Starting in the 1940s , the federal government had also sought to build a high dam at the Melones site . The Flood Control Act of 1944 authorized the U.S. Army Corps of Engineers to build a flood control structure with about four times the capacity of the irrigation districts ' dam . However , they were unable to provided a sound economic justification for the project on flood control alone . In the 1950s , the U.S. Bureau of Reclamation proposed a much larger dam with a capacity of 2.4 million acre feet ( 3.0 km3 ) , which would capture most of the extra floodwaters that the existing small irrigation dams could not hold . It would be a multi-purpose unit of the Central Valley Project , providing irrigation , flood control , hydropower and fishery flows . Locals initially criticized the project , saying that it was too big , a waste of federal money , and the reservoir would never fill . There was also concern that the Bureau of Reclamation was attempting a " water grab " that would take the extra water to meet obligations outside the Stanislaus River Basin . However , after the Christmas flood of 1964 caused massive destruction along the Stanislaus River , New Melones gained political support . After federal funding was approved , construction started in 1966
Christmas flood of 1964
Christmas flood of 1964
Stanislaus River