National Water-Quality Assessment (NAWQA) Project
Assess the status and trends of aquatic ecological conditions (invertebrates, fish, algae and habitat) in rivers and wadeable streams.
Relate ecological conditions to chemical stressors (such as nutrients and pesticides), physical disturbances (such as habitat and hydrologic alterations) in the context of different environmental settings and land uses.
Enhance understanding of factors that influence the biological integrity of streams and how these stream ecosystems may respond to diverse natural and human factors.
Develop key ecological indicators of aquatic health.
Michael R. Meador1 and Robert M. Goldstein2
1U.S. Geological Survey, 12201 Sunrise
Valley Drive, MS 413, Reston, Virginia, 20192
2U.S. Geological Survey, 2280 Woodale Drive, Mounds View, Minnesota 55112
ABSTRACT.Data collected from 172 sites in 20 major river basins between 1993 and 1995 as part of the U.S. Geological Surveys National Water-Quality Assessment Program were analyzed to assess relations among basinwide land use (agriculture, forest, urban, range), water physicochemistry, riparian condition, and fish community structure. A multimetric approach was used to develop regionally referenced indices of fish community and riparian condition. Across large geographic areas, decreased riparian condition was associated with water-quality constituents indicative of non-point source inputstotal nitrogen and suspended sediment, and basinwide urban land use. Decreased fish community condition was associated with increases in total dissolved solids and range land use and decreases in riparian condition and agricultural land use. Fish community condition was relatively high even in areas where agricultural land use was relatively high (> 50% of the basin). Although agricultural land use can have deleterious effects on fish communities, the results of this study suggest that other factors also may be important, including practices that regulate the delivery of nutrients, suspended sediments, and total dissolved solids into streams. Across large geographic scales, measures of water physicochemistry may be better indicators of fish community condition than basinwide land use. Whereas numerous studies have indicated that riparian restorations are successful in specific cases, this analysis suggests the universal importance of riparian zones to the maintenance and restoration of diverse fish communities in streams.