Sourdough Mountain Trail

Sourdough Mountain Trail is a long, hiker-only climb in North Cascades National Park up to the historic Sourdough Lookout. The trail runs steeply through forest, then transitions into subalpine meadows and finishes on rocky ridge terrain at the lookout site.

For the Diablo approach, the first stretch is especially relentless: through the first ~3.5 miles, you switchback upward through forest with little to no water. The grade eases later and the route reaches Sourdough Creek, where a designated camp sits at about 4.2 miles.

From the creek/camp zone, the final push is 1.5 miles or so of subalpine meadow and ridge-top travel to the lookout, with wide views over Diablo Lake far below and surrounding peaks and glaciers.

Backcountry camping is limited to designated camps along Sourdough Ridge (Sourdough Camp and Pierce Mountain Camp), with no camping at the lookout itself; a backcountry permit is required for overnight stays and permits are limited.

Dogs and other pets have tight restrictions in this area: leashed pets are only allowed within Ross Lake National Recreation Area, and pets are not allowed at either of the camps or at the lookout summit.

Route history is part of the destination. Sourdough Mountain was one of the first U.S. Forest Service “lookout” points established in 1915, with the present lookout building dating to 1933 and rehabilitated in 1998–99.

More information: Visitor information, Sourdough Mountain — Washington Trails Association, Sourdough Mountain