is a civil township of St. Clair County in the U.S. state of Michigan. As of the 2000 census, the township population was 9,822. The township includes the inhabited Harsens Island.
According to the United States Census Bureau, the township has a total area of 82.5 square miles (213.7 km²), of which, 35.5 square miles (91.8 km²) of it is land and 47.1 square miles (121.9 km²) of it (57.03%) is water.
The township includes Harsens Island, Russell Island, Dickinson Island and St. Johns Marsh.