NAWQA—Tracking and Forecasting the Nation's Water Quality
What’s in the water? And is water quality getting better or worse?
Surface-Water Quality and Ecology
Drinking water, irrigation, recreation, habitat—learn about water quality of our streams and rivers, how it’s changing, and why that matters
Groundwater Quality
Do you drink water from a well? Find out about the quality of this invisible resource used for drinking water by almost half the Nation’s population.
Water-Quality Topics
Read about USGS water-quality science on a range of topics, from pesticides to PAHs, from radionuclides to redox
New Water-Quality Directions
The USGS Water Resources Mission Area is updating current water programs to meet 21st century water-resource challenges.
Our surface water, groundwater, and aquatic ecosystems are priceless resources, used by people across the Nation for drinking, irrigation, industry, and recreation. The National Water-Quality Assessment (NAWQA) Project is a leading source of scientific data and knowledge for development of science-based policies and management strategies to improve and protect our water resources.
Quick Links
Looking for data? Maps? Use these links to quickly access some of the most frequently visited USGS web pages on water quality.
In 1991, Congress established the National Water-Quality Assessment (NAWQA) Project to address where, when, why, and how the Nation's water quality has changed, or is likely to change in the future, in response to human activities and natural factors. Since then, NAWQA has produced scientific data and knowledge that is used by national, regional, state, and local agencies to develop science-based policies and management strategies to improve and protect water resources used for drinking water, recreation, irrigation, energy development, and ecosystem needs. A prominent feature of NAWQA is the development of long-term consistent and comparable information on streams, rivers, ground water, and aquatic systems. The NAWQA Project is designed to answer these questions:
- What is the current condition of our Nation's streams, rivers, and groundwater?
- How are these conditions changing over time?
- How do natural features and human activities affect these conditions, and where are those effects most pronounced?
NAWQA Water-Quality Research
SURFACE WATER AND ECOLOGY
Water Quality and Ecology of Small Streams (RSQA)
The Regional Stream Quality Assessment (RSQA) is studying the relations between stressors (chemical and physical) and stream ecology (fish, algae, and aquatic invertebrates) at small streams in five large regions of the United States. Users can access an online mapping tool to compare water quality at small streams across a region, see scorecards that summarize stream health at each stream site, and download data for hundreds of chemical compounds.
Water Quality in the Nation's Streams and Rivers: Current Conditions and Long-Term Trends
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. An online water-quality tracking tool shows graphs of pesticides, nutrients, and sediment in streams, and users can download data for a streams and rivers across the country; the tool is updated annually. The online water-quality trends mapping tool allows users to visualize trends in water chemistry (nutrients, pesticides, sediment, carbon, and salinity) and aquatic ecology (fish, invertebrates, and algae).
SPARROW modeling: Estimating nutrient, sediment, and dissolved solids transport
SPARROW (SPAtially Referenced Regression On Watershed attributes) models estimate the amount of a contaminant transported from inland watersheds to larger water bodies by linking monitoring data with information on watershed characteristics and contaminant sources. Users can explore relations between human activities, natural processes, and contaminant transport using interactive mappers.
GROUNDWATER
Groundwater Quality: Current Conditions and Changes Through Time
Scientists are characterizing groundwater quality in principal aquifers, the primary source of the Nation's groundwater used for drinking. Concentrations of inorganic constituents, such as arsenic and nitrate, and organic constituents, such as pesticides and volatile organic compounds, are compared to benchmarks established for the protection of human health. Users can access an online tool to see how concentrations of pesticides, nutrients, metals, and organic contaminants in groundwater are changing during decadal periods across the Nation, and see in real time how chemical properties of groundwater at some sites are fluctuating.
Groundwater Quality: Predictions for Unmonitored Areas
Groundwater hydrologists are developing statistical models that predict where a contaminant is likely to occur in groundwater and at what concentration. These models extrapolate groundwater quality in areas and at depths where groundwater has not yet been sampled. Users can see predicted contaminant concentrations in map view, and—for some aquifers—in 3-D.
SURFACE WATER/GROUNDWATER INTERACTION
Groundwater/Surface-Water Interaction
Surface water and groundwater are intimately connected and are constantly interacting. The Integrated Watershed Studies team is quantifying how water and chemicals move between the landscape, streams and rivers, and groundwater. Learn how the quantity and quality of surface water and groundwater are likely to change in response to changes in climate, land use, and best management practices.
NAWQA — The First Two Decades
From 1991-2001, the NAWQA Project conducted interdisciplinary assessments, including water chemistry, hydrology, land use, stream habitat, and aquatic life, and established a baseline understanding of water-quality conditions in 51 of the Nation's river basins and aquifers, referred to as Study Units.
