Lower Monumental Dam


Lower Monumental Lock and Dam is a hydroelectric, concrete, run-of-the-river dam in the northwest United States. Located on the Snake River, it bridges Franklin and Walla Walla counties in southeast Washington. It is south of Kahlotus and north of Walla Walla.
Construction began in June 1961, and 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 in length.
Lower Monumental Dam is part of the Columbia River Basin system of dams.
Behind the dam, Lake Herbert G. West is the reservoir; it extends east to the base of Little Goose Dam. Lake Sacajawea, formed from Ice Harbor Dam, runs southwest, downstream from the base of the dam.
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