The Upper Tuolumne watershed, located in central California and covering approximately 1,687 square miles, is an important source of water for the San Francisco Bay Area. The watershed is characterized by rugged mountain terrain, with elevations ranging from 3,000 to 13,000 feet. The hydrology of the watershed is heavily influenced by snowpack, which accounts for up to 70% of the annual water supply. The Tuolumne River, which is fed by snowmelt and rainfall, provides water for the Hetch Hetchy Reservoir, a significant source of drinking water for the Bay Area. The reservoir also contains sediment and other constituents, which can affect water quality. Climate trends in the watershed indicate an increase in temperatures and changes in precipitation patterns, which could affect the snowpack and water availability in the future.