United States
Environmental Protection
Agency
Prevention
Pesticides and
Toxic Substances
(H7507C)
EPA 734-12-92-001
August 1992
&EPA Pesticides In Ground Water Database
A Compilation Of Monitoring Studies: 1971-1991
Region 8
-
1C
4
COLORADO
SOUTH DAKOTA
MONTANA
UTAH
NORTH DAKOTA
WYOMING
: on Recycled Paper
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Pesticides in Ground Water Database-1992 Report
Mention of trade names, products, or services does
not convey, and should not be interpreted as
conveying, official EPA approval, endorsement, or
recommedation.
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Pesticides in Ground Water Database -1992 Report
Pesticides in Ground Water Database
A Compilation of Monitoring Studies: 1971 -1991
Region 8
Office of Pesticide Programs
Environmental Fate and Effects Division
Environmental Fate and Ground Water Branch
Henry Jacoby, Chief
Pesticide Monitoring Program Section
Constance Hoheisel
Joan Kanie Susan Lees
Leslie Davies-Hilliard Patrick Hannon
Roy Bingham
Ground Water Technology Section
Elizabeth Behl
David Wells EsteUaWaldman
August 1992
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Pesticides in Ground Water Database - 1992 Report, Region 8
CONTENTS
OVERVIEW OV-1
REGIONALMAP OV-14
GRAPH: WELLS BY STATE OV-15
STATE SUMMARIES:
COLORADO
State Map 1-CO-l
Overview of State Legislative and Environmental Policies
Regarding Pesticides in Ground Water l-CO-3
Reported Studies of Pesticides in Ground Water l-CO-3
Table: Pesticide Sampling in the State of Colorado l-CO-5
Table: State of Colorado - Wells by County l-CO-5
MONTANA
State Map 1-MT-l
Overview of State' Legislative and Environmental Policies
Regarding Pesticides in Ground Water l-MT-3
Reported Studies of Pesticides in Ground Water l-MT-3
Table: Pesticide Sampling in the State of Montana l-MT-5
Table: State of Montana - Wells by County l-MT-25
NORTH DAKOTA
State Map 1-ND-l
Overview of State Legislative and Environmental Policies
Regarding Pesticides in Ground Water l-ND-3
Reported Studies of Pesticides in Ground Water l-ND-3
Table: Pesticide Sampling in the State of North Dakota l-ND-7
Table: State of North Dakota - Wells by County l-ND-17
SOUTH DAKOTA
State Map 1-SD-l
Overview of State Legislative and Environmental Policies
Regarding Pesticides in Ground Water l-SD-3
Reported Studies of Pesticides in Ground Water l-SD-3
Table: Pesticide Sampling in the State of South Dakota 1-SD-ll
Table: State of South Dakota - Wells by County .- l-SD-19
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Pesticides in Ground Water Database -1992 Report. Region 8
CONTENTS
WYOMING
State Map IrWY-l
Overview of State Legislative and Environmental Policies
Regarding Pesticides in Ground Water .- l-WY-3
Reported Studies of Pesticides in Ground Water l-WY-3
Table: Pesticide Sampling in the State of Wyoming l-WY-5
Table: State of Wyoming - Wells by County 1-WY-ll
APPENDICES
Pesticide Cross-Reference Table Appendix M
National Survey of Pesticides in Drinking Water Wells Appendix H-l
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L INTRODUCTION
The U.S. Environmental Protection Agency/Office of Pesticide Programs (EPA/OPP)
is responsible for protecting human and environmental health from unreasonable risk due
to pesticide exposure. Monitoring efforts carried out during the last decade have shown mat
the nation's ground water can become contaminated with pestiddes, particularly in areas
with high pesticide use and vulnerable aquifers. Therefore, OPP has taken a strong
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. OPP has also formed strong
partnerships with other federal and state agencies responsible for various aspects of ground-
water protection.
The Pesticides in Ground Water Database (PGWDB) was created to provide a more
complete picture of ground-water monitoring for pesticides in the United States. It is a
collection of ground-water monitoring studies conducted by federal, state and local
governments, the pesticide industry and private institutions. It consists of monitoring data
and auxiliary information in both computerized and hard-copy form. This report, Pesticides
in Ground Water Database - A Compilation of Monitoring Studies: 1971 -1991, was prepared
to summarize and share the results of the studies in the PGWDB. It consists of 11 volumes:
a National Summary and ten EPA regional summaries. Each volume provides a detailed
description of the computerized PGWDB and a guide to reading and interpreting the data.
The data are presented as maps, graphs and tables.
These data are extremely valuable, but must be interpreted carefully.: In general, 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.
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.
OV-1
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The database and this report are the result of the efforts of a great many individuals,
among whom are the state officials and principal investigators who gave
generously of their time to provide OFF with information concerning their work. In
publishing this report, OFF intends not only to provide data, but also to identity points of
contact, in order to share expertise among those responsible for the protection of the
nation's ground-water resources.
To make this information available to as many decision makers in state and other
federal agencies as possible, the computerized portion of the PGWDB wfll become a part
of the Pesticide Information Network (PIN).1 The FIN is a computerized collection of files
that contain pesticide monitoring and regulatory information. The PIN functions much like
a PC-PC bulletin board andean be accessed by anyone with a computer and a modem. The
PIN is currently undergoing an expansion that wfll allow new types of information to be
included and increase the number of simultaneous users. The new FIN wfll be available in
1993 and will contain the PGWDB, environmental fate chemical/physical parameters for
pesticides, pesticide regulatory information (Restricted Use, Special Review, canceled and
suspended) and a certification and training bibliography.
H. THE ROLE OF PESTICIDE MONITORING
The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) requires EPA to
monitor the environment for pesticide residues [section 20, parts (b) and (c)]. The primary
goal of pesticide monitoring is to improve the soundness of FIFRA risk/benefit regulatory
decisions by providing information on the concentrations of pesticide residues and the
effects that exposure to these residues have on human health and the environment In
addition, long-term changes in environmental quality can be detected through the analysis
of monitoring data. OPP can use this information to measure the effectiveness of regulatory
decisions and to indicate potential environmental problems.
EPA has directly sponsored some large-scale pesticide monitoring projects, such as the
National Monitoring Programs of the 1970s2 and the recent National Survey of Pesticides
in Drinking Water Wells. This type of monitoring is intended to provide information on
a national level involving large numbers of pesticides. It does not provide information
concerning localized problems or long-term trends. This method of data gathering is also
extremely resource-intensive. An alternative approach for OPP is to support and gather
information from monitoring studies performed by others. Since the responsibility for
protecting the nation's ground water is shared by federal and state governments, OPFs data-
handling responsibilities not only include procuring the most current information for its own
needs, but also sharing this information with its partners hi state and federal agencies. The
development of the Pesticides in Ground Water Database is a step in this direction.
OV-2
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ffl. BACKGROUND
OPP began collecting ground-water studies for the PGWDB in the early 1980s. In 1988,
an effort was made to review and catalog these data. Summary results of this effort were
computerized and then published in the Pesticides in Ground Water Database: 1988 Interim
Report.4
Since the 1988 Interim Report was issued, many things have changed. State-sponsored
projects, initiated in the late 1980s, have been completed and digitized, monitoring
methodologies and computer technology have improved, and the quality and quantity pf data
have increased. Based on extensive use of the 1988 database by OPFs Ground Water
Technology Section and the comments received from other users, both within and outside
of OPP, the computerized database and the hard-copy report were restructured. The new
computerized structure is more appropriate for the quality and quantity of the information
currently available, as well as for that expected in the future. The new structure is both well
and sample specific; that is, it contains description and location information for each well
sampled and the results of each analysis. This structure allows ground-water monitoring
data to be sorted in a variety of ways, such as by well depth, well location, and sampling
date. The new report structure provides national, regional, state and county summaries so
that readers can select the resolution appropriate for their needs.
Most of the data in the PGWDB have been produced directly by state agencies or by
private institutions that are sponsored by federal or state agencies. Some pesticide industry-
sponsored studies have also been included in the PGWDB. These studies were conducted
to support the registration status of a particular pesticide and were generally conducted in
areas that are vulnerable to ground-water contamination by pesticides.
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associated with specific study summaries or reports sent to OFF by state agencies. These
state agencies provided their agency code, station codes, parameter codes, sampling dates
and other pertinent information so that the correct data could be extracted from STORET.
Data from the National Survey of Pesticides in Drinking Water Wells (NPS)S have not
been included in PGWDB, since these data have been recently and extensively presented
elsewhere. We are currently working on electronically transferring the results of the NFS
pesticide analyses so they will be available when the PGWDB becomes part of the PIN.
IV. THE COMPUTERIZED DATABASE
The computerized database consists of three files related to each other by study
identification and unique well number. The first file contains information describing the
study, the second contains information describing each well and the third contains sample
information. Data elements stored in these files are presented in Figure 1. These data
elements are based on EPA's recommended minimum set of data elements for ground-water
monitoring published in Definitions for the Minimum Set of Data Elements for Ground-Water
Quality, Jufy 22,1990.*
FIGURE 1. Data Elements for the Pesticides in Ground Water Database
Sponsoring Agency(ies)
State and County F1PS Codes'
Pesticide'
Project Officer(s)
Latitude and Longitude*
Concentration (ug/l)
PO Address(es)
Depth to Meter Table (•)
Unit of Detection (ug/l)
PO Telephoned)
Met I Depth (•>
Saapl« date
USEPA Region
Depth to Top end Botton of Screen
Interval <•)
Analytical Method8
Starting and .Ending Dates
Hell Type4
Origin of Contaaination9
Publication Date
Uetl Log t Other Information3
Abstract
Altitude"
1. This is a unique identifier assigned to each well in the well file. Many states have assigned a unique
identifier to wells sampled In these cases, the number was retained, and used in the PGWDB as that weir's
unique well number.
1 The Federal Information Processing Standard (PIPS) alphabetic or numeric codes for states (example MI
is the alphabetic code for Michigan, 26 in the numeric code for Michigan). County codes are three digit
numeric codes.
OV-4
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representations tK«t jnftfan*- • locatKm on the surface of die earth using the equator (latitude)
and the Prime Meridian (longitude) as origin. Coordinates are measured in degrees, minutes, and seconds
with an indicator of north or south, and east or west
4. Wells have been classified as follows:
Drinking water public community - a system of piped oVmlting water that either nas at least 15 service
> or serves at least 25 permanent:
Drinking water pubSc non-community - weDs serving publk facilities such as fire stations, schools, or
•. libraries.
Drinking water private - privately owned wellsserving a residence or farm.
Non-drinking water monitoring - weDs installed specifically for monitoring ground water.
Non-drinking water other • weDs used for rogation, industrial application, etc.
S. This field wfll allow storage of limited well log or other information about the weO, such as construction
details.
6. The vertical distance from the National Reference Datum to the land surface or other measuring point in
meters.
7. Pesticides are tracked by their Chemical Abstracts System (CAS) number. There is also a cross-reference
file that contains all pesticide synonyms and other OPP reference numbers. Any chemical that is currently
or has ever been registered as a pesticide by the USEPA, Office of Pesticide Programs is eligible to be
included in the PGWDB. Some chemicals might be more commonly associated with industrial processes;
however, if these chemicals are now or were previously registered and used as pesticides, monitoring results
will be included in the database,
8. A short name, reference or description of the analytical method which was used. This field is not intended
to hold the entire method.
9. An origin of contamination is listed for each analysis performed as follows:
NFU - Known or suspected normal field use
PS • Known or suspected point source
UNK - Unknown source of contamination
These files will be available through the PIN in 1993. The data management software
for this system is ORACLE running under UNIX. However, OPP will accept and translate
data created in nearly any format, operating system or medium. To access the PIN, contact
User Support at 703-305-7499.
V. THE 1992 PESTICIDES IN GROUND WATER DATABASE REPORT
The 1992 PGWDB report is a summary and presentation of all the data OPP currently
has available, both in computerized and in hard-copy form, concerning pesticides in ground
water. The report is organized as a National Summary and ten EPA regional summaries.
Each volume provides background information on pesticide monitoring, a description of the
computerized portion of the database and a guide to reading and interpreting the data
presented in the report.
