American River History
Folscom Dam Modificiations
Folsdom Dam Raise
In the News
Increasing floodwater release
Currently, the dam does not have sufficient
outlet capability to make effective releases in preparation for one of
these large storms. Releases through the existing eight outlets combined
with releases through the powerhouse are limited to approximately 35,000
cubic feet per second (cfs). This is less than one-third of the capacity
of the American River levees to pass floodwater. The levees can safely
contain 145,000 cfs during flood operations. In order to make these large
flood releases, the reservoir must be nearly 75 percent full and the water
in the reservoir high enough to pass through the spillway gates near the
top of the dam. By that time, the flood control space behind the dam is
approximately 40 percent filled.
Enlarging the existing outlet gates and adding
two new outlets will allow for larger releases of up to 115,000 cfs earlier
during a flood event. This will create additional floodwater storage space
behind the dam, which will, in turn, reduce the peak amounts of floodwater
sent down the American River. The result is greater flood protection.
The existing eight outlet gates consist of an upper
row of four gates and a lower row of four gates. The Corps and its partners
began work in 2004. They plan to begin to enlarge the upper row of gates
and to add two new gates to this row in the summer of 2005. The work will
take approximately 6 years to complete and will be scheduled to allow
Folsom Dam to continue at its current level of flood operation, water
supply, and power service during construction.
In 2009, operations will begin to enlarge at least
two of the lower outlet gates.
All Folsom Dam modifications are scheduled for completion in 2013.
through the existing eight outlets combined with releases through the
powerhouse are limited to approximately 35,000 cubic feet per second (cfs).
This is less than one-third of the capacity of the American River levees
to pass floodwater.