Feb. 16—According to a new analysis by the Sites Project Authority, the proposed Sites Reservoir would be 80% full after recent storms had the long-planned project been in place.

In development for several years, Sites Reservoir is considered one of the largest reservoir projects in California. It is an off-stream water storage project that will be situated north of the Sacramento-San Joaquin Delta in Sites Valley, 10 miles west of Maxwell where Colusa and Glenn counties meet.

Officials said once built, the reservoir will capture and store a portion of stormwater from the Sacramento River — after all other water rights and regulatory requirements are met — and release water to benefit communities, farms, businesses, and wildlife across the state during drier years.

Officials have previously said it could provide 1.5 million acre-feet of additional water storage capacity in an attempt to offer unique water supply and environmental benefits during these dry periods, including extended droughts. Officials this week said if the reservoir were in operation, the 2023 and 2024 storms combined would have yielded about 1.2 million acre-feet of water.

“These latest storms show the need for Sites Reservoir to capitalize on California’s rainy season and store excess stormwater for the betterment of communities, farms, and the environment,” Fritz Durst, chairman of the Sites Project Authority Board of Directors, said in a statement. “While the exact amount of water will vary from year to year, we need to be prepared to capture water from major storms when they happen and save it for the next inevitable dry period. With hotter and drier weather threatening California’s water supply, we have no time to waste.”

Sites Reservoir, which is being designed to capture and store water generated by extreme storm events, has been projected to cost as much as $4.4 billion. Already, the project has received millions in funding from the federal government, with a total of $233.7 million in federal contributions made as of November 2023.

In November 2023, the Sites Project Authority certified its final environmental impact report and approved the Sites Reservoir Project. With the certification, the Sites Project Authority was able to move the project forward through its final planning stages and on to construction, officials said.

“Over the last six years, we conducted one of the most comprehensive environmental analyses ever done for a water supply project to design a project that can meet the needs of California’s communities, farms, and environment,” Durst previously said. “Sites Reservoir is a new way of managing water designed to provide resiliency and reliability amid our changing climate.”

The final environmental impact report evaluated the environmental effects and proposed mitigation measures associated with construction and operation of the Sites Reservoir Project, the Appeal previously reported. It included updates to previous environmental impact reports to reflect changes in the project and address public concerns. The report contained revised modeling results, but no new or substantially greater impacts were identified, officials said.

Some environmental groups — Friends of the River, the Sierra Club, and the California Sportfishing Protection Alliance — were opposed to the Sites Reservoir Project’s approval. The final environmental impact report was reportedly approved by the Project Authority two weeks after giving the public access to the documents.

These three conservation groups formed a coalition, claiming the project does not meet the criteria for Senate Bill 149, which was signed earlier in 2023 in an effort to streamline projects such as Sites Reservoir to avoid months or years of litigation delays through the California Environmental Quality Act, the Appeal previously reported.

The coalition also claims that Sites Reservoir would have significant impacts to disadvantaged communities, it would continue to damage the Sacramento River and San Francisco Bay-Delta ecosystems and has shown that it would not prioritize water for ecological benefits.

“Despite the appearance of unanimity and kind words about teamwork and environmental benefits in today’s meeting, the environmental community continues to oppose the Sites Reservoir project due to countless harms,” Friends of the River Policy Director Keiko Mertz previously said. “The project is an expensive boondoggle that won’t provide net environmental benefits or meaningful increases in water supply. While today’s vote was never in question, it is still disappointing to see this project escape public scrutiny at every turn.”

The coalition said it would continue to work to stop the “environmentally destructive Sites Reservoir Project and offer sustainable solutions for California’s water future.”

According to recent analysis by the Sites Project Authority, Sites Reservoir could have “safely” diverted a “relatively small” part of Delta outflow during recent winter storms, leaving a “significant natural flow” in the Sacramento River and the Delta for ecosystem needs.

“Estimates show that during these most recent two months of 2024 storms and projecting diversions through mid-March, approximately 450,000 acre-feet could have been stored so far in 2024,” officials said. “There are still about two months of wet season remaining with the potential to raise water levels even more. A single acre-foot of water is enough to exceed the average annual indoor and outdoor water use of one to two California households, according to the Water Education Foundation.”

Officials said the study showed that after all other needs were met, Sites Reservoir would have been able to store excess water while meeting the project’s protective diversion criteria.

“This real time observation is consistent with the Authority’s robust water availability analyses, as presented in the Sites water right application currently being considered by the State Water Resources Control Board, where multiple analytical methods used predicted there is enough water for Sites, the environment, and existing senior water right holders in the Delta Watershed under a variety of water supply scenarios, now and in the future,” officials said.

Despite concerns from environmental groups, officials claim the project will not harm the environment while focusing on water availability.

“The entire Sites team is invested in ensuring there will be water for Sites Reservoir while not harming the environment, which is why we conducted the most extensive water availability analysis in California history for this project,” Jerry Brown, executive director of the Sites Project Authority, said in a statement. “The real-time data matches what the models are saying and demonstrates Sites can viably capture and store water for drier periods. We are confident in our analysis and are asking the State Water Resources Control Board to expeditiously come to the same conclusion and issue our water right permit, so we can get busy building this new, badly needed facility to provide more water certainty for all of California.”