The flow out of Folsom Lake into the lower American River was more than doubled Monday night by the Bureau of Reclamation, which manages the lake's water storage capacity.
The move is to create space in Folsom Reservoir for projected runoff from the Central Sierra where the snowpack is more than four times greater than at this time last year, according to a Reclamation news release.
Lights flashed and alarms sounded at the Nimbus Dam below the lake at 5 p.m. signaling the increased flow.
According to Reclamation's plan, the flow is to increase gradually from 3,000 cubic feet per second (cfs) to 7,200 cfs gradually over an 8 hour period in hourly increments of 500 cfs.
"After two days at this rate, flows will be gradually ramped down as we continue to monitor and manage storage in the reservoir," stated Reclamation's news release.
Monday's Folsom Reservoir level was 65% of total capacity, 131 percent of the 15-year average for late February.
The Water Control Manual for the lake, a set of federal rules dictating how much and when water is released, was written in response to the floods of 1986 and 1997. That manual is in the process of being updated along with the construction of a new Folsom Dam that will open in 2017. In the meantime, Reclamation releases water based on the current federal rules.