Last updated: January 11, 2024
Place
O'Shaughnessy Dam
![A large body of water is seen in the distance behind a wayside exhibit.](/common/uploads/place/import/4a15dc3e-e664-4664-9302-11041b4e61de_image_350.jpg)
Named for the chief engineer, the O’Shaughnessy Dam was completed in 1938 and is 430-feet tall. Today the 117-billion-gallon reservoir supplies drinking water to about 2.5 million San Francisco Bay Area residents and industrial users. It also supplies hydro-electric power generated by two plants downstream. The reservoir is eight miles long and the largest single body of water in Yosemite.