The Clinton River, located just north of the city of Detroit, flows approximately 80 miles from its headwaters to Lake St. Clair, near the city of Mount Clemens. The Clinton River Area of Concern encompasses the entire Clinton River watershed. The boundaries include the Clinton River and its tributaries, as well as the spillway and nearshore area of Lake St. Clair between the mouth of the Clinton River and the spillway. The watershed drains approximately 760 square miles of southeastern Michigan. Although historical industrial and municipal discharges were the primary causes of water quality degradation in the Clinton River Area of Concern, ongoing contamination problems are almost exclusively of nonpoint source origin.