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Scientific Investigations Map 2931

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The Occurrence of Volatile Organic Compounds in Aquifers of the United States

By Wayne W. Lapham, Janet M. Carter, John S. Zogorski, and Joshua F. Valder

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Study Basics

The U.S. Geological Survey’s National Water-Quality Assessment (NAWQA) Program recently completed a national assessment of volatile organic compounds (VOCs) in ground water (Zogorski and others, 2006). As part of this assessment, samples of ambient ground water collected from 3,498 wells during 1985–2002 were selected for characterizing the occurrence of 55 VOCs in 98 aquifer studies. The 55 VOCs were assigned to the following groups on the basis of their primary usage (or origin): (1) fumigants, (2) gasoline hydrocarbons, (3) gasoline oxygenates, (4) organic synthesis compounds, (5) refrigerants, (6) solvents, and (7) trihalo-methanes (chlorination by-products).

The samples were collected throughout the conterminous United States as well as Alaska and Hawaii. The sampled wells had a variety of uses including domestic supply (61 percent), public supply (15 percent), monitoring (10 percent), other (13 percent), and unknown (1 percent).

NAWQA aquifer studies are large-scale resource assessments of ground water that provide a general characterization of water-quality conditions in locally and regionally important aquifers or portions thereof. In general, the aquifers (or portions thereof) selected for study were some of the most intensively used aquifers for drinking water in greaterHawaiiOahuAlaskathe Nation. The 98 aquifer studies collectively provide an important national perspective on the current (19852002) extent of VOC contamination and regional patterns of VOC occurrence in ground water. More information about this national assessment of VOCs is available at a supporting Web site (

For more information about USGS activities in South Dakota, visit the USGS South Dakota Water Science Center home page.

For more information about USGS National Water-Quality Assessment Program, visit the NAWQA Program home page or for more information about the USGS National Water-Quality Assessment Program Volatile Organic Compound National Syntheses, visit the VOC National Synthesis home page.

Please send questions and comments about this map to:
Chief, VOC National Synthesis
U.S. Geological Survey
1608 Mt. View Road
Rapid City, South Dakota 57702
Telephone: 605-394-3214
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