On Tuesday, November 23, 2010, the Bureau of Reclamation increased releases from Nimbus Dam into the lower American River from 2,000 to 3,800 cubic feet per second (cfs) for flood control management. Nimbus Dam, located 7 miles downstream of Folsom Dam and Powerplant, is a regulatory dam that forms Lake Natoma. Nimbus Dam's primary purposes are to control flow in the lower American River and produce power.

Intermittent higher releases of up to 7,000 cfs are expected as storage levels at Folsom Reservoir continue to encroach into the required flood control space, estimated to be about 460,000 acre-feet by the end of November. The current storage in Folsom Reservoir is approximately 580,000 acre-feet. Beginning Sunday evening, November 28, 2010, flows in the river will remain at up to 7,000 cfs for approximately 2 days, then the flows will be reduced to a base of 3,800 cfs. These 2-day pulses will continue until the flood control reservation requirement in Folsom Reservoir is met. Termination of the flow pulse is likely to occur before Wednesday, December 15, 2010, depending on Folsom inflow and storage conditions.

People recreating in or along the lower American River downstream of Nimbus Dam to the confluence of the American and Sacramento Rivers should take appropriate safety precautions during the river flow cycles beginning on Sunday, November 28, 2010. From that date on, up to 2,500 cfs of the total release from Nimbus Dam will occur through the Nimbus Powerplant with the remaining release through the Nimbus Dam spillway.

The release schedule addresses fisheries needs as well as the requirements set by the Sacramento Area Flood Control Agency flood protection agreement. The releases are part of a coordinated effort between the California Department of Fish and Game, the National Marine Fisheries Service, the U.S. Fish and Wildlife Service and Reclamation to ensure lower American River flows are consistent with current Biological Opinions (BO). Flow fluctuations may isolate salmon redds in pools separate from the main channel. These areas will be monitored for stranding in accordance with current BOs.

Daily information on expected flows in the American River can be found on the California Data Exchange Center website at http://cdec.water.ca.gov./cgi-progs/getAll?sens_num=23 or on the U.S. Army Corps of Engineers website at http://www.spk-wc.usace.army.mil/generic/rel_rep_s.html. For information on the Stanislaus River, visit please Reclamation's Central Valley Operation Office website at http://www.usbr.gov/mp/cvo.