LOS BANOS, Calif. — Experts agree that toxic levels of selenium still threaten millions of ducks and other wildlife on the grassy wetlands in west Merced County four years after hundreds of deformed, dead and dying birds were found in the Kesterson National Wildlife Refuge, north of here.
But the governmental agencies responsible for protecting the environment and cleaning up what amounts to a massive toxic spill in the Kesterson area can't agree on how best to remove the selenium, an element that is beneficial to life in trace amounts but highly toxic in even slightly higher concentrations.
The 5,900-acre refuge is owned by the U.S. Bureau of Reclamation and operated by the U.S. Fish and Wildlife Service. Its marshy wetlands have been flooded by agricultural drain water from massive federal irrigation projects farther south in the San Joaquin Valley. The selenium-laden waste water, transported 70 miles north through the bureau's San Luis Drain, formerly emptied into the 1,283 acre Kesterson Reservoir, a network of 12 shallow ponds within the refuge.
On Feb. 5, 1985, the state Water Resources Control Board ordered the refuge closed and gave the bureau three years to clean up the massive contamination. The bureau's cleanup plan has been submitted to the board and a public hearing has been scheduled for Jan. 26 to air the growing controversy surrounding efforts to detoxify the refuge.
While government experts argue over Kesterson's future, new evidence is being gathered indicating that the selenium problems there may only be the tip of the iceberg, the most visible example of widespread selenium problems that affect another 72,000 acres of wetlands used by 1.5 million ducks and 60,000 geese as a winter range in western Merced County.
'Nesting Failure' Found
Called the "Grasslands," this area contains 160 private duck clubs, private livestock ranges and three additional state and federal wildlife refuges. These lands receive water from natural surface flows and the agricultural drain waters collected in canal systems by a dozen or more irrigation and water districts in the area.
Elevated levels of selenium are being found in aquatic insects and other basic elements of the wildlife food chain, a fact that wildlife scientists say has contributed significantly to "an almost total nesting failure" among tricolored blackbirds, a species found primarily in the Grassland area and now designated as a candidate for the endangered species list.
Only 100 fledgling blackbirds were observed by researchers who counted 266 dead chicks and estimated that 82,000 eggs and chicks were lost in 1986, according to the state Water Resources Control Board. A board staff report cited these figures as examples of how seriously selenium was affecting the area. "It is almost certain that the deaths were due to selenium toxicosis (poisoning)," the report concluded.
Because of such findings, the cleanup at Kesterson has taken on added significance. The work here is being considered a proving ground for both federal and state regulators responsible for protecting the environment.
The cost of cleaning up Kesterson could run as high as $24.6 million, if the bureau has to remove all the contaminated reeds, brush and other vegetation and scoop up half a million cubic yards of selenium-laden bottom sediments, a price that budget-conscious bureau managers are reluctant to pay.
Instead, Kesterson cleanup director Susan Hoffman said the bureau is trying what it calls its "wet-flex" plan, a relatively cheap and simple cleanup method. If that method does not work, the bureau would proceed to more expensive and complicated methods. This phased approach--which could take up to five years--has been criticized by state and federal wildlife experts. The effectiveness of the untried plan is also being questioned by the state Water Resources Control Board's staff.
The bureau has already begun implementing its plan by flooding eight of 12 Kesterson ponds with a layer of uncontaminated water that bureau experts say will "seal" the selenium into the muddy sediments. According to the environmental impact statement, this method "may prevent selenium . . . from moving into the ground water and wildlife food chains at unacceptable levels."
The $3.8-million-a-year first step is based on continuing research by the University of California's Lawrence Berkeley Laboratory that indicates the selenium in the flooded ponds will disappear from the wildlife food chain within one to five years. Bureau officials say selenium levels in wildlife are already dropping since the San Luis Drain was closed.
"Selenium, if you keep it wet and away from oxygen, will turn into its elemental form and be bound up on soil particles so that it will not be biologically available," said chemist Oleh Weres, a Lawrence scientist.
Ponds Will Be Plowed Under