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Circular 1360

National Water-Quality Assessment Program

The Quality of Our Nation’s Waters

Water Quality in Principal Aquifers of the United States, 1991–2010

By Leslie A. DeSimone, Peter B. McMahon, and Michael R. Rosen

Thumbnail of and link to report PDF (120.55 MB)Overview

About 130 million people in the United States rely on groundwater for drinking water, and the need for high-quality drinking-water supplies becomes more urgent as our population grows. Although groundwater is a safe, reliable source of drinking water for millions of people nationwide, high concentrations of some chemical constituents can pose potential human-health concerns. Some of these contaminants come from the rocks and sediments of the aquifers themselves, and others are chemicals that we use in agriculture, industry, and day-to-day life. When groundwater supplies are contaminated, millions of dollars can be required for treatment so that the supplies can be usable. Contaminants in groundwater can also affect the health of our streams and valuable coastal waters. By knowing where contaminants occur in groundwater, what factors control contaminant concentrations, and what kinds of changes in groundwater quality might be expected in the future, we can ensure the availability and quality of this vital natural resource in the future.

Major Findings

  • Contaminants from geologic or manmade sources were a potential human-health concern in one of every five wells sampled in the parts of aquifers used for drinking water
  • Differences in geology, hydrology, geochemistry, and chemical use explain how and why aquifer vulnerability and concentrations of contaminants vary across the Nation
  • Changes to groundwater flow have also altered groundwater quality
  • Our actions today are determining groundwater quality for decades to come

Summary Report for the National Water-Quality Assessment Program Principal Aquifers Series, "The Quality of Our Nation's Waters—"

Circular 1360—Water Quality in Principal Aquifers of the United States, 1991–2010

Companion Reports

Circular 1337—Water Quality in the High Plains Aquifer, Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming, 1999–2004

Circular 1352—Water Quality in the Glacial Aquifer System, Northern United States, 1993–2009

Circular 1353—Water Quality in the Northern Atlantic Coastal Plain Surficial Aquifer System, Delaware, Maryland, New Jersey, New York, North Carolina, and Virginia, 1988–2009

Circular 1354—Water Quality in the Principal Aquifers of the Piedmont, Blue Ridge, and Valley and Ridge Regions, Eastern United States, 1993–2009

Circular 1355—Water Quality in the Upper Floridan Aquifer and Overlying Surficial Aquifers, Southeastern United States, 1993–2010

Circular 1356—Water Quality in the Mississippi Embayment–Texas Coastal Uplands Aquifer System and Mississippi River Valley Alluvial Aquifer, South-Central United States, 1994–2008

Circular 1357—Water Quality in the Denver Basin Aquifer System, Colorado, 2003–05

Circular 1358—Water Quality in Basin-Fill Aquifers of the Southwestern United States: Arizona, California, Colorado, Nevada, New Mexico, and Utah, 1993–2009

Circular 1359—Groundwater Quality in the Columbia Plateau and Snake River Plain Basin-Fill and Basaltic-Rock Aquifers and the Hawaiian Volcanic-Rock Aquifers, Washington, Idaho, and Hawaii, 1993–2005

First posted January 21, 2015

For additional information, contact:
Chief, National Water-Quality Assessment (NAWQA) Program 
U.S. Geological Survey
413 National Center
12201 Sunrise Valley Drive
Reston, VA 20192

Part or all of this report is presented in Portable Document Format (PDF). For best results viewing and printing PDF documents, it is recommended that you download the documents to your computer and open them with Adobe Reader. PDF documents opened from your browser may not display or print as intended. Download the latest version of Adobe Reader, free of charge. More information about viewing, downloading, and printing report files can be found here.

Suggested citation:

DeSimone, L.A., McMahon, P.B., and Rosen, M.R., 2014, The quality of our Nation’s waters—Water quality in Principal Aquifers of the United States, 1991–2010: U.S. Geological Survey Circular 1360, 151 p.,

ISSN 1067–084X (print)

ISSN 2330–5703 (online)


Chapter 1: Overview of Major Findings and Implications

Chapter 2: NAWQA Approach to Assessing Groundwater Quality

Chapter 3: Aquifers and Processes That Affect Groundwater Quality

Chapter 4: The Quality of Groundwater Resources For Drinking and Other Uses

Chapter 5: Understanding Where and Why Constituents From Geologic Sources Occur

Chapter 6: Understanding Where and Why Contaminants From Human Activities Occur

Chapter 7: How Does Our Use of Water Affect Groundwater Quality?

References Cited



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Page Last Modified: Wednesday, January 28, 2015, 08:27:24 AM