North Cascades National Park

Sourdough Mountain Trail

Sourdough Mountain Trail is a steep and strenuous day hike or an overnight backpack. The trail gains 5100 feet in 5.2 miles (1550 m in 8.4 km) with superb views from an historic fire lookout.

The Sourdough Mountain Trail begins behind the domed swimming pool in the town of Diablo, at milepost 126 off State Route 20. The Pierce Mountain route begins 2.5 miles (4 km) from the Ross Dam Trailhead (milepost 134, State Route 20) on Big Beaver Trail.

Diablo Approach
In the first 3.5 miles (5.6 km), hikers switchback through shady forest. Use caution in crossing Sourdough Creek. Efforts are grandly rewarded in the last 1.5 miles (2.4 km) of subalpine meadow and ridge top. Wildflowers, birds, small mammals, deer, and black bear thrive there. Views from the summit are spectacular ... peaks and valleys in all directions. Blue lakes, grand glaciers, and the volcanic dome of Mount Baker highlight the display.

Pierce Mountain Approach
This route is longer (8.3 miles or 13.4 km) and less steep. The lower trail follows Ross Lake. The upper trail ascends through Douglas-fir and mountain hemlock forest zones, before breaking into subalpine meadows. Hikers pass through a recent burn area (1978) overgrown with lush grasses. Follow rock cairns along the ridge to Sourdough Lookout.

Sourdough Lookout
A historic landmark, the summit of Sourdough was one of the first "lookout" points established by the U.S. Forest Service in 1915. Glee Davis built the original lookout in 1917. The present building dating to 1933, was rehabilitated in 1998-99. "Bush" Osborne chose the location to test his fire locating device. The Osborne Firefinder soon became standard equipment in lookouts. Note: Sourdough Lookout is closed to the public.

Camping is available in two designated camps along Sourdough Ridge. Sourdough Camp is 4.2 miles (6.8 km) from Diablo trailhead and Pierce Mountain Camp is 0.5 mile (0.8 km) NE of the lookout. Bring a stove. Fires are not permitted in the fragile subalpine areas of the National Park.

Be sure to stop by the Wilderness Information Center in Marblemount (360-873-4500 ext. 39). A permit (no charge) is required for all overnight stays in the backcountry. Pets and firearms are prohibited in the National Park; however, hunting is permitted in Ross Lake National Recreation Area. Washington State hunting and fishing regulations apply. Rangers have maps and current information to assist you in planning a safe, fun trip.




For Additional Information Contact:

North Cascades National Park
2105 State Route 20
Sedro-Woolley, WA 98284-9394
(360) 856-5700


For more information visit the National Park Service website