inland waterway 538 miles (866 km) long, in the southeastern United States, rising as the Catawba River in the Blue Ridge Mountains of western North Carolina. The Catawba flows east and then south into South Carolina to Great Falls, a distance of 220 miles (350 km), where it becomes the Wateree River. The Wateree continues southward through a series of lakes and reservoirs, the largest being Wateree Lake (15 miles 【24 km】 long), to its junction with the Congaree (Congaree River). From this confluence the Santee, as it is called, winds southeastward for 143 miles (230 km) to its delta on the Atlantic Ocean south of Georgetown, S.C. The Santee has been dammed to form Lake Marion, a reservoir 40 miles (64 km) long that is connected by a navigable waterway, Lake Moultrie, and by the Cooper River to Charleston, S.C.

The entire river system, navigable upstream as far as Camden, S.C., is the most important waterway and source of hydroelectric power in South Carolina.