The lawsuit said the release of 109,000 acre-feet of water to the Pacific Ocean is unlawful and unthinkable as west Valley farmers face a growing water-shortage catastrophe.
Water activists and environmentalists said a wildlife disaster would happen without the water release planned to begin Aug. 13. They said they would fight the lawsuit, which was brought by the San Luis & Delta-Mendota Water Authority and Westlands Water District.
"If they are successful, a major fish kill is likely," said Tom Stokely, water policy analyst with the advocacy group California Water Impact Network.
Federal officials at the U.S. Bureau of Reclamation said they do not comment on pending litigation.
Farm water leaders say growers already are coping with a 20% allocation from the federal Central Valley Project. The limited deliveries are the result of drought and water cutbacks to protect fish and water quality in the Sacramento-San Joaquin River Delta.
"The water shortage is causing physical, social and economic damage on a landscape scale," the lawsuit says.
Next year may be even worse, the lawsuit says. If the season is dry, west-siders might get a zero allocation. Farmers need the water involved in the planned release next week, the lawsuit said.
But that water is intended to avoid a massive fish kill like one that took the lives of tens of thousands of fall-run chinook salmon in 2002 during a similar dry year.
Drought sometimes results in high temperatures, low flows and bacteria growth that could kill salmon and other fish.
The water release from the Trinity would flow down to the Klamath River where the salmon run is expected to be very large this year.
Check back later for more on this developing story.
The reporter can be reached at (559) 441-6316, email@example.com or @markgrossi on Twitter.