Four Mile Creek bottomland restoration program. Final report

On the Savannah River Site (SRS), nuclear production reactors were cooled by a once-through cooling cycle, using water from the Savannah River and discharging the effluent to small tributaries of the Savannah River. Four Mile Creek (also known as Fourmile Branch) is a third order tributary of the Savannah River on the upper coastal plain of South Carolina. It received thermal effluent from C Reactor from 1955 to 1985, which increased the flow rate, water depth and water temperature. Prior to 1955, the base flow was approximately one cubic meter per second, but increased, with the reactor effluent, to approximately 11 cubic meters per second, raising the water depth in the channel by 15 to 30 cm. Effluent temperature at the outfall was approximately 60 C and at the delta was 40 to 45 C, depending on the operation level of the reactor, the season of the year and the specific meteorological conditions. The increased flow rate also increased erosion in the upper reaches of the stream with deposition of this eroded material occurring in the delta averaging 60 cm of newly deposited sand on top of the former substrate