By Gary Polakovic
Pollution Threatens Calamity for a Great Wildlife Refuge
Perched above frothy waves that roll across the sprawling Salton Sea, crowds of gawky great egrets nest in twigs of flooded tamarisk trees, guarding clutches of eggs that will be the next generation of birds to soar above this land-locked lake.
Yet one in four eggs will never hatch and one of every three nestlings will die before it flies. Eggs are so cracked and weakened by DDT poisoning they crush under the weight of the nesting parent, killing untold numbers of chicks, according to the U.S. Fish and Wildlife Service.
The Salton Sea, one of California's richest fisheries and wildlife habitats, is fast appraoaching calamity because too much toxic pollution is being dumped into it.
The steady erosion of environmental conditions of the Salton Sea has prompted previous predictions of ecological collapse. But recent research has convinced many biologists, including the Fish and Wildlife Service's Southern California office, that toxic pollution has started to destroy life at the sea.
Dangerously high levels of selenium, another toxic agent, permeate water, mud and many animals in the sea and miles of surrounding marshland. It is a natural element more potent than arsenic and potentially lethal to wildlife. The lake bottom contains so much selenium it would qualify for disposal in a hazardous waste dump were it not underwater.
The pollutant annihilated wildlife at the 1,283-acre Keterson National Wildlife Refuge in the San Joaquin Valley nearly a decade ago and caused bird deaths and deformities in five other Western states.
Some of California's highest concentrations of DDT, a pesticide once widely used on Imperial Valley farms, have been discovered in fish and water in the Salton Sea area. The pesticide was banned 20 years ago, but residues stubbornly persist in the arid climate and scientists have begun to catalog the damage it wreaks on the sea.
If toxic pollution goes unchecked--and virtually nothing has been done to control it--a calamity eclipsing the Keterson disaster probably awaits the Salton Sea, officials warn.
"You're potentially building a super Kesterson because it is so much larger," said Ken Coulter of the state Colorado River Basin Regional Water Quality Control Board.
Irrigation practices that transformed the Imperial and Coachella valleys from a desert wasteland to a lush agricultural empire are largely responsible. Canals divert Colorado River water to crops, evaporation concentrates pollutants in the soil and farmers flush the brackish brew into three rivers--the Whitewater, New and Alamo--that whisk it to the sea, which straddles Riversie and Imperial counties.
Mexico pours a disgusting mix of contaminants into the turbid New Rivers, the most polluted waterway in the United States, which drains into an estuary at the Salton Sea National Wildlife refuge, one of the most valuable migratory bird sanctuaries in the West.
Yet, in an ironic twist of nature, the rivrs that poison the sea sustain it.
Each year 1.3 million acre-feet of much-needed fresh water flows from the rivers to the sea, diluting its salty waters. The sea, already 30 percent more saline than the Pacific Ocean and getting saltier every day, is a closed basin where salts get in but cannot escape. Cut off the inflow of tainted water and the sea, along with many of the plants and animals it supports, would die a swift death.
So much pollution has been disposed of in the sea after nearly a century of farming in that area that farmers and scientists liken it to a 380-square-mile toxic toilet bowl. Other pollutants found in elevated amounts throughout the Salton Sea ecosystem include boron, nickel, chromium, zinc, manganese and the pesticide toxaphene. Farms and industries put them there.
Numerous studies catalog the damage from toxic pollution and show:
Egret egg shells are so thinned by DDE that one fourth are crushed before hatching, said Bill Radke, a federal wildlife biologist stationed at the Salton Sea who surveyed nests in May.
"There is a lot more DDE than was ever imagined," said Dan Audet, environmental contaminant specialist for the Fish and Wildlife Service.
Sixty-two percent of sargo embryos in one sample were deformed. Some fish -- including corvina, a popular game fish, and croaker -- had eyes lacking lenses, brain irregularities and twisted bodies.
AGRICULTURAL RUNOFF IS CITED AS THE MAIN CULPRIT WHEN IT COMES TO WATER QUALITY DEGRADATION
Environmental contamination aborts an average of 6 percent to 12 percent of sportfish eggs and probably kills fish embryos soon after hatching, according to Margaret Matsui, the Occidental biologist who conducted the study.
Deformed fish were first found at the Salton Sea 40 years ago. Adult gulf croaker with grotesquely misshapen bodies and no eyes, lower jaws or gill covers were pulled from the sea in numbers that startled scientists, according to a state Department of Fish and Game survey conducted in the mid-1950s.
