There is a Yosemite Valley most visitors never see. It sits at the same elevation as the famous one, runs roughly the same length, was carved by the same kind of glacier into the same kind of granite, and was, by John Muir's own description, "one of nature's rarest and most precious mountain temples." It is also currently underwater. Or about half of it is, anyway, beneath a reservoir that supplies drinking water to roughly 2.7 million people in the San Francisco Bay Area.
Hetch Hetchy is the Yosemite Valley you skipped. The story of how it ended up under a reservoir is one of the founding tragedies of the American conservation movement, and the place you can visit today is, even with the dam, one of the most rewarding parts of the entire park.
It is also the most underused major destination in Yosemite. On a Saturday in July when the Valley is bumper-to-bumper at the entrance station, you can drive into Hetch Hetchy in the morning, cross the dam, hike five miles to one of the great waterfalls in the Sierra, and see fewer than a hundred people the entire day.
This is how to do that, and what to think about while you're doing it.
Hetch Hetchy sits in the northwestern corner of Yosemite National Park, accessed via Highway 120 to the Big Oak Flat Entrance and then a separate road that branches north before you reach the Valley. The drive from the Big Oak Flat Entrance to the O'Shaughnessy Dam (the trailhead for almost everything you'll do here) is about 16 miles, with significant winding mountain road. From Yosemite Valley, you're looking at roughly an hour and forty-five minutes of driving each way.
The valley itself is about 8 miles long and a half-mile wide on average. Before the dam, it had a meadow floor at about 3,800 feet, two major waterfalls (Wapama and Tueeulala, the latter only running in spring snowmelt) on its north wall, and a forested rim with significant stands of black oak, ponderosa pine, and incense cedar. Today, the lower portion of the valley is filled with the Hetch Hetchy Reservoir, which holds 117 billion gallons of water at full capacity.
The dam was completed in 1923. The reservoir filled in the years after. The valley floor that John Muir walked is, depending on the water level in any given year, somewhere between 200 and 350 feet underwater.
The short version, because it's worth knowing.
In the early 1900s, the city of San Francisco was looking for a reliable, gravity-fed water source. The 1906 earthquake and the fires that followed had exposed the limits of the city's existing water system. Engineers had identified Hetch Hetchy as a near-ideal reservoir site for decades. The valley had hard granite walls, a narrow outlet, an upstream watershed of high-elevation snow, and was outside the more visible Yosemite Valley.
The catch was that Hetch Hetchy was inside the boundaries of Yosemite National Park, which had been federally protected since 1890.
San Francisco applied for the water rights anyway. The fight that followed lasted from roughly 1908 through 1913. On one side were the city, much of California, and a coalition of utilitarian conservationists who believed that the highest use of natural resources was supplying human needs. On the other side were John Muir, the newly-formed Sierra Club, and a small group of preservationist conservationists who believed that some places should be protected from human use because of what they were, not because of what they could provide.
Muir was the public face of the resistance. He was 75 years old when the fight began. He wrote some of the most ferocious prose of his career on Hetch Hetchy, calling the proposed dam "a cult of ravaging commercialism" and describing the supporters of the project as "temple destroyers, devotees of ravaging commercialism, who seem to have a perfect contempt for Nature, and instead of lifting their eyes to the God of the mountains, lift them to the Almighty Dollar."
He lost. The Raker Act passed Congress in 1913. President Wilson signed it. Construction on the dam began in 1914. Muir died in late 1914, partly of pneumonia and, his biographers and his friends both said, partly of the heartbreak of losing this fight.
The Sierra Club, which Muir co-founded in 1892, has not stopped trying to get the dam removed in the century since.
The version of Hetch Hetchy you can visit is the version above the waterline plus the reservoir surface. It is still extraordinary.
The two major waterfalls on the valley's north wall are largely above the reservoir. Wapama Falls drops over 1,000 feet down the cliff just east of the dam, splitting into multiple cascades in lower portions, and is one of the great waterfalls in the Sierra. It runs reliably from spring through midsummer, and in high-water years it produces enough spray that the bridge crossing its base becomes a wet experience and is sometimes closed for safety. The bridge has actually been swept out by debris in flood years.
