Hetch Hetchy

Hetch Hetchy is a glacially carved valley in the northwestern section of Yosemite National Park in California, drained by the Tuolumne River. The valley floor sits at about 3,783 feet in elevation and once ran roughly 3 miles long and half a mile wide, similar in character to the nearby Yosemite Valley. Native Americans inhabited and managed the valley for millennia before American settlement in the 1850s. In 1913 Congress authorized a dam across the valley, and the O'Shaughnessy Dam, completed in 1923, submerged the valley floor to create a reservoir that has supplied water to San Francisco and the Bay Area since 1934. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/