Deformities similar to those seen at the Salton Sea have been recorded in other heavily polluted water bodies, including the Rhine River and Baltic Sea.
Some fish in the Salton Sea are so full of selenium the state Department of Health Services warns that they are unfit as food for pregnant women, nursing mothers or children under 15 years. Other people are advised to eat no more than four ounces of Salton Sea croaker, corvina or tilapia in any two-week period.
Pollution may also have contributed to the deaths of 150,000 eared grebes, which mysteriously washed up on the shores on the sea one year ago -- one of the largest mass deaths involving birds in recent U.S. history. By comparison, about 375,000 birds perished in the Exxon Valdex oil spill off Alaska in 1989.
"There hasn't been an extensive survey for deformities. They're especially hard to find in an area as large as the Salton Sea. Based on the levels (of selenium) we're seeing, I'm sure there's a few out there."
Dan Audet, environmental contaminant specialist
for the Fish and Wildlife Service
The Value of the Sea
At risk is one of the nation's riches and most diverse wildlife habitats. About 380 species of birds inhabit the sea's warm waters and the more than 3,000 miles of marshy rivers and irrigation canals that slice like silvery ribbons through a crazy quilt pattern of farms and untamed desert. The sea is a vital stop for tens of thousands of birds plying the Pacific Flyway.
Like a shimmering blue oasis, the sea is a tourist Mecca, attracting about 300,000 visitors annually. Boaters, anglers, sightseers and bird-watchers pump millions of dollars into the regional economy.
And the lake is crucial to the $1.1 billion agricultural industry in the Imperial and Coachella valleys. About 600,000 acres of irrigated farmland sweep across panoramic desert valleys, providing 6 percent of California's food supply, much of the nation's winter vegetable crop and three-quarters of the jobs that sustain local communities.
Powerful interests, including farmers and the U.S. Bureau of Reclamation, downplay the pollution dangers. They do not believe toxic pollution threatens Salton Sea wildlife and are opposed to clean up anytime soon.
"We haven't seen any adverse impacts of any kin of contaminants out there," said John Johnson, the bureau's point person of the Salton Sea."...I don't know if we've seen enough adverse impact to warrant immediate initiation of cleanup."
SALTON SEA:Despite the evidence of damage, powerful interests oppose an immediate cleanup.
The bureau built the Colorado River dams and the All-American Canal, which provides water to farmers in the Imperial and Coachella valleys. The Imperial Irrigation District maintains the canal and the Imperial Dam near Yuma, Ariz., and delivers water to farmers. Consequently, the bureau and Imperial Irrigation District potentially face millions of dollars in liability if a Salton Se cleanup is ever required.
Conspicuously absent at the sea are widespread bird deformities, the calling card of severe selenium pollution. it is a fact not lost on the agricultural interests -- and a reality that puzzles biologists.
One possible explanation is that other chemicals blunt the most deleterious effects of selenium poisoning. However, it is equally possible that the presence of other pollutants, such as DDT, can make selenium more deadly, explained Audet, the Fish and Wildlife Service contaminant expert.
More likely, deformities have not been discovered because scientists have not throughly searched for them, he said.
"There hasn't been an extensive survey for deformities," Audet said. "They're especially hard to find in an area as large as the Salton Sea. Based on the levels (of selenium) we're seeing, I'm sure there's a few out there."
In May, scientists launched the first intensive, nest-to-nest search for bird birth defects at the sea. "There was one or two chicks that had looked suspiciously like deformities. Their beaks weren't normal" and appeared short, said Radke, the refuge biologist. However, corkscrew bills, club feet and other dramatic deformities were not found. Test results on the two chicks will not be available until late this year.
It has been 14 years since harmful levels of selenium were found in Salton Sea birds, yet no one has found a cost-effective way to stop the spread of toxic contamination. cleanup has not started nor is it planned. No money has been provided for the work either.
Alternative farming and drainage practices have been proposed to reduce pesticide-laden silt from flowing to the sea. But those measures are mimited in scope and will probably do little to remove selenium, said Coulter, the engineer at the regional water quality board.
Meanwhile, selenium and DDT continue to concentrate in the food chain. The toxic burden at the sea is so great that many of the specis tested contain contaminants in levels that exceed safety limits.
Poisoning the Food Chain
Selenium originates in ancient sedimentary rocks throughout the West. Rivers and irrigation leach the element into streams that drain into the Colorado River. it dilutes to safe levels by the time it reaches Yuma near where the All-American Canal diverts the water to Imperial and Coachella valley farms.
