​Mayfield Dam

Mayfield Dam is part of Tacoma Power’s Cowlitz River Project on the Cowlitz River in Lewis County. Completed in 1963, the dam is 250 feet high above bedrock and 850 feet long. The concrete arch and gravity dam can generate a maximum of 162 megawatts of clean, renewable hydropower, enough to supply more than 63,000 Northwest homes annually.

The dam created Mayfield Lake, a 2,250-acre reservoir fed by the Cowlitz and Tilton rivers. Mayfield Lake Park provides access to camping, boating, fishing and other outdoor recreation.

Tacoma Power stocks Mayfield Lake annually with rainbow trout, and the Washington Department of Fish and Wildlife stocks tiger muskies for recreational fishing.

For questions, please email Cowlitz@tacoma.gov.

At a Glance

• Dam type: Concrete arch-gravity and embankment
• Completed: 1963
• Height: 250 feet above bedrock
• Length: 850 feet
• Reservoir: Mayfield Lake
• River: Cowlitz River
• Powerhouse: Mayfield Powerhouse
• Generators: Four 40,500-kilowatt generators
• Installed capacity: 162,000 kilowatts