diff --git a/.github/workflows/integration.yml b/.github/workflows/integration.yml
index 277c9fd..1d030fb 100644
--- a/.github/workflows/integration.yml
+++ b/.github/workflows/integration.yml
@@ -28,13 +28,15 @@ jobs:
           repository: MODFLOW-ORG/modflow6
           path: modflow6
 
-      - name: Setup Micromamba
-        uses: mamba-org/setup-micromamba@v1
+      - name: Setup pixi
+        uses: prefix-dev/setup-pixi@v0.9.1
         with:
-          environment-file: modflow6/environment.yml
-          cache-environment: true
-          cache-downloads: true
-          init-shell: bash
+          pixi-version: v0.41.4
+          manifest-path: modflow6/pixi.toml
+
+      - name: Custom pixi install
+        working-directory: modflow6
+        run: pixi run install
 
       - name: Setup ${{ contains(fromJSON('["macos-14"]'), matrix.os) && 'gcc' || 'intel-classic' }} ${{ contains(fromJSON('["macos-14"]'), matrix.os) && env.GCC_V || env.INTEL_V }}
         uses: fortran-lang/setup-fortran@v1
@@ -69,13 +71,12 @@ jobs:
           if [[ "${{ matrix.os }}" == "macos-14" ]]; then
             setupargs="$setupargs -Doptimization=1"
           fi
-          meson setup builddir $setupargs
-          meson install -C builddir
+          pixi run build builddir $setupargs
       
       - name: Get OS tag
         id: ostag
         run: |
-          ostag=$(python -c "from modflow_devtools.ostags import get_ostag; print(get_ostag())")
+          ostag=$(pixi run --manifest-path modflow6/pixi.toml python -c "from modflow_devtools.ostags import get_ostag; print(get_ostag())")
           echo "ostag=$ostag" >> $GITHUB_OUTPUT
 
       - name: Build programs
@@ -86,12 +87,12 @@ jobs:
           command: |
             ostag="${{ steps.ostag.outputs.ostag }}"
             mkdir $ostag
-            make-program : --appdir $ostag -ex gridgen --zip $ostag.zip --verbose
-            make-program mf2005,mflgr,mfnwt,mfusg --appdir $ostag --double --keep --zip $ostag.zip --verbose
+            pixi run --manifest-path modflow6/pixi.toml make-program : --appdir $ostag --exclude gridgen --zip $ostag.zip --verbose
+            pixi run --manifest-path modflow6/pixi.toml make-program mf2005,mflgr,mfnwt,mfusg --appdir $ostag --double --keep --zip $ostag.zip --verbose
             if [[ "${{ matrix.os }}" == "macos-14" ]]; then
-              make-program mf6 --appdir $ostag --keep --zip $ostag.zip --verbose --fflags='-O1'
+              pixi run --manifest-path modflow6/pixi.toml make-program mf6 --appdir $ostag --keep --zip $ostag.zip --verbose --fflags='-O1'
             fi
-            make-code-json --appdir $ostag --zip $ostag.zip --verbose
+            pixi run --manifest-path modflow6/pixi.toml make-code-json --appdir $ostag --zip $ostag.zip --verbose
 
       - name: Move programs
         run: |
@@ -150,9 +151,9 @@ jobs:
             ./code.md
 
       - name: Update flopy
-        working-directory: modflow6/autotest
-        run: python update_flopy.py
+        working-directory: modflow6
+        run: pixi run update-flopy
 
       - name: Test modflow6
-        working-directory: modflow6/autotest
-        run: pytest -v -n auto -m "not developmode" --durations 0
+        working-directory: modflow6
+        run: pixi run autotest -m "not developmode"
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 61e5e51..4f83d3a 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -24,8 +24,11 @@ jobs:
         shell: bash
 
     steps:
-      - name: Checkout repo
-        uses: actions/checkout@v4
+      - name: Checkout modflow6
+        uses: actions/checkout@v5
+        with:
+          repository: MODFLOW-ORG/modflow6
+          path: modflow6
 
       - name: Setup ${{ contains(fromJSON('["macos-14"]'), matrix.os) && 'gcc' || 'intel-classic' }} ${{ contains(fromJSON('["macos-14"]'), matrix.os) && env.GCC_V || env.INTEL_V }}
         uses: fortran-lang/setup-fortran@v1
@@ -65,23 +68,26 @@ jobs:
           echo "${{ github.repository }} version ${{ steps.tag.outputs.tag }}"
           echo "RELEASE_VERSION=${{ steps.tag.outputs.tag }}" >> $GITHUB_ENV
 
-      - name: Setup Python
-        uses: actions/setup-python@v4
+      - name: Setup pixi
+        uses: prefix-dev/setup-pixi@v0.9.1
         with:
-          python-version: "3.10"
+          pixi-version: v0.41.4
+          manifest-path: modflow6/pixi.toml
 
-      - name: Install Python dependencies
-        run: |
-          python -m pip install --upgrade pip
-          pip install -r requirements.txt
-          pip list
+      - name: Custom pixi install
+        working-directory: modflow6
+        run: pixi run install
 
       - name: Get OS tag
         id: ostag
         run: |
-          ostag=$(python -c "from modflow_devtools.ostags import get_ostag; print(get_ostag())")
+          ostag=$(pixi run --manifest-path modflow6/pixi.toml python -c "from modflow_devtools.ostags import get_ostag; print(get_ostag())")
           echo "ostag=$ostag" >> $GITHUB_OUTPUT
 
+      # interactive debugging
+      # - name: Setup tmate session
+      #   uses: mxschmitt/action-tmate@v3
+
       - name: Build programs
         uses: nick-fields/retry@v3
         with:
@@ -90,12 +96,12 @@ jobs:
           command: |
             ostag="${{ steps.ostag.outputs.ostag }}"
             mkdir $ostag
-            make-program : --appdir $ostag -ex gridgen --zip $ostag.zip --verbose
-            make-program mf2005,mflgr,mfnwt,mfusg --appdir $ostag --double --keep --zip $ostag.zip --verbose
+            pixi run --manifest-path modflow6/pixi.toml make-program : --appdir $ostag --exclude gridgen --zip $ostag.zip --verbose
+            pixi run --manifest-path modflow6/pixi.toml make-program mf2005,mflgr,mfnwt,mfusg --appdir $ostag --double --keep --zip $ostag.zip --verbose
             if [[ "${{ matrix.os }}" == "macos-14" ]]; then
-              make-program mf6 --appdir $ostag --keep --zip $ostag.zip --verbose --fflags='-O1'
+              pixi run --manifest-path modflow6/pixi.toml make-program mf6 --appdir $ostag --keep --zip $ostag.zip --verbose --fflags='-O1'
             fi
-            make-code-json --appdir $ostag --zip $ostag.zip --verbose
+            pixi run --manifest-path modflow6/pixi.toml make-code-json --appdir $ostag --zip $ostag.zip --verbose
 
       - name: Show programs
         run: |
@@ -194,8 +200,6 @@ jobs:
       # interactive debugging
       # - name: Setup tmate session
       #   uses: mxschmitt/action-tmate@v3
-      #   with:
-      #     limit-access-to-actor: true
 
       - name: Update readme
         id: update-readme
diff --git a/requirements.txt b/requirements.txt
deleted file mode 100644
index 1681eef..0000000
--- a/requirements.txt
+++ /dev/null
@@ -1,3 +0,0 @@
-wheel
-https://github.com/modflowpy/pymake/archive/develop.zip
-https://github.com/MODFLOW-ORG/modflow-devtools/archive/develop.zip
\ No newline at end of file