The Smith Mountain Dam was built on Roanoke River primarily to produce hydropower to offset the variable output of local Appalachian coal-fired power plants. The reservoir basin and dam was built starting in 1960, and the plant went online in 1966, with five turbines installed, producing a total output of as much as 560 megawatts. Three of the turbines are reversible, becoming pumps that move the water back from the lower reservoir (part of the river flooded by the Leesville Dam) to the upper reservoir, Smith Mountain Lake, the portion of the river impounded by the Smith Mountain Dam. The reservoir’s 32 square miles are now heavily developed with expensive lakeside properties, and maintaining steady shoreline levels of the hydropower reservoir has become a major concern.