Hetch Hetchy Reservoir

Surface Elevation 3,783 ft (1,153 m)

Hetch Hetchy Reservoir is a reservoir in Yosemite National Park, about 65 miles northeast from the city of Merced, California. The reservoir has a capacity of 360,000 acre·ft and is formed by the 364 ft concrete gravity O'Shaughnessy Dam in Hetch Hetchy Valley on the Tuolumne River. After a years-long battle against the dam, led by John Muir, the dam was approved under the administration of Woodrow Wilson in 1913 and was completed in 1923. It is owned by the City and County of San Francisco.

The primary purpose is to supply drinking water to the San Francisco Bay Area. It is one of nine reservoirs in San Francisco's system and holds about 25% of its overall storage capacity. The water is transported from the reservoir by the Hetch Hetchy Aqueduct. Hydroelectricity is also produced by Kirkwood Powerhouse and Moccasin Powerhouse, which have a capacity of 118 and 100 megawatts, respectively. Because Hetch Hetchy is a municipal water supply and its water is not filtered, swimming and boating are prohibited. Fishing is permitted only from the lake shore.