OAKLAND, Calif.— Conservation groups sued the Trump administration today for pumping excessive amounts of water out of the Sacramento-San Joaquin River Delta in a way that harms imperiled fish.

The lawsuit says that the U.S. Bureau of Reclamation violated the Endangered Species Act by exceeding regulations intended to limit the Central Valley Project’s impacts on Central Valley steelhead, North American green sturgeon, and Chinook salmon.

“The Delta is the irreplaceable home of iconic and endangered California fish, like salmon and steelhead, and we can’t let Trump’s reckless pumping destroy it,” said Harrison Beck, a staff attorney at the Center for Biological Diversity. “If the Trump administration continues to pump as much water as it can out of the Delta ecosystem, we may lose these native fish forever. We can’t allow mass extinction when it’s entirely avoidable.”

Today’s lawsuit was filed by the Center, San Francisco Baykeeper, and Friends of the River in U.S. District Court for the Eastern District of California.

“The Bureau continues to violate the water export rules it proposed as recently as 2024. Those rules, which were embedded in permits to operate the Central Valley Project, are inadequate to protect San Francisco Bay’s endangered fishes,” said Eric Buescher, managing attorney for San Francisco Baykeeper. “But the adequacy of the rules won’t matter if the Bureau refuses to comply with them. The agency is behaving without regard to the law or the environment that Californians cherish and depend on.”

The Central Valley Project is a massive water diversion and export system that takes water from the Delta primarily to send to agricultural users in California’s Central Valley. This massive water system affects river flows in and out of the Delta, altering water temperatures throughout the ecosystem and blocking species’ access to important breeding habitats. Federal regulators have imposed water pumping limits to reduce harm to imperiled species but the Bureau has failed to comply with these limits.

"Every time the Bureau violates the already minimal protections that are in place for California Bay-Delta species listed under the Endangered Species Act, the agency is pushing these species that much closer to permanent and irreversible extinction,” said Gary Bobker, program director at Friends of the River. “History will not judge well those who are willing to risk consigning salmon, steelhead, and sturgeon to the same dusty museum exhibits as the passenger pigeon and the Steller's sea cow. Hopefully, neither will the courts. The fact of the matter is there’s more than enough water to protect these species and meet people's needs, if only we would manage our supplies more responsibly.”

Today’s lawsuit comes as the Bureau is poised to increase water exports from the Delta in the coming years. In response to an executive order by President Trump, the Bureau recently announced a new plan for how it will operate the Central Valley Project, referred to as “Action 5,” that would increase water extraction from the Delta despite harms to Chinook salmon, Central Valley steelhead, North American green sturgeon, and other species.