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Strangled By Salt
Salton Sea Needs Some Saline Solutions
Before It's Too Late

By Steve La Rue
The San Diego Union Tribune, March 30, 1994

Photos by Barry Fitzsimmons

Productive habitat: Comorants are one of the 380 bird species that make the sea one of the West's most productive habitats for migratory and short birds.

Joseph Jehl, a senior research biologist at Hubbs Sea World Research Institute, looked at the eared grebes in the Salton Sea one day in late January and knew something was very wrong.  

Small flocks of the mottled black and gray birds with piercing red eyes were sitting on the shoreline -- unusual because the birds must float and dive to find worms on the bottom.

"And they spent a lot of time drinking from the agricultural drains," Jehl said. "You normally never see them drink. They get all the water they need out of their food."

Jehl telephoned Clark Bloom, manager of the 2,500-acre Salton Sea National Wildlife Refuge. Both men knew what to expect.

"I put my people out in the field, and they verified this. We started watching a little closer," Bloom said. The first dead grebe was found Feb 17. Two days later, dead grebes by the hundreds littered the sea's coastal waters. The dying went on for a month.

In all, about 1,800 of the birds, named for the bright tufts on their heads, had died in the second major grebe die-off at the inland sea in the past three years. It wasn't nearly as severe as 1992, when 150,000 of the migratory birds perished. 

Eared grebes: Thousands of these birds mysteriously died in 1992, and another 1,800 died this year. Biologists have not found a cause.

Both die-offs appeared similar, but researchers are still not sure what caused them, or even if they were caused by nature or man.

If you have a pollution problem, it is likely to show up first in eared grebes because they seem to accumulate contaminants at a greater rate than other species," said David Klinger, spokesman for the Fish and Wildlife Service's western headquarters in Portland, Ore. 

Others say there is no evidence that grebes concentrate pollutants and insist the die-offs resulted from well known bird diseases.

In either case, the grebe deaths are yet another suggestion that the ecology of the Salton Sea, 130 miles east of San Diego, may be faltering.

Graphic by Jim Burnett

Collapse Imminent
Predictions of its ecological death have been heard since the 1950s and have been exaggerated or miscalculated.

"Now, it is 40 years later, and obviously reproduction is occurring out there," said Margaret Matsui, a researcher at Occidental College in Los Angeles who has studied the sea's fish.

But a decade of research is now strongly suggesting that the forecasts of ecological collapse at California's largest inland sea may indeed come true -- if not next year, then certainly during the lifetimes of most people living today.

The Salton Sea's large, lucrative sports fishery and its role as one of the West's most important habitats for migratory waterfowl and shorebirds may be only several years away from radical and perhaps irreversible change, naturalists warn.

Some solutions are available, but decisions to implement them must come soon, said Robyn Nagle, Riverside County representative on a new agency called the Salton Sea Authority. The problems are numerous and formidable.

Selenium, the toxic metal that washes into the sea from surrounding farms and fields, is now present in the eggs of some of the sea's 380 bird species at levels high enough to damage their reproduction.

Ever-rising salinity levels have made the sea too salty to support plankton-eating fish, an important link in the food chain, and now threaten to prevent the sea's major game fish from reproducing, other experts warn. 

If nothing changes, the sea's salt level is expected to rise to about 52 parts per thousand in 20 years -- beyond the salt tolerance of most of the major fish species now swimming in it. 

Planned water conservation projects would prevent millions of gallons of relatively fresh water from entering the sea and diluting its salt, with the result that the salt level would be pushed even higher, even faster. 

Breakdown products of DDT, the chlorine-based pesticide banned in 1972, also have been found in the eggs of a variety of Salton Sea birds. The pesticide may be thinning the eggs of black necked stilts and great egrets -- killing high numbers of chick embryos -- as it previously did with California's brown pelican and peregrine falcon.

The chemicals could have been washed into the sea when the pesticide was legal and remained in sediments. Or they may have flowed into the sea via the New River, along with Mexican agricultural runoff.

This year the Salton Sea Authority will commission $100,000 in new environment studies to devise projects that could reverse or at least stabilize the sea's rising salt and selenium levels and try to clear up the pollution. None of them will be cheap.

