Lake Vernon Trail

Lake Vernon is a 19.1-mile out-and-back from Hetch Hetchy Trailhead at O’Shaughnessy Dam. Cross the dam, climb through Beehive Meadow and rolling woodland, then reach a high-country lake backed by an exposed granite ridge. Allow about 10 hours of hiking; it’s a full-day effort for the lake and the quiet country beyond the reservoir.

This is a long, strenuous route, not a quick lake walk. Hetch Hetchy Road is open only in daylight and the gate closes at sunset, so leave enough time to return. The trailhead is reached by car, and the lot can fill around midday on weekends. Overnight camping requires a wilderness permit; dogs aren’t allowed on the dam or hiking trails.

The first climb gains the valley rim on open, dusty switchbacks. Look back for views over Hetch Hetchy Reservoir and O’Shaughnessy Dam. Higher up, the route settles into rolling, wooded hills before the terrain opens onto broad granite. Summers can be hot on the lower approach, so don’t count on small streams for all your water.

Lake Vernon sits beside a bare granite ridge, with the shore and outlet area as the payoff after the long approach. The tread can be harder to follow across broad granite near the lake; keep checking the route instead of wandering onto a different line. Jack Main Canyon and Tiltill Valley continue beyond the lake, but this row is the Lake Vernon out-and-back, so turn around here.

The walk begins beside O’Shaughnessy Dam, built in stages in the 1920s and 1930s to create a reservoir that now supplies drinking water to the Bay Area. The damming of Hetch Hetchy was a major conservation fight: the Raker Act authorized the project in 1913, while John Muir argued to preserve the valley. On the lower slopes, gray pine, incense-cedar, black oak and manzanita are part of the Hetch Hetchy landscape; spring and early summer bring lupine and other wildflowers.