Attorneys for some of the nation's largest farms and Southern California cities had asked for a preliminary injunction that would lift a set of water restrictions in the Sacramento-San Joaquin Delta through mid-June.
The pumping limits were put in place to protect threatened salmon, steelhead and other fish as they swim through the freshwater delta into the Pacific Ocean. But farmers argued the cutbacks caused millions of dollars in crop losses and other environmental damage.
After hearing hours of testimony Tuesday, U.S. District Judge Oliver Wanger lifted the restrictions for three weeks, freeing up extra water supplies growers said would bring acres of melons, lettuce and other crops back into production in time for the summer harvest.
"I could not be more thrilled," said Tom Birmingham, general manager and general counsel to the Westlands Water District, whose members include some of the giants of agribusiness. "If there is surplus water in the system that can be taken without doing harm to the fish, it is nonsensical to think we would let that flow out to the ocean."
Environmentalists and federal scientists said the decision risked endangering sensitive species that have already been pushed to the brink of extinction, and would keep West Coast fishermen out of work.
"We're very concerned for the fish," said Erin Tobin, an attorney with Earthjustice. "This time of year is crucial to protect the late-migrating salmon, especially when the species is already doing so poorly."
The sweeping San Joaquin Valley grows most of the country's fruits and vegetables, but three years of drought and water cutbacks from the state's freshwater estuary have hammered the region, causing drastic job losses and other economic woes.
Even as recent storms have replenished reservoirs, pumping has been curtailed to protect juvenile spring-run Chinook salmon as they navigate the treacherous pumps and canals linked to the delta - the heart of the state's water delivery system that supplies cities and farms.
West Coast fishermen argue the limits are necessary to save their dwindling catch, and say the collapse of one of the region's biggest wild salmon runs two years ago foretold the extinction of related species.
Wanger said the environmentalists and the federal government could return to court to ask for the limits to be reinstated if more threatened salmon or Central Valley steelhead are found around the massive pumps or scientists find other evidence that fish are being harmed by more pumping.
The judge also ruled last week that the federal government did not properly develop a management plan that restricted water exports to protect salmon, steelhead and other fish.
Wanger is expected to issue a ruling on a similar lawsuit that seeks to block a 2008 management plan that imposed pumping restrictions to protect a tiny fish called the delta smelt, which also is listed as threatened under the Endangered Species Act.