Summary

Description

Buffalo Lake National Wildlife Refuge is located in the Southern High Plains in Randall County, Texas. The lake from which the Refuge received its name has not contained water since the 1980s. In 1987, a Phase I contaminants investigation of the Refuge was conducted by the U.S. Fish and Wildlife Service, Arlington, Texas, Field Office. The results of this investigation indicated that elevated concentrations of nutrients nitrogen and phosphorus compounds, salts, copper, strontium, and zinc were found in and downstream of cattle feedlot waste retention lagoons; Tierra Blanca Creek, the major lotic contributor of the Refuge, had degraded water quality, primarily attributed to runoff and discharges from cattle feedlots; and that nutrient concentrations retained in soils in the dry reservoir bed in Buffalo Lake National Wildlife Refuge were elevated to the extent that inundation could create unacceptably high nutrient concentrations in the surface water. Consequentially, in 1993, a Phase II contaminants study was initiated at the Refuge by the U.S. Fish and Wildlife Service to evaluate the extent of contamination in stormwater runoff entering the Refuge via Tierra Blanca Creek; to determine the extent of contamination in soils and vegetation within the Refuge; to evaluate the ability of crops grown in the Refuge to reduce soil contaminant concentrations; and to monitor contaminant levels in soils, surface water, and vegetation of moist soil management units constructed in the southern portion of the Refuge. To accomplish these objectives, surface water samples, representing a stormwater surge, were collected in Tierra Blanca Creek, upstream of the Refuge, analyzed for nutrient and total metal content, and compared with water data from the Phase I study and criteria values protective of aquatic life. Surface water, groundwater, soil, and biological samples were collected within the boundaries of the Refuge and analyzed for total metal and nutrient content. Data from these water analyses were compared with criteria and other screening values protective of aquatic life, while data obtained from the soils component of this study were compared with U.S. median background levels. The soil data were also statistically compared with data from the Phase I study to determine if contaminant levels had increased or decreased within the Refuge between 1987 and 1993. Biological samples consisting of vegetation and terrestrial invertebrates were analyzed for total metals. The resulting data from this portion of the study were statistically analyzed and compared with criteria protective of wildlife to determine the bioavailability of contaminants within the Refuge. In 1994, sediment and additional surface water, groundwater, soil, and biological samples were collected from the Refuge. The water samples were analyzed for dissolved metal and nutrient content. Soil and sediment samples were analyzed for total metal and nutrient content. Biological samples consisted of vegetation, aquatic macroinvertebrates, aquatic vertebrates, and avian specimens which were analyzed for total metals. In addition, sediment, soil, and biological samples were analyzed for total polychlorinated biphenyls and organochlorine pesticide residues. Water, soils, sediment, and biological data resulting from these analyses were compared with criteria and screening values protective of wildlife resources to further interpret contaminant levels within the Refuge.