Folsom Dam Modifications
Record storms in 1986 raised concerns over the ability of Folsom Dam and Sacramento’s flood control system to handle another such storm. This led to a partnership between the U.S. Army Corps of Engineers (Corps), the Reclamation Board of the State of California (Reclamation Board) and the Sacramento Area Flood Control Agency (SAFCA) to find ways to reduce Sacramento’s flood risk. The Folsom Dam Modification Project is a significant part of that effort.

Folsom Dam and Reservoir are located on the American River about 25 miles east of the city of Sacramento. The reservoir has a total storage capacity of 977,000 acre-feet. Its flood control storage space ranges from 400,000 to 670,000 acre-feet depending on the amount of vacant space in upstream reservoirs.

The Corps built Folsom Dam in 1955, and the U.S. Bureau of Reclamation operates it. Using flood data from the first half of the 20th century, engineers designed Folsom to provide a 250-year (1 chance in 250) level of flood protection. In the 50 years since it was completed, Folsom has had to control floodwater from the largest storms of record.