National Water-Quality Assessment (NAWQA) Program

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Water-Quality Assessments of Principal Aquifers

A major focus of the NAWQA Program in its second decade (2002-2013) is on regional- and national-scale assessments of groundwater-quality status and trends in principal aquifers. The U.S. Geological Survey Office of Groundwater has identified 62 principal aquifers in the U.S. (U.S. Geological Survey, 2003). About 1/3 of the Nation's principal aquifers are the focus of water-quality assessments at the regional scale by NAWQA.

The NAWQA framework for principal aquifer assessments considers the physical setting of the aquifer, in addition to its susceptibility and vulnerability to contamination.

More information (USGS Fact Sheet 2005-3013, PDF, Adobe reader is freely available to read a PDF)

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Variations in groundwater quality among aquifers

Map of principal aquifers with links to more information.Link to regional assessment of ground-water quality in principal volcanic aquifers of the Western United States.Link to regional assessment of ground-water quality in principal volcanic aquifers of the Western United States.Link to regional assessment of ground-water quality quality in the Basin and Range, Rio Grande, Coastal Basins, and Central Valley Aquifer Systems of the Southwestern United States.Link to regional assessment of ground-water quality in the Basin and Range, Rio Grande, Coastal Basins, and Central Valley Aquifer Systems of the Southwestern United States.Link to regional assessment of ground-water quality in the Basin and Range, Rio Grande, Coastal Basins, and Central Valley Aquifer Systems of the Southwestern United States.Link to regional assessment of ground-water quality in principal volcanic aquifers of the Western United StatesLink to regional assessment of ground-water quality in the Glacial Aquifer System.Link to regional Assessment of Groundwater Quality in the Mississippi Embayment-Texas Coastal Uplands Aquifer System, Coastal Lowlands Aquifer System, and the Edwards-Trinity Aquifer System.Link to regional Assessment of Groundwater Quality in the Mississippi Embayment-Texas Coastal Uplands Aquifer System, Coastal Lowlands Aquifer System, and the Edwards-Trinity Aquifer System.Link to regional Assessment of Groundwater Quality in the Mississippi Embayment-Texas Coastal Uplands Aquifer System, Coastal Lowlands Aquifer System, and the Edwards-Trinity Aquifer System.Link to regional assessment of ground-water quality in the Floridan, Biscayne, and Surficial Aquifer Systems.Link to regional assessment of ground-water quality in the Floridan, Biscayne, and Surficial Aquifer Systems.Link to regional assessment of ground-water quality in the Floridan, Biscayne, and Surficial Aquifer Systems.Link to regional assessment of ground-water quality in the Piedmont and Valley and Ridge Aquifers.Link to regional assessment of ground-water quality in the Piedmont, Early Mesozoic, and Valley and Ridge Aquifers.Link to regional assessment of ground-water quality in the Northern Atlantic Coastal Plain aquifer system.Link to regional assessment of ground-water quality in the New England crystalline-rock aquifers.Link to regional assessment of ground-water quality in the Glacial Aquifer System.The web page for the Cambrian/Ordovician aquifer is still being developed.Link to regional assessment of ground-water quality in the Piedmont and Valley and Ridge Aquifers.The web page for the Denver Basin aquifer is still being developed.Link to regional assessment of ground-water quality in the High Plains aquifer system.Link to regional assessment of ground-water quality in the Basin and Range, Rio Grande, Coastal Basins, and Central Valley Aquifer Systems of the Southwestern United States.

Larger map with links to more information || Text links to more information about principal aquifers shown on the above map


What is a Principal Aquifer?

Principal Aquifer Map

Definition: A principal aquifer is defined as a regionally extensive aquifer or aquifer system that has the potential to be used as a source of potable water. An aquifer is a geologic formation, a group of formations, or a part of a formation that contains sufficient saturated permeable material to yield significant quantities of water to wells and springs. Aquifers are often combined into aquifer systems. (U.S. Geological Survey, 2003).

Primary Lithologies of Select Principal Aquifers

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Page Last Modified: Tuesday, 04-Mar-2014 14:45:22 EST