Rich Bird Habitat 
The Salton Sea, encompassing more than 350 square miles, is a popular fishery and a world-class bird habitat. The diversity and sheer number of birds that nest along the sea's 100 miles of coastline or pause during migrations attract more than 40,000 visitors to the Salton Sea National Wildlife Refuge each year.

"People come from not only California or the United States, they come from all over the world," said William Radke, a Fish and Wildlife Service biologist formerly at the Salton Sea National Wildlife Refuge.

At least 380 species of birds can be seen around the sea throughout the year, including about 5,000 endangered brown pelicans and about one-third of the world's population of endangered Yuma clapper rails. Peregrine falcons and bald eagles, both endangered species, are common.

American avocets and black neck stilts arrive at the sea in flocks of 10,000 at a time, and hundreds of thousands of western sandpipers stop by on their way from South America to their Canadian breeding grounds. As many as 30,000 snow geese can be seen in winter, along with 165,000 ducks of various species.

Toxic metal: Black-necked stilts arrive at the sea in flights of 10,000 at a time, but their eggs contain the toxic metal selenium as well as residues of the banned pesticide DDT, both of which may threaten reproduction.

"The breeding populations are really unmatched throughout California and the Southwest. The Salton Sea is equivalent to areas like Chesapeake Bay and areas in Alaska and Britain," said Robert McKernan, supervisor of biological collections at San Bernardino County Museum.

Deterioration of the Salton Sea environment could have a devastating effect on some of these species.

The value of the sea's sports fishery to communities surrounding the sea has been estimated at roughly $50 million per year. A 1986 state warning that pregnant women and children should avoid eating the fish because of high selenium levels has diminished enthusiasm to a degree, locals say, but the anglers still come.

Trapped Salt
The Salton Sea was actually formed by accident. In 1905, flood waters from the Colorado River washed out a water works that diverted water for irrigation. For two years, water flowed into the Cahuilla Basin, site of the ancient Cahuilla Lake, forming the sea.

Saltier than the Pacific Ocean, this sea is a closed basin where salts get in but cannot escape. The broiling Imperial Valley sun evaporates 18 percent of the sea's volume every year, but leaves the salt behind. 

Some of seas' water originates in the Colorado River, 1,450 miles away. Irrigation canals divert the river water to crops; evaporation concentrates pollutants and salts along the way.

Runout from the fields funnels into three rivers -- the New and Alamo rivers in Mexico and the Whitewater River in the Coachella Valley. Roughly 424 billion gallons of water, 4 million tons of salt and a brew of pollutants flow into the sea from the rivers every year.

Yet, compared with the strong brine already in the sea, this inflow water is relatively fresh. The young of some fish species tend to stay in these inflow areas -- where the water is sweeter -- until they can tolerate saltier water offshore, explained researcher Matsui.

Salinity in the Salton Sea has climbed only gradually -- or remained level -- at times in the recent past because the sea was allowed to dilute itself by expanding. This is not expected to happen in the future because water conservation projects could remove 20 percent of the sea's fresh-water inflows. Additionally, Mexico may purify and keep part of the voluminous flow from the New River, a source of fresh but polluted water.

Average salinity in the sea currently is between 43 and 45 parts per thousand, experts say, although 1993's heavy winter rains pumped in a jolt of fresh runoff water that will slow the rise of salinity temporarily.

Fishery Collapse
Rising salinity already has collapsed one fishery. In 1910, the sea's salt level was about 20 parts per thousand, well below the ocean's 35 parts per thousand. Fresh water species swam there in 1916, including rainbow trout, bonytail chub, razorback sucker, stripped mullet and carp, said Dwayne Maxwell, fisheries management supervisor for the state Department of Fish and Game.

"By 1929, salinity increases had eliminated all but the razorback sucker and the striped mullet, and neither of those fish were able to reproduce," he said.

Between 1929 and 1940, striped bass, silver salmon and anchovies were introduced. All died.

In the 1950s, about 30 species from the Gulf of California were introduced, and one succeeded spectacularly -- the orangemouth corvina. 

But a nine-year research project by Occidental College of Los Angeles suggests that the corvina's long reign may be nearing an end.

In laboratory experiments, Margaret Matsui varied the salinity of water collected from the Salton Sea and observed corvina reproduction at different levels. Other research focused on two other sports fish in the sea, the croaker and the sargo.