From 2001-2012, NAWQA focused on specific water-quality topics of national interest, such as pesticides, nutrients, and aquatic ecology, as well as continuing to monitor and assess 42 of the Study Units.
► Learn about the first two decades of NAWQA research and access information and publications about the quality of the Nation's surface-water and groundwater resources.
How do we do it?
Find methods used by NAWQA to assesses the current quality of our surface water and groundwater.
► Documentation on water-quality sample collection methods developed by NAWQA.
Explore Related Topics on Water-Quality Research
RELATIONS BETWEEN LAND USE AND WATER QUALITY
Urban Land Use and Water Quality
Agricultural Contamination
CONTAMINANTS IN WATER
Arsenic and Drinking Water
Chloride, salinity, and dissolved solids
Emerging contaminants (including pharmaceuticals and hormones)
Mercury
Metals and Other Trace Elements
Nutrients and Eutrophication
National Atmospheric Deposition Program (NADP)
Pesticides and Water Quality
Coal-Tar-Based Pavement Sealcoat, PAHs, and Environmental Health
Radionuclides
Sediment-associated contaminants
Volatile organic compounds (VOCs) (including MTBE)
DRINKING WATER ISSUES
Corrosivity
Domestic (private) supply wells
Public-supply wells
Drinking-water taste and odor
Water-Quality Benchmarks for Contaminants
Drinking Water and Source Water Research
RELATIONS TO AQUATIC LIFE
Stream ecology
Mercury
Streamflow Alteration
NWQP Research on Harmful Algal Blooms (HABs)
TRENDS IN WATER QUALITY
Water-quality trends
Water-quality trends from lake sediment cores
PROCESSES
Oxidation/Reduction (Redox)
Groundwater Age
► Confused by some of the water-quality terms? Find the definitions and explanations you're looking for in the Water-Quality Glossary.
Learn more about some of the research associated with the National Water Quality Assessment project.
Water-Quality Benchmarks for Contaminants
New Water-Quality Directions
NWQP Research on Harmful Algal Blooms (HABs)
Nutrients and Eutrophication
Drinking Water and Source Water Research
Urban Land Use and Water Quality
NWQP Water-Quality Topics
Emerging Contaminants
Groundwater Quality Research
Groundwater/Surface-Water Interaction
Hydraulic Fracturing
Agriculture and the Quality of the Nation's Waters
Web applications and downloadable data related to NAWQA water-quality research.
Changes in anthropogenic influences on streams and rivers in the conterminous U.S. over the last 40 years, derived for 16 data themes
Data Release for Secondary Hydrogeologic Regions of the Conterminous United States (ver. 2.0, June 2022)
Input and results from a boosted regression tree (BRT) model relating base flow nitrate concentrations in the Chesapeake Bay watershed to catchment characteristics (1970-2013)
Concentrations of Pesticide, Pharmaceutical, and Organic Wastewater Contaminants from a Multi-Regional Assessment of Wadeable USA Streams, 2014-17
Pesticide and transformation product concentrations and risk quotients in U.S. headwater streams
Data set for an ecological risk assessment of Firpronil compounds in US streams
Dissolved Pesticides in Weekly Water Samples from the NAWQA Regional Stream Quality Assessments (2013-2017)
Pesticide Toxicity Index (PTI) and maximum Toxic Unit (TUmax) scores and information for fish, cladocerans, and benthic invertebrates from water samples collected at National Water Quality Network sites during Water Years 2013-2017
Datasets from Groundwater-Quality and Select Quality-Control Data from the National Water-Quality Assessment Project, January through December 2016, and Previously Unpublished Data from 2013 to 2015
Data for Fluoride Occurrence in United States Groundwater
Concentrations of pesticides associated with streambed sediment and biofilm in California streams, 2017
Hydrophobic (sediment-associated) pesticides were measured in sediment samples collected from 82 wadeable streams and in biofilm in 54 of those streams in the Central California Foothills and Coastal Mountains ecoregion.115 current-use and 3 legacy pesticides were measured in stream sediment; 93 of the current-use pesticides and the same 3 legacy pesticides were measured in biofilm. On average 4 t
Urban sediment and fallout radionuclide input characteristics of Dead Run watershed in Catonsville, Maryland for 2017-2018 (ver. 1.1, March 2020)
Pesticides in Daily and Weekly Water Samples from the NAWQA Midwest and Southeast Stream Quality Assessments (2013-2014)
The NAWQA project publishes reports that describe water-quality and ecological conditions; whether conditions are changing over time; and how natural features and human activities affect these conditions.
