U.S. Congress Approves a Dam in Hetch Hetchy Valley Summary

  • Last updated on November 10, 2022

After intensive lobbying by the city of San Francisco, the U.S. Congress approved the building of a dam in Yosemite National Park, despite objections to the project as an intrusion on the sanctity of the park.

Summary of Event

On December 19, 1913, President Woodrow Wilson signed a bill that permitted construction of a dam across Hetch Hetchy Valley in California’s Yosemite National Park. The dam would impound water from the Tuolumne River and supply the growing and water-poor city of San Francisco, 175 miles away, with an additional source of drinking water. The reservoir and dam would also provide the city with hydroelectric power to meet its own needs and to sell at a profit. Wilson’s signature on the bill ended a decade of often bitter controversy, and it demonstrated that the nation’s national parks were not as sacrosanct as their supporters had believed. O’Shaughnessy Dam[Oshaughnessy Dam] Yosemite National Park Water;access Wilderness preservation Dams;O’Shaughnessy (Hetch Hetchy Valley)[Oshaughnessy] Conservation;wilderness Hetch Hetchy Valley [kw]U.S. Congress Approves a Dam in Hetch Hetchy Valley (Dec. 19, 1913) [kw]Congress Approves a Dam in Hetch Hetchy Valley, U.S. (Dec. 19, 1913) [kw]Dam in Hetch Hetchy Valley, U.S. Congress Approves a (Dec. 19, 1913) [kw]Hetch Hetchy Valley, U.S. Congress Approves a Dam in (Dec. 19, 1913) O’Shaughnessy Dam[Oshaughnessy Dam] Yosemite National Park Water;access Wilderness preservation Dams;O’Shaughnessy (Hetch Hetchy Valley)[Oshaughnessy] Conservation;wilderness Hetch Hetchy Valley [g]United States;Dec. 19, 1913: U.S. Congress Approves a Dam in Hetch Hetchy Valley[03470] [c]Environmental issues;Dec. 19, 1913: U.S. Congress Approves a Dam in Hetch Hetchy Valley[03470] [c]Laws, acts, and legal history;Dec. 19, 1913: U.S. Congress Approves a Dam in Hetch Hetchy Valley[03470] [c]Natural resources;Dec. 19, 1913: U.S. Congress Approves a Dam in Hetch Hetchy Valley[03470] Muir, John Pinchot, Gifford

Hetch Hetchy Valley is one of two major valleys in Yosemite National Park. The other, Yosemite Valley, about fifteen miles south and east of Hetch Hetchy Valley, is a popular site for visitors to the area. The early exploration of Yosemite Valley is better documented than that of Hetch Hetchy Valley. The first record of European exploration of Yosemite is an 1849 diary entry by William Penn Abrams, a hunter. In 1851, a U.S. Army contingent, the Mariposa Battalion, carried out a campaign in the valley to subdue a Native American tribe camped there. Stories of the awesome beauty of the Yosemite area appeared in newspapers and magazines, and parties of tourists visited Yosemite Valley as early as 1855.

John Muir.

(Library of Congress)

The growing public interest in the rugged mountain scenery of Yosemite Valley did not pass unnoticed. The California legislature and Governor Frederick F. Low appointed a park commission headed by Frederick Law Olmsted, Olmsted, Frederick Law, Sr. the designer and developer of New York City’s Central Park. The commission also included California state geologist Josiah Dwight Whitney. Whitney, Josiah Dwight The commissioners authorized a survey of the Yosemite area, including Hetch Hetchy Valley. The resulting 1868 report of the California Geological Survey, written by Whitney, provides the earliest detailed description of Hetch Hetchy. In dry, technical prose, the report describes Hetch Hetchy Valley as a striking counterpart of the better-known Yosemite Valley. It was Yosemite Valley that visitors sought, however, and the lesser-known and less accessible Hetch Hetchy remained largely ignored.

California had gained a foothold in the area when, in 1864, President Abraham Lincoln signed an act that gave Yosemite Valley and the nearby Mariposa Grove of giant sequoia trees to California for use as a state park. In an 1865 report to the California Park Commission, Olmsted predicted that millions of visitors would stream into the valley to view the awesome scenery, and he recommended that the valley be protected against any activities that might destroy its natural beauty. His report was not warmly received, and the commission shelved it. All this was to change, however, when John Muir came on the scene.

One of his contemporaries described Muir as a sort of bearded wood sprite. He exuded a missionary’s zeal about protecting and preserving the natural beauty of his beloved Sierra Nevada. The watersheds of the Merced River, which flowed through Yosemite Valley, and of the Tuolumne River, which flowed through Hetch Hetchy Valley, were special icons to him, to be guarded at all costs. To gain public support for his views, Muir published articles in national magazines in which he described the wonders of the area in glowing terms. The public responded by filling Yosemite Valley with tourist tents and horse-drawn caravans. Muir also lobbied national political figures, and, largely as the result of his missionary activities, Yosemite National Park was established in 1890. The new park enclosed the state park, and the two were separately administered. In 1906, California turned the Yosemite Valley and the Mariposa Grove over to the federal government. California had not forgotten its need for water and hydroelectric power, however, and it had not forgotten Hetch Hetchy Valley.

