LOS ANGELES — AFTER decades of haggling, environmentalists and the city of Los Angeles are moving closer to an agreement that could permanently protect Mono Lake, one of the country's most unusual natural resources. This week the city decided to support state legislation that would eventually require it to curtail water diversions from streams that feed the saline lake in California's Sierra Nevadas.
The action removes a major obstacle to a legislative plan to resolve one of the longest and most acrimonious water-versus-preservation battles in the arid West.
``The legislation wouldn't solve the problem,'' says Martha Davis, executive director of the Mono Lake Committee, an environmental group. ``But it would set up a framework to solve it.''
Hewn out of the Sierra Nevadas more than 500,000 years ago, Mono Lake is one of North America's oldest bodies of water and perhaps the oddest. Because it has no outlets, water from the lake can escape only through evaporation. This helps give rise to a peculiar chemistry - water nearly three times saltier than the ocean, containing 17 different minerals.
The lake supports a chain of life that begins with microscopic plants, includes brine shrimp and brine flies, and ultimately embraces a host of birds. Up to one-quarter of the world's California gulls feed here, as do prodigious populations of eared grebes, snipes, and snowy plovers.
More unusual, though, is the lake's lunar appearance. The rumpled landscape features pumice beaches, volcanic islands, and the Mono craters. There are also eerie tufa towers - chalky spires of gnarled rock that Mark Twain once compared to ``inferior mortar dried hard.''
Los Angeles has not been interested in the area for its austere beauty. Growing apace 300 miles to the south, the city has been drawing fresh water from streams that feed the lake since the 1940s.
Its interest is perhaps understandable: It is some of the cleanest water in California and cheaper to transport than some of the other supplies it draws from the northern part of the state. The water also generates electricity for the city as it flows down through aqueducts.
Yet as the city has drunk, the lake level has shrunk. Several studies have indicated that if the level drops much more, there will be noticeable harm to the area's ecosystem. The lower the lake level, the saltier the water becomes, until it will no longer support the brine shrimp and flies, which in turn would affect the birds that nest there.
Environmentalists believe the damage has already begun, while the city maintains there is a cushion to work with.
It is this deadlock that the legislation in Sacramento, now supported by both the city and environmentalists, seeks to resolve. The measures would create a $100 million state environmental water fund, some of which would go to help Los Angeles offset the costs of tapping new water and power supplies. The Mono basin currently provides one-seventh of the city's water.
Before any of the money would go out, however, the city, state, and Mono Lake Committee have to agree on a plan to preserve and protect the Mono basin. The legislation is being put forward as a lever to try to pry out a pact.
``We are hoping to help settle one of the enduring disputes in the state,'' says Assemblyman Phillip Isenberg (D) of Sacramento, who wrote the bill along with Assemblyman William Baker (R) of Danville.
The city's decision to support the bill does not signal an immediate end to the imbroglio. First, the proposals have to make it through the state Legislature; when money is involved, that is never a certainty in these austere times.
Second, the two antagonists have to work out the details of a preservation agreement before the city can get any funds. That would mean, among other things, agreeing on an acceptable lake level, something the two sides are far apart on now.
Environmentalists contend that the lake has already dropped to a point where dust storms are a problem and that a land bridge extending to one of the islands is now accessible to coyotes, which imperil bird habitats.
Nonsense, says the city. ``The ecosystem today is very healthy,'' says Dennis Williams of the Los Angeles Department of Water and Power.
An inducement to compromise could come from the courts. Environmentalists have filed several lawsuits to curtail the city's diversions, and the rulings so far have been in their favor. A key decision is expected shortly.