Taum Sauk Hydroelectric Power Station

Taum Sauk Hydroelectric Power Station

The Taum Sauk pumped storage plant is located in the St. Francois mountain region of the Missouri Ozarks approximately 90 miles (140 km) south of St. Louis near Lesterville, Missouri in Reynolds County. The pumped-storage hydroelectric plant, operated by the AmerenUE electric company, was designed to help meet peak power demands during the day. Electrical generators are turned by water flowing from a reservoir on top of Proffit Mountain into a lower reservoir on the East Fork of the Black River. The generators and turbines at river level are reversible, and at night the excess electricity available on the power grid is used to pump water back to the mountaintop.

The Taum Sauk plant is notable in that it is a pure pump-back operation – there is no natural primary flow available for generation, unlike most other pumped storage sites. It was among the largest such projects when it was built. Construction of the Taum Sauk plant began in 1960 and operation began in 1963. The two original reversible pump-turbine units were each capable of generating 175 megawatts of power. They were upgraded in 1999 to units capable of 225 megawatts each.

The plant was out of operation after the upper reservoir suffered a catastrophic failure on December 14, 2005, until the rebuilt and recertified structure started producing power again on April 21, 2010. The new upper reservoir dam, rebuilt from the ground up, is the largest roller-compacted concrete dam in North America. The plant was named an IEEE Milestone in 2005.