The Hetch Hetchy Valley is on the Tuolumne River in central California's Yosemite National Park.

It once rivaled Yosemite Valley in beauty and grandeur, but the construction of O'Shaughnessy Dam in 1923 turned the valley into the 14 km (9 mi) long Hetch Hetchy Reservoir, which is used for generating electricity and for supplying water to San Francisco via a 251 km (156 mi) long aqueduct. There is a viewpoint not far from the dam.

There are several scenic waterfalls in the Hetch Hetchy Valley. The 330 m (1,080 ft) high Wapama Falls and the 260 m (840 ft) high Tueeulala Falls are both located on the northern side of the valley. The Rancheria Falls is located on the Rancheria Creek farther southeast.

The region is home to a variety of plants and animals.

Hetch Hetchy Valley ©Tyke Jones

O'Shaughnessy Dam ©Tyke Jones

Hetch Hetchy Reservoir ©Tyke Jones