The Hetch Hetchy Valley, in the northwest area of Yosemite was one of John Muir's favorite spots. When the O'Shaughnessy Dam was built on the Tuolumne River in the 1920's, the valley was flooded. This created the Hetch Hetchy Reservoir which is eight miles long and the largest single body of water in Yosemite. The reservoir is a water supply for communities west of Yosemite including San Francisco.
The valley has an iconic rock formation called Kolana Rock, and Wapama Falls which flows year-round, yet relatively few people visit this area of the park. So, even with park visitation up, it is possible to see this beautiful area without another person in sight.
Start Your Hike at O'Shaughnessy Dam
The dam is accessible by car but be aware that the road is only open from 7:00 am to 7:00 pm.
Enter Yosemite at the Big Oak Flat Entrance from Highway 120 (Groveland). Shortly after entering the park, take a right on Evergreen Road which takes you to the beautiful Evergreen Lodge area. This resort is on 22 acres with cabins and camping options. (www.evergreenlodge.com)
Evergreen Road turns into Hetch Hetchy Road and ends at the dam's parking lot 25.6 miles from the park entrance.
Watch Wapama Falls plummet 1,400 feet over granite cliffs. You can see the waterfall from the dam, but the easy trail hike to the waterfall's base is worth spectacular view.
To begin the trail, cross the dam and pass through the tunnel. The trail is 2.5-mile one way along the shore of the reservoir and has footbridges at the base of the double falls.
In springtime when the flow is at its peak, the water from this fall sometimes flows over the footbridges so be prepared to get splashed. More plusses in spring - you will pass two smaller waterfalls on the way and see a lot of wildflowers.
Kolana Rock is the large granite dome towering 2,000 feet over the edge of the reservoir.
"The most strikingly picturesque rock in Hetch Hetchy Valley is a majestic pyramid over 2,000 feet in height which is called by the Indians 'Kolana.' It is the outermost of a group like the Cathedral Rocks of Yosemite and occupies the same relative position on the south wall." - John Muir
When standing at Wapama Falls, pivot to view the Kolana Rock across the water. (This rock is also visible from the dam, looking to your right.)
For Longer Hike, Continue to Racheria Falls
The trail to Rancheria Falls continues past Wapama Fall and may be done as either a long day hike (13 miles round trip) or a backpacking trip. Along the way, hikers will see beautiful views of the valley and waterfalls. Backpackers can access Tiltill or Rancheria mountains and the vast northwest wilderness of Yosemite from the Rancheria area.
Carry plenty of water and sunscreen and watch for rattlesnakes and poison oak. Overnight backpackers need a wilderness permit, which can be obtained at the Hetch Hetchy Entrance Station at no cost. Bear canisters are required for backcountry food storage for overnight hikers.