FRESNO – A federal judge has ruled that California's water systems threaten to push native salmon into extinction, but stopped short of ordering any immediate water cutbacks farmers said could cost millions in lost crops.

The ruling in a Fresno federal court Friday could force regulators to make changes to the way they move and use water to prioritize allowing the endangered fish to breed in the state's rivers and migrate into the Pacific Ocean.

U.S. District Judge Oliver Wanger denied environmentalists' request to store more water in Shasta Reservoir to protect spawning grounds for winter- and spring-run salmon and steelhead populations in the Sacramento River.