Seneca Pumped Storage Project Powerhouse, Pennsylvania

image from pumped storage exhibit
The circular upper reservoir is a half-mile wide, and rests 800 feet above the power station next to the river.

The Seneca Pumped Storage project pumps water out of the Allegheny River, 800 feet up to a storage reservoir, mostly at night when electricity is cheaper and in less demand, then during the day lets the water flow back down through the same pipes through pump/turbines, that generate around 450 megawatts of electricity for the grid. The plant went online in 1970, and was built next to the preexisting Kinzua Dam, a large flood control dam made by the Army Corps of Engineers in the early 1960s, that backs up the river into a reservoir 24 miles long, flooding all the way to the Seneca Indian Reservation in New York State. The powerhouse is below the dam, and discharges water into the river at the stilling basin at the bottom of the dam, then flows down the Allegheny River unobstructed, all the way to Pittsburgh, 195 miles downstream. There are two pumped storage projects in Pennsylvania, and a few dozen in the USA. Seneca’s upper storage reservoir is unusual, as it is a circle, a half a mile in diameter.