The first section of trail #835 runs north from the Sourdough Trailhead and climbs gently, sometimes on old roads. It gains 1,000' in this first three miles past Fourmile Creek and is fairly level for the next two miles. It climbs a couple switchbacks to the trail's highest point along the 10,200' contour. The Sourdough Trail dips down, passing the Little Raven Trail and on to the Red Rock Trailhead.
From the Brainard Lake Road, the trail continues to drop elevation by about 500' in two miles. It crosses South Saint Vrain Creek on a wide bridge, and intersects with the South Saint Vrain Trail #909 on the other side. The Sourdough Trail drops to cross National Forest System Road 113, and continues on to Beaver Reservoir. The trail continues on the other side of the Beaver Reservoir Road. It then joins with Buchanan Pass Trail near Camp Dick Campground.
Directions: From Nederland, travel seven miles north on Colorado Highway 72. Turn west onto National Forest System Road 298, signed as the turnoff for the University of Colorado Mountain Research Station. A parking area is not far on the left. Three other trailheads serve Sourdough Trail: Red Rock Trailhead, Beaver Reservoir Trailhead, and Middle Saint Vrain Trailhead.
Day Hiking: The Sourdough Trail climbs over ridges and crosses creeks along the eastern flanks of the Continental Divide. It is a long-distance trail with multiple access points that facilitate moderate out-and-back trips, end-to-end shuttle trips and multiple side-loop opportunities. This trail intersects Little Raven Trail, South Saint Vrain Trail, Beaver Reservoir Cutoff, and Buchanan Pass Trail.
Permit Info: No permits are required at this time.
Restrictions: Motorized vehicles prohibited.
Closest Towns: Nederland and Ward, Colorado
Water: Occasional streams; treat water for drinking.
Restroom: Vault toilets at Sourdough Trailhead and near Middle St. Vrain Trailhead at Camp Dick
Elevation: 9,200' - 10,200'
Information Center: Boulder Ranger District, 2140 Yarmouth Ave, Boulder, CO 80301, Phone 303-541-2500, Fax 303-541-2515