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Circular 1358

National Water-Quality Assessment Program

The Quality of Our Nation’s Waters

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

By Susan A. Thiros, Angela P. Paul, Laura M. Bexfield, and David W. Anning

Thumbnail of and link to report PDF (93.98 MB)Overview

The Southwest Principal Aquifers consist of many basin-fill aquifers in California, Nevada, Utah, Arizona, New Mexico, and Colorado. Demands for irrigation and drinking water have substantially increased groundwater withdrawals and irrigation return flow to some of these aquifers. These changes have increased the movement of contaminants from geologic and human sources to depths used to supply drinking water in several basin-fill aquifers in the Southwest.

Major Findings

  • Contaminants in water from one of every three drinking-water wells sampled are a potential human-health concern
  • Arsenic and uranium derived from geologic sources are potential drinking-water concerns
  • Dissolved-solids concentrations in groundwater are increasing in some areas
  • Artificial recharge and groundwater withdrawals are moving contaminants to deeper parts of basin-fill aquifers

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

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Suggested citation:

Thiros, S.A., Paul, A.P., Bexfield, L.M., and Anning, D.W., 2014, The quality of our Nation's waters—Water quality in basin-fill aquifers of the southwestern United States: Arizona, California, Colorado, Nevada, New Mexico, and Utah, 1993–2009: U.S. Geological Survey Circular 1358, 113 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: Background: Environmental Setting, Hydrogeology, Population, Land Use, and Water Use

Chapter 4: The Hydrology of Southwest Basin-Fill Aquifers and How Human Alterations Affect Groundwater Quality

Chapter 5: Quality of Groundwater Used for Drinking and Irrigation

Chapter 6: Understanding Where and Why Contaminants Occur in Southwest Basin-Fill Aquifers

References Cited



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