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If you'd like to inspect the dam that created the Hetch Hetchy Reservoir, this is your trail.

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Point to Point

3,814' 1,163 m


3,501' 1,067 m


70' 21 m


313' 95 m



Avg Grade (4°)


Max Grade (8°)

Dogs No Dogs

Features River/Creek · Views · Wildflowers

Family Friendly A short trail with a small climb, the kids will be impressed by the dam, and it is a great opportunity to learn about the history of the Hetch Hetchy Reservoir.

The Hetch Hetchy Road is open from 7 am to sunset throughout the year. The road may be closed or under chain restriction depending on the weather. You can check road conditions at nps.gov/yose/planyourvisit/… or by dialing 1-209-372-0200, dialing extensions 1/1. Overnight backpackers are required to have wilderness permits, which can be acquired from the park service or at the entrance station.


The trailhead for the O'Shaughnessy Dam Viewpoint trail is located at the bottom of the parking lot before you reach the dam. A gate blocks the road from traffic, but it is open to hikers and fishermen. After ducking under the gate, the trail descends steadily as it runs parallel to the the Tuolumne River, which runs below the trail on the right hand side. Wildflowers can be seen along the right side of the trail in the spring. The trail is a doubletrack gravel road, which makes for easy hiking. Around .4 miles, the trail cuts back to the right and makes its way to the river. At .5 mile, a road to the dam breaks off to the right. Even though there are no signs, park rangers and dam workers will ask you to turn back to prevent you from getting too close to the dam.

The trail continues straight ahead and is relatively exposed, so make sure to wear sunscreen and a hat. At roughly 3/4 of a mile, a wooden bridge crosses the Tuolumne River, offering great views of the river as it makes its way downstream. In the spring, the water moves swiftly while later in the summer, it meanders at a more relaxed pace. Curving around a small hill, the trail passes a tunnel goes into the hillside. This tunnel is part of the dam infrastructure and provides relief if the water levels are too high. After passing through a turnaround, the trail narrows to a singletrack dirt trail that leads out to a rock bench that provides sweeping views of the dam, surrounding hills, and the Tuolumne River as it makes its way downstream. The best views of the dam are along the rock bench. Wildflowers bloom in the fields in the spring, and fisherman can continue down to the river for great fishing. Once you have taken in the views, you return to your car via the trail you descended.

Due to the fact the trail is not marked at the trailhead, doesn't show up on any park maps, and is not listed in any of the park materials, you'll probably be the only person on the trail. You might run into a park ranger or dam worker in a vehicle, but that's about it. This trail provides an opportunity to see the dam from downstream and see the Tuolumne River as it resumes its course downstream. It also gives you an idea of how the dam has altered the surrounding landscape.

Flora & Fauna

Wildflowers bloom along the trail in the spring time. Deer, rabbits, lizards, and snakes can be seen along the trail.


Land Manager: NPS - Yosemite

Shared By:

Megan W

Trail Ratings

  2.7 from 3 votes


in Hetch Hetchy


  2.7 from 3 votes
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3 Views Last Month
1,018 Since May 17, 2016



View from the trail
May 3, 2023 near Yosemit…, CA
The Hetch Hetchy Reservoir from the start of the trail.
May 24, 2016 near Yosemit…, CA
A view of the Tuolumne River as it makes its way below the dam in the spring as water was being released.
May 24, 2016 near Yosemit…, CA
During a water release in the spring, the Tuolumne River roars downstream.
May 24, 2016 near Tuolumn…, CA
The trail as it enters an open field. Flowers bloom in the spring, and dam workers and rangers can be find resting here.
May 24, 2016 near Tuolumn…, CA
Looking down into the river valley below the dam.
May 24, 2016 near Yosemit…, CA



Current Trail Conditions

Add Your Check-In


Dec 29, 2017
James Moon
Sep 22, 2017
Blair Tirpak
Jul 24, 2017
Tess Paredes
May 21, 2016
David Hitchcock
Easy out and back hike, with views of the Dam and Tuolumne River. Wildflowers in bloom. 2.3mi