National Water-Quality Assessment (NAWQA)

Featured: Deciphering the U.S. urban stream pesticide signature

Featured: Deciphering the U.S. urban stream pesticide signature

new USGS study reports that 16 dissolved pesticides were consistently detected in small streams in 16 urban centers across five regions of the United States.

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Featured: Potential pesticide toxicity to aquatic life is widespread

Featured: Potential pesticide toxicity to aquatic life is widespread

new USGS study of pesticides in U.S. rivers and streams reports that, on average, 17 pesticides were detected at least once at the 74 river and stream sites sampled 12 to 24 times per year during 2013–2017.

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Quick Links

Looking for data? Maps? Use these links to quickly access some of the most frequently visited USGS web pages on water quality.

New Water-Quality Directions

Real-Time Water-Quality Data

Water-Quality Watch

Sediment Data Portal

Pesticide Use Maps and Data

Health-Based Screening Levels (HBSLs)


Science Center Objects

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.

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


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 Rivers and Streams: 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).

Modeling Contaminant Loads in Rivers and Streams (SPARROW)
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

NAWQA surface water slides

From left: Aquatic sampling during Southeast Stream Quality Assessment; velocity measurement at Truckee River, Nevada; wrestling with cages of fathead minnows in Goodwater Creek, Missouri, during high flow. 


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.

NAWQA groundwater slides

From left: measuring groundwater salinity in Georgia; collecting groundwater samples for laboratory analysis in Florida; sampling shallow groundwater wells for an agricultural land-use study in Georgia; collecting groundwater samples in Nevada. 



Integrated Watershed Studies
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 surface water-groundwater interaction

From left: Installing shallow groundwater wells at ephemeral ponds; the Alapaha River , a "losing" stream at low flow; marking groundwater seeps. (Credit: Alan Cressler, USGS)



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.


Adam Mumford sampling a stream in PA

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


     Chloride and salinity
     Emerging contaminants (including pharmaceuticals and hormones)
     National Atmospheric Deposition Program (NADP)
     Polycyclic aromatic hydrocarbons (PAHs) and coal-tar sealant
     Sediment-associated contaminants
     Volatile organic compounds (VOCs), including MTBE

     Domestic (private) supply wells
     Public-supply wells
     Drinking-water taste and odor
     Water-quality benchmarks
     Drinking-water and source-water research

     Stream ecology
     Mercury in stream ecosystems
     Flow alteration
     Harmful algal blooms (HABs)

     Water-quality trends
     Water-quality trends from lake sediment cores 

Oxidation/Reduction (Redox)
     Groundwater age-dating


►  Confused by some of the water-quality terms?  Find the definitions and explanations you're looking for in the Water-Quality Glossary.