Lake St. Clair is the critical link in the Great Lakes chain between Lake Huron and Lake Erie. The St. Clair River flows in from the north carrying Lake Huron water, while the Detroit River drains the lake south into Lake Erie. Additional inflows include the Thames River and Sydenham River from the Ontario side and the Clinton River from Michigan. The St. Clair Flats delta at the river's mouth is one of the largest freshwater deltas in the world.
Lake St. Clair's shallow 11-foot average depth means it can freeze in cold winters, and ice fishing for perch and walleye draws crowds. However, its connection to the Great Lakes system via the St. Clair and Detroit Rivers creates currents and unpredictable ice conditions — pressure ridges, thin spots, and shifting ice shelves are real dangers. Never venture out without checking current local ice reports.