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Sun Enlisted to Aid Salton Sea
A System of Evaporation Ponds Is Being Tested
to Help Restore The Lake to Health.

By Jennifer Bowles
The Press-Enterprise, Saturday, April 25, 2001


NILAND
In the end, it just may be the sun's power that heals the Salton Sea.

Officials working to mend California's largest lake kicked off a pilot program Monday to see whether solar evaporation ponds can draw enough salt from the highly saline sea to return it to a healthy ecosystem.

The desert sea straddling Riverside and Imperial counties has become an important stopover for migratory birds and a fishing haven for many. However, if its salt content continues to increase -- it's already 25 percent saltier than the ocean -- certain species won't be able to survive.

The pond system, which takes advantage of gravity and solar power, would use less electricity than other salt extraction ideas being considered.

Mindful of the energy crisis, officials say if the ponds prove their worth over the next year, they could be vital to the multimillion dollar restoration project.

"The pond system looks very promising," said Tom Kirk, executive director of the Salton Sea Authority, a regional body.

An idea borrowed from salt producers, the system works like this:

Water is pumped out of the sea into the first of 10 rectangular ponds. Gravity slowly pulls the water in a zig-zag route through narrow channels connecting the ponds. As the water moves through the ponds, it evaporates and the salt concentration increases. By the final pond, the salt has crystallized and is covered over by soil.

Incoming water less salty

Water flowing into the sea is less salty than the existing lake. Extracting salts continually will eventually reduce the concentration in the sea. Mexico is building a new sewage treatment plant and the United States is creating a series of wetlands to try and filter out Mexican-generated contaminants.

Monday, Rep. Duncan Hunter and Riverside County Supervisor Roy Wilson were near Niland at the southeastern edge of the sea to help put the theory to a test.

Hunter and others turned the large circular handle of a valve to send Salton Sea water gushing from a pipeline into the sun-cracked earth of a shallow pond.

"That is Salton Sea water," Hunter, R-El Cajon, said as he watched the water flowing. "That's great."

The pilot project should extract about 700 tons of salt over the next year, said Carla Scheidlinger, project manager for Bishop-based Agrarian Research and Management Co.

On the west side of the sea at the former Salton Sea Navy Test Base, the U.S. Bureau of Reclamation is testing out a system of evaporation machines that would mist the water into the hot desert air, leaving salty chunks to fall to the ground.

In another 60 days, researchers are expected to name the preferred extraction method. While the ponds would use less energy, a full-fledged project would still cost an estimated $400 million to construct. The pond pilot project costs $775,000.

Receding shoreline

Either system would end up removing about 8 percent of the sea's water, causing the shoreline to recede slightly, Kirk said.

The sea's rescue was prompted by the late Sonny Bono, the entertainer-turned-congressman who died in a skiing accident.

The sea was once part of the Colorado River delta ecosystem, with the river occasionally snaking into the desert depression that forms the lakebed instead of the Gulf of California. Known as ancient Lake Cahuilla, it historically would evaporate away.

But that system can't work anymore because the river is heavily dammed and channeled. The sea also is filled with another 4 million tons of salt each year from waste water draining from agricultural fields in Coachella and Imperial valleys. Sewage from Mexican residential and industrial areas also drains into the inland lake.

The sea became salty because it has no natural outlet to flush it out. If its salt concentration continues to increase, many fish in the sea will die.

Already, scientists are seeing a major drop in the tilapia sports fish. Fish die-offs are a regular phenomenon at the sea during the summer and fall because of the lack of oxygen in the water.

In 1999, scientists were catching 150 fish per hour but last fall they caught one fish per hour, Ralf Riedel, a researcher at the University of Southern Mississippi, reported.

"We think there's some kind of mechanism in the sea that prevents new generations from building up," Riedel said.



Jennifer Bowles can be reached by e-mail at
jbowles@pe.com or by phone at (909) 782-7720.

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