Study: Sites could have stored 120,000 AF from recent storms

A new study by the Sites Project Authority found that the Sites Reservoir could have diverted and captured 120,000 acre-feet of water in just two weeks if the reservoir had been operational from Jan. 3 through Jan. 15.

Based on forecasted flows, the analysis shows that the reservoir would continue to capture water over the next few weeks as flows continue to run high.

“This is exactly the type of scenario that Sites is being built for—short windows of extremely high flows. There is an untapped opportunity to capture and store a portion of the significant amount of flow from the Sacramento River that occurs during these rare but major storms without impacting the value of these high flows for our environment,” said Jerry Brown, Executive Director of the Sites Project Authority.

Sites Reservoir is specifically designed to divert and store water generated by storm events, like the atmospheric rivers that drenched the state in recent weeks, to increase water flexibility, reliability, and resiliency in drier years. The analysis found Sites Reservoir could have diverted 120,000 acre-feet of water—less than 4% of Delta outflow—from Jan. 3 to Jan. 15. Long-range forecasts estimated that Sites Reservoir would continue to divert stormwater through at least Feb. 15, for a total 382,000 acre-feet of water.

“The rainstorms that pummeled Northern California would have been Sites’ time to shine,” said Alicia Forsythe, Environmental Planning and Permitting Manager of the Sites Project Authority. “It would have captured a portion of the flood waters for use in future dry times by farms, families, and ecosystems, while leaving lots of water in the Sacramento River and Delta for our environment and fisheries.”

While Sacramento River flows started increasing in late December, the Project would have implemented its 7-day pulse flow protection criteria and not started diverting until January 3. The pulse flow protection criteria protects these initial high flow events as they provide value for outmigrating salmon and river ecosystems.