Report: Forecast-Informed Reservoir Operations can reduce flood risk

Using Forecast-Informed Reservoir Operations, or FIRO, to manage reservoir operations at Lake Oroville and New Bullards Bar Reservoir can further reduce flood risk for communities along the Yuba and Feather rivers during extreme atmospheric river storm events and potentially benefit water supply during drier periods.

That is the sentiment coming out of a new report by the Center for Western Weather and Water Extremes (CW3E) at Scripps Institution of Oceanography. FIRO uses improved monitoring, weather, and runoff projections to build more flexibility and efficiency into reservoir operations.

In the largest FIRO assessment to date, the Department of Water Resources and Yuba Water Agency partnered with CW3E and the U.S. Army Corps of Engineers’ Engineering Research and Development Center to evaluate if FIRO could be implemented at both reservoirs to reduce downstream flood risk without negatively impacting water supplies.

Using historical forecasts, reservoir storage and river flow data, scientists found that FIRO, combined with a planned second spillway at New Bullards Bar, could provide additional flood storage capacity in the Yuba-Feather system and reduce downstream peak flows during prolonged storms like the 1986 and 1997 floods that devastated Yuba County.

FIRO can also improve California’s ability to provide a reliable water supply for communities and agriculture during high-flow events.

“This is a critical step towards making more floodwaters available for groundwater recharge when we see extremely wet storms,” said DWR Director Karla Nemeth. “FIRO drives tighter coordination between reservoir operators and water districts downstream, creating opportunities to use reservoir releases to build up our groundwater reserves for dry years.”

To fully realize the benefits of FIRO, Yuba Water is planning operational changes, continued atmospheric river monitoring, and the construction of a new Atmospheric River Control (ARC) Spillway at New Bullards Bar. The second spillway will have gates 31.5 feet lower than the dam’s existing spillway gates, allowing the agency to release water before large, threatening storms hit, when there is enough downstream channel capacity to handle the flows.