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Circular 1357

National Water-Quality Assessment Program

The Quality of Our Nation’s Waters

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

By Nancy J. Bauch, MaryLynn Musgrove, Barbara J. Mahler, and Suzanne S. Paschke

Thumbnail of and link to report PDF (15.4 MB)Overview

Availability and sustainability of groundwater in the Denver Basin aquifer system depend on water quantity and water quality. The Denver Basin aquifer system underlies about 7,000 square miles of the Great Plains in eastern Colorado and is the primary or sole source of water for domestic and public supply in many areas of the basin. Use of groundwater from the Denver Basin sandstone aquifers has been instrumental for development of the south Denver metropolitan area and other areas, but has resulted in a decline in water levels in some parts of the system. Human activities in many areas have adversely affected the quality of water in the aquifer system, especially the shallow parts. Groundwater in deeper parts of the system used for drinking water, once considered isolated from the effects of overlying land use, is increasingly vulnerable to contamination from human activities and geologic materials. Availability and sustainability of high-quality groundwater are vital to the economic health of the Denver Basin area.

Major Findings

  • The quality of groundwater used for drinking water generally is very good
  • Most constituents at a concentration of concern for human health were from geologic sources
  • Nitrate concentrations in shallow groundwater were low despite widespread fertilizer use
  • Irrigation of agricultural and urban lands has adversely affected the quality of shallow groundwater
  • High-volume pumping of groundwater can increase the vulnerability of the Denver Basin bedrock aquifers to contamination

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:

Bauch, N.J., Musgrove, MaryLynn, Mahler, B.J., and Paschke, S.S., 2014, The quality of our Nation’s waters—Water quality in the Denver Basin aquifer system, Colorado, 2003–05: U.S. Geological Survey Circular 1357, 100 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: Environmental Setting and Water-Resource Characteristics

Chapter 4: Natural and Human Factors that Affect Groundwater Flow and Quality

Chapter 5: Quality of Groundwater Used for Drinking and Irrigation

Chapter 6: Understanding Where and Why Key Contaminants Occur in Groundwater

Chapter 7: Vulnerability of Groundwater to Contamination

References Cited



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