New Melones Dam is an earth and rock filled dam across the Stanislaus River creating New Melones Lake. Situated between Calaveras and Tuolumne County, California in the Sierra Nevada foothills near Jamestown, the dam was completed in 1979 replacing the old Melones Dam.
The dam was constructed to replace the 183 ft (56 m) tall Melones Dam, an arch dam which was constructed in 1926 by the Oakdale and South San Joaquin Irrigation Districts. The new dam was authorized by the Flood Control Act of 1944 and reauthorized by the Flood Control Act of 1966 with an increase in height from a 355 ft (108 m) arch dam to 625 ft (191 m) tall embankment dam. Construction on the New Melones Dam began in July 1966 and the diversion tunnel was complete by 1973. On March 6, 1974, construction on the dam began and it was completed on October 28, 1978. By the end of 1978, the power plant was complete and it was commissioned in 1979. The filling of the reservoir began in 1983.