page_title: Tuolumne River
section_title: Hetch Hetchy Project
hierarchical_section_title: Tuolumne River / Irrigation, power and water supply / Hetch Hetchy Project
caption_attribution_description: English: Spillway at Hetch Hetchy Reservoir, California
context_page_description: The Tuolumne River flows for 149 miles through Central California, from the high Sierra Nevada to join the San Joaquin River in the Central Valley. Originating at over 8,000 feet above sea level in Yosemite National Park, the Tuolumne drains a rugged watershed of 1,958 square miles, carving a series of canyons through the western slope of the Sierra. While the upper Tuolumne is a fast-flowing mountain stream, the lower river crosses a broad, fertile and extensively cultivated alluvial plain. Like most other central California rivers, the Tuolumne is dammed multiple times for irrigation and the generation of hydroelectricity.
  Humans have inhabited the Tuolumne River area for up to 10,000 years. Prior to the arrival of Europeans, the river canyon provided an important summer hunting ground and a trade route between Native Americans in the Central Valley to the west and the Great Basin to the east. First named in 1806 by a Spanish explorer after a nearby indigenous village, the Tuolumne was heavily prospected during the California Gold Rush in the 1850s, and the lower valley was cultivated by American settlers over the next few decades.
context_section_description: San Francisco did not move forward with plans to divert the Tuolumne until the 1906 San Francisco earthquake and subsequent fires devastated the city, proving the inadequacy of the existing water system. After exploring fourteen sites throughout Central California, San Francisco had settled on the Tuolumne's Hetch Hetchy Valley as the ideal location to develop storage and hydroelectric power. Because the area had been located inside Yosemite National Park since 1890, the city petitioned for Congress to pass the Raker Act. Signed in 1913 by President Woodrow Wilson, the Act allowed San Francisco to dam the Tuolumne River, as long as the water and power provided would be reserved exclusively for public utility, not private sale.
  The Hetch Hetchy Valley became the center of the first major environmental controversy in the United States. John Muir, the leader of the Sierra Club, spearheaded a legal battle against the proposed O'Shaughnessy Dam, famously stating – "Dam Hetch Hetchy! As well dam for water-tanks the peoples' cathedrals and churches, for no holier temple has ever been consecrated by the heart of man." The Hetch Hetchy debacle is often credited with birthing modern environmentalism, sharply dividing the conservation movement – which favored the development of natural resources for public benefit – and the preservationists, who believed that sites of scenic value like Hetch Hetchy were better left for public recreation and enjoyment.
  Despite the controversy, the city of San Francisco pushed through, beginning construction in early 1914 and filling the reservoir for the first time in May 1923. The Hetch Hetchy Railroad was built along 68 miles (109 km) of the Tuolumne River Canyon to provide access to the remote construction site. Hydroelectric power reached San Francisco by 1925, but the first water was not delivered until 1934. Today, San Francisco diverts about 33 percent of the flow of the Tuolumne at Hetch Hetchy, or 14 percent of the river's total flow.
caption: Hetch Hetchy Reservoir and spillway
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