Bath County Pumped Storage Station is the United States largest pumped storage project, with a total installed capacity of 3003 megawatt (MW) through six units, generating electricity for residents spanning six states. The project, located in Bath County, Virginia, is owned jointly by Dominion Energy (60%) and Allegheny Power System (40%).

The project’s licence was issued in January, 1977, and commercial operation began in December, 1985.

The project consists of a 47Mm3 upper reservoir impounded by a 140m high, 671m-long central core earth and rock-fill dam and a 38Mm3 lower reservoir impounded by a 41m-high, 732m-long central core earth and rock-fill lower dam. The project has 365m of head.

The power tunnel and penstock system, connecting the upper and lower reservoirs via the powerhouse, is comprised of three power tunnels with a diameter of 8.7m and three 300m-high shafts. The tunnel/penstock system includes 7.2km of tunnels. Excavation of the powerhouse required removal of about 380,000m3 of rock, with rock cuts in the excavation ranging from 21 to 104m.

According to en.Wikipedia; Source of photo: internet