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Groundwater Quality in the East: The Piedmont and Blue Ridge Crystalline-Rock Aquifers
A regional assessment of untreated groundwater in the Piedmont and Blue Ridge crystalline-rock aquifers, which includes parts of 11 states across the contiguous United States, is now available from the U.S. Geological Survey.
The Piedmont and Blue Ridge crystalline-rock aquifers, together with the other rock types in the Piedmont and Blue Ridge regions, rank second in the nation as a source of groundwater for private domestic supply, providing about 360 million gallons per day for this use. These aquifers are also an important source of public supply, and about 92 million gallons per day are pumped for that use. The aquifer underlies an area with a population of more than 25 million. Urban areas within the boundaries of the aquifers include Atlanta, Georgia; Charlotte, North Carolina; and suburbs of Richmond, Virginia; Washington, D.C.; Baltimore, Maryland; and Philadelphia, Pennsylvania.
Scientists tested for hundreds of water-quality constituents and characteristics in samples of untreated groundwater from 60 public-supply wells throughout the aquifer. Radioactive constituents, including radon and gross-alpha activity, were measured in groundwater at a concentration greater than a human-health benchmark (defined as a “high concentration”) in about 30 percent of the study area. Most of the radioactivity in groundwater comes from the decay of isotopes of uranium and thorium that are naturally present in minerals found in aquifers. Other inorganic constituents, notably manganese, were detected at high concentrations in groundwater in about 5 percent of the study area. Manmade organic constituents, including pesticides and volatile organic compounds, were not detected in groundwater at high concentrations.
Between 2013 and 2022, the USGS National Water Quality Assessment (NAWQA) Project is assessing the quality of the nation’s groundwater by sampling about 2,300 shallow wells and 1,400 deep public-supply wells for a broad range of water-quality constituents. Information on USGS regional aquifer assessments can be found in a USGS Featured Story.
For more information on the Glacial aquifer system, contact Bruce Lindsey, [log in to unmask]
Explore USGS interactive maps—
Decadal Trends in the Quality of the Nation’s Groundwater:
https://nawqatrends.wim.usgs.g