Afternoon storm risk is the line that matters. Everything else is comfort. In summer, plan to be off the ridge before the build-up starts, not as it starts. Forecast for the summit point, adjusted for its elevation · data from Open-Meteo.
Alternate route · West Slope
Overview
The West Slope of Snowmass Mountain starts in Lead King Basin and climbs a big gully up the mountain's west face. You hike past Geneva Lake and Little Gem Lake, cross a stream, and then scramble up a loose slope of ribs and gullies to a narrow summit ridge.
This is a Class 3 route. It is not the standard route, and the upper slope is full of large, loose rock. Even big blocks can shift. The final ridge is narrow with a big drop on the east side. It suits experienced scramblers who are careful on unstable ground. The trip is about 9 miles with about 4,500 feet of gain.
Plan on 8 to 11 hours car to car. Many people camp near Geneva Lake to break it up.
Plan of the day
Start by
By 4 or 5 a.m. from the trailhead, or at first light from a camp at Geneva Lake.
Turnaround
If you are not at the base of the slope near 12,400 feet by about 8 a.m., or storms are building, turn back. The loose upper slope is slow and hard to leave in a hurry.
Crux
The loose rock in the main gully above the grassy patch, and the narrow, exposed summit ridge.
Route-finding
Moderate to hard. Trails are good to Little Gem Lake. On the face, find the grassy patch near the cliffs above the pale talus and use it to find the main gully, which splits the center of the face.
Water
Plenty along the approach, including Geneva Lake, Little Gem Lake and the stream below the face. None on the upper slope. Filter all water.
From Carbondale, drive about 21.5 miles south on Colorado 133. Turn left on County Road 3 toward Marble. After about 5.5 miles you reach the middle of Marble; continue through town. The road gets rough at about 7 miles.
At about 7.7 miles, turn left on Forest Road 315 toward Lead King Basin. The last 6 or more miles are rough and narrow and need a four-wheel-drive vehicle. Stay left at a junction at about 9.7 miles. The road switchbacks many times and crosses a small stream near 13.8 miles; a second creek crossing a little farther on brings you to the trailhead. The trail leaves from the parking area's east side.
Trail in the treesTundraTalus and screeRidgeExposed to lightning
The line is elevation, the band underneath is the ground, and the numbered dots match the steps below. Mileage and elevations are approximate.
1
Lead King Basin trailhead 9,700' · 0 mi
Begin on the good trail at the east edge of the parking area.
2
Trail junction 9,800' · 0.4 mi
Keep left, following the Geneva Lake trail. It goes through brush and swings left up the hillside.
3
Above the waterfall 10,700' · 1.3 mi
The trail crosses a slope above a waterfall near 10,700 feet. It then goes through a bit of forest and past a small pond.
4
Geneva Lake 11,000' · 1.9 mi
Reach Geneva Lake. There are numbered campsites and side trails here. Turn left toward campsite 4 and head north.
Watch for: Good place to filter water.
5
Meadow north of the lake 11,200' · 2.3 mi
Walk through an open area at the lake's north end, over a small hill, through trees and into a big meadow. Follow the trail across it and up another slope.
6
Little Gem Lake 11,700' · 2.9 mi
Reach Little Gem Lake near 11,700 feet. Pass the lake and keep going about a quarter mile.
7
Stream below the face 11,600' · 3.3 mi
Turn east and drop a little to the stream that feeds Geneva Lake. Study the face as you go. Look for a grassy patch near the cliffs above the pale talus. It marks the main gully.
8
Base of the slope 12,400' · 3.6 mi
Cross the stream and climb to the bottom of the face near 12,400 feet. Head toward the grassy patch.
Watch for: Put on your helmet here.
9
Main gully 12,800' · 3.8 mi
Climb past the grass onto harder ground. Near 12,800 feet, go right briefly, then back left. Stay in the gully or along its left side as you climb.
Watch for: Rocks of all sizes move here. Test everything and keep your party close together.
10
Summit ridge in view 13,500' · 4.1 mi
Above 13,500 feet the summit ridge is right above you. Climb toward it. The big rocks get a little steadier around 13,800 feet.
11
Summit ridge 14,000' · 4.35 mi
Gain the narrow ridge above 14,000 feet and turn right.
Watch for: Big exposure on the left (east) side.
12
Summit of Snowmass Mountain 14,105' · 4.5 mi
Carefully follow the ridge. Drop a little to the right to go around several big rocks, then get back on the crest. Scramble up the summit rock.
Getting down
Go back the way you came. Descend the ridge with care, then drop back into the main gully. Go slowly on the loose rock and keep your group close so rocks knocked loose cannot pick up speed. Watch for the right-then-left jog near 12,800 feet and the grassy patch below it. From the stream, return past Little Gem Lake and Geneva Lake to the trailhead.
If things go wrong
Below the face, you can turn back at any time on good trails. On the face, the only real way off is back down the gully, which is slow. If a storm comes in, head down right away and do not wait on the ridge. Call 911 if someone is hurt. Help is far away and the road in is rough.
Other routes
Every way up Snowmass Mountain we list, with its class.
This describes the route in its usual season. Distances and elevations are close estimates for planning. Snow, ice, rockfall, a washed-out road or an afternoon storm can make it a very different climb. Check recent conditions the week you go and turn around when the day tells you to.
