Bunker Hill Road to Slumgullion Earthflow — Gunnison Gorge Rim to Blue Mesa via Curecanti Backcountry
Deep San Juan canyon to a forgotten wilderness rim.
Forest Road 858 follows the North Fork of the Cimarron River into a deep canyon cut between 13,000-foot peaks of the Uncompahgre Wilderness — and most people blow right past the turnoff on US-50 without a second glance. That’s their loss. The road climbs alongside the river through aspen and spruce, past Silver Jack Reservoir (a legitimate high-country camp spot with a real boat ramp and good fishing), before the canyon walls tighten up and the road starts earning its keep near Courthouse Mountain and Chimney Rock — two of the most dramatic spires in the San Juans. The upper reaches at Owl Creek Pass connect to the Cimarron backcountry, with views down into the Uncompahgre Gorge that most tourists never see. Roughly 20 miles one-way from US-50 to Owl Creek Pass summit at 10,114 feet.
A stock 4WD with decent clearance handles the lower section fine; the upper stretch to Owl Creek Pass gets rougher and narrower with some shelf road exposure that’ll test wider rigs. Best from late June through September — the road above Silver Jack stays snowed in well into summer some years. Check with Gunnison Ranger District before heading up late or early season. No permit needed. Dispersed camping along the lower canyon is excellent and free. Nearest fuel is Montrose or Gunnison. Zero cell service above Silver Jack.
Trail Specs
| Difficulty | Moderate |
|---|---|
| Trail Type | Backcountry, High Clearance, Scenic Drive |
| Surface | Dirt, Gravel |
| Features | Camping, High Altitude, Remote, Scenic, Water Crossings |
| Length (miles) | 20 mi / 32.2 km |
| Duration | 1 day |
| Max elevation (ft) | 10114 ft |
| Best season | June-September |
| Minimum vehicle | Stock 4WD high-clearance |
| Nearest town | Montrose, CO |
| Land manager | USDA Forest Service – Gunnison National Forest, Gunnison Ranger District |
| Permit required | No |
| Cell service | None |
| Water crossings | Yes |
| Dispersed camping | Yes |
| Official sources | GMUG National Forest – Cimarron Area Gunnison-Uncompahgre NF main page |
| Start coordinates | |
| End coordinates | |
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Location
Trail Conditions
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Frequently asked questions
Can a stock 4Runner or Jeep Wrangler handle Bunker Hill Road to Slumgullion Earthflow without modifications?
A stock 4WD high-clearance rig like a 4Runner, Wrangler, or Tacoma is the minimum — this isn't the place for a lifted Subaru or stock crossover. The dirt and gravel surface is manageable, but ruts, loose rock, and water crossing approaches can catch low-slung vehicles off guard. Lockers are not required but are a comfort on wet or muddy sections.
When does this trail open for the season and is snow a real concern?
June through September is the reliable window — at 10,114 feet max elevation, snow lingers into late May and can return by October. Don't count on early June access without checking road conditions with the Gunnison Ranger District first; the upper sections hold snow and mud long after lower roads dry out.
Do I need a permit or pass to run this trail through Gunnison National Forest?
No permit is required to drive the trail or camp dispersed on Gunnison National Forest land. Standard dispersed camping rules apply — 14-day stay limit, 300 feet from water sources and roads. If you're crossing into Curecanti National Recreation Area boundary zones, check NPS regulations as rules can differ.
What's the hardest section and what should I actually be ready for?
The most committing section is the descent toward the Gunnison Gorge rim — loose rock, off-camber shelf road, and exposure with minimal room to turn around if you second-guess it. There are no bailout points mid-route, so if conditions go sideways, you're committed. Aired-down tires and a spotter for tight shelf sections are smart moves.
Is there any water available on trail, and how far is the nearest gas from the trailhead?
There are water crossings on this route but treat or filter everything — no potable water sources exist on trail. Montrose is your last reliable fuel stop, roughly 30-40 miles from the starting area, so top off before you head out — this is a one-tank-minimum commitment with zero services in between.
Trail track
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