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An objective of the U.S. Geological Survey's National Water-Quality Assessment Program is to describe relations between the physical and chemical characteristics of streams, associated biological communities, and surrounding landscapes. The analyses of these relations are part of an integrated approach for explaining trends and describing current water-quality conditions. Fish assemblages and environmental characteristics (physical and chemical) were evaluated at 21 streams during 1999 in the Eastern Highland Rim region of the lower Tennessee River Basin. Study reaches (average length 656 feet) were selected to represent stream conditions for basins of 30 to 100 square miles and varying degrees of land-use intensity. Major emphasis was placed on identifying sampling reaches in agricultural landscapes due to the dominance of agriculture land use in the Eastern Highland Rim.
Fish communities were sampled using a combination of seining and electrofishing. Instream and terrestrial (physical) characteristics were measured at 11 equidistant transects within each study reach. At each of the 11 transects, water depth, dominant substrate, and velocity were measured at 3 points across the channel. Additional measurements, such as bank angle, canopy angle, percent canopy closure, and stream gradient, were made along the bank and mid-channel areas. Chemical characterization was based on two samples collected at each site; one during spring and the other during late summer. Water-quality measurements included basic field properties, nutrient and organic carbon concentrations, and bacterial counts.
The effect of physical, chemical, and biological characteristics will be evaluated using multiple analysis techniques, such as multivariate statistics, similarity indices, and multimetric analyses. This information will contribute to a better understanding of how land use affects water quality.
U.S. Department of the Interior, U.S. Geological Survey
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