page_title: Taum Sauk Hydroelectric Power Station
section_title: Reconstruction
hierarchical_section_title: Taum Sauk Hydroelectric Power Station / History / Reconstruction
caption_attribution_description: English: Aerial photo of Taum Sauk Resovoir under construction. Taken in 22 November 2009 from 5500MSL.
context_page_description: The Taum Sauk pumped storage plant is a power station in the St. Francois mountain region of Missouri, United States about 90 miles south of St. Louis near Lesterville, Missouri, in Reynolds County. It is operated by Ameren Missouri.
  The pumped-storage hydroelectric plant was constructed from 1960–1962 and was designed to help meet daytime peak electric power demand. It began operation in 1963. 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. At night, excess electricity on the power grid is used to pump water back to the mountaintop.
  The Taum Sauk plant is an open-loop pure pumped operation: unlike some other pumped storage sites, there is no natural primary flow into the upper reservoir available for generation. It is therefore a net consumer of electricity; the laws of thermodynamics dictate that more power is used to pump the water up the mountain than is generated when it comes down. However, the plant is still economical to operate because the upper reservoir is refilled at night, when the electrical generation system is running at low-cost baseline capacity.
context_section_description: Federal regulators approved Ameren's plan to rebuild the reservoir, and construction began in late 2007. The rebuilt structure is made entirely of roller-compacted concrete, unlike the earth-fill original. In addition to better fill-detection instrumentation, it incorporates a spillway rated to handle overflow equal to the maximum capacity of both pumping units and a video system to monitor the water level. The US$490 million cost of rebuilding the reservoir was covered partially by insurance. The utility was prohibited from billing customers to recoup any of the cost.
  Water was pumped into the rebuilt reservoir for the first time on February 27, 2010, and engineers monitored the response of the new structure as the water level was repeatedly raised and lowered. The final approval required from the FERC for “return to normal project operations” was received on April 1, 2010.  The utility met the Missouri Public Service Commission’s in-service criteria for operations on April 15, and electricity was first generated from the new structure on April 21, 2010. The new dam was recognized by the United States Society on Dams with its "Award of Excellence in the Constructed Project". On September 27, 2010, IEEE rededicated the plant as an IEEE Milestone.
caption: Aerial photo shows reconstruction progress in late November 2009
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