Blackhawk Co. Trail
Blackhawk Co. Trail (FR 501) is a long, high-alpine hiking route in the San Juan National Forest that follows the Colorado Trail corridor as an out-and-back between Forest Road 578 (near Celebration Lake / Bolam Pass Road / Hermosa Park Road) and Forest Road 550 (Hotel Draw Road). The trail length is about 25.8 miles round trip and it runs from roughly 10,392 ft up to 11,995 ft. Expect strenuous climbing driven largely by elevation and sustained high-country tread.
The route is managed for non-motorized use, and it’s also open to horseback riding and trail running, along with hiking/backpacking. The mapped trail is designated as a ground-surface path and is marked as bicycle-permitted in the route data, but for hikers the main reality is that this is a remote, high-elevation day hike or overnight backpacking mission.
Elevation and grade are the governing factors: it is described as a high-alpine trail running between about 12,000 ft and about 10,200 ft for much of its length, with an overall elevation gain around 4,409 ft. Plan on a hard effort even if you’re strong on distance, because the route spends a lot of time at altitude rather than just making a single big push.
Trail terrain connects to classic Colorado Trail segment 26 landings—turning up from the Celebration Lake area, then climbing toward a junction with the old Circle Trail and a saddle, before reaching the end near Hotel Draw Road. Farther south, the Blackhawk Trail connects with the Highline Trail, so you’ll see intersection traffic if you’re continuing beyond the out-and-back.
Blackhawk Trail #501 is intended for hikers who can handle rugged high-country conditions. There’s access constraint on both ends: reach points via FS 578 (Bolam Pass Road) should be by high-clearance vehicles, and the same kind of access guidance applies at the other end (FS 550 / Hotel Draw Road).
Backcountry overnight is possible along the route, and there are no overnight permits required for San Juan National Forest use. Dispersed camping is allowed under applicable regulations, but the trail runs in an area where conditions can shift quickly, so you’ll want to be equipped for snow, hail, wind, and afternoon thunderstorms that can build rapidly in the San Juan Mountains.