Diablo Dam, Washington
Nestled in the North Cascade range along the upper Skagit River, Diablo Dam isn't the tallest (Mossyrock Dam), longest-operating (Monroe Street Dam) or most powerful (Grand Coulee Dam) hydroelectric dam in Washington. But when it comes to being enveloped by heavenly natural beauty, this 129-megawatt facility has its peers beat.
When completed in 1936, Diablo Dam — one of three National Register of Historic Places-listed facilities on the Skagit that provide Seattle with a decent chunk of its electricity needs — was the tallest dam in the world at 389 feet. (Today, that honor goes to China's 1,001-foot-tall Jinping-1 Dam). While dam construction has gone on to reach more dizzying heights, Diablo's Dam’s reservoir, Diablo Lake, has gotten no less beautiful. Located 1,200 feet above sea level, Diablo Lake, simply put, looks unreal. Traveling down the historic North Cascade Highway, the brilliant turquoise water of the reservoir is impossible to miss — it positively shines. (The crystalline lake's distinctive jade-green glow comes courtesy of finely ground glacier sentiment suspended in the water).
A hiking and kayaking hot spot during the summer months, the reservoir also can be traversed along the crest of the dam itself on a dizzying, lamppost-studded roadway. It's a short and somewhat panic-inducing drive but one of the most spectacular in the entire state. The dam's owner, Seattle City Light, also operates boat tours of the lake itself.