Cowlitz River Project

Tacoma Power's largest electricity generating facility is the Cowlitz River Project. About 2 billion kilowatt-hours of renewable, hydroelectric energy is produced each year, enough energy to serve over 135,000 Northwest homes.

The Cowlitz River Project produces hydroelectric power from the water stored behind Mayfield and Mossyrock dams. Built in 1963, Mayfield Dam forms 13-mile-long Mayfield Lake. Mossyrock Dam, built in 1968, stands 606 feet above bedrock and is the tallest dam is Washington State. The dam forms 23.5-mile-long Riffe Lake.

In addition to producing hydro electric power, the Cowlitz River Project provides outstanding recreational opportunities, nearly 14,000 acres of lands managed for wildlife habitat and a fisheries program involving two major hatcheries.

Enjoy camping, boating or fishing? Click on the links to Tacoma Power's Mossyrock, Taidnapam, and Mayfield Lake Parks. These lakefront parks feature facilities for RV, group and tent camping as well as picnic areas and boat ramps.

Tacoma Power’s Cowlitz Salmon Hatchery and Cowlitz Trout Hatchery rear Coho salmon, Chinook salmon, steelhead, and cutthroat trout.  Wild adult fish are collected at the salmon hatchery barrier dam and trucked up stream above the dams.  Out-migrating juvenile fish are collected and either hauled or diverted around the dams.

The 14,000-acre Cowlitz Wildlife Area, which surrounds Mayfield and Riffe Lakes, is managed and enhanced for a variety of birds and animals including deer, elk, wood duck, osprey and bald eagle. The Washington Department of Fish and Wildlife manages the wildlife land for Tacoma Power.

A new license for operating Cowlitz River Project was issued in 2002. The emphasis of the new license is the restoration and recovery of wild salmon runs in the Cowlitz River.

Take a Tour

One of the most popular community activities sponsored by Tacoma Power is the Mossyrock Dam Open House held every May. People take in the view from the top of the state's tallest dam, see interesting displays and exhibits and enjoy the camaraderie of Tacoma Power employees who volunteer their time to host the open house.

Free group tours of Cowlitz River Project facilities are available for school, civic, business and recreational groups during regular working hours by appointment. To make arrangements for a tour, call Tacoma Power at 253-502-8759.

Enjoy your visit!

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