OV-5
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The National Summary contains summaiy results of the data collection effort for all-
states and a discussion of the data. The regional volumes contain data from the individual
states in each EPA Region. Each regional volume contains state summaries, which consist
of: 1) a short overview of the state's philosophy and pertinent regulations concerning
ground-water quality and pesticides, 2) a summary of each study or monitoring effort sent
to OPP, and 3) summary data for each state presented in tables, graphs and maps. In
essence, the study summaries were written by the principal investigators of each study.
Whenever possible, the author's abstracts, summaries and conclusions were reproduced
verbatim, so that the tone and intent of their work would not be misinterpreted.
There are two appendices in each volume of die report Appendix I contains a
Pesticide Cross Reference Table, which provides pesticide names, synonyms and the
regulatory status and lifetime Health Advisory (HA) Level or Maximum Contaminant Level
(MCL)7 for each pesticide. Appendix n provides a brief overview and reference information
for the NFS.
Summary and Presentation of Groupd-Wqter Monitoring Data:
The data in this report are presented in three different formats: maps, graphs and
tables. Their format and content are explained below. Each format is displayed at four
different resolution levels: national, regional, state and county. The charts and maps were
intended to provide an "at-a-glance" visual summaiy of the information collected for the area
in question. The tables provide detailed information concerning sampling dates, numbers
of wells sampled, samples analyzed, concentration ranges, and the relationship between
pesticide concentrations and current EPA drinking water standards.
1. Maps
The maps presented in this report display the number of wells sampled and the number
of wells with pesticide detections. Map legends are consistent throughout the report to
assist in any visual comparison of the maps. A regional-scale map illustrating the
frequency of pesticide detections as a function of the total number of wells sampled is
presented at the beginning of each EPA regional volume. The regional maps, display
information for each state in that EPA region. All of the regional maps are included
in the National Summary. In addition, a state- scale map, in which the data are
presented at the county level, is included with each state summary. State maps are also
annotated with a list of pesticides detected in that state.
2. Graphs
Bar graphs, for each state within a region, illustrate the number of wells sampled, the
number of wells with pesticide detections, and the number of wells with pesticide
detections exceeding the MCL or lifetime HA. The graphs present this information
ranked in descending order by the number of wells with pesticide detections. The
version of this graph in the National Summary displays this information for each state.
A similar graph in each EPA regional volume presents data only for the states in that
region. The National Summary contains an additional graph, illustrating the above
information by pesticide. Pesticides for which analyses were performed but were not
detected in any wells are listed alphabetically at the end.
OV-6
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3. Tables
Two basic data tables are used throughout this report to summarize ground-water
monitoring information: the "Pesticides" table and the "Wells" table. Figures 2 and 3
provide a detailed explanation of the information contained in each column for the two
standard tables. The numbers that occur in the field descriptors correspond to the
definitions listed below the example table.
The "Pesticides" table is illustrated in Figure 1 In this table, information is organized
by pesticide. The monitoring locations, sampling frequencies, number of wells
monitored, sampling results and concentration ranges are provided. In the National
Summary, this table details the monitoring location to the state level and also includes
the regulatory status for each pesticide. In the regional volumes, monitoring location
is provided to the county level for each state and the table is expanded to include
monitoring data for samples taken from each well
FIGURE! Pesticides Table
PESTICIDE SAMPLING IN THE STATE OF
TOTAL DISCRETE
WELLS OR SAMPLES
TOTAL DISCRETE
UELLS/SAMPLES
GRAND TOTAL
DISCRETE
UELLS/SAMPLES
I The tables are arranged in alphabetical order by the parent pesticide common name. -Degradates of parent •
pesticides are listed directly following the parent. Any chemical that is currently or has ever been registered as
a pesticide by the USEPA Office of Pesticide Programs is eligible to be included in these tables. Some chemicals
included in these tables are more commonly associated with industrial processes; however, these chemicals were
at some time also registered as pesticides.
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2 County names are fisted in alphabetical order for each pesticide that ww monitored.
1 Well sampfing dates are given by year and month(s). Months separated by a comma (1,3) means that samples
were taken in these months only. Months separated by a dash (1-5) is die range of months m which sampling
red, samples were taken in aQ months within the range.
The total number of weSs that were sampled at least once during the time period stated m the previous
£ WeOs with pesticide detections within the time period given m the date column (3). Wells with positive
analytical results were classified based upon whether the results were above or below the MCL. If a pesticide
did iiot hare an established MCX the EfetmeH^ If neither
of these values were established, the well was classified as less than the MCL WeDs were classified based upon
their highest analytical result Therefo^
Any Well With at least
one positive analysis but aO analyses less than the MCL or HA was classified as < MCL
& The total number of .sjUBBlss analyzed for that pesticide within the tone period recorded in the date column.
2 Sampteswith pesticide detections were counted based upon whether the results were above or below the MCL
or lifetime HA as stated in 5 above.
£ The range of positive results in ug/L (ppb) for the tune period specified m the date column.
2 The total number of discrete weds that were sampled at least once and analyzed for the pesticide listed in
column L 'See Note
Iffi The total number of discrete wells m which the pesticide was detected based upon whether the results were
above or below the MCL Wells were classified as explained in 5 ahnvr., based npnn fhp highest flMtyrical ffCT't
11 Total number of samples analyzed for a particular pesticide.
12 The total number of samples in which the pesticide was detected that are £ MCL or < MCL as explained
in 5 above.
12 The grand total of discrete weQs sampled in the state for any pesticide. * See Note
14 The grand total of discrete wells with at least one detection of any pesticide. Wefls are classified above or
below MCL or HA as explained in 5 above. *See Note
15 Grand total of samples taken in the state. 'See Note
US The grand total of samples with any pesticide detection for the state. Samples were classified as > or < the
MCL based upon their highest analytical result as explained in 5 above. 'See Note
*Notc: Some wells were sampled more than once, (Le., during several successive years) and some weDs were
sampled for more than one pesticide. Therefore, the total number of discrete wells is not necessarily the
arithmetic sum of the wefls listed Similarly some samples were analyzed for more than one pesticide, therefore,
the total number of discrete samples for the state will not be, in all cases, the arithmetic sum for the cohann.
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Figure 3 illustrates the "Wells" table. In this table, ground-water monitoring information
is organized by wen type, or use, and source of contamination. In the National
Summary, the information is summarized by state. In the regional volumes, the
information is summarized by county for each state in the region.
FIGURE 3. Wells Table
STATE OF
1EUS IT COURT
_2. Drinking Water wells include community (municipal), public non-community, and private wells. Public non-
community wells are those that exclusively serve public buildings such as fire stations, schools, or libraries.
2 Monitoring wells, installed solely to monitor ground water for contaminants.
2 Other wells include: irrigation wells, stock watering wells, springs, and tile drams.
4 Total number of each type of well sampled in each county.
j> The number of wells per county in which a pesticide was detected. Wells were classified based upon whether
the results were above or below an MCL for any of the pesticides detected. If a pesticide did not have an
established MCL, the lifetime HA level was used. If neither of these values were applicable, the well was
classified as less than the MCL and it was so noted at the end of the table. Wells were classified based upon
their highest analytical result Therefore, any well-with at least one positive analysis greater than or equal to the
MCL or HA was classified as > MCL. Any well with at least one positive analysis but all analyses less than the
MCL or HA was classified as < MCL.
Contaminated wells were placed in one of the following categories based on the opinion of the study director
it NFU=Known or Suspected Normal Field Use.
2 PS = Known or Suspected Point Source.
S. UNK=Unknown source of contamination. Wells were categorized as "unknown" if the study director did not
know the source of contamination, or if there was no information available concerning the source of
contamination.
5 Total number of wells in each category.
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VL DATA INTERPRETATION
Ground-water monitoring data in this report have 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. These data are extremely valuable, but must be interpreted carefully. In general,
the PGWDB provides a relatively comprehensive 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 the most vulnerable to
pesticide contamination.
Nationally, part of OFFs regulatory mission is to prevent contamination of ground-
water resources resulting from the normal use of registered pesticides}' OFF routinely
reassesses the impact that registered pesticides have on the quality of ground-water
resources. Hie PGWDB will be used to support ongoing regulatory activities, such as
ground-water label advisories, monitoring studies required for pesticide re-registration and
special review activities. In addition, combining the information in the PGWDB with other
environmental fate data and usage data will assist .OFF, at an early stage in the regulatory
process, in refining criteria used to identify pesticides that tend to leach to ground water.
On a state or local level, the PGWDB can be used as a reference so that a state may
access data from neighboring states. Evidence that pesticide residues occur in ground water
can be used to target a state's resources for future monitoring and to re-assess pesticide
management practices to prevent future degradation of ground-water quality. The
information presented in this report will also 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. 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 activities and localization of pesticide
contamination.
VH. DATA LIMITATIONS
Despite their apparent value, these data do have limitations and must be used and
interpreted carefully. Differences in study design, laboratory procedures/equipment,
sampling practices, or well use can affect results. Some of the limitations governing the
interpretation of the data in the PGWDB are discussed below:
1) The PGWDB is not a complete data set of all ground-water monitoring for
pesticides in the United States. While we have attempted to include as many
sources as possible, other data exist of which we are not aware OF to which we do
not yet have access.
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2) Monitoring for pesticides in ground water has not been performed in a uniform
manner throughout the United States, Some states have extensive monitoring
programs for pesticide residues, while others have more limited monitoring
programs. In general, more extensive ground-water monitoring programs tend to
be found in the states where pesticide use is heavy. This creates a picture that does
not necessarily represent the overall impact of pesticides on ground-water quality
nationwide.
3) Differences in ground-water monitoring study design can radically affect the results.
Many monitoring efforts were initiated in response to suspected problems, and
therefore yielded a disproportionately high number of positive samples. These
results cannot be extrapolated to represent a larger region or state. Other efforts
sampled a small number of wells or sampled under conditions in which
contamination was unlikely. Still others were statistically designed studies, intended
to be extrapolated to a specific population of wells. Each of these scenarios
presents a vastly different view of the condition of the ground-water resource
sampled.
4) Analytical methods and limits of detection have changed over time, and also vary
from laboratoiy to laboratory. Therefore, comparisons between the results of
different studies and across several years must be performed carefully to avoid
errors in interpretation.
- 5) Differences in construction, depth, location and intended use can greatly affect the
likelihood that a particular well will become contaminated by pesticides. Some of
these issues were addressed in the individual study summaries when such details
were available. However, this information was not always provided and tends to
be obscured when large amounts of data are summarized. Tlie reader is cautioned
to read the study summaries carefully and interpret the resulting data summaries
conservatively.
Vffl. THE FUTURE
The vulnerability of ground water to contamination by pesticides depends upon a variety
of factors including depth, topography, soil, climate, pesticide use and pesticide application
practices. In some cases, ground water is shallow or closely connected with surface water
and the results of surface activities can be observed within months. More often,
contamination is not observed for many years, allowing cause-and-effect relationships to
become obscured. This report, for the most part, is a retrospective examination of the
agricultural practices of the 1960s and 1970s, the results of which were observed through
monitoring performed 20 years later. The condition of our ground-water resources for the
next 20 years will be greatly affected by how we are handling our chemicals now. Our
challenge today is clearly prospective.
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EPA's Office of Pesticide Programs (OPP) is planning to publish a summary report of
the data in the PGWDB on approximately a yearly basis. We are interested in presenting
the data in a manner that is the most helpful to as many users as possible. The following
are areas in which we would like to receive comments:
1. Should future reports summarize only "new data" (those received since the last
report) or an of the data? Should we continue to report very old monitoring data
(10 to 20 years), given the fact that some of these studies had very high detection
limits and monitored for pesticides that are no longer of regulatory interest?
2. What changes should be made to the maps, graphs and tables? Are they too
detailed or not detailed enough? Are important pieces of information missing? Is
there a clearer or more useful way to present these data?
3. How are those outside of OPP using the PGWDB?
We appreciate all of those who took the time to comment on the draft version of this
report Many of the suggestions offered were included in this final version. However, some
very good suggestions regarding changes to the tables could not be included in this report
due to time constraints. These suggestions were taken seriously and will be considered for
future reports.