"What we found was that, although the adults are capable of reproducing at a slightly higher salinity, their eggs and larvae are not capable of tolerating salinity over 45 parts per thousand. That basically is true for all three species," Matsui said. That level of 45 parts per thousand is now thought to be approaching rapidly.

Already, the sea is too salty to support a fish species that eats the sea's prolific plankton and, in turn, provides food for larger fish, biologists say. Such fish are an important link in the food chain in ocean and other aquatic habitats.

Instead, the future of the Salton Sea's fishery appears to rest heavily on the health of the pileworm, a bottom-burrowing worm from the Atlantic coast thought to have come to the West Coast in the late 1800s when eastern oysters were introduced into San Francisco Bay 

Smaller fish like tilapia, bairdiella and sargo eat the pileworms. The corvina eat the tilapia and bairdiella 

"There has been work on salinity tolerance of this (pileworm) species, and it appears that fertilization of the eggs by sperm fails at approximately 45 parts per thousand," said Richard Thiery, an ecologist for the Coachella Valley Water District. "The pileworm is the key to the fishery. 

The sea's water is often the color of root beer, and this comes from algae that feed on the agricultural drain water that constantly runs into it. A rich food source, the algae also causes localized fish kills when it blooms and sucks oxygen out of some near-shore areas.

A far greater problem for the sea's fish and also for birds is the buildup of selenium.

In 1986, the California Water Resources Control Board formally warned that children under the age of 15 and pregnant women should avoid eating fish from the sea, and other adults should eat no more than eight ounces of these fish per month, because of high selenium levels.

The consequences of eating too much selenium can include growth and development problems among the young, and nerve, sexual, skin and stomach problems for adults. So far no health impacts in humans from eating the fish have been documented.

Selenium levels have tripled in the livers of some bird species since the late 1980s, said Joseph Skorupa, selenium expert for the U.S. Fish and Wildlife Service.  

Eared grebes pluck selenium-laced pileworms from the sea's floor. High levels of the metal could be undermining the birds' resistance to common bird diseases and could be the cause of 1992 and 1994 grebe die-offs.

But experts disagree as to whether selenium levels are rising in bird tissues.

Studies in the late 1980s also indicate that selenium levels in eggs of three species -- black necked stilts, great egrets and black-crowned night herons -- already were at high enough levels to begin causing reproductive failure and stunted growth among chicks.

Those levels were far too low to cause the kind of birth defects among surviving chicks found at the Kesterson Wildlife Refuge in the Central Valley in the 1980s.

But, "the 1980s egg selenium data may substantially underestimate current levels of avian exposure to selenium," Skorupa said.

"In a selenium contaminated environment, some of the birds never get out of the egg, and other birds do hatch, but that doesn't mean the risk is over," he said.

Selenium stunts chicks' growth and renders them less able to compete for food. "At Kesterson, 88 percent of the bird mortality from selenium was after they hatched," he said. 

Whether the breakdown products of DDT may be endangering or killing bird embryos by thinning the shells of their eggs is the subject of current research at the U.S. Fish and Wildlife Service's environmental contaminants branch in Carlsbad.

"There have been detectable levels of DDE, the most common breakdown product of DDT. Generally the first impact that you see is the eggshell thinning, and we have been looking at the eggs to see whether it is getting to that point," said Carol Roberts, a senior biologist for the service.  

If nothing changes, the sea's salt level is expected to rise to about 52 parts per thousand by about 2014, according to the Coachella Valley Water District. 

If water conservation projects succeed in reducing the inflow of relatively fresh water, salinity is expected to rise much more rapidly, to about 55 parts per thousand in 10 years, by 2004. 

In either case, the Salton Sea would then be on its way to becoming like Mono Lake, north of Bishop. Mono Lake has a salinity of 90 parts per thousand, is home to brine flies and brine shrimp, and is an important habitat for those migratory birds that eat them. 

If this is the Salton Sea's future, it will be far less biologically diverse than its past environment.

As its waters become ever-saltier, the salt-tolerant, 2-inch desert pupfish, a silvery fish that loves warm, shallow water, may become the meek, endangered species that inherits the Salton Sea.


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