore=1, skipafter=1)
   end function get_model_name
 
   !> @brief Get the solution object for this index
diff --git a/utils/idmloader/IDM.md b/utils/idmloader/IDM.md
index 37ff976aa77..4b2d07c5ac4 100644
--- a/utils/idmloader/IDM.md
+++ b/utils/idmloader/IDM.md
@@ -1,111 +1,45 @@
-# MODFLOW 6 Input Data Model developer resource
-
+# MODFLOW 6 Input Data Model
 MODFLOW 6 reads simulation input from text and binary input files.  Traditionally, each model package has been responsible for reading its own input.  Although there are low-level utilities for reading arrays, and parsing input blocks, these utilities are called from dedicated read routines for each package.  To support new types of input, such as from NetCDF files or through the Application Programming Interface, a new effort is underway to implement a comprehensive Input Data Model (IDM) for MODFLOW 6.  Implementation of an Output Data Model may follow this effort.
 
-This document intends to describe, from a development perspective, the MODFLOW 6 IDM, and provide guidance for how to work with it. As the IDM is an active area of development this document should be expected to change frequently and will be updated to track with current state.
-
-* [Overview](#overview)
-* [Terminology](#terminology)
-* [Package Update Process](#package-update-process)
+- [Overview](#overview)
+- [Framework](#framework)
+- [Design](#design)
+- [Integration](#integration)
 
 ## Overview
-The MODFLOW 6 IDM is intended to provide a common entry point for simulation input data.  The approach is to read the input data first into memory and store the input data in the "input context."  Reading the simulation input into memory is performed by IDM load routines.  Model packages are then refactored so that they obtain their required information from the input context, rather than directly from the input files.  We refer to the process as "sourcing."  A model package "sources" its input from the input context.  The advantage here is that other readers can be implemented to load information into the input context, and then the model packages should work without modification.   This approach is built upon the MODFLOW 6 memory management infrastructure to define variable access paths that are scoped to a particular component/subcomponent. Input variables themselves are ultimately described by MODFLOW 6 definition (dfn) files.
+The MODFLOW 6 IDP (Input Data Processor) is a subsystem meant to generically read and store simulation input data from more than one type of input source.  It is built upon existing MODFLOW 6 capabilities, specifically input parameter descriptions currently stored in \*.dfn (definition) files, and the Memory Manager.  The parameter descriptions provide IDP with input block and parameter attributes needed to create memory and store input data.  The Memory Manager provides a globally accessible way to create, update, access and remove input (and other) data.  Existing components that read a traditional ASCII input file can be updated to source their input from the Memory Manager.  This type of update is a significant step towards supporting sources of input data other than the traditional ASCII files. 
 
-The MODFLOW 6 IDM is intended to decouple a simulation run from any particular, supported source of input that a user might construct. Currently,  MODFLOW 6 packages read input directly from proprietary MODFLOW-specific input files as required during a simulation run. The new design assigns responsibility for reading and loading data from the files to IDM proper, which builds the input context from the supported user input source (currently, MODFLOW 6 input files). Simulation components then access (or source) the input context to retrieve relevant input data.
+## Framework
+MODFLOW 6 \*.dfn files are used pre-compile time to generate fortran source files containing a subset of the parameter and block attribute information necessary to process input for the simulation. A single definition file is converted into one fortran source file that defines the component parameters and blocks and organizes them into lists.  This conversion from defintion file to fortran source file is currently managed by the [dfn2f90.py](scripts/dfn2f90.py) script.  This script also creates framework fortran source files with routines for generically accessing package definitions by component.  A package or other component intended to be updated and integrated with IDM must be added to the dfn2f90.py script.  This process is described below.
 
-## Terminology
-### Definition File (.dfn suffix)
-MODFLOW 6 dfn file formats are described in the [dfn readme.md](../../doc/mf6io/mf6ivar/readme.md). These definition files describe MODFLOW 6 input files and parameters.  They are used to generate the documentation in mf6io.pdf.  They are also used to auto-generate the FloPy classes for MODFLOW 6. Definition files are also read as input to the dfn2f90.py script, which is a new utility developed as part of this IDM effort.  This script generates Fortran source code that describes MODFLOW 6 input.  The Fortran source code generated by dfn2f90.py defines the input parameters and input file structure, and is used by IDM to load simulation input.
-### input definition
-The Fortran version of the Input definitions are generated from MODFLOW 6 dfn files and describe input parameter or blocks:
+## Design
+Input data stored in the Memory Manager use the special identifier ```__INPUT__``` as a prefix to a memory path.  MODFLOW 6 refers to memory path prefixes such as these as a "context" and as such the collection of input data stored in the Memory Manager is referred to as the "input context".
 
-```fortran
-type(InputParamDefinitionType), parameter :: &
-  gwtdsp_opt_xt3d_off = InputParamDefinitionType &
-  ( &
-  'GWT', & ! component
-  'DSP', & ! subcomponent
-  'OPTIONS', & ! block
-  'XT3D_OFF', & ! tag name
-  'XT3D_OFF', & ! fortran variable
-  'KEYWORD', & ! type
-  '', & ! shape
-  .false., & ! required
-  .false., & ! multi-record
-  .false., & ! preserve case
-  .false. & ! layered
-  )
-```    
+IDM defines and implements loaders as objects to read input from some supported source and to allocate and store that input in a source independent way for the package or component.  Variations across sources are managed by the loaders.  Input retrieved by simulation packages is stuctured such that the source is not apparent or relevant to the package.
 
-These Fortran definitions are used by IDM input handlers to interpret user input and load input data into the input context.
+IDM distinguishes between static and dynamic loader objects.  Static loader objects load all pre-period input before any simulation objects are created and prepare for dynamic (stress period) data loads by creating the dynamic loader when relevant.  Static and dynamic loaders are defined per supported source by extending base types defined in [InputLoadType.f90](../../src/Utilities/Idm/InputLoadType.f90).  Top level IDM context ([IdmLoad.f90](../../src/Utilities/Idm/IdmLoad.f90)) maintains pointers to loader base types and invoke the common deferred interfaces load() (static) and rp() (dynamic) for each component.  Each source can introduce as much complexity as needed to support variations in input by introducing source specific loader types.  For example, there are currently distinct loaders for dynamic ASCII list based and array-based inputs.  These sub-loaders are allocated and managed within the context of a given source (e.g. ASCII).
 
-A related set of input definitions are contained in a Fortran file that is named from the related package file, e.g. [gwf3npf8idm.f90](../../src/Model/GroundWaterFlow/gwf3npf8idm.f90) contains input definitions relevant to [gwf3npf8.f90](../../src/Model/GroundWaterFlow/gwf3npf8.f90). A Fortran input definition file is organized into 3 lists, a parameter (input variable) list, an aggregate (similar to a numpy recarray) list, and a block list.  The Fortran input definitions also contain the definition for a found type object that can be used within packages to track what input variable paths were loaded into the input context by the IDM load routine:
+## Integration
+A simulation component (package, etc) can be integrated with IDM by following these steps:
+- Create dfn file
+- Add component to dfn2f90.py and run script
+- Update MODFLOW 6 build scripts (e.g. meson / msvs)
+- Use common intefaces to source input from input context
+
+The dfn file is already a requirement for MODFLOW 6 package integration and so is not an IDM specific requirement.  The dfn2f90.py update should be straightforward and currently amounts to specifying the input path to the package dfn file and an output path for the generated package \*idm.f90 file.  To run the script:
 
-```fortran
-type GwtDspParamFoundType
-  logical :: opt_xt3d_off = .false.
-  logical :: opt_xt3d_rhs = .false.
-  logical :: grid_diffc = .false.
-  logical :: grid_alh = .false.
-  logical :: grid_alv = .false.
-  logical :: grid_ath1 = .false.
-  logical :: grid_ath2 = .false.
-  logical :: grid_atv = .false.
-end type GwtDspParamFoundType`
-```
-## Package Update process
-###	Update [dfn2f90.py](scripts/dfn2f90.py)
-Add a new dfns entry in main, designating paths and names for the input dfn and output f90 files.
-### Run the dfn2f90.py script
 ```shell
 cd utils/idmloader/scripts
 python dfn2f90.py
 ```
-This will create the new IDM Fortran definition file at the location designated.  This will also automatically update IDM selector modules so that the newly generated definitions can be used.  If a new component (e.g. a new model) has been introduced, a new selector file will be generated in the src/Utitilites/Idm/selector directory.
-### Update [meson.build](../../src/meson.build) and [mf6core.vfproj](../../msvs/mf6core.vfproj)
-Add any newly generated fortran files to relevant build scripts to compile new definitions and definition select routines into MODFLOW 6 binaries.
-
-Note:  To simplify the update process, all necessary internal modifications are performed when dfn2f90.py is run.  Compiling with these changes immediately updates IDM to treat any newly added package as integrated.  This may not be the case if, for example, model package code has not been updated to source input from the input context.  GWF and GWT model code is fully integrated with IDM and as such either a valid unit number (for packages that are not IDM integrated) or a valid mempath (for packages that are IDM integrated) is passed into a package but not both.  Once a new fortran idm definition file has been compiled in, a valid unit number will no longer be provided to the package and parser operations will fail if attempted.
-### Update the package file
-#### Source package input data 
-To convert a package to use the new IDM approach, the read routine for the package must be replaced by a sourcing routine that accesses data from the input context.  The implementation of the source routine is dependent on the data itself but a common pattern is to use the MemoryManagerExtModule `mem_set_value()` interface to copy data from the input context to package paths.  A parameter found type, in the generated IDM definition file, should be used to pass a corresponding logical to `mem_set_value()`, which sets the logical to True if the input path was found and data was copied.  When sourcing has been completed, the found type parameter logicals can be checked to determine what other actions need to be taken in response to both found or not found input data.
-
-```fortran
-character(len=LENMEMPATH) :: idmMemoryPath
-type(GwtDspParamFoundType) :: found
-! ------------------------------------------------------------------------------
-!
-! -- set memory path
-idmMemoryPath = create_mem_path(this%name_model, 'DSP', idm_context)
-!
-! -- update defaults with idm sourced values
-call mem_set_value(this%ixt3doff, 'XT3D_OFF', idmMemoryPath, found%opt_xt3d_off)
-call mem_set_value(this%ixt3drhs, 'XT3D_RHS', idmMemoryPath, found%opt_xt3d_rhs)
-!
-! -- set xt3d state flag
-if (found%opt_xt3d_off) this%ixt3d = 0
-if (found%opt_xt3d_rhs) this%ixt3d = 2
-```
+Running this command will generate a new definition file for the package and update the IDM selector framework.  If the package also introduces a new model then a new selector framework file will also be created.  Update the MODFLOW 6 build system (meson and msvs) files with any newly generated files.
 
