Water Quality in the Nation’s Streams and Rivers – Current Conditions and Long-Term Trends

Featured Study: Flow Modification of the Nation's Streams

Featured Study: Flow Modification of the Nation

A new USGS study reports that human management of land and water resources have modified natural patterns of streamflow along more than 1.2 million miles of U.S. streams. Flow modification was associated with losses of native fish or invertebrates.

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Featured Study: Water-Quality Changes in U.S. Rivers

Featured Study: Water-Quality Changes in U.S. Rivers

Human activities have markedly changed the water quality of rivers in the past few decades according to a new study by the U.S. Geological Survey—concentrations of some water- quality constituents have increased while others have decreased.

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The Nation's rivers and streams are a priceless resource, but pollution from urban and agricultural areas pose a threat to our water quality. To understand the value of water quality, and to more effectively manage and protect the Nation's water resources, it's critical that we know the current status of water-quality conditions, and how and why those conditions have been changing over time.

The Nation's rivers and streams are a priceless resource—they provide drinking water for a growing population, irrigation for crops, habitat for aquatic life, and countless 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.  Knowing the current water-quality conditions of our rivers and streams and where those conditions have improved or deteriorated is critical information for resource managers and the public. 

Two of the major goals of the USGS National Water-Quality Assessment (NAWQA) Project are to determine the current status of water-quality conditions in the Nation’s streams and rivers and to determine how those conditions are changing over time. These goals are accomplished on a national scale through two projects:

(1) Objective 1: Tracking Water Quality of the Nation's Rivers and Streams—The USGS National Water Quality Network (NWQN) monitors water-quality conditions in streams and rivers throughout the Nation using consistent and comparable methods.  The Water-Quality Tracking page provides annually updated information on water-quality concentrations, loads, and trends at sites located throughout the U.S.

(2) Objective 2: Water-Quality Changes in the Nation's Streams and Rivers—Outside of the NAWQA Project, 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. To support the second objective, these data have been combined with USGS data to support the most comprehensive assessment to date of water-quality trends in the United States. Collectively, these data provide insight into how natural features and human activities have contributed to water-quality changes in the Nation's streams and rivers. Use the Water-Quality Trends mapping tool to visualize trends in water chemistry (nutrients, pesticides, sediment, carbon, and salinity) and aquatic ecology (fish, invertebrates, and algae) for four time periods: 1972-2012, 1982-2012, 1992-2012, and 2002-2012.