For the PGWDB to retain its value, OPP must continue to gather and share as much
pesticide monitoring information as possible. Any government agency or private institution
that would like to have its work included in the PGWDB should provide a hard copy of a
final or interim report and the sample and well data in electronic format PGWDB data
elements are listed on page OV-4 of this report Electronic media should be accompanied
by a description that includes, hardware compatibility (IBM, Apple etc.), operating system
(DOS, UNIX, OS2), format identification (ASCII or software package name) and a data
dictionary. Anyone wishing to provide comments or data may do so by contacting:
Constance A. Hoheisel
U. S. Environmental Protection Agency
Office of Pesticide Programs
Environmental Fate and Effects Division (H7507C)
401 M Street, SW
Washington, DC 20460
Telephone: 703-305-5455
FAX: 703-305-6309
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REFERENCES
1. Hoheisel, C. and Davies-Hilliard,L. Pesticide Infonnation Network U.S. Environmental
Protection Agency, Office of Pesticide Programs, Washington D.C.,1987. Database-
703-305-5919. User Support: 703-305-7499.
2. Spencer, D.A. The National Pesticide Monitoring Program. U.S. Environmental
Protection Agency, 1974. Summary document published by The National Agricultural
Chemicals'Association.
3. U.S. Environmental Protection Agency. The National Survey of Pesticides in Drinking
Water Wells. Washington, D.C., 1990. For Fact Sheets contact: EPA Public
Information Center, 202-260-2080. For copies of reports contact- National Technical
Infonnation Service (NTIS), 703-487-4650.
4. Williams, W.M.,Holden, P.W.,Parsons, D.W. and Lorber, M.N. Pesticides in Ground
Water Data Base-1988 Interim Report. U.S. Environmental Protection Agency, Office
of Pesticide Programs (H7507C), Washington, D.C.,1988.
5. U.S. Environmental Protection Agency, Office of Information Resources Management
STORET (Water Quality Database). Washington, D.C. User assistance: 1-800-424-
9067.
6. U.S. Geological Survey, National Water Data Exchange. WATSTORE(Water Quality
Database). Reston, VA. For further information: 703-648-5671.
7. U.S. Environmental Protection Agency, Office of Water. Drinking Water Regulations and
Health Advisories. Washington, D.C., November 1991. Tel: 202-260-7571.
8. U.S. Environmental Protection Agency, Office of Ground Water and Drinking Water
Definitions for the Minimum Set of Data Elements for Ground-Water Quality.
Washington, D.C.,1991.
OV-13
-------
Well Sampling by State
(Total Number of Wells with Peflfcfcte Detections/Total Number of Wells Sampled)
Region VIII
UT
••••%• •• •. .v.'
Total Wells Sampled
per State
• > ieee
ra 581 to 1998
E3 181 to 588
CZ 51 to 188
E3 1 to 58
CD No wells sampled
OV-14
-------
REGION 8
WELL STATUS BY STATE
DESCENDING BY NUMBER OF WELLS WITH DETECTIONS
SD
WY
ND
MT
0
CO
UT
NO DATA AVAILABLE
I
100 200 300
WELL COUNTS
400
500
WELLS WITH DETECTIONS >= MCL
TOTAL WELLS SAMPLED
WELLS WITH DETECTIONS
OV-15
-------
Pestidda in Ground Water Database -1992 Report
STATE SUMMARIES
-------
Watt Sampling by County
(Total Number of Wells with Pesticide Detections/Total Number of Wells Sampled)
Colorado
Total Wells Sampled
per County
E3
> 1000
501 to 1000
101 to 580
51 to 100
1 to 58
O No wells sampled
Pesticides Detected
Atrazine
8-CO-l
-------
COLORADO
OVERVIEW OF STATE LEGISLATIVE AND ENVIRONMENTAL POLICIES
REGARDING PESTICIDES IN GROUND WATER
In 1987 Colorado established ground-water regulations to be enforced by the Water Quality
Control Commission under the Colorado Department of Health. The purpose of the
regulations was to establish statewide standards and a system for classifying ground water,
and to adopt water quality standards for ground-water classifications to protect potential
beneficial uses of ground water. Most people in Colorado are not dependent on ground
water for domestic use; surface water is the main source for the more populated areas of
the state.
As a result of the 1987 legislation, and subsequent amendments, several studies on pesticides
in ground water were initiated by the Ground Water Unit of the Colorado Department of
Health. A 32-well pilot program was conducted in the northeast corner of the state starting
in 1989. This program was later expanded to include well sites in the south central part of
the state. Data from these studies are going to be incorporated in a database on ground-
water quality of the major aquifers. At the time that The Pesticides in Ground Water
Database Report was being prepared, these data were not yet available. We look forward
to including them in subsequent years.
REPORTED STUDIES OF PESTICIDES IN GROUND WATER
Savage, E.P., M.P. WUson, JJ. Aaronson, TJ. Keefc and IT. Tessari, and D.H. Hamar,
Colorado State University, Institute of Rural Environmental Health and Department of
Pathology, Tel: 303-491-6281. Groundwater Transport of the Herbicide Atrazine, Weld
County, Colorado. Study conducted July to November 1985. (Reported 1987, 12 pp.)
Primary Objective
The purpose of this study was to monitor ground water at gradient points above, directly
beneath, and below an atrazine-treated site in the South Platte River Valley of Weld
County.
Design
The study site was selected because it is representative of the general conditions under
which atrazine enters the agricultural environment of the South Platte River Valley.
Characteristics of bydrogeology, agriculture and soils were considered in selecting the site.
The site measures 1 by 3 miles with the long axis parallel to the underlying ground-water
flow. The ground-water gradient slopes downward from south to north. Ground water
beneath the study site is hydrologically isolated from underflow from the direction of the
8-CO-3
-------
south end of the site. Within the study she are 240 acres that are annually planted to field
corn. Pre-emergent broadleaf weed control on this acreage has been managed for more
than 20 years by the use of atrazine. The soils to which atrazinc was applied are primarily
sandy loams: level, deep, well-drained, and moderately to rapidly permeable.
Four water wells were identified that allowed the collection of ground water at gradient
points above (Well IX beneath (Well 2), and below (Wells 3 and 4) the atrazine-treated
fields. Water samples were collected from each of the four weDs on nine occasions at two-
week intervals beginning 31 Jury 1985 and ending 20 November 1985. Samples of ditch
water used for center pivot irrigation were also collected to determine the atrazine
contribution made by this source to the atrazine-treated fields. Ditch water samples were
also collected at two-week intervals but only between 31 July and 23 October 1985; ditch
water flow was inadequate for sampling after the latter date. Samples were analyzed by
GC/NP. Identification of atrazine was confirmed by GC/MS. The detection limit of the
GC analysis of atrazine was 0.80 ug/L.
'Results and Conclusions
Based on analysis of samples from Well 1, there did not appear to be measurable atrazine
contamination in study site ground water prior to its movement beneath the atrazme-treated
fields. Trace positive levels of atrazine (below the detection limit of 0.80 ug/L) were
detected in samples up to 9 October; atrazine was not detected after that date. Atrazine
was also detected at trace levels in Well 3, located immediately below the study site. In this
case, low atrazine levels were attributed to the peripheral location of Well 3; water pumped
from Well 3 probably included water from east of the atrazine-treated fields. Thus, dilution
of the ground water from beneath the treated fields would have occurred.
Both Well 2 (located beneath the study site) and Well 4 (located about one-half mile below
the site) yielded ground-water samples with measurable atrazine concentrations for all
sampling dates. Atrazine levels ranged from 1.1 to 1.8 ug/L in Well 2 and from 23 to 13
ug/L in Well 4. Levels of atrazine decreased over time in samples collected from Well 4.
All detections were below the maximum contamination level (MCL) for atrazine of 3 ug/L
the linear correlation between atrazine concentration and tune was statistically significant
for the data from Well 4 (0.001 < p < 0.002); atrazine concentrations were estimated to
decrease at a rate of .0094 ug/L per day. Atrazine levels in Well 4 samples were
determined to be representative of points along the concentration gradient of a contaminant
plume moving past the well. This gradient is the result of atrazine transport processes.
Within the time limits of this study, the cessation of irrigation of the atrazine-treated fields
did not produce a corresponding decrease in the level of atrazine in ground water.
Based on data for irrigation rates and the atrazine application rate, irrigation water would
account for only 0.52 percent, at a maximum, of the total atrazine load to the,treated fields.
Thus, the levels of atrazine detected in ditch water would have a very small relative impact
on ground water below the treated fields. Atrazine was detected in one ditch water sample
at 1 ug/L, and in 5 samples at trace levels.
8-CO-4
-------
KSTICI8C SMPLIK M WE STATE OF COLOMBO
TOTAL DISCRETE
WELLS/SAMPLES
GRAND TOTAL
DISCRETE
UELLS/SAMPLES
STATE OF COLORADO
IELLS BY COUHTT
NFUaKnown or Suspected Normal Field Use
PS "Known or Suspected Point Source
UNX*UnknoMn
8-CO-5
-------
Well Sampling by County
(Total Number of Wells with Pesticide Detections / Total Number of Wells Sampled)
Montana.
Total Wells Sampled
per County
m > 1000
W 501 to 1000
E3 101 to 500
Z) 51 to 100
E3 1 to 50
O No wells sampled
Pesticides Detected
Aldicarb SuIIone Dicamba
Aldicarb Sulfoxide MCPA
Atrazine Piclomm
2, 4—D Simazine
8-MT-l
-------
MONTANA
OVERVIEW OF STATE LEGISLATIVE AND ENVIRONMENTAL POLICIES
REGARDING PESTICIDES IN GROUND WATER
Ground water is an important source of domestic and agricultural water in Montana.
Montana has been monitoring its ground water for contaminants since 1984. At that time
the Montana Department of Agriculture received a grant from the USEPA to study the
occurrence of agricultural pesticides in ground water. This monitoring program was
designed to gather baseline information on the occurrence and extent of such contamination
throughout the state. The MDA chose to concentrate its efforts on areas that had a history
of pesticide use.
REPORTED STUDIES OF PESTICIDES IN GROUND WATER
DeLuca, T., J. Larson, L. Torma, and C. Algard, A Survey of Gronndwater Contamination
by Pesticides in Montana. Montana Department of Agricuture, Environmental Management
Division, Technical Report 89-1, August 1989. Additional contact Phil Johnson, Montana
Department of Agriculture, Telephone (406) 444-2944.
Primary Objective
The objective of this study was to analyze water samples from domestic,, livestock, and
irrigation wells in several distinct agricultural production regions in Montana and determine
whether Montana has a ground-water contamination problem worthy of further study or
immediate action. Over a 5 year period, the monitoring program was expanded and
adjusted to broaden the scope and database of this investigative monitoring study.
Design
The study was designed to gather baseline information concerning ground-water
contamination by pesticides and to determine the need for further study. Areas and
pesticides were selected based on the greatest potential for ground-water contamination,
taking into consideration crops grown, production practices used, and pesticides applied.
Site selection was divided into five major groups.
1. Seed potato production in Flathead, Lake and Gallatin Counties
2. Sugarbeet production along the Yellowstone River
3. Hay production in Southwestern Montana
4. Irrigated small grain production in the Triangle area
5. Chlorsulfuron use region in Northeastern Montana
The number of times a site was sampled during any one year or over the five year span was
dependent on previous findings or changes in pesticide use patterns.
8-MT-3
-------
Pesticide anatytes and detection limits in ug/L:
iflymncmorniB
ImedieidM
Aldrin
t-Nonachlor
Oxychlofdane
DDT
DDD
DDE
DieUrin
Heptaehlor
Heptachlor
.epoxide
Hcxachloro-
benzene
Methoxychlor
Mirex
Toxaphene
0004
003
0.008
0.008
,042
O01
O007
0407
OJQ1
0403
0408
OJOQ3
0404
042
OS
Inmtiffiita
Aldkaib
Akficaib
Aldkaib sotfone
Ctrbaryl
Carbo&ran
3-Hydroxy-
HIM n ra lira n
Methomyl
OivanoDhosohate
CUorpyrifos
DiazinoD
Ethyl Parathioa
Metibyl Parathion
Tobofos
LO
20
20
20
IS
20
OS
041
041
042
041
041
14
AHKlUaX
HeifriddM
2^-D
2,4-DB
MCPA
Meooprop
SOvex
iw
03
as
•
02
• •
01
01
^2Ugn£
HerfaiddM
Atrazine
Other
HetbicideR
Cydoato
^vlC82BDtt
Pidoram
01
LO
•Not provided
Conclusions
During the 5 year sampling period of this ground-water survey, 23 wells in different regions
of Montana were observed to be contaminated by 7 different pesticides. Over 230 samples
were analyzed, and approximately 25% were positive for the presence of pesticide residues.
