Urban legislators asked the federal government Friday to cut off most of its remaining supplies for Northern California farmers in order to defend the health of city dwellers and the environment in the midst of the five-year drought.

Their pleas came as the state water board met to consider a proposal by Gov. Pete Wilson's office aimed at lowering water-quality standards in the Sacramento-San Joaquin River Delta to save water in case the drought continues into 1992.However, at the outset of the hearing the Republican governor's drought task force scaled down its proposals for water-saving measures at the delta's expense. Pointing out that early March storms have changed the water picture, it asked the board to put off a decision until early April, when the situation will be clearer.

Meanwhile, more fuel was added to the us-or-them quarrels raging over the state's dwindling water supply. They pit urbanites and environmentalists on one side against farmers on the other.

Rep. George Miller, D-Calif., called for an immediate suspension of delivery this year of 2 million acre-feet of water to agriculture from the federal government's Central Valley Project. Because of the drought, that is about one-third the amount the project allocates in years of normal rainfall.

Miller, who chairs the influential House of Representatives Subcommittee on Water and Electric Power, represents Contra Costa County, where 400,000 people get most of their drinking water from the delta. Without a flow of fresh water, sea water would back up into the delta and cause contamination.

"My constituents are being asked to endure higher levels of contaminants . . . that could cost people their health and their lives," Miller said. "It is indefensible to permit these (water) contracts to remain in force and deliver to irrigators enough water to serve 10 million people."