By Mark Henry
The Press-Enterprise, November 20, 1998
U.S. Filter proposal might remove chemicals, but result could increase salt levels and water temperature.
At the Salton Sea, no one is sure which is worse -- rising salt levels or the tons of harmful chemicals that pour into the fragile ecosystem each year.
Now, a Palm Desert-based company says it has the ability to recycle farm water for irrigation and remove pollutants before they reach the sea.
Although the proposal looks promising for water users, the effects on the the Salton Sea might not be so beneficial, even with the removal of the chemicals.
The plan could cut flows to the sea in half eventually, thus reducing its size, yet further intensifying salinity and raising water temperature. The latter could trigger more fish die-offs.
U.S. Filter Corp., the world's largest water service company, says it can build a recycling plant to reclaim large amounts of farm runoff that normally flow into the Salton Sea. The plant could recycle enough farm runoff to replace water destined for thirsty San Diego County, said H. Martin Jessen, U.S. Filter's senior vice president of governmental affairs.
For now, U.S. Filter is running a small pilot project near the Alamo River between Brawley and Calipatria in Imperial County. The primary goal is to make the quality of recycled agricultural runoff as good as the Colorado River water now used for irrigation. The project started in late August and will continue through at least the end of the year.
If tests prove successful, U.S. Filter hopes to build a large plant that could recycle up to 600,000 acre-feet of water annually along the Alamo River. Most of that would evaporate in farm use rather than flow back to the sea. The reduction would amount to nearly half the farm runoff now flowing into the sea each year. An acre-foot of water is 326,000 gallons, roughly enough to cover a football field in a foot of water.
About 1.3 million acre-feet of water now flow into California's largest lake. Reducing that amount by almost half would lower the sea level by 25 feet after 50 years. That would expose 135 square miles of lake bottom, according to Richard Thiery, a biologist for the Coachella Valley Water District.
A water recycling plant could create up to 400 jobs in the Imperial Valley, U. S. Filter reported. The company envisions the district selling the recycled water to farmers as it currently sells Colorado River water.
On a global scale, the technology could be used to clean up polluted agricultural runoff in countries around the world, according to U.S. Filter.
The Salton Sea has formed and evaporated several times. The current sea was formed by accident in 1905 when a Colorado River canal broke and poured water into the basin. Since much of California's wetlands has been lost to development, the sea has become an important stopover for migratory birds, including the endangered white pelican.
The sea has no outlet and depends almost entirely on agricultural runoff. In recent years, it has been the site of massive fish and bird die-offs.
Jessen said the U.S. Filter project alone will not save the inland lake, which straddles Riverside and Imperial counties. The project has the potential of removing two-thirds of the harmful selenium, nitrates, pesticides and other harmful elements now flowing into the sea, the company said.
But it will not reduce salinity, viewed by some researchers as the most pressing problem at the sea, he said.
"The concentration of salts in the water reaching the Salton Sea will be higher," Jessen said. "The trade-off is, all of the other pollutants will be out of it." The sea already is saltier than the ocean, and computer models show fish will not be able to survive in the sea in another 12 to 15 years.
Diverting farm runoff from the sea will shrink the sea, making it even saltier, said Stuart Hurlbert, a biologist and director for the Center of Inland Waters at San Diego State University.
But any plan that can remove harmful selenium and nitrates from farm water before it reaches the sea is intriguing to wildlife officials
"The sea is like a giant fish tank in dire need of a good cleaning," said Steve Horvitz, longtime superintendent of the Salton Sea State Recreation Area.
Horvitz believes nitrates from fertilizers are the most immediate threat to the sea. Nutrients from fertilizers causes algae blooms, he said. The algae come to the surface and die. It creates a sulphur stench, pulls oxygen out of the water and causes massive fish kills, he said.
At the same time, shrinking the sea would increase salt concentrations, he said. A shallower sea also could increase water temperatures from current late summer highs of 93 degrees, Horvitz said. Warm water makes it harder for fish to breathe because oxygen dissolves less easily as temperatures rise, he said. It also could promote algae blooms, he said. Each change in the ecoystem can upset the balance, he said.
U.S. Filter understands that restoring the sea will take a separate project to stabilize salt and sea levels, Jessen said.
A multiagency task force has been studying ways to make that happen. One option calls for a system to pump in ocean water from the Sea of Cortez to stabilize salt and water levels.
A large U.S. Filter recycling plant would allow the Imperial Irrigation District to transfer water to San Diego County without reducing the amount of water available for Imperial Valley farmers, Jessen said.
The Imperial Irrigation District reached a tentative agreement with the San Diego County Water Authority in April to transfer up to 200,000 acre-feet annually. It would start with 20,000 acre-feet per year and increase by that amount every year, reaching 200,000 acre-feet after 10 years.
But the deal depends in part on the outcome of a study on how the water transfer will affect the environment in Imperial Valley.
The Imperial Irrigation District is monitoring the U.S. Filter program as one of several possible ways for farmers to conserve water, said district spokesman Ron Hull.
"The experimental plant is online and it seems to be working well, but there's still a lot of hurdles to go," he said.