Selenium Toxicity at Kesterson Reservoir
Selenium is an element that has similarities with sulfur. It
is widely distributed in soils, rocks, and water. In small amounts it is a
nutrient, in large amounts, a toxin. It might achieve its toxic effect through its
ability to replace sulfur in proteins. Selenium poisoning in animals results
when they drink contaminated water or ingest Se that has worked its way up the
and trace elements stay
buildup in the root zone, osmotic potential. Irrigation causes trace elements to move.
tile drains were installed to maintain the water table at about 2
meters in depth, reducing water-logging and salt accumulation in the root
- In 1971,
the 134 km long San Luis Drain was terminated at a series of
shallow regulating ponds, later known as Kesterson Reservoir,
Bureau constructed this reservoir which was later incorporated into the
national wetlands system.
Kesterson received some fresh water flows, but by 1982 inflow consisted
solely of saline water from subsurface drains, high in trace elements and
- As early as 1981, ranchers in the
vicinity noticed livestock abnormalities and death. They questioned the Bureau's operating
practices and a rancher, James Claus, filed suit and a complaint
with the SWRCB. In 1983, a large
die-off of birds and later discovered reproductive failure further alerted
Fish and Wildlife Service officials to the toxicity of the reservoir.
February 5th, 1985, after a series of evidentiary hearings, the SWRCB
ordered the Bureau to revise operating procedures within 6 months or close
Kesterson. At the federal level,
the House Subcommittee on Water and Power Resources met in Los Baņos to
investigate Kesterson's toxicity and the Bureau's involvement on March
the meeting, the California representative of the Department of the
Interior, Carol Hallet, announced that the Bureau was going to shut down
the reservoir and stop water deliveries to 42,000 acres of farmland in
the Westland Water District.
This alarmed farmers who depended on the water for irrigation and
later the Bureau decided to continue deliveries, phase out Kesterson, and
plug all the drains; a process that was completed in May of 1986.
final solution to agricultural drainage exists today and the majority of
drainage water in the San Joaquin Valley, approximately 75,000
acre-feet, is at some point discharged into the San Joaquin River
(aside from the few evaporation ponds in operation in the region).
April 2001, the Bureau of Reclamation filed with the United States
District Court in Fresno a plan of action to provide drainage to the San
Luis Unit. Under the court's order, Reclamation must act promptly to
provide drainage service to the San Luis Unit. The plan of action provides that Reclamation will evaluate
the economic feasibility and the environmental impacts/benefits of all
viable drainage alternatives to support a decision on how to provide
drainage service to the drainage-affected irrigated lands in the San Luis