page_title: O'Shaughnessy Dam (California)
section_title: Proposed removal
hierarchical_section_title: O'Shaughnessy Dam (California) / Proposed removal
caption_attribution_description: English: Hetch Hetchy Valley in Yosemite National Park Українська: Долина Хетч-Хетчі, Національний парк Йосеміті, США
context_page_description: O'Shaughnessy Dam is a 430-foot high concrete arch-gravity dam in Tuolumne County, California, in the United States. It impounds the Tuolumne River, forming the Hetch Hetchy Reservoir at the lower end of Hetch Hetchy Valley in Yosemite National Park, about 160 miles east of San Francisco. The dam and reservoir are the source for the Hetch Hetchy Aqueduct, which provides water for over two million people in San Francisco and other municipalities of the west Bay Area. The dam is named for engineer Michael O'Shaughnessy, who oversaw its construction.
  Although San Francisco had sought Tuolumne River water as early as the 1890s, this project did not move forward until the disastrous earthquake and fire of 1906, which underscored the insufficiency of the existing water supply. The Hetch Hetchy Valley – then compared to Yosemite Valley for its scenic beauty – was chosen for its water quality and hydroelectric potential, but the location within the national park generated controversy. An act of Congress was required to circumvent federal protection of the Tuolumne River, with the reasoning that public land should be developed for the public benefit.
context_section_description: O'Shaughnessy Dam has been controversial since its original construction both for its environmental impact and violations of the Raker Act by the city of San Francisco. Although the Raker Act explicitly stated that power and water from the Hetch Hetchy Project could be used only for public purposes, San Francisco has sold Hetch Hetchy power to Pacific Gas & Electric (PG&E) since 1925. Dam removal advocates have stated that San Francisco's utilization of Yosemite National Park for water and power is unfair because of the damage to tourism and the local environment caused by the dam and reservoir. By draining the reservoir, removing the dam and restoring the valley to its original state, visitors to the park would once again be able to enjoy the natural beauty of Hetch Hetchy – once compared to that of Yosemite Valley. There are other rivers and reservoirs available for San Francisco to replace the water supply, such as the city's currently unused share of water in Lake Don Pedro, the biggest reservoir on the Tuolumne River.
  Opponents of dam removal state that the estimated demolition cost of $3–10 billion is a poor investment, especially in regards of the resulting loss of renewable hydroelectric power, which would have to be replaced by polluting fossil fuel generation. Although there are several options available to replace San Francisco's water, none are of the purity currently supplied by Hetch Hetchy. There is also no guarantee that the valley can be successfully restored, as the original valley floor was actually the product of thousands of years of intensive controlled burning and management by the native Paiute and Miwok peoples that once lived in the area. Without this intervention, a forest would grow in the place of the valley's renowned meadows. Finally, the increased pressure of new tourism could cause its own environmental damage, as has been demonstrated in the crowded Yosemite Valley.
  Despite the hotly contested status of O'Shaughnessy Dam in the environmental field, and occasional federal money set aside for studying alternatives to Hetch Hetchy – such as $7 million provided by President George W. Bush in 2007 in the National Park Service budget – local support for its removal is relatively low. In 2012, San Francisco voters struck down Proposition F, which would have ordered the city to study the removal of O'Shaughnessy Dam and draft a plan to replace Hetch Hetchy water, by a vote of 77 percent against. Proposition F would have allocated $8 million to create a feasibility study by 2016; new water delivery and filtration systems would have to be in place by 2025 and Hetch Hetchy Reservoir would have to be drained by 2035.
caption: Hetch Hetchy Reservoir as seen from the dam
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