-#### Deallocate package input paths
-In deallocate, add a call to MemoryManagerExtModule `memorylist_remove()` for the package.  This call will search the subcomponent input path and deallocate all memory that was allocated as part of the load process.
+Once these files have been added to the build the package can be updated to source it's input from the input context.  In general, static input data is copied from the input context to the package (or "model") context by using the ```mem_set_value()``` interface:
 
-```fortran
-! -- Deallocate input memory
-call memorylist_remove(this%name_model, 'DSP', idm_context)
-```
-
-## Adding params to packages already using IDM
-
-Once a model package has been modified to use the IDM approach, adding a new package option or block requires two steps.  The steps are as follows. 
-
-### Update appropriate dfn file with new param(s)
-### Run the dfn2f90.py script
 ```shell
-cd utils/idmloader/scripts
-python dfn2f90.py
+call mem_set_value(this%xorigin, 'XORIGIN', this%input_mempath, found%xorigin)
 ```
 
-This will update the existing idm package f90 file to add the new parameter definition.  Compile to update the binaries.
-#### Source package input data
-Update the package source routine for the relevant block to copy the data from the input path to the package path. Take any necessary action depending on whether the data was found or not found. 
+The found instance is a convenience type generated by dfn2f90.py and should be complete and ready to use from the \*idm.f90 package module.  The inteface updates the data pointer (```this%xorigin``` in the example) only if the relevant data was provided as input and will set the logical ```found%xorigin``` to TRUE when this is the case.
+
+Dynamic data can also be copied between contexts by using the ```mem_set_value()``` interface or it can be accessed directly by setting a pointer to it.  In most cases, dynamic input memory is not reallocated during it's lifetime and such a pointer is valid for the duration of the simulation.  See CHD package code for an example (e.g. "HEAD")
diff --git a/utils/idmloader/README.md b/utils/idmloader/README.md
deleted file mode 100644
index 300d55e9811..00000000000
--- a/utils/idmloader/README.md
+++ /dev/null
@@ -1,3 +0,0 @@
-# idmloader
-
-This is a placeholder for the idmloader utility, a standalone tool that populates input memory paths from a supported input source.
diff --git a/utils/idmloader/scripts/dfn2f90.py b/utils/idmloader/scripts/dfn2f90.py
index 6f59df4b38b..5b5a0c58c99 100644
--- a/utils/idmloader/scripts/dfn2f90.py
+++ b/utils/idmloader/scripts/dfn2f90.py
@@ -1,11 +1,11 @@
-import os
 import sys
-import json
 from pathlib import Path
-from enum import Enum
 
 MF6_LENVARNAME = 16
 F90_LINELEN = 82
+PROJ_ROOT = Path(__file__).parents[3]
+DFN_PATH = PROJ_ROOT / "doc" / "mf6io" / "mf6ivar" / "dfn"
+SRC_PATH = PROJ_ROOT / "src"
 
 
 class Dfn2F90:
@@ -46,7 +46,6 @@ def add_dfn_entry(self, dfn_d=None):
 
     def write_f90(self, ofspec=None):
         with open(ofspec, "w") as f:
-
             # file header
             f.write(self._source_file_header(self.component, self.subcomponent))
 
@@ -138,7 +137,6 @@ def _set_var_d(self):
         vd = {}
 
         for line in lines:
-
             # skip blank lines
             if len(line.strip()) == 0:
                 if len(vd) > 0:
@@ -256,7 +254,8 @@ def _set_param_strs(self):
             self._param_str += "    .false., & ! required\n"
             self._param_str += "    .false., & ! multi-record\n"
             self._param_str += "    .false., & ! preserve case\n"
-            self._param_str += "    .false. & ! layered\n"
+            self._param_str += "    .false., & ! layered\n"
+            self._param_str += "    .false. & ! timeseries\n"
             self._param_str += "    ), &\n"
 
         if not self._aggregate_str:
@@ -272,7 +271,8 @@ def _set_param_strs(self):
             self._aggregate_str += "    .false., & ! required\n"
             self._aggregate_str += "    .false., & ! multi-record\n"
             self._aggregate_str += "    .false., & ! preserve case\n"
-            self._aggregate_str += "    .false. & ! layered\n"
+            self._aggregate_str += "    .false., & ! layered\n"
+            self._aggregate_str += "    .false. & ! timeseries\n"
             self._aggregate_str += "    ), &\n"
 
         if not self._block_str:
@@ -301,7 +301,6 @@ def _set_blk_param_strs(self, blockname, component, subcomponent):
             r = ".false."
 
         for k in self._var_d:
-
             varname, bname = k
             if bname != blockname:
                 continue
@@ -333,12 +332,23 @@ def _set_blk_param_strs(self, blockname, component, subcomponent):
 
             shape = ""
             shapelist = []
+            # workaround for Flopy shape issue with exg dfns:
+            if c.upper() == "EXG":
+                if vn == "CELLIDM1" or vn == "CELLIDM2":
+                    v["shape"] = "(ncelldim)"
             if "shape" in v:
                 shape = v["shape"]
                 shape = shape.replace("(", "")
                 shape = shape.replace(")", "")
                 shape = shape.replace(",", "")
                 shape = shape.upper()
+                if shape == "NCOL*NROW; NCPL":
+                    # grid array input syntax
+                    if mf6vn == "AUXVAR":
+                        # for grid, set AUX as DOUBLE2D
+                        shape = "NAUX NCPL"
+                    else:
+                        shape = "NCPL"
                 shapelist = shape.strip().split()
             ndim = len(shapelist)
 
@@ -375,6 +385,13 @@ def _set_blk_param_strs(self, blockname, component, subcomponent):
                 else:
                     layered = ".false."
 
+            timeseries = ".false."
+            if "time_series" in v:
+                if v["time_series"] == "true":
+                    timeseries = ".true."
+                else:
+                    timeseries = ".false."
+
             if inrec == ".false.":
                 required_l.append(r)
             tuple_list = [
@@ -389,6 +406,7 @@ def _set_blk_param_strs(self, blockname, component, subcomponent):
                 (inrec, "multi-record"),
                 (preserve_case, "preserve case"),
                 (layered, "layered"),
+                (timeseries, "timeseries"),
             ]
 
             if aggregate_t:
@@ -443,6 +461,7 @@ def _source_file_header(self, component, subcomponent):
         s = (
             f"! ** Do Not Modify! MODFLOW 6 system generated file. **\n"
             f"module {component.title()}{subcomponent.title()}InputModule\n"
+            f"  use ConstantsModule, only: LENVARNAME\n"
             f"  use InputDefinitionModule, only: InputParamDefinitionType, &\n"
             f"                                   InputBlockDefinitionType\n"
             f"  private\n"
@@ -505,6 +524,7 @@ class IdmDfnSelector:
     def __init__(
         self,
         dfn_d: dict = None,
+        varnames: list = None,
     ):
         """IdmDfnSelector init"""
 
@@ -515,7 +535,7 @@ def write(self):
         self._write_master()
 
     def _write_master(self):
-        ofspec = f"../../../src/Utilities/Idm/selector/IdmDfnSelector.f90"
+        ofspec = SRC_PATH / "Utilities" / "Idm" / "selector" / "IdmDfnSelector.f90"
         with open(ofspec, "w") as fh:
             self._write_master_decl(fh)
             self._write_master_defn(fh, defn="param", dtype="param")
@@ -523,12 +543,17 @@ def _write_master(self):
             self._write_master_defn(fh, defn="block", dtype="block")
             self._write_master_multi(fh)
             self._write_master_integration(fh)
+            self._write_master_component(fh)
             fh.write(f"end module IdmDfnSelectorModule\n")
 
     def _write_selectors(self):
         for c in self._d:
             ofspec = (
-                f"../../../src/Utilities/Idm/selector/Idm{c.title()}DfnSelector.f90"
+                SRC_PATH
+                / "Utilities"
+                / "Idm"
+                / "selector"
+                / f"Idm{c.title()}DfnSelector.f90"
             )
             with open(ofspec, "w") as fh:
                 self._write_selector_decl(fh, component=c, sc_list=self._d[c])
@@ -554,6 +579,7 @@ def _write_selector_decl(self, fh=None, component=None, sc_list=None):
         s = (
             f"! ** Do Not Modify! MODFLOW 6 system generated file. **\n"
             f"module Idm{c.title()}DfnSelectorModule\n\n"
+            f"  use ConstantsModule, only: LENVARNAME\n"
             f"  use SimModule, only: store_error\n"
             f"  use InputDefinitionModule, only: InputParamDefinitionType, &\n"
             f"                                   InputBlockDefinitionType\n"
@@ -563,16 +589,7 @@ def _write_selector_decl(self, fh=None, component=None, sc_list=None):
             len_sc = len(sc)
             spacer = space * (len_c + len_sc)
 
-            s += (
-                f"  use {c.title()}{sc.title()}InputModule, only: "
-                f"{c.lower()}_{sc.lower()}_param_definitions, &"
-                f"\n                         {spacer}"
-                f"{c.lower()}_{sc.lower()}_aggregate_definitions, &"
-                f"\n                         {spacer}"
-                f"{c.lower()}_{sc.lower()}_block_definitions, &"
-                f"\n                         {spacer}"
-                f"{c.lower()}_{sc.lower()}_multi_package\n"
-            )
+            s += f"  use {c.title()}{sc.title()}InputModule\n"
 
         s += (
             f"\n  implicit none\n"
@@ -582,8 +599,8 @@ def _write_selector_decl(self, fh=None, component=None, sc_list=None):
             f"  public :: {c.lower()}_block_definitions\n"
             f"  public :: {c.lower()}_idm_multi_package\n"
             f"  public :: {c.lower()}_idm_integrated\n\n"
-            f"contains\n\n"
         )
+        s += f"contains\n\n"
 
         fh.write(s)
 