From an engineering standpoint, Hetch Hetchy Valley was nearly ideal as a site for a reservoir. The valley floor was nearly four miles long and varied in width from one-fourth to one-half mile. The narrowest portion of the valley lent itself easily to the construction of a masonry-and-concrete dam. Part of the valley floor was a one-mile-long meadow with trees restricted to the river banks and the sides of the valley. The most abundant trees were ponderosa pine and sugar pine, with a sprinkling of Douglas fir. Some of the trees were more than two hundred feet tall, and all of the varieties were valued for timber.

Advocates of building a dam noted that the trees could be cut and sold for timber. This would prevent waste of the timber, would provide additional funds, and would clear the valley floor of potentially dangerous floating debris. Muir and the newly founded Sierra Club were outraged at what they believed was a desecration of part of the national heritage. Muir continued to lobby the president and sought an ally in Gifford Pinchot.

Pinchot, who had been trained in Europe in the science of forestry, had been appointed chief forester of the Division of Forestry in the U.S. Department of Agriculture in 1898. Pinchot was well respected, and he personally liked Muir. Muir soon discovered, however, that he would get no support from Pinchot, who agreed with the supporters of the proposal to dam Hetch Hetchy.

In 1901, the city of San Francisco petitioned the U.S. Congress for permission to dam the Tuolumne River, but the petition was rejected in 1903. Later, however, the devastation resulting from the 1906 San Francisco earthquake and the plight of the city’s people aroused the sympathy of the nation and the federal government, and in 1908 Secretary of the Interior James A. Garfield awarded the city a permit to dam the river. The permit was upheld by both houses of Congress. A bill sponsored by Representative John E. Raker, Raker, John E. whose congressional district included Yosemite Park, passed easily in Congress, and in 1913, Wilson signed the law that gave San Francisco free rein in Hetch Hetchy Valley. The loss of his beloved Hetch Hetchy Valley was a grievous blow to Muir. He died on December 24, 1914, some say of a broken heart.

The dam, named O’Shaughnessy Dam for the city engineer of San Francisco, M. M. O’Shaughnessy, was not completed until 1923. It is more than four hundred feet high and impounds a reservoir that is two hundred feet deep in places. Some of the water goes to satisfy the needs of San Francisco, and some generates power used in the city; sale of the surplus power provides the city with a source of revenue.


Although Hetch Hetchy Valley was lost as a habitat for wildlife, some proponents of the dam project saw it as an ecological trade-off. Habitat had been lost, but the resulting reservoir provided a lake where none had existed before. Moreover, the impounded water ensured that waterfalls on the lower Tuolumne River did not dry up during the summer months but rather continued to flow during the peak tourist season.

Perhaps the most damaging effect of the dam was the loss of sanctuary in the park. Muir, Olmsted, and others viewed the national parks as places where people could escape the pressures of life in built-up cities and towns. With the construction of the dam in Hetch Hetchy Valley, a precedent had been established. Hotels and campsites in Yosemite Valley had helped visitors enjoy the park, but large-scale development not in keeping with the naturalness of the park had not been permitted. Construction of the dam and reservoir clearly demonstrated that in the face of sufficient political pressure, even the nation’s most beautiful natural areas could be put at risk.

The building of the dam and the subsequent flooding of the valley had little real ecological impact on Yosemite National Park as a whole. Hetch Hetchy Valley was smaller than Yosemite Valley, and its geographic and geologic features were not as magnificent as its neighbor’s. It was not as accessible as Yosemite Valley, it lacked Yosemite’s hotels and camps, and it was visited by few tourists. The dam and the artificial lake were thus more or less hidden away and did not spoil the casual visitor’s enjoyment of the mountain scenery in the park.

The real impact of the damming of the Tuolumne River in Hetch Hetchy Valley was its effect on citizens at large. It became clear to many Americans that the national parks, which were created to provide inspiration and education, might become resorts and exploitable resources. The battle was joined between the preservationists, whose spokesman was John Muir, and the conservationists, whose spokesman was Gifford Pinchot. Muir saw nature as a good for its own sake. Pinchot saw control of the earth to be humanity’s principal work.

The struggle between these opposing groups led to the establishment of citizen watchdog organizations to protect the parks. Muir’s fight to save Hetch Hetchy Valley from the dam builders moved forward when he founded the Sierra Club Sierra Club in 1892. In the twenty-first century, the Sierra Club continues to be a strong and effective voice in battles to protect the environment. Also active, especially in the Florida Everglades, is the National Audubon Society, which was founded in 1905 to protect birds. Other longtime citizen-activist groups concerned with environmental issues include the National Wildlife Federation, the Izaak Walton League, the Nature Conservancy, and the National Parks and Conservation Association National Parks and Conservation Association (NPCA).

