Water Rationing Is Blamed on Fears of 5th Year of Drought : City Hall: Bradley’s decision comes despite more-than-adequate supplies for the current year. The idea is to “bank” water for 1991.

Mayor Tom Bradley’s decision to impose water rationing this year was driven more by fear about supplies in 1991 than about any shortages this summer, city water officials and aides to the mayor said Thursday.

According to city engineers, there is enough water to satisfy projected demands through the end of the year without any conservation, let alone rationing.

The Department of Water and Power projects that the city will require about 710,000 acre-feet of water this year. At current projected levels, supplies will amount to about 720,000 acre-feet.

The city expects to obtain 170,000 acre-feet via its aqueduct from the Owens Valley in the eastern Sierra Nevada. An additional 100,000 acre-feet can be pumped from San Fernando Valley ground-water supplies, and the balance, about 450,000 acre-feet, has been ordered from the Metropolitan Water District.

Even though the city’s water supplies are expected to be adequate for the remainder of 1990, the mayor feared that a fifth straight drought year in 1991 could put the city in deep trouble, said aides who requested anonymity.

Bradley’s rationing decision, according to City Hall staffers and DWP officials, was based on long-term public policy concerns.

The mayor, who earlier had appealed for voluntary conservation, announced on Wednesday that he wants mandatory water rationing to reduce consumption by 10% from pre-drought 1986 levels. The measure must be approved by the City Council.

If Bradley’s strategy works, Los Angeles will have substantial supplies of water in reserve to carry into next year, city officials say.

Even without the expected savings from rationing, the city does not expect to draw down its long-term water reserves.

Jim Wickser, assistant general manager of the Department of Water and Power, said he expects to maintain a normal level of reserves in San Fernando Valley ground water and the major reservoir at Crowley Lake. Crowley Lake is now at 50% of capacity, holding nearly 100,000 acre-feet of water, or enough to supply 200,000 families for a year, according to Wickser. Officials said that some level of reserve is always necessary.

If the city successfully conserves 10% of this year’s supply, Wickser said the DWP could “bank” 70,000 acre-feet of water--enough to supply 140,000 households for a year--and add it to the reserve.

The Metropolitan Water District, which supplies Los Angeles with about 60% of its water, also is bracing for an unprecedented fifth year of drought by trying to maintain its reserves.

“That’s part of the strategy,” said Duane Georgeson, assistant general manager of the MWD.

MWD is counting on its member agencies to cut their usage by 10% this year. If they do, the district would have about 800,000 acre-feet of water stored for 1991, Georgeson said. That is a healthy level for a normal year, let alone a drought year when the snowpack is only 50% of normal, he said.

Based on such projections, both the DWP and MWD so far have stopped short of recommending mandatory rationing.

But Bradley, in announcing his plan on Wednesday, said he had all the information he needed to make the decision.

The engineers had always said a four-year drought was unlikely, if not unprecedented, in California. But then it happened.

The snowpack in the Sierra Nevada is down to about half of normal this year, reducing the volume of spring runoff to both the DWP’s sources in the Owens Valley and the MWD’s sources in the Sacramento River Delta.

Light winter storms in the Rockies have reduced flows in the Colorado River to less than half of normal, cutting deeply into the MWD’s second source of water.

A fifth year of drought in 1991 would be even more devastating. The cumulative effects of the drought further reduce runoff from the snowpack.

And continued drought means Los Angeles will be unable to import any of the 100,000 acre-feet of water it usually takes each year from streams in the Mono Lake area of northeastern California.

Courts have ruled that Los Angeles illegally lowered the level of Mono Lake and eliminated fish life in four streams by its water diversions, which began in the 1940s. Los Angeles is now under court order to release enough water to protect both the lake and the fish, which have returned in small numbers.

At a hearing in South Lake Tahoe this week, the state Department of Fish and Game said that more than 70,000 acre-feet of water will be needed every year for trout to thrive in the four key Mono Lake streams.

That would put a permanent dent in the water Los Angeles takes from the Mono Lake area, except in very rainy or heavy-snowfall years.