National Water Quality Program

National Water-Quality Assessment Project (NAWQA)

NAWQA Science, Just a Click Away

NAWQA Science, Just a Click Away

Learn about current conditions and trends in the quality of the Nation's rivers, streams, and groundwater and the health of aquatic ecosystems. Easy access to data, mappers, and publications!

NAWQA Home Page

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.


The NAWQA Project is the largest component of the NWQP. 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 2018) accomplishments and planned (fiscal year 2019) activities are listed below:

  • Collected 1,880 water-quality samples at 111 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 FY17 including a national-scale comparison of pesticide concentration data to applicable human health and aquatic life benchmarks, and the computation of  water-quality loads from coastal rivers, large inland rivers, and small stream sites representative of urban, agricultural, or reference conditions. FY17 data and information were posted on the USGS Water Quality Tracking website. 

  • Water-quality models based on the SPAtailly Referenced Regressions On Watershed attributes (SPARROW) modeling framework 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. Model documentation for all models will be published in FY19. 

  • Released USGS Circular 1433, which summarizes results of a systematic national study done in important agricultural areas across the Nation to improve understanding of field-scale and watershed-scale hydrologic processes and their influence on the fate of individual chemicals in the environment and overall water quality. The goals of the study were to understand the connections among agricultural activities, hydrology, and chemical transport. Findings from the study are used by land and water resource managers at the Federal (USDA, NRCS, EPA), State, and local levels to inform management decisions and to help set expectations for the protection and improvement of water quality, which can result from changes in agricultural management and policy decisions. Such management and policy decisions collectively represent the investment of tens of billions of dollars to mitigate or reverse the adverse effects of agricultural activities on the Nation's water quality.

  • Released USGS Circular 1437, which summarizes findings on processes that influence nutrient effects on stream ecosystems and how nutrient enrichment can alter algal and invertebrate communities in agricultural streams. These findings are relevant to local, State, regional, and national decision-makers involved in efforts to (1) better understand the influence of nutrients on agricultural streams, (2) develop nutrient criteria for streams and rivers, (3) reduce nutrients to streams and downstream receiving waters, and (4) develop tools for tracking nutrient and biological conditions following nutrient reduction strategies. Excess nutrients have a major economic impact—causing an estimated $2.2 billion per year in damages related to recreational water usage, waterfront real estate, and drinking water treatment. Findings from this report can be used by land and water resource managers to reduce the impacts of agricultural activities on water quality and stream health. 

  • Released three journal articles and a fact sheet documenting results of the Midwest 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 100 small streams in 11 Midwestern states. 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. Also released an interactive tool for learning about pesticides, nutrients, and the overall health of Midwest and Southeast streams. The Results Viewer shows results for key stressor and ecological metrics as color-coded symbols on a map or as a “scorecard” with all metrics for a site, and the data can be viewed as time series at the sites. Water and sediment-quality data can be downloaded for sites in the Midwest and the other four regions studied by RSQA.

  • Collected groundwater-quality samples at 280 groundwater wells in 10 trend 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. The interactive website "Decadal Change in Groundwater Quality" underwent major revisions to increase both the number of networks and the time span of results displayed on the website and now includes results of sampling over three decades, and results from more than 1,700 wells in 73 networks.

  • Released four Fact Sheets that summarize groundwater-quality assessments of the Rio Grande aquifer system (southwestern U.S.), the Glacial aquifer system (northern U.S.), the Cambrian-Ordovician aquifer system (north central U.S.), and the Piedmont and Blue Ridge crystalline-rock aquifers (eastern U.S.). Almost 400 deep public-supply wells were sampled across these four Principal Aquifers and groundwater samples were analyzed for hundreds of water-quality constituents.

  • Released updated information in a searchable online database of Health-Based Screening Levels (HBSLs) for sources of drinking water. All HBSL values in the database were updated to reflect the U.S. Environmental Protection Agency’s (EPA) most recent methods and exposure assumptions for establishing drinking-water guidelines. HBSLs were added, changed, or removed for 107 contaminants, including 4 contaminants for which HBSLs were replaced with new EPA Human Health Benchmarks for Pesticides (HHBPs). The update increased the number of contaminants with HBSLs from 155 to 175. 


Gary L Rowe, Jr., PhD

Program Coordinator, National Water Quality Program
Water Resources Mission Area
Phone: 303-236-1461

Patty Toccalino, Ph.D.

Deputy Program Coordinator, National Water Quality Program
Water Resources Mission Area
Phone: 916-278-3090