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National Water-Quality Assessment Project (NAWQA)

The NAWQA Project is the largest component of the NWQP as a primary source of objective and nationally consistent water-quality data and information on the quality of the Nation’s streams and groundwater.

The National Water Quality Program (NWQP) of the Water Mission Area conducts water-quality monitoring, assessment, and research activities that:

  1. Assess the current quality of the Nation’s freshwater resources and how it is changing over time,

  2. Explain how human activities and natural factors (e.g., land use, water use and climate
    variability) are affecting the quality of surface water and groundwater resources,

  3. Determine the relative effects of important sources of impairment to water resources including contaminants, excess nutrients and sediment, and altered streamflow on aquatic ecosystems, and

  4. Predict the effects of human activities, climate change, and management strategies on future water-quality and ecosystem conditions.


In 1991, Congress established NAWQA within the USGS to address a fundamental question: “What is the status of the Nation’s water quality and is it getting better or worse?” Since then, the NAWQA Project has been a primary source of objective and nationally consistent water-quality data and information on the quality of the Nation’s streams and groundwater. NAWQA Project data and models provide answers to where, when, and why the Nation’s water quality is degraded, and what can be done to improve and protect it for human and ecosystem needs.

Several highlights of recent (fiscal year 2019) accomplishments and planned (fiscal year 2020) activities are listed below:

  • Collected 1,880 water-quality samples at 110 river and stream sites through the USGS National Water Quality Network (NWQN).  Samples were analyzed for concentrations of physical properties, major ions, nutrients, pesticides, and sediment; data were published on the National Water Information System: Web Interface (NWISWeb).  Additional, value-added, analyses of water-quality conditions were performed for NWQN data collected in FY18 the computation of  water-quality loads from coastal rivers, large inland rivers, and small stream sites representative of urban, agricultural, or reference conditions. FY18 data and information were posted on the USGS ScienceBase platform.

  • Released six journal articles documenting national trends in water-quality constituents in streams and rivers. Constituents included chloride, phosphorus, and atrazine. 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.

  • Model documentation was published for water-quality models based on the SPAtially Referenced Regressions On Watershed attributes (SPARROW) modeling framework. These models were developed for 5 large regions of the Country that cover the conterminous US. For each region, models were developed for 4 different constituents including stream discharge, total nitrogen, total phosphorus and suspended sediment, amounting to 20 models in all.

  • Released four journal articles documenting results from the Regional Stream Quality Assessment (RSQA). This assessment examined the effects of chemical and physical stressors on the condition of fish, macroinvertebrate, and algal communities in small streams in five U.S. regions: Midwest, Southeast, Pacific Northwest, Northeast, and Central Coastal California. Insights gained from these studies will help resource managers choose more effective stream protection and restoration strategies based on which human and natural factors are most critical to stream quality and health.   

  • Collected groundwater-quality samples at 283 groundwater wells in 8 well networks and analyzed samples for concentrations of physical properties, major ions, nutrients, trace elements, radionuclides, pharmaceuticals, hormones, microbiological indicators, and age-dating tracers. Results are compared to human-health benchmarks to evaluate the status of groundwater quality and are also compared to previous sampling in these same wells and networks to evaluate changes in groundwater quality and the factors that affect those changes.

  • Released four journal articles that describe the status and trends of water quality in the Nation’s groundwater. Topics addressed included the lead solubility potential of untreated groundwater and hormones and pharmaceuticals in untreated groundwater.

  • Planned (FY 2020) NAWQA activities include: release of USGS Circular 1461, “Flow Modification in the Nation's Streams and Rivers”; release of fact sheets that summarize water-quality assessments of four principal aquifers; journal articles that analyze specific aspects of national groundwater quality, national trends in water-quality constituents in surface water, and relations between surface-water quality and ecological integrity of small streams across the U.S.