Reconnaissance investigation of water quality, bottom sediment, and biota associated with irrigation drainage in the middle Arkansas River basin, Colorado and Kansas, 1988-89

During the last several years, concern by the U.S. Department of the Interior has been increasing about the potential effects of irrigation drainage on the health of humans, fish, and wildlife. During 1988, a reconnaissance investigation was made of irrigation-drainage quality in the middle Arkansas River basin in southeastern Colorado and southwestern Kansas. This area was selected because high concentrations of selenium previously had been detected at several sites on the Arkansas River and its tributaries. This investigation was part of a program initiated in 1985 by the U.S. Department of the Interior to evaluate the effects of irrigation drainage on water quality, bottom sediment, and biota in the Western United States. Water, bottom-sediment, and biota samples were collected at 14 surfacewater sites--? sites on the Arkansas River, 2 sites on tributary streams, and 5 sites on reservoirs. Ground-water samples were collected from five municipal wells completed in the Arkansas River valley alluvial aquifer. Drainage from irrigated land underlain by marine shale affects the Arkansas River between La Junta, Colo. , and Deerfield, Kans. ; two tributary streams in the vicinity of Pueblo, Colo. ; and several off-channel reservoirs. Selenium was the only trace constituent associated with irrigation drainage that was detected at elevated concentrations in water, bottom sediment, and biota. Selenium concentrations in surface water ranged from 1 microgram per liter, in Pueblo Reservoir near the upstream end of the study area in Colorado, to 52 micrograms per liter in the St. Charles River near Vineland, Colo. The maximum concentration detected in alluvial ground water was 29 micrograms per liter at Las Animas, Colo. State drinking-water standards and the U.S. Environmental Protection Agency maximum contaminant level for selenium (10 micrograms per liter) were exceeded at three streams sites and three ground-water sites. State aquatic-life standards and the U.S. Environmental Protection Agency criterion for acute exposure to selenium were not exceeded at any sites on the Arkansas River or in any reservoirs. However, the Colorado standard for chronic exposure and the U.S. Environmental Protection Agency criterion for chronic and acute exposure were exceeded in two tributary streams The U.S. Environmental Protection Agency criterion for chronic exposure was exceeded at four sites on the Arkansas River and in three reservoirs. Elevated concentrations of selenium in bottom of five reservoir sites and at one tributary was 5.4 micrograms per gram in Lake Meredith site near Geometric mean selenium concentrations in collected at reservoirs during the spring were 42 micrograms per gram dry weight), intermediate grams per gram), and lowest in American coots The maximum selenium concentration (56 micrograms the liver of a black-necked stilt from Lake Meredith sediment occurred at four The maximum concentration Ordway, Colo. livers from bird species highest in killdeer (9.9 to in mallards (9.7 to 24 micro(12 to 15 micrograms per gram), per gram) was detected in in Colorado. Five species of fish from the Arkansas River had selenium concentrations ranging from 2.1 to 18.5 micrograms per gram dry weight, and three species from the tributaries had selenium concentrations ranging from 3.6 to 16.9 micrograms per gram. Thirteen species of fish in the reservoirs had selenium concentrations ranging from 2.2 to 20 micrograms per gram. Selenium concentrations in invertebrates from the Arkansas River, tributaries, and reservoirs ranged from 2.7 to 8.7 micrograms per gram. Tie maximum concentration of selenium detected in plants was 14 micrograms oer gram in a sample of algae from Lake Meredith in Colorado. Eight organoctilorine pesticides were detected in some samples of bird livers and eggs and in, fish from the reservoirs, but all concentrations were within the ranges of reported background concentrations. No evidence of deformity or reproductive failure was observed for any bird or fish species; however, the study was not designed to assess reproduction or to determine the extent of embryonic deformities. Selenium concentrations in some samples of food organisms (small fish, invertebrates, and aquatic plants) exceeded the dietary concentration of 10 micrograms per gram wet weight demonstrated to alter reproduction in mallards. Nearly all fish samples had selenium concentrations exceeding the 85th percentile established by a national survey. Nearly all fish samples from three reservoirs and almost none from two'other reservoirs had whole-fish concentrations of selenium exceeding the concentration that correlated with reproductive impairment in bluegills. Selenium concentrations in fish collected positively correlated to selenium concentrations other relations between abiotic and biotic mat from reservoir sites were in the reservoir water. No ices were identified. Elevated concentrations of aluminum, arsenic, copper, lead, mercury, and zinc also were determined in at least one matrix (water, sediment, or biota) at one or more sites. The source of lead, mercury, and zinc may be mine drainage upstream from the study area.