National Water-Quality Assessment (NAWQA) Program

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Featured Studies
Special studies on source-water and drinking-water quality
Surface-water intakes
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Groundwater-Quality Trends

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Featured New Reports

report thumbnailUse of classes based on redox and groundwater age to characterize the susceptibility of principal aquifers to changes in nitrate concentrations, 1991 to 2010


report thumbnailNumerical model simulations of nitrate concentrations in groundwater using various nitrogen input scenarios, mid-Snake region, south-central Idaho


Groundwater-quality monitoring data collected by NAWQA from many regions of the United States are being synthesized into a national assessment of groundwater-quality trends. Between 1988 and 2000, NAWQA completed groundwater-quality assessments in 51 study areas across the United States. During 2001, NAWQA began resampling many of those well networks on a near-decadal timeframe to determine if groundwater quality has changed over time. A well network is typically 20-30 randomly selected wells designed to examine groundwater quality in a region; in some cases well networks are designed to represent specific land-use practices such as agricultural or urban. To date (2012), 1,235 wells in 56 well networks have been resampled on a near-decadal time period (Lindsey and Rupert, 2012; Rupert, 2005). NAWQA will continue to periodically resample wells.


Featured Interactive Map: Changes of nitrate concentrations in groundwater of the United States


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