National Water-Quality Assessment (NAWQA) Project

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Regional Assessment of Groundwater Quality in the
Piedmont and Valley and Ridge Aquifers

Map of Piedmont and Valley and Ridge Aquifers.The aquifers in the Piedmont and Valley and Ridge are part of the National Water-Quality Assessment program assessment of status and trends of groundwater. In the physiographic region of the Piedmont, Blue Ridge, and Valley and Ridge, there are 5 principal aquifers. The Piedmont and Blue Ridge crystalline-rock aquifers, Piedmont and Blue Ridge carbonate-rock aquifers, and Early Mesozoic basin aquifers are located in the Piedmont and Blue Ridge. In the Valley and Ridge, the principal aquifers are Valley and Ridge aquifers and the Valley and Ridge carbonate-rock aquifers. These aquifers are contiguous fractured-bedrock aquifers that are located in the eastern United States, with a combined area of 154,000 square miles. These 5 aquifers are all included as a part of the regional assessment of water quality in fractured-bedrock aquifers. Because of the lack of data in the Blue Ridge, the study is referred to as the Piedmont and Valley and Ridge aquifer study.  Total water use from these aquifers in 2000 was 669 million gallons per day (USGS Circular-1279, Maupin and Barber, 2005).

Topics selected for the assessment of water quality:

  • Nitrate, pesticides, VOCs, and radon in groundwater of the Piedmont (SIR 2006-5104)
  • Nitrate and phosphorus in ground-water and stream base flow in the Piedmont and Valley and Ridge (SIR 2010-5176)
  • Nitrate, pesticides, VOCs, and radon in groundwater of the Valley and Ridge (SIR 2011-5115)
  • Comparison of natural and anthropogenic compounds in various geologic terranes (geologic belts) within the Piedmont aquifers (description)

Featured publications
(View complete list)

  • The sources, fate, and transport of phosphorus from groundwater to streams were evaluated using water-quality data collected from 1991 through 2007 in paired networks of groundwater and streams in different hydrogeologic and land-use settings of the Piedmont, Blue Ridge, and Valley and Ridge Physiographic Provinces in the eastern United States. Geochemical controls effectively limit phosphorus transport to streams in areas underlain by carbonate rocks and elevated concentrations of phosphorus in stream base flow are presumably derived from local anthropogenic sources. In crystalline and siliciclastic settings, however, phosphorus from mineral or human sources may be effectively transported by groundwater and contribute a substantial fraction to base-flow stream loads. Mineral dissolution was identified as the dominant source of phosphorus in the groundwater and streams in these settings. The potential for geologic contributions of phosphorus to water may be an important watershed management consideration as concentrations of phosphorus in streams at base flow and in groundwater commonly exceed ecological criteria for streams in the study area. (Download Report)

General Information

Informational handout about the Piedmont and Valley and Ridge aquifer studies (PDF format, 1Mb)

Piedmont and Valley and Ridge aquifers Included in National Study of Carbonate Aquifers

Groundwater in carbonate rocks in the Piedmont and Valley and Ridge aquifers also are studied as part of a broader NAWQA study of most of the Nation’s carbonate aquifer systems. Findings from this study will provide useful comparisons and enhanced understanding to the current work in the Piedmont and Valley and Ridge aquifers. This national study is based on samples from more than one thousand wells or springs, including those used for monitoring, domestic purposes, and public supply. (SIR 2008-5240)

Hydrogeology of the Piedmont and Valley and Ridge aquifer system—Ground Water Atlas of the United States

For more information, contact:
Bruce Lindsey, Hydrologist

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