SACRAMENTO, CALIF., JAN. 30 -- The quality of drinking water in Southern California and San Francisco must be reduced below federal health standards, and farming in the San Joaquin Valley could be wiped out by the prolonged California drought, according to testimony before an emergency meeting of the State Water Resources Control Board.

After a second day of hearing despairing appeals for help from farmers and water-district officials, the board today put off until Feb. 7 a decision on mandatory statewide rationing and other proposals to deal with the drought, now in its fifth year.

Board officials said they need time to examine conflicting proposals and want to hear from new Gov. Pete Wilson (R), who has scheduled a statement on the drought Friday. He is expected to declare water-use guidelines but stop short of state-imposed rationing.

The hearing has produced the bleakest picture so far of what could happen in California this summer unless the state receives far above-normal rainfall in February and March, the remainder of its usual rainy season.

Analyses presented to the board showed that California's fruit and grape industries in the San Joaquin Valley could virtually disappear this summer, creating a dust bowl of 200,000 acres on normally prosperous farmland.

Assembly member Phil Isenberg (D-Sacramento) called for mandatory statewide rationing for "everyone," but most of those testifying said a single set of rules will not work because conditions vary too much from region to region.

Carl Boronkay, general manager of the Metropolitan Water District (MWD), and Anson Moran, general manager of Hetch Hetchy Water and Power, said today that reducing water quality below federal and state health standards is necessary to ensure an adequate water supply this summer.

The MWD provides most of the water for 15 million Southern Californians, about half of the state's population. Hetch Hetchy supplies San Francisco.

The reduction in water quality, which Moran said poses no threat to health "in the short run," would occur largely because the state would be relying more than usual on salty water drawn from the San Francisco Bay Delta, from which water is distributed southward to many users.

It is a measure of the severity of the shortages that proposals for reducing health standards were endorsed in principle by the State Health Services Department.

Outside the hearing room, Boronkay said that only 2 percent of the MWD's water is used for drinking purposes but that all water it sells must meet drinking-water standards. Temporarily relaxing the standards would make more water available, he said.

Boronkay also said the MWD board could decide at a mid-February meeting to begin immediately a fifth stage of water rationing calling for a 31 percent mandatory reduction. The MWD is to begin its third stage of rationing, a 17 percent cutback, Friday. The fourth stage, which may be skipped, calls for a 24 percent cut.

The crisis has been created primarily by reduction in supplies from the State Water Project, which is expected to deliver only 30 percent of normal amounts to municipal users and nothing to farmers. Boronkay said 50 percent rationing may become necessary.

A 50 percent reduction, double the present level, also is likely in the San Francisco area. Moran said that "the impact of that kind of cutback could be catastrophic" for city dwellers, farmers and wildlife.

Katy Crawford, head of the Goleta Water District, was applauded when she called upon farmers and city dwellers to put aside differences. "What I hear people saying . . . is gore someone else's ox and leave mine alone," she said, adding that this approach would prevent effective action.