State of the Infrastructure: A Joint Report by the Bureau of Reclamation and the U.S. Army Corps of Engineers [open pdf - 2MB]
From the Document: "The U.S. Army Corps of Engineers (Army Corps) and the Bureau of Reclamation (Reclamation) collaborated on a critical infrastructure project to construct the Folsom Dam auxiliary spillway, also known as the Joint Federal Project. Reclamation and the Army Corps, along with other cooperating agencies, formed an unprecedented partnership to address dam safety issues associated with extreme floods and to provide enhanced flood risk reduction for the Sacramento area - one of the most at-risk communities in the Nation. The auxiliary spillway was constructed adjacent to Folsom's main concrete dam, 23 miles northeast of Sacramento. It includes a 1,100-foot-long approach channel beginning in Folsom Reservoir, a concrete control structure with six bulkheads and six radial gates, a 3,100-foot-long auxiliary spillway chute, and a stilling basin that acts as an energy dissipation structure as water discharges and enters the American River. With the ability to operate the new spillway, large floods can be better managed by safely releasing more water from Folsom Reservoir earlier in a storm through both the spillway gates on Folsom Dam and the new control structure's radial gates, thereby reducing hydrologic risk and leaving more storage capacity in the reservoir."
U.S. Bureau of Reclamation: http://www.usbr.gov/