Hetch Hetchy Reservoir is located in the northwestern corner of Yosemite National Park and supplies drinking water to residents of the San Francisco Bay area. The reservoir is contained by the massive 430-foot O’Shaughnessy Dam, which was built in the 1920s along the main stem of the Tuolumne River. This Wild and Scenic River has its headwaters in the eastern Sierras and meanders across the serene Tuolumne Meadows in Yosemite National Park. It then tumbles through the Grand Canyon of the Tuolumne River and enters the Hetch Hetchy Reservoir.
The building of the O’Shaughnessy Dam and the subsequent flooding of the Hetch Hetchy Valley was a matter of great controversy in the early part of the 20th century. The Great 1906 San Francisco Earthquake and resulting fire highlighted the flaws in the city’s water systems. The quake remains one of the most significant earthquakes in history and sparked the search for a more adequate water system. The Hetch Hetchy Valley was identified as the perfect place for a reservoir for a number of reasons, primarily that the geology of the glacier-carved valley lent itself to the creation of a lake and there was little development and private ownership in the area. The biggest caveat perhaps was that the valley fell within the boundaries of Yosemite National Park which had been established as a national park in 1890. Park status not withstanding, Congress- and President Woodrow Wilson- authorized the construction of the dam in 1913.
Over the next 20 years, work on the dam went on continuously. In 1934, water from Hetch Hetchy was delivered to the residents of San Francisco. Today, the 360360 acre-foot capacity dam supplies water to over 2.5 million residents in the city and county of San Francisco. The clear waters of the Tuolumne River require minimal treatment before flowing through the faucets of Bay Area homes and businesses. In addition to clean water, the two hydroelectric plants downstream supply electricity to residents. That said, even with those benefits, nearly a century later there are still discussions regarding the environmental impacts of the dam and the flooding of the Hetch Hetchy Valley. It is doubtful whether the few environmental groups who are actively lobbying to have the reservoir drained and the valley restored will be successful in the near future. The prolonged periods of drought throughout California and insufficient water infrastructure at time of writing make it unlikely. In addition, there are green energy initiatives calling for an increase in renewable energy production, so taking away two hydroelectric generating plants would also likely not happen.
However, the purpose of this post is not to go into the politics surrounding the construction of reservoirs, even while remaining mindful of the environmental impacts. Hetch Hetchy is absolutely beautiful, and while it is one of the least visited areas of the park, it is definitely worth a drive. Evergreen Road off highway 120 terminates at the entrance to the national park and becomes Hetch Hetchy Road. It is the only road in this section of the park and connects to the trailheads, backpackers campground, and the parking area near the dam.
We traveled from Dimond O to O’Shaughnessy Dam the morning after our arrival at the campground. The total drive time was under 25 minutes, and most of that was because I observed the 25 mph speed limit once we entered the park. In addition to protecting wildlife and fellow visitors, the area is so pretty it deserves to be enjoyed rather than rushed through. Once we parked, we walked over to the dam and explored. From the dam, we could see Tueeulala and Wapama Falls. While enjoying the scenery, Sami and I talked about the ecology of the area, as well as the history of the dam and its construction, and the intersection of science and politics. After taking a few photos, we walked through the tunnel and onto the trail that lead us around the reservoir.
This part of our walk was particularly scenic. The morning sun’s light sparkled off the gentle waves of the lake surrounded by granite cliffs and green forest. We walked a bit further to enjoy the views and get a few steps in. I had wanted to stay longer, however, Sami was eager to head back to Yosemite Valley. I would definitely like to return to Hetch Hetchy, maybe on a backpacking trip like the one Emily and I were supposed to take a few years ago, or like the boys were completing at the time of our visit. Hiking and backpacking are the recreation activities of choice; boating and swimming in the reservoir are not allowed to maintain the purity of the water.
Still, this quiet part of Yosemite is definitely worth a visit. While the area is open all year round, access by car is dependent on Hetch Hetchy Road being open. The road is open during daylight hours and may close in the event of poor road conditions. When in doubt, be sure to check out the NPS site to plan your trip. Hetch Hetchy has miles of happy trails for many adventures. Even on a rainy morning, a walk along the O’Shaughnessy Dam and being out in the serenity of nature was refreshing to the soul.
“Hydroelectric Power Water Use Completed.” Hydroelectric Power Water Use | U.S. Geological Survey, June 2018, https://www.usgs.gov/special-topics/water-science-school/science/hydroelectric-power-water-use#:~:text=Hydropower%2C%20or%20hydroenergy%2C%20is%20a,create%20electricity%20in%20hydropower%20plants.
“The Great 1906 San Francisco Earthquake.” U.S. Geological Survey, https://earthquake.usgs.gov/earthquakes/events/1906calif/18april/.
Tuolumne River, California, https://www.rivers.gov/rivers/tuolumne.php.
Paige Blankenbuehler May 30, 2016 From the print edition Like Tweet Email Print Subscribe Donate Now. “Why Hetch Hetchy Is Staying under Water.” High Country News – Know the West, 30 May 2016, https://www.hcn.org/issues/48.9/why-hetch-hetchy-is-staying-under-water.