Lake St. Clair is a kettle lake with no outlet. It is fed by ground water and some runoff from Eaton Creek to the South.
It is located in the Nisqually Basin, approximately four miles west of the main stem river channel and about six river miles from the mouth.
The groundwater system is hydraulically connected to McAllister Springs and McAllister Creek to the north. The groundwater contributing area is approximately 40 square miles and enters the lake from the south and the west deep below the surface of the lake.
Unique and amazing geological mechanisms provide the enormous amounts of groundwater to Lake St Clair from below the ground surface. Read details in the reports below.