Dried-up California lake gets muddy facial.

For as long as most people can remember, much of California's 110-square-mile Owens Lake has been dry as dust. In fact, the area's desiccated lake bed has been the nation's largest source of dust (SN: 10/2/01, p. 218). It's not just any dust that billows off the site, but particles of arsenic-laced silt and salt small enough to be inhaled deeply.

That's about to change, with some of Owens Lake's parched expanse slated to become mud.

About 4 weeks ago, engineers began testing 200 miles of newly installed water pipelines, a web of conduits feeding an 11-square-mile parcel of the lake bed. By year-end, water will pour from more than 5,000 pipeline outlets to keep the ground saturated. The project will require an estimated 4.5 million gallons of water annually--an amount roughly equal to the consumption of 60,000 U.S. households.

This project is the first stage of a new $250 million reclamation project intended to cut the lake's dust generation by 99 percent, according to project manager Theodore D. Schade of the Great Basin Unified Air Pollution Control District in Bishop, Calif. Eventually all of the one-third of the Owens Lake bed that has been producing dust will be treated.

Since about the turn of the last century, California has been piping mountain-stream water 250 miles south of its normal path in the Sierra Nevada. This massive diversion transformed a coastal desert into the thriving, densely populated oasis of modern culture known as Los Angeles.

However, that area's gain quickly proved the bane of Owens Lake, a body of water just downstream of the river diversion. After only a few years of the diversion, Owens Lake had vanished. Dust that eroded from the lake bed has contributed in downwind communities to frequent violations of the Clean Air Act standard for particulate pollution.

As part a 1998 settlement between Los Angeles and Schade's agency, the city's water users must finance a multiphase dust-abatement program. In the initial stage, Los Angeles must forego some water withdrawals from Owens River above the lake. The conserved water, destined for the new web of conduits, will turn a tenth of the lake bed into a permanent sea of mud.

Schade's agency will use aerial photography and satellite imagery to assess how much water to move through the system. At least 75 percent of every square mile in the current treatment zone must remain saturated for dust to disappear.

There are also plans to plant another area with a salt-tolerant native grass by 2006. First, however, this area of about 20 square miles must be rinsed thoroughly to remove much of its salt.

Although the plant, Distichlis spicata, "will grow in almost salt water," Schade notes, "the salinities we have [at Owens Lake] are three to four times the limit for this grass." The land is so salty, he says, "that no plant on the planet will grow there."

A drip-irrigation system is planned to keep the desalinized zone moist. A new drainage network beneath that planted area will collect any excess irrigation water and pipe it over to the mud area. Because that portion of the lake bed will remain free of plants, Schade says, there will be no restriction on the quality of water used to keep it wet.

Why worry about dust? Breathing particles 10 micrometers in diameter or smaller, such as those that erode from the lake bed, has been linked to respiratory illness (SN: 4/6/91, p. 212) and heart disease (SN: 7/1/95, p. 5). Indeed, while many people worry about the lake sediment's carcinogenic arsenic, inhaling huge quantities of dust, Schade says, "will kill you before the arsenic does."