Cabin Creek Power Plant, Colorado

Cabin Creek is one of a few dozen pumped storage hydro projects in the USA, and one of two major ones in Colorado. It is located in a steep valley south of Georgetown, at an elevation of more than 10,000 feet. It consists of similarly sized upper and lower reservoirs, separated by 1,192 feet of elevation, and a power plant on the shore of the lower reservoir. Water goes up and down between the reservoirs through a 3/4-mile-long underground tunnel, and through two reversible pump turbines, capable of generating 324 megawatts between them. The plant opened in 1967, and is owned by Xcel Energy, a large regional utility company that operates facilities in the midwest and west, including a dozen coal-fired plants and two nuclear plants. The plant might be best known for a tragic industrial accident in 2007. Workers were doing repairs inside the main tunnel, spraying epoxy sealant on the walls, when volatile solvents caught fire. With limited egress along the 4,125-foot-long underground tube, some workers were trapped inside. Five of them died.