“Bite-Size Bits of Local, National, and Global History”
“Bite-Size Bits of Local, National, and Global History”
Near Groveland in Tuolumne County, California — The American West (Pacific Coastal)

Hetch Hetchy Reservoir and O’Shaughnessy Dam

Hetch Hetchy Reservoir and O'Shaughnessy Dam image. Click for full size.
Photographed By Karen Key, June 22, 2007
1. Hetch Hetchy Reservoir and O'Shaughnessy Dam
The great 1906 San Francisco earthquake destroyed key portions of the City of San Francisco’s water system. The three days of unquenchable fires that followed the quake claimed more than four square miles of land, thousands of buildings and an untold number of lives. The devastation spurred City leaders to pursue a more reliable source of water for the future.

After intense national debate about building a reservoir and dam in a national park, Congress passed the Raker Act in 1913, granting San Francisco the rights-of-way and the use of public lands to build the Hetch Hetchy Water and Power Project. John Muir, who wanted the valley to remain untouched for wilderness preservation, had led the opposition.

This complex system of tunnels, pipelines and facilities took 20 years to build and transports snowmelt 167 miles entirely by gravity, without the use of pumps. Today this water serves more than 2.4 million people in four counties in the San Francisco Bay Area, as well as the residents of Groveland.

(caption) Phase I of construction of O’Shaughnessy Dam was completed in 1923 and phase 2 ended in
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1938 when the dam was raised another 85.5 feet to 312 feet in height. Present capacity for the reservoir is 117 billion gallons of water or the equivalent of 177,914 Olympic-slzed pools The dam crest is 910 feet long and 289 feet wide at the base.

(caption) Steel anchor bars were constructed between old and new concrete at O’Shaughnessy Dam when its height was raised in 1937.

(caption) After serving for twenty years as Chief Engineer, Michael Maurice O’Shaughnessy died just twelve days before the public dedication of the completion of the project at Pulgas Water Temple in 1934.
Topics. This historical marker is listed in these topic lists: Industry & CommerceWaterways & Vessels. A significant historical year for this entry is 1906.
Location. 37° 56.859′ N, 119° 47.273′ W. Marker is near Groveland, California, in Tuolumne County. Marker can be reached from Hetch Hetchy Road. Touch for map. Marker is in this post office area: Groveland CA 95321, United States of America. Touch for directions.
Other nearby markers. At least 8 other markers are within 18 miles of this marker, measured as the crow flies. O’Shaughnessy Dam (here, next to this marker); Producing Clean Renewable Energy (here, next to this marker); Water Quality at Hetch Hetchy (here, next to this marker); Trails and Waterfalls (here, next to this marker); Hetch Hetchy Railroad (here,
Hetch Hetchy Reservoir image. Click for full size.
Photographed By Karen Key, June 22, 2007
2. Hetch Hetchy Reservoir
O'Shaughnessy Dam in the distance
next to this marker); John Muir... The Woodcutter (approx. 17.3 miles away); The Ahwahneechee (approx. 17.4 miles away); James Hutchings (approx. 17˝ miles away). Touch for a list and map of all markers in Groveland.
O'Shaughnessy Dam image. Click for full size.
Photographed By Karen Key, June 22, 2007
3. O'Shaughnessy Dam
Credits. This page was last revised on August 18, 2020. It was originally submitted on July 29, 2007, by Karen Key of Sacramento, California. This page has been viewed 2,112 times since then and 83 times this year. Photos:   1, 2, 3. submitted on July 29, 2007, by Karen Key of Sacramento, California. • J. J. Prats was the editor who published this page.

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Dec. 11, 2023