Draft National Rivers and Streams Assessment 2008-2009 Report

This National Rivers and Streams Assessment 2008–2009: A Collaborative Survey (NRSA) presents the results of an unprecedented sampling effort undertaken by the U.S. Environmental Protection Agency and its state and tribal partners. It provides information on the ecological condition of the nation's rivers and streams and the key stressors that affect them, both on a national and an ecoregional scale. It also discusses change in water quality conditions in streams sampled for an earlier study, the Wadeable Streams Assessment of 2004. During the summers of 2008 and 2009, more than 85 field crews sampled 1,924 river and stream sites across the country. Using standardized field methods, they sampled waters as large as the Mississippi River and as small as mountain headwater streams. Sites were selected using a random sampling technique that uses a probability-based design. This design ensures that the results of the survey reflect the full variety of river and stream types and sizes across the U.S. To determine water quality conditions, sampling results were compared to conditions at least-disturbed (or reference) sites in different ecological regions. The goals of the NRSA are to determine the extent to which rivers and streams support a healthy biological condition and the extent of major stressors that affect them. In addition, the survey supports a longer-term goal: to determine whether our rivers and streams are getting cleaner and how we might best invest in protecting and restoring them.