Every time a farmer irrigates a field, a little selenium in the water is applied to the land. Gradually pollutants build up in the soil, threatening plants. Farmers then saturate the land with water, flushing selenium and pesticides into the rivers via a complex maze of canal drains that eventually empty in the sea. Toxics build up to dangerous doses in the process.
Samples taken from a subsurface farm drain near Calipatria contained 300 parts of selenium per billion parts of water. That is 60 times greater than the 5 parts per billion (ppb) level the U.S. Environmental Protection Agency set to protect aquatic life. It is also 150 times greater than the level Fish and wildlife Service studies show selenium can accumulate to cause reproductive harm and death in fish and water fowl.
The agricultural drainage canals contain excessive pollution, too. The canals are an important source of food and cover for animals, including raccoons, catfish, minnows, ducks and fish-eating birds.
Selenium glides through the Salton Sea ecosystem with the elusiveness and mobility of a phantom. Curiously, by the time the agricultural effluent reaches the Salton Sea, most of the selenium is gone and concentrations have plummeted to about 7 ppb.
The good news is a contaminant-gobbling microbe in the Salton Sea eats selenium, quickly removing it from water. The bad news is that the microbes eventually die, sink and coat the sea's muddy bottom with a poisonous selenium sludge.
A sediment sample taken not far from the New River and near the Salton Sea National Wildlife Refuge seven years ago contained 3,300 ppb of selenium -- so toxic that if it were found on land it would have to dug up and hauled to a hazardous waste dump reserved for industries' worst chemical wastes. Sediment samples from other parts of the sea were not much purer.
Once in the mud, selenium becomes readily available to a host of plants and animals.
Bottom-dwelling creature suck the toxicant up. Pileworms on the Salton Sea floor and water bugs near the surface contain 3.1 ppm selenium. In the New River, freshwater clams contain 5.4 ppm and crayfish average 3.1 ppm.
All those animals are eaten by small fish and birds. And all those animals contain selenium near or above thresholds known to cause impaired reproduction and deformities in the offspring of the predators that eat them.
Plants take root in the tainted sediments, too. Sago pondweed growing in canals and marshes, for example, contains just 1.1 ppm selenium. Yet coots that eat its succulent tendrils contain 10 times as much.
Some waterfowl swallow sediment as grist to help them digest their food.
The selenium values get bigger and bigger further up the food chain. The process is called bioaccumulation. It occurs when an animal ingests more of a toxicant than its body can expel and then passes the load on to the predator it is unlucky enough to meet.
As a rule of thumb, forage fish and invertebrates contain two to six times more selenium than is found in their diet of algae and plants, according to the Fish and Wildlife Service.
Animals near the top of the food chain are at greatest risk.
Birds are at risk of reproductive harm when selenium in their livers measure 10 ppm to 30 ppm, according to Fish and Wildlife Service.
Eared grebes that died en masse earlier this year had an average of 30 ppm selenium in their livers. Black-necked stilts, a spindly-legged, shore-trotting bird, captured near the New River delta in 1986 contained 27 ppm selenium. The birds feed on shallow water invertebrates.
Many of the Salton Sea area fish the birds eat are loaded with selenium.
A juvenile tilapia taken near the Alamo River in 1986 contained enough selenium to make a bird or fish that ate it immediately sick. Fillets from orangemouth corvina in the same part of the sea had 20,000 times more selenium than is found in the water it swims in.
Migratory ducks that spend winters at the Salton Sea have been especially hard hit. Many of them use their bills to sift sediments in search of small aquatic creatures.
Livers UC Davis researchers collected from ruddy ducks throughout the Imperial Valley in 1979 averaged 49.5 ppm selenium -- nearly three times the amount that causes birth defects in mallard ducks. One ruddy duck in the study contained 144 ppm selenium -- close to one of the highest values known to have killed birds at Kesterson.
Northern shovelers, a duck that closely resembles a mallard, taken at the New River estuary in 1986 contained nearly three times the amount of selenium known to cause reproductive harm.
And green-winged teals, a duck similar to mallards, captured in the Imperial Valley showed 39 ppm selenium in their livers -- nearly four times the amount that caused reproductive harm in the laboratory ducks.
Kesterson birds died, bore deformed young or suffered nesting failure when selenium levels there ranged from 32 to 175 ppm.
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