Is Los Angeles pulling the plug on MONO LAKE?

It started here millions of years ago: The Sierra Nevada pushing up nearly 15 ,000 feet as the continent groaned and rumbled into place. Then glaciers carving out the high mountain valleys and lake basins. Finally, volcanoes spreading their lava and ash.

Over the Sierra crest, just east of Yosemite Valley, lies one of the most unusual geological formations in North America. Formed by fire and ice, the Mono Lake Basin seems stark and almost lifeless in its high desert beauty. Full of salts and alkalis, Mono Lake for years was known as "California's Dead Sea."

Weird "tufa towers" -- the result of calcium-loaded freshwater springs bubbling up through the carbonate-rich brine -- stand their silent, stony watch.

Yet, while there is not a single fish in what may be the oldest lake on the continent, doughnut-shaped Mono is teeming with life, throbbing with a fecundity that is not only highly unusual, but vital, in the claim of Western ecology. It is a rich soup of algae, brine shrimps, and brine flies to which are drawn each year millions of birds that nest and raise their young, coming from San Francisco Bay or pausing along the great migratory flyways between Canada and South America.

More than a million grebes at peak season; 100,000 Wilson's phalaropes (30 percent of the world population); 50,000 California gulls (one-fourth the world's total); teals and shovelers, sandpipers and plovers -- at least 115 bird species call Mono Lake their temporary home. Sometimes it almost seems as if you could walk the 10 miles across the lake on the birds' backs.

But there is another teeming species whose interest in the lake's waters may be threatening Mono's birds. Some 350 miles to the south, Los Angeles is drawing more and more of its fresh water supply from the mountain streams that feed Mono Lake and keep it productive.

As a result, the lake's has dropped nearly 40 feet since water diversion began in 1941. Since a "second barrel" was added to the Los Angeles aqueduct system bringing water from the north in 1971, the rate of drop has increased to nearly two feet a year.

The salinity has doubled, to the point where the shrimps may be approaching their maximum tolerance and some ducks without salt glands no longer appear here. About 10,000 acres of alkali-encrusted lake bottom has exposed a white "bathtub ring," causing air pollution that has violated state and federal standards during high winds and led at least one airline pilot to report, in error, a volcanic eruption. It is feared that the alkali dust may be damaging high mountain pines, including the ancient bristlecone pine (the oldest living thing on earth).

Of more immediate concern to environmentalists, a land bridge has formed to Negit Island, where the gulls nest and tend their chicks. This has enabled coyotes, raccoons, snakes, and other predators to cross over and decimate the rookery. Last year a University of California researcher found Negit Island scattered with broken shells and dead chicks, less than one-quarter of the colony having successfully bred.

In recent months the importance of Mono Lake has been getting greater attention as the results of man's efforts to exploit it become more obvious. The Army Corps of Engineers last year tried to dynamite a channel between the island and the shoreline, but without much success. The State of California plans to dredge a more permanent separation, but this of course will not solve the continuing drop in lake level. Nor does it address the problems of increasing salinity or air pollution from alkali dust.

The answer, according to a task force of state and federal agencies that recently reported on the matter, is water conservation in Los Angeles. Herein lies a political and legal confrontation that may continue for months and years.

Like Joy Picus, a member of the Los Angeles City Council, many Angelenos are asking, "How many people in Los Angeles are willing to drastically alter their life styles in hopes that their sacrifices will improve Mono Lake's environment, while adjoining communities continue their wasteful ways?"

Los Angeles gets 17 percent of its water and somewhat less than 2 percent of its electricity from the power generated as the water drops 6,000 feet from the Mono Basin to the metropolis.

To raise the lake level 14 feet and maintain it at its 1970 elevation of 6, 388 feet, according to the interagency task force, Los Angeles would have to reduce its Mono Basin diversions from 100,000 acre-feet a year to 15,000 acre-feet. (An acre-foot of water is 326,000 gallons.) Such a task would take 50 years and require the kind of water savings made during the 1976- 78 drought years, as well as increased reclamation of waste water.

"Mono Lake is an important symbol telling California that there are limits," says Huey Johnson, the California secretary of resources. "The state has a limited carrying capacity, and we better pay attention to the signals that tell us we are reaching it."

Two years ago, the California Department of Water Resources determined that by the year 2000 Los Angeles could be using 24 percent less water through conservation. Such a saving would require improved plumbing fixtures, more efficient watering of lawns and gardens, landscaping with more dry-climate plants, and less urban sprawl. Whether this would constitute a "drastically altered life style," of course, depends on one's point of view.

Just as controversial are the cost estimates of water conservation to save Mono Lake. The task force says the cost in 1979 dollars would be $250 million, minus $205 million to be saved in natural gas conservation (57 percent of all residential water is heated), for a net total cost of $45 million.

This would amount to 54 cents a year for each resident of Los Angeles, a sum that "doesn't seem to be too high a cost to save one of the state's outstanding wildlife, environmental, and scenic attractions," Mr. Johnson says.

City officials sputter at these figures, insisting that the real cost would be many times that figure -- perhaps $1 billion or more. They also warn that burning 400,000 barrels of fuel oil annually to replace lost hydropower and another 850,000 barrels each year to transport water from other sources would worsen the area's already grim air pollution problem.

The legal questions are just as nettlesome. Los Angeles claims a clear right to the water dating back to the 1930s, when private landholders and the federal government were talked into selling or handing over the watershed (some observers say through devious or coercive means) for the city's use. In those days, "environmental-impact statements" had not even been thought of.

While the Los Angeles Department of Water and Power today takes 100,000 acre-feet of water each year from the Mono Lake Basin, it is licensed to divert 167,800 acre-feet annually. Environmentalists worry about the fact that the water tunnels from Mono could handle 230,000 acre-feet a year.

"When they built that second tunnel, they were thinking ahead to something . . ., who knows that," says Dean Taylor, a University of California research ecologist working with the Mono Lake Committee, an environmental group formed last year.

Mono Lake supporters hope the California Legislature will move toward putting through the interagency task force's recommendations this spring. Los Angeles is sure to resist such an effort, however, and has already suggested that a five-year study be made before any move to reduce water diversions and require massive conservation.

Meanwhile, the Mono Lake Committee, the National Audubon Society, Friends of the Earth, and several Mono Basin property owners have filed suit to halt the water diversions. They are citing a historic point in common law called "the public-trust doctrine," which says in essence that nobody owns such things as air, sea, or seashore. Using this doctrine in other cases, high state and federal courts have prevented the filing of tidelands for development.

These groups contend that graining away Mono Lake to the point where it could , in fact, become a "dead sea" amounts to the same thing. The trial in this case probably won't begin for several months, just about the time the birds begin arriving at Mono Lake on their way north.

The sandpipers and the gulls and the grebes probably won't understand the legal and political maneuvering. But they may notice that the lake has become a little saltier, a bit smaller.