Prognosis on Managing Trace Elements

Abstract

Concern over the potentially toxic effects of trace elements in agricultural drainage waters has been aroused by the discovery of selenium poisoning of wildlife at Kesterson Reservoir, California, and was heightened further through discovery of elevated levels of selenium in shallow ground water underlying extensive areas of San Joaquin Valley's west side. Recent investigations by the U.S. Department of the Interior's National Irrigation Water Quality Program (NIWQP) revealed that similar trace‐element problems exist in several other western states including Nevada, Utah, Wyoming, and Colorado, as well as the Tulare Lake Bed and Salton Sea in California. Management options assessed for trace elements discharged from irrigated lands include source control, drain‐water reuse, drain‐water treatment, and removal of contaminants, disposal, and institutional and jurisdictional control measures. A combination of source control and other drainage‐water‐management options has the potential to reduce the toxic‐element problem. An initial prognosis indicates that a status quo scenario will be unacceptable to the public. Agriculture will be increasingly challenged in its use of water and land resources and the perceived impacts on the quality of the environment. The effect of drainage reduction and other management options on reducing the discharge of trace elements is, to some extent, influenced by site‐specific conditions. The economic viability of agriculture will be severely tested in the most severely trace‐element‐impacted lands, water, and biota, and this may lead to changes in land use.