The drought which last year at this time threatened to become the scourge of the West instead has proven to be its likely savior.

State and federal water officials say that the drought has provided the needed margin of safety that probably will enable the state's big reservoirs to hold the spring runoff from the massive Sierra Nevada snowpack that has built up through the winter's heavy storms.

"We would have had a terrible flood by now if the reservoirs had started the season at normal levels," said Ronald B. Robie, California director of water resources. "It just proves to me that we're dealing with a natural system, and anyone who thinks you can manage it is crazy. The engineers can't do it and neither can the lawyers. A lot of it is luck, and we've had good luck."

At the beginning of the rainy season in early December, forecasters were worrying that the drought might last a third season and were saying that even a normal year of rainfall wouldn't be enough to meet water-delivery commitments in the spring.

But within a few days of the first heavy rain the department's drought information spokesman, Bill Clark, also had been designed flood information spokesman.

"I wear two hats now, but that's all right," Clark says. "Drought and floods sort of go together."

Clark said that the 30 federal and state reservoirs that dot northern California from Mt. Shasta in the north to the Tehachapi Mountains in the south are filled to 99 percent of capacity.

They were about one-third full when the rainy season started three months ago, with 7.7 million acre-feet of water compared with a normal quantity of 20.7 million acre-feet.

An acre-foot is the amount of water that will cover one acre to the depth of one foot.

Because the reservoirs were so empty and the ground so dry, the heavy rains that triggered mudslides in southern California have causedrelatively little flooding

The main worry is that the massive snowpack in the Sierra Nevada, which usually begins to melt by April 1, will melt too quickly and trigger spring flooding.

Charles Howard, a water supply forecaster for the Department of Water Resources, says that the snowpack in the Sierra is 130 percent of normal and 155 percent of normal in the portion of the mountain range that drains into the San Joaquin Valley.

Snow depths in the mountain range from two feet in the foothills to 16 feet at Mt. Lassen, and average about ten feet, Howard said. A year ago, in the second year of a severe drought, the average snowpack was only two feet.

The big worry now is that a heavy, warm rain late in March will trigger an abnormally quick runoff.

Thelast serious flooding from melting snows in California occurred in 1967 in the San Joaquin Valley. That area, oneof the hardest hit areas in the drought, also is where the greatest threat exists is 1978.

The rains that hit California last week could turn out to have as much impact on eastern consumers as the entire two years of the drought. That's because the normal spring planting of vegetable crops was delayed by the storms. At least 7,000 acres of farmland were lost because of flooding in the Salinas Valley, which is the nation's largest producer of lettuce.

Harvests of strawberries in southern California are lagging far below normal, also, and there have been delays in citrus harvests.

"This could create a gap in production later on that will force a rise in prices," said Robert McGregor, who heads the crop reporting service for the State Department of Agriculture.

California produces half the nation's fruit crop, exclusive of citrus, and from 40 to 45 percent of the nation's vegetables.