diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 4b7a9a94..ba7925a8 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -458,6 +458,7 @@ jobs:
     needs: [set-os, prepare-nonhindcast-cache]
     runs-on: ubuntu-latest
     strategy:
+      fail-fast: false
       matrix:
         module:
           [wave, tidal, river, dolfyn, power, loads, mooring, acoustics, utils]
@@ -478,15 +479,17 @@ jobs:
           path: ~/.cache/mhkit
 
       - name: Install system dependencies
+        if: matrix.module != 'river' || matrix.module != 'power' || matrix.module != 'utils' || matrix.module != 'loads'
         run: sudo apt-get install -y libhdf5-dev libnetcdf-dev
 
       - name: Install MHKiT with optional dependency
         run: |
           python -m pip install --upgrade pip
-          pip install "mhkit[${{ matrix.module }}]"
+          pip install -e ".[${{ matrix.module }}]"
           pip install pytest
 
       - name: Reinstall h5py and netCDF4 with system libraries
+        if: matrix.module != 'river' || matrix.module != 'power' || matrix.module != 'utils' || matrix.module != 'loads'
         run: "pip install --force-reinstall --no-binary=:all: h5py netCDF4"
 
       - name: Run tests for ${{ matrix.module }}
diff --git a/mhkit/wave/__init__.py b/mhkit/wave/__init__.py
index f84c667c..7fbaf30b 100644
--- a/mhkit/wave/__init__.py
+++ b/mhkit/wave/__init__.py
@@ -1,5 +1,37 @@
+import importlib
+
 from mhkit.wave import resource
-from mhkit.wave import io
 from mhkit.wave import graphics
 from mhkit.wave import performance
 from mhkit.wave import contours
+
+
+def __getattr__(name):
+    """
+    Lazy load the wave.io submodule using PEP 562 module-level __getattr__.
+
+    This defers importing heavy wave.io dependencies (rex, netCDF4, etc,) until
+    they are actually accessed, improving import time for users who don't need
+    all wave submodules, and avoiding import errors for users who have specified
+    module level installs that need wave module functions, but not wave.io functions.
+    """
+    if name == "io":
+        # This uses importlib.import_module() here, not "from mhkit.wave import io"
+        # because when Python executes getattr(), it looks for 'io' as an attribute of
+        # mhkit.wave. At this point in the module loading code 'io' doesn't exist yet and
+        # Python calls __getattr__('io') again. This triggers the same "from" statement,
+        # which calls __getattr__('io') again yielding a RecursionError.
+        #
+        # To fix this uses importlib.import_module("mhkit.wave.io") which loads the module directly
+        # using the  absolute path without doing attribute lookup on the parent.
+        #
+        # The statement "from mhkit.wave import io" is equivalent to:
+        #   io = getattr(mhkit.wave, 'io')
+        #
+        io = importlib.import_module("mhkit.wave.io")
+
+        # Cache the module so subsequent accesses bypass __getattr__ entirely
+        globals()[name] = io
+        return io
+
+    raise AttributeError(f"module '{__name__}' has no attribute '{name}'")
diff --git a/pyproject.toml b/pyproject.toml
index 7623b9ed..c0c7df26 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -27,6 +27,7 @@ dependencies = [
     "xarray>=2024.6.0",
     "matplotlib>=3.9.1",
     "pecos>=0.3.0",
+    "requests",
 ]
 
 [project.optional-dependencies]
@@ -38,20 +39,17 @@ wave = [
     "pytz",
     "NREL-rex>=0.2.63",
     "beautifulsoup4",
-    "requests",
     "bottleneck",
     "lxml"
 ]
 
 tidal = [
     "netCDF4>=1.7.1.post1",
-    "requests",
     "bottleneck"
 ]
 
 river = [
     "netCDF4>=1.7.1.post1",
-    "requests",
     "bottleneck",
 ]
 
@@ -66,7 +64,9 @@ power = [
 ]
 
 loads = [
- "fatpack"
+    "fatpack",
+    "statsmodels>=0.14.2",
+    "scikit-learn>=1.5.1",
 ]
 
 mooring = [