In the early 1960s , there was some local opposition to the project on the grounds that it was too big – with a reservoir more than twice as large as the annual flow of the Stanislaus River , it might never fill and would be a waste of federal Central Valley Project funds . There was also concern that water from New Melones II might be exported outside the Stanislaus River basin and sold elsewhere ; therefore , a rider attached to the 1962 act " reserved water for use within the basin with export of excess water only " . Two years later , the Christmas flood of 1964 caused considerable damage along the Stanislaus River that a large dam could have prevented ; Congressman John J. McFall " seized the political leverage that only the floods could provide , and urged the drenched farmers to support New Melones Dam . " With opposition having largely turned to support , Congress approved funding in 1965 , with construction starting the following year
Christmas flood of 1964
Christmas flood of 1964
New Melones Dam