None of the residues detected in the program suggest any immediate drinking water health
risk. Though no pesticides were detected in Beaverhead, Daniels, Flathead, Gallatin, Hill,
Lake, and Valley Counties, the geographic area and the types of pesticide covered by this
survey are far to limited for this result to be conclusive. Pesticide contamination in well
water of Carbon, Jefferson, Richland, Sheridan, Teton, and Yellowstone Counties is
conclusive in that it documents pesticide contamination of ground water in Montana and
suggests the need to continue studying the extent of contamination.
This ground-water monitoring study allowed Montana to identify the presence of ground-
water contamination by pesticides in several regions of the state. Both point source and
non-point source ground-water contamination by pesticides were observed during the 5 year
period. Though the study identified no immediate drinking water health threat (only one
pesticide residue was in excess of the lifetime drinking water health advisory standards), the
information does not preclude it's occurrence. Within the limited scope of this monitoring
program, the occurrence of pesticide residues in ground water is primarily the result of a
combination of soil type, precipitation (or irrigation), leaching potential of the pesticide, and
depth to water table. Future monitoring programs will take a closer look at these factors
when identifying sampling sites.
8-MT-4
-------
PESTICIDE SMPLIK U TK STATE OF NBTMM
2,4-0 to DOE
8-MT-5
-------
SMVLIK II IK STATE OF HMT/UM
2.4*0 to DOE
TOTAL DISCRETE
WELLS/SAMPLES
8-MT-6
-------
PESTICIDE MNPLIK M IK STATE OF NOMTMU
2,4-0 to DOE
TOTAL DISCRETE
HELLS/SAMPLES
8-MT-7
-------
PESTICIDE SMPLMB U TK tlUE OF OffMtt
2,4-0 to DOE
TOTAL DISCRETE
UELIS/SMPLES
8-MT-8
-------
riCDE SMVLIK U TK STATE OF MMTAM
2,4-D to DOE
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
8-MT-9
-------
PESTICIBC SMPLIK II TK SEME OF MVTMtt
2,4*0 to BOE
TOTAL DISCRETE
WELLS/SAMPLES
8-MT-10
-------
PESTICIDE SAMPLING II IK STATE OF MVTANA
2,4-0 to ODE
TOTAL DISCRETE
WELLS/SAMPLES
8-MT-ll
-------
PESTICIDE SMP1W U TK SM1E OF KVTMM
2,4-0 to 006
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
8-MT-12
-------
SMPLIK M TK STATE OF MONTANA
2,4-0 to DOE
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
8-MT-13
-------
KSTICIOE MNPLHB H IK STATE Of ROTAM
2,4*0 to OOE
TOTAL DISCRETE
TOTAL DISCRETE
UELLS/SANPLES
TOTAL DISCRETE
UELLS/SANPLES
TOTAL DISCRETE
WELLS/SAMPLES m
TOTAL DISCRETE
WELLS/SAMPLES
8-MT-14
-------
PESTICIDE SWPLIN6 U TK STATE OF NMTAW
2,4-0 to ODE
1984/7
1986/2.3
1984/6
1984/6.8
15
1986/3.5
TOTAL DISCRETE
WELLS/SAMPLES
22
.29
1984/7
1986/2.3
1984/6
1984/6.8
15
1986/3,5
TOTAL DISCRETE
WELLS/SAMPLES
29
MK" ~ ~3Sk*x
1984/7
1986/2.3
1984/6
1984/6.8
15
1986/3.5
TOTAL DISCRETE
WELLS/SAMPLES
22
29
8-MT-15
-------
PESTICIDE SWLIMG U TK STATE OF KXTAM
DiCMte to
8-MT-16
-------
PESTICIDE SNVLIW IN TK STATE OF NONTAM
to Toxaphcne
TOTAL DISCRETE
WELLS/SAMPLES
8-MT-17
-------
KSriCUE SMPLIK II 1C SIKIE OF MVTAM
DfcMta to TouplMnt
(DiehloreroD)
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
UELLS/SAW>LES
TOTAL DISCRETE
WELLS/SAMPLES
RATtCAfr /% i
TOTAL DISCRETE
WELLS/SAMPLES
8-MT-18
-------
PESTICIDE SMPLIKG IN TC STATE OF NMTMM
to Toxtphtne
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
8-MT-19
-------
PESTICIDE ttNPUK II HE STATE V IOTAM
Dievto to Touptwrn
TOTAL DISCRETE
WELLS/SAMPLES
8-MT-20
-------
STICIOE SMTLING » TK STATE OF KVTMM
OicMba to Toxaphmt
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
8-MT-21
-------
PESTICIDE SMVLIK II T* STATE OF «TAM
DfcMta to
TOTAL DISCRETE
UELLS/SAMPLES
8-MT-22
-------
PESTICIDE SMPLIM6 II TC STATE OF NQNTMtt
to Toxaphtrw
TOTAL DISCRETE
UELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
8-MT-23
-------
PESTICIDE SMPL1K M TK STATE OF NCMTAM
DfCMbt to Touphmt
TOTAL DISCRETE
UELIS/SANPLES
GRAND TOTAL
DISCRETE
NELLS/SAMPLES
8-MT-24
-------
STATE OF MKTMU
IEL1SIT COUITT
NFU»Knoun or Suspected Normal Field Use
PS «Known or Suspected Point Source
UNK*UnknoMn
8-MT-25
-------
Well Sampling by County
(Total Number of Wells with Pesticide Detections / Total Number of Wells Sampled)
IsTor-th. Deulcotex
:4J/2X:
Total JTeJIs Sampled
per County
m > leee
@ 581 to 1066
K3 101 to see
El 51 to 100
E3 1 to 50
O No wells sampled
Pesticides Detected
Alachlor
Methyl Parathion
Picloram
Trifluralin
8-ND-l
-------
NORTH DAKOTA
OVERVIEW OF STATE LEGISLATIVE AND ENVIRONMENTAL POLICIES
REGARDING PESTICIDES IN GROUND WATER
North Dakota is located in the upper Great Plains of the US. The majority of its population
live and work in a rural environment There are approximately 340 community drinking
water systems scattered in various locations throughout the state, most serving less than
1,000 individuals. Ground water resources are the primary source of water used for these
systems. Since agriculture and agricultural activities constitute the major economic base for
the state, the levels of agricultural chemicals in the soil environment and the possible
migration into ground-water resources have become issues of concern.
REPORTED STUDIES OF PESTICIDES IN GROUND WATER
Glatt, L. David, Environmental Engineer, North Dakota State Department of Health and
Consolidated Laboratories, Tel: 701-224-2354. Pesticide and Herbicide Survey of Selected
Municipal Drinking Water Systems in North Dakota. Study conducted during Fall 1985.
(Reported 2/86, 33 pp.)
Primary Objective
This study was initiated to determine the occurrence of agricultural compounds (aldicarb,
fenvalerate, picloram, methyl parathion, and 2,4-D) in municipal drinking water systems in
52 counties of North Dakota.
Design
The sample collection from municipal drinking water systems was concentrated in those
areas which appeared to exhibit the greatest potential for ground- or surface-water
contamination. Criteria used in the selection of sample sites included municipalities which
derive their water primarily from shallow ground water, or are located near regions of
water-permeable soils, shallow ground-water tables, heavy irrigation, or heavy agricultural
chemical application. At least one municipal drinking water supply system was chosen from
52 of the 53 counties in North Dakota. Samples were collected prior to water treatment
processes from 85 municipal drinking water supply systems that receive water through
ground-water resources, and seven which are supplied through surface water. The samples
were analyzed for one or more of the following chemicals: 2,4-D by GC; aldicarb by LC;
picloram, trifluralin, parathion, and fenvalerate by GC/ECD. The detection limits were as
follows: (1) picloram, 0.8 ug/L; (2) 2,4-D, 0.02 ug/L; (3) fenvalerate, 4.0 ug/L; (4) aldicarb,
0.7 ug/L; (5) parathion, 0.02 ug/L; and (6) trifluralin, 0.07 ug/L.
8-ND-3
-------
Ten (9 ground water and 1 surface water) of the systems surveyed indicated the presence
or possible presence of at least one typt of agricultural chemical The compound detected
in seven of the positive samples was the selective broadleaf herbicide picloram. All but one
of these samples were from ground-water supplied systems. Suspected concentrations of
ethyl parathion, methyl parathion, and trifhiralin were detected at three separate sampling
sites. Hie concentrations detected were near me detection limits for these compounds,
therefore there is some question concerning the accuracy of these detections.
Glatt, JL David, Environmental Engineer, North Dakota State Department of Health and
Consolidated Laboratories, Tel: 701-224-2354. 'Gronndwater Investigation to Determine
the Occurrence of Picloram in Selected Well Sites of Rolette County, North Dakota.* Study
conducted in July and August, 1985. (Reported 12/85,35 pp.)
Primary Objective
The purpose of this monitoring study was to determine whether Tordon (picloram) was
present in drinking water systems in the Shell Valley and Rolla Aquifers in Rolette County,
ND, due to routine usage of picloram for the eradication of leafy spurge.
Design
Sample site selection concentrated on regions that exhibited the greatest potential for
ground water concentration due to picloram application. Considerations in the selection of
the sample sites included the proximity of shallow ground-water tables and permeable soils
to areas treated with picloram within recent years. A total of 137 samples were collected
from 126 drinking water wells. Approximately 85 samples were collected from wells
supplied by the Shell Valley Aquifer, 15 from the Rolla Aquifer system and 26 samples from
other locations outside of the major aquifer boundaries. Samples were analyzed
approximately 7 days after collection for picloram by GC/MS. The majority of the samples
were collected during the last week of July and first week of August 1985. Well depth, year
of construction, diameter, static water level, and locations of picloram application activity
were also reported. The detection limit was 0.02 ppb.
Results and Conclusions
Eleven of the samples exhibited evidence of at least a trace (<0.02ug/L) of picloram, with
a high concentration of 0.85ug/L. Eight of the 11 positive samples were from private wells
used by single family residences or livestock watering. The remaining three samples were
collected from municipal drinking water wells. All of the positive wells were considered
shallow (depth from 15-60 feet), with well casing diameters of 125 to 24 inches. A
subsequent sample was collected from each positive sampling site to confirm the original
sample results. None of the municipal wells and four of the private wells were positive at
re-sampling.
8-ND-4
-------
Lym, Rodney G. end C Messersmith, Associate Professor and Professor, respectively, North
Dakota State University, Tel: 701-237-7971. 'Surrey for Pidoram in North Dakota
Groundwater." Study conducted 1985-86. (Reported in Weed Technology, VoL 2217,1988
p. 217).
Primary Objective
This study was conducted to determine the occurrence of picloram in drinking water systems
in ten counties of North Dakota (Burleigh, Pierce, Stutsman, Ward, Wells, Morton, Stark,
Williams, Cass, and Dunn) due to routine usage of picloram for the eradication of leafy
spurge.
Design
Ten North Dakota Counties were chosen for sampling based on picloram usage during an
active leafy spurge control program and on maintaining a representative cross-section of
climate, soil, type, and geological formation. In 1985, 144 drinking water wells were
sampled. Each well was sampled three times; in early June before spray season, in mid-July
immediately after spray season, and in September to detect possible changes in herbicide
concentrations with time. Wells were located in the following counties: Burleigh, Pierce,
Stutsman, Ward, Wells, Morton, Stark, Williams, Cass, and Dunn. Wells containing
picloram in 1985 were resampled in April and September 1986. An additional 44 wells
were sampled only in 1986. These wells were located within 2 km of wells where picloram
was detected in 1985. All the wells were located in a glacial drift formation. The samples
were analyzed for picloram by HPLC. The detection limit was 0.05 ppb.