@@ -704,6 +721,7 @@ def _write_master_decl(self, fh=None):
         s = (
             f"! ** Do Not Modify! MODFLOW 6 system generated file. **\n"
             f"module IdmDfnSelectorModule\n\n"
+            f"  use ConstantsModule, only: LENVARNAME\n"
             f"  use SimModule, only: store_error\n"
             f"  use InputDefinitionModule, only: InputParamDefinitionType, &\n"
             f"                                   InputBlockDefinitionType\n"
@@ -712,18 +730,7 @@ def _write_master_decl(self, fh=None):
         for c in self._d:
             len_c = len(c)
             spacer = space * (len_c)
-            s += (
-                f"  use Idm{c.title()}DfnSelectorModule, only: "
-                f"{c.lower()}_param_definitions, &"
-                f"\n                                  {spacer}"
-                f"{c.lower()}_aggregate_definitions, &"
-                f"\n                                  {spacer}"
-                f"{c.lower()}_block_definitions, &"
-                f"\n                                  {spacer}"
-                f"{c.lower()}_idm_multi_package, &"
-                f"\n                                  {spacer}"
-                f"{c.lower()}_idm_integrated\n"
-            )
+            s += f"  use Idm{c.title()}DfnSelectorModule\n"
 
         s += (
             f"\n  implicit none\n"
@@ -732,7 +739,8 @@ def _write_master_decl(self, fh=None):
             f"  public :: aggregate_definitions\n"
             f"  public :: block_definitions\n"
             f"  public :: idm_multi_package\n"
-            f"  public :: idm_integrated\n\n"
+            f"  public :: idm_integrated\n"
+            f"  public :: idm_component\n\n"
             f"contains\n\n"
         )
 
@@ -823,55 +831,136 @@ def _write_master_integration(self, fh=None):
 
         fh.write(s)
 
+    def _write_master_component(self, fh=None):
+        s = (
+            f"  function idm_component(component) "
+            f"result(integrated)\n"
+            f"    character(len=*), intent(in) :: component\n"
+            f"    logical :: integrated\n"
+            f"    integrated = .false.\n"
+            f"    select case (component)\n"
+        )
+
+        for c in dfn_d:
+            s += f"    case ('{c}')\n" f"      integrated = .true.\n"
+
+        s += (
+            f"    case default\n"
+            f"    end select\n"
+            f"    return\n"
+            f"  end function idm_component\n\n"
+        )
+
+        fh.write(s)
+
 
 if __name__ == "__main__":
-
     dfns = [
         # ** Add a new dfn parameter set to MODFLOW 6 by adding a new entry to this list **
         # [relative path of input dnf, relative path of output f90 definition file]
         [
-            Path("../../../doc/mf6io/mf6ivar/dfn", "gwf-dis.dfn"),
-            Path("../../../src/Model/GroundWaterFlow", "gwf3dis8idm.f90"),
+            DFN_PATH / "gwf-chd.dfn",
+            SRC_PATH / "Model" / "GroundWaterFlow" / "gwf3chd8idm.f90",
+        ],
+        [
+            DFN_PATH / "gwf-dis.dfn",
+            SRC_PATH / "Model" / "GroundWaterFlow" / "gwf3dis8idm.f90",
+        ],
+        [
+            DFN_PATH / "gwf-disu.dfn",
+            SRC_PATH / "Model" / "GroundWaterFlow" / "gwf3disu8idm.f90",
+        ],
+        [
+            DFN_PATH / "gwf-disv.dfn",
+            SRC_PATH / "Model" / "GroundWaterFlow" / "gwf3disv8idm.f90",
+        ],
+        [
+            DFN_PATH / "gwf-drn.dfn",
+            SRC_PATH / "Model" / "GroundWaterFlow" / "gwf3drn8idm.f90",
+        ],
+        [
+            DFN_PATH / "gwf-evt.dfn",
+            SRC_PATH / "Model" / "GroundWaterFlow" / "gwf3evt8idm.f90",
+        ],
+        [
+            DFN_PATH / "gwf-evta.dfn",
+            SRC_PATH / "Model" / "GroundWaterFlow" / "gwf3evta8idm.f90",
+        ],
+        [
+            DFN_PATH / "gwf-ghb.dfn",
+            SRC_PATH / "Model" / "GroundWaterFlow" / "gwf3ghb8idm.f90",
+        ],
+        [
+            DFN_PATH / "gwf-ic.dfn",
+            SRC_PATH / "Model" / "GroundWaterFlow" / "gwf3ic8idm.f90",
+        ],
+        [
+            DFN_PATH / "gwf-npf.dfn",
+            SRC_PATH / "Model" / "GroundWaterFlow" / "gwf3npf8idm.f90",
+        ],
+        [
+            DFN_PATH / "gwf-rch.dfn",
+            SRC_PATH / "Model" / "GroundWaterFlow" / "gwf3rch8idm.f90",
+        ],
+        [
+            DFN_PATH / "gwf-rcha.dfn",
+            SRC_PATH / "Model" / "GroundWaterFlow" / "gwf3rcha8idm.f90",
+        ],
+        [
+            DFN_PATH / "gwf-riv.dfn",
+            SRC_PATH / "Model" / "GroundWaterFlow" / "gwf3riv8idm.f90",
+        ],
+        [
+            DFN_PATH / "gwf-wel.dfn",
+            SRC_PATH / "Model" / "GroundWaterFlow" / "gwf3wel8idm.f90",
+        ],
+        [
+            DFN_PATH / "gwt-dis.dfn",
+            SRC_PATH / "Model" / "GroundWaterTransport" / "gwt1dis1idm.f90",
+        ],
+        [
+            DFN_PATH / "gwt-disu.dfn",
+            SRC_PATH / "Model" / "GroundWaterTransport" / "gwt1disu1idm.f90",
         ],
         [
-            Path("../../../doc/mf6io/mf6ivar/dfn", "gwf-disu.dfn"),
-            Path("../../../src/Model/GroundWaterFlow", "gwf3disu8idm.f90"),
+            DFN_PATH / "gwt-disv.dfn",
+            SRC_PATH / "Model" / "GroundWaterTransport" / "gwt1disv1idm.f90",
         ],
         [
-            Path("../../../doc/mf6io/mf6ivar/dfn", "gwf-disv.dfn"),
-            Path("../../../src/Model/GroundWaterFlow", "gwf3disv8idm.f90"),
+            DFN_PATH / "gwt-dsp.dfn",
+            SRC_PATH / "Model" / "GroundWaterTransport" / "gwt1dsp1idm.f90",
         ],
         [
-            Path("../../../doc/mf6io/mf6ivar/dfn", "gwf-npf.dfn"),
-            Path("../../../src/Model/GroundWaterFlow", "gwf3npf8idm.f90"),
+            DFN_PATH / "gwt-cnc.dfn",
+            SRC_PATH / "Model" / "GroundWaterTransport" / "gwt1cnc1idm.f90",
         ],
         [
-            Path("../../../doc/mf6io/mf6ivar/dfn", "gwt-dis.dfn"),
-            Path("../../../src/Model/GroundWaterTransport", "gwt1dis1idm.f90"),
+            DFN_PATH / "gwt-ic.dfn",
+            SRC_PATH / "Model" / "GroundWaterTransport" / "gwt1ic1idm.f90",
         ],
         [
-            Path("../../../doc/mf6io/mf6ivar/dfn", "gwt-disu.dfn"),
-            Path("../../../src/Model/GroundWaterTransport", "gwt1disu1idm.f90"),
+            DFN_PATH / "gwf-nam.dfn",
+            SRC_PATH / "Model" / "GroundWaterFlow" / "gwf3idm.f90",
         ],
         [
-            Path("../../../doc/mf6io/mf6ivar/dfn", "gwt-disv.dfn"),
-            Path("../../../src/Model/GroundWaterTransport", "gwt1disv1idm.f90"),
+            DFN_PATH / "gwt-nam.dfn",
+            SRC_PATH / "Model" / "GroundWaterTransport" / "gwt1idm.f90",
         ],
         [
-            Path("../../../doc/mf6io/mf6ivar/dfn", "gwt-dsp.dfn"),
-            Path("../../../src/Model/GroundWaterTransport", "gwt1dsp1idm.f90"),
+            DFN_PATH / "exg-gwfgwf.dfn",
+            SRC_PATH / "Exchange" / "gwfgwfidm.f90",
         ],
         [
-            Path("../../../doc/mf6io/mf6ivar/dfn", "gwf-nam.dfn"),
-            Path("../../../src/Model/GroundWaterFlow", "gwf3idm.f90"),
+            DFN_PATH / "exg-gwfgwt.dfn",
+            SRC_PATH / "Exchange" / "gwfgwtidm.f90",
         ],
         [
-            Path("../../../doc/mf6io/mf6ivar/dfn", "gwt-nam.dfn"),
-            Path("../../../src/Model/GroundWaterTransport", "gwt1idm.f90"),
+            DFN_PATH / "exg-gwtgwt.dfn",
+            SRC_PATH / "Exchange" / "gwtgwtidm.f90",
         ],
         [
-            Path("../../../doc/mf6io/mf6ivar/dfn", "sim-nam.dfn"),
-            Path("../../../src", "simnamidm.f90"),
+            DFN_PATH / "sim-nam.dfn",
+            SRC_PATH / "simnamidm.f90",
         ],
     ]
 
diff --git a/utils/mf5to6/make/makedefaults b/utils/mf5to6/make/makedefaults
index fdc2fdb51cb..e7b3710e4ab 100644
--- a/utils/mf5to6/make/makedefaults
+++ b/utils/mf5to6/make/makedefaults
@@ -1,4 +1,4 @@
-# makedefaults created by pymake (version 1.2.7) for the 'mf5to6' executable.
+# makedefaults created by pymake (version 1.2.9.dev0) for the 'mf5to6' executable.
 