The most recent publications and selected national-scale reports are listed here.
Flow modification in the Nation’s streams and rivers
Is there an urban pesticide signature? Urban streams in five U.S. regions share common dissolved-phase pesticides but differ in predicted aquatic toxicity
Groundwater quality in the Colorado Plateaus aquifers, western United States
Groundwater quality in the Edwards-Trinity aquifer system
Groundwater quality in selected Stream Valley aquifers, western United States
Groundwater-quality and select quality-control data from the National Water-Quality Assessment Project, January 2017 through December 2019
Inclusion of pesticide transformation products is key to estimating pesticide exposures and effects in small U.S. streams
Nitrogen and phosphorus sources and delivery from the Mississippi/Atchafalaya River Basin: An update using 2012 SPARROW models
Multi-region assessment of chemical mixture exposures and predicted cumulative effects in USA wadeable urban/agriculture-gradient streams
Chemical-contaminant mixtures are widely reported in large stream reaches in urban/agriculture-developed watersheds, but mixture compositions and aggregate biological effects are less well understood in corresponding smaller headwaters, which comprise most of stream length, riparian connectivity, and spatial biodiversity. During 2014–2017, the U.S. Geological Survey (USGS) measured 389 unique orga
Changing climate drives future streamflow declines and challenges in meeting water demand across the southwestern United States
Three-dimensional distribution of residence time metrics in the glaciated United States using metamodels trained on general numerical models
Lithium in groundwater used for drinking-water supply in the United States
The occurrence and distribution of strontium in U.S. groundwater
Interactive mappers and web applications related to NAWQA water-quality research.
Groundwater Quality: Decadal Change
Almost one-half of the U.S. population rely on groundwater for their water supply, and demand for groundwater for public supply, irrigation, and agriculture continues to increase. This mapper shows how concentrations of pesticides, nutrients, metals, and organic contaminants in groundwater are changing during decadal periods across the Nation.
RSPARROW
RSPARROW, now available on the USGS GitLab repository, provides the first open-source version of the USGS SPARROW water-quality model
SPARROW Modeling Program
SPARROW is a popular watershed modeling technique, distributed by the USGS, that estimates the amount of a contaminant transported from inland watersheds to larger water bodies by linking monitoring data with information on watershed characteristics and contaminant sources.
Isotopic tracers in fish in Northeast provide clue to mercury sources
Isotopes of mercury in fish can indicate the source of that mercury, reports a new study from the USGS Regional Stream Quality Assessment.
Our surface water, groundwater, and aquatic ecosystems are priceless resources, used by people across the Nation for drinking, irrigation, industry, and recreation. The National Water-Quality Assessment (NAWQA) Project is a leading source of scientific data and knowledge for development of science-based policies and management strategies to improve and protect our water resources.
Quick Links
Looking for data? Maps? Use these links to quickly access some of the most frequently visited USGS web pages on water quality.
In 1991, Congress established the National Water-Quality Assessment (NAWQA) Project to address where, when, why, and how the Nation's water quality has changed, or is likely to change in the future, in response to human activities and natural factors. Since then, NAWQA has produced scientific data and knowledge that is used by national, regional, state, and local agencies to develop science-based policies and management strategies to improve and protect water resources used for drinking water, recreation, irrigation, energy development, and ecosystem needs. A prominent feature of NAWQA is the development of long-term consistent and comparable information on streams, rivers, ground water, and aquatic systems. The NAWQA Project is designed to answer these questions:
- What is the current condition of our Nation's streams, rivers, and groundwater?
- How are these conditions changing over time?
- How do natural features and human activities affect these conditions, and where are those effects most pronounced?
NAWQA Water-Quality Research
SURFACE WATER AND ECOLOGY
Water Quality and Ecology of Small Streams (RSQA)
The Regional Stream Quality Assessment (RSQA) is studying the relations between stressors (chemical and physical) and stream ecology (fish, algae, and aquatic invertebrates) at small streams in five large regions of the United States. Users can access an online mapping tool to compare water quality at small streams across a region, see scorecards that summarize stream health at each stream site, and download data for hundreds of chemical compounds.
Water Quality in the Nation's Streams and Rivers: Current Conditions and Long-Term Trends
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. An online water-quality tracking tool shows graphs of pesticides, nutrients, and sediment in streams, and users can download data for a streams and rivers across the country; the tool is updated annually. The online water-quality trends mapping tool allows users to visualize trends in water chemistry (nutrients, pesticides, sediment, carbon, and salinity) and aquatic ecology (fish, invertebrates, and algae).
