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greenBlue O'Shaughnessy Dam Viewpoint


1.0 mile 1.7 kilometer point to point
85% Runnable


Ascent: 70' 21 m
Descent: -313' -95 m
High: 3,814' 1,163 m
Low: 3,501' 1,067 m


Avg Grade: 7% (4°)
Max Grade: 13% (8°)


No Dogs
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Trail shared by Megan W

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

Megan W

Features River/Creek · Views · Wildflowers

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… 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.

Runner Notes

The trail is relatively free from obstacles, making it a good run out to the viewpoint.


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 runners 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 running. 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

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Trail Ratings

  2.7 from 3 votes


in Hetch Hetchy


  2.7 from 3 votes
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33 Views Last Month
455 Since May 17, 2016
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