 # determine OS
 ifeq ($(OS), Windows_NT)
@@ -64,12 +64,9 @@ else
 		FFLAGS ?= -fbacktrace -ffpe-summary=overflow -ffpe-trap=overflow,zero,invalid $(OS_macro) -cpp
 	endif
 	ifeq ($(FC), $(filter $(FC), ifort mpiifort))
-		FFLAGS ?= -no-heap-arrays -fpe0 -traceback -fpp
+		FFLAGS ?= -no-heap-arrays -fpe0 -traceback -Qdiag-disable:7416 -Qdiag-disable:7025 -Qdiag-disable:5268 -fpp
 		MODSWITCH = -module $(MODDIR)
 	endif
-	ifeq ($(FC), $(filter $(FC), ftn))
-		FFLAGS ?= -h noheap_allocate
-	endif
 endif
 
 # set the ldflgs
@@ -84,9 +81,6 @@ else
 	ifeq ($(FC), $(filter $(FC), ifort mpiifort))
 		LDFLAGS ?= -lc
 	endif
-	ifeq ($(FC), $(filter $(FC), ftn))
-		LDFLAGS ?= -lc
-	endif
 endif
 
 # check for Windows error condition
diff --git a/utils/mf5to6/make/makefile b/utils/mf5to6/make/makefile
index d8eb7e6963d..ccf5741d638 100644
--- a/utils/mf5to6/make/makefile
+++ b/utils/mf5to6/make/makefile
@@ -1,14 +1,14 @@
-# makefile created by pymake (version 1.2.7) for the 'mf5to6' executable.
+# makefile created by pymake (version 1.2.9.dev0) for the 'mf5to6' executable.
 
 
 include ./makedefaults
 
 # Define the source file directories
 SOURCEDIR1=../src
-SOURCEDIR2=../src/NWT
-SOURCEDIR3=../src/LGR
-SOURCEDIR4=../src/Preproc
-SOURCEDIR5=../src/MF2005
+SOURCEDIR2=../src/LGR
+SOURCEDIR3=../src/Preproc
+SOURCEDIR4=../src/MF2005
+SOURCEDIR5=../src/NWT
 SOURCEDIR6=../../../src/Utilities/Memory
 SOURCEDIR7=../../../src/Utilities/TimeSeries
 SOURCEDIR8=../../../src/Utilities
@@ -28,30 +28,35 @@ ${SOURCEDIR8}
 OBJECTS = \
 $(OBJDIR)/kind.o \
 $(OBJDIR)/Constants.o \
+$(OBJDIR)/Global.o \
 $(OBJDIR)/SimVariables.o \
-$(OBJDIR)/genericutils.o \
+$(OBJDIR)/ArrayHandlers.o \
+$(OBJDIR)/Message.o \
 $(OBJDIR)/defmacro.o \
 $(OBJDIR)/compilerversion.o \
 $(OBJDIR)/version.o \
 $(OBJDIR)/OpenSpec.o \
-$(OBJDIR)/Global.o \
 $(OBJDIR)/GlobalVariables.o \
-$(OBJDIR)/ArrayHandlers.o \
 $(OBJDIR)/SimPHMF.o \
 $(OBJDIR)/InputOutput.o \
 $(OBJDIR)/TableTerm.o \
 $(OBJDIR)/Table.o \
 $(OBJDIR)/MemoryHelper.o \
 $(OBJDIR)/CharString.o \
+$(OBJDIR)/ErrorUtil.o \
 $(OBJDIR)/Memory.o \
 $(OBJDIR)/List.o \
 $(OBJDIR)/MemoryList.o \
+$(OBJDIR)/LongLineReader.o \
+$(OBJDIR)/DevFeature.o \
 $(OBJDIR)/Utilities.o \
 $(OBJDIR)/ConstantsPHMF.o \
 $(OBJDIR)/MemoryManager.o \
+$(OBJDIR)/GeomUtil.o \
 $(OBJDIR)/BlockParser.o \
 $(OBJDIR)/ArrayReadersMF5.o \
 $(OBJDIR)/precutls.o \
+$(OBJDIR)/MathUtil.o \
 $(OBJDIR)/GlobalVariablesPHMF.o \
 $(OBJDIR)/DiscretizationBasePHMF.o \
 $(OBJDIR)/File.o \
diff --git a/utils/mf5to6/msvs/mf5to6.vfproj b/utils/mf5to6/msvs/mf5to6.vfproj
index 0fdd1b971ce..10ff7233751 100644
--- a/utils/mf5to6/msvs/mf5to6.vfproj
+++ b/utils/mf5to6/msvs/mf5to6.vfproj
@@ -1,28 +1,32 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <VisualStudioProject ProjectCreator="Intel Fortran" Keyword="Console Application" Version="11.0" ProjectIdGuid="{EE5F8367-9220-45ED-9B0B-5942AF51229C}">
 	<Platforms>
-		<Platform Name="Win32"/></Platforms>
+		<Platform Name="Win32"/>
+	</Platforms>
 	<Configurations>
 		<Configuration Name="Debug|Win32" TargetName="$(ProjectName)d">
-				<Tool Name="VFFortranCompilerTool" SuppressStartupBanner="true" DebugInformationFormat="debugEnabled" Optimization="optimizeDisabled" HeapArrays="0" WarnUnusedVariables="true" WarnUncalled="true" WarnInterfaces="true" Traceback="true" NullPointerCheck="true" BoundsCheck="true" UninitializedVariablesCheck="true" StackFrameCheck="true" RuntimeLibrary="rtMultiThreadedDebug"/>
-				<Tool Name="VFLinkerTool" LinkIncremental="linkIncrementalNo" SuppressStartupBanner="true" GenerateDebugInformation="true" SubSystem="subSystemConsole"/>
-				<Tool Name="VFResourceCompilerTool"/>
-				<Tool Name="VFMidlTool" SuppressStartupBanner="true"/>
-				<Tool Name="VFCustomBuildTool"/>
-				<Tool Name="VFPreLinkEventTool"/>
-				<Tool Name="VFPreBuildEventTool"/>
-				<Tool Name="VFPostBuildEventTool" CommandLine="copy $(OutDir)\$(TargetName)$(TargetExt) ..\..\..\bin"/>
-				<Tool Name="VFManifestTool" SuppressStartupBanner="true"/></Configuration>
+			<Tool Name="VFFortranCompilerTool" SuppressStartupBanner="true" DebugInformationFormat="debugEnabled" Optimization="optimizeDisabled" HeapArrays="0" WarnUnusedVariables="true" WarnUncalled="true" WarnInterfaces="true" Traceback="true" NullPointerCheck="true" BoundsCheck="true" UninitializedVariablesCheck="true" StackFrameCheck="true" RuntimeLibrary="rtMultiThreadedDebug"/>
+			<Tool Name="VFLinkerTool" LinkIncremental="linkIncrementalNo" SuppressStartupBanner="true" GenerateDebugInformation="true" SubSystem="subSystemConsole"/>
+			<Tool Name="VFResourceCompilerTool"/>
+			<Tool Name="VFMidlTool" SuppressStartupBanner="true"/>
+			<Tool Name="VFCustomBuildTool"/>
+			<Tool Name="VFPreLinkEventTool"/>
+			<Tool Name="VFPreBuildEventTool"/>
+			<Tool Name="VFPostBuildEventTool" CommandLine="copy $(OutDir)\$(TargetName)$(TargetExt) ..\..\..\bin"/>
+			<Tool Name="VFManifestTool" SuppressStartupBanner="true"/>
+		</Configuration>
 		<Configuration Name="Release|Win32">
-				<Tool Name="VFFortranCompilerTool" SuppressStartupBanner="true" DebugInformationFormat="debugEnabled" HeapArrays="0" RuntimeLibrary="rtMultiThreadedDebug"/>
-				<Tool Name="VFLinkerTool" SuppressStartupBanner="true" GenerateDebugInformation="true" SubSystem="subSystemConsole"/>
-				<Tool Name="VFResourceCompilerTool"/>
-				<Tool Name="VFMidlTool" SuppressStartupBanner="true"/>
-				<Tool Name="VFCustomBuildTool"/>
-				<Tool Name="VFPreLinkEventTool"/>
-				<Tool Name="VFPreBuildEventTool"/>
-				<Tool Name="VFPostBuildEventTool" CommandLine="copy $(OutDir)\$(TargetName)$(TargetExt) ..\..\..\bin"/>
-				<Tool Name="VFManifestTool" SuppressStartupBanner="true"/></Configuration></Configurations>
+			<Tool Name="VFFortranCompilerTool" SuppressStartupBanner="true" DebugInformationFormat="debugEnabled" HeapArrays="0" RuntimeLibrary="rtMultiThreadedDebug"/>
+			<Tool Name="VFLinkerTool" SuppressStartupBanner="true" GenerateDebugInformation="true" SubSystem="subSystemConsole"/>
+			<Tool Name="VFResourceCompilerTool"/>
+			<Tool Name="VFMidlTool" SuppressStartupBanner="true"/>
+			<Tool Name="VFCustomBuildTool"/>
+			<Tool Name="VFPreLinkEventTool"/>
+			<Tool Name="VFPreBuildEventTool"/>
+			<Tool Name="VFPostBuildEventTool" CommandLine="copy $(OutDir)\$(TargetName)$(TargetExt) ..\..\..\bin"/>
+			<Tool Name="VFManifestTool" SuppressStartupBanner="true"/>
+		</Configuration>
+	</Configurations>
 	<Files>
 		<Filter Name="Header Files" Filter="fi;fd"/>
 		<Filter Name="Resource Files" Filter="rc;ico;cur;bmp;dlg;rc2;rct;bin;rgs;gif;jpg;jpeg;jpe"/>
@@ -93,12 +97,19 @@
 		<File RelativePath="..\..\..\src\Utilities\CharString.f90"/>
 		<File RelativePath="..\..\..\src\Utilities\compilerversion.F90">
 			<FileConfiguration Name="Debug|Win32">
-				<Tool Name="VFFortranCompilerTool" Preprocess="preprocessYes"/></FileConfiguration></File>
+			<Tool Name="VFFortranCompilerTool" Preprocess="preprocessYes"/></FileConfiguration></File>
 		<File RelativePath="..\..\..\src\Utilities\Constants.f90"/>
-		<File RelativePath="..\..\..\src\Utilities\genericutils.f90"/>
