National Water Quality Program


The National Water Quality Program provides an understanding of water-quality conditions; whether conditions are getting better or worse over time; and how natural features and human activities affect those conditions.

More about this program

Featured Study: Insights into changes in chloride in streams

Featured Study: Insights into changes in chloride in streams

A joint USEPA-USGS study finds that integrating water-quality sampling approaches can provide insight into changing chloride concentrations in U.S. streams and rivers.

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Featured Study: Potential lead solubility in groundwater

Featured Study: Potential lead solubility in groundwater

About one-third of more than 8,300 wells tested across the U.S. had groundwater with chemical characteristics that could cause lead, if present in plumbing, to leach into tap water at levels above the EPA Action Level.

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Date published: September 12, 2019

Groundwater age-dating simplified

A new USGS report documents a simple method to classify groundwater age as premodern (recharged before 1953), modern (recharge in 1953 or later), or a mix of the two. The method—tritium-based age classification, or TBAC—requires just a single measurement of tritium, along with knowledge of sample date and location...

Date published: August 20, 2019

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

Date published: August 9, 2019

USGS National Water Quality Laboratory protocols effective at minimizing false-positive pesticide results

A new analysis of USGS National Water Quality Laboratory (NWQL) quality-control protocols finds that “false-positive” and “false negative” results—reporting that a compound is present in a sample when it is not or that a compound is not present when it is—are minimal.


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Year Published: 2019

Hydrocarbons in upland groundwater, Marcellus Shale Region, Northeastern Pennsylvania and Southern New York, USA

Water samples from 50 domestic wells located <1 km (proximal) and >1 km (distal) from shale-gas wells in upland areas of the Marcellus Shale region were analyzed for chemical, isotopic, and groundwater-age tracers. Uplands were targeted because natural mixing with brine and hydrocarbons from deep formations is less common in those areas...

McMahon, Peter B.; Lindsey, Bruce D.; Conlon, Matthew D.; Hunt, Andrew G.; Belitz, Kenneth; Jurgens, Bryant; Varela, Brian

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Year Published: 2019

Estimating domestic well locations and populations served in the contiguous U.S. for years 2000 and 2010

Domestic wells provide drinking water supply for approximately 40 million people in the United States. Knowing the location of these wells, and the populations they serve, is important for identifying heavily used aquifers, locations susceptible to contamination, and populations potentially impacted by poor-quality groundwater. The 1990 census was...

Johnson, Tyler D.; Belitz, Kenneth; Lombard, Melissa

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Year Published: 2019

Assessing water-quality changes in U.S. rivers at multiple geographic scales using results from probabilistic and targeted monitoring

Two commonly used approaches for water quality monitoring are probabilistic and targeted. In a probabilistic approach like the US Environmental Protection Agency’s National Rivers and Streams Assessment, monitoring sites are selected using a statistically representative approach. In a targeted approach like that used by many monitoring...

Sprague, Lori A.; Mitchell, Richard M; Pollard, Amina I.; Falcone, James A.