United States
Environmental Protection
Prevention, Pesticides
And Toxic Substances
May 10, 1993
4>EPA For Your Information
Running Title: 1992 Pesticides in Ground Water Database Report
The Office of Pesticide Programs (OPP) is responsible for protecting human and
environmental health from unreasonable risks due to pesticide exposure. Monitoring during the
last decade has shown that the nation's ground water is susceptible to contamination by
pesticides, particularly in areas with vulnerable aquifers and high pesticide use. Therefore, OPP
has taken a preventive approach to the protection of this valuable resource. Regulatory activities
have evolved to include, as a condition of registration or re-registration, a more rigorous
evaluation of a pesticide's potential to reach ground water.
The Pesticides in Ground Water Database (PGWDB) was created to provide a more
complete picture of ground water monitoring for pesticides in the U.S. The data in the PGWDB
has been assembled from numerous sources including state and federal agencies, chemical
companies, consulting firms, and private institutions that are investigating the potential for
ground water contamination by pesticides. It consists of computerized and hard copy raw data
and reports, and auxiliary information.
The 1992 Pesticides in Ground Water Database Report
The PGWDB Report is a summary and analysis of all of the data that OPP currently has
available, both computerized and in hard copy, concerning pesticides in ground water. The
report is presented as a National Summary and ten EPA regional volumes. The National
Summary provides background information and data collection procedures for the PGWDB,
summary results of the data collection effort, and a discussion of the data. The ten regional
volumes contain an introduction/explanation of the database and data from the individual states
in each region. Each regional volume contains state summaries that consist of a short overview
of pertinent regulations and the state's philosophy concerning ground water in general and
pesticides in particular. Following this is a summary of each study or monitoring effort sent to
Pesticides in Ground Water Database
A Compilation of Monitoring Projects: 1971-1991
August 1992

Data Interpretation and Uses
OPP uses this information source as an indication of the effectiveness of current
regulatory policies and as a tool to support and/or redirect the focus of regulatory activities when
necessary. The data collected has been used to support label advisories, requirements for
increased monitoring, re-registration, and special review. Combining the information in the
PGWDB with usage data will assist OPP in refining criteria used to identify pesticides, at an
early stage, that tend to leach to ground water. Additional uses for the data in the PGWDB
include identification of areas in need of further study, identification of the intensity of
monitoring for particular pesticides, and graphic display of ground water monitoring and/or
contamination by pesticides.
On a state or local level, the PGWDB provides access to data from neighboring states.
The PGWDB is also an environmental management tool for the states. Evidence that pesticide
residues occur in ground water can be used to target a state's resources for future monitoring
and to reassess pesticide management practices to prevent future degradation of ground-water
quality. In addition, the information presented in this report will be useful to state and regional
agencies when implementing two pollution-prevention measures being developed by EPA; the
Restricted Use Rule and the State Management Plans outlined in the Pesticides and Ground
Water Strategy.
Data Limitations
The PGWDB provides an overview of the ground-water monitoring efforts for pesticides
in the United States, the pesticides that are being found in the nation's ground water, and the
areas of the country that appear to be vulnerable to pesticide contamination. Despite their
apparent usefulness, these data do have limitations and must be used and interpreted carefully.
Differences in study design, laboratory procedures or equipment and sampling practices can
produce anomalies which make interpretation difficult when data are combined.
When viewed as a whole, it might appear the data gathered for this report are
representative of the United States and/or of general drinking water quality. This is not
necessarily the case. For example, many studies included sampling of aquifers that supply
drinking water, however these samples were usually taken at the well, not at the consumer's tap.
Therefore, conclusions concerning finished water can only be drawn by careful examination of
the data on a study by study basis. In addition, ground-water monitoring programs vary widely
in sampling intensity and design from state to state. Not surprisingly, the states that sampled
the greatest number of wells were often those that found the greatest number of contaminated
wells. This should not be misconstrued to mean that the ground water in these states is more
contaminated than that of other states, or that all ground water in these states is contaminated.
On the contrary, an active, supported sampling program generally indicates a high regard for
ground-water quality.

Summary Results from the 1992 Pesticides in Ground Water Data Base Report
68,824 Total wells
65,865 Total drinking water wells
16,606 Total wells
9,911 Wells with detections ^ EPA drinking water standards
15,502 Total drinking water wells
9,509 Drinking water wells with detections ^ EPA drinking water standards
13,731 Wells with detections due to Normal Field Use
205 Wells with detections due to Point Source (well contamination due to spills etc.)
2,672 Wells with detections from Unknown Sources
302 Pesticide related compounds
258 Parent compounds (the original registered pesticide)
45 Degradate compounds (breakdown products of the original pesticide)
132 Total compounds detected
27 Compounds are designated as Restricted Use
34 Compounds are are no longer registered for use in the United States
37 Compounds detected at levels ^ EPA drinking water standards
117 Parent compounds detected
34 Parent compounds detected at levels ^ EPA drinking water standards
16 Degradate compounds detected
3 Degradate compounds detected at levels > EPA drinking water standards
45 States submitted monitoring studies
8 States sampled 1,000 or more wells	~
3 States sampled 10,000 or more wells
42 States had one or more wells with pesticide detections
19 States had greater than 100 wells with pesticide detections
3 States had greater than 1,000 wells with pesticide detections

Availability of the PGWDB and 1992 PGWDB Report
The PGWDB, including project summaries, well descriptions and sampling results, will
be added to the Pesticide Information Network (PIN). The PIN is OPP's interactive, online
database containing up-to-date pesticide information. To obtain more information concerning
the PIN and the timetable for adding the PGWDB contact PIN User Support at 703-305-7499.
Copies of the Pesticides In Ground Water Database; A Compilation of Monitoring
Studies: 1971 - 1991; National Summary, may be purchased from:
Superintendent of Documents
U.S. Government Printing Office
Washington DC 20402
Phone: 202-783-3238
Order Number: 055-000-00413-7	Price: $13:00
The National Summary volume, along with each of the regional volumes, may also be
purchased from NTIS. They are available in both paper copy (pc) and microfiche (mf). Please
specify the format when ordering. Contact:
Order Desk
National Technical Information Center (NTIS)
5285 Port Royal Road
Springfield, VA 22161
Phone: 703-487-4650 or 800-557-NTIS
NTIS Order Number
Pric# (PC)
Price (mf)
National Summary
$ 36.50
$ 17.50
Region 1
Region 2
Region 3
Region 4
Region 5
Region 6
Region 7
Region 8
Region 9
Region 10