Results and Conclusions
Picloram contamination of North Dakota ground-water was widely scattered. Picloram was
found in five wells in five counties in 1985, and all were within 1.5 km of an area treated
for leafy spurge control. Picloram was present at concentrations from <0.1 to 12.8 in
Burleigh, Ward, Wells, Morton, and Williams Counties. These counties are located in both
eastern and western North Dakota. The five positive wells were resampled in 1986 and
three were positive for picloram in Morton, Wells and Williams counties. Picloram was
found in only one of the 44 additional wells sampled in 1986. It was detected at 0.97 ug.L
in April and < 0.1 in September in a domestic livestock well on the Morton county
farmstead. A follow-up survey of well owners revealed that in all cases except one, a
picloram-contaminated well either had been used to fill a sprayer and the owner recalled
a spill or picloram had been applied to a nearby area where the water table was within 4m
of the surface. The highest concentration found in this survey was 12.8 ug/L. This is well
below the MCL of 500 ug/L. While water from contaminated wells may not be considered
a health hazard, minute amounts of picloram could adversely affect sensitive crops grown
under irrigation.
8-ND-5
-------
Pnmty, Lyle and B. H Montgomery, Department of Soil Science, North Dakota State
University, Tel: 701-237-7556 (Montgomery). Temporal Pesticide Leaching Through
Irrigated Sandy Loam Soil" Study conducted 1985-87. (Reported 10/87,41 pp.)
Primary Objective
The purpose of this research was to provide baseline aquifer information concerning nitrates
and pesticides under various irrigated and non-irrigated cropping systems.
Design
the environmental impacts of irrigation development on a surfitial aquifer. The Test Area
covers 3,100 hectares (7,600 acres) and is over 95% agricultural land. It is well-suited for
ground-water quality studies, as it has sandy soils and a high water table and rapidly
increasing irrigation acreage. Dominant crops within the Test Area are com and small
grains. Com received the bulk of the herbicide application even though the crop occupied
only 30% of the land area. Ninety-five percent of the corn acreage received at least one
herbicide wnfle only 50% of the non-com acreage received at least one herbicide.
There were three sources of sample data established in this study: observation wells for
obtaining samples from the lower portion of the aquifer; tile drain lines near the level of
the water table; and lysimeteis for monitoring directly the percolating water beneath the
root zone. The wells are located on a 1/2-mile grid over the entire test area with a total
of 98 wells available. The entire area is drained by subsurface tile drainage system accessed
by manhole point, 16 of which were monitored in this study. Four large lysimeters were also
sampled. The samples were analyzed for atrazine and simazine by HPLC, and for alachlor
and metolachlor by GC The detection limits were 1 g/L for all four chemicals.
Results and Conclusions
Six of the 229 samples taken from 1985-1987 were positive for alachlor: 3 samples were
from a single well, 2 lysimeter samples, and 1 tile drain sample. Positive values ranged from
0.05 to 1.2 ppb. Contamination in the well with the 3 positive samples may have been from
tank mixing and rinsing or a spill since it was rather isolated from agricultural applications.
No alachlor was found in neighboring wells. Non of the other three herbicides (atrazine,
simazine, metolachlor) were detected in any of the samples.
8-ND-6
-------
PESTICIDE SAMPLING IN THE STATE OF NORTH DAKOTA
1985/Fall
1985/Fall
1985/Fall
1985/Fall
1985/Fall
1985/Fall
1985/Fall
1985/Fall
1985/Fall
1985/Fall
1985/Fall
1985/Fall
1985/Fall
1985/Fall
GRAND FORKS "
1985/Fall
GRAM?
1985/Fall
GRfGGST
1985/Fall
1985/Fall
1985/Fall
LOSAtt
1985/Fall
1985/Fall
HCWTOSW
1985/Fall
1985/Fall
MCtEAN
1985/Fall
MERCER
1985/Fall
MORTON
1985/Fall
WUNTRAU
1985/Fall
KELSON
1985/Fall
P6HD1NA
1985/Fall
8-ND-7
-------
PESTICIDE SAMPLING IN THE STATE OF NORTi DAKOTA
TOTAL DISCRETE
UELLS/SAHPLES
TOTAL DISCRETE
WELLS/SAMPLES
8-ND-8
-------
PESTICIDE SAMPLING IN THE STATE OF NORTH DAKOTA
7\
•} s^l^»
> •<. •*•
"•&••& \ ~- -^ ^^
•STOJ* >
<**^«*
(Atdicarb)
imf-4!^
,. .,. * *J^^
-^.^Xl^H-
'^'C't "'X; "• vC1*1^^..
1985/FaU
1985/Fall
, «j&s ''" '' "
tarn* - *><*
1985/FaU
Tfi*:
1985/Fall
.AJAt^»
1985/FaU
\i.
«i
.CeuBty
1985/Fall
TOTAL DISCRETE
WELLS/SAMPLES
17
17
s«o ^
A trail ne
JIS
.^.. . . <"4 ^^%-, >v\ M
-oitag^--- :" ^-
1985-87
212
TOTAL DISCRETE
WELLS/SAMPLES
fenvsterates
212
BARNES
1985/Fall
BENSON
1985/Fall
feOTTBIEAU
1985/FaU
BtJRLEIGH
1985/FaU
tfts£
1985/FaU
CAVALIER
1985/FaU
DICKEY
1985/Fall
EPPY
1985/Fall
EMMWS
1985/FaU
*OSTE*
1985/Fall
GRAND FORKS
1985/FaU
CRIC6S
1985/FaU
KIDOER
1985/FaU
U HOORE
1985/FaU
LOGAM
1985/FaU
HCHEMRY
1985/Fall
KCMTOSH
1985/FaU
MC£.*AH
HEtSON
1985/FaU
1985/FaU
8-ND-9
-------
PESTICIDE SMPLIHG IH THE STATE OF NORTH DAKOTA
(Fenvalerate)
1985/FaU
1985/Fall
1985/Fall
1985/FaU
1985/FaH
1985/FaU
f ^V'^
801ITTE
1985/FaU
1985/Fatl
1985/FaU
1985/FaU
1985/FaU
1985/FaU
1985/FaU
1985/FaU
1985/FaU
mis
1985/FaU
County ""
1985/FaU
TOTAL DISCRETE
WELLS/SAMPLES
58
TOTAL DISCRETE
WELLS/SAMPLES
8-ND-10
-------
PESTICIDE SAMPLING IN THE STATE OF NORTH DAKOTA
1985/FaU
RE150N-,
1985/FaU
1985/fall
1985/FaU
1985/FaU
1985/FaU
1985/FaU
SAftCEJiT'"..
1985/FaU
1985/FaU
1985/FaU
StUTSXAtl
1985/FaU
TOWMES
TOTAL DISCRETE
WELLS/SAMPLES
BENSON
6URLE1GH
'CASS
DICKEY
EDDY
•EMHONS
CTIGGS
K1DOER
tA HOURE
tOGAN
1985/FaU
1985/FaU
1985/FaU
1985/FaU
1985/FaU
1985/FaU
1985/FaU
1985/FaU
1985/FaU
1985/FaU
1985/FaU
0.04
8-ND-ll
-------
PESTICIDE SAMPLING IN THE STATE OF NORTH DAKOTA
TOTAL DISCRETE
VELLS/SAMPLES
8-ND-12
-------
PESTICIDE SAMPLING IN THE STATE OF NORTH DAKOTA
1985/FaU
1985/Fatl
«i*»xrW**v
1985/Fall
1985/Fall
1985/FaU
1985/Fall
1985/Fall
lOCAN
, ' ••••^
1985/FaU
1985/Fall
0.21
1985/Fall
1985/Fall
MCLfiAM
1985/Fall
HERGES
1985/Fall
MORTON
1985/FaU
1985/6.7.9
16
0.4-0.5
1986/4,9
0.1-0.97
HOUHTSAft.
1985/Fall
0.08
HEtSOH' -
1985/Fall
PENDINA
1985/Fall
P1ERC6
1985/FaU
0.2
1985/6.7.9
12
36
RAMSEY
1985/Fall
1985/FaU
0.2
REHVtlti
1985/Fall
RTCHtAW)
1985/FaU
1985/FaU
1985/7-8
126.
11
137
15
<0.02-
3.56
8-ND-13
-------
PESTICIDE SAMPLING IN THE STATE Of NORTH DAKOTA
1985/FaU
1985/6.7.9
14
1985/Fall
1985/FaU
1985/FaU
1985/FaU
1985/6.7.9
19
57
1986/4.9
mts
1985/FaU
1985/6.7.9
16
48
12.4-12.8
1986/4.9
6.7-8
1985/FaU
1985/6,7,9
14
42
2.2-2.4
1986/4.9
TOTAL DISCRETE
WELLS/SAMPLES
1896/4,9
41
82
L
TOTAL DISCRETE
WELLS/SAMPLES
L
400
23
1163
39
<0.02-
12.8
106
106
212
212
8-ND-14
-------
PESTICIDE SAMPLING IN THE STATE OF NORTH DAKOTA
TOTAL DISCRETE
WELLS/SAHPLES
GRAND TOTAL
DISCRETE
WELLS/SAMPLES
Additional wells sampled near positive wells from the 1985/6,7,9 sampling. Wells are located in one of the
following counties: Burleigh, Norton, Ward, Wells, Williams.
8-ND-15
-------
STATE OF NORTH DAKOTA
UELLS BY COUNTY
% J*,' x \" v--5'-''
SOttnanV^: '^t
17
14
113
16
Foster
cotden VaUey
firand Forks
hettfnger "
Moure
Logan
XCH6BPV
Mclntosh
HcKenzie
HcLftfift
Mercer
19
Net son
8-ND-17
-------
STATE OF NORTH DAKOTA
UEU.S BY COUNTY
13
129
11
'
u
Statmmn
16
Ward
21
Wet Is
18
16
402
26
113
19
10
NFU=Known or
PS =Known or
UNK-Unknoun
Suspected Normal Field Use
Suspected Point Source
8-ND-18
-------
Well Sampling by County
(Total Number of Wells with Pesticide Detections / Total Number of Wells Sampled)
South Dakota
Total Wells Sampled
per County
• > 1000
m 501 to 1000
E3 101 to 500
[3 51 to 100
E3 1 to 50
n No wells sampled
Pesticides Detected
Alachlor Fonofos
Atrazine
Cyanazine
2,4-D
Dicamba
Lindane
Metolachlor
Metribuzin
Picloram
Trifluralin
8-SD-l
-------
SOUTH DAKOTA
OVERVIEW OF STATE LEGISLATIVE AND ENVIRONMENTAL POLICIES
REGARDING PESTICIDES IN GROUND WATER
An estimated 93% of South Dakota's land area is farmed and 75% of its population relies
on ground water as a source of drinking water. A great concern of the people of South
Dakota is the potential effects of modern pesticides an fertilizers on their drinking water
supplies. The South Dakota Department of Natural resources designated Water Quality
Study areas in east-central South Dakota which originally studied surface water and later
expanded to examine ground water quality. Monitoring of surface and ground waters have
been carried out since the early seventies as part of South Dakota's Statewide Water Quality
Management Plan. In the early eighties two of these sites were combined and qualified for
research money under USDA's Rural Clean Water Program (RCWP). The final Oakwood
Lakes-Poinsett RCWP area covers portions of four counties.
In 1988 the South Dakota Legislature directed the Department of Water and Natural
Resources to undertake a sampling program to assess the presence and extent of pesticides
and nitrogen-based fertilizers in ground water. This pilot program was expanded in 1989
to cover additional aquifers. The South Dakota Groundwater Law, enacted in 1989,
stipulates that, in conjunction with the South Dakota Department of Agriculture, State
universities, and other interested parties, the secretary of the Department of Water and
Natural Resources will annually review new studies and data that relate the use of pesticides
and fertilizers to the quality of South Dakota's waters. Based on the information obtained,
the State will formulate and revise state management plans for the use of pesticides and
fertilizers which will prevent ground-water contamination.
REPORTED STUDIES OF PESTICIDES IN GROUND WATER
Tel: 605-773-3296.
Primary Objective
This report was intended to provide an overview of the status of pesticides in ground- water
monitoring efforts and potential health risks associated with pesticide occurrence in South
Dakota through 1986. Three studies in which pesticides had been detected in ground water
were included in the report:
8-SD-3
-------
(1) the Oakwood Lakes-Poinsett RCWP, which includes a 10-year Comprehensive
Monitoring and Evaluation Project administered by the Agricultural Stabilization and
Conservation Service (ASCS), the Soil Conservation Service (SCS), and the South Dakota
Department of Water and Natural Resources (DWNR);
(2) a 1985 sampling of selected shallow Public Water Supplies (PWSs); and
(3) ground-water investigations by the South Dakota Geological Survey (SDGS).
