O'Shaughnessy Dam

Construction work on the dam in August 1922 ©Image Attribution forthcoming. Image belongs to the respective owner(s).

1923 Jan 1

O'Shaughnessy Dam

Tuolumne County, California, U

In 1923, the O'Shaughnessy Dam was completed on the Tuolumne River, flooding the entire valley under the Hetch Hetchy Reservoir. The dam and reservoir are the centerpiece of the Hetch Hetchy Project, which in 1934 began to deliver water 167 miles (269 km) west to San Francisco and its client municipalities in the greater San Francisco Bay Area.

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O'Shaughnessy Dam