California is one step closer to building its largest water storage facility in nearly 50 years after a court ruled in favor of the Sites Reservoir project following a challenge by environmental groups.

A Yolo County Superior Court judge issued the 65 page ruling late last week, marking a possible end to the project’s environmental legal challenges. The relatively quick ruling stands in sharp contrast to the typically multi-year Environmental Quality Act (CEQA) process.

Gov. Gavin Newsom accelerated the project’s CEQA litigation period in November under an infrastructure streamlining package passed the previous summer. He celebrated the ruling in a news release Tuesday.

“California needs more water storage, and we have no time to waste — projects like the Sites Reservoir will capture rain and snow runoff to supply millions of homes with clean drinking water,” Newsom said.

The proposed $4.5 billion reservoir would inundate nearly 14,000 acres of ranch lands in Glenn and Colusa counties to store water diverted from the Sacramento River through new a system of dams, pipelines and a bridge.

With a maximum capacity of 1.5 million acre-feet of water, proponents say Sites will boost storage amid unpredictable climate swings. Critics warn it will threaten river habitat for fish and other wildlife and lead to minimal water storage benefits.

The lawsuit against the project was filed by a coalition of environmental groups including Friends of the River, Center for Biological Diversity, Save California Salmon and the Sierra Club.

They argued that the project’s claimed environmental impacts are underestimated and that the state failed to consider alternatives to achieving its water storage goals.

But the court found that the environmental review of the project and consideration of alternatives was sufficient, and within the jurisdiction of the Sites Reservoir Authority. The groups have 5 days to appeal the ruling issued Friday.

The court ruling marks the first time a CEQA process has been streamlined under Newsom’s SB 149, which allows the governor to certify certain projects for judicial fast tracking. Under the law, courts must decide CEQA challenges within 270 days.

Sites Reservoir is currently acquiring permits to begin construction, which is expected in late 2026. That includes a water rights process with the state Water Resources Control Board, which has not yet been scheduled for a hearing.