The bulk of the report discussed the characteristics and toriciry of 21 pesticides that had
detected in ground-water, were considered a potential health risk, and were used in South
Dakota.
Design and Results
Details of the monitoring studies mentioned were not provided in this summary report
Study design and results of the Oakwood Lakes-Poinsett RCWP are provided below.
Ten PWSs were sampled in 1985. Pesticides were detected in samples from 3 of the 10
supplies. In one of these cases (unspecified), the source of the contamination was
determined to be poor handling and disposal practices.
As a result of ground water investigations by the South Dakota Geological Survey pesticides
were detected in monitoring wells in Alcester and Union Counties.
The following table was presented in the report to summarize pesticide detections in South
Dakota before 1986:
County
Alcester, Union
Bruce, Brookings
Egan, Moody
Brookings
Well Type
SDGS
Observation
Main PWS
Standby PWS
RCWP
Pesticide
Alachlor
Atrazine
Alachlor
Atrazine
Picloram
alachlor
2,4-D
Cone.*
3.1
1.7
3.2-6.7
5.8-7.1
8.3
0.16-3.09
0.29-0.8
LOD-
0.05
05
0.05
05
0.1
0.05
0.1
Concentration, and Limit of Detection are in ug/L
Bender, A.R, Project Leader and Contact, Water Resources Institute, South Dakota State
University, Oakwood Lakes-Poinsett Rural Clean Water Program. Tel.: 605-688-4910. 1987
Annual Progress Report - Project 20 and CM&E Technical Report (Water Quality Land Use
Data Analysis). Study conducted January 1984 through July 1987. (Reported 1987,181 pp.)
Analysis and evaluation of field site ground-water monitoring by C.G. Kimball (Principal
Investigator), and WA. Best (Research Assistant).
8-SD-4
-------
Primary Objective
The goal of the Oakwood Lakes-Poinsett Rural Qean Water Program (RCWP)
Comprehensive Monitoring & Evaluation Plan (CM&E) is to improve and protect the
surface- and ground-water quality of the project area by the application of selected Best
Management Practices (BMPs). The overall goals of the RCWP project to:
(1) reduce the amount of total nitrogen and pesticides entering the ground and surface
water by assisting with fertilizer and pesticide management on 70,000 and 65,000
critical acres, respectively;
(2) reduce the amount of water- and sediment-borne pollutants entering waterways and
lakes by applying or maintaining conservation tillage on 65,000 critical acres;
(3) reduce the amount of animal waste entering waterways, lakes, and ground water by
applying waste management systems on 10 livestock operations.
The specific objective of the CM&E project is to monitor the effect and to evaluate the
impact on ground- and surface-water quality of selected BMPs that have been implemented
by the RCWP. BMPs that have been initiated include conservation tillage, fertilizer
management, and pesticide management.
Design
Fifty-seven monitoring wells in Hamlin (40) and Brookings (17) Counties were selected for
continued monitoring of ground-water quality, including analysis for 22 pesticides: alachlor,
atrazine, butylate, chloramben, carboruran, cyanazine, 2,4-D, dicamba, endrin, EPTC,
fonofos, lindane, methoxychlor, metolachlor, metribuzin, parathion, phorate, picloram,
propachlor, terbufos, toxaphene, and trifluralin. The wells sampled for pesticides are part
of a network of 114 monitoring wells installed by the CM&E Project to evaluate land use,
ground water, soil profile, runoff, and climatic changes. Wells were located on seven fields;
six of the sites were farmed fields and one uncultivated. The three BMPs listed above have
been implemented on five of the sk farmed fields; one is a control site.
A total of 508 samples were collected and analyzed for pesticides from January 1984 to July
1987; 140 samples were collected in 1987. Quarterly sampling of 33 wells was conducted
in 1984. In 1985, monthly sampling of approximately 20 wells was initiated. Samples were
analyzed using GC/ECD. Positive detections were confirmed by GC/NP. Detection limits
were not specified for each pesticide, but ranged from 0.01 to 0.10 ug/L.
8-SD-5
-------
Results and Conclusions
Between 1984 and 1987, 46 samples had detectable levels of pesticides. The site specific
results of the monitoring are presented below:
Pesticide
County
&Site
Year
Wells Samples
No. Pos. No. Pos.
Avg.
Cone. Cue/!)
Alachlor
1985,86 12
1985-87 5
2
3
Atrazine
2,4-D
Brookings BL
BrookingsOP
HamlinLK
HamlinRS
HamlinJW
HamlinPH
Brookings BL 1985 12 1
80
69
4
4
030
1.03
1986
1985,86
1986
1985,86
10
14
4
9
2
2
2
2
82
98
61
83
2
13
2
4
0.10
0.59
0.10
0.11
1986
1986
12
5
2
1
Lindane
Metribuzin
Trifluralin
Brookings BL
Brookings OP
HamlinLK
HamlinRS
HamlinJW
HamlinPH
Brookings BL 1987 12 2
80
80
69
2
1
5.40
0.44
0.41
1986
1984,86
1986
1986
10
14
4
9
2
4
2
1
82
98
61
83
2
4
2
1
0.77
2.05
0.77
0.84
Brookings BL 1985
Hamlin RS 1986
12
14
HamlinPH
1985
80
80
98
83
1
1
0.05
0.02
0.025
0.02
The lindane found at the Brookings BL site was due to cattle treated with the pesticide
rubbing against monitoring wells. This pesticide was never actually in the ground water.
The majority of the pesticide detections are of low enough concentrations that the detection
limits of the equipment are being approached. Additional, 72% of the detections are single
events with no detections in the following monthly sample.
At each monitoring site land use histories were collected and updated annually. Pesticides
that have been used on the monitoring sites include:
alachlor
MCPA
bentazon
metribuzin
carbofuran
propachlor
2,4-D dicamba
trifluralin
Pesticide detections were represented by those with and without a history of on-site use.
Fifty percent of the pesticide detections have no use history (used within 2 years of
detection) on the site in which they were detected.
8-SD-6
-------
In the samples with pesticide detects alachlor was found 652% of the time, regardless of
a history of on-site use. The percent of detection of alachlor increases with respect to other
pesticide when on-site use is a criteria. Alachlor and 2,4-D are the most often used
herbicides on the project monitoring sites. Timing of pesticide detections was not uniform,
although detections appear to be seasonal. Sixty-nine percent (69%) of pesticide detections,
regardless of on-site use, occurred during the growing season (May-October). Forty percent
(40%) of detections occurred during June and July. There was an anomalous bulge in
detects in January 1986. This may have been caused by an unusual winter thaw and
infiltration through frost cracks. Desorption of organic chemicals from materials can be
triggered by temperature of pH changes and the cold water which may have infiltrated
would have caused a decided temperature change.
When only those samples with a history of on-site use were considered, an increase in the
percentage detections was observed in the post-application months of August and October.
From the land-use data available, it appeared that the average time for alachlor to appear
in ground-water samples following application was 7.7 months (17 samples). For 2,4-D the
average was 9.1 months (4 samples). In some cases the intervals between applications and
detections exceeded the time at which pesticide detections would be expected, based on
calculations using half life, partition coefficient and maximum solubility. Although
investigators did not find a direct correlation between annual precipitation and pesticide
detections, it did appear that storms of sufficient cumulative precipitation to cause
infiltration did directly influence the number of pesticide detections.
Based on the data collected it appears that under the climatic conditions found in Eastern
South Dakota, percolation of pesticides to the ground water is limited and sporadic. It also
appears that shallow sand and gravel aquifers, which would intuitively to be most vulnerable,
received a minor percentage of the pesticides reaching ground water. The high rate of
detection in glacial till was attributed to pesticide flow through secondary porosity channels
(macropores).
Bhatt, Kailash P., Project Leader and Contact, Hydrologist, Department of Water and
Natural Resources, Division of Environmental Regulations, Ground-Water Quality Program.
Tel: 605-773-3296. 1989 Pesticide and Nitrogen Sampling Program and 1990 Pesticide and
Nitrogen Sampling Program. Studies conducted in 1988-1990. (Reported January 1990,
77 pages, and February 1991, 63 pages, respectively).
Primary Objective
In 1988 the South Dakota Department of Water and Natural Resources (DWNR) initiated
a sampling program to assess the presence and extent of pesticides and nitrogen-based
fertilizers in ground water. Sampling began in May 1988 in the Parker-Centerville aquifer
in Turner County, and the program was expanded in 1989 to include the Bowdle aquifer in
Potter County. In 1990 sampling in irrigated and dry land areas was added to the program.
Data collected from land- and chemical-use surveys being conducted in conjunction with the
monitoring program will be used to help define the relationship between fanning practices
8-SD-7
-------
and ground-water contamination, and to aid fanners in developing Best Management
Practices (BMPs) to reduce agricultural chemical impacts on ground water.
Design
The Parker-Centerville aquifer was selected because of the intensive agriculture, extensive
irrigation, the potential for ground-water contamination with pesticides and fertilizers, and
its susceptibility for rapid infiltration to the ground water. The aquifer is vulnerable to
pesticide contamination from the land surface because of the presence of a shallow water
table and highly permeable horizons. The BowdJe aquifer was selected due to the shallow
ground-water occurrence and highly permeable soil, and the potential for ground-water
contamination as a result of land use. Monitoring sites were selected so as to reduce the
potential effect from point-source contamination such as chemical spill areas, septic tanks,
and sites restricted to livestock.
The original sampling network consisted of 24 monitoring wells at 10 sites in the Parker-
Centerville aquifer (Turner County). In 1989 10 wells at 7 sites in the Bowdle aquifer
(Potter County) were added, and in 1990 six wells (2 sites) were added in Turner County
and 5 wells (2 sites) were added in Potter County. Sampling for pesticides was conducted
monthly from May through October each year. Twenty-two Turner County wells were
sampled in 1988. In 1989, 12 Turner County wells and 14 Potter County wells were
sampled, and in 1990, 18 and 14 wells were sampled in Turner and Potter Counties,
respectively. Two wells in Turner County and 1 well in Potter county were never sampled
due to insufficient water levels.
Samples were analyzed for 18 pesticides commonly used in the two areas:
alachlor atrazine butylate carbofuran chloramben
cyanazine 2,4-D dicamba EPTC fonofos
MCPA metolachlor metribuzin pendimethalin phorate
picloram terbufos trifluralin
Analytical methodologies were chosen that were capable of detecting numerous pesticides
in an effort to collect as much data in the most efficient manner.
Results and Conclusions
In 1988 there were 6 Turner County (Parker-Centerville aquifer) wells with detections of
alachlor, dicamba or 2,4-D. One well was contaminated with all three pesticides. In 1989
eight Turner County wells and four Potter County (Bowdle Aquifer) were contaminated with
atrazine, cyanazine, 2,4-D, dicamba, or fonofos. Fonofos was the most frequently detected
pesticide.In 1990 six Turner County wells and two Potter County wells hade detections of
alachlor, metolachlor, metribuzin, picloram or trifluralin. Alachlor and metolachlor were
the most frequently detected pesticides.
All concentrations reported were low. Seventy-five percent of the pesticides detections in
the 1988 Pilot Program were from deeper portions of the Parker Centerville aquifer and
25% were from within 10 feet of the water table. In the 1989 study, 79% of the pesticide
detections were in samples from within 10 feet of the water table. Pesticide detections in
the Bowdle aquifer accounted for 29% of the total pesticide detections. Three of the four
8-SD-8
-------
detections were in samples from within 10 feet of the water table. Except for one Turner
County well, all wells with detections of pesticides in 1990 also had detections of pesticides
in 1989 and one had a sample containing a pesticide in 1988.
Even though some wells in this study showed detectable levels of pesticides in successive
years, the same pesticides were not detected in the same well in successive sampling periods.
This suggests possible dilution or natural degradation in the aquifer system. The results
from three years of sampling indicated that surface activities were the primary source of
pesticide presence in ground water.
