O'Shaughnessy Dam - Yosemite National Park CA
Description
The Public Works Administration (PWA) funded a major increase in the height of the O’Shaughnessy Dam, which creates Hetch Hetchy Reservoir. The dam had been completed by the city of San Francisco in 1923, after years of controversy over flooding the magnificent Hetch Hetchy Valley, the smaller twin of Yosemite Valley. This was the height of the dam-building era in America.
When San Francisco sought to expand the reservoir’s capacity, the PWA provide funding for the project, which was completed in 1937-38. The dam was raised by 86 feet and the width of the dam enlarged at the same time.
“In 1923, the Public Utilities Commission of the city and county of San Francisco expended $8,300,000 on the construction of the O’Shaughnessy Dam, which was a gravity-type arched dam, rising to a height of 226 feet above the bed of the stream. Between 1923 and 1936, due to increased population and water consumption in San Francisco and its environs, a reservoir of greater magnitude became necessary and this project was undertaken with the aid of the P.W.A. It consisted of increasing the height of the dam from its original 226 feet to a height of 312 feet, an increase of 86 feet, and in doing this the volume of concrete was practically doubled. … The enlargement of this dam was completed in 1938 at a construction cost of $3,623,634 and a project cost of $4,279,049.” (Short and Brown, p. 521)
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Plaque for raising O'Shaughnessy Dam - Yosemite National Park CA
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O'Shaughnessy Dam from approach road - Yosemite National Park CA
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Hetch Hetchy reservoir seen over O'Shaughnessy Dam - Yosemite National Park CA
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Reservoir side O'Shaughnessy Dam - Yosemite National Park CA
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Roadway on top of O'Shaughnessy Dam - Yosemite National Park CA
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Face and spillway, O'Shaughnessy Dam - Yosemite National Park CA
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Hetch Hetchy Reservoir - Yosemite National Park
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Plaques on roadway O'Shaughnessy Dam - Yosemite National Park CA
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O'Shaughnessy Dam - Yosemite National Park CA
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PWA Project card for O'Shaughnessy Dam - Yosemite National Park CA
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PWA project card showing face of O'Shaughnessy Dam - Yosemite National Park CA
Project Details
Federal Cost | Local Cost | Total Cost | Project #'s |
---|---|---|---|
$4,279,049 | $4,279,049 |
Source notes
Short, C. W. and Stanley-Brown, R. Public Buildings : a Survey of Architecture of Projects Constructed by Federal and Other Governmental Bodies between the Years 1933 and 1939 with the Assistance of the Public Works Administration. Washington, D.C. : Public Works Administration : U.S. G.P.O., 1939.
https://en.wikipedia.org/wiki/Hetch_Hetchy
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A tribute to man’s ingenuity. The storage of water to supply people downstream with a totally gravity fed system. I love it.