A new U.S. Geological Survey interactive map provides a comprehensive, long-term look at changes in the quality of U.S. rivers and streams over the last four decades. For the first time, monitoring data collected by 74 organizations at almost 1400 sites have been combined to provide a nationwide look at changes in the quality of our rivers and streams in the 40 years since passage of the Clean Water Act.

This First-of-its-kind visualization puts 40 years of national water quality data at users’ fingertips.

Tracking changes in the quality of these waterways over multiple decades is crucial for evaluating the effectiveness of pollution control efforts and protecting the nation’s water resources into the future.

The interactive map can be used to track trends of 51 water-quality constituents and 38 aquatic-life metrics at nearly 1400 sites. Track if water quality or aquatic life metrics have increased, decreased, or remained the same during four time periods:

  • 1972-2012,
  • 1982-2012,
  • 1992-2012, and
  • 2002-2012.

This map was developed by the USGS National Water-Quality Assessment Project, which conducts regional and national assessments of the Nation’s water quality to provide an understanding of current water-quality conditions, whether conditions are getting better or worse over time, and how natural processes and human activities affect those conditions.