Study Finds Widened Effects of Selenium

Birds in the Tulare Lake basin are being poisoned by nesting and feeding at farm water evaporation ponds containing dangerous levels of selenium, according to a new federal study released Tuesday.

Numerous comparisons between Kesterson National Wildlife Refuge and the 398-acre Westfarmers evaporation ponds near Lost Hills are contained in the Department of Interior report. It tentatively linked discovery of deformed bird embryos at the Westfarmers ponds with toxic farm drainage flowing off 6,000 acres of irrigated land nearby. The extent of the bird deformities is to be determined by further study.

Part of Survey

Levels of selenium, a naturally occuring mineral that can cause birth defects and deaths, were dangerously high in the Westfarmers food chain. The livers of American avocets, a shore bird, contained amounts of selenium twice as high as those in birds in Kesterson, the report said.

This study of irrigation water contamination in Tulare Lake basin is part of a 19-month survey by the U.S. Fish and Wildlife Service, Geologic Survey and Bureau of Reclamation.

“Irrigation drainage is causing or has the potential to cause harmful effects on human health or fish and wildlife resources, or to significantly impair beneficial water uses, in each of these areas,” according to a Department of Interior memo. The agency called for a more in-depth look at the contaminated areas.

The Tulare Lake basin study surveyed the Pixley National Wildlife Refuge in southern Tulare County; Kern National Wildlife Refuge, about 40 miles north of Bakersfield, and the Westfarmers ponds, five miles west of the Kern refuge.

Under close study was the mineral selenium, which is vital in small quantities for healthy animal metabolism but is toxic in larger doses.

The most graphic example of selenium contamination is at Kesterson, west of Merced, which began receiving mineral-laden drain water from western Fresno County farms in the late 1970s. Accumulation of high levels of selenium was blamed for widespread bird deformities and deaths at the refuge. A multimillion-dollar waste cleanup plan is pending.

The Interior Department report gave the Pixley and Kern refuges a generally clean bill of health, showing very low levels of selenium or pesticide contamination.

Pesticide Residues

“Few pesticide residues were detected in bottom material and even fewer were found in water samples,” the report said. Diazinon, an insecticide, as well as atrazine and proetryne and 2,4-D, herbicides, were detected in low concentrations, the report said.

The study said selenium levels in some of the Westfarmers ponds were as high as 350 milligrams per liter, about 10 times above the Environmental Protection Agency’s standard to protect fresh-water aquatic life.