The A Trail is 81 miles long and runs from a trailhead east of Alpine along the Greys River, almost to the Tri Basin Divide and then along the Smiths Fork River to the Smiths Fork Trailhead. For this mapping project it has been divided into three sections – Alpine to the Blind Bull Trail, Blind Bull Trail to Poison Creek Meadows and Smiths Fork Trailhead to Poison Creek Meadows (Smiths Fork Trail).
The northern section of the A Trail runs along the Greys River Road from a trail head in Alpine 25 miles to the east end of the Blind Bull Trail
Avalanche Hazards: The primary avalanche hazard to this trail during unstable conditions is from the Higgins Slide Path. This active path is located on the north side of the trail 5.2 miles east of the Alpine Trailhead and 2.1 miles west of the junction of the Greys River with the Little Greys River (A & D Trail Junction). This path is comprised of several gullies in a south-facing hillside that slide frequently (13 times during the 2007/08 season). If a trail user were caught in this slide they would likely be swept into the Greys River. A large avalanche in this area could include this entire slope. Several other slidepaths and numerous hillsides and banks exist in the stretch of trail from the bridge over the Greys River 1.6 miles east of the trailhead in Alpine to the junction of the A and D Trails.
The section of this trail from the Little Greys River to the east end of the Blind Bull Trail is threatened by one hillside that is 5.5 miles south of the Little Greys or 0.8 miles north of the junction of the south end of the C trail and the A trail.
The C Trail provides an alternate route to the Greys River Road (A Trail) from Squaw Creek to Murphy Creek. It is 12.4 miles long.
Avalanche Hazards: The section of this trail that is 0.5 to 1.8 miles south of its junction with the A Trail at Squaw Creek (10.6 to 11.9 miles south of its junction with the A Trail at Murphy Creek) passes through the run out zones of some large active avalanche paths to the west and across some steep banks to the east.
At 0.5 and 0.6 miles south of the A Trail Junction at Squaw Creek the trail crosses beneath two large active avalanche paths. Debris from these slide paths can hit the trail with significant force. Avalanches in these paths originate from an elevation of 6,800 feet that face northeast. The runout zones of other large avalanche paths originating from east facing starting zones at elevations of 7,500 to 8,400 feet are crossed at 0.9, 1.0 and 1.5 miles south of this junction. From 1.5 to 1.8 miles south of this junction there is a steep bank on the east side of the trail which could slide across the trail and into terrain traps with a creek.
The Little Greys River (D) Trail is 18 miles long. It runs from the intersection of the Greys and the Little Greys Rivers up the Little Greys River to McCain Meadow.
Avalanche Hazards: The primary avalanche hazard to this trail during unstable conditions are from steep hillsides located on the north and west side of the trail. A steep hillside 0.1 miles north of the junction of the Little Greys and Greys River Trails on the west side of the trail has some potential to slide to the trail during unstable conditions. At 0.4 miles north of this junction several large avalanches paths on the west side of the trail have the potential to run to the trail if a very large avalanche occurred. A steep hillside on the north side of the trail 2.8 to 3.2 miles from the junction has some potential to slide across the trail into the Little Greys River. Another steep gullied hillside exists above the north side of the trail and the river at mile 3.4. Steep hillsides above the river that also have some potential to slide under unstable conditions exist at miles 5.0, 6.3, 6.7, 7.6, 9.4 and 11.6. At several of these locations the potential exist for these hillsides to slide into the river. A steep bank on the north side of the trail 0.4 miles from the junction of this trail with iself also poses some hazard during unstable conditions.