Fish Lake-Mountain Ash Cutoff Trail

Dogs No Dogs

Features River/Creek

Most runners (and horse parties) using this trail are headed to spectacular 250-foot Union Falls. But beware, the trailhead is one of the most difficult to reach in the Yellowstone trail system. Moreover, the two river fords should not be attempted before mid-July. Start southwest of Fish Lake, which is reached by a 1.5 mile high-clearance vehicle spur road on the north side of the Flagg-Ashton NFS Road (also called the Grassy Lake Road) about 18 gravel-road miles west of Flagg Ranch. First take the 1.2 mile Fish Lake-Mountain Ash Spur Trail which leads to our trail, the Fish Lake-Mountain Ash Cutoff Trail.

From the parking area southwest of Fish Lake, follow the Fish Lake-Mountain Ash Spur Trail 1.2 miles north to a trail junction, just inside Yellowstone NP. A trail to campsite 9C6 lies to the right. Turn left and continue another .2 miles to the next junction where the Mountain Ash Cutoff Trail splits off to the right and begins its 1.9 mile course to join the Mountain Ash Creek Trail.

The Cutoff Trail immediately fords the Falls River. Its a tricky, knee-to-thigh-deep ford even after the spring runoff subsides, usually by mid-July. Once across the river, the trail travels over rolling terrain and crosses knee-to-thigh-deep Mountain Ash Creek before joining the Mountain Ash Creek Trail.

From here, to the right, Union Falls lies just 5 miles away.

Thanks to guidebook author, Tom Carter, for sharing this trail description. To learn more about visiting Yellowstone, check out his book, Day Hiking Yellowstone.