US Fish & Wildlife Service



Date of this Version



Published in Contaminant Report Number: R6/512M/93, 1-57, (1993)


This study was conducted to determine background levels of metals and organochlorine compounds in aquatic habitats in the Republican River basin, a large watershed in eastern Colorado, eastern Wyoming, southern Nebraska, and northwestern and northcentral Kansas. Reservoirs and their tributaries in the basin are concentration areas for bald eagles, migratory waterfowl, and occasionally for whooping cranes and other federally-listed threatened and endangered wildlife. The sampling was done to assess risk to federal trustee resources that use aquatic habitats in the basin.

We sampled sediments at 29 locations and fish at 30 locations on the Republican River and tributaries in eastern Colorado, southern Nebraska, and northern Kansas in 1989 and 1990 to assess concentrations of metals and long-lived organochlorine compounds in the basin.

Arsenic concentrations in sediments from the upper end of Lovewell Reservoir and from White Rock Creek below the reservoir were very high. Further investigation of the source(s) of the arsenic and its distribution may be warranted.

Copper concentrations in White Rock Creek and upper Lovewell Reservoir sediments are suspect, and copper concentrations in the upper end of Norton Reservoir are high.

Zinc concentrations in many of the sediment composites we collected were well above the mean concentrations found in U.S., western U.S., and northern Great Plains soils.

Barium concentrations in fish were higher than those in fish from other collection locations in Kansas. The concentration found in the dace and chub composite from the St. Francis Wildlife Area was especially high. However, because information about the effects of barium on fish or wildlife is very limited, we can not estimate the effects, if any, of the concentrations in fish samples we collected.

Fish composites at ten sampling locations contained high levels of chromium. However, assessment of these concentrations is difficult because there are no obvious sources of contamination associated with the collection locations.