South Holston Dam is a hydroelectric and flood control dam on the South Fork Holston River in Sullivan County, in the U.S. state of Tennessee. It is the uppermost of three dams on the South Fork Holston owned and operated by the Tennessee Valley Authority, which built the dam in the 1940s as part of efforts to control flooding in the Tennessee River watershed. On October 21, 1950 the valve gate closed and water began backing up to create South Holston Reservoir. Work began on the dam in December 1941, but in November 1942, the War Production Board requested that the operation be suspended because of a shortage of critical materials. Work did not resume until July 1, 1947. The dam now impounds the South Holston Lake of 7,550 acres (3,060 ha), which extends northeastward across the Tennessee