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Interactive Map Provides a Long-Term Look at Changes in River and Stream Quality

Screen shot of the USGS interactive trend mapper_
The new USGS interactive map provides a long-term look at changes in the quality of our rivers and streams, using data from 74 organizations. Image Credit: USGS.

A new U.S. Geological Survey (USGS) interactive map provides a comprehensive, long-term assessment of changes in the chemical composition and quality of our rivers and streams over the last four decades.

Since passage of the Clean Water Act in 1972, Federal, State, and local governments have invested billions of dollars to reduce the amount of contaminants entering rivers and streams. To understand the return on these investments and to effectively manage and protect the Nation's water resources, it's essential to know how water quality has changed over time. A new, interactive mapping tool, developed by the USGS National Water-Quality Assessment Project, allows users to do just that—visualize long-term changes in water quality and in health of aquatic life at hundreds of sites on streams and rivers across the United States.

Users of the on-line mapping tool can explore trends in more than 50 water-quality constituents (such as nutrients, salinity, and pesticides) and 38 aquatic-life metrics (such as numbers of fish, macroinvertebrates, and algae) for four periods: 1972–2012, 1982–2012, 1992–2012, and 2002–2012. The data that underlie the trends were compiled for almost 1,400 sites in more than 50 major river basins collected by Federal, State, Tribal, regional, and local governmental agencies and nongovernmental organizations.

A companion report documents the procedures used to compile and process the data and the methods used to determine the trends. It also provides a brief summary of the trend results along with examples of how to interpret them. Collectively, the trend results provide insight into how natural variation, human activities, and management decisions have contributed to water-quality changes over time in the Nation's rivers and streams.

The USGS National Water-Quality Assessment Project provided the funds for the study.

Reference

Oelsner, G.P., Sprague, L.A., Murphy, J.C., Zuellig, R.E., Johnson, H.M., Ryberg, K.R., Falcone, J.A., Stets, E.G., Vecchia, A.V., Riskin, M.L., De Cicco, L.A., Mills, T.J., and Farmer, W.H., 2017, Water-Quality Trends in the Nation's Rivers and Streams 1972-2012—Data Preparation, Statistical Methods, and Trend Results: U.S. Geological Survey Scientific Investigations Report 2017-5006, 136 p., doi:10.3133/sir20175006.

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