- Diablo Dam is one of three dams along the upper Skagit River in Whatcom County, Washington and part of the Skagit River Hydroelectric Project that supplies Seattle with some of its power needs. The dam was built in Diablo Canyon, a gorge of solid granite with vertical walls rising 160 feet (49 m) from the river bed, yet were less than 100 feet (30 m) apart. Construction began in 1927, and was completed in 1930. The dam began generating electricity in 1936.
