diff --git a/python/ngen_cal/src/ngen/cal/ngen.py b/python/ngen_cal/src/ngen/cal/ngen.py
index 68822bcb..27c7db13 100644
--- a/python/ngen_cal/src/ngen/cal/ngen.py
+++ b/python/ngen_cal/src/ngen/cal/ngen.py
@@ -134,9 +134,12 @@ def __init__(self, **kwargs):
 
     def _register_default_ngen_plugins(self):
         from .ngen_hooks.ngen_output import TrouteOutput
+        from .ngen_hooks.observations import UsgsObservations
 
         # t-route outputs
         self._plugin_manager.register(TrouteOutput(self.routing_output))
+        # observations
+        self._plugin_manager.register(UsgsObservations())
 
     @staticmethod
     def _is_legacy_gpkg_hydrofabric(hydrofabric: Path) -> bool: