A coalition of water districts and agencies asked a federal judge in Fresno on Tuesday to set aside a controversial salmon management plan because it reduces water deliveries to urban and agricultural users.

U.S. District Judge Oliver W. Wanger is weighing a decision after hearing four hours of testimony. He promised a ruling by Tuesday, the date of another hearing dealing with the salmon management plan.

Among those seeking the order were the Westlands Water District, which takes in a large portion of the west side of the central San Joaquin Valley. Also among the plaintiffs were the Metropolitan Water District of Southern California, which serves 19 million people.

All depend on the Sacramento-San Joaquin Delta for water. The temporary ruling, if granted, would be in place while a more permanent measure is sought. The water agencies want the salmon management plan rewritten to allow more water to be pumped.

Federal officials had to rewrite the plan after Wanger in 2008 found an earlier set of rules did not adequately protect the endangered fish species. The rules cover salmon varieties that are protected by the Endangered Species Act.

On Tuesday, attorneys for the water agencies argued that water cutbacks when salmon are in the vicinity of the delta pumps are causing irreparable harm to water users. They also said the salmon now near the pumps are fall-run salmon -- which are not endangered -- and not the protected winter run.

"We submit there is no harm currently to the winter run [salmon], because there is no winter run," said attorney Keith Adair, who represents Westlands and San Luis & Delta-Mendota Water Authority.

Urban and agriculture users that depend on delta water say they are losing 6,000 acre-feet of water per day because of the new salmon rules. An acre-foot is about 326,000 gallons, or enough water for a family of four for a year.

But federal government attorneys and their environmental allies defended the new salmon rules. U.S. Department of Justice attorney Bridget Kennedy McNeil accused the water users of "trying to eliminate protections."

McNeil also countered Adair, saying "the winter-run [salmon] are on the move and more of them can be expected in February."

Tuesday's hearing was also slated to include the delta smelt, but Wanger delayed action because the species is not currently causing water cutbacks.