Discovery endangers Salton Sea efforts

Deep silt in Calif. lake snarls plans to build dam that would help wildlife

December 04, 2003|By Louis Sahagun | Louis Sahagun,LOS ANGELES TIMES

SALTON SEA, Calif. - Scientists have uncovered a distressing secret about the lakebed of the Salton Sea: Portions of it are covered with a 50-foot-thick layer of silt the consistency of peanut butter.

That revelation is particularly troubling for California's largest lake, a place of promise and despair that has endured three decades of scientific study and political haggling.

The latest findings place in jeopardy a proposal by state and federal agencies to build an 8 1/2 -mile dike across the desolate and smelly lake to stave off ecological disaster. Salton Sea Authority officials say the costs of that plan could increase 200 percent, to $3 billion.

"It's a very disturbing piece of information," said Imperial County Supervisor Gary Wyatt. "Given the current political climate and budget restraints facing California, it could be hard coming up with that kind of money for the Salton Sea."

Equally worrisome is a series of mysterious biological anomalies not seen since 1989, which could have dire consequences for the 360-square-mile agricultural sump hailed by Salton Sea Authority officials as a multimillion-dollar fishery and "crown jewel of California avian biodiversity."

Perch-like fish called tilapia have failed to regenerate in anticipated numbers after a huge die-off three years ago. With fewer fish to feed on, there are fewer migrating birds. And swarms of insects called boatmen are taking wing and descending on homes and vehicles for miles around.

The Salton Sea first appeared in prehistoric times when the Colorado River repeatedly formed large lakes by filling a natural depression in the area. The most recent version was created in 1905, when the river broke through a silt-laden canal and roared unimpeded for two years into the basin near Brawley known as the Salton Sink.

Its salinity enabled oceangoing fish such as croaker, corvina, sargo and tilapia to thrive and make the area a haven for tens of thousands of birds and waterfowl.

The Salton Sea and surrounding valleys provide habitat for more than 400 species of birds - half the number of species found nationwide. One of the most important wetlands along the Pacific Flyway, the Salton Sea supports 40 percent of the nation's threatened Yuma clapper rails, nearly 90 percent of its American white pelicans and 90 percent of its eared grebes.

On a recent weekday, however, bird populations were lower than usual for this time of year, and there were only a handful of fishermen trying their luck at the 35-mile-long lake about 150 miles south of Los Angeles.

The challenges at the Salton Sea recently were compounded by an agreement to move more water from Imperial Valley to San Diego.

Under that accord, inflows to the sea would be reduced, raising concerns about dust clouds if it were to recede.

Officials had some good news to report recently, but they're struggling to explain it. Essentially, the salinity has somehow remained stable - just below the point that would be fatal for fish eggs and larvae - even though the water level has dropped nearly a foot over the past year and inflows from local farms have dumped an estimated 5 million tons of salt.

"Our best scientists are baffled by this," said Salton Sea scientist Doug Barnum. "The Salton Sea has some things going on that just don't happen in other hyper-saline environments."

Supporters of the Salton Sea had viewed the proposed earthen dike as part of a relatively cost-efficient $1.5 billion plan to create a healthier, environmentally balanced smaller lake for birds and fish.

Under the "Salton Lake concept," a significant amount of farm runoff would be diverted to a desalination plant. The treated water would then be shipped to farms for irrigation.

Clean water left over from the desalinization process would be released into the lake on the north side of the dike, reducing the salinity of the water. The south side would be reserved for shallow-water habitat, geothermal energy plants and salt ponds.

The reclaimed runoff would go to irrigation districts, enabling them to share more water with urban customers on the coast.

A preliminary analysis of the core samples, however, showed that the seismically active and gooey seabed may not be stable enough to support a dike.

"If it is as soft down there as the core samples suggest, the idea of building an earthen dike may not be as feasible as we had hoped," said Mike Walker, Salton Sea program manager for the U.S. Bureau of Reclamation.

"I'm not ready to throw in the towel," Walker said. "But we now have to talk about building a dam instead of a dike, and that means cost estimates will have to go up."

In the meantime, periodic die-offs are taking a toll on the lake's fish and birds, including eared grebes and cormorants. The U.S. Fish and Wildlife Service was prepared to take the brown pelican off its endangered species list until 1,400 died at the Salton Sea in 1996.

This year's fishery declines are among the worst ever.

"We've seen booms and busts in the Salton Sea's fishery over the years," said Tom Kirk, executive director of the Salton Sea Authority, "but never a bust like the one we're seeing right now."

Manning an airboat, biologist Tom Anderson skimmed across the lake's southern end on a recent weekday, scanning the mud banks for waterfowl and shorebirds.

"There just aren't as many birds as we're used to seeing," he said.

Making a sharp left turn, he sped toward Mullet Island, a dormant volcano encrusted with salt, guano and abandoned cormorant nests built out of cane shoots on sharp rocks.

The 3,000 birds that built them died during an outbreak of exotic Newcastle disease in 1997.

"We must save this lake," Anderson said. "California has lost 95 percent of its wetlands. That makes this body of water a vital place for birds to rest, feed and carry on with their migration journey. Without it, they might not be able to complete the trip."

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