California under pressure to curb nation's largest PM source California faces the threat of fed­eral sanctions for its failure to adopt a plan that would curtail severe dust problems from Owens Dry Lake in the southeastern part of the state. The lake is the largest single source of particulate air pollution (PM-10) in the nation.

On Aug. 22, EPA notified Cali­fornia that it faces penalties be­cause it failed to submit an ac­ceptable remedial plan by last February. Sanctions, including a loss of federal highway funding, begin Feb. 20, 1999, unless EPA receives an acceptable plan be­fore that deadline. "The people of Owens Valley have already waited too long to breathe clean air," said EPA Regional Administrator Felicia Marcus.

Los Angeles began draining Owens Lake in 1913 when an aqueduct was built to provide water to the growing city. The 110-square-mile lake was almost fully drained by 1920 and has re­mained a source of dust ever since. Although deserts are often the source of blowing dust, Owens Lake is clearly the worst problem ever created by the diversion of water. It is estimated that the lake kicks up 4 million tons of dust particles annually, according to the Desert Research Institute. Also, the dust is tainted with nickel, cadmium, and arsenic.

Studies have shown that com­munities as far as 50 miles from the lake have PM-10 levels that exceed current federal air quality standards. The lake is also one of many reasons that Southern Cali­

fornia has failed to meet Clean Air Act standards in the 26-year history of the law.

A complex and potentially costly solution crafted earlier this year by the local Great Basin Uni­fied Air Pollution Control District would concentrate on an area roughly 35 square miles to reduce the dust to acceptable levels. The remedial strategy includes gravel coverings, vegetation, and shallow flooding of portions of the now-dry lake. The planted vegetation would be indigenous: cattails, sedges, and saltgrass. Areas not flooded would be covered with a four-inch layer of gravel to minimize dust-contributing salt crusts, which form when water evaporates.

All of the proposed control strategies have been tested exten­sively on a pilot basis. Great Basin officials previously tested water sprinklers, chemical dust sup­pressants, surface compaction, and sand and brush fences and deemed them ineffective in re­ducing the airborne dust.

To flood the lake, Los Angeles would be forced to give up about 51,000 acre-feet of water per year—about 13% of the 395,000 acre-feet it now imports from the Owens Valley region. The cost could be as high as $250 million, with annual maintenance of $26 million. Computer models show that the remedial program would cut emissions by 99%, according to Great Basin's plan.

But the plan would also force Los Angeles to conserve water or find new sources in a region al­

ready pressed to meet its needs. The city already faces reductions in its water supply, following a 1995 agreement to restore water levels in the ecologically troubled Mono Lake. The once-pristine lake lost half its volume and re­corded a doubling of its salinity after Los Angeles began drawing water in 1941.

Although the California Air Resources Board and the local air pollution control district have been studying the issue for years, Los Angeles has resisted any re­mediation that would have an impact on its water supply.

Jerry Gewe, Los Angeles direc­tor of water sources, said the city may be willing to sign on to the Owens Lake plan, but only if it is given sufficient time to find new sources of water. He also said groundwater sources may exist that could be used, in part, to help flood the dry lake. "We are cer­tainly hopeful we can reach a com­promise, but only if it will allow for a phased implementation," he said.

Duane Ono, a Great Basin dep­uty air quality officer, said the remedial plan has been submitted to the California Air Resources Board for approval. The state board must sign off on the plan before it can be submitted to EPA. Ono acknowledged that difficult nego­tiations remain between the city and the two air quality agencies. "We are trying to find a compro­mise, we are trying to avoid litiga­tion," said Ono. "But will we be successful? I just don't know." —RAE TYSON

Flooding portions of Owens Dry Lake to stop dust storms is one of the steps California would have to take to meet federal air quality standards for PM-10. (Courtesy Great Basin Unified Air Pollution Control District)

5 0 4 A • VOL. 31, NO. 11, 1997 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS