Santee National Wildlife Refuge is a 15,000-acre (61 km2) refuge alongside Lake Marion, an impoundment of the Santee River of Clarendon County, South Carolina. The refuge is especially important for a large number of wetlands that support migratory birds.The refuge also contains the Santee Native American mound, which is the farthest eastern known representation of the Mississippian culture. Later built upon this same mound was the Revolutionary British Fort Watson, which was taken by Marion's Brigade in April 1781. The site has been an important site of archeological investigations.