Tueeulala Falls, just west of Wapama, is a wispier spring-only waterfall that runs in May and June and is gone by July most years. The combination of Wapama and Tueeulala in spring is the best version of Hetch Hetchy you can see.
The granite walls rising from the reservoir are largely intact above the water level. Hetch Hetchy Dome on the north side, Kolana Rock on the south, and the Tueeulala-Wapama-Hetch Hetchy Falls drainage system all show the same kind of glacial sculpting as the major features in Yosemite Valley. If you took a photo of Kolana Rock and put it next to a photo of Cathedral Rocks in Yosemite Valley, most people would not be able to tell which valley each one was in.
This is the part of the loss that's hard to convey to anyone who hasn't been here. Hetch Hetchy is not a sad fragment of a lost valley. It is a real place, geologically and ecologically of the same family as Yosemite Valley, and the sense you get standing on the dam looking east into the reservoir is not "this used to be something." It is "this still is something, and it is connected to a thing that was destroyed but isn't entirely lost."
The valley's wildlife is still here. Black bears use the trails. Mule deer wade in the meadows above the high-water line in spring. Pacific tree frogs, ringtails, and bobcats are documented residents. Bald eagles have nested on cliff ledges above the reservoir. The bird life is unusually rich because of the water and the relatively low visitor pressure.
Hetch Hetchy works as a single full-day trip from anywhere in the park. It does not work as a half-day add-on, because of the drive in and out.
The dam itself. O'Shaughnessy Dam is open to foot traffic. The walk across the dam is a quarter mile and takes you through a hand-cut tunnel into the valley proper. It's flat, paved, and one of the few non-hiker-accessible ways to stand inside a Sierra granite valley. From the middle of the dam, you can see the reservoir extending east toward Wapama Falls and the upper valley. The dam was built in two phases (1923 and 1938), and the seam between the two construction periods is visible from the upstream side. There are interpretive signs at the eastern end of the dam.
Wapama Falls trail. The standard out-and-back hike from the dam to the base of Wapama Falls and back is about 5 miles round trip, with roughly 700 feet of cumulative elevation gain (mostly from rolling terrain rather than a big climb). The trail is well-maintained, partly shaded, and crosses several footbridges. The terminal bridge at the base of Wapama can be wet and is sometimes closed in high-flow conditions; check the NPS conditions page before you go in May or June.
This is the standard Hetch Hetchy day. It is doable for most reasonably fit visitors, scenic the entire way, and ends at the base of one of the great waterfalls in the park. Plan four to five hours including time at the falls. Bring water and food. Sun protection matters; the trail is exposed in many sections.
Rancheria Falls trail. The longer extension to the next major fall east. The full hike to Rancheria Falls and back is about 13 miles round trip, with significant cumulative elevation gain. Rancheria is less dramatic than Wapama but the trail beyond Wapama is significantly less used and gives you the flavor of the upper valley. This is a real day hike. Most visitors don't do it.
Lake Eleanor and Smith Peak. Longer trips into the higher country above Hetch Hetchy. Lake Eleanor, north of the reservoir, is reachable by a multi-mile trail that gets very little traffic. Smith Peak, at over 7,700 feet, is a non-trivial climb but offers a unique view down into Hetch Hetchy from above. These are full-day or backpacking trips, not casual day hikes.
Kayaking. It is technically not allowed on the reservoir itself. Hetch Hetchy is a domestic water supply, and recreational use of the water is restricted by SFPUC regulations. Boating, swimming, and fishing in the reservoir are not permitted, except in narrow circumstances with specific permits.
The road into Hetch Hetchy is open from sunrise to sunset most days, with the exact hours posted at the entrance station. This is a real constraint. If you arrive at 7 p.m. in July expecting to see the dam at sunset, you'll be denied entry. Plan your day around the gate hours. The hours change seasonally and are posted on the NPS Hetch Hetchy page.
The road also has a 25-foot vehicle length restriction. Large RVs and trailered boats are not allowed. There is no overnight camping at the trailhead area, though the Hetch Hetchy Backpackers Campground is available with a wilderness permit for overnight wilderness trips.
The drive itself is windy. The last several miles into the dam area include hairpin turns and steep drops. Don't speed. Don't pass.