8-SD-9
-------
PESTICIDE SWUNG IN THE STATE OF SOUTH DAKOTA
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
UELLS/SAMPLES
8-SD-ll
-------
PESTICIDE SMVLIIK IN TIE STATE OF SOOTI DAKOTA
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
8-SD-12
-------
PESTICIDE SAMPLING IN THE STATE OF SOUTH DAKOTA
(Cyanailne)
1990/5-10
18
98
TOTAL DISCRETE
WELLS/SAMPLES
99
789
0.11
1984-1987
17
149
1984-1987
40
359
1989/5-10
10
60
1990/5-10
14
80
1988/5-10
22
126
0.042
1989/5-10
12
66
1990/5-10
18
98
0.11
TOTAL DISCRETE
WELLS/SAMPLES
1984-1987
1984-1987
99
17
789
40
149
359
0.042-0.11
1989/5-10
10
60
1990/5-10
14
80
TURNER"
1988/5-10
22
126
1989/5-10
12
66
1990/5-10
18
.98
TOTAL DISCRETE
WELLS/SAMPLES
SROOKHJST.
1984-1987
99
17
789
149
1984-1987
40
359
1989/5-10
10
60
1990/5-10
14
80
1988/5-10
22
126
1989/5-10
12
66
1990/5-10
18
98
TOTAL DISCRETE
WELLS/SAMPLES
99
789
8-SD-13
-------
PESTICIDE SAMPLING » THE STATE OF SOUTH DAKOTA
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
8-SD-14
-------
PESTICIDE SAMPLING IN THE STATE OF SOUTH DAKOTA
1984-1987
17
149
1984-1987
40
359
1989/5-10
10
60
1990/5-10
14
80
0.10
1988/5-10
22
126
v
-------
PESTICIDE SMPLHG M WE STATE OF SOUTI DAKOTA
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
8-SD-16
-------
PESTICIDE SAMPLING IN THE STATE OF SOUTH DAKOTA
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
GRAND TOTAL
DISCRETE
WELLS/SAMPLES
Results from wells with detections were averaged for each site and pesticide. The values
listed are the range of these averages. Bendar. Oakwood Lakes-Poinsett RCWP
8-SD-17
-------
STATE OF SOUTH DAKOTA
IELLS BY COUNTY
17
1
12
13
19
19
14
28
26
26
99
1
63
64
NFU-Known or Suspected Normal Field Use
PS =Known or Suspected Point Source
UMK=Unknown
8-SD-19
-------
Well Sampling by County
(Total Number of Wells with Pesticide Detections / Total Number of Wells Sampled)
Wyomin
Total Wells Sampled
per County
• > 1BB0
m 501 to 1000
El 101 to 500
E2 51 to 100
E3 1 to 50
CD No wells sampled
Pesticides Detected
3,4-D
Dicamba
Picloram
8-WY-l
-------
WYOMING
OVERVIEW OF STATE LEGISLATIVE AND ENVIRONMENTAL POLICIES
REGARDING PESTICIDES IN GROUND WATER
Currently, there is no legislative mandate for ground water monitoring in the state of
Wyoming. However, some ground water monitoring is being performed under a
Cooperative Monitoring Agreement between the Wyoming Department of Agriculture, the
Wyoming Weed and Pest Control Districts and the United States Geological Survey. Under
this agreement three herbicides: 2,4-D, dicamba and picloram are monitored from
preselected well sites. These herbicides represent approximately 50% of all pesticide
application in the state. Site selection is determined by the Wyoming Department of
Agriculture and the Weed and Pest Control Districts, and may vary on a yearly basis.
REPORTED STUDIES OF PESTICIDES IN GROUND WATER
Druse, S. A.; et. aL Water Resources Data Wyoming Water Year 1987. US Geological Survey,
Water Resources Division, Cheyenne, WY. Tel:(307)772-2153.
Primary Objective
The emphasis of the USGS's monitoring program is surface water. However, the Water
Resources Division of the USGS includes a small number of ground water monitoring
stations within its water resources monitoring program for the state. Monitoring data is
gathered in cooperation with state, municipal, county and federal agencies to identify and
track Wyoming's water resources.
Design
Most of the 89 wells in the observation-well network are located in southeastern Wyoming
where there is extensive ground-water withdrawal. The methods for collection and analysis
of water samples are described in the "U.S. Geological Survey Techniques of Water-
Resources Investigations" manuals.
Results and Conclusions
Ground-water monitoring for pesticides was conducted only for special studies in specific
areas and thus is not representative of ground water throughout the state.
Five counties were monitored during this time period: Big Horn, Fremont, Natrona, Park
and Washakie. It must be noted that analysis was not performed for all pesticides in every
county. Big Horn county was the most frequently monitored and was monitored for a more
extensive list of pesticides than any other county. Of the 13 pesticides screened during the
sampling year, only three were detected. They were; 2,4,-D hi Natrona and Washakie
8-WY-3
-------
counties; dicamba in Big Horn, Park and Washakie counties; and picloram in Big Horn,
Natrona, Park and Washakie counties.
Hittle, George F. (1990) Herbicide Monitoring Program; 1990 Water Quality Analysis,
Wyoming Department of Agriculture/ USDI, Geological Survey. Point of Contact: State
of Wyoming Department of Agriculture, Cheyenne, Wyoming 82002-0100.
Primary Objective
The herbicide monitoring program was implemented in 1977 on the upper North Platte
River in Carbon County. Application of herbicides has increased over the years, therefore
the monitoring program has been expanded to other areas of the state.
The current program monitors thirty-six surface water sites plus twenty-five ground-water
quality sites per year. The purpose of the program was to determine the effects of herbicide
application on water quality in order to insure that State and Federal water quality
standards were not being exceeded, and determine whether herbicide concentrations were
adversely affecting drinking water supplies.
Design
Site selection for ground-water samples was performed by the United States Geological
Survey (USGS) and the Wyoming Department of Agriculture. Twenty-five new ground-
water sites are selected each year. Samples were analyzed by the USGS for pesticides using
equipment and methods described in Techniques of Water Resource Investigation". The
detection limits reported for the analytical methods are 0.01 ug/1. A non-zero value is any
concentration equal to or greater than the detection limit. Values less than the detection
limit are reported as <0.01 ug/1. The samples were analyzed for the herbicides picloram,
dicamba, and 2,4-D.
Results and Conclusions
Ground-water samples were collected and analyzed from sites during the years 1987-1990.
Twenty-six of the 75 wells sampled during this time period were found to contain at least
one herbicide. All three herbicides were detected over the time period. Dicamba and 2,4-D
concentrations were below 1 ug/liter, but picloram ranged up to 30 ug/liter and was the
most frequently found herbicide.
8-WY-4
-------
PESTICIDE SAMPLING IN THE STATE OF UTONING
8-WY-5
-------
PESTICIDE SWUNG IN THE STATE OF tiYONINfi
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
8-WY-6
-------
PESTICIDE SAMPLING IN THE STATE OF UTGMIKG
TOTAL DISCRETE
WELLS/SAMPLES
SHERIOAK
U1BTA -
WESTCW
1990/8.9
1989/8
1987/9
1990/9
1988/9
1987/8
1988/9
1989/8
19908/9
1988
1989/8,9
1989/8
1989/8
1989/8
1987/8
10
1988/8
1989/8
1987/8,11
1988/2-12
1989/1-12
1990/1-10
105
11
27
20
17
16
16
0.13
0.25
0.01
0.03
0.01-0.02
0.06-0.13
0.01
0.01-0.25
8-WY-7
-------
PESTICIDE SAMPLING III THE STATE OF VttMING
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
TOTAL DISCRETE
UELLS/SAMPLES
TOTAL DISCRETE
UELLS/SAMPLES
TOTAL DISCRETE
WELLS/SAMPLES
8-WY-8
-------
PESTICIDE SAMPLING IN THE STATE OF WTOMING
(Pfcloram)
1989/8
1987/9
0.01-0.04
1990/9
1988/9
1987/8
0.01-0.02
1988/9
1989/8
1990/8.9
19888/9
1989/8,9
1989/8
0.01
1989/8
0.01
1989/8
(USHMtlf
1987/8
0.01-0.16
1988/8
1989/8
WESTOH
1987/8,11
1988/2-12
27
21
1989/1-12
20
20
0.01-0.11
18.0
0.01-30.0
0.04-15.0
TOTAL DISCRETE
WELLS/SAMPLES
1990/1-10
17
16
105
24
163
80
0.02-11.0
0.01-30.0
GRAND TOTAL
DISCRETE
WELLS/SAMPLES
105
42
340
91
8-WY-9
-------
STATE OF tirONING
IELLS BY COUNTY
•s~.
10
Uifttd
Uaihakto
tfeston
TOt/tt.
78
26
27
16
26
16
NFU=Known or Suspected Normal Field
PS =Known or Suspected Point Source
UNKsUnknown
Use
8-WY-ll
-------
Pesticides in Ground Water Database -1992 Report
APPENDIX I - PESTICIDE CROSS-REFERENCE TABLE
-------
PESTICIDE CROSS-REFERENCE TABLE
Insecticide
Herbicide
U.C
1.2-D
Funigant
Funigant
1.3-D
1,3-D
Alachlor
Degradate
Carbofuran
Degradate
Carbofuran
Degradate
Pronamide
Parathion, methyl
Degradate
60
Degradate
Fungicide
4(2,4-Dichlorophenoxy)
butyric acid
4(2,4-08), Butoxyethanol
ester
APPENDIX 1-1
-------
PESTICIDE CROSS-REFERENCE TABLE
4<2,*-DB), Dtnethylanine
salt
Dicanba
Degradate
Iraecticido
Fungicide
Insecticide
Herbicide
Fungicide
Herbicide
Antimicrobial
S.R
Funigant
C,R,SR"
Herbicide
S,R,8RP
Insecticide
Acaricide
Fungicide
Hematictde
S,R,SRP
Aldicarb
Degradate
Aldicarb
Degradate
Aldicarb
Parent *
degradates
SRr
Insecticide
C.SR1"
60
60
Herbicide
Insecticide
Insecticide
Acaricide
S,R,SRW
Herbicide
S.Rr
Fungicide
s
so
Arsenates, Arsenites
Insecticide
Fungicide
Herbicide
Arsenic acid
Arsenicals
Arsenfe
Defoliant
Insecticide
SR
• f S1
'-r
experimental
discontinued triazlne
Herbicide
Herbicide
S,R
V
Atrazirte
Pegradate
Atf
Insecticide
Insecticide
S.R
Banvel
APPENDIX 1-2
-------
PESTICIDE CROSS-REFERENCE TABLE
Herbicide
Baygon
Insecticide
S.R
Benfluralin
Insecticide
Herbicide
Benfluralin
Fungicide
S.SIT
Herbicide
Bentttten-^
20
20
Herbicide
Bentazon
Degradate
w*
Insecticide
C,SRW
BHC (D
.
Bromaei I? \\ t * v ~ n o tf
90
Herbicide
Sodiin bromide
Herbicide
Insecticide
Herbicide
350
Herbicide
Fungicide
Fungicide
S,SIT
Carfaaryt
700
Insecticide
Carfaendatttt
Fungicide
40
Insecticide
Acaracide
Fungicide
Nematicide
S,R,SRU
Carbofuran
Degradate
total
Carbofuran
Parent *
degradates
str
Fumigant
Fungicide
Fire retardant
in fumigant
formulations
SR1"
Insecticide
Acaricide
Insecticide
Acaricide
APPENDIX 1-3
-------
PESTICIDE CROSS-REFERENCE TABLE
TOO
fungictde
Herbicide
100
Herbicide
U,C
Insecticide
Termlticide
C.SR?