+		<File RelativePath="..\..\..\src\Utilities\defmacro.F90">
+			<FileConfiguration Name="Debug|Win32">
+			<Tool Name="VFFortranCompilerTool" Preprocess="preprocessYes"/></FileConfiguration></File>
+		<File RelativePath="..\..\..\src\Utilities\DevFeature.f90"/>
+		<File RelativePath="..\..\..\src\Utilities\Message.f90"/>
+		<File RelativePath="..\..\..\src\Utilities\ErrorUtil.f90"/>
 		<File RelativePath="..\..\..\src\Utilities\InputOutput.f90"/>
+		<File RelativePath="..\..\..\src\Utilities\GeomUtil.f90"/>
 		<File RelativePath="..\..\..\src\Utilities\kind.f90"/>
 		<File RelativePath="..\..\..\src\Utilities\List.f90"/>
+		<File RelativePath="..\..\..\src\Utilities\LongLineReader.f90"/>
 		<File RelativePath="..\..\..\src\Utilities\OpenSpec.f90"/>
 		<File RelativePath="..\..\..\src\Utilities\SimVariables.f90"/>
 		<File RelativePath="..\..\..\src\Utilities\Table.f90"/>
@@ -190,5 +201,7 @@
 		<File RelativePath="..\src\TdisVariables.f90"/>
 		<File RelativePath="..\src\TdisWriter.f90"/>
 		<File RelativePath="..\src\UzfPackageWriter.f90"/>
-		<File RelativePath="..\src\WelPackageWriter.f90"/></Filter></Files>
-	<Globals/></VisualStudioProject>
+		<File RelativePath="..\src\WelPackageWriter.f90"/></Filter>
+	</Files>
+	<Globals/>
+</VisualStudioProject>
diff --git a/utils/mf5to6/pymake/extrafiles.txt b/utils/mf5to6/pymake/extrafiles.txt
index 1699e51ed46..f8a3888f945 100644
--- a/utils/mf5to6/pymake/extrafiles.txt
+++ b/utils/mf5to6/pymake/extrafiles.txt
@@ -9,12 +9,17 @@
 ../../../src/Utilities/Constants.f90
 ../../../src/Utilities/SimVariables.f90
 ../../../src/Utilities/compilerversion.F90
-../../../src/Utilities/genericutils.f90
+../../../src/Utilities/Message.f90
+../../../src/Utilities/ErrorUtil.f90
+../../../src/Utilities/GeomUtil.f90
 ../../../src/Utilities/InputOutput.f90
 ../../../src/Utilities/kind.f90
 ../../../src/Utilities/List.f90
+../../../src/Utilities/LongLineReader.f90
+../../../src/Utilities/MathUtil.f90
 ../../../src/Utilities/OpenSpec.f90
 ../../../src/Utilities/defmacro.F90
 ../../../src/Utilities/version.f90
 ../../../src/Utilities/Table.f90
 ../../../src/Utilities/TableTerm.f90
+../../../src/Utilities/DevFeature.f90
diff --git a/utils/mf5to6/src/Connection.f90 b/utils/mf5to6/src/Connection.f90
index 561d737a049..8c0d8fec34b 100644
--- a/utils/mf5to6/src/Connection.f90
+++ b/utils/mf5to6/src/Connection.f90
@@ -67,13 +67,43 @@ subroutine WriteGhostNodeCorrection(this, iu, numalphaj)
     !
     select case (numalphaj)
     case (1)
+      if (this%alphaj1 == 0) then
+        this%k1 = 0
+        this%i1 = 0
+        this%j1 = 0
+      end if
       write(iu,10)this%kp, this%ip, this%jp, this%kc, this%ic, this%jc, &
                   this%k1, this%i1, this%j1, this%alphaj1
     case (2)
+      if (this%alphaj1 == 0.) then
+        this%k1 = 0
+        this%i1 = 0
+        this%j1 = 0
+      end if
+      if (this%alphaj2 == 0.) then
+        this%k2 = 0
+        this%i2 = 0
+        this%j2 = 0
+      end if
       write(iu,20)this%kp, this%ip, this%jp, this%kc, this%ic, this%jc, &
                   this%k1, this%i1, this%j1, this%k2, this%i2, this%j2, &
                   this%alphaj1, this%alphaj2
     case (3)
+      if (this%alphaj1 == 0.) then
+        this%k1 = 0
+        this%i1 = 0
+        this%j1 = 0
+      end if
+      if (this%alphaj2 == 0.) then
+        this%k2 = 0
+        this%i2 = 0
+        this%j2 = 0
+      end if
+      if (this%alphaj12 == 0.) then
+        this%k12 = 0
+        this%i12 = 0
+        this%j12 = 0
+      end if
       write(iu,30)this%kp, this%ip, this%jp, this%kc, this%ic, this%jc, &
                   this%k1, this%i1, this%j1, this%k2, this%i2, this%j2, &
                   this%k12, this%i12, this%j12, this%alphaj1, this%alphaj2, &
diff --git a/utils/mf5to6/src/Exchange.f90 b/utils/mf5to6/src/Exchange.f90
index 9071210c74b..3a5d2f1a7de 100644
--- a/utils/mf5to6/src/Exchange.f90
+++ b/utils/mf5to6/src/Exchange.f90
@@ -5,7 +5,7 @@ module ExchangeModule
   use FileWriterModule, only: FileWriterType
   use GLOBAL, only: NLAY, NROW, NCOL, IBOUND, BOTM, DELC, DELR, LBOTM, NBOTM
   use GlobalVariablesModule, only: LgrBilinear
-  use InputOutputModule, only: get_ijk, get_node
+  use GeomUtilModule, only: get_ijk, get_node
   use LGRMODULE, only: IBFLG, NPLBEG, NPRBEG, NPCBEG, NPLEND, &
                        NPREND, NPCEND, NCPP, NCPPL
   use ModelModule, only: ModelType
diff --git a/utils/mf5to6/src/MF2005/GwfBasSubs.f b/utils/mf5to6/src/MF2005/GwfBasSubs.f
index 01b15a2e4da..2e8adcdd710 100644
--- a/utils/mf5to6/src/MF2005/GwfBasSubs.f
+++ b/utils/mf5to6/src/MF2005/GwfBasSubs.f
@@ -11,7 +11,7 @@ module GwfBasSubs
         use global, only: iout
         use GlobalVariablesModule, only: echo
         use GwfBasModule, only: SGWF2BAS7PNT, SGWF2BAS7PSV
-        use GenericUtilitiesModule, only: write_centered
+        use MessageModule, only: write_message_centered
         use ModelModule, only: ModelType
         use ObsWriterModule, only: ObsWriterType
         use OpenSpecModule, only: ACCESS, ACTION, FORM
@@ -1051,9 +1051,9 @@ SUBROUTINE SGWF2BAS7OPEN(INUNIT,IUNIT,CUNIT,NIUNIT,
           model%iulist = iu
           OPEN(UNIT=IU,FILE=FNAME(1:IFLEN),STATUS='REPLACE',
      1          FORM='FORMATTED',ACCESS='SEQUENTIAL')
-          call write_centered(PROGNAM, 80, iunit=iout)
+          call write_message_centered(PROGNAM, 80, iunit=iout)
           msg = 'Conversion Report'
-          call write_centered(msg, 80, iunit=iout)
+          call write_message_centered(msg, 80, iunit=iout)
           write(iout,1)trim(model%NameFile2005)
           write(iout,2)trim(model%BaseName)
           if (.not. model%ConversionDone) then
diff --git a/utils/mf5to6/src/ModelConverter.f90 b/utils/mf5to6/src/ModelConverter.f90
index 3c1f14555e4..bea004b0de6 100644
--- a/utils/mf5to6/src/ModelConverter.f90
+++ b/utils/mf5to6/src/ModelConverter.f90
@@ -34,8 +34,7 @@ module ModelConverterModule
   use RivObsWriterModule, only: createRivObsWriter, RivObsWriterType
   use GhbObsWriterModule, only: createGhbObsWriter, GhbObsWriterType
   use GlobalVariablesModule, only: echo
-  use SimModule, only: store_error, store_note, store_warning, ustop, &
-                       write_message
+  use SimModule, only: store_error, store_note, store_warning, ustop
   use SimListVariablesModule, only: SimMovers
   use UpwSubsModule, only: GWF2UPW1AR
   use UtilitiesModule, only: GetArgs
diff --git a/utils/mf5to6/src/MultiLayerObsModule.f90 b/utils/mf5to6/src/MultiLayerObsModule.f90
index f8c77064f46..e2c87430a8e 100644
--- a/utils/mf5to6/src/MultiLayerObsModule.f90
+++ b/utils/mf5to6/src/MultiLayerObsModule.f90
@@ -1,8 +1,8 @@
 module MultiLayerObs
-  
-  use ConstantsModule,        only: DONE, MAXCHARLEN
-  use ConstantsPHMFModule,    only: LENOBSNAMENEW
-  use GenericUtilitiesModule, only: is_same
+
+  use ConstantsModule, only: DONE, MAXCHARLEN
+  use ConstantsPHMFModule, only: LENOBSNAMENEW
+  use MathUtilModule, only: is_close
   use ListModule, only: ListType
   use SimModule, only: store_error, ustop
 
