Diablo Dam is one of three arch dams along the upper Skagit River. It is the middle of the three dams on this part of the river in North Cascades National Park. It supplies Seattle with some of its power needs and is 389 feet tall. At the time Diablo Dam was built, in 1930, it was the tallest dam in the world. The roadway curves across the top of Diablo Dam, and you can actually drive across it when the gate is open.
Ian