Which year did the Hetch Hetchy Valley flood to provide water for San Francisco?

The Hetch Hetchy Valley was flooded in 1923 to create a reservoir that would supply water to San Francisco. This action was part of a larger plan to harness the natural water resources of the Sierra Nevada mountains to meet the growing demand for water in the city. The decision to flood Hetch Hetchy was controversial, as the valley was known for its scenic beauty and was often compared to Yosemite. The reservoir, officially known as the Hetch Hetchy Reservoir, was seen as a necessary step in ensuring a reliable water supply for the expanding urban population.