O'Shaughnessy Dam (California)

O'Shaughnessy Dam is a 430 ft (130 m) high concrete arch-gravity dam in Tuolumne County, California, in the United States. The dam impounds the Tuolumne River at the lower end of Hetch Hetchy Valley in Yosemite National Park, about 160 mi (260 km) east of San Francisco. The dam and reservoir serves as the primary water source for the Hetch Hetchy Project, which provides municipal water in the San Francisco Bay Area. Construction of the dam started in 1919 and was finished in 1923,^[7] with the first water delivered in 1934. The dam is named for engineer Michael O'Shaughnessy, who oversaw its construction.^[8]

• http://en.wikipedia.org/wiki/O'Shaughnessy Dam (California)
• The National Parks: America's Best Idea