Author(s): Stanley C. Conway; Glen D. Sanders
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Keywords: No Keywords
Abstract: Trace elements such as arsenic, boron, and selenium are usually present in drainage return flows from irrigation of arid or semi-arid lands. Historically, concern for these elements was apparent only when their concentrations became a threat to the irrigated crops. The eruption of selenium poisoning of migratory birds that developed at Kesterson Reservoir in the mid 1980s focused the Nation’s attention on the need to avoid concentrating trace elements in the biological food chain. After a broad-based review of federal irrigation project return flows by the Secretary of the Interior, they cited only a few existing projects as possible problem areas. Nevertheless, as a steward of natural resources of the western states, the Bureau of Reclamation viewed this incident as an indication that there was a need to improve the planning process for irrigation project development. Legislative direction came in the 1986 Garrison Diversion Unit Reformulation Act, Public Law 99-294. Section 10 of this Act requires that Reclamation’'s irrigation suitability land classification activities for the development of Federal irrigation projects; “...include an investigation of soil characteristics that might result in toxic or hazardous irigation return flow": This paper describes the process that Reclamation has developed to avoid potentially harmful elevated trace element concentrations in ecological systems [2]. This process involves estimating trace element loads that may be carried in irrigation return flows and using that information to assess environmental impacts and in the formulation of project configuration and size.
Year: 1997