Mossyrock Dam
Mossyrock Dam is a concrete double-arch-gravity dam on the Cowlitz River near Mossyrock in Lewis County, Washington, United States. The reservoir created by the dam is called Riffe Lake. The primary purpose of the dam is hydroelectric production while flood control is a secondary function. The dam is the tallest in Washington state and its hydroelectric power station supplies 40% of Tacoma Power's electricity.
History
Planning for the Mossyrock Dam began in the 1940s but opposition from local fishers and Washington State's Fish and Wildlife Department delayed construction. During World War II, the city of Tacoma, Washington, purchased its electricity from the Bonneville Power Administration and from Seattle, with costs of up to $1 million/year. To generate its own electricity, Tacoma City Light built several dams, including the Mossyrock Dam. Plans for the Mossyrock Dam were announced in 1948 but met stiff opposition. The Washington State Legislature enacted a fish sanctuary on the Cowlitz River that initially blocked the project. Tacoma City sued, with its suit being raised to the Supreme Court of [the United States|US Supreme Court] a total of three times. After that, construction of the dam was approved. Construction began in 1965 and ended in 1968. On October 13, 1968, the dam's power plant generated its first electricity. Several towns were forced to evacuate ahead of the rising dam waters including Kosmos, Nesika, and Riffe.Tacoma City Light originally proposed naming the facility the "Homer T. Bone Dam", in honor of Senator Homer Bone of Tacoma.