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April 16, 2013

The Kesterson National Wildlife Refuge

Filed under: Uncategorized — admin @ 10:18 pm

The Kesterson National Wildlife Refuge, established by the Bureau of Reclamation in 1970, is a 10,621-acre artificial wetland environment created using runoff from California’s Central Valley (Zahm).  The Refuge saw a decrease in species diversity and an increase in deformity unusual for a marsh environment, prompting the U.S. Fish and Wildlife Service to conduct tests on minerals in the soil (Vencil).  The studies ranged from analyzing the effects on plants, aquatic invertebrates and fish in the reservoir, and their subsequent effects on aquatic birds as well as bird eggs and tissues, to determining the chemicals’ effects on the birds’ reproductive systems (Ohlendorf).  They found unusually high levels of selenium in mosquito fish (Vencil).  This was also the chemical with high enough concentrations to affect the Kesterson birds.

In hindsight, selenium was a foreseeable problem.  The mineral originates in the pyrite of the Cretaceous marine sandstone and siltstone shale deposits in the coast range and under valley soils (Vencil).  Because rainfall is light, the deposits remain in the soil.  Weathering, erosion and irrigation leach minerals such as selenium but because western soil and water are alkaline, leached selenium takes the form of selenate.  Selenate tends to accumulate in estuaries and be easily taken up into the foodchain.


The San Joaquin Valley soil had poor drainage because it was underlain by the Corcoran Formation, an impermeable clay layer (Garone).  The land needed subsurface drains to collect the saline groundwater and carry it away from the irrigated areas.  The Bureau of Reclamation and the Department of Water Resources (DWP) planned the development of a master drain, but since the DWP pulled out of the project (because Reagan, Governor of California, didn’t support it), it didn’t get built.  Consequently, in the early 1970s, the U.S. Bureau of Reclamation (USBR) started to build the San Luis Drain on its own to provide irrigation water to farmers in the Westlands Water District (Garone).  Federal budget constraints and effective political opposition prevented completion of the all of the drain; hence the drain ended at the Kesterson Reservoir with the purpose of providing habitat for wildlife and cleaning the water.  As a result, the Bureau changed Kesterson’s status from a regulating reservoir to a terminal holding reservoir, which would store and concentrate drainage water (Garone).


The California State Water Resources Control Board was concerned about the potential effects on wildlife from the chemicals in the drainwater, so it proposed that the USBR conduct studies at the Kesterson Reservoir.  However, because the USBR was not obligated to study wildlife, it didn’t fund the studies, leaving the U.S. Fish and Wildlife Services to fund the studies on its own.  The initial focus of environmental impact testing was on salinity and boron, followed by nitrates and, later, pesticide residues.  Ultimately, there were very high levels of selenium in the water of the Kesterson Reservoir.  Although selenium is a trace element and is necessary for the basic functioning of organisms, it can be extremely toxic at higher concentrations.  The U.S. EPA has set levels for maximum selenium in water at 10 parts per billion (p.p.b) and in soil, 4 p.p.b.  Kesterson had selenium levels as high as 3,000 p.p.b. in water and 250 p.p.b in soil (Maugh II)!


The bioaccumulation of selenium in the water concentrated in the algae, roots of plants, plankton, aquatic insects, and mosquito fish.  When the aquatic birds would eat the selenium in concentrated substances, they would naturally have higher levels of selenium through biomagnification.  347 nests from the Kesterson aquatic birds, such as eared grebes, American coots, stilts, avocets, and many duck species were followed in order to examine their eggs (Ohlendorf).  40% of the nests had one or more dead embryos and 20% had embryos and chicks with severe abnormalities, which “ranged from missing or abnormal eyes, missing, crossed or reduced beaks, micromelia and amelia in their legs and wings, clubfoot and ectrodactyly in their feet and exencephaly and hydrocephaly in their brains” (Ohlendorf).  Cattails were dying, algal blooms were occurring, fewer waterfowl were present, and all but one species of fish had been destroyed (Garone).


From the beginning, the directors of the U.S. Fish and Wildlife Service and Bureau of Reclamation that had collectively created Kesterson National Wildlife Refuge were unwilling to acknowledge the nature or magnitude of the selenium threat and dismissed the “Concern Alert” (Garone).  Citing the results of tests on birds collected at Kesterson by the CA Department of Fish and Game, in October 1984 the California Department of Health Services issued the first of many notices limiting waterfowl consumption from the area around Kesterson.  The USFWS ultimately closed Kesterson’s ponds to public access.  On February 5, 1985, the State Water Resources Control Board ordered the Department of Interior to resolve the problem at Kesterson (Garone).  It ordered the Bureau of Reclamation to submit a cleanup and abatement plan within five months, and to implement the cleanup plan within three years (Garone).

The Bureau examined five options in the final environmental impact statement: a no-action alternative, a flexible response plan, an immobilization plan, a wetland restoration/onsite disposal plan, and an offsite disposal plan (Garone).  The Bureau chose the phased approach, incorporating three of these remediation options, which would be implemented in succession if the previous option proved unsatisfactory.  On March 19, 1987, the State Water Resources Control Board (SWRCB) rejected the phased approach and ordered the Bureau to clean up Kesterson Reservoir by August 19, 1988, using the onsite disposal plan (Garone).  However, new evidence showed this would not be effective.  Instead, the SWRCB ordered the Bureau to fill all areas where it expected ephemeral pools to form and to fill all areas to six inches above the expected seasonal rise in groundwater level by January 1, 1989 (Garone).  They thought this would solve the problem forever.  However, in June of 1999, the Sacramento consulting firm CH2M Hill released to the press the results of its most recent studies of mice and voles at Kesterson: “the firm’s report revealed that up to twenty-nine of eighty-seven house mice, deer mice, western harvest mice, and voles collected during 1998 were hermaphroditic” (Garone).  Because 1998 was a particularly wet year, water pooled for months at Kesterson, possibly remobilizing the selenium, returning it to the food chain, and causing these new cases of development of malformed organisms or growths.  The aftermath of poor planning are lingering for much longer than anticipated.



This post was written by Carolin Meier & Daria Sarraf.

Works Cited

Garone, Philip. “The Tragedy at Kesterson Reservoir: A Case Study in Environmental History and a Lesson in Ecological Complexity.” Environs: Environmental Law and Policy Journal 22.2 (1999): 107-44. Print.

Maugh II, Thomas H. “Microbes Clean Soil Polluted With Selenium.” Los Angeles Times. N.p., n.d. Web. 10 Apr. 2013. <>.

Ohlendorf, Harry M. “The Birds of Kesterson Reservoir: A Historical Perspective.” Aquatic toxicology (Amsterdam, Netherlands) 57.1-2 (2002): 1-10. Print.

Taylor, Ronald B. “Wetland Considered Proving Ground for Toxics Cleanup Plan.” Los Angeles. N.p., 17 Jan. 1987. Web. 11 Apr. 2013. <>.

U.S. Fish and Wildlife Service, Bruce Waddell. Selenium can cause deformities in birds. The ducks on the left were exposed to high concentrations of selenium in the Middle Green River Basin in Utah. Great Lakes Echo. N.p., 12 Dec. 1990. Web. 11 Apr. 2013.

Vencil, Betsy. “The Migratory Bird Treaty Act – Protecting Wildlife on our National Refuges – California’s Kesterson Reservoir, a Case in Point.” Natural Resources Journal 26.3 (1986): 609. Print.

Zahm, Gary. “Stop: Kesterson NWR.” Invisible 5. N.p., n.d. Web. 11 Apr. 2013.



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