Kenneth Belitz Bruce D. Lindsey 2016 <p>Groundwater provides nearly 50 percent of the Nation’s drinking water. To help protect this vital resource, the U.S. Geological&nbsp;Survey (USGS) National Water-Quality Assessment (NAWQA) Project assesses groundwater quality in aquifers that are&nbsp;important sources of drinking water. The Valley and Ridge and Piedmont and Blue Ridge carbonate-rock&nbsp;aquifers constitute two of the important areas being evaluated.&nbsp;One or more inorganic constituents with human-health benchmarks were detected at high concentrations in about 15 percent of the study area and at moderate concentrations in about 17 percent. Organic constituents were not detected at high concentrations in&nbsp;the study area. One or more organic constituents with human-health benchmarks were detected at moderate concentrations in about 2 percent of the study area.</p> application/pdf 10.3133/fs20163079 en U.S. Geological Survey Groundwater quality in the Valley and Ridge and Piedmont and Blue Ridge carbonate-rock aquifers, eastern United States reports