Lower Monumental Dam
|Lower Monumental Dam|
Lower Monumental Dam and the Snake River from the southwest, looking northeast, upstream.
|Location||Franklin / Walla Walla counties, Washington, USA|
|Construction began||June 1961|
|Operator(s)||U.S. Army Corps of Engineers|
|Dam and spillways|
|Type of dam||Concrete gravity, run-of-the-river|
|Height||100 feet (30 m)|
|Length||3,791 feet (1,155 m)|
|Spillway type||Service, gate-controlled|
|Creates||Lake Herbert G. West|
|Total capacity||432,000 acre·ft (0.533 km3)|
|Surface area||6,590 acres (26.7 km2)|
|Turbines||6 x 135-153 MW|
|Installed capacity||810 MW
932 MW (max)
Lower Monumental Lock and Dam is a hydroelectric, concrete, run-of-the-river dam on the Snake River, and bridges Franklin County and Walla Walla County, in the state of Washington. The dam is located six miles (10 km) south of the town of Kahlotus, and 43 miles (69 km) north of the town of Walla Walla.
Construction began in June 1961. The main structure and three generators were completed in 1969, with an additional three generators finished in 1981. Generating capacity is 810 megawatts, with an overload capacity of 932 MW. The spillway has eight gates and is 572 feet (176 m) long.
Lower Monumental Dam is part of the Columbia River Basin system of dams.
Lake Herbert G. West, which extends 28 miles (45 km) east to the base of Little Goose Dam, is formed behind the dam. Lake Sacajawea, formed from Ice Harbor Dam, runs 35 miles (56 km) southwest, downstream from the base of the dam.
- Navigation lock
- 86 feet (26 m) wide
- 666 feet (203 m) long
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