diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 4f4a77a..9c40e0b 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ['3.6', '3.7', '3.8', '3.9', '3.10', '3.11', '3.12']
+        python-version: ['3.9', '3.10', '3.11', '3.12']
 
     steps:
     - name: Checkout repository
diff --git a/pyproject.toml b/pyproject.toml
index 9273ccf..7e8a74d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -8,19 +8,19 @@ version = "2.4.1"
 description = "A global hydrologic modeling framework"
 readme = "README.md"
 readme-content-type = "text/markdown"
-requires-python = ">=3.7"
+requires-python = ">=3.9"
 license = {file = "LICENSE"}
 authors = [
     { name = "Chris R. Vernon", email = "chris.vernon@pnnl.gov" }
 ]
 urls = { "Homepage" = "https://github.com/JGCRI/xanthos", "Repository" = "https://github.com/JGCRI/xanthos", "Documentation" = "https://github.com/JGCRI/xanthos/wiki" }
 dependencies = [
-    "numpy>=1.19.3,<2",
+    "numpy>=1.24.4",
     "scipy>=1.6",
     "pandas>=2.0.3",
     "configobj>=5.0.8",
     "joblib>=1.3.2",
-    "matplotlib>=3.5.3",
+    "matplotlib>=3.7.2",
     "xarray>=2023.8.0",
     "requests"
 ]