Water Quality in the Central Nebraska Basins, Nebraska, 1992-1995
By R.B. Swanson
ABSTRACT:
Full implementation of the U.S. Geological Survey National Water-Quality
Assessment Program (NAWQA) was begun in 1991 to describe the quality of the
Nation's water resources using nationally consistent methods. The Central
Nebraska Basins Study Unit, one of 20 study units started that year,
consists of 30,000 square miles of the Platte River Basin from the
confluence of the North and South Platte Rivers near North Platte, Nebraska,
to the mouth near Omaha, Nebraska. The findings of the investigative
activities conducted from 1992 through 1995 have been summarized.
Land use appears to affect water quality dramatically. Streams with a
greater proportion of rangelands, such as the Dismal River, generally had
fewer occurrences and smaller concentrations of pesticides than did streams
in croplands where corn and soybeans were planted extensively. The largest
pesticide concentrations were detected in storm runoff following pesticide
applications in cropland areas. The timing and intensity of rainfall has
implications in the management of drinking-water supplies, because
pesticides in storm runoff may enter alluvial aquifers as a consequence of
groundwater withdrawals for drinking water. Sites with degraded water
chemistry, such as Shell Creek, also commonly had degraded physical
habitats. The combination of degraded physical and chemical environments
often results in structurally simple fish communities. Finally, streamflow
regulation of the Platte River and possibly climatic change have also
altered riverine habitat impacting water quality and natural species
composition.
CITATION:
Swanson, R.B., 1998, Water quality in the Central Nebraska Basins, Nebraska,
1992-1995 [abs.]: Ninth Platte River Basin Ecosystem Symposium, Kearney, Nebr.,
February 24-25, 1998, Proceedings, p. 61.