ABSTRACT
This chapter summarizes a number of National Water Quality Assessment (NAWQA) reports containing historical and current case studies on fish and associated stream habitats in the upper Snake River Basin (USNK). The US Geological Survey (USGS) NAWQA Program was initiated to define the status and trends in the quality of the nation’s surface- and ground-water resources. One important aspect of this program addresses the relations of physical and chemical characteristics of streams and associated fish assemblages. The chapter describes fish assemblages and their spatial patterns within the USNK, and identifies and characterizes some of the predominant environmental variables that affect fish assemblages. It also identifies attributes, or metrics, of fish assemblages, which will be useful in evaluating biotic integrity. The chapter discusses future data needs related to using fish assemblages to assess conditions of western streams. It also provides a framework for using fish assemblages to develop an Index of Biotic Integrity for streams in the USNK.