The NPCA came into being on May 19, 1919, as the National Parks Association; its mission is to champion the national parks and protect their integrity. A major focus of this organization is the role of the national parks as outdoor classrooms where visitors can be educated. In addition to promoting and enhancing the educational function of the parks, the NPCA also fights against development projects that might damage individual parks. In 1992, the organization joined a successful battle to prevent energy drilling adjacent to Carlsbad Caverns National Park in New Mexico. The NPCA also opposed proposals to allow strip mining near Cumberland Gap National Historical Park in Virginia and helped prevent construction of a major theme park and shopping malls near national parks that preserve important Civil War battlefields.

At the beginning of the twenty-first century, the U.S. national parks in general and Yosemite National Park in particular face a dilemma: whether to focus on preservation or to encourage tourism that may be detrimental to the parks’ purity. Park managers are loath to place too many restrictions on park visitors, many of whom consider entrance to a national park to be their sacred right. According to NPCA polling data, however, public attitudes are generally supportive of steps that parks could take to reduce overcrowding, such as charging reasonable user fees, reducing automobile traffic, and regulating activities such as the use of snowmobiles.

The loss of Hetch Hetchy in 1913 was a blow to the preservation movement, but the event also served to galvanize preservationists, who began to organize so that they could work effectively to prevent similar episodes in the future. O’Shaughnessy Dam[Oshaughnessy Dam] Yosemite National Park Water;access Wilderness preservation Dams;O’Shaughnessy (Hetch Hetchy Valley)[Oshaughnessy] Conservation;wilderness Hetch Hetchy Valley

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Hays, Samuel P. Conservation and the Gospel of Efficiency. 1959. Reprint. Pittsburgh: University of Pittsburgh Press, 1999. Seminal study of the early history of conservation in the United States. Argues that most early conservationists were dedicated to efficient use of natural resources rather than to preservation as an end in itself.
  • citation-type="booksimple"

    xlink:type="simple">Jones, Holway R. John Muir and the Sierra Club: The Battle for Yosemite. San Francisco: Sierra Club Books, 1965. The classic book on the battle to protect Yosemite National Park and, especially, Hetch Hetchy Valley. Lucidly written and well supported with documentation of original sources. Many excellent photographs of Hetch Hetchy Valley before and after construction of the dam as well as photographs of the people involved in the battle.
  • citation-type="booksimple"

    xlink:type="simple">Lewis, Jack. “Glimpses of Pinchot.” EPA Journal 17, no. 5 (November/December, 1991): 59-61. A brief retrospective of the father of American forestry, with selected quotations from his works. Reveals details of the friendship between Pinchot and Muir that was destroyed by Pinchot’s support of the Hetch Hetchy project. Clearly shows Pinchot’s leanings toward utilization, rather than mere preservation, of natural resources.
  • citation-type="booksimple"

    xlink:type="simple">Mitchell, John G. “Uncluttering Yosemite.” Audubon 92 (November, 1990): 72-94. Good discussion of human effects on Yosemite National Park. Examines the first use of automobiles in the park, the Hetch Hetchy controversy, and the overcrowding that has resulted from the park’s popularity.
  • citation-type="booksimple"

    xlink:type="simple">Muir, John. The Yosemite. 1912. Reprint. New York: Modern Library, 2003. An excellent glimpse into Muir’s personality and his struggle to protect his beloved Yosemite. The tone is lyrical in places, providing the reader with vivid word pictures of the High Sierra scenery. Curiously, Muir shows no bitterness, although at the time of the writing the fate of Hetch Hetchy had been decided.
  • citation-type="booksimple"

    xlink:type="simple">Nash, Roderick Frazier. Wilderness and the American Mind. 4th ed. New Haven, Conn.: Yale University Press, 2001. Intellectual history of Americans’ relationship with the wilderness, beginning with the earliest days of European contact. Includes bibliography and index.
  • citation-type="booksimple"

    xlink:type="simple">Parshall, Gerald. “A Knight in the Wilderness: Sierra Club Founder John Muir Launched a Movement a Century Ago.” U.S. News & World Report, July 20, 1992, 57-58. Succinctly describes Muir’s ability to enlist the help of the wealthy and powerful to protect Yosemite.
  • citation-type="booksimple"

    xlink:type="simple">Pope, Carl. “Undamming Hetch Hetchy.” Sierra 72 (November/December, 1987): 34-38. Pope, the Sierra Club’s director of conservation, describes a 1987 proposal by U.S. secretary of the interior Donald Hodel to restore Hetch Hetchy Valley. The Sierra Club leadership was pleased at the prospect and was disappointed when the proposal fell through. A good look at political maneuvering in the environmental movement.
  • citation-type="booksimple"

    xlink:type="simple">Runte, Alfred. Yosemite: The Embattled Wilderness. Lincoln: University of Nebraska Press, 1990. A scholarly, well-documented volume. The author, a historian specializing in national parks, writes in a light, academic tone and presents an unbiased discussion of the Hetch Hetchy Valley controversy. Includes valuable citations of primary sources and well-chosen photographs.
  • citation-type="booksimple"

    xlink:type="simple">Sanborn, Margaret. Yosemite: Its Discovery, Its Wonders, and Its People. New York: Random House, 1981. Looks at Yosemite from the tourist’s point of view. Good for another viewpoint on the park’s problems.

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