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

Home Browse Search

Elevated concentrations of selenium in bottom sediment occurred at four of five reservoir sites and at one tributary site. The maximum concentration was 5.4 micrograms per gram in Lake Meredith near Ordway, Colo. Geometric mean selenium concentrations in livers from bird species collected at reservoirs during the spring were highest in killdeer (9.9 to 42 micrograms per gram dry weight), intermediate in mallards (9.7 to 24 micro- grams per gram), and lowest in American coots (12 to 15 micrograms per gram). The maximum selenium concentration (56 micrograms per gram) was detected in the liver of a black - necked stilt from Lake Meredith 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 micro- grams per gram. Thirteen species of fish in the reservoirs had selenium concentrations ranging from 2.2 to 20 micrograms per gram. Selenium concentra- tions in invertebrates from the Arkansas River, tributaries, and reservoirs ranged from 2.7 to 8.7 micrograms per gram. The maximum concentration of selenium detected in plants was 14 micrograms per gram in a sample of algae from Lake Meredith in Colorado. Eight organochlorine 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 concentra- tions. No evidence of deformity or reproductive failure was observed for any bird or fish species; however, the study was not designed to assess reproduc- tion 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 from reservoir sites were positively correlated to selenium concentrations in the reservoir water. No other relations between abiotic and biotic matrices 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. 2