In the late 19th century , the city of San Francisco was rapidly outgrowing its limited water supply , which depended on intermittent local springs and streams . The city looked east to the Sierra Nevada , where snowmelt fed the headwaters for many of California 's largest rivers . In 1890 , San Francisco mayor James D. Phelan proposed to build a dam and aqueduct on the Tuolumne River , one of the largest southern Sierra rivers , as a way to increase and stabilize the city 's water supply . In 1900 , a United States Geological Survey ( USGS ) report also described the Tuolumne River as " the best source of sustainable water for San Francisco " . Although Phelan managed to secure water rights for the Tuolumne River in 1901 , his appeals to the federal government for development of the Hetch Hetchy Valley were unsuccessful . But when the 1906 San Francisco earthquake and subsequent fire razed the city , the dangerous inadequacies of the city 's water supply system were brought to national light
1906 San Francisco earthquake
1906 San Francisco earthquake
O'Shaughnessy Dam (California)