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EXPLANATION

Ground-water study

Surface-water study

Figure 1.  Location of Source Water-Quality Assessments, 2002–07. Additional studies are planned to be

completed through 2013.

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2007–3069

August 2007

National Water-Quality Assessment Program—

Source Water-Quality Assessments

Printed on recycled paper

In 2002, the National 

Water-Quality Assessment 

(NAWQA) Program of the 

U.S. Geological Survey 

(USGS) implemented Source 

Water-Quality Assessments 

(SWQAs) to characterize 

the quality of selected rivers 

and aquifers used as a source 

of supply to community 

water systems in the United 

States. These assessments 

are intended to complement 

drinking-water monitoring 

required by Federal, State, 

and local programs, which 

focus primarily on posttreatment compliance 

monitoring.

Purpose

The primary objective of SWQAs 

is to determine the occurrence of about 

280 primarily unregulated anthropogenic 

organic compounds in source water used 

by community water systems. Source 

water is the raw (ambient) water collected 

at a supply well or surface-water intake 

prior to water treatment used to produce 

finished water. A secondary objective 

is to understand occurrence patterns 

in source water and determine if these 

patterns also occur in finished water prior 

to distribution.

The NAWQA Program is planning 

as many as 30 surface-water and 

30 ground-water assessments through 

2013 (fig. 1). The findings are not 

intended to comprehensively portray 

the quality of our Nation’s source 

waters owing to the relatively small 

number of water supplies studied. They 

are, however, intended to improve 

understanding of ambient resource 

conditions in a drinking-water-supply 

context.

Approach

Monthly samples of source water 

and finished water are collected in 

each of the surface-water assessments 

to characterize seasonal variability. 

Additional samples are collected during 

hydrologic events or other critical times 

when water-quality conditions may 

change quickly and (or) when large 

concentrations are most likely to occur. 

Samples from 15 high-production wells 

supplying community water systems 

and the associated finished water are 

collected in each of the ground-water 

assessments. Specific information on 

assessment design and analytical methods 

are available in Carter and others (2007).
Communications

USGS findings can be presented at briefings, in reports and journal articles, and 

at scientific conferences, and can be reported on a local and national basis. Sampling 

locations of river intakes and supply wells are not disclosed in reports to meet USGS 

policy and source-water security purposes under the U.S. Government’s Homeland 

Security activities. Participating community water systems, however, do receive 

USGS results, may use and distribute the data as they choose, and are encouraged to 

serve as coauthors of publications as appropriate.

Much of the data obtained through these efforts are not directly comparable to 

data used in Consumer Confidence Reports (CCRs) (http://www.epa.gov/safewater/

ccr/index.html), which are communicated to the public by water utilities. The lack 

of comparability relates to differences in sampling objectives, design, and analytical 

methodologies, including (1) samples from USGS assessments are collected 

from both source water and finished water; (2) many of the compounds analyzed 

are unregulated and not monitored by community water systems; and (3) USGS 

laboratory reporting levels generally are considerably lower than those used in CCRs 

and for compliance monitoring customarily reported to State and Federal drinkingwater agencies.

For more information, contact:

Gregory C. Delzer

U.S. Geological Survey

1608 Mt. View Road

Rapid City, SD 57702

605-394-3230

gcdelzer@usgs.gov

Information regarding the National 

Water-Quality Assessment Program is 

available at http://water.usgs.gov/

nawqa/.

By Gregory C. Delzer and Pixie A. 

Hamilton

Prepared by the USGS Publishing Network, 

Helena Publishing Service Center

ANTHROPOGENIC ORGANIC COMPOUNDS

Anthropogenic organic compounds are man-made or man-caused chemicals 

that contain carbon and other elements and have various uses. The primary use or 

source groups for the approximately 280 compounds analyzed in water samples 

for SWQAs are:

Disinfection by-products

Fumigant-related compounds

Fungicides

Gasoline hydrocarbons, oxygenates, and oxygenate degradates

Herbicides and herbicide degradates

Insecticides and insecticide degradates

Manufacturing additives

Organic synthesis compounds

Pavement- and combustion-derived compounds

Personal-care and domestic-use products

Plant- or animal-derived biochemicals

Refrigerants and propellants

Solvents

Additional information about the primary use or source groups and a list 

of the compounds analyzed in water samples are available in Carter and others 

(2007).

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ROLE OF SWQAs

Collaboration with and complementing work of other Federal, State, 

and local organizations are important components of SWQAs. Unique 

characteristics of these assessments, which provide additional information and 

understanding to other monitoring activities, include:

Data on a diverse suite of organic compounds with potential humanhealth concerns that are not commonly measured in compliance or 

regulatory programs

The ability to expand the list of compounds monitored to include 

additional emerging contaminants as analytical methods are approved by 

USGS

Low-level analytical methods to gain a more complete understanding of 

contaminant occurrence in source water and finished water

A common sampling approach and laboratory to minimize sample 

contamination and reduce analytical variability.

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Reference

Carter, J.M., Delzer, G.C., Kingsbury, J.A., 

and Hopple, J.A., 2007, Concentration 

data for anthropogenic organic 

compounds in ground water, surface 

water, and finished water of selected 

community water systems in the United 

States, 2002–05: U.S. Geological Survey 

Data Series 268, accessed July 30, 2007, 

at http://pubs.usgs.gov/ds/2007/268/.