San Juan Mountains

Why go

What sets the San Juans apart is how high the public roads go, and that four towns sit at the bottom of them. The Forest Service describes the Alpine Loop as a 63-mile route that climbs to 12,800 feet, “crossing Engineer and Cinnamon Passes among five of Colorado’s spectacular ‘fourteeners’.” It calls Imogene “one of Colorado’s top 4WD routes,” a 13,114-foot pass linking two old mining towns, with the Tomboy mine and town site 3,000 feet above Telluride.

The BLM, which manages the loop, says driving all of it “is easily an all-day experience,” and that miles of designated side routes let you stretch a visit over several days. Along the way, in its words, are “old mines, ghost towns, and natural wonders.”

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When to go

Snow sets the calendar. Ouray County’s road and bridge crews seasonally open and maintain Yankee Boy, Red Mountain Town, Owl Creek Pass, Brown Mountain, Corkscrew Pass, Imogene Pass and Engineer Pass. They start clearing snow and debris in May, and the county says “every effort is made to open these roadways by July 4th,” working with San Miguel, San Juan and Hinsdale counties, the Forest Service and the BLM.

The Forest Service lists June as the season of use for Ophir Pass and July for Imogene and Black Bear, and says the Canyon Creek and Yankee Boy road is usually open by mid-June. The BLM gives the Alpine Loop’s best season simply as summer.

None of it is a promise. The county posts openings on its road and bridge department’s social media pages, and the offices listed at the end of this guide are the ones to ask.

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The main roads, by the BLM’s numbers

Start with the map in the BLM’s Alpine Loop brochure. It draws roads two ways: solid lines, open to all vehicles and marked “2WD Passable,” and dashed lines marked “4WD Recommended.” It also prints a table of distances and driving times.

The times say more than the mileages: 18 miles over Imogene takes four hours. Uphill traffic has the right of way, “but common courtesy works best,” and motor vehicles must stay on the designated routes the map shows. The map carries one warning of its own: Poughkeepsie Gulch is “for expert 4x4 drivers only. Winch strongly recommended.” The brochure tells anyone without that experience to use Engineer Pass instead.

To stay on pavement, take the San Juan Skyway, a 236-mile state byway through Durango, Silverton, Ouray and Telluride. The Colorado Department of Transportation calls the stretch from Ouray to Silverton the Million Dollar Highway.

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Imogene, Ophir and Black Bear

Three Forest Service roads link US 550 and Ouray with Telluride and Ophir. Ophir Pass Road is “generally an easy 4-wheel drive road,” rated moderate only for a narrow half-mile section on the Ophir side where two vehicles struggle to pass; downhill traffic yields to uphill there. It leaves US 550 about 4.2 miles north of Silverton.

Tomboy Road over Imogene Pass is open to all motor vehicles, but a high-clearance four-wheel drive is strongly recommended. From Telluride it climbs past the privately owned Tomboy townsite, crosses the pass and drops through Imogene Basin to Camp Bird Road above Ouray.

Black Bear Pass is “a very technical trail that is not for inexperienced drivers or riders.” It leaves US 550 just south of the Red Mountain Pass summit and reaches the 12,840-foot pass at 3.2 miles. At about mile 5.6 it starts down the Steps, a series of steep rock steps, then makes extremely tight switchbacks past Ingram Falls to the Bridal Veil powerplant.

Do not skipFrom the top of the Steps to the Bridal Veil powerplant, about one mile, Black Bear Pass Road is one-way, downhill only. The Forest Service strongly recommends a high-clearance, short-wheelbase four-wheel drive for that section.

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Camp Bird Road and Yankee Boy Basin

Camp Bird Road is County Road 361. It leaves US 550 at a bend about 0.3 miles south of Ouray, signed for Camp Bird Mine, Yankee Boy Basin and Box Canyon Falls. The Forest Service describes what follows: a graded dirt road that turns into a narrow shelf road blasted into the canyon’s west wall.

At mile 6, where Sneffels, Imogene and Canyon creeks meet, the left fork goes to the Camp Bird gold mine and Imogene Pass. The basin road narrows and follows Sneffels Creek past the site of Sneffels, a town founded in 1875. At mile 6.9 a left fork climbs toward Governor Basin. From there the road is rocky and climbs steeply for another mile or so into Yankee Boy Basin, above timberline under Mount Sneffels. There are vault toilets in the basin and no other services.

The vehicle advice is specific. Medium to high clearance is required to reach the basin. Four-wheel drive is recommended beyond it, where a steep, rough, rutted road that needs high clearance and low gears continues to the Mount Sneffels trailhead. Low-clearance passenger cars should not attempt the trip. Wildflowers are abundant from mid-July through early August, and weekends are crowded.

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What your vehicle needs, and the OHV permit

For the Alpine Loop the agencies agree. The BLM calls it a 4x4-only road, and the Forest Service says portions of it require high-clearance four-wheel-drive vehicles. Elsewhere the requirement changes road by road, as above.

Colorado adds a permit. Colorado Parks and Wildlife requires an OHV permit for “all plated, street legal vehicles (resident and nonresident) when traveling on any designated OHV trail and/or open area for recreational use on public lands,” and the BLM brochure repeats the rule. CPW lists the permit at $26.25 as of September 2026, valid April 1 through March 31 and displayed to the right of the front license plate. Ask CPW or the BLM which of the routes you plan to drive count as designated OHV trails.

Download or print maps before you leave town. The BLM says “cell phones and wireless devices do not work in most areas of the Alpine Loop.”

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Campgrounds

On the Ouray side the Forest Service lists three. Amphitheater, just south of town off US 550, is concession operated and reservations are recommended. Thistledown and Angel Creek are on Camp Bird Road, run by the Forest Service without reservations. Angel Creek is primitive: it requires a high-clearance vehicle and is not designed for trailers.

Near Silverton, South Mineral Campground has 26 first-come, first-served sites and drinking water, 4 miles up Forest Road 585 from US 550. The road is drivable in two-wheel drive as far as the campground and becomes four-wheel drive just past it. Dispersed camping along Forest Road 585 is allowed only in the designated Anvil, Bear and Sultan camping areas.

On the Lake City side, the BLM’s Mill Creek Campground sits on the Alpine Loop itself. It is covered in our guide to the loop.

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Dispersed camping and stay limits

Camping outside campgrounds is allowed on most of this land, under three sets of rules.

The BLM adds rules for the mining sites: do not camp, smoke or build campfires within 150 feet of historic buildings, and do not camp or build campfires within 800 feet of the Animas Forks historic site. Not all land along these roads is public. The brochure’s words are “respect private property.”

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Weather, fuel and who to call

The National Weather Service says thunderstorms typically develop in the Colorado mountains after 11 a.m., so plan to be heading down by late morning. An enclosed, metal-roofed vehicle is safe shelter from lightning. A tent is not. Wait 30 minutes after the last thunder before getting out.

Above timberline, the BLM warns, the air is thinner and colder, high winds are common and there is no shelter from sun, wind or precipitation. The Forest Service adds altitude sickness, “which can be life threatening,” for Yankee Boy Basin. Old mine workings are the other hazard. The BLM’s rule is “Stay Out, Stay Alive.”

The BLM map puts Ouray at 7,792 feet, Lake City at 8,671, Telluride at 8,750 and Silverton at 9,318. Plan fuel around the towns and confirm before you go; the brochure’s advice is to “know how far you are going and where to stop for gas.”

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Questions people ask