SPARROW modeling: Estimating nutrient, sediment, and dissolved solids transport
SPARROW (SPAtially Referenced Regression On Watershed attributes) models estimate the amount of a contaminant transported from inland watersheds to larger water bodies by linking monitoring data with information on watershed characteristics and contaminant sources. Users can explore relations between human activities, natural processes, and contaminant transport using interactive mappers.
GROUNDWATER
Groundwater Quality: Current Conditions and Changes Through Time
Scientists are characterizing groundwater quality in principal aquifers, the primary source of the Nation's groundwater used for drinking. Concentrations of inorganic constituents, such as arsenic and nitrate, and organic constituents, such as pesticides and volatile organic compounds, are compared to benchmarks established for the protection of human health. Users can access an online tool to see how concentrations of pesticides, nutrients, metals, and organic contaminants in groundwater are changing during decadal periods across the Nation, and see in real time how chemical properties of groundwater at some sites are fluctuating.
Groundwater Quality: Predictions for Unmonitored Areas
Groundwater hydrologists are developing statistical models that predict where a contaminant is likely to occur in groundwater and at what concentration. These models extrapolate groundwater quality in areas and at depths where groundwater has not yet been sampled. Users can see predicted contaminant concentrations in map view, and—for some aquifers—in 3-D.
SURFACE WATER/GROUNDWATER INTERACTION
Groundwater/Surface-Water Interaction
Surface water and groundwater are intimately connected and are constantly interacting. The Integrated Watershed Studies team is quantifying how water and chemicals move between the landscape, streams and rivers, and groundwater. Learn how the quantity and quality of surface water and groundwater are likely to change in response to changes in climate, land use, and best management practices.
NAWQA — The First Two Decades
From 1991-2001, the NAWQA Project conducted interdisciplinary assessments, including water chemistry, hydrology, land use, stream habitat, and aquatic life, and established a baseline understanding of water-quality conditions in 51 of the Nation's river basins and aquifers, referred to as Study Units.
From 2001-2012, NAWQA focused on specific water-quality topics of national interest, such as pesticides, nutrients, and aquatic ecology, as well as continuing to monitor and assess 42 of the Study Units.
► Learn about the first two decades of NAWQA research and access information and publications about the quality of the Nation's surface-water and groundwater resources.
How do we do it?
Find methods used by NAWQA to assesses the current quality of our surface water and groundwater.
► Documentation on water-quality sample collection methods developed by NAWQA.
Explore Related Topics on Water-Quality Research
RELATIONS BETWEEN LAND USE AND WATER QUALITY
Urban Land Use and Water Quality
Agricultural Contamination
CONTAMINANTS IN WATER
Arsenic and Drinking Water
Chloride, salinity, and dissolved solids
Emerging contaminants (including pharmaceuticals and hormones)
Mercury
Metals and Other Trace Elements
Nutrients and Eutrophication
National Atmospheric Deposition Program (NADP)
Pesticides and Water Quality
Coal-Tar-Based Pavement Sealcoat, PAHs, and Environmental Health
Radionuclides
Sediment-associated contaminants
Volatile organic compounds (VOCs) (including MTBE)
DRINKING WATER ISSUES
Corrosivity
Domestic (private) supply wells
Public-supply wells
Drinking-water taste and odor
Water-Quality Benchmarks for Contaminants
Drinking Water and Source Water Research
RELATIONS TO AQUATIC LIFE
Stream ecology
Mercury
Streamflow Alteration
NWQP Research on Harmful Algal Blooms (HABs)
TRENDS IN WATER QUALITY
Water-quality trends
Water-quality trends from lake sediment cores
PROCESSES
Oxidation/Reduction (Redox)
Groundwater Age
► Confused by some of the water-quality terms? Find the definitions and explanations you're looking for in the Water-Quality Glossary.
Learn more about some of the research associated with the National Water Quality Assessment project.
Water-Quality Benchmarks for Contaminants
New Water-Quality Directions
NWQP Research on Harmful Algal Blooms (HABs)
Nutrients and Eutrophication
Drinking Water and Source Water Research
Urban Land Use and Water Quality
NWQP Water-Quality Topics
Emerging Contaminants
Groundwater Quality Research
Groundwater/Surface-Water Interaction
Hydraulic Fracturing
Agriculture and the Quality of the Nation's Waters
Web applications and downloadable data related to NAWQA water-quality research.
