Scientists See a Stark Future for Mono Lake

A stark forecast of how continued water exports to Los Angeles will eliminate plant and animal life and drive migratory birds from Mono Lake was presented Tuesday in what scientists said is the most complete study ever made of the 500,000-year-old lake.

The report by the National Research Council, an arm of the National Academy of Sciences, is a milestone in the long fight between the city and environmentalists over the future of the lake, a salty body of water 300 miles northeast of Los Angeles. Water from the Sierra Nevada streams feeding Mono Lake has been drawn off since 1941 by the Los Angeles Department of Water and Power to supply the city with water.

Could Raise Costs

The dispute is of importance to water users in Los Angeles and the rest of the Southland. Los Angeles officials said that major reductions in the Sierra supply, sought by environmentalists, would force the city to look elsewhere for water, including purchasing water from another Northern California source, the State Water Project. The DWP said this more expensive water would boost water bills by $50 a year, a figure disputed by environmentalists. Such purchases, Los Angeles officials said, might also cut down water available to other Southland areas in dry years.

Martha Davis, executive director of the The Mono Lake Committee, an environmental group that has led the fight against the diversions, said that “the report confirms what we have been saying--there is a problem with the diversions and if the diversions continue we will lose the ecosystem” of the Mono Lake area.

The DWP expressed pleasure in a finding by the National Research Council that the present water level, 6,380 feet above sea level, supports aquatic life and the birds that feed on it--although the report noted that the birds fared better when the lake was at its historic high, 6,430 in 1919. Duane Georgeson, DWP assistant manager, said the report “recognizes there is no threat to the ecosystem today.”

The report, compiled by water and weather experts, ecologists, chemists and plant and animal biologists from universities around the country, will play an important role in the continuing battle over the future of the lake. Congress in 1984 turned over management of the Mono area to the National Forest Service, which, officials said, is expected to use the report as it prepares a management plan for Mono Lake and the surrounding area. The plan could affect Los Angeles water diversions.

Mono Lake, one of the oldest in North America, is a startling site to motorists along U.S. 395, with its saline water--2 1/2 times saltier than the Pacific Ocean--shimmering in the flat, barren landscape. The snow-covered Sierra peaks are nearby, contrasting with the desolate volcanic landscape around the lake. With its surface broken by oddly shaped tufa towers formed by minerals and algae, the lake looks like a scene from an uninhabited planet.

Five major Sierra creeks, Rush, Lee Vining, Mill, Walker and Parker, feed the lake. From the Sierra creeks comes Los Angeles water, part of a municipal treasure of water from the mountains and nearby Owens Valley, obtained by the Department of Water and Power’s famed chief engineer, William Mulholland, decades ago in a coup that assured the city of the water needed for its subsequent growth. Ever since, the water, which travels to Los Angeles in aqueducts, has been the source of bitter controversy.

Compiling past studies, and initiating new ones, the National Research Council scientists gave a detailed picture of what would happen to the lake if diversions continue at the 100,000-acre-feet-a-year rate of the past. The lake level now is 37 feet lower than when diversions began.

Summarizing the report’s findings, the study committee’s chairman, Duncan T. Patten, director of Arizona State University’s Center for Environmental Studies, told a news conference Tuesday at the Biltmore Hotel that if the lake drops 30 more feet, “the difference in the Mono Lake ecosystem would be striking.

“The dense populations of brine flies and brine shrimp now present in the lake would die off in large numbers due to the increase in salinity associated with a reduced lake volume and lower water levels. The lake’s large (bird) populations of eared grebes and Wilson’s and red-necked phalaropes that use the lake as a seasonal stopover point and the California gulls that nest there all depend on the flies and shrimp for food. With this resource gone, these birds would have to search elsewhere for food.

“Lower water levels would also create land bridges to current island areas in the lake, exposing nesting sites for California gulls to predators such as foxes and coyotes. At a lake level of 6,350 feet above sea level, essentially no protecting nesting areas would remain.

“Perhaps the most distinctive feature of the Mono Lake environment--its rock formations called tufa towers--would also be endangered by falling water levels. Many of the tufa towers now surrounded by water would be accessible by land, making them vulnerable to damage by rock-climbing tourists or outright vandalism. . . . “

But, Patten also warned that raising the lake level, which is advocated by the Mono Lake committee, could also hurt the towers. “Wave action from rising lake levels might topple the tufa formations,” he said.

In addition, Patten said, “the alkaline dust that lines much of the lake bottom would be further exposed by dropping water level. Consequently, the frequency and severity of dust storms would increase with significant effects on the area’s general air quality.”

Even a 10-foot drop from current levels, the scientists found, would result in a reduction of the brine fly population, which provides food for more than 100,000 phalaropes stopping at the lake during their yearly migration.

Another 10-foot drop would start cutting into the brine shrimp population, the report said, and reduce the gulls and grebes that feed on them. Only the snowy plover, which finds food at fresh-water spring areas around the shoreline, would be able to survive.

The scientists said, however, that the migratory birds would not be made extinct by the loss of the lake’s food supply, but would merely go elsewhere on their travels.

The report could not specify how fast the lake would drop because of fluctuations between wet and dry years in the area. But whatever level is set for the lake, the scientists said, a “buffer,” or leeway, of about 10 feet should be included to account for weather variables and other unexpected events.

And, the scientists declined to take a stand in the fight between the city and environmentalists over lake levels. “We’re a group of scientists, not political scientists or policy makers,” Patten said.

The report was requested by Congress because of the dispute over weighing the preservation of the lake’s aesthetic and scientific resources against the city’s needs for water.