@@ -26,7 +26,7 @@ module MultiLayerObs
     procedure, public :: CheckWeightSum
   end type
 
-  contains
+contains
 
   ! Non-type-bound procedures
 
@@ -43,7 +43,7 @@ function CastAsLayerObsType(obj) result(res)
     end select
     return
   end function CastAsLayerObsType
-  
+
   subroutine ConstructLayerObs(newLayerObs, layobname, layer, weight)
     ! dummy
     type(LayerObsType), pointer :: newLayerObs
@@ -51,7 +51,7 @@ subroutine ConstructLayerObs(newLayerObs, layobname, layer, weight)
     integer, intent(in) :: layer
     double precision, intent(in) :: weight
     !
-    allocate(newLayerObs)
+    allocate (newLayerObs)
     newLayerObs%lobsname = layobname
     newLayerObs%layer = layer
     newLayerObs%weight = weight
@@ -71,7 +71,7 @@ subroutine AddLayerObsToList(list, layerobs)
     !
     return
   end subroutine AddLayerObsToList
-  
+
   function GetLayerObsFromList(list, indx) result(res)
     ! dummy
     type(ListType), intent(inout) :: list
@@ -88,18 +88,18 @@ function GetLayerObsFromList(list, indx) result(res)
     !
     return
   end function GetLayerObsFromList
-  
+
   subroutine ConstructMLObs(newMLObs, obsname)
     ! dummy
     type(MLObsType), pointer, intent(inout) :: newMLObs
     character(len=LENOBSNAMENEW), intent(in) :: obsname
     !
-    allocate(newMLObs)
+    allocate (newMLObs)
     newMLObs%mlobsname = obsname
     !
     return
   end subroutine ConstructMLObs
-  
+
   subroutine AddMLObsToList(list, mlobs)
     ! dummy
     type(ListType), intent(inout) :: list
@@ -112,7 +112,7 @@ subroutine AddMLObsToList(list, mlobs)
     !
     return
   end subroutine AddMLObsToList
-  
+
   function GetMLObsFromList(list, indx) result(res)
     ! dummy
     type(ListType), intent(inout) :: list
@@ -129,37 +129,37 @@ function GetMLObsFromList(list, indx) result(res)
     !
     return
   end function GetMLObsFromList
-  
+
   ! Type-bound procedures of MLObsType
-  
+
   subroutine CheckWeightSum(this)
     ! dummy
     class(MLObsType) :: this
     ! local
     double precision :: weightsum
     integer :: i, nlayers
-    type(LayerObsType), pointer :: layobs =>  null()
+    type(LayerObsType), pointer :: layobs => null()
     character(len=MAXCHARLEN) :: ermsg
     ! formats
-    10 format('Weights of layer observations do not sum to 1.0 for', &
-              ' multilayer observation: ',a)
+10  format('Weights of layer observations do not sum to 1.0 for', &
+           ' multilayer observation: ', a)
     !
     if (this%summ) return
     !
     weightsum = 0.0d0
     nlayers = this%LayerObsList%Count()
-    do i=1,nlayers
+    do i = 1, nlayers
       layobs => GetLayerObsFromList(this%LayerObsList, i)
       weightsum = weightsum + layobs%weight
-    enddo
+    end do
     !
-    if (.not. is_same(weightsum, DONE)) then
-      write(ermsg,10)trim(this%mlobsname)
+    if (.not. is_close(weightsum, DONE)) then
+      write (ermsg, 10) trim(this%mlobsname)
       call store_error(ermsg)
       call ustop()
-    endif
+    end if
     !
     return
   end subroutine
-  
+
 end module MultiLayerObs
diff --git a/utils/mf5to6/src/Preproc/Discretization3D.f90 b/utils/mf5to6/src/Preproc/Discretization3D.f90
index 38fe5b57304..0d373c8ebae 100644
--- a/utils/mf5to6/src/Preproc/Discretization3D.f90
+++ b/utils/mf5to6/src/Preproc/Discretization3D.f90
@@ -5,7 +5,8 @@ module DnmDis3dModule
   use ConstantsPHMFModule,       only: PI
   use DnmDisBaseModule,          only: DisBaseType
   use GlobalVariablesPHMFModule, only: verbose
-  use InputOutputModule,         only: get_ijk, get_node, URWORD
+  use GeomUtilModule,            only: get_ijk, get_node
+  use InputOutputModule,         only: URWORD
   use SimModule,                 only: count_errors, store_error, &
                                        store_error_unit, ustop
   implicit none
@@ -545,7 +546,6 @@ subroutine nodeu_to_string(this, nodeu, str)
 !
 !    SPECIFICATIONS:
 ! ------------------------------------------------------------------------------
-    use InputOutputModule, only: get_ijk
     implicit none
     class(Dis3dType) :: this
     integer, intent(in) :: nodeu
@@ -617,7 +617,6 @@ integer function get_nodenumber_idx3(this, k, i, j, icheck)                  &
 !    SPECIFICATIONS:
 ! ------------------------------------------------------------------------------
     use ConstantsModule, only: LINELENGTH
-    use InputOutputModule, only: get_node
     implicit none
     ! dummy
     class(Dis3dType), intent(in) :: this
diff --git a/utils/mf5to6/src/Preproc/DiscretizationBasePHMF.f90 b/utils/mf5to6/src/Preproc/DiscretizationBasePHMF.f90
index 5bc906a4b21..3158b4a3c7e 100644
--- a/utils/mf5to6/src/Preproc/DiscretizationBasePHMF.f90
+++ b/utils/mf5to6/src/Preproc/DiscretizationBasePHMF.f90
@@ -5,6 +5,7 @@ module DnmDisBaseModule
   use InputOutputModule,  only: URWORD
   use SimModule,          only: count_errors, store_error, store_error_unit, &
                                 ustop
+  use GeomUtilModule, only: get_node
   implicit none
   private
   public :: DisBaseType
@@ -504,7 +505,6 @@ function get_nodenumber_idx2(this, k, j, icheck) result(nodenumber)
 !    SPECIFICATIONS:
 ! ------------------------------------------------------------------------------
     use SimModule, only: ustop, store_error
-    use InputOutputModule, only: get_node
     implicit none
     ! Dummy arguments
     class(DisBaseType), intent(in) :: this
diff --git a/utils/mf5to6/src/Preproc/ObsBlock.f90 b/utils/mf5to6/src/Preproc/ObsBlock.f90
index 9a16e3bfd50..c4e51a3562e 100644
--- a/utils/mf5to6/src/Preproc/ObsBlock.f90
+++ b/utils/mf5to6/src/Preproc/ObsBlock.f90
@@ -3,11 +3,11 @@ module ObsBlockModule
   use BlockParserModule,         only: BlockParserType
   use ConstantsModule,           only: DONE, DZERO, &
                                        LINELENGTH, MAXCHARLEN, LENOBSNAME
-  use GenericUtilitiesModule,    only: is_same
+  use MathUtilModule,    only: is_close
   use ConstantsPHMFModule,       only: CONTINUOUS, SINGLE, LENOBSNAMENEW
   use DnmDis3dModule,            only: Dis3dType
   use GlobalVariablesPHMFModule, only: verbose
-  use InputOutputModule,         only: UPCASE, URWORD, uterminate_block
+  use InputOutputModule,         only: UPCASE, URWORD
   use ListModule,                only: ListType
   use ObserveModule,             only: ObserveType, AddObserveToList, &
                                        GetObserveFromList, ConstructObservation
@@ -184,7 +184,7 @@ subroutine process_block(this, insertLine, WriteBeginEnd, parser)
         iadjrow = 0
         jadjcol = 0
         !
-        if (.not. is_same(xoff, DZERO)) then
+        if (.not. is_close(xoff, DZERO)) then
           if (xoff > DZERO) then
             if (jcol < ncol) then
               if (dis3d%idomain(jcol+1, irow, layer) == 1) then
@@ -202,7 +202,7 @@ subroutine process_block(this, insertLine, WriteBeginEnd, parser)
           endif
         endif
         !
-        if (.not. is_same(yoff, DZERO)) then
+        if (.not. is_close(yoff, DZERO)) then
           if (yoff > DZERO) then
             if (irow > 1) then
               if (dis3d%idomain(jcol, irow-1, layer) == 1) then
diff --git a/utils/mf5to6/src/Preproc/ObservePHMF.f90 b/utils/mf5to6/src/Preproc/ObservePHMF.f90
index d35fd18079d..c50c7ad5f8d 100644
--- a/utils/mf5to6/src/Preproc/ObservePHMF.f90
+++ b/utils/mf5to6/src/Preproc/ObservePHMF.f90
@@ -15,7 +15,7 @@ module ObserveModule
   use ConstantsModule,        only: DONE, DZERO, LENOBSNAME,  &
                                     LENOBSTYPE, MAXCHARLEN
   use ConstantsPHMFModule,    only: LENOBSNAMENEW, HUGEDBL, HDRYDEFAULT
-  use GenericUtilitiesModule, only: is_same
+  use MathUtilModule,         only: is_close
   use ListModule,             only: ListType
   use SimModule,              only: store_warning, store_error, &
                                     store_error_unit, ustop
@@ -206,7 +206,7 @@ subroutine CalcSimVal(this, itime)
       sumweights = DZERO
       k = 0
       do i=1,nsrc
-        if (is_same(this%srcvals(itime, i), this%hdry)) then
+        if (is_close(this%srcvals(itime, i), this%hdry)) then
           k = k + 1
           weights(i) = DZERO
         else
diff --git a/utils/mf5to6/src/Preproc/Preproc.f90 b/utils/mf5to6/src/Preproc/Preproc.f90
index c320028b428..d840b84beb6 100644
--- a/utils/mf5to6/src/Preproc/Preproc.f90
+++ b/utils/mf5to6/src/Preproc/Preproc.f90
@@ -14,15 +14,13 @@ module PreprocModule
   use GLOBAL,                    only: NCOL, NROW, DELC, DELR
   use globalPHMF,                only: ioutPHMF, outfile
   use GlobalVariablesPHMFModule, only: prognamPHMF, verbose, vnam
-  use InputOutputModule,         only: GetUnit, uget_block, urword, &
-                                       uterminate_block, GetUnit, openfile, &
-                                       uget_any_block
+  use InputOutputModule,         only: GetUnit, urword, GetUnit, openfile
   use ListModule,                only: ListType
   use ObsBlockModule,            only: ObsBlockType, ConstructObsBlockType, &
                                        AddObsBlockToList, GetObsBlockFromList
   use OpenSpecModule,            only: ACCESS, ACTION, FORM
   use SimModule,                 only: count_errors, print_notes, store_error, &
-                                       store_error_unit, ustop, write_message
+                                       store_error_unit, ustop
   use UtilitiesModule,           only: get_extension, CalcContribFactors
 
   implicit none
@@ -203,8 +201,6 @@ subroutine read_options(this)
     ierr = 0
     !
     ! -- get BEGIN line of OPTIONS block
-!    call uget_block(iin, 0, blockTypeWanted, ierr, found, &
-!                    lloc, line, iuext, continueread)
     call this%parser%GetBlock('OPTIONS', found, ierr, supportOpenClose=.true.)
     if (ierr /= 0) then
       ! end of file
@@ -733,7 +729,6 @@ subroutine read_any_block(this, iu ,k, eof, dis3d, WriteBeginEnd)
     !
     ! -- Read any block as long as it's SINGLE or CONTINUOUS.
     lloc = 1
-!    call uget_any_block(iu, this%iout, isfound, lloc, line, ctagfound, iuext)
     call this%parser%GetBlock('*', isfound, ierr, .true., &
                               .false., ctagfound)
     if (.not. isfound) then
diff --git a/utils/mf5to6/src/Preproc/Utilities.f90 b/utils/mf5to6/src/Preproc/Utilities.f90
index 3d97b4c0618..13e7ec9c3f4 100644
--- a/utils/mf5to6/src/Preproc/Utilities.f90
+++ b/utils/mf5to6/src/Preproc/Utilities.f90
@@ -3,8 +3,7 @@ module UtilitiesModule
   use ConstantsModule, only: MAXCHARLEN, DZERO, MAXCHARLEN
   use GlobalVariablesModule, only: optfile, PathToPostObsMf, ScriptType, &
                                    verbose, echo
-  use InputOutputModule, only: GetUnit, openfile, UPCASE, URWORD, &
-                               uget_block, uterminate_block, u9rdcom
+  use InputOutputModule, only: GetUnit, openfile, UPCASE, URWORD
   use SimModule, onlY: store_error, store_note, store_warning, ustop
 
   private
@@ -15,7 +14,7 @@ module UtilitiesModule
             BuildArrayFormat, Write1dValues, &
             Write2dValues, Write3dValues, findcell, &
             close_file, GreaterOf, GreatestOf, RemoveElement, &
-            get_extension, ReadMf5to6Options, count_file_records, &
+            get_extension, count_file_records, &
             CalcContribFactors, PhmfOption
 
   interface RemoveElement
@@ -876,65 +875,6 @@ subroutine get_extension(name, ext)
     return
   end subroutine get_extension
 
