The first time you see Diablo Lake from the overlook on State Route 20, you will probably assume someone has tinted the photo. The water is an intense, milky turquoise, and it sits in a deep valley ringed by steep, forested slopes and jagged peaks streaked with snow and ice. The colour comes from glacial flour, fine rock dust ground by the glaciers above and carried down by streams. It reflects green and blue light, giving the lake its extraordinary hue.
Diablo Lake is a reservoir, one of three created by Seattle City Light on the Skagit River in the early twentieth century to provide hydroelectric power for the city. Ross Dam, Diablo Dam and Gorge Dam are still producing power, and the company town of Newhalem, a short distance west, was built to house workers. The Skagit valley here is remote and rugged, and building the dams and the road was a huge undertaking. The highway across the mountains was not completed until 1972.
The ride along this section of SR 20 is superb. The road climbs steadily from Newhalem through dense forest of cedar and hemlock, with tunnels cut through the rock and views of the Skagit River gorge below. The curves are long and flowing, with good asphalt and little traffic outside the summer months. After Diablo Lake, the road continues to climb, with views of Ross Lake and the peaks of the North Cascades National Park.
The North Cascades are one of the wildest mountain ranges in the United States, with more than three hundred glaciers and some of the most rugged terrain in the country. The national park sees far fewer visitors than Mount Rainier or Olympic, and much of it is accessible only on foot. Black bears, mountain goats and even the occasional grizzly or wolf live in these mountains.
There are very few services along this stretch. Newhalem has a small general store, and there are campgrounds along the river, but fuel is not available until you reach Marblemount to the west or Mazama to the east, both long distances away. The highway is closed in winter between Ross Lake and Mazama, usually from November to April. Check conditions before you set out, and fill your tank before entering the mountains.