Lake Eleanor is a reservoir located in Hetch Hetchy Valley, California. The reservoir was constructed in the early 1900s to provide water and hydroelectricity to San Francisco. The lake is fed by the Tuolumne River and is surrounded by the Sierra Nevada mountains. The hydrology of the area is influenced by the snowmelt from the surrounding mountains. The lake provides surface water for San Francisco, Modesto, and Turlock, and also supports hydropower generation. The area around the lake is not used for agriculture, but is popular for recreational activities such as camping, hiking, and fishing. The lake has a capacity of 28,000 acre-feet and is managed by the San Francisco Public Utilities Commission. The surrounding area is protected by the Yosemite National Park.