Changes in anthropogenic influences on streams and rivers in the conterminous U.S. over the last 40 years, derived for 16 data themes
Data Release for Secondary Hydrogeologic Regions of the Conterminous United States (ver. 2.0, June 2022)
Input and results from a boosted regression tree (BRT) model relating base flow nitrate concentrations in the Chesapeake Bay watershed to catchment characteristics (1970-2013)
Concentrations of Pesticide, Pharmaceutical, and Organic Wastewater Contaminants from a Multi-Regional Assessment of Wadeable USA Streams, 2014-17
Pesticide and transformation product concentrations and risk quotients in U.S. headwater streams
Data set for an ecological risk assessment of Firpronil compounds in US streams
Dissolved Pesticides in Weekly Water Samples from the NAWQA Regional Stream Quality Assessments (2013-2017)
Pesticide Toxicity Index (PTI) and maximum Toxic Unit (TUmax) scores and information for fish, cladocerans, and benthic invertebrates from water samples collected at National Water Quality Network sites during Water Years 2013-2017
Datasets from Groundwater-Quality and Select Quality-Control Data from the National Water-Quality Assessment Project, January through December 2016, and Previously Unpublished Data from 2013 to 2015
Data for Fluoride Occurrence in United States Groundwater
Concentrations of pesticides associated with streambed sediment and biofilm in California streams, 2017
Hydrophobic (sediment-associated) pesticides were measured in sediment samples collected from 82 wadeable streams and in biofilm in 54 of those streams in the Central California Foothills and Coastal Mountains ecoregion.115 current-use and 3 legacy pesticides were measured in stream sediment; 93 of the current-use pesticides and the same 3 legacy pesticides were measured in biofilm. On average 4 t
Urban sediment and fallout radionuclide input characteristics of Dead Run watershed in Catonsville, Maryland for 2017-2018 (ver. 1.1, March 2020)
Pesticides in Daily and Weekly Water Samples from the NAWQA Midwest and Southeast Stream Quality Assessments (2013-2014)
The NAWQA project publishes reports that describe water-quality and ecological conditions; whether conditions are changing over time; and how natural features and human activities affect these conditions.
The most recent publications and selected national-scale reports are listed here.
Flow modification in the Nation’s streams and rivers
Is there an urban pesticide signature? Urban streams in five U.S. regions share common dissolved-phase pesticides but differ in predicted aquatic toxicity
Groundwater quality in the Colorado Plateaus aquifers, western United States
Groundwater quality in the Edwards-Trinity aquifer system
Groundwater quality in selected Stream Valley aquifers, western United States
Groundwater-quality and select quality-control data from the National Water-Quality Assessment Project, January 2017 through December 2019
Inclusion of pesticide transformation products is key to estimating pesticide exposures and effects in small U.S. streams
Nitrogen and phosphorus sources and delivery from the Mississippi/Atchafalaya River Basin: An update using 2012 SPARROW models
Multi-region assessment of chemical mixture exposures and predicted cumulative effects in USA wadeable urban/agriculture-gradient streams
Chemical-contaminant mixtures are widely reported in large stream reaches in urban/agriculture-developed watersheds, but mixture compositions and aggregate biological effects are less well understood in corresponding smaller headwaters, which comprise most of stream length, riparian connectivity, and spatial biodiversity. During 2014–2017, the U.S. Geological Survey (USGS) measured 389 unique orga
Changing climate drives future streamflow declines and challenges in meeting water demand across the southwestern United States
Three-dimensional distribution of residence time metrics in the glaciated United States using metamodels trained on general numerical models
Lithium in groundwater used for drinking-water supply in the United States
The occurrence and distribution of strontium in U.S. groundwater
Interactive mappers and web applications related to NAWQA water-quality research.
Groundwater Quality: Decadal Change
Almost one-half of the U.S. population rely on groundwater for their water supply, and demand for groundwater for public supply, irrigation, and agriculture continues to increase. This mapper shows how concentrations of pesticides, nutrients, metals, and organic contaminants in groundwater are changing during decadal periods across the Nation.
RSPARROW
RSPARROW, now available on the USGS GitLab repository, provides the first open-source version of the USGS SPARROW water-quality model
SPARROW Modeling Program
SPARROW is a popular watershed modeling technique, distributed by the USGS, that estimates the amount of a contaminant transported from inland watersheds to larger water bodies by linking monitoring data with information on watershed characteristics and contaminant sources.
Isotopic tracers in fish in Northeast provide clue to mercury sources
Isotopes of mercury in fish can indicate the source of that mercury, reports a new study from the USGS Regional Stream Quality Assessment.