Two small reservoirs created by Seattle City Light dams on the upper Skagit River are Gorge Lake, covering 210 acres, and Diablo Lake, covering 910 acres; both are accessible from Highway 20. Diablo and Gorge Lakes get their emerald-green color from fine sediments in the glacial runoff.

The Gorge Powerhouse observation lobby (8 a.m.–4 p.m. daily May–Sept.) is accessed by a cable suspension footbridge. Continue beyond the power plant to Ladder Creek Falls and Rock Gardens. The colorful flower gardens were first planted here in the 1920s and create a delightful setting for the adjacent falls. At night both are lit up.

A mile off Highway 20 is the tiny company town of Diablo, the home of Diablo Powerplant and the Skagit Tour Center. A half dozen free campsites (no potable water) are available at nearby Gorge Lake Campground, and a popular (but very steep) five-mile trail leads from here to the 5,985-foot summit of Sourdough Mountain. Hikers are treated to lush alpine meadows and panoramic views.