diff --git a/modflow_devtools/models/__init__.py b/modflow_devtools/models/__init__.py
index c9a00d7..6cd0891 100644
--- a/modflow_devtools/models/__init__.py
+++ b/modflow_devtools/models/__init__.py
@@ -52,7 +52,6 @@
     ".bud",  # budget file
     ".ddn",  # drawdown file
     ".ucn",  # concentration file
-    ".obs",  # observation file
     ".glo",  # global listing file
 ]
 """Output file extensions to exclude from model input registry"""