Hetch Hetchy Reservoir, lac de barrage dans le parc national de Yosemite, en Californie
Hetch Hetchy Reservoir is a water body in the northern part of Yosemite Valley that supplies drinking water to San Francisco and sits behind the 312-foot-tall O'Shaughnessy Dam. The water extends for miles, reflecting the surrounding mountains, while waterfalls like the 1,000-foot Wapama Falls plunge from steep rocky cliffs.
The valley was shaped by rivers and glaciers like Yosemite Valley but met a different fate: after the 1906 earthquake, San Francisco decided to build a dam to secure drinking water. Construction began in 1919 using a mountain railroad to transport materials, and was completed in 1923, flooding the original valley with the reservoir.
The reservoir takes its name from a Miwok word, reflecting the original presence of indigenous peoples in this valley. Today, visitors use the area mainly for hiking and bird watching, with the dam itself serving as a visible reminder of how humans have shaped the landscape.
Access is via Evergreen Road, which branches off from Highway 120 about a mile outside the park entrance and climbs for several miles. Bring plenty of water, snacks, and sturdy footwear, especially if you plan to explore the trails, with parking available near the O'Shaughnessy Dam.
The valley beneath the reservoir remains completely submerged, with granite cliffs and waterfalls that no visitor can see. Today there are ongoing discussions about whether the dam should be removed to restore the original valley and enable new recreational activities like boating.
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