Diablo Lake

Diablo Lake sits on the Skagit River inside Ross Lake National Recreation Area, part of the North Cascades National Park Service Complex. It is a reservoir. The National Park Service says Ross, Diablo, and Gorge lakes were created by dams of the Skagit Hydroelectric Project, operated by Seattle City Light. Diablo Lake runs about five miles from Diablo Dam to Ross Dam.

In summer the water turns a hard turquoise. NPS says the color comes from glacial flour — fine rock particles worn off the surrounding mountains by ice, then carried into the lake by glacial streams. The particles refract sunlight. The color is strongest on sunny days in July, August, and September, when seasonal melt is on.

State Route 20 reaches an overlook at mile 131.7. From there the lake, the surrounding peaks, and Diablo Dam are in view. The sources below are the National Park Service record of the lake and the park complex.