Reconnaissance Investigation of Water Quality, Sediment, and Biota Associated with Irrigation and Drainage

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r 0169 INTRODUCTION During the last several years, there has been increasing concern about the quality of irrigation drainage and its potentially harmful effects on human health, fish, and wildlife. Concentrations of selenium greater than the water - quality criterion (35 pg /L) for the protection of aquatic life (U.S. Environmental Protection Agency, 1986) have been detected in subsurface drainage from irrigated land in the western part of the San Joaquin Valley in California. In 1983, incidences of mortality, birth defects, and reproductive failures in waterfowl were discovered by the U.S. Fish and Wildlife Service at the Kesterson National Wildlife Refuge in the western San Joaquin Valley, where irrigation drainage was impounded. In addition, potentially toxic trace elements and pesticide residues have been detected in other areas in Western States that receive irrigation drainage. Because of concerns expressed by the U.S. Congress, the U.S. Department of the Interior (DOI) started a program in late 1985 to identify the nature and extent of irrigation- induced water - quality problems that might exist in Western States. In October 1985, an interbureau group known as the "Task Group on Irrigation Drainage" was formed within the DOI. The Task Group subsequently prepared a comprehensive plan for reviewing irrigation- drainage concerns for which the DOI may have responsibility. The DOI developed a management strategy, and the Task Group prepared a comprehensive plan for reviewing irrigation- drainage concerns. Initially, the Task Group identified 20 locations in 13 States that warranted reconnaissance - level field investigations. These locations relate to three specific areas of DOI responsibilities: (1) Irrigation or drainage facilities constructed or managed by the DOI, (2) national wildlife refuges managed by the DOI, and (3) other migratory -bird or endangered- species management areas that receive water from DOI- funded projects. Nine of the 20 locations were selected for reconnaissance investigations during 1986 -87. The nine areas were: Arizona - California: Lower Colorado -Gila River Valley area California: Salton Sea area Tulare Lake area Montana: Sun River Reclamation Project area Milk River Reclamation Project area Nevada: Stillwater Wildlife Management area Texas: Lower Rio Grande - Laguna Atascosa National Wildlife Refuge area Utah: Middle Green River basin area Wyoming: Kendrick Reclamation Project area 3