Date of this Version
Frenzel, S.A, R.B. Swanson, T.L. Huntzinger, J.K. Stamer, P.J. Emmons, and R.B. Zelt, 1998. Water quality in the central Nebraska basins, Nebraska, 1992-95. U.S. GEOLOGICAL SURVEY CIRCULAR 1163. 38pp.
This report is intended to summarize major findings that emerged between 1992 and 1995 from the water-quality assessment of the Central Nebraska Basins Study Unit and to relate these findings to water-quality issues of regional and national concern. The information is primarily intended for those who are involved in waterresource management. Indeed, this report addresses many of the concerns raised by regulators, water-utility managers, industry representatives, and other scientists, engineers, public officials, and members of stakeholder groups who provided advice and input to the USGS during this NAWQA Study-Unit investigation. Yet, the information contained here may also interest those who simply wish to know more about the quality of water in the rivers and aquifers in the area where they live.
Land use in central Nebraska appears to affect water quality significantly; streams in rangelands generally had fewer occurrences and smaller concentrations of pesticides than did streams in croplands where corn and soybeans were planted extensively. Subbasins with greater proportions of rangeland, such as the Dismal River, had negligible herbicide concentrations. The largest pesticide concentrations were in storm runoff following pesticide applications. Because some pesticide concentrations may exceed the U.S. Environmental Protection Agency’s (USEPA) drinking-water Maximum Contaminant Levels (MCLs) in storm runoff, the timing and intensity of rainfall has implications for drinking-water supplies. Pesticides in streams from storm runoff may enter alluvial aquifers as a consequence of ground-water withdrawals. Sites with degraded water chemistry commonly had degraded physical habitats as well. Streamflow regulation of the Platte River has affected water quality through habitat alterations that are deleterious to native species. The combination of degraded physical and chemical environments commonly resulted in structurally simple fish communities.
National Water-Quality Assessment Program .. 1
Summary of major issues and findings... 2
Environmental setting and hydrologic conditions.... 4
Major issues and findings ... 6
Nitrate content in water is related to agricultural land management 6
Agricultural activities potentially affect the management of public water supplies . 8
Water quality in the Platte River alluvial aquifer may be affected by surface-water quality in areas of ground-water withdrawals .. 10
Aquatic environments potentially are altered by human activities... 12
Aquatic and migratory species are affected directly by changes in the physical characteristics of the Platte River .. 14
Water-quality conditions in anational context ... 16
Study design and data collection .. 20
Summary of compound detections and concentrations ... 22
References . 28