<human>:  When was the O’Shaughnessy Dam built?
<bot>: The O’Shaughnessy Dam was built in the late 1950s and early 1960s. It was built by the Army Corps of Engineers and the U.S. Bureau of Reclamation. It is located in the San Joaquin Valley in California, and is one of the largest earth-fill dams in the world. It is also the tallest dam in the United States.