|
AQUATIC ECOLOGY IN THE YELLOWSTONE RIVER BASIN NAWQA PROGRAM David A. PetersonU.S. Geological Survey Cheyenne, Wyoming The Yellowstone River Basin is one of more than 50 river basins nationwide selected for study by the U.S. Geological Survey (USGS) under the National Water Quality Assessment (NAWQA) program. The overall goals of the NAWQA program are to (1) describe current water-quality conditions for a large part of the of the Nation's freshwater streams and aquifers, (2) describe how water quality is changing over time, and (3) improve our understanding of the primary natural and human factors affecting water quality. An ecological investigation is underway throughout the 70,100 square mile basin in Wyoming, Montana, and North Dakota. Sampling sites have been selected on the basis of an environmental stratification including factors such as ecoregion, geology, and land use. During 1998, 24 sites were visited to collect samples of fish tissue and bed sediment. Samples collected in cooperation with fisheries biologists from Yellowstone National Park indicated the presence of DDT and two metabolites, DDD and DDE, at a total concentration of 64.5 ug/kg, in cutthroat trout from the Yellowstone River at Fishing Bridge. A relatively low concentration of DDE was detected in a sample of cutthroat trout collected from Soda Butte Creek just inside the Park boundary. Organochlorine insecticides were not detected in the bed sediment from either site in the Park. Fish-tissue samples also indicated the presence of DDT or metabolites of DDT in the Yellowstone River at Corwin Springs and in the West Fork of Mill Creek. The total concentration of DDT and DDE in brown trout from the Yellowstone River at Corwin Springs was about 2 orders of magnitude less in the 1998 samples than in samples collected during the 1950's. The NAWQA investigation also contains an ongoing intensive ecological assessment of 10 sites, which include the Yellowstone River at Corwin Springs and Soda Butte Creek near the Park boundary. The intensive ecological assessment is comprised of fish-community measures, quantitative and qualitative samples of algae and invertebrates, and habitat measurements, in addition to the fish-tissue and bed-sediment samples described previously. |
|
U.S. Department of
the Interior, U.S. Geological Survey |