-  subroutine ReadMf5to6Options()
-    implicit none
-    ! local
-    integer :: ierr, istart, istop, iu, idum, icol
-    double precision :: rdum
-    character(len=MAXCHARLEN) :: ermsg
-    character(len=:), allocatable :: line
-    character(len=10) :: stype
-    logical :: continueread=.true., found
-    integer :: iuext
-    !
-    if (optfile /= '') then
-      iu = GetUnit()
-      call openfile(iu, 0, optfile, 'OPTIONS', filstat_opt='OLD')
-      call uget_block(iu, 0, 'OPTIONS', ierr, found, icol, line, iuext, &
-                      continueread)
-      if (found) then
-        do
-          icol = 1
-          call u9rdcom(iu, 0, line, ierr)
-          call urword(line, icol, istart, istop, 1, idum, rdum, 0, iu)
-          select case (line(istart:istop))
-          case ('PATHTOPOSTOBSMF')
-            call urword(line, icol, istart, istop, 0, idum, rdum, 0, iu)
-            PathToPostObsMf = line(istart:istop)
-          case ('SCRIPT')
-            call urword(line, icol, istart, istop, 1, idum, rdum, 0, iu)
-            stype = line(istart:istop)
-            select case (stype)
-            case ('BATCH')
-              ScriptType = 'BATCH'
-            case ('PYTHON')
-              ScriptType = 'PYTHON'
-            case default
-              ermsg = 'Unknown Script option: ' // line(istart:istop)
-              call store_error(ermsg)
-              call ustop()
-            end select
-          case default
-            ermsg = 'Unknown Mf5to6 option: ' // line(istart:istop)
-            call store_error(ermsg)
-            call ustop()
-          case ('END','BEGIN')
-            call uterminate_block(iu,0,line(istart:istop),    &
-                                  'OPTIONS', icol,line,ierr, iuext)
-            if(ierr==0) exit
-          end select
-        enddo
-        close(iu)
-      else
-        ermsg = 'Mf5to6 options file not found: ' // trim(optfile)
-        call store_error(ermsg)
-        call ustop()
-      endif
-    endif
-    !
-    return
-  end subroutine ReadMf5to6Options
-
   function count_file_records(filename) result(nrecs)
     ! Open a text file, count the number of records in it, and close the file.
     ! dummy
diff --git a/utils/mf5to6/src/mf5to6.f90 b/utils/mf5to6/src/mf5to6.f90
index 1e7b07dc8da..ecf2131c8de 100644
--- a/utils/mf5to6/src/mf5to6.f90
+++ b/utils/mf5to6/src/mf5to6.f90
@@ -19,7 +19,7 @@ program mf5to6
   use SimFileWriterModule, only: SimFileWriterType
   use SimModule, only: ustop
   use SimListVariablesModule, only: SimMovers
-  use UtilitiesModule, only: GetArgs, ReadMf5to6Options, PhmfOption
+  use UtilitiesModule, only: GetArgs, PhmfOption
   !
   implicit none
   integer :: iexg, igrid, ispw, iu
@@ -69,7 +69,6 @@ program mf5to6
   ! provide a command-prompt instruction that will run PostObsMF, or maybe
   ! generate a batch or python file (could also be an option) that would
   ! run PostObsMF (twice, if there are multilayer head observations).
-  if (SupportPreproc) call ReadMf5to6Options()
   SimFileWriter%BaseName = basnam
   if (ilgr > 0) then
     ! LGR is active; read and initialize parent and all children.
diff --git a/utils/zonebudget/make/makedefaults b/utils/zonebudget/make/makedefaults
index 919f5ed9b06..c0eadf7ac21 100644
--- a/utils/zonebudget/make/makedefaults
+++ b/utils/zonebudget/make/makedefaults
@@ -1,4 +1,4 @@
-# makedefaults created by pymake (version 1.2.7) for the 'zbud6' executable.
+# makedefaults created by pymake (version 1.2.9.dev0) for the 'zbud6' executable.
 
 # determine OS
 ifeq ($(OS), Windows_NT)
@@ -57,19 +57,16 @@ OPTLEVEL ?= -O2
 # set the fortran flags
 ifeq ($(detected_OS), Windows)
 	ifeq ($(FC), gfortran)
-		FFLAGS ?= -static -fbacktrace -ffpe-summary=overflow -ffpe-trap=overflow,zero,invalid $(OS_macro) -fall-intrinsics -Wtabs -Wline-truncation -Wunused-label -Wunused-variable -pedantic -std=f2008 -Wcharacter-truncation -cpp
+		FFLAGS ?= -static -fbacktrace -ffpe-summary=overflow -ffpe-trap=overflow,zero,invalid -fall-intrinsics -pedantic -Wcharacter-truncation $(OS_macro) -Wtabs -Wline-truncation -Wunused-label -Wunused-variable -std=f2008 -cpp
 	endif
 else
 	ifeq ($(FC), gfortran)
-		FFLAGS ?= -fbacktrace -ffpe-summary=overflow -ffpe-trap=overflow,zero,invalid $(OS_macro) -fall-intrinsics -Wtabs -Wline-truncation -Wunused-label -Wunused-variable -pedantic -std=f2008 -Wcharacter-truncation -cpp
+		FFLAGS ?= -fbacktrace -ffpe-summary=overflow -ffpe-trap=overflow,zero,invalid -fall-intrinsics -pedantic -Wcharacter-truncation $(OS_macro) -Wtabs -Wline-truncation -Wunused-label -Wunused-variable -std=f2008 -cpp
 	endif
 	ifeq ($(FC), $(filter $(FC), ifort mpiifort))
-		FFLAGS ?= -no-heap-arrays -fpe0 -traceback -fpp
+		FFLAGS ?= -no-heap-arrays -fpe0 -traceback -Qdiag-disable:7416 -Qdiag-disable:7025 -Qdiag-disable:5268 -fpp
 		MODSWITCH = -module $(MODDIR)
 	endif
-	ifeq ($(FC), $(filter $(FC), ftn))
-		FFLAGS ?= -h noheap_allocate
-	endif
 endif
 
 # set the ldflgs
@@ -84,9 +81,6 @@ else
 	ifeq ($(FC), $(filter $(FC), ifort mpiifort))
 		LDFLAGS ?= -lc
 	endif
-	ifeq ($(FC), $(filter $(FC), ftn))
-		LDFLAGS ?= -lc
-	endif
 endif
 
 # check for Windows error condition
diff --git a/utils/zonebudget/make/makefile b/utils/zonebudget/make/makefile
index 092dc3b0294..8a24ed1c082 100644
--- a/utils/zonebudget/make/makefile
+++ b/utils/zonebudget/make/makefile
@@ -1,4 +1,4 @@
-# makefile created by pymake (version 1.2.7) for the 'zbud6' executable.
+# makefile created by pymake (version 1.2.9.dev0) for the 'zbud6' executable.
 
 
 include ./makedefaults
@@ -16,16 +16,18 @@ ${SOURCEDIR2}
 OBJECTS = \
 $(OBJDIR)/kind.o \
 $(OBJDIR)/Constants.o \
+$(OBJDIR)/ErrorUtil.o \
 $(OBJDIR)/SimVariables.o \
-$(OBJDIR)/genericutils.o \
+$(OBJDIR)/ArrayHandlers.o \
+$(OBJDIR)/Message.o \
 $(OBJDIR)/defmacro.o \
 $(OBJDIR)/compilerversion.o \
-$(OBJDIR)/ArrayHandlers.o \
 $(OBJDIR)/version.o \
-$(OBJDIR)/Message.o \
 $(OBJDIR)/Sim.o \
 $(OBJDIR)/OpenSpec.o \
 $(OBJDIR)/InputOutput.o \
+$(OBJDIR)/LongLineReader.o \
+$(OBJDIR)/DevFeature.o \
 $(OBJDIR)/sort.o \
 $(OBJDIR)/BlockParser.o \
 $(OBJDIR)/ArrayReaders.o \
@@ -34,6 +36,8 @@ $(OBJDIR)/Budget.o \
 $(OBJDIR)/zoneoutput.o \
 $(OBJDIR)/grb.o \
 $(OBJDIR)/budgetdata.o \
+$(OBJDIR)/MathUtil.o \
+$(OBJDIR)/GeomUtil.o \
 $(OBJDIR)/zbud6.o
 
