North Fork of the Big Wood River
Enjoy rugged scenery and quiet solitude in the Boulder Mountains near Sun Valley.
- Location: Boulder-White Clouds
- Status: Proposed Wilderness
- Distance: 9 miles round trip
- Elevation: 1,200 ft
- Difficulty: Moderate
- Maps: Sawtooth National Forest, SNRA, Ketchum & Fairfield District; USGS Ryan Peak, Amber Lakes
- More information: Day Hiking Near Sun Valley
At the east end of the parking lot is a trailhead sign for the North Fork Trail and West Pass Creek. Begin your hike here. At about a half mile, the trail is rerouted to an area that takes you away from the stream. Stay on the main trail at the horse detour signs; do not take the lower horse trail.
As you make your way north up the river valley, you can see open areas and wooded sections. At 1.5 miles, wade across a tributary, which flows from the West Pass drainage. After you cross, hike another eighth of a mile to the trail junction for the West Pass. The junction is marked by a trail sign that says, “Upper No. Fork Tr. #128." Continue straight on the main trail.
At 4.5 miles, you can see an old sheepherder’s camp near the river. Beyond the camp, three streams come together in a heavily wooded area. Note: Only expert hikers should cross-country hike in the upper North Fork.
Directions
From Ketchum, drive north on Highway 75 for 8 miles until you reach the main building of the Sawtooth National Recreation Area. Take a right on North Fork Road and continue past the parking area for 5 miles. The road ends in a parking area by the river. Begin your hike here.

