1963,2010 442.4mw Taum Sauk Pumped Storage north of Lesterville, MO

Upper Reservoir: (Satellite)

Powerhouse: (Satellite)

Dam that Creates Lower Reservoir: (Satellite)

This is a view of the upper reservoir that was built on top of a mountain. When electric power is plentiful, water is pumped up the mountain into this reservoir. When extra power is needed, water flows back down into the lower reservoir to create hydropower.

ameren
"It began operation in 1963. The upper reservoir was rebuilt in 2010."

The upper reservoir was rebuilt in 2010 because a pump did not turn off when the reservoir was full, and it caused part of the dam to be washed out. I'll let Grady Hillhouse's video explain.

20:09 video @ 0:20

Civil Engineering Help posted four images with the comment:

The upper reservoir of the Taum Sauk plant.

The Taum Sauk pumped storage plant is a power station in the St. Francois mountain region of Missouri, United States about 90 miles (140 km) south of St. Louis near Lesterville, Missouri, in Reynolds County. It is operated by Ameren Missouri.

The rebuilt upper reservoir of the Taum Sauk plant is the largest roller-compacted concrete dam in North America.

The upper reservoir can hold about 1.5 billion U.S. gallons (4,600 acre feet; 5.7 million cubic meters) of water behind a wall nearly 100 feet (30 m) tall. It sits 760 feet (230 m) above the 450 MW hydroelectric plant, which gives it a greater head than that of Hoover Dam. The two are connected by a 7,000-foot (2,100 m) tunnel bored through the mountain.

The Taum Sauk upper reservoir sits atop Proffit Mountain, not Taum Sauk Mountain, which is about 5 miles (8.0 km) to the east. It is visible from Route 21 north of Centerville and from Route N approaching Johnson's Shut-ins State Park from the south.

Xavier Kaighin: That was an interesting project to be a part of. I calibrated the scales for the RCC and conventional concrete plants. Pretty wild they produced 7.5yds of RCC every 45 seconds.

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Mark Frazier: Check out that huge scar where the original structure failed and devastated Johnson Shut-ins State Park and Black River.

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