diff --git a/README.md b/README.md
index 23706c4f..9c2dad64 100644
--- a/README.md
+++ b/README.md
@@ -43,11 +43,10 @@ Python development tools for MODFLOW 6 and related projects.
 
 Python3.10+, dependency-free by default.
 
-Several optional dependency groups are available, oriented around specific use cases:
+Two main dependency groups are available, oriented around specific use cases:
 
-- `dfn`: MF6 definition file parsing
-- `test`: pytest fixtures/extensions
-- `models`: example model access
+- `test`: pytest fixtures, markers, and extensions
+- `ecosystem`: program/model management, definition file utilities
 
 ## Installation
 
diff --git a/pyproject.toml b/pyproject.toml
index 0b26a6b3..57fdafc6 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -69,11 +69,13 @@ docs = [
     "sphinx-rtd-theme",
     "myst-parser"
 ]
+# deprecated
 dfn = [
     "boltons",
     "tomli",
     "tomli-w"
 ]
+# deprecated
 models = [
     "boltons",
     "filelock",
@@ -82,6 +84,8 @@ models = [
     "tomli",
     "tomli-w"
 ]
+# prefer ecosystem to dfn/models separately
+ecosystem = ["modflow-devtools[dfn,models]"]
 dev = ["modflow-devtools[lint,test,docs,dfn,models]"]
 
 [dependency-groups]
@@ -115,11 +119,13 @@ docs = [
     "sphinx-rtd-theme",
     "myst-parser"
 ]
+# deprecated
 dfn = [
     "boltons",
     "tomli",
     "tomli-w"
 ]
+# deprecated
 models = [
     "boltons",
     "filelock",
@@ -128,6 +134,11 @@ models = [
     "tomli",
     "tomli-w"
 ]
+# prefer ecosystem to dfn/models separately
+ecosystem = [
+    {include-group = "dfn"},
+    {include-group = "models"},
+]
 dev = [
     {include-group = "build"},
     {include-group = "lint"},