The National Rivers and Streams Assessment (NRSA) is a statistical survey of the condition of our nation's perennial rivers and streams. It is designed to provide information on the extent of flowing waters that support healthy biological condition and recreation, estimate how widespread major stressors are that impact the nation’s rivers and streams water quality, and provide insight into whether rivers and streams nationwide are getting cleaner.

This dataset is an archived (zipped) file comprised of chemical, physical and biological files used in developing the NRSA (2008/2009) report. Sampling was conducted over two summers (2008/2009) at approximately 2000 sites in the conterminous U.S. Sites were selected using a statistical survey (probabilistic) design. The files include water chemistry, benthic macroinvertebrates, fish assemblage, physical habitat, landscape metrics, enterococci, etc. Users are encouraged to visit the NARS data webpage for updates to data files and data from other surveys. https://www.epa.gov/national-aquatic-resource-surveys/data-national-aquatic-resource-surveys.

Citation for the NRSA 2008/2009 archived data: U.S. Environmental Protection Agency. National Aquatic Resource Surveys. National Rivers and Streams Report. Archived Data. (INSERT data and metadata files used). Available from U.S. EPA web page: https://www.epa.gov/national-aquatic-resource-surveys/national-rivers-and-streams-assessment-2008-2009-results.

EPA encourages users who are publishing subsets of the data (say as part of a journal article publication) to include the above citation. EPA also encourages users of the data to include the following acknowledgement: “The National Rivers and Streams Assessment 2008/2009 data were a result of the collective efforts of dedicated field crews, laboratory staff, data management and quality control staff, analysts and many others from EPA, states, tribes, federal agencies, universities, and other organizations. Please contact nars-hq@epa.gov with any questions.”. Citation information for this dataset can be found in Data.gov's References section.