Governor signs Sen. Block bill to increase water collection, flood prevention

SACRAMENTO –The Department of Water Resources (DWR) will work to improve flood protection and water reliability by gaining more knowledge of atmospheric rivers (ARs), a little-researched weather phenomenon that supplies 30 to 50 percent of California’s precipitation under SB 758 which was signed today by the governor.

SB 758 was authored by Senator Marty Block (D-39).  Block said not enough is known about a critical source of California’s water supply, and that as the state endures a multiyear drought, California can’t afford ignorance. “Atmospheric rivers, such as ‘Pineapple Express’ storms have been responsible for breaking 40 percent of the state’s droughts since 1950,” Block stated. “Given California’s current drought, it is critical that the state have accurate science to predict precipitation patterns and make intelligent water management decisions.” Block added that scientists at Scripps Institution of Oceanography at University of California, San Diego were the driving force behind the legislation.

Atmospheric rivers are narrow precipitation regions in the atmosphere that are responsible for most of the movement of water vapor outside the tropics. A strong AR can move an amount of water vapor 10 to 20 times the average flow of water at the mouth of the Mississippi River.

SB 758 creates the Atmospheric Rivers: Research, Mitigation, and Climate Forecasting Program which would require the DWR to study the causes of atmospheric rivers and their impact on extreme weather conditions. It would also require DWR to operate reservoirs in a manner that improves flood protection and captures water produced by atmospheric rivers. This scientific forecasting can also be shared with the federal government to assist with better informed and coordinated water management.

Block’s legislation would build on a pilot project to test Forecast-Informed Reservoir Operations (FIRO) on Lake Mendocino, a vital reservoir on the Russian River. FIRO is a water management strategy that uses weather forecasts to determine when water should be released or retained depending on watershed conditions. The project is led by researchers at the Center for Western Weather and Water Extremes at the University of California San Diego and Sonoma County Water Agency.

“This bill is about good stewardship of a valuable resource. What we learn from this research could help California predict the occurrence of ARs and allow us to respond effectively in drought or flood,” Block said.

Block’s bill is supported by the San Diego County Water Authority, Bay Area Flood Protection Agencies Association, the Orange County Water District, the Santa Clara Valley Water District, and the Sonoma County Water Agency.