Hetch Hetchy is best in spring and early summer, roughly April through June. The waterfalls are running, the temperatures at this lower elevation are pleasant, and the wildflower display in the upper valley above the trail can be impressive.
By July, Tueeulala is gone and Wapama is reduced. By August, Wapama is a much smaller column and the lower-elevation trails are hot. The valley reaches into the 90s on summer afternoons. By September, much of the standard summer scenery is gone.
October has its own appeal. The black oaks in the valley turn gold. The crowds, which were never significant, are essentially absent. The reservoir reflects the autumn light off the granite walls in a way that's particular to the season.
Winter is closed in some senses (snow can close the access road) but is also a real option in low-snow years or after road clearing. Hetch Hetchy in February in a clearing-storm window, with snow capping the upper rim and the lower elevations dry, is one of the photographic experiences in the park. Check road conditions before you drive up.
A short list, in order of importance.
It's far from the Valley. The drive in and out is most of a day for many visitors. People who came to see Yosemite Valley don't budget the time.
It's not on the marketing materials. The big tour operators don't run Hetch Hetchy trips. The standard "Yosemite in a day" tours skip it. Most guidebooks treat it as an optional side trip rather than a main destination.
It's misunderstood. Many visitors who hear about Hetch Hetchy understand it as a reservoir, not as a valley. The image they have is of a body of water with a dam, and they don't understand that what they'd actually be visiting is one of the great glacial valleys in North America with two significant waterfalls and trails along its rim.
It has fewer amenities. No food. No lodging in the immediate area. Limited bathrooms. The road has hours. Visitors used to the convenience of Yosemite Valley find Hetch Hetchy a different mode.
These are exactly the reasons it stays uncrowded. They are also the reasons it is one of the best parts of the park to visit.
A short list of things that, if you let them, will deepen the visit.
The water you're seeing is going to San Francisco. The reservoir feeds the Hetch Hetchy Aqueduct, a 167-mile gravity-fed system that delivers water to the Bay Area without significant pumping. The water is renowned for its quality. Some 85% of the city's water supply originates here. The system also generates hydroelectric power. Whatever you think of the dam, this is what it does, and millions of people drink from it every day.
The valley below the waterline is still there. The granite floor, the meadows that were once flooded, the old trail systems, the original riverbed of the Tuolumne River. None of that was removed. It is preserved underwater, in a kind of geological cold storage, and if the dam were ever removed (a long-running advocacy goal of the Sierra Club and others), the valley would emerge. The U.S. Department of the Interior's 2006 study concluded that draining and restoring Hetch Hetchy was technically feasible. The political and infrastructural obstacles are significant. Whether it will happen in the next century is unknown.
Muir was right and Muir was wrong. Muir's argument was that the valley was sacred and irreplaceable, and that no amount of utilitarian benefit could justify its destruction. The dam supporters' argument was that providing reliable water and power to a major American city was a higher use than preserving a place for a smaller number of visitors. Both arguments contained truth. The fight became the founding template for almost every conservation battle of the twentieth century, and the philosophical positions Muir staked out, even in losing, became the foundation of the National Park idea as it's now understood. The Sierra Club still uses Hetch Hetchy as the touchstone for the principle that some places should be protected as ends in themselves, not as means.
The valley is healing. Above the high-water line, the ecology of Hetch Hetchy is essentially intact. Black bears, mountain lions, peregrine falcons, and the full Sierra mid-elevation forest community are all present and stable. The valley's role as wildlife habitat may, in some respects, have been improved by the lower visitation. This is not an excuse for the dam. It is also not nothing.
Hetch Hetchy is closer to a reasonable day's drive than most visitors realize, has waterfalls that match anything in Yosemite Valley in spring, and is one of the few places in the park where you can experience a Sierra granite valley with hardly anyone else around. The dam is a fact. The dam is also, depending on your view, a tragedy or a necessity. The valley above the dam is still doing the work of being itself.
Drive up early, walk to Wapama, eat lunch at the base of the falls, walk back. Stand on the dam for a moment on the way out and look east into the reservoir. Picture the meadow that's down there. Then notice the granite, the falls, the eagles overhead, the valley you can see.
That's the trip.