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American River Common Features Folsom Dam Modifications Folsom Dam Raise Folsom Dam Bridge
 

 

Reducing the flood risk
These improvements, when combined with the American River Common Features levee work, will reduce the risk of downstream flood damage to a 1-in-130 chance in any one year.

The Corps and its partners plan to begin work on the modifications in late 2004 and complete the changes in about 8 years. Folsom Dam Modifications will cost an estimated $200 million. The federal government will pay 65 percent of the cost and the non-federal partners (the Reclamation Board and SAFCA) will pay 35 percent.


Before 1950, American River at Fair Oaks
Annual Maximum 3 Day Flows

 

 

Pre-1950 American River flood flow

Peek Flow
Cubic feet
per second

(Thousand
CFS)

 

Historic American River Flood Flows


Since 1950, there have been five floods larger than
the previous recorded maximum flood

 

 




Major Flood Risks

  • 400,000 people
  • 170,000 structures
  • 5,000 businesses
  • 1,300 public facilities
  • 40 major roads and highways
  • $7-$15 billion in damage in a single flood event

Post-1950 American River flood flow

A large amount of sediment has accumulated along the upstream face of the dam over the last 50 years. In order to enlarge the outlets, the Corps will remove the sediment. The Corps, Reclamation Board, and SAFCA plan to work with the Bureau of Reclamation, San Juan Water District, and the cities of Folsom and Roseville to ensure that dredging activities occur during periods of low outflow that do not allow for sediment to get into the water supply.



 
   
   
n Increasing Floodwater Release Capacity
n Pre-Storm Flood Releases
n
   
The federal government will pay 65 percent of the cost and the non-federal partners (the Reclamation Board and SAFCA) will pay 35 percent.