 # Define the objects that make up the program
diff --git a/utils/zonebudget/msvs/zonebudget.vfproj b/utils/zonebudget/msvs/zonebudget.vfproj
index 682849e3f29..f6e8613efd2 100644
--- a/utils/zonebudget/msvs/zonebudget.vfproj
+++ b/utils/zonebudget/msvs/zonebudget.vfproj
@@ -1,28 +1,32 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <VisualStudioProject ProjectCreator="Intel Fortran" Keyword="Console Application" Version="11.0" ProjectIdGuid="{E7756A4E-003C-4D3D-B618-CC2BE6D20B04}">
 	<Platforms>
-		<Platform Name="Win32"/></Platforms>
+		<Platform Name="Win32"/>
+	</Platforms>
 	<Configurations>
 		<Configuration Name="Debug|Win32">
-				<Tool Name="VFFortranCompilerTool" SuppressStartupBanner="true" DebugInformationFormat="debugEnabled" Optimization="optimizeDisabled" WarnDeclarations="true" WarnUnusedVariables="true" WarnTruncateSource="true" WarnUnalignedData="false" WarnUncalled="true" WarnInterfaces="true" Traceback="true" BoundsCheck="true" StackFrameCheck="true" RuntimeLibrary="rtMultiThreadedDebugDLL"/>
-				<Tool Name="VFLinkerTool" LinkIncremental="linkIncrementalNo" SuppressStartupBanner="true" GenerateDebugInformation="true" SubSystem="subSystemConsole"/>
-				<Tool Name="VFResourceCompilerTool"/>
-				<Tool Name="VFMidlTool" SuppressStartupBanner="true"/>
-				<Tool Name="VFCustomBuildTool"/>
-				<Tool Name="VFPreLinkEventTool"/>
-				<Tool Name="VFPreBuildEventTool"/>
-				<Tool Name="VFPostBuildEventTool"/>
-				<Tool Name="VFManifestTool" SuppressStartupBanner="true"/></Configuration>
+			<Tool Name="VFFortranCompilerTool" SuppressStartupBanner="true" DebugInformationFormat="debugEnabled" Optimization="optimizeDisabled" WarnDeclarations="true" WarnUnusedVariables="true" WarnTruncateSource="true" WarnUnalignedData="false" WarnUncalled="true" WarnInterfaces="true" Traceback="true" BoundsCheck="true" StackFrameCheck="true" RuntimeLibrary="rtMultiThreadedDebugDLL"/>
+			<Tool Name="VFLinkerTool" LinkIncremental="linkIncrementalNo" SuppressStartupBanner="true" GenerateDebugInformation="true" SubSystem="subSystemConsole"/>
+			<Tool Name="VFResourceCompilerTool"/>
+			<Tool Name="VFMidlTool" SuppressStartupBanner="true"/>
+			<Tool Name="VFCustomBuildTool"/>
+			<Tool Name="VFPreLinkEventTool"/>
+			<Tool Name="VFPreBuildEventTool"/>
+			<Tool Name="VFPostBuildEventTool"/>
+			<Tool Name="VFManifestTool" SuppressStartupBanner="true"/>
+		</Configuration>
 		<Configuration Name="Release|Win32">
-				<Tool Name="VFFortranCompilerTool" SuppressStartupBanner="true" RuntimeLibrary="rtMultiThreadedDLL"/>
-				<Tool Name="VFLinkerTool" LinkIncremental="linkIncrementalNo" SuppressStartupBanner="true" SubSystem="subSystemConsole"/>
-				<Tool Name="VFResourceCompilerTool"/>
-				<Tool Name="VFMidlTool" SuppressStartupBanner="true"/>
-				<Tool Name="VFCustomBuildTool"/>
-				<Tool Name="VFPreLinkEventTool"/>
-				<Tool Name="VFPreBuildEventTool"/>
-				<Tool Name="VFPostBuildEventTool"/>
-				<Tool Name="VFManifestTool" SuppressStartupBanner="true"/></Configuration></Configurations>
+			<Tool Name="VFFortranCompilerTool" SuppressStartupBanner="true" RuntimeLibrary="rtMultiThreadedDLL"/>
+			<Tool Name="VFLinkerTool" LinkIncremental="linkIncrementalNo" SuppressStartupBanner="true" SubSystem="subSystemConsole"/>
+			<Tool Name="VFResourceCompilerTool"/>
+			<Tool Name="VFMidlTool" SuppressStartupBanner="true"/>
+			<Tool Name="VFCustomBuildTool"/>
+			<Tool Name="VFPreLinkEventTool"/>
+			<Tool Name="VFPreBuildEventTool"/>
+			<Tool Name="VFPostBuildEventTool"/>
+			<Tool Name="VFManifestTool" SuppressStartupBanner="true"/>
+		</Configuration>
+	</Configurations>
 	<Files>
 		<Filter Name="Header Files" Filter="fi;fd;h;inc"/>
 		<Filter Name="Resource Files" Filter="rc;ico;cur;bmp;dlg;rc2;rct;bin;rgs;gif;jpg;jpeg;jpe"/>
@@ -34,14 +38,17 @@
 		<File RelativePath="..\..\..\src\Utilities\Budget.f90"/>
 		<File RelativePath="..\..\..\src\Utilities\compilerversion.F90">
 			<FileConfiguration Name="Debug|Win32">
-				<Tool Name="VFFortranCompilerTool" Preprocess="preprocessYes"/></FileConfiguration></File>
+			<Tool Name="VFFortranCompilerTool" Preprocess="preprocessYes"/></FileConfiguration></File>
 		<File RelativePath="..\..\..\src\Utilities\Constants.f90"/>
 		<File RelativePath="..\..\..\src\Utilities\defmacro.F90">
 			<FileConfiguration Name="Debug|Win32">
-				<Tool Name="VFFortranCompilerTool" Preprocess="preprocessYes"/></FileConfiguration></File>
-		<File RelativePath="..\..\..\src\Utilities\genericutils.f90"/>
+			<Tool Name="VFFortranCompilerTool" Preprocess="preprocessYes"/></FileConfiguration></File>
+		<File RelativePath="..\..\..\src\Utilities\DevFeature.f90"/>
+		<File RelativePath="..\..\..\src\Utilities\ErrorUtil.f90"/>
 		<File RelativePath="..\..\..\src\Utilities\InputOutput.f90"/>
+		<File RelativePath="..\..\..\src\Utilities\GeomUtil.f90"/>
 		<File RelativePath="..\..\..\src\Utilities\kind.f90"/>
+		<File RelativePath="..\..\..\src\Utilities\LongLineReader.f90"/>
 		<File RelativePath="..\..\..\src\Utilities\Message.f90"/>
 		<File RelativePath="..\..\..\src\Utilities\OpenSpec.f90"/>
 		<File RelativePath="..\..\..\src\Utilities\Sim.f90"/>
@@ -52,5 +59,7 @@
 		<File RelativePath="..\src\grb.f90"/>
 		<File RelativePath="..\src\zbud6.f90"/>
 		<File RelativePath="..\src\zone.f90"/>
-		<File RelativePath="..\src\zoneoutput.f90"/></Filter></Files>
-	<Globals/></VisualStudioProject>
+		<File RelativePath="..\src\zoneoutput.f90"/></Filter>
+	</Files>
+	<Globals/>
+</VisualStudioProject>
diff --git a/utils/zonebudget/pymake/extrafiles.txt b/utils/zonebudget/pymake/extrafiles.txt
index c4cfdf23967..54d11147ff3 100644
--- a/utils/zonebudget/pymake/extrafiles.txt
+++ b/utils/zonebudget/pymake/extrafiles.txt
@@ -4,13 +4,17 @@
 ../../../src/Utilities/Budget.f90
 ../../../src/Utilities/Constants.f90
 ../../../src/Utilities/compilerversion.F90
-../../../src/Utilities/genericutils.f90
+../../../src/Utilities/ErrorUtil.f90
+../../../src/Utilities/GeomUtil.f90
+../../../src/Utilities/MathUtil.f90
 ../../../src/Utilities/InputOutput.f90
 ../../../src/Utilities/kind.f90
+../../../src/Utilities/LongLineReader.f90
 ../../../src/Utilities/OpenSpec.f90
 ../../../src/Utilities/sort.f90
-../../../src/Utilities/Message.f90
 ../../../src/Utilities/defmacro.F90
 ../../../src/Utilities/Sim.f90
 ../../../src/Utilities/SimVariables.f90
 ../../../src/Utilities/version.f90
+../../../src/Utilities/DevFeature.f90
+../../../src/Utilities/Message.f90
diff --git a/utils/zonebudget/src/zbud6.f90 b/utils/zonebudget/src/zbud6.f90
index fedccae4ee9..29a5c98e85e 100644
--- a/utils/zonebudget/src/zbud6.f90
+++ b/utils/zonebudget/src/zbud6.f90
@@ -4,7 +4,7 @@ program zonbudmf6
   use VersionModule, only: VERSION
   use SimVariablesModule, only: iout, errmsg
   use SimModule, only: store_error
-  use GenericUtilitiesModule, only: sim_message, write_centered
+  use MessageModule, only: write_message, write_message_centered
   use InputOutputModule, only: openfile
 
   implicit none
@@ -21,9 +21,9 @@ program zonbudmf6
   logical :: exists
 
   ! -- Write title to screen
-  call write_centered('ZONEBUDGET'//mfvnam, 80)
-  call write_centered('U.S. GEOLOGICAL SURVEY', 80)
-  call write_centered('VERSION '//VERSION, 80)
+  call write_message_centered('ZONEBUDGET'//mfvnam, 80)
+  call write_message_centered('U.S. GEOLOGICAL SURVEY', 80)
+  call write_message_centered('VERSION '//VERSION, 80)
   !
   ! -- Find name of zone budget name file and lst file
   fnam = 'zbud.nam'
@@ -37,9 +37,9 @@ program zonbudmf6
   ! -- Open list file and write title
   iout = iunit_lst
   call openfile(iunit_lst, 0, flst, 'LIST', filstat_opt='REPLACE')
-  call write_centered('ZONEBUDGET'//mfvnam, 80, iunit=iout)
-  call write_centered('U.S. GEOLOGICAL SURVEY', 80, iunit=iout)
-  call write_centered('VERSION '//VERSION, 80, iunit=iout)
+  call write_message_centered('ZONEBUDGET'//mfvnam, 80, iunit=iout)
+  call write_message_centered('U.S. GEOLOGICAL SURVEY', 80, iunit=iout)
+  call write_message_centered('VERSION '//VERSION, 80, iunit=iout)
   !
   ! -- Open name file, read name file, and open csv file
   call openfile(iunit_nam, iout, fnam, 'NAM')
@@ -54,7 +54,7 @@ program zonbudmf6
   close (iunit_lst)
   close (iunit_csv)
   write (line, '(a)') 'Normal Termination'
-  call sim_message(line, skipbefore=1)
+  call write_message(line, skipbefore=1)
   !
   ! -- end of program
 end program zonbudmf6
@@ -144,7 +144,6 @@ subroutine process_budget(iunit_csv, iunit_bud, iunit_zon, iunit_grb)
   use KindModule
   use ConstantsModule, only: LINELENGTH
   use SimVariablesModule, only: iout, errmsg
-  use GenericUtilitiesModule, only: sim_message
   use SimModule, only: store_error
   use BudgetDataModule, only: budgetdata_init, budgetdata_read, &
                               budgetdata_finalize, &
@@ -160,6 +159,7 @@ subroutine process_budget(iunit_csv, iunit_bud, iunit_zon, iunit_grb)
   use ZoneOutputModule, only: zoneoutput_init, zoneoutput_write, &
                               zoneoutput_finalize
   use GrbModule, only: read_grb
+  use MessageModule, only: write_message, write_message_centered
   implicit none
   ! -- dummy
   integer, intent(in) :: iunit_csv
@@ -245,7 +245,7 @@ subroutine process_budget(iunit_csv, iunit_bud, iunit_zon, iunit_grb)
       end if
       !
       ! -- write message and check
-      call sim_message(cdot, advance=.FALSE.)
+      call write_message(text=cdot, advance=.FALSE.)
       if (itime == 1) then
         budtxtarray(ibudterm) = budtxt
         packagenamearray(ibudterm) = dstpackagename
@@ -298,7 +298,7 @@ subroutine process_budget(iunit_csv, iunit_bud, iunit_zon, iunit_grb)
   end do timeloop
   !
   ! -- Finalize
-  call sim_message(cdot)
+  call write_message(text=cdot)
   call budgetdata_finalize()
   call zoneoutput_finalize()
   call zone_finalize()
diff --git a/version.txt b/version.txt
index b063daa0c02..8e0a2119a7d 100644
--- a/version.txt
+++ b/version.txt
@@ -1,10 +1 @@
-# MODFLOW 6 version file automatically created using...update_version.py
-# created on...June 28, 2023 19:45:12
-
-major = 6
-minor = 4
-micro = 2
-label = ''
-__version__ = '{:d}.{:d}.{:d}'.format(major, minor, micro)
-if label:
-	__version__ += '{}{}'.format(__version__, label)
\ No newline at end of file
+6.4.3
\ No newline at end of file