Construction of the dam began in 1951 with preliminary excavations for the Folsom Power Plant. The primary contract was awarded to Savin Construction Corp. of East Hartford, Connecticut, and Merritt-Chapman & Scott of New York for $29.5 million, with oversight by the U.S. Army Corps of Engineers. On October 29, 1952, the first concrete was poured for the foundation. Flooding washed out the temporary cofferdam three times in 1953, delaying work and causing damage to Nimbus Dam which was also under construction at the time. Water storage in Folsom Lake began in February 1955, and the final concrete in the main dam was poured on May 17, 1955. The first hydroelectric power was generated in September of that year. In order to acquire the necessary land in the future Folsom Lake bed, the government had to relocate families on 142 properties, including the settlements of Mormon Island and Salmon Falls.