Insecticide
C,SRC
Insecticide
Acaricide
Ovacide
C.SIT
Herbicide
U,C
Acaricide
U.C
Insecticide
Insecticide
Acaricide
Fungicide
Antimicrobial
100
turn)gant
Fungicide
Fumigant
Warning agent
S.R
Fungicide
Herbicide
20
Insecticide
Insecticide
Herbicide
Chlorthal dimethyl
Copper salts
Insecticide
Herbicide
Antimicrobial
Fungicide
some S
some u
Copper oxides
£>%; l?*'
Insecticide
Herbicide
Fungicide
Insecticide
Insecticide
Herbicide
S.R.SR1"
APPENDIX 1-4
-------
PESTICIDE CROSS-REFERENCE TABLE
200
200
Cyanide, catciun or
potassium
Rodenticfde
Cyanaide, sodium
Rodenticide
S,R
Herbicide
Insecticide
S,R
Herbicide
Dacthal
SCWt
Dacthal diacid
v ^'
CCP*
200
200
Herbicide
U,C
0.2
Fumigant
C,R,«r
OCBA
DCP
,
OCPA
4000
Herbicide
DCPA
Degradate
D-D Mix
and >1chUr
-------
PESTICIDE CROSS-REFERENCE TABLE
200
Herbicide
Herbicide
600
600
Antimicrobial
75
Insecticide
Fungicide ""
Rodenticide -
Antimicrobial
Nematicide
Funigant
S.R.SR'
Herbicide
S.SR'
Pre
Dfchlorprop, butoxyethanol
ester
Insecticide
Insecticide
Acaricide
S.SR11
Insecticide
S.R
Insecticide
c.sir
Diethylhexyt phthalate
Dactyl
Insecticide
Acaricide
Herbicide
C.SR1"
Dmitrocresol
y>
•ttftxs
Acaricide
Insecticide
C.R
200
Herbicide
20
20
Herbicide
Oiquat dibromide and
various salts
0.3
Insecticide
Acaricide
S.R
Disulfoton
&< eat fpit'oo- sutfox'^de-J "«
Oegradate
Disulfoton
Degradate
10
Herbicide
Fly larvieide
APPENDIX 1-6
-------
PESTICIDE CROSS-REFERENCE TABLE
Insecticide
Herbicide
Fungicide
Antimicrobial
U.C
DNOC, sodium salt
EDB
EBOC compounds
SRV
Fungicide
Antimicrobial
Endosulfan
I saner
xV?
Endosulfan
I saner
Endosulfan
Degradate
Sttitei
100
100
Herbicide
Insecticide
U,C,R.SRL
Endrin
Degradate
Insecticide
Acaricide
C,R
Herbicide
Herbicide
Insecticide
Acaricide
S,R
Insecticide
Fungicide
Nematicide
S,R
Disinfectant
Insecticide
.C.SR1
Ethylene
bi sdith i ocarbamate
Ethylfene
0.05
Insecticide
C.R.SR11
Ethylene dichloride
Ethylene thiourea
Ethyl parathion
EtrWi azote "
Fungicide
Maneb
Degradate
Fenac
Oilorfenac
Insecticide
Fungicide
Nematicide
S.R
APPENDIX 1-7
-------
PESTICIDE CROSS-REFERENCE TABLE
Fenamiphos
Degradate
Fenamiphos
Degradate
Fungicide
Insecticide
Acaricide
Insecticide
Fungicide
Nematicide
C.R
Insecticide
Herbicide
Insecticide
S.R
Herbicide
Herbicide
Herbicide
90
Herbicide
Aquatic
herbicide
10
Insecticide
S.R
V'-W
* /••'
••*•>, * v
1000
Fungicide
Antimicrobial
Ctyphoisate
700
700
Herbicide
Glyphosate isopropylamine
salt
Cuthi on
HCH (a.B.f)
HCH (D
*••%• x .,
0.4
Insecticide
C.SR1"
Heptachlor
0.2
Degradate
Seed
protectant
ftekaittaane- •..
200
Herbicide
ttydroxyatadtlor ;-;- -% < ^«
Alachlor
Degradate
^ j ^ •• ^cot^v
•.Vs -s sns?
Fungicide
Insecticide
Insecticide
Herbicide
S,R
Herbicide
APPENDIX 1-8
-------
PESTICIDE CROSS-REFERENCE TABLE
ICcpooc
0.2
0.2
Insecticide
s,K,sir
Herbicide
S,SRP
200
Insecticide
MaIathion
Degradate
fungicide
**f S?
f W.\ \ > *
Fungicide
10
Herbicide
some C,
some S
HCPA acids, salts, esters
Insecticide
MCPB salts, esters
MCPP salts, esters
MCPPA
Herbicide
Fungicide
Herbicide
U.C
Fungicide
Ketharaittophoa
Insecticide
Acaricide
S.R
Herbicide
Insecticide
Acaricide
S.R
Insecticide
Acaricide
Nolluscicide
Rodenticide
Bird repellant
S.R
ttethomyt
200
Insecticide
"• ^
%^C-"-p-p< •. X •"• " ff%:
•. •. ' %%% •>•.
Insecticide
Acaricide
Kethyt brtmltte
Insecticide
Antimicrobial
S,R
Methyl carbophenothion
Insecticide
Fungicide
Herbicide
S.R
paraoxon
Parathion, methyl
Oegradate
APPENDIX 1-9
-------
PESTICIDE CROSS-REFERENCE TABLE
Degradate
Netribuzin
Degradate
Insecticide
Acaricide
S.R
Insecticide
U.C
Insecticide
C.SIP
Herbicide
Nolinate
Degradate
x»4pr>QCTOt
Insecticide
Acaricide
Herbicide
C,SRC
«aled
..*,.
Insecticide
Acaricide
20
Insecticide
Insecticide
Herbicide
Herbicide
Memagon
Herbicide
p-llitrophenol
Chlordane
Impurity in
formulation
Herbicide
Insecticide
Fungicide
Antimicrobial
Ortho-dichlorobenzene
CryzaHn
Herbicide
Ovex
APPENDIX I-10
-------
PESTICIDE CROSS-REFERENCE TABLE
200
Insecticide
Acaricide
Fungicide
Nematicide
S,R
Chlordane
Ariinal
netabolfte
Insecticide
Acaricide
S.R.SR'
Insecticide
Acaricide
Herbicide
S.SR"
Para-chlorcmetacresol
para-Dichlorobenzene see
p-Dichlorobenzene, listed
at dichlorobenzene
30
Herbicide
S.R
Paraquat dichloride
Parathion
jtftttyt --v
Insecticide
S,R.SRW
Insecticide
S.R
PCH8
Fungicide
S.SR1
PCP
rPent6ekl oropher»t
Insecticide
Herbicide
Herbicide
Insecticide
Fungicide
Antimicrobial
S,R,SRr
Insecticide
Perthane
fethylan
Insecticide
S.R
Phorate
Degradate
Phorate
Degradate
Phorate
Degradate
" X* %^ '% %•- v.vX^\, '• •VX'iv' fjjfff
ffioratoxon sulforig >s<-^
Phorate
Degradate
Phorate
Degradate
Insecticide
Acaricide
U.R
Insecticide
APPENDIX 1-11
-------
PESTICIDE CROSS-REFERENCE TABLE
Phosmet
Degradate
Insecticide
C.R
500
500
Herbicide
S.R
Aphidtclde
Pirimicarb
Degradate
Insecticide
S.R
Herbicide
Insecticide
NR (In US)
100
Herbicide
Antimicrobial
Herbicide
S
50
Herbicide
S.R.SR'
Prop*
90
Herbicide
Herbicide
Insecticide
Acaricide
>V»1{
- * >^
10
Herbicide
100
Herbicide
Insecticide
S.SRr
Propyzamide
Prothiofos
froth! ojahos;
Insecticide
NR
Insecticide
Fungicide
Antimicrobial
Herbicide
Jiannel
Insecticide
U.C,SRW
Rotenone
Degradate
Insecticide
Acaricide
Piscicide
Herbicide
Herbicide
Silvex
Herbicide
Herbicide
APPENDIX 1-12
-------
PESTICIDE CROSS-REFERENCE TABLE
Herbicide
NR
Herbicide
NR
Sodiun bromide
Insecticide
Fungicide
Herbicide
Antimicrobial
Sodiun cyanide
Insecticide
S.R
Herbicide
TCA and salts
TCE
500
Herbicide
Telone
90
Herbicide
0.9
Insecticide
Fungicide
Nematicide
S.R
••r
Terbufos
Oegradate
TwrbwthytazW ^ \ \ x - "*
'''
Herbicide
Algaecide
Terfautryn
Herbicide
Terrazole
TetrttcM proettiy t ene
Fumigant
Insecticide
U,C
Thanite
Herbicide
Thiabcncarb atrtfoxltte
Degradate
Fungicide
Insecticide
Fungicide
S.SR1
Tordon
Insecticide
U.R.SR11
chlordane
Insecticide
Impurity in
formulation
S.R
Fungicide
APPENDIX 1-13
-------
PESTICIDE CROSS-REFERENCE TABLE
Herbicide
Insecticide
Herbicide
Trichlorobenzene
Trichloroethylene
Funigant
Insecticide
Fungicide
Herbicide
Antimicrobial
U.C
Trichlorophon
Insecticide
Herbicide
Fungicide
NR
*^SWi*'
J *• . tf.
Herbicide
S,S8,'
Trithion
Tunic
Antimicrobial
Herbicide
Vorlex
10000
10000
Insecticide
Fungicide
Herbicide
Antimicrobial
•> ' J5''y » ^^ i\x
f % A^
1-"^ ,* l-
Insecticide
Fungicide
Insecticide
Funaicide
Pre •
SRrrBPresently in Pre-Special Review
SR Special Review in progress
SR Special Review completed
S Supported: The producer(s> of the pesticide has made commitments to conduct
the studies and pay the fees required for reregistration, and is meeting
those conmitments in a timely manner.
APPENDIX 1-14
-------
PESTICIDE CROSS-REFERENCE TABLE
U Unsupported: The producer(s) of the pesticide has not made or honored a
connitnent to seek reregistration, conduct the necessary studies, or pay
the requisite fees for reregistration of the product.
C Canceled: The active ingredient is no longer contained in any registered
pesticide products.
R Restricted Use: The pesticide has been classified as a Restricted Use
Pesticide under 40 CFR Part 1, Subpart 1. It is therefore restricted to
use by a certified applicator, or by or under the direct supervision of a
certified applicator.
* In Hawaii both dichloropropane and 1,2-dichloropropane appear in the data.
Not Registered for use in the United States
APPENDIX 1-15
-------
Pesticides in Ground Water Database - 1992 Report
APPENDIX H - NATIONAL SURVEY OF PESTICIDES IN DRINKING
WATER WELLS
-------
At this time the Pesticides in Ground Water Database does not contain data from
the National Survey of Pesticides in Drinking Water Wells (NPS). These data have been
recently analyzed and published.3 OPP is currently working on importing the results of
the pesticide analyses, so that they will be available when the PGWDB becomes part of
the Pesticide Information Network. The following is a short description of the NPS and
a summary of findings from the NPS.
The NPS is a joint project of EPA's Office of Drinking Water and Office of
Pesticide Programs. This survey is the first national study of pesticides, pesticide
degradates and nitrate in drinking water wells. The Survey has two principal objectives:
1) to determine the frequency and concentration of pesticides and nitrate in drinking
water wells nationally; and 2) to improve EPA's understanding of how the presence of
pesticides and nitrate in drinking water wells is associated with patterns of pesticide use
and the vulnerability of ground water to contamination. The focus of the Survey was on
the quality of drinking water in wells, rather than on the quality of ground water, surface
water or drinking water at the tap. The Survey was designed to yield valuable
information on both the frequency and levels of pesticides, pesticide degradates and
nitrate in rural domestic (private) and community (public) drinking water wells on a
nationwide basis. The Survey was not designed to provide an assessment of pesticide
contamination in drinking water wells at the local, county or State level.
More than 1300 wells were sampled, some in each State, for 127 analytes. Nitrate
was the most commonly detected analyte in these wells. Based upon the NPS results
EPA estimates that nitrate is present at or above the analytical minimum reporting limit
of 0.15ug/L in about 52.1% or community wells, and 57% of rural wells nationwide.
The survey detected pesticides and pesticide degradates much less frequently than
nitrate. Twelve of the 126 pesticides and degradates were found in the sampled wells.
EPA estimates that 10.4% of community wells and 4.2% of rural domestic wells in the
United States contain pesticides or pesticide degradates at or above the analytical
minimum reporting limit. The two most commonly found pesticides were DCPA acid
metabolites (degradate of dimethyl tetrachloroterphthalate) and atrazine. The following
is a list of the pesticides found in each type of well in alphabetical order.
Community:
Rural Domestic:
atrazine, DCPA acid metabolites, dibromochloropropane,
dinoseb, hexachlorobenzene, prometon, simazine.
alachlor, atrazine, bentazon, DCPA acid metabolites,
dibromochloropropane, ethylene dibromide, ethylene thiourea,
gamma-BHC (lindane), prometon, simazine.
Appendix II-l
------- |