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In 1988, reports for seven of the reconnaissance investigations were <br />published. Reports for the remaining two areas were published in 1990. Based <br />on results of the first nine reconnaissance investigations, four detailed <br />studies were initiated in 1988: Salton Sea area, Stillwater Wildlife <br />Management area, middle Green River basin area, and Kendrick Reclamation <br />Project area. Eleven more reconnaissance investigations were initiated in <br />1988: <br />California: Sacramento Refuge Complex <br />California - Oregon: Klamath Basin Refuge Complex <br />Colorado: Gunnison and Uncompahgre River basins and <br />Swe_itzer Lake <br />Pine River Project <br />Colorado- Kansas: Middle Arkansas River basin <br />Idaho: American Falls Reservoir <br />New Mexico: Middle Rio Grande Project and Bosque del Apache <br />National Wildlife Refuge <br />Oregon: Malheur National Wildlife Refuge <br />South Dakota: Angostura Reclamation Unit <br />Belle Fourche Reclamation Project <br />Wyoming: Riverton Reclamation Project <br />All studies were conducted by interbureau field teams composed of a <br />scientist from the U.S. Geological Survey as team leader, with additional <br />U.S. Geological Survey, U.S. Fish and Wildlife Service, and U.S. Bureau of <br />Reclamation scientists representing several different disciplines. The <br />reconnaissance investigations were directed toward determining whether <br />irrigation drainage: (1) has caused or has the potential to cause significant <br />harmful effects on human health, fish, and wildlife, or (2) may adversely <br />affect the suitability of water for other beneficial uses. <br />The middle Arkansas River basin was selected for study primarily because <br />historical records indicated the occurrence of high concentrations of selenium <br />in surface water in the basin. Selenium is a primary element of concern in <br />drainage from irrigated land. The median selenium concentration from 1975 <br />through 1987 in the Arkansas River near Coolidge, Kans., was 19 pg /L, the <br />highest of any site in the U.S. Geological Survey National Stream Quality <br />Accounting Network (NASQAN). Concentrations of selenium greater than the <br />State drinking water standard (10 pg /L) have been detected at several other <br />sites on the Arkansas River and its tributaries in the study area. The <br />Fryingpan- Arkansas project, constructed and operated by the U.S. Bureau of <br />Reclamation, provides a supplemental water supply to irrigators in the study <br />area. Although there are no U.S. Fish and Wildlife Service refuges in the <br />study area, it is used intensively by migratory waterbirds, and several State - <br />operated wildlife areas are located in the study area. <br />4 <br />