National Water-Quality Assessment (NAWQA) Program

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Water-Quality Trends in Streams and Rivers

Study Design

Determine trends in water chemistry (nutrients, pesticides, sediment, carbon, and salinity) and aquatic ecology (fish, macroinvertebrates, and algae) for four time periods: 1972-2012, 1982- 2012, 1992-2012, and 2002-2012. Trends in concentration and load will be evaluated for water chemistry.

Evaluate the geographic distribution of improving and deteriorating water-quality conditions nationwide.

Determine the potential impact of these changes on the health of humans and aquatic life.

Identify the major causes of these changes.

One of the major goals of the NAWQA Project is to determine how water-quality conditions change over time. To support that goal, long-term consistent and comparable monitoring has been conducted on streams and rivers throughout the Nation. Outside of the NAWQA Program, the USGS and other Federal, State, and local agencies also have collected long-term water-quality data to support their own assessments of changing water-quality conditions. For the first time, these data have been assembled into one database to support the most comprehensive assessment conducted to date of water-quality trends in the United States. Collectively, these data will provide insight into how natural features and human activities have contributed to water-quality changes over time in Nation's streams and rivers.

Press releases, technical announcements, and congressional briefings

Nation’s River Quality Data Could Power Deeper Science Insights (January 2017)
      Technical Announcement | Article

U.S. Rivers Show Few Signs of Improvement from Historic Nitrate Increases (October 2015)
      Press Release | Article

Trends in Nutrients and Pesticides in the Nation's Streams and Rivers (April 2014)
      Congressional Briefing

Water-quality data

Sprague, L.A., Oelsner, G.P., and Argue, D.M., 2017, Challenges with secondary use of multi-source water-quality data in the United States: Water Research, vol. 110, p. 252-261.

Geospatial data

Falcone, J.A., and LaMotte, A.E., 2016, National 1-kilometer rasters of selected Census of Agriculture statistics allocated to land use for the time period 1950 to 2012: U.S. Geological Survey data release,

Falcone, J.A., 2016, County fresh-water withdrawal water use allocated to relevant land uses in the United States: 1985 to 2010: U.S. Geological Survey data release,

Falcone, J.A., 2016, U.S. national categorical mapping of building heights by block group from Shuttle Radar Topography Mission data: U.S. Geological Survey data release,

Falcone, J.A., 2016, U.S. block-level population density rasters for 1990, 2000, and 2010: U.S. Geological Survey data release,

Falcone, J.A., 2015, U.S. conterminous wall-to-wall anthropogenic land use trends (NWALT), 1974-2012: U.S. Geological Survey Data Series 948, 33 p. DOI: 10.3133/ds948
      Available Online

List of all NAWQA trend publications


Lori Sprague, Surface-Water Trend Studies Coordinator
(303) 236-6921

James Falcone, GIS specialist
(703) 648-5008

Hank Johnson, Hydrologist
(503) 251-3472

Jenny Murphy, Hydrologist
(615) 837-4752

Gretchen Oelsner, Hydrologist
(505) 830-7982

Melissa Riskin, Hydrologist
(609) 771-3924

Karen Ryberg, Statistician
(701) 250-7422

Ted Stets, Ecologist
(303) 541-3048

Bob Zuellig, Ecologist
(970) 226-9419

The Nation's rivers and streams are a valuable resource, providing drinking water for a growing population, irrigation for crops, habitat for aquatic life, and many recreational opportunities. But pollution from urban and agricultural areas continues to pose a threat to water quality. Since passage of the Clean Water Act in 1972, Federal, State, and local governments have invested billions of dollars to reduce pollution entering streams and rivers. Yet recently, the U.S. Environmental Protection Agency reported that more than half of the Nation's stream miles have ecosystems in poor condition. In order to understand the return on these investments, and to more effectively manage and protect the Nation's water resources in the future, we need to know how and why water quality has been changing over time.

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Page Last Modified: Wednesday, 11-Jan-2017 07:52:08 EST