The Cooper River Basin (hydrologic units 03050201 and 03050202) is located in Charleston, Dorchester, and Berkeley Counties and encompasses 9 watersheds and 1,545 square miles. The Cooper River Basin incorporates the Lower Coastal Plain and Coastal Zone regions. Of approximately one million acres in the Cooper River Basin, 35.5% is forested land, 25.8% is forested wetland, 13.5% is urban land, 10.0% is water, 8.0% is nonforested wetland, 6.6% is agricultural land, and 0.6% is barren land. The urban land is comprised chiefly of the greater City of Charleston area. There are a total of 2,037.2 stream miles in the Cooper River Basin, together with 60,829.1 acres of lake waters, and 29,134.6 acres of estuarine areas.
The diverted Santee River flows into Lake Moultrie, out of Lake Moultrie's Pinopolis Dam, along the Tailrace Canal, and joins with Biggin Creek to form the West Branch Cooper River. The West Branch Cooper River then converges with the East Branch Cooper River at "The Tee" to form the Cooper River. The Cooper River then accepts drainage from the Back River, Goose Creek, the Wando River, and the Ashley River before flowing into Charleston Harbor and the Atlantic Ocean.
For an overview of water quality in the Cooper River Basin, download the Cooper water quality assessment summary. For specific basin descriptions, facts, figures, and detailed maps click on a watershed below: